JP2717892B2 - Exhaust gas purification device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a SO containing in particulates discharged from a diesel vehicle using a catalyst.
The present invention relates to an exhaust gas purification device that reduces F.

[0002]

2. Description of the Related Art Since particulates emitted from diesel vehicles contain SOF, an exhaust gas device for removing the particulates using an oxidation catalyst has been conventionally developed. In this exhaust gas purifying apparatus, the SOF is adsorbed on the oxidation catalyst when the exhaust gas temperature is in the range of 20 to 200 ° C. When the exhaust gas temperature is raised to 200 ° C. or higher, when the temperature rises, There was a problem that the adsorbed SOF was desorbed from the oxidation catalyst and released into the atmosphere.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to reduce the SOF contained in particulates and discharged from a diesel engine with exhaust gas. Particularly, even when the temperature of the exhaust gas is increased, the SOF is reduced. It is an object of the present invention to provide an exhaust gas purifying apparatus that prevents emission of methane into the atmosphere.

[0004]

Means corresponding to the object and the operation thereof
A main oxidation device having an oxidation catalyst and disposed in the middle of an exhaust pipe of a diesel engine, a filter and an oxidation catalyst sequentially arranged in series from upstream to downstream with respect to the flow of exhaust gas of the engine, On the downstream side of the main oxidizer, an auxiliary oxidizer connected to the exhaust pipe by a branch pipe, and on the downstream side of the point where the branch pipe is connected, a main shutoff valve arranged on the exhaust pipe, An auxiliary shut-off valve located in the pipe, its engine speed and load,
And a computer that controls the opening and closing of the main and auxiliary shut-off valves according to the temperature of the exhaust gas at the inlet side and the outlet side of the main oxidizer, and when the exhaust gas is at a low temperature, The SOF contained in the discharged particulates is adsorbed on the oxidation catalyst of the main oxidizer, and the SOF desorbed from the oxidation catalyst when the temperature of the exhaust gas is increased is accompanied by the particulates. And collect it in the filter of the auxiliary oxidizer,
Then, the filter is regenerated while burning the collected particulates with high-temperature exhaust gas, and the hydrocarbons generated at that time are oxidized by the oxidation catalyst of the auxiliary oxidation device.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific embodiment of the exhaust gas system of the present invention will be described below with reference to the drawings. 1 and 2 show a specific example 10 of the exhaust gas purifying apparatus of the present invention applied to a diesel vehicle. The exhaust gas purifying device 10 is applied to an exhaust system of a diesel engine 40 mounted on the diesel vehicle, and includes a main oxidizing device 1.
1, auxiliary oxidizer 12, main shut-off valve 13, auxiliary shut-off valve 1
4. Opening and closing the main and auxiliary shut-off valves 13 and 14 according to the rotation speed and load of the engine 40 and the temperature of the exhaust gas of the diesel engine 40 at the inlet and outlet of the main oxidizer 11 Assembled by the controlling computer 15.

The main oxidizer 11 comprises a casing 18 having a flanged inlet and an outlet, and an oxidation catalyst 19 incorporated in the casing 18. An inlet and an outlet are flanged and disposed in the exhaust pipe 42. When the exhaust gas of the diesel engine 40 is at a low temperature, the SOF contained in the particulates discharged along with the exhaust gas is converted into the oxidation catalyst 19 Absorbable on top. The oxidation catalyst 19 also includes a carrier molded in a mold from ceramic powder and manufactured through a drying and firing step into a honeycomb structure consisting of a number of cells open at both ends, and supported on the carrier. Have been.

As shown in FIG. 2, the auxiliary oxidizer 12 includes a casing 20 having a flanged inlet 21 and an outlet 22, and a predetermined flow from the upstream side to the downstream side with respect to the flow of exhaust gas from the engine 40. A particulate filter 23 and an oxidation catalyst 24 which are sequentially arranged in series at intervals and are incorporated in the casing 20 thereof.
The inlet 21 is connected to the exhaust pipe 42 at the branch pipe 16 on the downstream side of the main oxidizer 11, and the exhaust pipe 4 is connected on the downstream side of the main shutoff valve 13.
When the temperature of the exhaust gas rises from low to high, the outlet 22 is connected to the main oxidizer 1 by a return pipe 17.
The SOF desorbed from the oxidation catalyst 1 is collected by the particulate filter 23 along with the particulates, and the particulate filter is burned with high-temperature exhaust gas while burning the collected particulates. 23 was regenerated, and the hydrocarbon (HC gas) generated at that time was made oxidizable by the oxidation catalyst 24.

