US20080155966A1

US20080155966A1 - Exhaust Gas Purifier of Engine used in Locomotive

Info

Publication number: US20080155966A1
Application number: US11/672,033
Authority: US
Inventors: Wen Shing Chang
Original assignee: Sentec E&E Co Ltd
Current assignee: Sentec E&E Co Ltd
Priority date: 2006-12-29
Filing date: 2007-02-06
Publication date: 2008-07-03
Also published as: TW200827536A; JP4486981B2; JP2008163933A; TWI319459B

Abstract

A exhaust gas cleaning purifier used in an engine of a locomotive, which is arranged between an exhaust pipe of the engine and a silencer connecting to the exhaust pipe, includes a front supply pipe and a back supply pipe configured for supplying secondary air, at least one front catalyst converter for making an oxidation reaction and at least one middle catalyst converter for making an reduction reaction, and at least one back catalyst converter arranged after the silencer and the back supply pipe. The front supply pipe connects with the exhaust terminal of the engine, and the back supply pipe connects with the silencer. The at least one front catalyst converter and the at least one middle catalyst converter are arranged in the silencer and arranged between the front and back supply pipes. A dissipating-heat distance is defined between the front catalyst converter and the middle catalyst converter.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to an exhaust gas purifier and, more particularly, to an exhaust gas purifier which can effectively purify the gas exhausted from an engine of a locomotive.
2. Description of the Related Art
The locomotive engines, more particularly the two-cycle locomotive engines, are different from the automobile engines since they burn insufficiently to exhaust noxious exhaust gases. Furthermore, the automobile engines have a perfect engine control unit (ECU) to obtain more environmental parameters so as to ensure the normal operation of the engine and decrease the exhaust of the exhaust gases.
Furthermore, not only the two-cycle locomotive engines, but also the four-cycle automobile or locomotive engines, have a catalyst converter arranged on a exhaust gas exhaust pipe. The catalyst converter is a metal cylinder covering a catalyst. The catalyst may include noble metals, such as Pd, Pt, and Rh, etc. The Pd and Pt elements are advantageous to oxidize the noxious carbon monoxide and the hydrogen carbide to the innoxious carbon dioxide and the water. The Rh element can deoxidize the noxious nitrogen oxide (NOx) to the innoxious nitrogen and the oxygen to clean the exhaust gas and decrease the effects of the exhaust gas.
To increase the efficiency of oxidizing the exhaust gas by the catalyst, a conventional art guides the secondary air into the catalyst converter, which is mainly used to oxidizing the exhaust gas, for obtaining the enough oxygen and oxidizing the carbon monoxide and the hydrogen carbide to the carbon dioxide and the water. The conventional art is disclosed in a JP Patent No. 2004-36440. The patent discloses an exhaust gas purifier used in an engine, which has a chamber arranged on the engine exhaust pipe before a silencer to contain the two catalyst converters. The secondary air is guided therein at an appropriate time to make the catalyst in the front catalyst converter make a reduction reaction with the exhaust gas, and make the catalyst in the back catalyst converter make an oxidation reaction with the exhaust gas for cleaning the exhaust gas and eliminating the noxious matters. However, if stop guiding the secondary air, the front and back catalyst converters only make the reduction reaction with the exhaust gas, and the oxidation reaction with the exhaust gas weakens such that it is not advantageous for cleaning the exhaust gas by oxidizing and deoxidizing the exhaust gas synchronously.
Furthermore, a TW patent No. 1234604 discloses an engine, which is same to that of the above conventional art, except that the engine further includes a front secondary air supply pipe arranged in the exhaust pipe before the front catalyst converter. The front secondary air supply pipe cooperates with the back secondary sir supply pipe arranged between the front and back catalyst converters described in the above, to synchronously supply the enough oxygen into the front and back catalyst converters or only supply the enough oxygen into the back catalyst converters such that the exhaust gas is not only oxidized in the time of opening the front secondary air supply pipe and but also is deoxidized in the time of stopping the front secondary air supply pipe. However, if the front and back secondary air supply pipes are open synchronously, the secondary air make the reaction with the catalysts in the front and back catalyst converters synchronously such that the noxious nitrogen oxide of the exhaust gas can not be effectively deoxidized to the nitrogen and the oxygen. Furthermore, the front and back secondary air supply pipes are generally controlled by a single switch such that it is not advantageous for cleaning the exhaust gas by oxidizing and deoxidizing the exhaust gas synchronously.
Furthermore, the conventional exhaust gas purifiers place the catalyst converters in the chamber, so it is not advantageous of the locomotives, which have a limit space. The cost of processing the exhaust pipes increases.
What is needed, is to provide an exhaust gas purifier, which can effectively clean the exhaust gas exhausted from an engine of a locomotive.

