JPS6148628B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides
This invention relates to an exhaust gas recirculation device of exhaust pressure control type that recirculates a portion of exhaust gas to the intake system for the purpose of reducing NOx.

[Prior Art] This exhaust pressure control type exhaust gas recirculation device, as described in, for example, Japanese Unexamined Patent Publication No. 49-15820 or Japanese Utility Model Application No. 51-147821, etc. A pressure-operated recirculation control valve is provided in the recirculation passage that recirculates the air to the intake system, and a pressure chamber in the recirculation control valve and a sensing port are provided at a portion of the carburetor slightly upstream from the closed position of the throttle valve. The reflux control valve is connected to the sensing port through a negative pressure transmission passage so as to open when negative pressure acts on the pressure chamber, and an atmospheric air introduction passage is connected to the negative pressure transmission passage, and a The exhaust pressure regulating valve introduces atmospheric air into the negative pressure transmission passage when the pressure of exhaust gas in an internal combustion engine is low, and shuts off the introduction of atmospheric air into the negative pressure transmission passage as the pressure of exhaust gas increases. It is configured with the following.

[Problem that the invention seeks to solve]

However, in a light load range where the throttle valve is slightly opened to the point where it is applied to the sensing port of the throttle valve, when the atmospheric air introduction passage is blocked by the exhaust pressure regulating valve, the large negative pressure generated at the sensing port remains unchanged. This acts on the recirculation control valve and causes the recirculation control valve to open rapidly, causing the recirculation of exhaust gas to the intake system to rise rapidly from the start of recirculation, resulting in unstable combustion in the light load range. If this happens, drivability will deteriorate, and in severe cases, misfires will occur. Furthermore, when the throttle valve opens past the sensing port, the negative pressure generated at the sensing port decreases to near atmospheric pressure, and the recirculation control valve closes. The amount of gas recirculated is not proportional to the opening degree of the throttle valve, that is, the negative pressure of the engine.

The present invention solves the above-mentioned problems in such an exhaust pressure control type exhaust gas recirculation device, that is, the recirculation control valve opens suddenly at the start of recirculation, and the operation in which exhaust gas is recirculated to the intake system. This solves the problem that the recirculation amount is not proportional to the engine load in the region.

[Means for solving problems]

For this reason, the present invention provides a pressure-operated recirculation control valve in a recirculation passage that recirculates part of the exhaust gas to the intake system in an internal combustion engine, and a pressure chamber in the recirculation control valve and a throttle valve in a carburetor of the internal combustion engine. A sensing port provided at a location slightly upstream of the closed position of the sensor is connected via a negative pressure transmission passage so that the reflux control valve opens when negative pressure at the sensing port acts on the pressure chamber. An atmospheric air introduction passage is connected to the negative pressure transmission passage, and when the exhaust gas pressure in the internal combustion engine is low, atmospheric air is introduced into the negative pressure transmission passage, and the negative pressure is increased as the pressure of the exhaust gas increases. In an exhaust gas recirculation device comprising an exhaust pressure regulating valve configured to block introduction of atmospheric air into a transmission passage, the carburetor is provided with a second sensing port at a location further upstream from the sensing port, The second sensing port is connected to the negative pressure transmission passage.

[Effect]

In this way, in the negative pressure transmission passage that connects the sensing port at a portion slightly upstream of the closed position of the throttle valve and the pressure chamber of the reflux control valve, a second valve is provided at a portion further upstream from the sensing port.
When the sensing port is connected, when the atmospheric air introduction passage connected to the negative pressure transmission passage is shut off by the exhaust pressure regulating valve, the pressure chamber of the reflux control valve contains the negative pressure of the sensing port and the second sensing port. Combined with the negative pressure, a composite negative pressure will act, and this composite negative pressure is close to atmospheric pressure when the throttle valve opening is small, and increases toward the vacuum side as the throttle valve opening increases, so the reflux The control valve is
This makes it possible to prevent the valve from suddenly opening when the recirculation starts, and to make the opening degree of the recirculation control valve approximately proportional to the opening degree of the throttle valve in the operating range in which exhaust gas is recirculated to the intake system.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings (Fig. 1), in which 1 is an internal combustion engine, 2 is an intake pipe equipped with a carburetor 3, 4 is an exhaust pipe, and 6 is a pressure-operated engine such as a diaphragm. Each of the reflux control valves is shown, the inlet of the reflux control valve 6 is connected to the exhaust pipe 4 via a reflux passage 7 with an orifice 8, and the outlet of the reflux control valve 6 is connected to the intake pipe 2 via a reflux passage 9. The valve body 10 of this reflux control valve 6 is urged in the normally closed direction by a spring 5 in a pressure chamber 11, and the pressure chamber 11 is connected to the vaporizer 3 through a negative pressure transmission passage 12 with an orifice 13. It is connected to a sensing port 15 provided at a location slightly upstream of the closed position (idle opening) of the throttle valve 14.