[0008] The particulate filter 23
It is molded in a mold from ceramic powder, and is made into a gas-permeable honeycomb structure composed of a large number of cells each of which is closed in a staggered pattern at both ends through a drying and firing process. It includes a carrier molded in a mold from ceramic powder and manufactured through a drying and firing process into a honeycomb structure consisting of a large number of cells open at both ends, and supported by the carrier.

The main shutoff valve 13 is provided with a butterfly valve 25 disposed on the exhaust pipe 42 and a butterfly valve 2 on the downstream side of the location where the branch pipe 16 is connected.
5 was assembled from an electric motor 26 for opening / closing operation.

The auxiliary shut-off valve 14 is assembled from a butterfly valve 27 disposed in the branch pipe 16 and an electric motor 28 for opening and closing the butterfly valve 27.

The computer 15 has its main and auxiliary shutoffs depending on the speed and load of the diesel engine 40 and the temperature of the exhaust gas of the diesel engine 40 at the inlet and outlet sides of the main oxidizer 11. The valves 13 and 14 are controlled to open and close, and the main oxidizer 1
1 removes SOF contained in the exhaust gas, and the auxiliary oxidizer 12 oxidizes SOF desorbed from the oxidation catalyst 19 of the main oxidizer 11.

More specifically, the computer 15 includes an engine rotation sensor 29, an engine load sensor 30, and exhaust gas temperature sensors 31 and 3 as input circuits.
2 are electrically connected, while the output circuits are electrically connected to the electric motors 26, 28 of the main and auxiliary shut-off valves 13, 14, and are connected to each other based on a control pattern previously input to a memory. Open / close control. Of course, the control pattern is that if the exhaust gas has a low temperature of 20 to 200 ° C.,
Its main shut-off valve 13 opens and at the same time its auxiliary shut-off valve 14
Is closed to allow the main oxidizer 11 to adsorb the SOF, and when the exhaust gas is raised to 200 ° C. or higher, the main shutoff valve 13
Is closed and its auxiliary shut-off valve 14 is opened to open its main oxidizer 1
When the SOF desorbed from the first oxidation catalyst 19 is collected by the auxiliary oxidation device 12, the main shut-off valve 13 is opened again after a certain period of time, and at the same time,
The auxiliary shutoff valve 14 is closed and the SO contained in the exhaust gas is closed.
Is further oxidized by the main oxidizer 11, and when the exhaust gas temperature exceeds 500 ° C., the auxiliary shutoff valve 14 is also opened to a certain degree, and the high-temperature exhaust gas is transmitted to the auxiliary oxidizer 12. The particulates and SOF collected in the particulate filter 23 are burned with the high-temperature exhaust gas to regenerate the particulate filter 23, and the hydrocarbons generated at that time are transferred to the oxidation catalyst 24. It is summarized in the place where it is oxidized.

The rotation sensor 29 is connected to the diesel engine.
On the crankshaft of the engine 40, its load sensor 30 is arranged on the fuel injection pump 41 of its diesel engine 40, respectively, while its temperature sensor 3
1 and 32 are disposed in the exhaust pipe 42 on the upstream and downstream sides of the main oxidizer 11.

Next, the exhaust gas purifying apparatus 10 described above is used.
Will be described in relation to the operation state of the diesel engine 40. Now, when the diesel vehicle is stopped and the diesel engine 40 is operating in an idling state, the exhaust gas of the diesel engine 40 is at a low temperature. , And a temperature sensor 31,
32, the signals are electrically input, and the signals are compared with the control pattern. The output currents of the main and auxiliary shutoff valves 13, 14 are read from the control pattern, and the read output currents are used to control those motors. The motors 26 and 28 are controlled. In this case, since the butterfly valve 25 is opened by the electric motor 26 and at the same time the butterfly valve 27 is closed by the electric motor 28, the exhaust gas of the diesel engine 40 is exhausted by the exhaust manifold (not shown), It flows upstream of the exhaust pipe 42, flows into the casing 18 of the main oxidizer 11, and passes through the oxidation catalyst 19. At that time, SOF contained in the particulates discharged along with the exhaust gas is adsorbed on the oxidation catalyst 19. The exhaust gas from which the SOF has been removed by the main oxidizer 11 flows from the casing 18 to the downstream side of the exhaust pipe 42, and is discharged to the atmosphere.

