JPH06108829A - Exhaust emission control device of internal combustion engine - Google Patents

Abstract

PURPOSE:To improve a supply system for fuel to be added as a reducing agent in an exhaust emission control device of internal combustion engine which is provided with a reducing agent to remove NOX. CONSTITUTION:The fuel in a fuel tank 70 is compressed by a fuel injection pump 150, and is fed to an injection nozzle mounted on a cylinder through an injection pipe. A branch pipe 170 which branches from the injection pipe supplies fuel to an injector 175 mounted on an exhaust pipe 45 as a reducing agent. On the branch pipe, a valve 180 is mounted, which is controlled by a signal from a controller. A controller 80 judges whether a catalyst is in an active condition, including information from an exhaust gas temperature sensor and a catalyst temperature sensor. When the catalyst is in an active condition, the valve 180 is opened through an actuator to inject fuel to the inside of the exhaust pipe 45.

Description

Detailed Description of the Invention

[0001]

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 Activated alumina (r-alumina), S ₁ O ₂ and Al are used as a means for removing NO _x in gases discharged from internal combustion engines such as gasoline engines and diesel engines.
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.
However, this catalyst is effective as a NO _X reducing agent when hydrocarbon (HC) is present in an amount substantially equal to that of NO _X. Usually, the amount of HC contained in the exhaust gas is less than the amount of NO _X. Therefore, NO _X equipped in the internal combustion engine
In the removal device, an HC addition device is provided upstream of the catalyst provided in the exhaust pipe line, and the HC concentration in the exhaust gas is adjusted to a value at which NO _x is easily reduced. Considering the easiness of vaporizing HC, the position of the HC addition device is preferably in the vicinity of the exhaust port of the cylinder head where the exhaust gas has a high temperature or in the upstream position of the exhaust manifold.

[0003]

The pressure of the exhaust gas flowing in the exhaust pipe near the exhaust port is relatively high. Therefore, in order to inject the engine fuel or the like as the reducing agent into the exhaust gas, an injector that generates high pressure is required. For this reason, it is necessary to equip a separate pump for adding the reducing agent, and the apparatus is complicated. For example, Japanese Unexamined Patent Publication No. 4-41917 discloses a device that directly injects fuel from a fuel injection pump into an exhaust pipe. However, in the device of the above-mentioned publication, the fuel injection pump needs to be drastically changed, and the amount of fuel injected into the exhaust pipe is extremely small compared to the amount injected into the cylinder. It is difficult to control the adjustment. The present invention provides an exhaust gas purifying apparatus that solves the above-described conventional problems.

[0004]

An exhaust gas purifying apparatus according to the present invention comprises an injector for adding a reducing agent, which is provided in an exhaust pipe upstream of a reduction catalyst, a branch pipe for connecting an injection pipe and an injector, and a branch pipe. A valve provided in the valve, an actuator that operates the valve, and a controller that controls the actuator. The branch pipe connected to the injector for adding the reducing agent may be connected to a plurality of injection pipes.

[0005]

The injector provided in the exhaust pipe is supplied with fuel from the fuel injection pump, so that the fuel, which is the reducing agent, is injected into the exhaust gas at a sufficient pressure. Since this injection amount is extremely smaller than the amount injected into the cylinder, even if the fuel is distributed as the reducing agent from the injection pipe, the influence is small.

[0006]

DETAILED DESCRIPTION FIG. 1 shows a first embodiment of the NO _X removal apparatus for an internal combustion engine of the present invention, the cylinder block 10
Has cylinder heads 20 corresponding to the number of cylinders, and the intake ports 32 of the intake manifold 30 communicate with each cylinder head 20. Each cylinder head 20 communicates with the exhaust port 42, and the exhaust gas that has completed combustion flows out from the exhaust port 42 to the exhaust manifold 40. The exhaust manifold 40 includes branch pipes 40A, 40B, 40 that are branched according to the number of cylinders.
C and 40D, and each branch pipe is integrated into one exhaust pipe 45. The reduction catalyst 60 is arranged in the conduit of the exhaust pipe 45.

The HC addition device is provided with a fuel tank 7 for an internal combustion engine.
The fuel as a reducing agent is supplied from 0, pressurized by the fuel injection pump 150, sent to the injector 175 through the pipe 170 and the valve 180, and the fuel is injected into the exhaust pipe 45. The controller 80 controls the solenoid valve 182 via the line 82 based on the information on the engine speed and the load. The EGR pipe 50 is the exhaust manifold 40.
Has an intake port 52 communicating with the intake manifold 30 and a discharge port 54 communicating with the intake manifold 30, and recirculates part of the exhaust gas to the intake system.

FIG. 2 is an explanatory view showing the structure of the reducing agent addition apparatus of the present invention. The fuel in the fuel tank 70 is the pipe 7
1 is sucked by the feed pump 100, and the pipe 1
05 is discharged to the fuel filter 110. The fuel filtered by the fuel filter 110 is sent to the fuel injection pump 150 via the pipe 164. The fuel injection pump 150 compresses the fuel into a high pressure and sends it out to the injection pipe 152 which communicates with each cylinder. The tip of the injection pipe 152 has an injection nozzle 16 attached to the combustion chamber of each cylinder.
It is connected to 0, and fuel is injected into the cylinder at a predetermined timing.

