JPS5852353Y2 - Exhaust gas recirculation device - Google Patents

Description

[Detailed description of the invention] This invention reduces nitrogen oxides (hereinafter referred to as NOx) in the exhaust gas by circulating a part of the exhaust gas back into the intake system.
This invention relates to an exhaust gas recirculation device for automobile diesel engines that reduces the concentration of exhaust gas.

In the past, various systems have been researched and commercialized as exhaust gas recirculation devices for automobiles, but as NOx regulations become stricter, exhaust gas recirculation devices are also required for diesel vehicles.

What is shown in FIGS. 1 and 2 is a conventional device.

The outline of this exhaust gas recirculation device will be explained.

Exhaust gas passes through the exhaust gas port 8, the valve 11 in the exhaust gas regulating valve 2, and the exhaust gas port 9, and is led to the intake passage 7.

Note that the flow rate of the exhaust gas is controlled by the controlled negative pressure in the controlled negative pressure chamber 13 via the diaphragm 12 .

On the other hand, the intake air passes through the passage 6, passes through the valve 10 for generating negative pressure in the exhaust gas passage T, and guides the exhaust gas from the exhaust port 9, and then flows into the intake passage 7. and is sent into the engine.

As a result, the combustion temperature of the engine decreases due to the recirculated exhaust gas, and the NOx concentration in the exhaust gas decreases.

By the way, the lever 3 and the valve 10 are directly connected.

The relationship between the angle θ of the lever 3 and the intake air flow rate Qa at this time is indicated by A in FIG.

The intake air amount Qa increases as the lever angle θ increases, but the increase in Qa is particularly significant in the low opening range of the lever angle θ.The negative pressure generated in the intake passage γ increases as the intake air amount Qa increases. Because of its tendency to decrease, the negative pressure within the intake passage T rapidly decreases when the valve begins to open.

This makes it impossible to draw out the required amount of exhaust gas from the exhaust gas port 9 and recirculate it into the intake air.

Therefore, a problem arose in that the combustion temperature rose and NOx could not be reduced.

This invention reduces the negative pressure in the intake passage to reduce the amount of EGR when the engine is characterized by power, and at other times generates sufficient negative pressure in the intake passage to achieve the required EGR.
The objective is to obtain an exhaust gas recirculation device that can obtain a GR amount.

For the above purpose, a structure is adopted in which the valve opening degree gradually increases in a region where the amount of depression of the accelerator pedal is small, and the pulp opens wide when the accelerator pedal is depressed greatly.

Specifically, a first lever is provided on the valve shaft of the throttle valve, a second lever is connected to the accelerator pedal and has a cam surface that contacts the first lever, and rotation of the second lever causes the first lever to move. The lever is rotated, and the cam surface is shaped such that the amount of rotation of the first lever increases rapidly in a region where the rotation angle of the second lever is large.

An embodiment of the present invention will be described with reference to FIGS. 3, 4, and 5.

The flow of exhaust gas for recirculation and the flow of intake air flow are similar to those explained in FIGS. 1 and 2 in the conventional example.

Furthermore, the throttle valve section of the present invention is composed of a pulp section in which a lever 15 is connected to the pulp 10, and a lever 16 which is a throttle section.

A cam surface 16a is formed on the lever 16, and a roller 1T formed at the free end of the lever 15 is in contact with this cam surface.

Further, the cam surface 16a has a shape in which the distance from the center gradually increases as the opening degree of the lever 16 increases, and the distance increases rapidly at a certain angle θ1.

As a result, the opening angle of the valve 10 increases proportionally up to a certain angle θl, and increases rapidly beyond this angle.

Characteristic B in FIG. 5 shows the characteristic at this time.

This characteristic indicates that the intake air flow rate increases proportionally up to the lever angle θ1, and then rapidly increases from θ1.

As a result, up to the lever angle θ1, the amount of intake air is limited compared to conventional products, so sufficient negative pressure is generated downstream of the pulp 10, and the exhaust gas is returned in proportion to the opening degree of the valve 11. The flow rate will be obtained.

This allows the NOx concentration in the exhaust gas to be sufficiently reduced.

In this embodiment, as shown in FIG. 5B, when the lever angle θ reaches a certain value, the QA sharply increases, and the cam surface may be formed to have a quadratic curve characteristic. As described above, according to the present invention, sufficient negative pressure can be obtained downstream of the throttle valve, the required amount of exhaust gas can be recirculated by the exhaust gas regulating valve, and NO in the exhaust gas can be reduced.
It became possible to sufficiently reduce x.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a conventional exhaust gas recirculation device, Fig. 2 is a sectional view thereof, and Fig. 3 is an explanatory diagram of the exhaust gas recirculation device of the present invention.
FIG. 4 is a sectional view thereof, and FIG. 5 is a flow rate characteristic diagram of the conventional exhaust gas recirculation device and the present invention. 2...Exhaust gas adjustment valve, 3...Lever, 7...Intake passage, 9...Exhaust gas port, 10...Pal 7", 11...
Valve, 15... Lever 16... Bent lever
16a...Cam surface, 17...Curved roller.

Claims (1)

[Scope of utility model registration request] The exhaust system and intake system are connected through a conduit so that part of the exhaust gas from the exhaust pipe of the diesel engine is recirculated to the intake system.
In the conduit, an exhaust gas inlet port, a regulating valve, and an exhaust gas outlet port connected to the intake passage of the intake system are provided in order from the exhaust system to the intake system, and the regulating valve is connected to the diaphragm to reduce the negative impact generated in the intake system. The exhaust gas recirculation device controlled by pressure is provided with a valve that generates negative pressure at the exhaust gas outlet port upstream of the exhaust gas outlet port in the intake passage, and a first lever is attached to the valve shaft of the valve. a second lever connected to an accelerator pedal and having a cam surface in contact with the first lever; a mechanism for rotating the first lever by rotation of the second lever; . An exhaust gas recirculation device, characterized in that the amount of rotation of the first lever increases rapidly in a region where the angle of rotation of the second lever is large.