JPS638846Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an EGR device for a diesel engine.

The fact that EGR (exhaust gas recirculation) is effective in suppressing the formation of nitrogen oxides in exhaust gas remains the same in both gasoline engines and diesel engines.

However, in diesel engines,
The exhaust gas contains a large amount of smoke (carbon particles) that is not included in the gasoline engine, so it is necessary to simply extract the exhaust gas from the exhaust system as is used in gasoline engines. If only the gas is returned to the intake system, the carbon particles will accumulate in the gas flow path, control valve, etc., and a predetermined amount of EGR will not be secured in a short period of time. Furthermore, the re-inflow of these carbon particles into the intake system and combustion chamber is undesirable from the viewpoint of the durability of engine cylinders and rings, etc., and results in deterioration of lubricating oil and an increase in blow-by gas. .

Therefore, traditionally, diesel engines
When implementing EGR, attempts have been made to first filter the exhaust gas extracted from the exhaust system with a filter, remove carbon particles therein, and then return it to the intake system. This results in the filter becoming clogged early, necessitating periodic maintenance and inspection or replacement, which is extremely complicated work.

The present invention has been made in view of this point, and it is an object of the present invention to provide an EGR device for a diesel engine that has a purification function that can eliminate the clogging of the filter.

An embodiment of the present invention shown in the drawings will be described below. In Figure 1, 1 is a diesel engine, 2
is its intake system (pipe), 3 is its exhaust system (pipe),
4 and 5 connect this intake pipe and exhaust pipe
This is an EGR passage, and a filtration device 7 including a filter 6 is interposed therebetween.

The filtration device 7 includes a gas inlet 8 and a gas outlet 9 connected to the EGR passages 4 and 5, respectively, and also has a purge gas inlet 10 and a purge gas outlet 11. 11 are orthogonal to each other via a filter 6.

12 is a purge gas introduction pipe, one end of which is connected to the exhaust pipe 3, and the other end is connected to the purge gas inlet 10 and the gas outlet 9. Furthermore, 13 is a return pipe, one end of which communicates with the exhaust pipe 3, and the other end of which communicates with the purge gas outlet 11.

The filter 6 is made of a material such as a wire mesh, for example.
A plurality of gas inlets 8 and gas outlets 9 are connected in the overlapping direction (vertical direction), and a purge gas inlet 10 and a purge gas outlet are connected in the horizontal direction. 11 are connected.

Further, 14 is a control valve disposed in the exhaust pipe 3;
Reference numeral 15 indicates a purge valve provided in the purge gas introduction pipe 12, and reference numeral 16 indicates an EGR valve provided in the EGR passage 5 connected to the intake pipe 2.

In the EGR device of the present invention configured as described above,
EGR is performed and carbon particles attached to the filter are removed in the following manner.

In other words, when performing EGR, first purge valve 1
5 is closed and the control valve 14 and EGR valve 16 are opened. As a result, the exhaust gas flows between the exhaust pipe 3 and the intake pipe 2.
Due to the pressure difference between the two gases, the gas flows as shown by the solid arrow E in the figure, and during that time passes through many meshes of the filter 6, filters out the carbon particles contained therein, becomes clean gas, and is EGRed into the intake pipe.

Further, when removing carbon particles attached to the filter, the control valve 14 and the EGR valve 16 are closed and the purge valve 15 is opened in an operating state where the amount of smoke generated is small, such as during deceleration. As a result, relatively clean exhaust gas with little smoke flows through the purge gas inlet pipe 12 from the gas outlet 9 and the purge gas inlet 10 as indicated by the dotted arrow P in the figure, and blows through from the vertical and horizontal directions of the filter 6. , the carbon particles attached to it are peeled off and the carbon particles are removed from the gas inlet 8 or the purge gas outlet 11.
It flows out into the exhaust pipe 3 via the EGR passage 4 or the return pipe 13.

In this case, since the purge gas blows through the filter 6 both vertically and horizontally, the carbon particles adhering thereto are exfoliated very conveniently.

As shown in FIG. 2, when exhaust gas containing carbon particles (indicated by arrow E') comes into contact with the filter 6, the carbon particles C are mainly deposited on the upstream half of the filter. Therefore, if the purge gas is made to flow only from the direction of the arrow P', the carbon particles C adhering to both side surfaces A and B of the filter 6 will be removed, but the carbon particles C adhering to the sides A and B of the filter 6 will be removed. The carbon particles cannot be exposed to the purge gas flow and cannot be stripped away. However, in this invention, in addition to this purge gas in the direction of arrow P',
Since the purge gas is made to flow down from the P'' direction as well, the carbon particles adhering to the above C are also reliably removed.

As described above, in the device of the present invention, the exhaust gas under operating conditions where the amount of smoke generation is small, such as during deceleration, is used as purge gas to blow onto the filter 6 from two directions, so that the carbon particles attached thereto are blown from two directions. is properly peeled off, the filter can be kept clean at all times, and clogging can be prevented.

Generally, during deceleration, fuel is not injected and the exhaust gas contains almost no nitrogen oxides, so there is no need to perform EGR, and carbon particles are also not included. Since there is no,
It is very convenient to use exhaust gas during deceleration as purge gas.

Note that a shutter is arranged on the side of the filter 6 facing the purge gas inlet 10 and the purge gas outlet 11.
If this is closed during EGR, exhaust gas filtration will be even more effective.

[Brief explanation of the drawing]

FIG. 1 is a partially enlarged cross-sectional explanatory view showing one embodiment of the device of the present invention, and FIG. 2 is an explanatory view showing the state of adhesion of carbon particles. 2; Intake system (pipe), 3; Exhaust system (pipe), 4, 5;
EGR passage, 6; filter, 7; filtration device, 8;
Gas inlet, 9; Gas outlet, 10; Purge gas inlet, 11; Purge gas outlet, 12; Purge gas introduction pipe, 13; Return pipe.

Claims (1)

[Scope of utility model registration request] A filtration device comprising a gas inlet, a gas outlet, a purge gas inlet, a purge gas outlet, and a filter interposed between these, and an EGR that connects the exhaust system of a diesel engine and the gas inlet, and the intake system and the gas outlet. a passage, a purge gas introduction pipe that opens one end to the exhaust system and the other end to the gas outlet and the purge gas inlet, a return pipe that opens one end to the exhaust system and the other end to the purge gas outlet, etc. The carbon particles in the exhaust gas flowing in from the gas inlet are filtered by a filter, and then EGR is performed from the gas outlet, while when non-EGR, exhaust gas is introduced from two directions, the gas outlet and the purge gas inlet, and passes through the filter. An EGR device for a diesel engine, characterized in that the adhering carbon particles can be peeled off and discharged into an exhaust system from a gas inlet and a purge gas outlet.