JPH037007B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a filter regeneration device for an internal combustion engine that removes particulates from exhaust gas discharged from the engine.

Various devices of this type have been studied in the past, one of which is shown in FIG. In FIG. 1, 1 is a diesel engine, 2 is an exhaust manifold attached to the diesel engine 1, and 3 is an exhaust pipe connected to the exhaust manifold 2. In FIG. Reference numeral 4 denotes a filter housing provided in the middle of the exhaust pipe 3, and constitutes a part of the exhaust pipe 3. 5 is a filter stored in the filter storage 4; 9 is the exhaust manifold 2 and the filter storage 4;
10 is a fuel pump that supplies fuel to the filter regeneration burner 9, and 11 is an air pump that supplies combustion air to the filter regeneration burner 9.

Next, the operation of the above device will be explained. Particulate matter in the exhaust gas discharged by the diesel engine 1 passes through the exhaust manifold 2 and the exhaust pipe 3, is filtered by the filter 5 housed in the filter housing 4, and is accumulated in the filter 5. . When particulate accumulates in the filter 5 to a certain extent, the pressure within the exhaust manifold 2 increases, resulting in poor fuel efficiency of the diesel engine 1, and in such a case, the filter 5 must be regenerated. Generally, the main component of particulate is carbon, and its ignition temperature is 500℃.
Before and after. Therefore, it is possible to regenerate the filter 5 by raising the temperature of the filter 5 in which particulates have accumulated to 500° C. or higher. Therefore, the burner 9 burns the fuel and mixes the combustion exhaust gas with the engine exhaust gas to lower the temperature of the engine exhaust gas.
By raising the temperature to 500° C. or higher, the temperature of the filter 5 is indirectly increased and the filter 5 is regenerated. That is, fuel supplied by the fuel pump 10 and combustion air supplied by the air pump 11 are mixed and combusted in the burner 9 to produce high-temperature combustion exhaust gas, which is then converted into engine exhaust gas in the exhaust pipe 3. The feed filter 5 is regenerated.

However, the above device had the following drawbacks. High pressure that can overcome exhaust pressure (usually
0.8Kg/cm2 or ^more ) and large flow rate (usually 100/min)
The air pump 11 and fuel pump 10 (as described above) are required, making the device large and expensive. Since exhaust pressure fluctuates depending on engine operating conditions, it is necessary to control air pressure and fuel pressure accordingly, which is troublesome. Fluctuations in exhaust pressure cause combustion in the burner 9 to become unstable, making it difficult to regenerate the filter 5.

The present invention was made in order to eliminate the above-mentioned conventional drawbacks, and the exhaust pipe of an internal combustion engine is branched into two, an exhaust gas switching valve is provided at the branch point, and a microwave is connected to one of the exhaust gas passages. A reflector, a particulate filter, and a case for storing the same are provided, and the other exhaust gas passage bypasses the particulate filter and merges with the one exhaust gas passage in front of the muffler,
The case is provided with a microwave supply path and an air supply path, and by simultaneously supplying microwaves and air, the particulates adhering to the filter are selectively heated and burned, and the filter is removed regardless of the operating state of the engine. An object of the present invention is to provide a filter regeneration device for an internal combustion engine that regenerates stably and efficiently.

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 2, 3a and 3b are exhaust branch pipes formed by branching the exhaust pipe 3 up to just before the muffler 13;
A filter housing 4 housing a filter 5 is disposed in the middle of one exhaust branch pipe 3a. Reference numeral 7 denotes a microwave supply path branched to the filter housing 4 which is a part of the exhaust branch pipe 3a; 8 is a microwave oscillator formed by, for example, a magnetron; the oscillator 8 is connected to the microwave supply path 7; will be installed on the 12 is a microwave power source that drives the microwave oscillator 8; 15 is an exhaust gas switching valve provided at a branch point of the exhaust pipe 3; and 17 is an air supply for supplying air from the air pump 16 to the filter housing 4. A channel 6 is a microwave reflecting plate for confining microwaves in the filter housing 4, and the reflecting plates 6 are provided on the upstream and downstream sides of the filter housing 4 and on the air supply path 17, respectively. 18 is an air switching valve.

