JPH0330616Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention is designed to reduce the amount of exhaust gas contained in an internal combustion engine equipped with a supercharger such as an exhaust turbocharger in the intake system.
This relates to a device for recirculating a portion of exhaust gas to the intake system for the purpose of reducing _NOx .

[Conventional technology]

In order to reduce _NOx in exhaust gas, it is effective to recirculate part of the exhaust gas to the intake system. It also applies to internal combustion engines. In this case, in order to recirculate the exhaust gas only in the engine idling and partial load ranges excluding high load ranges, there are two exhaust gas recirculation passages separated by a diaphragm in the exhaust gas recirculation passage connecting the intake system and the exhaust system. A reflux control valve having a pressure chamber is provided, the other pressure chamber of the reflux control valve is communicated with the atmosphere, and sensing is provided in one pressure chamber at a portion slightly upstream of the closed position of the throttle valve in the intake system. A configuration is generally adopted in which the intake negative pressure at the port is increased so that when the intake negative pressure increases toward the vacuum side, the valve body of the recirculation control valve operates in a direction to increase the opening area of the exhaust gas recirculation passage. ing.

When this general exhaust gas recirculation device is applied to an internal combustion engine with a supercharger, when the supercharging pressure of the intake system increases, the high pressure air-fuel mixture in the intake system is transferred to the exhaust gas connected to the intake system. A problem occurs in that the gas leaks from the gas recirculation passage through the sliding part of the valve stem of the recirculation control valve into the other pressure chamber communicating with the atmosphere, and is discharged from the other pressure chamber into the atmosphere.

Therefore, as prior art, Japanese Utility Model Application Publication No. 55-25686 and Japanese Utility Model Application Publication No. 57-2248 introduce supercharging pressure on the upstream side of the throttle valve into the other pressure chamber communicating with the atmosphere as described above. It is proposed that the leakage of the air-fuel mixture from the other pressure chamber is thereby prevented.

[The problem that the idea attempts to solve]

However, when the intake negative pressure is applied to one of the two pressure chambers divided by the diaphragm and the supercharging pressure is applied to the other pressure chamber,
When decelerating the engine from a high speed range, etc., when the engine is in a low load and high speed range, the engine speed is high and the boost pressure is high, and the throttle valve opens to the point where it touches the sensing port. In this state, one pressure chamber has a large negative pressure on the vacuum side at the sensing port, and the other pressure chamber is affected by the high supercharging pressure, causing the pressure between both pressure chambers to decrease. As the difference increases, the recirculation control valve opens fully and a large amount of exhaust gas is recirculated into the intake system, which significantly worsens the combustion of the mixture and causes HC
This also led to the problem of increased generation of other harmful gases such as CO.

The present invention aims to overcome this drawback of the prior art.

[Means to solve the problem]

To achieve this objective, the present invention provides a recirculation control valve having two pressure chambers separated by a diaphragm in the exhaust gas recirculation passage connecting the intake system and exhaust system of a supercharged internal combustion engine. , in one pressure chamber of the two pressure chambers of the recirculation control valve, the intake negative pressure at a sensing port provided at a portion slightly upstream of the closed position of the throttle valve in the intake system is set to a position where the intake negative pressure is a vacuum. The main valve member is introduced so as to operate in the direction of increasing the opening area of the exhaust gas recirculation passage. In an exhaust gas recirculation device that introduces pressure, the recirculation control valve has an opening area of the exhaust gas recirculation passage when the main valve member operates to make the opening area of the exhaust gas recirculation passage larger than a predetermined value. The structure is such that a sub-valve member is provided which operates in the opposite direction to contract the valve.

[Functions and effects of the idea]

With this configuration, when decelerating the engine from a high-speed rotation range by closing the throttle valve to the part that applies to the sensing port, the engine rotation speed is high and therefore the boost pressure is high, while the negative pressure at the sensing port is reduced. increases toward the vacuum side, the pressure difference between both pressure chambers increases, and when the main valve member in the recirculation control valve operates to fully open the exhaust gas recirculation passage, the auxiliary valve member operates to fully open the exhaust gas recirculation passage. Because it works to reduce the opening area of the passage,
When decelerating from a high-speed rotation range as described above, it is possible to reliably prevent a large amount of exhaust gas from flowing back into the intake system.