BRIEF SUMMARY

To solve the conventional problems, one objection of the present invention is provided an exhaust gas purifier used in an engine of a locomotive, which can synchronously or separately supply secondary air of two supply pipes to catalyst and take actions with the catalyst, to synchronously take oxidation and reduction with the exhaust gas, in order to improve a purifying efficiency of the catalyst.
Another objection of the present invention is provided a plurality of converter covered with catalyst and arranged in a silencer connected with an exhaust pipe, in order to save spaces.
To achieve the above objections, a exhaust gas purifier used in an engine of a locomotive in accordance with a preferred embodiment, which is arranged between an exhaust pipe of the engine and a silencer connecting to the exhaust pipe, includes a front supply pipe and a back supply pipe configured for supplying secondary air, at least two catalyst converter in the silencer, before the secondary air, and after the back supply pipe, and at least one back catalyst converter arranged in the silencer and after the back supply pipe. The front supply pipe connects with the exhaust terminal of the engine, and the back supply pipe connects with the silencer. The at least two catalyst converter includes at least one front catalyst converter for oxidation and at least one middle catalyst converter for reduction, a dissipating-heat distance defined between the front catalyst converter and the middle catalyst converter.
The exhaust gas purifier further includes a solenoid valve or a flow control valve arranged on the back supply pipe and controlling the time of supplying the secondary air from the back supply pipe into the silencer. When an actual rotating speed or an actual temperature of the engine is low, the solenoid valve or the flow control valve opens to guide the secondary air from the back supply pipe into the silencer such that the back catalyst converter makes the oxidation reaction with the exhaust gas to cooperate with the front catalyst converter for further oxidizing the noxious carbon monoxide and the hydrogen carbide of the exhaust gas. When the actual rotating speed or the actual temperature of the engine is high, the solenoid valve or the flow control valve closed directly or gradually to prevent the secondary air guiding from the back supply pipe into the silencer such that the back catalyst converter makes the reduction reaction with the exhaust gas to cooperate with the middle catalyst converter for further disoxidizing the noxious nitrogen oxide of the exhaust gas.
The present exhaust gas cleaning purifier uses the plurality of catalyst converter in the silencer to make the oxidation reaction and the reduction reaction synchronously. Furthermore, the exhaust gas cleaning purifier use the back catalyst converter to increase the efficiency of oxidizing the carbon monoxide and the hydrogen carbide of the exhaust gas if the actual rotating speed or the actual temperature of the engine is low and the carbon monoxide and hydrogen carbide are easy to be generated. The back catalyst converter also increases the efficiency of disoxidizing the nitrogen oxide of the exhaust gas if the actual rotating speed or the actual temperature of the engine is high and the nitrogen oxide is easy to be generated. Therefore, the exhaust gas cleaning purifier can effectually increases the purifying efficiency of the catalyst.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the various embodiments disclosed herein will be better understood with respect to the following description and drawings, in which like numbers refer to like parts throughout.

FIG. 1 is a schematic view of a exhaust gas purifier in accordance with a first preferred embodiment of the present invention.

FIG. 2 is a schematic view of a exhaust gas purifier in accordance with a second preferred embodiment of the present invention.

FIG. 3 is a schematic, operating view of the exhaust gas purifier of FIG. 1.

FIG. 4 is a schematic view of a exhaust gas purifier in accordance with a third preferred embodiment of the present invention.

FIG. 5 is a schematic view of a exhaust gas purifier in accordance with a fourth preferred embodiment of the present invention.

