JPS626281Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an exhaust gas recirculation device for a vehicle internal combustion engine, and particularly to one that aims to improve exhaust gas recirculation performance in a high load region.

[Conventional technology]

In the past, many proposals have been made for such exhaust gas recirculation devices, and one method for effectively recirculating exhaust gas including in a high load region is the use of a throttle valve as in Japanese Utility Model Application Publication No. 49-30724. Some use negative pressure immediately upstream of a fully closed valve and ventilator negative pressure.

By the way, in recent years, unlike the method described in the above publication that directly operates the EGR valve using the negative pressure extracted from the carburetor, a microcomputer has been used to detect the engine operating status and optimally control the EGR amount. There is. One way to do this is to adjust the suction pipe negative pressure to always maintain a constant negative pressure, and then control this negative pressure using a microcomputer according to the engine operating status.
There are things that act on valves.

However, since this conventional example uses only suction pipe negative pressure, in the high load region near full throttle opening, the negative pressure for controlling the EGR valve becomes the same as the suction pipe negative pressure, making it difficult to open the EGR valve sufficiently. I can't. Therefore, there is a drawback that the amount of EGR is insufficient during high loads when the amount of EGR needs to be increased, and it is not possible to sufficiently reduce the amount of MOx that is emitted in large amounts.

However, examples of prior art useful for solving this drawback include Japanese Patent Application Laid-Open No. 54-98423 and Japanese Patent Publication No. 52-13263.
These exhaust gas recirculation paths include negative pressure in the suction pipe, the atmosphere for leaking the negative pressure, negative pressure in the bench lily, and exhaust gas through the orifice. There are three chambers into which negative pressure is introduced separately: bench lily negative pressure, atmospheric pressure,
Three chambers into which suction pipe negative pressure is introduced are each separated by a diaphragm. A pressure regulating device is provided.

[Problem that the invention attempts to solve]

Therefore, according to the above-mentioned prior art example, the pressure regulating device has three chambers each partitioned by two diaphragms, resulting in a problem that the structure is complicated.

[Means for solving problems]

The present invention aims to solve such problems and has the following technical means. In other words, in an exhaust gas recirculation system that communicates an exhaust gas recirculation path with an EGR valve from the exhaust system of the engine body to the intake system, a diaphragm is used to connect the negative pressure passage that leads to the suction pipe negative pressure and the negative pressure passage that leads to the ventilator negative pressure. It communicates with the negative pressure chamber of the pressure regulating device, which is divided into an atmospheric chamber and a negative pressure chamber, and each of these chambers is equipped with a spring, with the spring force on the negative pressure chamber side being larger than that on the atmospheric chamber side. The negative pressure inlet port of the negative pressure passage for introducing the negative pressure in the suction pipe is provided close to and opposite to the diaphragm, and the negative pressure passage from the pressure regulator is connected to the negative pressure according to the engine operating state. The valve is connected to a solenoid valve that leaks water and a negative pressure chamber for controlling the EGR valve.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. In FIG. From the suction pipe 2 as well known as EGR
An exhaust gas recirculation passage 6 having a valve 5 is configured to communicate with the exhaust gas.

In order to control the negative pressure in the negative pressure chamber 7 of the EGR valve 5, first, a pressure regulator 8 is provided to ensure sufficient EGR valve control negative pressure in the entire load range from low load to high load. This pressure regulator 8 includes an atmospheric chamber 10 and a negative pressure chamber 11 divided by a diaphragm 9.
The diaphragm 9 is biased by springs 12 and 13 in each of these chambers 10 and 11, respectively.
There are two negative pressure inlet ports 14 , 15 and one outlet port 16 in the negative pressure chamber 11 . The port 14 communicates with the suction pipe 2 through a negative pressure passage 17 to introduce suction pipe negative pressure, and the port 15 communicates with the intake pipe 2 through a negative pressure passage 18 on the upstream side of the throttle valve 19 of the carburetor 3.
Port 14 of these ports is provided close to and facing the diaphragm 9, and when the suction pipe negative pressure or the ventilate negative pressure is large, the diaphragm 9 is The deflection directly closes the port 14. On the other hand, the port 16 communicates with the negative pressure control unit 22 and the negative pressure chamber 7 of the EGR valve 5 through a negative pressure passage 21, and the pressure regulator 8 of each of these negative pressure passages 17, 18, 21
An orifice 23 is provided on each side.

