JPH037006B2 - - 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.

Conventionally, various devices of this type have been studied, one of which is shown in FIG. 1. In FIG. 1, 1 is a diesel engine, 2 is an exhaust manifold attached to the diesel engine 1, 3 is an exhaust pipe connected to the exhaust manifold 2, and 4 is a filter storage device provided in the middle of the exhaust pipe 3. This constitutes a part of the exhaust pipe 3. 5 is a filter stored in the filter storage container 4; 9 is the exhaust manifold 2 and the filter storage container 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.

The operation of the above conventional device will be explained. Particulate matter in the exhaust gas discharged by the diesel engine 1 passes through an exhaust manifold 2 and an exhaust pipe 3, and passes through a filter 5 housed in a filter housing 4.
is filtered and accumulated in this filter 5. When particulate accumulates in the filter 5 to a certain extent, the pressure within the exhaust manifold 2 increases and the fuel efficiency of the diesel engine 1 deteriorates, so the filter 5 must be regenerated at this time. Generally, the main component of particulate is carbon, and its ignition temperature is around 500°C.
Therefore, if the temperature of the filter 5 in which particulates have been accumulated is raised to 500° C. or higher by some method, the particulates will be burned off and the filter 5 can be regenerated. In the case of Fig. 1, the temperature of the filter 5 is indirectly increased by burning fuel in the burner 9, mixing the combustion exhaust gas with engine exhaust gas, and raising the temperature of the engine exhaust gas to 500°C or higher. , 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. This means that the feed filter 5 is regenerated.

However, the above device had the following drawbacks. (1) High pressure that can overcome exhaust pressure (usually
0.8Kg/cm2 or ^more ) and large flow rate (usually 100/min)
Since the air pump 11 and fuel pump 10 (as described above) are required, the device is large and requires a large amount of electric power, making it expensive. (2) Since exhaust pressure fluctuates depending on engine operating conditions, it is necessary to control air pressure and fuel pressure, which is troublesome. (3) Combustion within the burner 9 became unstable due to fluctuations in exhaust pressure, making it difficult to regenerate the filter 5 stably.

This 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, and one exhaust gas passage is equipped with a microwave reflector, a particulate filter, and a particulate filter. A storage case is provided therein, an appropriate pressure loss body and an ON-OFF solenoid valve are provided in the other exhaust gas passage, and the other exhaust gas passage is connected to the one exhaust gas passage in a manner that bypasses the particulate filter. The particulates adhering to the particulate filter are selectively heated and burned by merging them in front of the muffler, and by providing a microwave supply path in the storage case and supplying microwaves from a microwave oscillator, the particulates adhering to the particulate filter are selectively heated and burned. An object of the present invention is to provide a filter regeneration device for an internal combustion engine that is less affected by the operating state of the engine and can regenerate the filter 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 which branched the exhaust pipe 3 into two.
A filter storage container 4 containing a filter 5 is disposed at a. Reference numeral 7 denotes a microwave supply path consisting of a waveguide branched into the filter housing 4 which is a part of the exhaust branch pipe 3a, and 8 is a microwave oscillator attached to the microwave supply path 7, such as a magnetron or the like. It consists of 12 is a microwave oscillator 8
6 is a microwave reflector provided in the exhaust branch pipe 3a on the outlet and inlet sides thereof to confine microwaves in the filter housing 4; 15 is a microwave reflector provided in the exhaust branch pipe 3b; 14 is a pressure loss body that provides an appropriate pressure drop to the exhaust gas flowing through the exhaust branch pipe 3b; 13 is a muffler installed in the exhaust pipe 3 after the exhaust branch pipes 3a and 3b join together; be.