Reference numeral 16 designates an exhaust pressure regulating valve, which includes a diaphragm 19 that separates a negative pressure regulating chamber 17 and an exhaust pressure chamber 18, communicates the negative pressure regulating chamber 17 with the atmosphere through an orifice 20, and The pressure adjustment chamber 17 has an orifice 13 for the negative pressure transmission passage 12.
The connected atmospheric air introduction passage 21 is opened at a portion closer to the reflux control valve 6 .

The diaphragm 16 of the exhaust pressure regulating valve 16 is provided with a flap 22 for opening and closing the opening of the atmospheric air introducing passage 21 to the negative pressure regulating chamber 17, and a spring 23 keeps the atmospheric introducing passage 21 open. While maintaining the vacuum chamber 1 on the opposite side of the negative pressure adjustment chamber 17 with the diaphragm 19 in between,
The exhaust gas pressure between the recirculation control valve 6 and the orifice 8 in the recirculation passage 7 is introduced into the recirculation passage 8 through the passage 24, and when the pressure of the exhaust gas increases, the flap 22 in the diaphragm 19
It is configured to block communication of the atmospheric air introduction passage 21 with the negative pressure adjustment chamber 17.

A second sensing port 25 is provided in the vaporizer 3 at a location further upstream from the sensing port 15, and the second sensing port 25 is connected to the negative pressure passage 26 with an orifice 27. It is connected to the pressure transmission passage 12.

In this configuration, when the throttle valve 14 is fully closed and in an idling state, the sensing port 15 and the second sensing port 25 are both located upstream of the throttle valve 14 and are at atmospheric pressure. Therefore, the pressure chamber 11 of the reflux control valve 6
Since the pressure becomes atmospheric pressure, the valve body 10 is closed without opening, and the exhaust gas is not recirculated to the intake system.

Next, in a light load range where the throttle valve 14 is slightly opened, the throttle valve 14 applies only to one of the sensing ports 15 closest to it, and a large negative pressure is generated in the sensing port 15. 2 Sensing port 25 is the throttle valve 1
4, the second sensing port 25 does not generate negative pressure and remains at atmospheric pressure, while the exhaust gas pressure is low and the exhaust pressure regulating valve 16 Atmospheric introduction passage 2
1 is open, atmospheric air is introduced into the negative pressure transmission passage 12 from the atmosphere introduction passage 21, and the large negative pressure at the one sensing port 15 is transmitted to the pressure chamber 11 in the recirculation control valve 6. To prevent this, the recirculation control valve 6 does not open, but if the pressure of the exhaust gas increases with the opening of the throttle valve 14, the diaphragm 19 in the exhaust pressure regulating valve 16 closes the atmospheric air introduction passage 21, reducing the negative pressure. Since the introduction of atmospheric air into the transmission passage 12 is blocked,
A composite negative pressure of the large negative pressure at the one sensing port 15 and the atmospheric pressure at the second sensing port 25 acts on the pressure chamber 11 of the reflux control valve 6, and the valve body 10 of the reflux control valve 6 The exhaust gas is recirculated to the intake system by opening by an opening degree corresponding to this synthetic negative pressure.

When the throttle valve 14 is further opened to increase the load, the throttle valve 14 is applied to the second sensing port 25, and negative pressure is generated not only in one sensing port 15 but also in the second sensing port 25.
The combined negative pressure of the two is determined when negative pressure is generated only in one of the sensing ports 15, that is, in a light load region where the throttle valve 14 is applied only to the one sensing port 15 that is close to the throttle valve 14. Since the opening of the recirculation control valve 6 increases, the amount of recirculation of exhaust gas to the intake system increases, and at full load with the throttle valve 14 fully open, The negative pressure in one sensing port 15 and the negative pressure in the second sensing port 25 both approach atmospheric pressure and the recirculation control valve 6 closes, so that the recirculation of exhaust gas to the intake system is stopped.

In this case, the second sensing port 2 communicating with the negative pressure transmission passage 12 as in the prior art
5 is not provided, in a light load range when the throttle valve 15 is applied to one sensing port 15, the large negative pressure generated at the sensing port 15 is directly transferred to the pressure chamber 1 of the recirculation control valve 6.
1 and the recirculation control valve 6 opens rapidly, a large amount of exhaust gas is recirculated to the intake system in the light load range where recirculation starts, while the negative pressure at the sensing port 15 is
When the throttle valve 14 passes through the sensing port 15, the pressure rapidly drops to near atmospheric pressure and the reflux control valve 6 closes. It's not proportional.