Next, the operation of the above device will be explained. When it becomes necessary to regenerate the filter 5, the exhaust gas switching valve 15 closes the exhaust branch pipe 3a, and the exhaust gas from the engine 1 bypasses the filter housing 4 and enters the muffler 13 via the exhaust branch pipe 3b. Let it flow. Also, open the air switching valve 18. Next, the air pump 16 and the microwave power source 12 are energized, and the air is supplied to the air supply path 17 and the microwave reflector 6.
The microwave power is supplied from the microwave oscillator 8 to the filter housing 4 through the microwave supply path 7 . The microwave reflecting plate 6 is made of, for example, a metal mesh or a cross-shaped metal plate, and reflects microwave power, but allows fluids such as air and exhaust gas to pass through without pressure loss. Therefore, the supplied microwave power exists only within the filter housing 4, but the air supplied from the air pump 16 passes through the filter 5 and is discharged to the outside from the muffler 13. Due to the nature of microwaves, the microwave power in the filter housing 4 is absorbed only by the particulates deposited on the filter 5, and the particulates are selectively heated. In this way, the particulate is heated above its ignition point and oxidized. At this time, the necessary air is supplied from the air pump 16. As a result, the particulate deposited on the filter 5 is burned, and the filter 5 is regenerated.

When the regeneration is completed, the exhaust gas switching valve 15 is switched, the exhaust branch pipe 3a is opened, the exhaust branch pipe 3b is closed, and the air switching valve 1 is switched.
8 is closed. Therefore, exhaust gas from the engine 1 passes only through the filter 5 in the filter housing 4 and is discharged from the muffler 13. This state continues until the next regeneration is performed, and particulates in the exhaust gas are deposited on the filter 5.

In the above embodiment, the air switching valve 18 is provided in the filter housing 4, but the ON-
Similar effects can be obtained by providing the OFF solenoid valve at any position in the air supply path 17. Further, as the microwave supply path 7, a tube, a freely bendable coaxial cable, or the like can be used.

As described above, in the present invention, when the filter is regenerated, exhaust gas from the internal combustion engine is not allowed to flow through the filter, and microwave power and air are supplied to the filter to selectively heat the particulates deposited on the filter. This allows the particulate to be burned off and the filter to be regenerated. Therefore, there is no need for a fuel pump, and since there is no need for an air pump as an air source to counter exhaust pressure, a low-pressure, small-flow type is sufficient.
The device is small and inexpensive. Furthermore, since it is not affected by exhaust pressure, the filter can be regenerated stably and efficiently regardless of the operating point of the engine.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a conventional filter regeneration device, and FIG. 2 is a configuration diagram of a filter regeneration device according to the present invention. 1... Diesel engine, 2... Exhaust manifold, 3... Exhaust pipe, 4... Filter storage container,
5...Filter, 6...Microwave reflector, 7...
...Microwave supply path, 8...Microwave oscillator,
13...muffler, 15...exhaust gas switching valve,
16...Air pump, 17...Air supply path, 18
...Air switching valve. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. Each exhaust branch pipe formed by branching an exhaust pipe of an internal combustion engine into two; a filter provided on one exhaust branch pipe to remove particulates from exhaust gas; a microwave oscillator installed in the exhaust branch pipe and generating microwaves for the filter;
An air source connected to the upstream side of the filter in one exhaust branch pipe via an air supply path, and an air source connected to the upstream and downstream sides of the filter in one exhaust branch pipe and the air supply path to reflect microwaves. and each microwave reflection plate through which fluid flows, an exhaust gas switching valve that is installed at the branch point of the exhaust pipe and closes one exhaust branch pipe when the filter is regenerated and opens the other exhaust branch pipe when the filter is regenerated. A filter regeneration device for an internal combustion engine, comprising an air switching valve that opens an air supply path. 2. The filter regeneration device for an internal combustion engine according to claim 1, wherein the microwave reflecting plate is constructed of a metal mesh or a cross-shaped metal plate.