The negative pressure control unit 22 includes a solenoid valve 24 provided in the passage 21 to leak the negative pressure to the atmosphere.
Solenoid valve 2 is activated by sensing water temperature and throttle valve opening to detect engine operating status.
4 opening time ratio (hereinafter referred to as duty ratio)
It consists of a control unit 25 that changes the solenoid valve 2 by such a control unit 25.
The negative pressure in the negative pressure chamber 7 of the EGR valve 5 is controlled by the negative pressure leak operation 4.

To explain the operation of the exhaust gas recirculation device of the present invention configured as described above, the vent lily negative pressure is small during idling, low load, and medium load.
Furthermore, since the spring force of the spring 13 provided in the pressure regulating device 8 is set to be stronger than the spring force of the spring 12, the suction pipe negative pressure is regulated and the negative pressure passage 21
A substantially constant negative pressure can be obtained. Therefore, if the engine is cold at this time, a large amount of negative pressure will be leaked by the solenoid valve 24 due to a signal with a large duty ratio from the control unit 25 in the negative pressure control section 22, and the opening degree of the EGR valve 5 will be 0 or small. The exhaust gas recirculation amount is set to 0 or a small amount. On the other hand, when the load is medium or the engine is warmed up, the amount of negative pressure leaked is controlled by the solenoid valve 24, and the negative pressure in the negative pressure chamber 7 of the EGR valve 5 increases.
The opening degree of the EGR valve 5 is also increased to recirculate a large amount of exhaust gas.

When the throttle valve 19 is substantially fully opened during high load, the suction pipe negative pressure itself decreases, making it impossible to secure sufficient negative pressure in the negative pressure chamber 11 of the pressure regulating device 8 by itself. By the way, in such an operating range, air passes through the ventilator 20 of the carburetor 3 at high speed, creating a large ventilator negative pressure there, and this ventilator negative pressure is introduced into the negative pressure chamber 11 of the pressure regulator 8. Ru. Therefore, since the port 14 is closed by the diaphragm 9, the negative pressure in the negative pressure passage downstream of the negative pressure chamber 11, the negative pressure chamber 7, etc. is higher than the suction pipe negative pressure shown by the solid line, as shown by the broken line in FIG.
EGR valve control negative pressure will be ensured.
Therefore, if the negative pressure control section 22 is controlled to increase the amount of exhaust gas recirculation at this time, the EGR valve 5
The opening operation is quick and reliable, and a large amount of exhaust gas is recirculated.

[Effect of idea]

As is clear from the above description, according to the present invention, a large amount of exhaust gas is recirculated during high load near the fully open throttle valve, so that it is possible to effectively reduce the amount of NOx that is emitted in large amounts at this time. The ventilator negative pressure that generates high negative pressure at high loads is used, and by simply adding a ventilator negative pressure line, it can be controlled in the same way as other operating areas, and the pressure regulating device is different from the prior art example described above. Since two chambers separated by one diaphragm are sufficient, the structure is simple and compact. Furthermore, at high loads, sufficient negative pressure is secured and the EGR valve 5 is operated to fully open, so the EGR valve 5 has a smooth opening area characteristic with respect to the control negative pressure.
EGR flow rate can be controlled with high precision.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the device according to the present invention, and FIG. 2 is a diagram showing the relationship between negative pressure and throttle opening in the case of the present invention. 1... Engine body, 2... Intake pipe, 3... Carburetor, 4... Exhaust pipe, 5... EGR valve, 6...
Exhaust gas recirculation path, 7... Negative pressure chamber, 8... Pressure regulator, 12, 13... Spring, 17, 18, 21...
Negative pressure passage, 24...Solenoid valve.

Claims (1)

[Scope of utility model registration request] In an exhaust gas recirculation system that communicates an exhaust gas recirculation path with an EGR valve from the exhaust system of the engine body to the intake system, a diaphragm connects the negative pressure path that leads to the suction pipe negative pressure and the negative pressure path that leads to the ventilator negative pressure to the atmosphere. It communicates with the negative pressure chamber of the pressure regulating device, which is divided into a chamber and a negative pressure chamber, and each of these chambers is equipped with a spring, with the spring force on the negative pressure chamber side being larger than that on the atmospheric chamber side. The negative pressure inlet port of the negative pressure passage for introducing the suction pipe negative pressure is provided in close proximity to the diaphragm, and the negative pressure passage from the pressure regulating device is configured to introduce negative pressure according to the engine operating state. An exhaust gas recirculation device, characterized in that it communicates with a solenoid valve to be leaked and a negative pressure chamber for controlling the EGR valve.