JPS6111480Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an exhaust gas recirculation device for an engine.

As an engine exhaust gas recirculation device that suppresses the generation of nitrogen oxides NOx by recirculating a part of the engine exhaust gas to the intake system,
An exhaust gas recirculation passage is provided with one end opening into the engine exhaust system and the other end opening into the intake passage between the carburetor bench lily and the throttle valve. A flow control valve that closes the exhaust gas recirculation passage is provided, and one end opens into the exhaust gas recirculation passage downstream of the flow control valve, and the other end opens into the intake passage downstream of the fully closed Chiyork valve and upstream of the vent lily. A device having an open air passage was previously proposed by the same applicant (see Japanese Patent Laid-Open No. 53-67022). In the exhaust gas recirculation device of this prior application, when the exhaust gas recirculation is stopped, air from the air passage is added to the air flowing through the bench lily and the fuel, so a relatively lean mixture is formed and fuel efficiency is improved. When the exhaust gas is recirculated, the air from the air passage is blocked by the exhaust gas pressure in the exhaust gas recirculation passage, so a relatively rich air-fuel mixture is formed and combustibility is ensured.

By the way, the above exhaust gas recirculation stops when the engine is cold, for example, when the engine cooling water temperature is low and below 55℃, or when the intake air temperature is low and 20℃.
This is carried out in the following cases and in the required operating range after the engine has warmed up, such as when the engine is rotating at high speed or when the transmission is in a high speed range. The reason for this is that when the engine is cold, the amount of NOx generated is small, and at this time the combustion condition is inherently poor, so if the exhaust gas is recirculated, the combustibility will deteriorate significantly.Also, when the engine is running at high speed, the engine This is to ensure reliability, and also because this operating range is a steady operating range when the high-speed range is used, and the amount of NOx generated is small. The air-fuel ratio of the air-fuel mixture when the recirculation is stopped is set based on the required operating range after engine warm-up, which is frequently used, with emphasis on improving fuel efficiency. When the engine is cold, which requires a richer air-fuel mixture, the air-fuel mixture becomes leaner than the required air-fuel ratio. Since the other end of the air passage opens on the downstream side of the choke valve in the closed state, the air from the air passage is throttled to enrich the air-fuel mixture and maintain it at the required air-fuel ratio.

However, the engine exhaust gas recirculation device of the above-mentioned prior application has the characteristics of the recent chiyok valve, which is used to protect the catalytic exhaust gas purification device installed in the exhaust system and prevent plugs from smoldering before the engine warms up. Since the engine is set to open the engine valve when the engine is warmed up, the air-fuel mixture becomes lean during the period from when the engine valve is opened until warm-up is complete, causing the engine's combustion characteristics to deteriorate. There was a problem that negatively affected running performance.

This invention solves the problem of the semi-warmed state by closing the air passage when the engine is cold.

A first embodiment of this invention will be described below with reference to FIG.

1 is a carburetor, 2 is a choke valve, 3 is a main nozzle, 4 is a bench lily, 5 is a throttle valve, 6 is an intake manifold, 7 is an intake passage, 8 is an engine, 9 is an exhaust pipe, 10 is a catalytic exhaust gas purification It is a device. The exhaust gas recirculation passage 11 that communicates the exhaust pipe 9 and the intake passage 7 has one end open to the exhaust pipe 9 and the other end opened to the intake passage 7 between the bench lily 4 and the throttle valve 5. A flow control valve 12 equipped with a diaphragm device 12a is interposed in the exhaust gas recirculation passage 11. The air passage 13 has one end communicating with the exhaust gas recirculation passage 11 on the downstream side of the flow control valve 12, and the other end is an intake passage downstream of the fully closed valve 2 and upstream of the bench lily 4. 7, and an on-off solenoid valve 14 is interposed in this air passage 13. Reference numeral 15 denotes a three-way solenoid valve, which has an atmosphere opening port 15a, a negative pressure inlet port 15b, and a negative pressure outlet port 15c, and the negative pressure inlet port 15b is connected to a fully closed throttle valve via a first negative pressure passage 16. 5, and the negative pressure outlet 15c communicates with the intake passage 7 slightly upstream of the second negative pressure passage 17.
Negative pressure chamber 1 of the diaphragm device 12a via
2b. Reference numeral 18 denotes a control box, which is connected to the opening/closing solenoid valve 14 through a first output circuit 18a and to the three-way solenoid valve 15 through a second output circuit 18b, into which the engine cold signal X is input. When this occurs, both the open/close solenoid valve 14 and the three-way solenoid valve 15 are energized, and when the engine high-speed rotation signal Y or the transmission high-speed range use signal Z is input, only the three-way solenoid valve 15 is energized to introduce negative pressure. Port 15b and negative pressure outlet 15
Communication with c is now cut off.