In such a state, when the diesel vehicle is started, the diesel engine 40 is operated under load, so that the temperature of the exhaust gas of the diesel engine 40 is increased from a low temperature to a high temperature. Then, the computer 15 inputs the fact that the temperature of the exhaust gas has risen as an electric signal from the rotation sensor 29, the load sensor 30, and the temperature sensors 31 and 32, and compares the signal with the control pattern. The output currents of the main and auxiliary shutoff valves 13 and 14 are read from the control pattern, and the electric motors 26 and 2 are read with the read output currents.
7 is controlled.

In the transitional period in which the temperature rises as described above, the SOF adsorbed on the oxidation catalyst 19 of the main oxidation device 11 along with the particulates is desorbed from the oxidation catalyst 19. During a certain time, in the main shut-off valve 13, the butterfly valve 25 is closed by the electric motor 26, while in the auxiliary shut-off valve 14, the butterfly valve 27 is closed by the electric motor 28.
The exhaust gas of the diesel engine 40 flows from the main oxidizer 11 to the auxiliary oxidizer 12 through the branch pipe 16, further flows downstream of the return pipe 17 and the exhaust pipe 42, and Will be released. Since the exhaust gas thus flows, the SOF desorbed from the oxidation catalyst 19 in the main oxidizer 11 is collected in the particulate filter 23 in the auxiliary oxidizer 12, and the exhaust gas is purified. Is released into the atmosphere in a state where it is left out.

After the predetermined time has elapsed, the computer 15 controls the electric motors 26 and 28 so that the butterfly valve 25 is opened by the electric motor 26 at the main shut-off valve 13 and at the same time, In the auxiliary shut-off valve 14, the butterfly valve 27 is closed by the electric motor 28, and after the exhaust gas has passed through the main oxidizer 11, the exhaust gas flows downstream of the exhaust pipe 42 and is discharged to the atmosphere. Is done. In this case, the diesel engine 4
SOF discharged from the main oxidation unit 11 is subjected to an oxidation treatment.

Further, when the temperature of the exhaust gas increases as the diesel vehicle travels, the computer 15
Indicates that the temperature of the exhaust gas has become high.
An electric signal is input from the control signals 1 and 32, the signal is compared with the control pattern, the output current of the auxiliary cutoff valve 14 is read from the control pattern, and the electric motor 28 is controlled by the read output current. . In the auxiliary shutoff valve 14, the butterfly valve 27 is opened to a predetermined opening by the electric motor 28, and a part of the exhaust gas passing through the main oxidizer 11 passes through the branch pipe 16 to the auxiliary It flows to the oxidizer 12. In the auxiliary oxidizer 12, the SOF collected by the particulate filter 23 along with the particulate is burned by the high-temperature exhaust gas, and as a result, the particulate filter 23 is regenerated. . Further, hydrocarbons (HC gas) generated during the combustion are oxidized on the oxidation catalyst 24, flow to the downstream side of the return pipe 17 and the exhaust pipe 42 along with the exhaust gas, and enter the atmosphere. Released.

When a predetermined time has elapsed or when the temperature of the exhaust gas has dropped, the computer 15 closes the auxiliary shut-off valve 14 and again in the main oxidizer 11 with the particulates. In this state, SOF contained in the exhaust gas is adsorbed.

FIGS. 3 and 4 show another embodiment 50 of the exhaust gas purifying apparatus of the present invention applied to a diesel vehicle. This exhaust gas purification device is applied to the exhaust system of the diesel engine mounted on the diesel vehicle,
Main oxidizer 11, filter device 51, heat exchange type auxiliary oxidizer 52, main shut-off valve 13, auxiliary shut-off valve 14, its engine speed and load, and the inlet and outlet sides of main oxidizer 11 Its diesel in
It was assembled by a computer 15 that controls opening and closing of the main and auxiliary shutoff valves 13 and 14 according to the temperature of the exhaust gas of the engine.

The filter device 51 includes a casing 54 having a flanged inlet and outlet, and a particulate filter 23 incorporated in the casing 54.
And was connected to the exhaust pipe 42 by a branch pipe 16 on the downstream side of the main oxidizer 11.