In the above device, when it becomes necessary to regenerate the filter 5, the solenoid valve 15 is first opened, and most of the exhaust gas emitted from the engine 1 bypasses the filter housing 4 and is exhausted from the exhaust branch pipe 3b through the muffler 13. to be done. At this time, pressure loss body 1
Due to the pressure drop caused by 4, a portion of the exhaust gas flows into the filter housing 4. Next, microwave power is supplied from the microwave oscillator 8 to the filter housing 4 via 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 it without pressure loss. Therefore, the supplied microwave power exists only within the filter housing 4. on the other hand,
Oxygen necessary for oxidizing particulate is supplied from the exhaust gas flowing through the filter housing 4. 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, oxidized and burned,
Filter 5 is regenerated. When the regeneration is completed, the solenoid valve 15 is closed, and the exhaust gas from the engine 1 passes only through the exhaust gas branch pipe 3a 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 and removed from the exhaust gas.

3 and 4 show second and third embodiments of this embodiment, respectively, and in the case of FIG. 3, the microwave power source 12 is driven by the AC output of the alternator 20 attached to the engine 1. In the case of FIG. 4, the AC output obtained by converting the AC output of the alternator 20 or the DC output of the battery 21 via the inverter 22 is applied to the microwave power source 12. In either example, the power source The configuration can be simplified.

In each of the above embodiments, a waveguide is used as the microwave supply path 7, but a freely bendable coaxial cable may also be used. Further, it is not necessary to align the axes of the microwave supply path 7 and the filter 5, and any arrangement is sufficient as long as the filter 5 and the microwave supply path 7 are effectively sandwiched between the two microwave reflection plates 6. . Further, if the engine is a gasoline engine, the same effect as in the above embodiment can be obtained by burning the mixture at a level lower than the stoichiometric mixture ratio when regenerating the filter 5.

As described above, in the present invention, when the filter is regenerated, part of the engine exhaust gas is supplied to the filter, and microwave power is supplied only to the filter, and this microwave power selectively removes only the particulates deposited on the filter. It heats and burns it to remove it, eliminating the need for high-pressure, large-flow air pumps and fuel pumps like in the past.
The device is small and does not require a large amount of electric power, making it inexpensive. In addition, there is no need to control the air pressure and fuel pressure of the pump in response to the exhaust pressure, which changes depending on the engine operating condition. The filter can be regenerated stably and efficiently with almost no influence.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional device, and FIGS. 2 to 4 are block diagrams of first to third embodiments of the device of the present invention, respectively. 1... Diesel engine, 2... Exhaust manifold, 3... Exhaust pipe, 3a, 3b... Exhaust branch pipe, 4... Filter storage, 5... Filter, 6
...Microwave reflector, 7...Microwave supply path, 8...Microwave oscillator, 12...Microwave power supply, 13...Muffler, 14...Pressure loss body, 15
... Solenoid valve, 20 ... Alternator, 21 ...
Battery, 22...Inverter. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. Exhaust pipes of an internal combustion engine are branched and merged up to the muffler, and one exhaust branch pipe is equipped with a filter for removing particulates in the exhaust gas and microwaves driven by a microwave power source. In addition to providing a microwave oscillator that generates microwaves, a microwave reflecting plate that allows exhaust gas to flow and reflects microwaves is installed on the upstream and downstream sides of the filter and microwave oscillator installation position in one exhaust branch pipe, respectively. , and the other exhaust branch pipe is provided with a valve mechanism that opens and closes the pipe and a pressure loss body that allows part of the exhaust gas to flow into the other exhaust branch pipe when the valve mechanism is opened, that is, when the filter is regenerated. A filter regeneration device for an internal combustion engine, characterized in that: 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. 3. An internal combustion engine according to claim 1 or 2, characterized in that when the internal combustion engine is a gasoline engine, the internal combustion engine is operated at an air-fuel ratio thinner than the stoichiometric mixture ratio during filter regeneration. Filter regeneration device. 4. Claims 1 to 3, characterized in that the power of the microwave power source that drives the microwave oscillator is obtained from the AC output of an alternator or the AC output obtained by converting the DC output of a battery into AC using an inverter. 3. The filter regeneration device for an internal combustion engine according to any one of the items.