In the above structure, control box 1
If none of the engine cold signal opens the air passage 13, while the negative pressure inlet 15b and negative pressure outlet 15c of the three-way solenoid valve 15 communicate with each other, and the negative pressure in the intake passage 7 flows through the first negative pressure passage 16, the three-way solenoid valve 15, and the negative pressure outlet 15c. 2 Negative pressure passage 17
The exhaust gas is introduced into the negative pressure chamber 12b of the flow control valve 12 through the flow control valve 12, and the valve 12c of the flow control valve 12 opens the exhaust gas recirculation passage 11. Therefore, the exhaust gas is returned to the intake passage 7 as indicated by arrow A, but air from the air passage 13 is blocked by the pressure of the exhaust gas, forming a relatively rich air-fuel mixture.

In addition, the engine high speed rotation signal Y or the transmission high speed range use signal Z is sent to the control box 18.
When inputted, the three-way solenoid valve 15 is energized and communication between the negative pressure inlet 15b and the negative pressure outlet 15c is cut off, and the atmosphere opening port 15a and the negative pressure outlet 15c are communicated with each other. As a result, atmospheric pressure is introduced into the negative pressure chamber 12b of the flow control valve 12, and the valve 12c of the flow control valve 12 closes the exhaust gas recirculation passage 11. Therefore, the recirculation of exhaust gas is stopped, and air flows through the air passage 13 in the direction of arrow B, forming a relatively lean air-fuel mixture.

Furthermore, when the engine cold signal
is closed. Therefore, even if the engine valve 2 is opened in a semi-warmed state before the engine warm-up is completed when the engine is cold, air does not flow through the air passage 13, so the air-fuel mixture is not diluted beyond the required air-fuel ratio. Never.

In the second embodiment shown in FIG. 2, in the air passage 13,
A diaphragm valve 19 is provided in place of the on-off solenoid valve 14 of the first embodiment, and a third
The first negative pressure passage 16 via the negative pressure passage 20,
Further, the air cleaners 22 are communicated with each other via atmospheric pressure passages 21, and an intake temperature sensitive valve 23 is provided at the open end of the atmospheric pressure passages 21 in the air cleaners 22. The intake temperature-sensitive valve 23 is set to open the open end of the atmospheric pressure passage 21 when the engine is cold, so when the engine is cold, the air cleaner 22
The atmospheric pressure inside is introduced into the negative pressure chamber 19a of the diaphragm valve 19 through the atmospheric pressure passage 21, and the diaphragm valve 19 closes the air passage 13. On the other hand, during exhaust gas recirculation and in a predetermined operating range after engine warm-up is completed, the intake temperature-sensitive valve 23 is connected to the atmospheric pressure passage 2.
Since the first opening end is closed, the negative pressure in the intake passage 7 is
The air is introduced into the negative pressure chamber 19a of the diaphragm valve 19 via the negative pressure passage 16 and the third negative pressure passage 20, and the diaphragm valve 19 opens the air passage 13. In addition,
In FIG. 2, the same parts as in FIG. 1 are given the same reference numerals, and their explanations are omitted.

As explained above, this idea provides an exhaust gas recirculation passageway with one end opening into the engine's exhaust system and the other end opening into the intake passageway between the carburetor bench lily and the throttle valve. A flow control valve is provided that closes the exhaust gas recirculation passage in the required operating range after engine warm-up is completed, while a check valve with one end open to the exhaust gas recirculation passage downstream of the flow control valve and the other end fully closed. In an engine exhaust gas recirculation device that has an air passage that opens into the intake passage downstream and upstream of the bench lily,
Since the air passage is provided with a valve device that closes the air passage when the engine is cold, the air-fuel mixture will not become leaner than the required air-fuel ratio when the chioke valve is opened in a semi-warmed state. Combustibility is ensured and running performance in a semi-warmed state is improved.

[Brief explanation of the drawing]

Figure 1 is a system diagram of the first embodiment of this invention;
The figure is a system diagram of the second embodiment. 1: Carburetor, 2: Chiyoke valve, 4: Bench lily, 5: Throttle valve, 7: Intake passage, 8: Engine,
9: exhaust pipe, 11: exhaust gas recirculation passage, 12: flow control valve, 13: air passage, 14: opening/closing solenoid valve (valve device), 19: diaphragm valve (valve device).

Claims (1)

[Scope of utility model registration request] An exhaust gas recirculation passage is provided with one end opening into the engine exhaust system and the other end opening into the intake passage between the carburetor bench lily and the throttle valve. A flow control valve that closes the exhaust gas recirculation passage is provided, and one end opens into the exhaust gas recirculation passage downstream of the flow control valve, and the other end opens into the intake passage downstream of the fully closed Chiyork valve and upstream of the vent lily. 1. An exhaust gas recirculation device for an engine having an open air passage, characterized in that the air passage is provided with a valve device that closes the air passage when the engine is cold.