The heat-exchange auxiliary oxidizer 52 is manufactured by incorporating a large number of oxidation catalysts 63 into a plate-type heat exchanger using a large number of thin flat plates 60 for partition walls, as shown in FIG. , Casing 55 and its casing 5
5, a plurality of flat plates 60 forming a plurality of high-temperature gas passages 61 and low-temperature gas passages 62 which are separated from each other in a casing 55 and exchange heat, and the low-temperature gas It was assembled with a number of oxidation catalysts 63 arranged in a passage 62.

Further, the heat exchange type auxiliary oxidation device 52
The flanged hot gas inlet 56 and outlet 57 connected to the hot gas passage 61 and the flanged cold gas inlet 58 and outlet 59 connected to the cold gas passage 62 are formed in the casing 55 at predetermined positions. Then, on the upstream side of the main oxidizer 11, the hot gas inlet 56 and the outlet 57 are flange-coupled in the middle of the exhaust pipe 42 to connect the hot gas passage 61 to the exhaust pipe 42, The low temperature gas inlet 58 is connected to the outlet of the filter device 51 by the connecting pipe 53 which is flanged to each other, the low temperature gas passage 62 is connected to the outlet side of the filter device 51, and the return flanges are connected to each other. The low temperature gas outlet 59 is connected to the downstream side of the exhaust pipe 42 by the pipe 17 and the exhaust pipe 4
The low temperature gas passage 62 was connected to the downstream side of No. 2 and used. Of course, the return pipe 17 was connected to the exhaust pipe 42 on the downstream side of the main shutoff valve 13.

In the heat exchange type auxiliary oxidizer 52 manufactured and connected to such a structure, the exhaust gas flowing through the low-temperature gas passage 62 located downstream of the exhaust pipe 42 is supplied to the exhaust pipe. Heated by the exhaust gas flowing in the high-temperature gas passage 61 located upstream of 42, the oxidation catalyst 63 arranged in the low-temperature gas passage 62 is activated so as to sufficiently exert a catalytic action. By the way. That is, the heat exchange type auxiliary oxidation device 5
In 2, when the temperature of the exhaust gas is increased from a low temperature to a high temperature, the exhaust gas is desorbed from the oxidation catalyst 19 of the main oxidizer 11,
The SOF collected by the particulate filter 23 of the filter device 51 accompanying the particulate is
In the filter device 51, hydrocarbons (HC gas) are generated by burning with high-temperature exhaust gas, and the generated hydrocarbons are oxidized by the oxidation catalyst 6 at a high conversion rate.
3 can be oxidized.

The exhaust gas purifying device 50 operates similarly to the exhaust gas purifying device 10 described above to purify the exhaust gas of the diesel engine 40. In the exhaust gas purifying apparatus 50, since the auxiliary oxidizing apparatus 52 is configured as a heat exchanger, the SOF collected in the particulate filter 23 accompanying the particulates in the filter apparatus 51 is included. Was burned with high-temperature exhaust gas, and hydrocarbons generated when the particulate filter 23 was regenerated were oxidized at a higher conversion ratio than that of the exhaust gas purifier.

[0026]

As will be understood from the above description, the exhaust gas purifying apparatus of the present invention includes a main oxidizing apparatus having an oxidation catalyst and disposed in the exhaust pipe of a diesel engine, and a flow of exhaust gas from the engine. A filter and an oxidation catalyst are sequentially arranged in series from the upstream side to the downstream side, and the auxiliary oxidation unit connected to the exhaust pipe by a branch pipe on the downstream side of the main oxidation unit is connected to the branch pipe. A main shut-off valve arranged in the exhaust pipe on the downstream side of the
Auxiliary shut-off valves arranged in the branch pipes, and control of opening and closing of the main and auxiliary shut-off valves according to the rotation speed and load of the engine and the temperature of the exhaust gas at the inlet and outlet sides of the main oxidizer. Since the exhaust gas purification apparatus of the present invention includes a computer,
When the exhaust gas of the engine is at a low temperature, the SOF contained in the particulates and discharged from the diesel engine along with the exhaust gas can be adsorbed on the catalyst. During the transition to elevated temperatures, the SOF desorbed from the catalyst is collected and allowed to be oxidized while burning the particulates with hot exhaust gases, and is thus discharged from the diesel engine. SOF is reduced so that its exhaust gas can be purified, and is very useful and practical for diesel vehicles.

