JP2591939Y2 - Exhaust gas purification device for internal combustion engine - Google Patents

Description

[Detailed description of the invention]

[0001]

INVENTION The present invention relates to a device for removing nitrogen oxides contained in the exhaust gas of an internal combustion engine (NO _X).

[0002]

2. Description of the Related Art As a removal means of the NO _X in the gas discharged from an internal combustion engine such as a gasoline engine or a diesel engine, activated alumina (r- alumina) and S ₁ O ₂ and Al
Zeolite-based catalysts synthesized from ₂ O ₃ are known to be effective, and are disclosed, for example, in JP-A-63-283727 and JP-A-3-253713. Zeolite-based catalysts include, for example, mordenite and H-ZSM5.
But are used, the catalyst hydrocarbons (HC) to be effective in substantially equal amounts present and NO _X as NO _X reducing agent. Usually, the amount of HC contained in the exhaust gas is smaller than the amount of NO _X. Therefore, NO _X
In the removing device, an HC adding device is disposed upstream of a catalyst provided in the exhaust pipe, and the HC concentration in the exhaust gas is adjusted to a value at which NO _X is easily reduced. Considering the ease with which HC is vaporized, the position where the HC adding device is disposed is preferably near the exhaust port of the cylinder head where the exhaust gas is heated or upstream of the exhaust manifold.

[0003]

It is desirable that an injector for adding a reducing agent provided in an exhaust pipe is installed as close to an exhaust valve as possible to add the reducing agent to exhaust gas having a high temperature. However, since the exhaust gas flowing into the exhaust pipe contains particulates such as carbon, carbon adheres to the injector provided in the exhaust pipe, causing a poor flow rate adjustment of the additive. In view of the above, the present invention provides an apparatus for providing a heater on the front surface of a nozzle of an injector to combust carbon so as to solve the above-mentioned problem. An apparatus in which a heater is provided at the tip of a nozzle for injecting fuel into a combustion chamber of an internal combustion engine is disclosed in Japanese Patent Application Laid-Open No. 4-103828 to the present applicant. The apparatus of the above publication, the evaporation of fuel, ignition be those that promote, not a device for incinerating carbon or the like deposited on the nozzle of the injector of adding NO _X reducing agent.

[0004]

According to the present invention, as a specific means, a hydrocarbon addition device provided in an exhaust pipe is provided by an injector for injecting hydrocarbon provided in an exhaust manifold, and a fuel passage hole disposed in front of the injector. a heater having a includes a controller for controlling the operation of the injector and the heater.

[0005]

By operating the heater at an appropriate timing, carbon or the like adhering near the nozzle of the injector for adding the reducing agent is incinerated, and clogging of the nozzle is prevented. Therefore, the addition amount of the reducing agent to be precisely controlled, thereby improving the reduction efficiency of NO _X.

[0006]

DETAILED DESCRIPTION FIG. 1 shows an example of the NO _X removal apparatus for an internal combustion engine of the present invention, the cylinder block 10 has a cylinder head 20 corresponding to the number of cylinders, the intake manifold to each cylinder head 20 The 30 intake ports 32 communicate. Fuel is injected into each cylinder head 20 by the main injection device to perform combustion. The exhaust gas after the combustion flows out of the exhaust port 42 to the exhaust manifold 40. The exhaust manifold 40 has branch pipes 40A, 40B, 40C, and 40D branched into the number of cylinders, and each branch pipe is integrated into one exhaust pipe 45. The reduction catalyst 60 is disposed in the middle of the exhaust pipe 45.

[0007] The HC addition device 100 is disposed, for example, at the most upstream portion of the integrated exhaust pipe 45. A temperature sensor 90 is provided at the inlet of the reduction catalyst 60, detects the temperature of exhaust gas flowing into the catalyst 60, and sends the detected temperature to the controller 80 via a line 92. A water temperature gauge 95 is provided on the cylinder block, and sends the temperature of the cooling water to the controller 80 via a line 97. In addition to the cooling water temperature and the exhaust temperature, information on the engine speed N and the engine load L is input to the controller 80.