The sub-valve member is configured to operate in a direction to conversely reduce the opening area of the exhaust gas recirculation passage when the main valve member operates to make the opening area of the exhaust gas recirculation passage larger than a predetermined value. The presence of the sub-valve member does not reduce the amount of exhaust gas recirculated to the intake system in the partial load range near where the throttle valve contacts the sensing port, and the amount of exhaust gas returned to the intake system in the partial load range The amount of gas reflux can be ensured.

Therefore, according to the present invention, in a supercharged internal combustion engine, the amount of exhaust gas recirculated to the intake system can be accurately controlled according to the load without causing any leakage of the air-fuel mixture to the outside. However, when decelerating the engine from a high-speed rotation range, a large amount of exhaust gas recirculates to the intake system, which can increase HC and CO in the exhaust gas and worsen drivability. It has the effect of ensuring prevention.

〔Example〕

Hereinafter, a drawing will be explained in which an embodiment of the present invention is applied to an internal combustion engine with an exhaust turbo supercharger. In the drawing, reference numeral 1 indicates an internal combustion engine having an intake manifold 2 and an exhaust manifold 3
Reference numeral 4 indicates an exhaust turbo supercharger in which an exhaust turbine 5 and a blower compressor 6 are directly connected, and an intake passage connecting the discharge side of the blower compressor 6 in the exhaust turbo supercharger 4 to the intake manifold 2. 7, a surge tank 8 for eliminating pulsation and a carburetor 9 with a throttle valve 10 are provided such that the surge tank 8 is located upstream of the carburetor 9,
An air cleaner 11 is installed on the suction side of the blower compressor 6.
is connected to the exhaust manifold 3 via an exhaust passage 12 to the inflow side of the exhaust turbine 5.
However, exhaust pipes 13 to the atmosphere are connected to the exit sides of the exhaust turbines 5, respectively.

Reference numeral 14 indicates an exhaust gas recirculation device, and the exhaust gas recirculation device 14 includes an exhaust gas recirculation passage 15 connecting the intake manifold 2 and the exhaust passage 12;
It consists of a diaphragm type exhaust gas recirculation control valve 16 inserted into the exhaust gas recirculation passage 15, and the exhaust gas recirculation control valve 16 is equipped with a diaphragm 20 that partitions into two pressure chambers 18 and 19. Main valve body 22 connected via 21
is always urged in the closing direction by the spring 23 in the one pressure chamber 18 so as to contact the upper surface of the valve seat 24, and the one pressure chamber 18 is pressed against the throttle valve 10 in the carburetor 9. Closed position (idle opening)
The pressure chamber 19 is connected to a sensing port 25 provided at a slightly upstream position via a negative pressure transmission passage 26, and the other pressure chamber 19 is connected to the surge tank 8 via a supercharging pressure transmission passage 27.

Further, the main valve body 22 of the exhaust gas recirculation control valve 16 has an opening area that exceeds a predetermined value when the main valve body 22 moves upward from the upper surface of the valve seat 24 to increase the opening area of the passage. Conversely, a sub-valve body 28 is integrally provided so as to approach the lower surface of the valve seat 24 so as to close the passage.

In this configuration, when the throttle valve 10 in the carburetor 9 is in an idling state with the throttle valve 10 closed, the carburetor 9
The sensing port 25 is located upstream of the throttle valve 10 and
Since no negative pressure is generated in the reflux control valve 16, the main valve body 22 of the reflux control valve 16 is closed and exhaust gas is not recirculated to the intake system. is not carried out.

