JPH0615859B2 - Exhaust gas reduction device for engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of an exhaust gas recirculation device for an engine.

(Prior Art) The engine removes harmful components such as NOx contained in the exhaust gas by sucking the exhaust gas into the cylinder and reducing the exhaust gas in the intake process of the cylinder according to the rotational speed and the load, This is usually EGR (exhaust gas reduction)
It is called a function. In general, an exhaust gas reduction device includes a reduction passage connected to an engine exhaust pipe, a nozzle connected to the reduction passage via a solenoid valve to supply exhaust gas from the exhaust pipe to an engine intake system, and an engine speed. And a control means for opening the solenoid valve according to the load. In this type of conventional device, the nozzle was a nozzle dedicated to the EGR function, so carbon is likely to adhere to the on-off valve in this nozzle, especially to its valve seat, which causes the valve seat to corrode and effectively exert the EGR function. There was a drawback that I could not do it. Therefore, it is conceivable to add cleaning means for the nozzle, but this is not preferable because it complicates the apparatus and makes it expensive. Further, in the related art, since the exhaust gas for reducing the exhaust gas is supplied in the middle of the intake system, there is a possibility that the EGR concentration varies among the cylinders.

(Object of the Invention) An object of the present invention is to effectively remove carbon that tends to adhere to the nozzle during exhaust gas reduction without adding special means, and also to cause variations in exhaust gas reduction concentration. Therefore, it is an object of the present invention to provide an exhaust gas reduction device for an engine that can maintain the EGR function for a long period of time.

(Structure of the Invention) An exhaust gas reducing apparatus for an engine according to the present invention includes a reducing passage connected to an exhaust pipe of an engine, and an exhaust gas from the exhaust pipe connected to the reducing passage via a solenoid valve to an intake system of the engine. It consists of a nozzle to supply and control means to open the solenoid valve according to the engine speed and load.
This exhaust gas reduction nozzle also serves as an air injection nozzle that blows high-pressure air directly from the high-pressure air supply source into the cylinder of the engine when starting and accelerating, and the solenoid valve uses this air-injection nozzle as a reduction passage and a high-pressure air supply source. It is a three-way valve for switching to and, and the control means controls to switch the three-way valve in response to exhaust gas reduction when blowing exhaust gas into the cylinder and start and acceleration when blowing high-pressure air into the cylinder. I am trying.

According to this structure, the air injection nozzle can inject high-pressure air at the time of starting and accelerating the vehicle by the control means, but since this air injection nozzle also serves as a nozzle for exhaust gas reduction, the EGR mode The exhaust gas introduced from the exhaust pipe can be injected into the cylinder to reduce the exhaust gas. Therefore, it is understood that the carbon that tends to be deposited on the air injection nozzle in the EGR mode can be cleaned when the high pressure air is injected and the durability of the nozzle can be improved, so that the EGR function is not deteriorated. Further, since the nozzle serves both for exhaust gas reduction and for starting acceleration in this way, and no cleaning means for the exhaust gas reducing nozzle is particularly required, an exhaust gas reducing device and an air supply system for starting acceleration are also required. This is extremely economical as compared to the case where the and are separately provided, because the device is significantly simplified.

Furthermore, during exhaust gas reduction (EGR), the exhaust gas is blown directly into the cylinders of the engine, not in the middle of the intake system, so there is no variation in EGR concentration between cylinders, and a good EGR function is achieved. You can

(Embodiment) An embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 and FIG. 2 show an exhaust gas reduction apparatus 10 for an engine according to the present invention. The return passage 16 connected to the exhaust pipe 14 of the engine 12 and the return passage 16 via the solenoid valve 18
The nozzle 22 that blows the exhaust gas from the exhaust pipe 14 into the cylinder 20 of the engine 12 and the engine 12
Control means 2 for opening the solenoid valve 18 according to the rotation speed and load of the
It consists of 4 and.