The HC addition device 100 receives the supply of HC from a dedicated HC tank or a fuel tank 70 of an internal combustion engine, and adds HC to the exhaust manifold 40 via a pipe 115 by an injector provided in the HC addition device. . The HC addition device 100 includes a flow rate control valve, and the opening of the valve is controlled by the controller 80. Controller 8
0 is a line 8 based on information on the engine speed and load.
2 controls the HC injection amount of the injector. EG
The R pipe 50 has a suction port 52 communicating with the exhaust manifold 40 and a discharge port 54 communicating with the intake manifold 30.
And a part of the exhaust gas is returned to the intake system.

FIG. 2 is an explanatory diagram showing details of the HC adding apparatus 100. Mounting boss 45 provided on the pipe wall of exhaust pipe 45
A is provided with a through hole, and the injector 110 is attached. The injector 110 is connected to the fuel tank 70 via a pipe 115. The flow rate of the reducing agent injected from the nozzle 112 of the injector 110 is adjusted by a signal sent from the controller 80 via the line 82.

A heater 140 is provided on the front surface of the nozzle 112 via a packing 130. The heater 140 has a ring shape, and a reducing agent is ejected through a central opening 141. The heater 140 is, for example, an electrothermal type, and is connected to a power supply 150 by harnesses 142 and 144. Holes 46 for passing the harnesses 142 and 144 are formed in the pipe wall of the exhaust pipe 45. The opening and closing of the switch of the power supply 150 is controlled by the controller 80 via the line 152.

The reducing agent injected from the nozzle 112 of the injector 110 is atomized and added to the exhaust gas in the exhaust pipe 45 through the opening 141 of the heater 140. At the start of a cold engine when the cooling water temperature is low, carbon and the like in the exhaust gas easily adhere to the front surface of the nozzle 112 and the like. Controller 80 determines this condition, issues a command to the power supply via line 152, and activates heater 140.

The heater 140 is heated to, for example, about 800 ° C. to incinerate and remove deposits near the front surface of the nozzle 112 of the injector 110. The heater 140 does not need to be operated at all times, and the controller 80 operates the heater only when necessary to save power. The packing 130 interposed between the nozzle 112 and the heater 140 also serves as a heat insulating material. The reducing agent injected from the nozzle is supplied to the heater 14
Since it is heated by 0 to promote atomization, it is uniformly added to the exhaust gas. Thus, also improved reduction efficiency of the NO _X in the catalyst 80.

[0013]

As described above, according to the present invention, a reduction catalyst is disposed in an exhaust pipe of an internal combustion engine, hydrocarbons are added as a reducing agent in an exhaust pipe upstream of the reduction catalyst, and NO in the exhaust gas is reduced.
_In the exhaust gas purifying apparatus for removing _X , the hydrocarbon adding apparatus is constituted by an injector for injecting fuel, and a heater disposed in front of a nozzle of the injector. The heater incinerates and removes deposits such as carbon adhering to the front surface of the nozzle of the injector at a high temperature. As a result, the passage of the nozzle is normally secured, and the correct amount of the reducing agent can be added. Further, since the reducing agent can be heated as required, the atomization situation is also improved. Accordingly, uniformly added in the exhaust gas is improved reduction efficiency of NO _X.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing details of a hydrocarbon addition device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Cylinder block 20 Cylinder head 30 Intake manifold 32 Intake port 40 Exhaust manifold 42 Exhaust port 45 Exhaust pipe 50 EGR pipe 52 EGR intake port 54 EGR discharge port 60 Reduction catalyst 70 Fuel tank 80 Controller 100 HC adding device 110 Injector 112 Nozzle 140 Heater 150 power supply

Claims (1)

(57) [Scope of request for utility model registration] An exhaust pipe connected to an exhaust port of a cylinder block of an internal combustion engine via an exhaust manifold, a reduction catalyst disposed in the exhaust pipe, and a reduction catalyst disposed in the exhaust pipe upstream of the reduction catalyst. An internal combustion engine equipped with a device for adding hydrocarbons to exhaust gas, wherein the hydrocarbon addition device is an injector that injects hydrocarbons provided in an exhaust manifold,
An exhaust gas purification device for an internal combustion engine, comprising: a heater having a fuel passage hole disposed in front of an injector; and a controller for controlling the injection amount of the injector and the operation of the heater in accordance with the operation state of the internal combustion engine. .