JPH0519528Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an exhaust treatment device that separates and burns particulates in exhaust gas discharged from an internal combustion engine.

(Prior Art) Exhaust from an internal combustion engine, particularly a diesel engine, contains fine particles mainly consisting of carbon particles, and it is necessary to separate and remove them. However, the particle size of the fine particles is on the order of submicrons, and the method using ordinary materials causes premature clogging, making it unsuitable for permanent use. Therefore,
An exhaust gas treatment device has been proposed that regenerates materials by periodically burning captured particulates.
As an example, as shown in Japanese Patent Application Laid-Open No. 58-180711, a filter made of ceramic supporting a catalyst is disposed in the exhaust pipe, and a fuel injection nozzle is provided upstream of the filter. Some filters capture particulates and when the filter becomes clogged, fuel is injected toward the filter to burn the particulates.

(The problem that the invention aims to solve) However, at low temperatures, the fuel injected from the nozzle is cold and is injected before it is sufficiently atomized, resulting in fuel particles adhering to the surface of the filter, causing the catalyst to oxidize. The reaction may not occur and the combustion of the particulates may be delayed or the filter may cause abnormal combustion. In addition, the fuel dripping from the nozzle accumulates at the bottom of the exhaust pipe, increasing fuel consumption.
The problem is that it evaporates due to the heat of the exhaust gas and reacts with the catalyst, causing combustion even when the filter is not clogged.

(Means for solving the problem) The present invention places a housing in the middle of the exhaust pipe,
A filter supporting a catalyst is disposed in the housing, and a box-shaped fuel evaporator with a flow port on the top surface is disposed in the center of the upstream side of the filter, communicating with the fuel tank via a pressure pump. A control device is provided to operate the pressure pump when the pump reaches a predetermined clogging state.

(Function) When the filter becomes clogged, the fuel sent from the fuel tank by the operation of the pressure pump is stored in the fuel evaporator, is heated by the heat of the exhaust gas, becomes vaporized, becomes gaseous, mixes with the flow of exhaust gas, and flows through the filter. uniformly reach the entire surface. The particulates captured by the filter are ignited and burned by the heat generated by the oxidation reaction between the gaseous fuel and the catalyst.

(Embodiment) FIG. 1 shows an exhaust treatment device 1 according to the present invention, which includes a filter 2, a fuel evaporator 7, and a control device 13. The filter 2 is housed in a housing 4 placed in the middle of the exhaust pipe 3, and is generally referred to as a wall flow type filter. 5 is provided, and the chamber wall 6 of the overchamber 5 is used as a passage surface. The chamber wall 6 is impregnated with a catalyst such as a noble metal such as platinum or rhodium. A fuel evaporator 7 is disposed on the upstream side of the filter 2 and in the center with respect to the cross section of the housing in the direction perpendicular to the exhaust gas flow. The fuel evaporator 7 has a box shape made of stainless steel material with excellent heat resistance, and has an inlet pipe 8 on one side wall that communicates with the fuel tank 10.
is provided, and a large number of flow ports 9 are provided on the upper surface through which the gaseous fuel passes. An inlet pipe 8 of the fuel evaporator 7 and a fuel tank 10 are communicated with each other via a pressure pump 11 through a conduit. Exhaust pressure sensing sensors 12 are provided on both sides of the filter 2 to detect a differential pressure across the filter 2, and are connected to the control device 13 together with the pressure pump 11.

When the engine is operated, the exhaust gas flows into the housing 4, and the filter 2 traps and filters out particulates. Exhaust gas containing fine particles flows into the chamber 5 from the inlet face of the filter 2, and when passing through the chamber wall 6 of the chamber 5, the fine particles are separated into the chamber wall 6. When the filter 2 reaches a predetermined clogging state, the exhaust pressure sensor 12
supplies information to the control device 13, which in turn operates the pressure pump 11 to send the fuel in the fuel tank 10 to the fuel evaporator 7 and store it in its box. The exhaust heat heats the fuel evaporator 7 and vaporizes the fuel, and the vapor exits from the flow port 9, mixes with the exhaust flow, reaches the filter 2, and reacts with the catalyst impregnated in the chamber wall 6 of the filter 2. Oxidation reaction generates heat and burns particulates.

In another embodiment, as shown in FIG. 3 as a fuel evaporator, a tray 21 having a flat or round shape and an open top is supported in multiple stages by stays 22, and a pressure pump 11 is mounted on the top of the tray 21. A fuel evaporator 20 is provided in front of the filter 2 and is connected to a fuel evaporator 20 with a conduit connected to the fuel evaporator 2 and provided with a port 23 on the lower surface of each stage.

(Effects of the invention) As described above, the present invention has a catalyst-carrying filter that is located upstream of the filter that carries the catalyst and at the center of the cross section of the housing.
A fuel evaporator is installed, which is a box-shaped container that communicates with the fuel tank and has a flow port on the top surface.When the filter is clogged, the fuel vaporized from the fuel evaporator is mixed with the exhaust gas, and the fuel is mixed with the catalyst. Since the oxidation reaction is caused, the fuel becomes atomized and is sprayed over the entire surface of the filter, so that the oxidation reaction with the catalyst takes place evenly, and as a result, the particulates collected on the filter are completely burned and removed. . In addition, fuel does not vaporize until the exhaust gas temperature rises sufficiently.
When the temperature of the exhaust gas increases, vaporization is promoted, and the fuel does not stick to the filter part in a liquid state or stay inside the housing, which prevents the next ignition, increases fuel consumption, and corrodes the housing. etc. does not result.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the exhaust treatment device of the present invention, FIG. 2 is a perspective view of a fuel evaporator, and FIG. 3 is a sectional view of another embodiment of the fuel evaporator. 1...Exhaust treatment device, 2...Filter, 3...
Exhaust pipe, 7, 20... Fuel evaporator, 8... Inlet pipe, 9... Distribution port, 10... Fuel tank, 11
...pressure pump, 13 ... control device, 21 ... saucer.

Claims (1)

[Scope of utility model registration request] A housing is placed in the middle of the exhaust pipe, a filter carrying a catalyst is placed inside the housing, and an inlet pipe is provided on one side on the upstream side of the filter and in the center of the cross section of the housing. In addition to arranging a box-shaped fuel evaporator with an opening,
An exhaust gas treatment for an internal combustion engine, comprising: a control device that connects the inlet pipe to a fuel tank via a pressure pump, and controls the pressure pump to operate when the filter reaches a predetermined clogging state. Device.