In the exhaust gas reduction device 10 of the present invention, the exhaust gas reduction nozzle 22 also serves as an air injection nozzle 22A for directly injecting high pressure air from the high pressure air supply source 26 into the cylinder 20 at the time of starting and accelerating. The solenoid valve 18 is composed of a three-way valve 18A that switches the air injection nozzle 22A to the return passage 16 and the high pressure air supply source 26. The high pressure air supply source 26 comprises an air tank 30 in which high pressure air is stored by a compressor 28. The control means 24 responds to the exhaust gas returning to the cylinder 20 and the high-pressure air to the cylinder for starting and accelerating.
Control to switch 8A. This control means 24 is
For example, engine speed N, vehicle speed V, accelerator opening O,
It comprises a computer 32 which receives the factor signal of the transmission position T / M and judges the exhaust gas reduction mode EGR and the start acceleration mode AC. In the illustrated embodiment, the exhaust pipe 14 has a butterfly valve 34 that closes the exhaust pipe 14 on the downstream side of the return passage 16. The butterfly valve 34 is used when the computer 32 determines the exhaust gas reduction mode EGR. It is driven by the air cylinder 36 so as to close. The air cylinder 36 is controlled by a check valve 38 so as to be activated by the high pressure air supplied from the air tank 30.

As shown in FIG. 3, the air injection nozzle 22A has a poppet valve 42 which is opened and closed by a solenoid 40, and the solenoid 40 is excited when the mode EGR or AC is judged and the poppet valve 42 is opened. Control to open.

Next, the operation of the apparatus of the present invention will be described.
When 2 determines the start acceleration mode AC, the three-way valve 18A is switched to the air tank 30th speed, and when the cylinder 20 enters the intake stroke, the intake valve (not shown) is closed and the solenoid 40 of the air injection nozzle 22A is excited to activate the poppet. Valve 42
open. Therefore, the high-pressure air is sucked into the cylinder 20 from the air tank 30 through the three-way valve 18A to improve ηυ, and together with the fuel injection amount, the torque at the time of start and low-speed acceleration is increased. When the computer 32 determines the exhaust gas reduction mode EGR, the three-way valve 18
By switching A to the return passage 16 side, the solenoid 40 of the air injection nozzle 22A is excited in the intake stroke to open the poppet valve 42. Therefore, the exhaust gas is sucked into the cylinder 20 from the exhaust pipe 14 through the reduction passage 16 and the three-way valve 18A to reduce the exhaust gas. At this time, since the butterfly valve 34 is closed, the exhaust gas has a high pressure at the inlet of the reducing passage 16 and the amount of reduction of the exhaust gas increases. In this exhaust gas reduction mode EGR, carbon tends to deposit on the valve seat of the poppet valve 42, but this carbon is cleaned when high pressure air is injected from the air injection nozzle 22A in the start acceleration mode AC.

(Effects of the Invention) According to the present invention, as described above, the air injection nozzle can inject high-pressure air at the time of starting and accelerating the vehicle by the control means. In the EGR mode, the exhaust gas introduced from the exhaust pipe can be injected into the cylinder to reduce the exhaust gas. Therefore, carbon that tends to be deposited on the air injection nozzle in the EGR mode can be cleaned when the high pressure air is injected and the durability of the nozzle can be improved, so that the EGR function is not deteriorated. In addition, since the nozzle partially shares both systems for both exhaust gas reduction and start acceleration in this way, and no special cleaning means for the exhaust gas reduction nozzle is required, the overall system is significantly improved. Simplified and extremely economical.

Further, during exhaust gas reduction (EGR), the exhaust gas blows directly into the cylinders of the engine, not in the middle of the intake system, so there is no variation in EGR concentration between cylinders, and a good EGR function is achieved. You can

[Brief description of drawings]

1 and 2 are a front view and a schematic side view of an exhaust gas reduction device for an engine according to the present invention, and FIG. 3 is an enlarged sectional view of an air injection nozzle. 10 ... Engine exhaust gas reduction device, 12 ... Engine, 14 ... Exhaust pipe, 16 ... Reduction passage, 18 ...
Solenoid valve, 18A ... 3-way valve, 20 ... Cylinder, 22 ...
... Nozzle, 22A ... air injection nozzle, 24 ... control means, 26 ... high-pressure air supply source.

Claims (1)

[Claims] 1. A reduction passage connected to an exhaust pipe of an engine, a nozzle connected to the reduction passage via a solenoid valve for supplying exhaust gas from the exhaust pipe to an intake system of the engine, and a rotation speed of the engine. In an exhaust gas reduction device for an engine, which comprises a control means for opening the solenoid valve according to a load, the nozzle also serves as an air injection nozzle for directly injecting high pressure air from a high pressure air supply source into a cylinder of the engine at the time of starting and accelerating. The solenoid valve is a three-way valve that switches the air injection nozzle between the reducing passage and the high-pressure air supply source, and the control means controls the exhaust gas when the exhaust gas is blown into the cylinder and the high-pressure air. Exhaust gas reducing apparatus for an engine, characterized in that the three-way valve is controlled so as to be switched depending on when the vehicle is started and accelerated. .