JPS6038018Y2 - Diesel engine exhaust particulate purification device - Google Patents

Description

[Detailed description of the invention] The present invention relates to an exhaust gas treatment device for a diesel engine, and more specifically, the present invention relates to an exhaust gas treatment device for a diesel engine. The present invention relates to an exhaust particulate purification device suitable for collecting on a collection material, periodically incinerating the collected exhaust particulates, and regenerating the collection material.

Most of these types of exhaust particulates are flammable, such as carbon particles, and these combustible particulates are collected,
Conventionally, there are the following methods for incinerating the collected particles to regenerate the collection material.

(1) A method of throttling the intake system of a diesel engine to reduce the amount of intake air and raise the temperature of exhaust gas to burn exhaust particulates.

(2) A method in which an oil burner is installed in the exhaust system of a diesel engine to raise the temperature of exhaust gas to a temperature at which exhaust particulates are combusted.

(3) A method in which an electric heater is attached to the entire surface of the collection material to burn the exhaust particulates attached to the surface of the collection material, and use this as a heat source to cause the downstream particulates to self-combust.

In any of the above methods, the container side of the trapping material (trap material), that is, the outer peripheral side of the trapping material in the case of axial flow, is cooled by the atmosphere outside the container, and the temperature is lower than that of the center of the trapping material. low.

Therefore, when exhaust particulates are burned, there is a risk that unburned remains may be formed on the outer peripheral portion of the collection material.

Therefore, a method can be considered in which a catalyst is supported on a collection material to promote combustion of exhaust particulates.

However, when a catalyst is supported all around the collection material, the sulfur component in the fuel is discharged as sulfate by the catalyst, which poses a serious problem in terms of environmental health.

An object of the present invention is to provide a diesel engine exhaust particulate purification device that eliminates unburned collected exhaust particulates on the outer periphery of a collection material and minimizes sulfate emissions from a catalyst.

In order to achieve this purpose, the present invention eliminates the unburned remains of exhaust particulates during the regeneration of the waist bucket material that supports the catalyst in the outer peripheral area of the trap material in the direction of the flow of exhaust gas. Reduced sulfate emissions.

In addition, the exhaust particulates accumulated in the collection material are periodically burned and
The means for incineration, ie, the means for regenerating the collection material, may be any means such as throttling, a burner, an electric heater, or a spark that throttles the intake system, or a combination of these may be used.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the following embodiments, a combination of throttling, electric heater, and fuel injection timing control means will be described as a collection material regeneration means.

In FIG. 1, 1 is a diesel engine body, 2 is a cooling fan, 3 is an intake manifold, 4 is an exhaust manifold, 5 is a fuel injection pump, and 6 is a throttle valve provided in an intake passage.

The throttle valve 6 is connected to a negative pressure operated diaphragm valve 9 via a link 8, and the diaphragm valve 9 is connected to a vacuum pump 12 via a negative pressure switching valve 10 and vacuum piping 11.

Further, the negative pressure switching valve 10 is connected to a microcomputer (CPU) 14 via a wiring 13.

Therefore, when a finger cooling signal is input from the CPU 14 to the negative pressure switching valve 10 through the wiring 13, the vacuum path of the negative pressure switching valve 10 opens, and the negative pressure from the vacuum pump 12 is transmitted to the diaphragm valve 9 through the piping 11. and operates the throttle valve 6 in the closing direction via the link 8.

This is the throttle means that throttles the intake passage.

Note that the opening degree of the throttle valve 6 is determined by the throttle sensor 1.
5 and is transmitted to the CPU 14 through the wiring 16.

The fuel injection pump 5 is connected to a fuel injection valve 21 of each cylinder through a fuel pipe 20, and injects fuel into the combustion chamber of the diesel engine.

The fuel injection pump 5 operates a solenoid valve (not shown) in response to a signal transmitted from the CPU 14 through the wiring 22.
This provides means for controlling the fuel injection timing.

Since the specific structure for controlling (retarding) the fuel injection timing is already well known, detailed explanation will be omitted.

In the part of the exhaust pipe immediately downstream of the exhaust manifold 4,
A collection material (trapper container) 30 is attached.

However, the trapper container 30 may be formed integrally with the exhaust manifold 4 by casting so as to be located downstream of the gathering portion of the exhaust manifold 4.

A collection material (trap material) 31 is inside the trapper container 30.
There is (Figure 2).

As the trapping material 31, a known ceramic foam, alumina-coated steel wool, a metal foam filter, or the like can be used.

That is, the trapping material 31 has a three-dimensional mesh structure, through which exhaust gas can flow, and exhaust particles contained in the exhaust gas can be collected between the meshes.