Further, the exhaust gas purifying apparatus of the present invention comprises a main oxidizing device having an oxidation catalyst and arranged in the exhaust pipe of a diesel engine, and a filter having a filter on the downstream side of the main oxidizing device. A filter device connected to the exhaust pipe by a branch pipe, and a high-temperature gas path and a low-temperature gas path that are separated from each other by a partition and exchange heat, and
An oxidation catalyst is arranged in the low-temperature gas passage, and the high-temperature gas passage is connected to the exhaust pipe on the upstream side of the main oxidizer, and the low-temperature gas passage is arranged on the exhaust pipe. A heat exchange type auxiliary catalyst device for connecting the gas passage, a main shut-off valve disposed on the exhaust pipe, and an auxiliary shut-off valve disposed on the branch pipe, at a downstream side of a location connecting the branch pipe; The exhaust gas purifying apparatus according to the present invention includes a computer that controls opening and closing of the main and auxiliary shut-off valves according to the engine speed and load, and the temperature of the exhaust gas at the inlet side and the outlet side of the main oxidizer. When the exhaust gas of the diesel engine is at a low temperature, the SOF contained in the particulates and discharged from the diesel engine along with the exhaust gas On the catalyst enables adsorption treatment, in particular, in transition temperature of the exhaust gas is increased from a low temperature to a high temperature, its SOF are collected desorbed from the catalyst,
The SOF discharged from the diesel engine can be oxidized while being heated to a high temperature while burning the particulates with the high-temperature exhaust gas.
Is further reduced to improve the purification of the exhaust gas, and is more useful and practical for diesel vehicles.

As apparent from the embodiments of the present invention described above with reference to the drawings, the contents of the present invention will be explained to those skilled in the art to which the present invention belongs. It is derived from the technical essence of the invention, which is essential for the achievement of the invention and is the nature of the invention in order to achieve the object of the invention, and is easily realized in an aspect which is objectively recognized as being inherent. Embodied in

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a specific example of an exhaust gas purifying apparatus of the present invention applied to a diesel engine in a diesel vehicle.

FIG. 2 is a cutaway perspective view of an auxiliary oxidation device of the exhaust gas purification device shown in FIG.

FIG. 3 is a schematic diagram showing another specific example of the exhaust gas purifying apparatus of the present invention applied to a diesel engine in a diesel vehicle.

FIG. 4 is a perspective view of the heat exchange type auxiliary oxidation device of the exhaust gas purification device shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Main oxidizing device 12 Auxiliary oxidizing device 13 Main shutoff valve 14 Auxiliary shutoff valve 16 Branch pipe 17 Return pipe 19 Oxidation catalyst 23 Particulate filter 24 Oxidation catalyst 51 Filter device 52 Heat exchange type auxiliary oxidization device 53 Communication tube

Claims (2)

(57) [Claims] 1. A main oxidizer having an oxidation catalyst and disposed in the exhaust pipe of a diesel engine, a filter and an oxidizer sequentially arranged in series from upstream to downstream with respect to the flow of exhaust gas from the engine. An auxiliary oxidizer having a catalyst and connected to the exhaust pipe by a branch pipe on the downstream side of the main oxidizer, and a main shutoff disposed on the exhaust pipe downstream of a point where the branch pipe is connected A valve, an auxiliary shut-off valve arranged in the branch pipe, and the main and auxiliary shut-off valves according to the rotation speed and load of the engine, and the temperature of the exhaust gas on the inlet side and the outlet side of the main oxidizer. An exhaust gas purifying apparatus including a computer that controls opening and closing. 2. A main oxidizer having an oxidation catalyst and disposed in the exhaust pipe of a diesel engine, and a filter having a filter and connected to the exhaust pipe downstream of the main oxidizer by a branch pipe. A high-temperature gas passage and a low-temperature gas passage, which are separated from each other by a partition to exchange heat, and an oxidation catalyst is arranged in the low-temperature gas passage, and the upstream side of the main oxidization device is provided with an oxidation catalyst. A heat exchange type auxiliary oxidizer that connects the high-temperature gas passage to the exhaust pipe and is arranged in the exhaust pipe, and connects the low-temperature gas passage to the outlet side of the filter device, and a portion connecting the branch pipe. On the downstream side, a main shut-off valve arranged in the exhaust pipe, an auxiliary shut-off valve arranged in the branch pipe, the engine speed and load, and the inlet and outlet sides of the main oxidizer And a computer that controls the opening and closing of the main and auxiliary shut-off valves according to the temperature of the exhaust gas in (1).