When the throttle valve 10 is opened from this state, negative pressure is generated in the sensing port 25, and this negative pressure acts on one pressure chamber 18, causing the main valve body 22 to move toward the valve seat 2.
Since it rises away from 4 and opens the passage, the exhaust gas is recirculated to the intake system.
As the opening degree of the throttle valve 10 further increases, the negative pressure at the sensing ports 25 decreases to approach atmospheric pressure, and the main valve body 22 of the reflux control valve 16
Since the passage is closed by the spring 2 in contact with the upper surface of the valve seat 24, the recirculation of the exhaust gas to the intake system is cut off, and at the same time, the exhaust turbo overflow occurs as the amount of exhaust gas from the engine 1 increases. The rotation of the feeder 4 becomes faster and supercharging is performed.

Further, since the supercharging pressure upstream of the throttle valve 10 is introduced into the other pressure chamber 19 of the recirculation control valve 16, the intake pressure downstream of the throttle valve 10 is increased due to the supercharging. Even if the pressure exceeds the atmospheric pressure, the mixture from the carburetor 9 will not leak out from the exhaust gas recirculation passage 15 through the sliding part of the valve stem 21 into the other pressure chamber 19.

During deceleration with the throttle valve 10 closed from a fully open state to a partially open state (that is, the opening degree of the sensing port 25), the supercharging pressure upstream of the throttle valve 10 is While increasing due to the inertial rotation of the machine 4, the intake pressure at the sensing port 25 increases toward the vacuum side, so the pressure on the vacuum side and the supercharging pressure act on both pressure chambers 18 and 19 in the reflux control valve 16, respectively. As a result, the pressure difference between the two increases, causing the main valve body 22 to move upwardly from the valve seat 24. Due to this large upward movement, the subvalve body 28, which is integrally provided therewith, touches the bottom surface of the valve seat 24. Since the passage is closed by contacting the exhaust gas, exhaust gas is not returned to the intake system. In other words, in the deceleration operation range where the supercharging pressure increases and the intake pressure increases toward the vacuum side by introducing the supercharging pressure into the other pressure chamber 19 to prevent air-fuel mixture leakage, The sub-valve body 28 can reliably prevent a large amount of exhaust gas from being returned to the intake system.

In addition, in the above embodiment, the sub-valve body 28 is used as the sub-valve member.
, but as other examples,
In place of the sub-valve body 28 shown in FIG. 1, a sub-valve body 29 is provided on the upper part of the valve body 22 as shown in FIG. It is also possible to use a sub-valve member configured to approach each other and close the passage, and the present invention is applicable not only to internal combustion engines with an exhaust turbo supercharger, but also to engines with a mechanical supercharger linked to a crank. Needless to say, the same can be applied to internal combustion engines. Furthermore, although the embodiment has been described with respect to an intake negative pressure type exhaust gas recirculation device, it goes without saying that the present invention can be similarly applied to an exhaust pressure type exhaust gas recirculation device.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing a sub-valve member in another embodiment. 1... Internal combustion engine, 4... Exhaust turbo supercharger, 9
... Carburizer, 10 ... Throttle valve, 15 ... Exhaust gas recirculation passage, 16 ... Exhaust gas recirculation control valve,
20...Diaphragm, 18, 19...Diaphragm chamber, 22...Main valve body, 24...Valve seat, 28...
... Sub-valve body, 29... Sub-valve seat.

Claims (1)

[Scope of utility model registration request] A recirculation control valve having two pressure chambers separated by a diaphragm is provided in an exhaust gas recirculation passage connecting an intake system and an exhaust system in an internal combustion engine with a supercharger, and the two pressure chambers in the recirculation control valve are provided. In one of the pressure chambers, the main valve member detects the intake negative pressure at a sensing port located slightly upstream of the closed position of the throttle valve in the intake system, and when the intake negative pressure increases toward the vacuum side, the main valve member An exhaust gas recirculation device that operates in a direction to increase the opening area of the recirculation passage, while introducing pressure upstream of a throttle valve in an intake system into the other diaphragm chamber of the two pressure chambers. In the recirculation control valve, when the main valve member operates to make the opening area of the exhaust gas recirculation passage larger than a predetermined value, the recirculation control valve operates in a direction to conversely reduce the opening area of the exhaust gas recirculation passage. An exhaust gas recirculation device for an internal combustion engine equipped with a supercharger, characterized in that an auxiliary valve member is provided.