DETAILED DESCRIPTION

Reference will now be made to the drawings to describe a preferred embodiment of the present exhaust gas cleaning, in detail.
Referring to FIGS. 1, a exhaust gas purifier in accordance with a first preferred embodiment of the present invention is shown. The exhaust gas purifier is arranged between an exhaust pipe 2 connected with an exhaust terminal of the engine 1 and a silencer 3 connecting with the exhaust pipe 2. The exhaust gas purifier includes a plurality of catalyst converters 61, 62 and 63. The plurality of catalyst converters 61, 62 and 63 have a catalyst covering therein. The catalyst includes Pd, Pt, Rh, etc. The plurality of catalyst converters 61, 62 and 63 connect in series in the silencer 3 via the exhaust pipe 2 and a plurality of connecting pipes 21 and 22. The exhaust gas purifier further includes a front supply pipe 4 and a back supply pipe 5 configured for supplying secondary air. The front supply pipe 4 connects with the exhaust terminal of the engine 1. In this exemplary embodiment, the exhaust terminal of the engine 1 includes exhaust gas exhausting routes from an exhaust manifold 15 to the exhaust pipe 2 and the silencer 3. The front supply pipe 4 connects to the exhaust manifold 15 (as shown in FIG. 1), or connects to the exhaust pipe 2 before the silencer 3(as shown in FIG. 2). The back supply pipe 5 is communicated with the connecting pipe 22 of the silencer 3. The secondary air use the intermittent negative pressure produced from the exhaust terminal by operating the engine 1 as a power source to transmit continuously to the exhaust pipe 2 before the silencer 3 and the silencer 3 via the front supply pipe 4 and the back supply pipe 5 respectively.
Among the plurality of the catalyst converters 61, 62 and 63 arranged in the silencer 3, at least two catalyst converters 61 and 62 are arranged between the front supply pipe 4 and the back supply pipe 5. The catalyst converters 61 is a front catalyst converter configured for mainly making an oxidation reaction and the catalyst converter 62 is a middle catalyst converter configured for mainly making a reduction reaction. Furthermore, a dissipating-heat distance H (as shown in FIGS. 1 and 2) is defined between the front catalyst converter 61 and the middle catalyst converter 62 such that the heat produced by the oxidation reactions between the front catalyst converter 61 and the exhaust gas, will not transmit to the middle catalyst converter 62 and influence the reduction reactions. Furthermore, at least one back catalyst converter 63 is arranged in the silencer 3 and after the back supply pipe 5.
The following will present the operation principle of the exhaust gas cleaning.
When the engine operates, the secondary air is pressed by the intermittent negative pressure, and continuously guided into the exhaust pipe 2 and the connecting pipe 22 via the front supply pipe 4 and the back supply pipe 5 to supply enough oxygen to the front catalyst converter 61 and the back catalyst converter 63. The catalyst in the front catalyst converter 61 can make an oxidation reaction with the exhaust gas having an air-fuel ration more than 14.7. The noxious carbon monoxide and the hydrogen carbide are sufficiently oxidized into the innoxious carbon dioxide and the water. Then, since the middle catalyst converter 62 is arranged after the front catalyst converter 61 and the oxygen supplied from the front supply pipe 4 is consumed in a great measure in the front catalyst converter 61, the exhaust gas cleaned by the front catalyst converter 61 has an air-fuel ration less than 14.7, and the exhaust gas makes a reduction reaction with the catalyst in the middle catalyst converter 62 such that the nitrogen oxide is deoxidized into the nitrogen and the oxygen. Lastly, the exhaust gas cleaned by the front catalyst converter 61 and the middle catalyst converter 62, is mixed with the secondary air supplied from the back supply pipe 5 such that the exhaust gas has an air-fuel ration more than 14.7, and passes through the back catalyst converter 63 to make the oxidation reaction with the catalyst in the back catalyst converter 63 for further oxidizing the remnant carbon monoxide and the hydrogen carbide into the innoxious carbon dioxide and the water. Therefore, the exhaust gas purifier can increase the efficiency of the oxidation and the reduction.
Furthermore, in this exemplary embodiment, the exhaust gas purifier further includes a solenoid valve 7 arranged on the back supply pipe 5 under the condition that the front supply pipe 4 guides continuously the secondary air into the exhaust pipe 2. The solenoid valve 7 connects to a check valve 51 and is controlled by an engine control unit 10. The engine control unit has a predetermined speed C, and a speed sensor 12 is arranged on a wheel under the engine 1 or a throttle valve for controlling the accelerograph to be configured for sensing the actual rotate speed of the engine. The actual rotate speed of the engine is transmitted to the engine control unit 10 to compare with the predetermined speed C. The predetermined speed C can be determined by a critical speed of the locomotive, which is obtained by measuring the output of the carbon monoxide and the hydrogen carbide of the exhaust gas. If the engine operates in an idle speed, the exhaust gas has much output of the carbon monoxide and the hydrogen. Therefore, the predetermined speed should be higher than the idle speed. If the actual rotate speed of the engine is lower than the predetermined speed, that is the outputs of the carbon monoxide and the hydrogen carbide of the exhaust gas are larger than the nitrogen oxide, the solenoid valve 7 opens to guide the secondary air from the back supply pipe 5 into the back catalyst converter 63 such that the catalysts in both of the front and back catalyst converter 61, 63 can synchronously oxidize the carbon monoxide and the hydrogen carbide of the exhaust gas. If the actual rotate speed is higher than the predetermined speed, that is the outputs of the carbon monoxide and the hydrogen carbide of the exhaust gas is low and the nitrogen oxide of the exhaust gas should be removed, the solenoid valve 7 closes such that the secondary air cannot be guided from the back supply pipe 5 to the back catalyst converter 63. The noxious carbon monoxide and the hydrogen carbide are oxidized into the carbon dioxide and the water by the front catalyst converter 61, and then the nitrogen oxide of the exhaust gas is deoxidized into the nitrogen and the oxygen by passing through the middle catalyst converter 62 and the back catalyst converter 63. Therefore, the exhaust gas purifier has an improved purifying efficientcy of the exhaust gas.
Furthermore, the present invention can also set a predetermined temperature T instead of the predetermined speed. Especially in the condition that the front supply pipe 4 guides duratively the secondary air into the exhaust pipe 2, a flow control valve 8 is arranged on the back supply pipe 5 (as shown in FIG. 5), and connects to the check valve 51 to be controlled by an engine control unit 13. The predetermined temperature is set in the engine control unit 13 and a temperature sensor 14 is arranged at the exhaust terminal of the engine 1 to be configured for sensing the actual temperature of the exhausting exhaust gas, and transmits the actual temperature to the engine control unit 13 to compare with the predetermined temperature T. The predetermined temperature T is determined by measuring the locomotive. Generally, a locomotive has an exhaust volume in a range of 50 C.C. to 1000 C.C. such that the normal exhaust temperature of the engine is in a range of 200° C. to 900 degrees centigrade. If the actual temperature of the engine is higher than 200° C., the exhaust gas has much carbon monoxide and the hydrogen carbide. Therefore, the predetermined temperature should be higher than 200° C. to obtain same effects.
The above description is given by way of example, and not limitation. Given the above disclosure, one skilled in the art could devise variations that are within the scope and spirit of the invention disclosed herein, including configurations ways of the recessed portions and materials and/or designs of the attaching structures. Further, the various features of the embodiments disclosed herein can be used alone, or in varying combinations with each other and are not intended to be limited to the specific combination described herein. Thus, the scope of the claims is not to be limited by the illustrated embodiments.