In FIG. 2, a plurality of electric heater elements 32 are disposed in a distributed manner on the upstream end surface of the trap material 31. As shown in FIG.

Reference numeral 33 is a power terminal of the electric heater element.

Each electrical heating element 32 is preferably a suitable electrical heating element, such as tungsten wrapped in aluminum foil and coated with ceramic.

The size and arrangement of such ceramic heater elements 32 are selected so as not to impede exhaust gas flow and thus minimize exhaust gas backpressure build-up.

The plurality of ceramic heater elements 32 are each sequentially energized and heated.

In the present invention, as shown in Figs. 2 and 3, the collection material (
A catalyst is supported on the trap material 31 in its outer peripheral region in the direction of flow of exhaust gas (indicated by arrow P).

That is, the collection material 31 is made of alumina-coated steel wool (
In the case of a steel foam filter), reference numeral 31a in FIG. 3 is an alumina coat layer that does not support a catalyst, and 31b is a catalyst support layer.

The above-described throttling means, fuel injection timing control means, and heating means using a ceramic heater are operated in conjunction with each other.

For this purpose, engine operating conditions, exhaust gas conditions, etc. are detected and input to the CPU 14.

That is, in FIG. 1, 40 is the engine load, 41 is the engine water temperature, 42 is the engine speed, 43 is the exhaust pressure before the trapper, 44 is the exhaust gas temperature before the trapper, 45 is the temperature inside the trapper, and 46 is the ceramic. This is the heater heating order, and each is input to the CPU 14.

Note that 46 is a heater heating order control, 47 is a power source for heating the ceramic heater, and 48 is a signal wiring for heating the heater.

The trapper container is regenerated as follows.

First, as a condition, the engine water temperature is 41. engine load 4
0, engine speed 42, exhaust gas pressure 43, exhaust gas temperature 44 before the trapper, etc. are input to the CPU 14 (FIG. 1) as information.

The regeneration time is determined mainly based on the back pressure 43 of the exhaust gas.

That is, the exhaust gas discharged from the diesel engine flows as shown by arrow P (Fig. 2), and the particulates contained therein are collected by the trapper material 31, and as the particulates are accumulated, the exhaust gas flows upstream of the trapper container 30. As the pressure increases, this pressure is an indicator of particulate accumulation.

When it is determined that it is the regeneration time, the engine water temperature 41 is checked.

This is to prevent regeneration from starting immediately after the engine is started.

When the engine ice temperature is 110°>T>80°C, the solenoid valve of the fuel injection pump 5 (FIG. 1) is operated to delay the fuel injection timing.

Start throttling again. Throttling ends after a predetermined time.

When the electric heater element is energized for a predetermined period of time, the heating order is counted up.

The injection timing is returned to normal and the glow is turned off to be reset.

If it is determined that regeneration is still necessary after being reset, energization of the next ceramic heater element that was previously energized is started.

After that, the same process is repeated until energization is no longer required for reproduction.

The engine rotational speed 42 at which regeneration is started is not particularly limited, but it is desirable to include a condition such that regeneration is started at idle rotation.

The electric heater element 32 is disposed on the upstream end face of the trap material 31, so when it is heated by electricity, it burns the exhaust particulates adhering to the vicinity and moves the exhaust gas along the flow of the exhaust gas shown by the arrow P. The combustion flame is propagated downstream.

In the present invention, as described above, the outer peripheral area 31 of the trap material 31
b carries a catalyst, so even if the outer circumference of the trap material 31 is cooled by the external atmosphere of the trapper container 30, the action of the catalyst lowers the ignition/combustion temperature of the exhaust particulates, promoting combustion and preventing combustion. There will be no remainder.

The center of the trap material 31, that is, the alumina coat layer 31a
Although no catalyst is supported on the trapper container 30, since the trapper container 30 is not cooled by the atmosphere outside the trapper container 30, ignition and combustion are carried out satisfactorily.

In addition, the catalyst is supported on a collection material (trap material).
31, the discharge of sulfate by the catalyst can be minimized.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a diesel engine using the present invention.
FIG. 2 is a sectional view of the trapper container, and FIG. 3 is a perspective view of the trapping material (trap material) used in the present invention. 1... Diesel engine body, 6...
- Throttle valve, 31... Collection material (trap material), 32... Electric heater element, 31a...
...Layer not supporting catalyst, 31b...
Catalyst support layer.

Claims (1)

[Scope of utility model registration request] A collecting material for exhaust particulates is provided in the exhaust gas passage of a diesel engine, and a means for burning and incinerating the exhaust particulates accumulated in the collecting material is provided, and the collecting material has an outer periphery in the direction of flow of the exhaust gas. 1. An exhaust particulate purification device for a diesel engine, characterized in that the device supports a catalyst in the range.