Of the fuel sent to the injection nozzle 160, surplus fuel that has not been used for injection is returned to the fuel tank 70 via the overflow pipe 162.
In the apparatus of the present invention, a pipe 170 that branches from one of these injection pipes 152 is provided, and this branch pipe 170 is connected to a reducing agent injector 175 via a valve 180. The injector 175 for injecting the reducing agent is attached to the exhaust pipe 45 and injects the fuel acting as the reducing agent into the exhaust gas G flowing in the exhaust pipe 45.

The valve 180 is opened and closed by an actuator 182, and the actuator 182 receives a command output S ₁ from the controller via a line 82. In the fuel injection pump 150 of the diesel engine, for example, a pump that includes a plunger and pressurizes the fuel to a high pressure is used. In this type of pump, the branch pipe 17
The stroke of the plunger communicating with the injection pipe 152 having 2 is adjusted to increase the fuel discharge amount.
Alternatively, instead of connecting the branch pipe to one injection pipe, the branch pipe may be connected to a plurality of injection pipes.

In any case, the amount of fuel required as the reducing agent is about 2% compared to the amount of fuel injected into the cylinder.
Since it is less than the following, even if the branch pipe is connected to the injection pipe and the branch pipe is opened / closed to execute or stop the addition of the reducing agent, there is no effect on the cylinder side. The fuel injected into the exhaust gas G is vaporized by the temperature of the exhaust gas G, sent to the reducing catalyst 60, reducing the NO _X in the presence of a catalyst, is removed.

FIG. 3 shows a second embodiment of the present invention. In the device of the present embodiment, the temperature state of the engine is detected, and in the exhaust pipe 45, an exhaust gas temperature sensor 83 for measuring the temperature of the exhaust gas G, and a catalyst for measuring the temperature of the reduction catalyst 60. A temperature sensor 84 is provided. In addition, the cylinder block 10 is provided with a cooling water temperature sensor 86 that measures the temperature of the cooling water. The measurement information of these temperature sensors is sent to the controller 80 via each line. The controller 80 determines whether or not the conditions for activating the reduction catalyst 60 are satisfied based on the temperature information. The determination result is output to the actuator 182 via the line 82 to control the opening / closing of the valve 180. In this device, the valve 180 is opened to inject the fuel into the exhaust pipe 45 only under the condition that the reduction catalyst 60 is activated. When the catalyst is inactive, the valve 180 is closed to cut off the fuel injection, so that the fuel is not discharged to the atmosphere together with the exhaust gas.

[0013]

As described above, according to the present invention, in the exhaust gas purifying apparatus including the reducing catalyst provided in the exhaust system of the engine and the injector for injecting the fuel as the reducing agent into the exhaust pipe, A branch pipe is connected to an injection pipe connecting a discharge side and a fuel injection injector attached to a cylinder, and a reducing agent addition injector attached to an exhaust pipe is connected to a tip of the branch pipe. Therefore, the fuel that is the reducing agent can be injected into the exhaust pipe having a high internal pressure at a sufficient pressure. Further, a separate pressurizing pump for injecting the reducing agent is not required, and the device configuration is simplified. Further, since the branch pipe is provided with an opening / closing valve and opened / closed according to an instruction from the controller, fuel can be added into the exhaust pipe only when necessary. Furthermore, a temperature sensor is provided in the exhaust pipe and the reduction catalyst, and the controller determines the activation state of the catalyst based on this information. When the controller determines that the catalyst is activated, it activates the actuator to open the valve. Therefore, when the catalyst is in the inactive state, the fuel is not injected into the exhaust pipe, and it is possible to prevent the fuel from being discharged to the atmosphere together with the exhaust gas.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram of a main part.

FIG. 3 is an explanatory view showing another embodiment of the present invention.

[Explanation of symbols]

 10 Cylinder Block 20 Cylinder Head 30 Intake Manifold 32 Intake Port 40 Exhaust Manifold 42 Exhaust Port 45 Exhaust Pipe 60 Reduction Catalyst 70 Fuel Tank 80 Controller 150 Fuel Injection Pump 152 Injection Pipe 160 Fuel Injection Nozzle 170 Branch Pipe 175 Injector 180 Valve 182 Actuator

Claims (3)

[Claims] 1. An injection nozzle provided in a cylinder of an internal combustion engine, a fuel injection pump for pressure-feeding fuel to the injection nozzle via an injection pipe, and a reduction catalyst provided in an exhaust pipe of the internal combustion engine. In an internal combustion engine, an injector for adding a reducing agent, which is provided in an exhaust pipe upstream of a reduction catalyst, a branch pipe that connects the injection pipe and the injector, a valve provided in the branch pipe, an actuator that operates the valve, and an actuator. An exhaust gas purifying apparatus for an internal combustion engine, comprising: 2. An injection nozzle provided in a cylinder of an internal combustion engine, a fuel injection pump for pressure-feeding fuel to the injection nozzle via an injection pipe, and a reduction catalyst provided in an exhaust pipe of the internal combustion engine. In an internal combustion engine, an injector for reducing agent addition, which is provided in an exhaust pipe upstream of a reduction catalyst, a branch pipe that connects the injection pipe and the injector, a valve provided in the branch pipe, an actuator that operates the valve, and an exhaust gas. An internal combustion engine provided with an exhaust gas temperature sensor provided in a pipe for measuring an exhaust gas temperature, a reduction catalyst temperature sensor for measuring a temperature of a reduction catalyst, and a controller for controlling an actuator based on information from the temperature sensor. Exhaust gas purification device. 3. The exhaust gas purifying apparatus for an internal combustion engine according to claim 1, wherein a branch pipe connected to an injector for adding a reducing agent is connected to a plurality of injection pipes.