Claims

1. An exhaust gas purifier of engine used in a locomotive, which is arranged between an exhaust pipe of the engine and a silencer connecting to the exhaust pipe, comprising:

a front supply pipe and a back supply pipe configured for supplying secondary air, the front supply pipe connecting with an exhaust terminal of the engine, and the back supply pipe connecting with the silencer;

at least two catalyst converter in the silencer arranged between the front supply pipe and the back supply pipe, the at least two catalyst converter comprising at least one front catalyst converter for oxidation and at least one middle catalyst converter for reduction, a dissipating-heat distance defined between the front catalyst converter and the middle catalyst converter; and

at least one back catalyst converter arranged in the silencer and after the back supply pipe.

2. The exhaust gas purifier as claimed in claim 1, further comprising a solenoid valve arranged on the back supply pipe and controlled by an actual rotating speed received by an engine control unit, when the actual rotating speed is lower than a predetermined speed of an engine control unit, the solenoid valve opens, and when the actual rotating speed is higher than the predetermined speed, the solenoid valve closes.

3. The exhaust gas purifier as claimed in claim 2, wherein the predetermined speed is higher than an idle speed.

4. The exhaust gas purifier as claimed in claim 2, wherein the back catalyst converter takes the oxidation with the exhaust gas when the solenoid valve opens, and the back catalyst converter takes the reduction with the exhaust gas when the solenoid valve closes.

5. The exhaust gas purifier as claimed in claim 1, further comprising a flow control valve arranged on the back supply pipe and controlled by an actual exhaust temperature of the engine received by an engine control unit, when the actual exhaust temperature is lower than a predetermined temperature of the engine control unit, the flow control valve opens, and when the actual exhaust temperature is higher than the predetermined temperature, the flow control valve closes gradually or closes completely.

6. The exhaust gas purifier as claimed in claim 5, wherein the predetermined temperature is higher than 200° C.

7. The exhaust gas purifier as claimed in claim 5, wherein the back catalyst converter takes the oxidation with the exhaust gas when the flow control valve opens, the back catalyst converter takes the oxidation and the reduction synchronously when the flow control valve closes gradually, and the back catalyst converter takes the reduction reaction with the exhaust gas when the flow control valve closes completely.