In addition, as shown in FIG. 2, the orifice 20 for communicating the negative pressure adjustment chamber 17 with the atmosphere in the exhaust pressure adjustment valve 16 is eliminated, and the negative pressure adjustment chamber 17 is made into a sealed chamber. When the negative pressure passage 26 from the second sensing port 25 is connected to the pressure adjustment chamber 17, in the operating range where the throttle valve 14 is connected to the second sensing port 25, one sensing port is connected to the pressure adjustment chamber 17. 15 and the second sensing port 25, the recirculation control valve 6 always performs only negative pressure control regardless of the control by the exhaust pressure regulating valve 16. Therefore, the throttle valve 14 The recirculation amount of exhaust gas in the load range applied to the two sensing ports 25 can be increased to some extent than in the case of the prior art, but the In the light load range of the opening degree, when the atmospheric air introduction passage 21 is shut off by the exhaust pressure regulating valve 16, the pressure chamber 11 in the reflux control valve 6 has negative pressure in the sensing port 15 and negative pressure in the second sensing port 25. Since the large negative pressure in the sensing port 15 acts as it is without the negative pressure combined with the pressure acting on it, the recirculation control valve 6 suddenly opens wide, reducing the amount of recirculation of exhaust gas to the intake system. increases rapidly from the start of reflux.

In contrast, in the present invention, the second sensing port 25 is not connected to the negative pressure adjustment chamber 17 in the exhaust pressure adjustment valve 16 as described above, and the reflux control valve 16
This is connected to the negative pressure transmission passage 12 to the pressure chamber 11 in the air introduction passage 2.
1 is shut off by the exhaust pressure regulating valve 16, the throttle valve 1 is connected to the pressure chamber 11 of the recirculation control valve 6.
4 and the negative pressure at the second sensing port 25 which is further away from the throttle valve 14 can be applied. This composite negative pressure is close to atmospheric pressure when the opening degree of the throttle valve 14 is small, and increases toward the vacuum side as the opening degree of the throttle valve 14 increases. In addition, the opening of the throttle valve 14 is increased so that the opening of the recirculation control valve 6 is small when the opening of the throttle valve 14 is small, and large when the opening of the throttle valve 14 is large. It is possible to make it approximately proportional to the degree.

〔Effect of the invention〕

Therefore, according to the present invention, it is possible to suppress the rapid increase in the amount of exhaust gas recirculation during light loads, which is a drawback of conventional exhaust pressure control systems, and to make the increase in the amount of exhaust gas recirculation more gradual. While combustion in the engine is stable and drivability can be improved, in the operating range where exhaust gas is recirculated to the intake system, the amount of recirculation of exhaust gas can increase in proportion to the engine load. This has the effect of effectively and reliably achieving NOx reduction through reflux.

[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 exhaust gas recirculation apparatus before the present invention. 1... Engine, 2... Intake pipe, 3... Carburetor, 4
...Exhaust pipe, 6...Pressure-operated reflux control valve, 7,
9... Return passage, 11... Pressure chamber, 12... Negative pressure transmission passage, 14... Throttle valve, 15... Sensing port, 16... Exhaust pressure adjustment valve, 17... Negative pressure adjustment chamber, 18... ...Exhaust pressure chamber, 19...Diaphragm, 21...Atmospheric introduction passage, 25...Second sensing port, 26...Negative pressure passage.

Claims (1)

[Claims] 1. A pressure-operated recirculation control valve is provided in the recirculation passage that recirculates part of the exhaust gas in the internal combustion engine to the intake system, and the pressure chamber in the recirculation control valve and the throttle valve in the carburetor of the internal combustion engine are located in the closed position. A sensing port provided on the upstream side is connected via a negative pressure transmission passage so that the reflux control valve opens when negative pressure at the sensing port acts on the pressure chamber, and a An atmosphere introduction passage is connected to the atmosphere introduction passage, and when the pressure of exhaust gas in the internal combustion engine is low, the atmosphere is introduced into the negative pressure transmission passage, and as the pressure of the exhaust gas increases, the atmosphere is introduced into the negative pressure transmission passage. In the exhaust gas recirculation device, the carburetor is provided with a second sensing port located further upstream than the sensing port, and the second sensing port An exhaust gas recirculation control device for an internal combustion engine, characterized in that an exhaust gas recirculation control device for an internal combustion engine is connected to the negative pressure transmission passage.