JPS6020576B2 - Exhaust gas recirculation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust gas recirculation system for an internal combustion engine that reduces harmful components, particularly NQ, in exhaust gas.

As is well known, in an internal combustion engine, the temperature of the combustion chamber does not reach a high temperature due to various reasons during idling operation, full load operation, deceleration operation, etc., and therefore the exhaust gas contains less rJ○x but more HC and CO.

Furthermore, when the engine is operating under acceleration or under partial load, the air-fuel mixture is efficiently combusted, so the combustion temperature rises significantly, and the exhaust gas contains less HC and CO, but more N*x. HC and CO in the exhaust gas mentioned above can be reduced relatively easily by using secondary air and various rekindling competition devices, while N
Regarding ○x, part of the secondary exhaust gas is recirculated to the engine intake system and introduced into the air-fuel mixture to lower the combustion temperature in order to reduce N○x. During full load operation, deceleration operation, etc., there is a drawback that combustion is deteriorated and drivability is worsened.

Generally, the recirculated exhaust gas is configured to be guided through the intake manifold downstream of the throttle valve of the carburetor in the intake system, and the exhaust gas supply is controlled by the back pressure of the exhaust manifold and the negative pressure of the intake manifold. Therefore, when the throttle valve opening is small, i.e. when idling or during engine braking, when the intake manifold pressure is high and the engine is under low load, exhaust gas is regenerated. When the amount of circulation is large and the above-mentioned valve opening is large, that is, when the intake manifold negative pressure is small in the engine, at high load, and at full load, the amount of exhaust gas recirculated tends to be small. While a large amount of x is generated, the amount of exhaust gas recirculated is small at high loads. Increasing the area of the exhaust gas circulation passage,
This has disadvantages in that it causes a decrease in output when the engine is fully loaded, makes the engine rotation unstable at idle, increases HC and CO in the exhaust gas, and causes vibrations and engine stoppage.

This is proposed in view of the exhaust gas recirculation device for an internal combustion engine of the present invention, in which a passage in the middle of the exhaust gas recirculation passage for sucking a part of the exhaust gas into the intake system is formed integrally with the carburetor, and the same passage is arranged close to and parallel to the intake passage of the carburetor, has a variable throttle valve interlocked with the throttle valve of the carburetor, is formed by the inner wall of the intake manifold and the partition wall, and is disposed close to and parallel to the intake passage. The gist of the present invention is an exhaust gas recirculation device characterized in that the exhaust gas recirculation passage passes through exhaust gas recirculation passages arranged in parallel and closes into a main passage at a bent portion at the bottom of the intake manifold.

Next, one embodiment of the present invention will be described with reference to the drawings.

The downstream side intake passage 2, the secondary side intake passage 3, and the exhaust gas recirculation passage 4 provided in the two lotus type carburetor 1 are arranged in parallel,
The upper ends of the primary and secondary intake passages 2 and 3 are passed through a cleaner 5, and the lower ends are passed through an intake manifold 6. Further, the exhaust gas recirculation passage 4 is connected to an exhaust passage (not shown) via a pipe 7, and its lower end is fitted into a passage 9 formed by the inner wall of the intake manifold 6 and the partition wall 8. 9 is passed through the main passage 10 of the intake manifold 6 near the bottom of the bent portion of the intake manifold 6. Furthermore, a throttle valve 1 is interposed in the primary intake passage 2 in the middle of the exhaust gas recirculation passage 4.
In this embodiment, a link mechanism 13 is used to change the opening degree of the variable throttle valve 12 substantially in proportion to the throttle valve 11. Although not shown, the exhaust gas recirculation passage such as a pipe is equipped with other flow rate control valves, etc., which are controlled by negative pressure, such as Venturi member pressure, approximately proportional to the amount of intake air. Appropriate flow rate control is performed according to the

According to the above-mentioned basic structure, the variable throttle valve 12 is also throttled when the valve opening of the throttle valve 11 is small during idling, during engine braking, and when the intake manifold negative pressure is large during low load of the engine. In an engine where the throttle valve 11 has a large valve function, when the intake manifold negative pressure is small during high load, the variable throttle valve 12 reduces its throttle amount in accordance with the throttle valve 11.
While a large amount of N○x is generated, the amount of exhaust gas recirculated is increased at high loads to sufficiently reduce the generation of NQ, and the amount of recirculated exhaust gas is reduced at times such as idling or low load when the amount of NQ generated is small. This not only increases engine output and reduces fuel consumption, but also reduces the amount of unburned gas in the exhaust gas. Moreover, according to the above-mentioned slow growth, the throttle valve 1
1 and the variable throttle valve 12 are arranged adjacent to each other, the structure of the link mechanism 13 that links the variable throttle valve 12 to the throttle valve 11 becomes simple and inexpensive, and the partition wall 8 is provided on the intake manifold 6. Therefore, there is no need to worry about exhaust gas flowing back through the main passageway IQ and polluting the fuel passages such as the slow system provided in the carburetor.

[Brief explanation of the drawing]

The drawings are schematic representations of embodiments of the invention. DESCRIPTION OF SYMBOLS 1... Carburetor, 2... Primary side intake passage, 3... Secondary side intake passage, 4... Exhaust gas recirculation passage, 6... Intake manifold, 7... Pipe, 8...・Partition wall, 9... Passage, 10... Main passage, 11... Throttle valve, 1
2...Variable throttle valve, 13...Link mechanism.

Claims (1)

[Claims] 1. A passage 4 in the middle of the exhaust gas recirculation passage that sucks a part of the exhaust gas into the intake system is formed integrally with the carburetor, and the passage is arranged close to and parallel to the intake passages 2 and 3 of the carburetor 1. A variable throttle valve 12 interlocked with the throttle valve 11 of the carburetor 1 is interposed, and is formed by the inner wall 6 and partition wall 8 of the intake manifold, and is arranged close to and parallel to the intake passages 2 and 3. An exhaust gas recirculation device characterized in that the exhaust gas recirculation passage 9 opens into a main passage 10 at a bent portion at the bottom of the intake manifold 6.