US5517820A — Exhaust gas purifying apparatus and method for in…

Claim 1

Independent Claim 137 words

An apparatus for purifying an exhaust gas discharged from an internal combustion engine, comprising: a first exhaust gas passage including a nitrogen oxide removing catalyst and a three way catalyst; a second exhaust gas passage including the three way catalyst; a gas flow regulator for selectively directing the exhaust gas to the first and second exhaust gas passages; and a control unit for controlling the gas flow regulator to direct the exhaust gas to the first exhaust gas passage, through the nitrogen oxide removing catalyst and the three way catalyst when temperature of the nitrogen oxide removing catalyst is within a hydrocarbon adsorbing range thereof while the engine is warming up, and to the second exhaust gas passage, through the three way catalyst, when the temperature of the nitrogen oxide removing catalyst exceeds the hydrocarbon adsorbing range.

Claim 2

Independent Claim 137 words

An apparatus for purifying an exhaust gas discharged from an internal combustion engine, comprising: a first exhaust gas passage including a nitrogen oxide removing catalyst and a three way catalyst; a second exhaust gas passage including the three way catalyst; a gas flow regulator for selectively directing the exhaust gas to the first and second exhaust gas passages; and a control unit for controlling the gas flow regulator to direct the exhaust gas to the first exhaust gas passage, through the nitrogen oxide removing catalyst and the three way catalyst when temperature of the nitrogen oxide removing catalyst is within a hydrocarbon adsorbing range thereof while the engine is warming up, and to the second exhaust gas passage, through the three way catalyst, when the temperature of the nitrogen oxide removing catalyst exceeds the hydrocarbon adsorbing range.

Claim 3

Dependent Claim 44 words

An apparatus according to claim 1, further comprising means for determining whether or not the engine is warming up after starting, and means for determining whether or not the temperature of the nitrogen oxide removing catalyst exceeds the hydrocarbon adsorbing range of temperature thereof.

Claim 4

Dependent Claim 29 words

An apparatus according to claim 2, wherein the warm-up determining means comprises means for detecting temperature of at least one of engine cooling water temperature and exhaust gas temperature.

Claim 5

Dependent Claim 74 words

An apparatus according to claim 3, further comprising a sensor for detecting whether an air to fuel ratio of the engine is in a rich, lean or stoichiometric region after completion of the warm-up of the engine, and wherein the control unit controls the gas flow regulator to direct exhaust gas to the second exhaust gas passage when the air to fuel ratio detected by said sensor is in the rich and stoichiometric regions.

Claim 6

Dependent Claim 40 words

An apparatus according to claim 4, wherein the control unit controls the gas flow regulator to direct exhaust gas to the first exhaust gas passage when the air to fuel ratio detected by said sensor is in the lean region.

Claim 7

Dependent Claim 46 words

An apparatus according to claim 5, wherein the control unit controls the gas flow regulator to direct exhaust gas to the second exhaust gas passage when the temperature of the nitrogen oxide removing catalyst exceeds the hydrocarbon adsorbing range thereof, while the engine is warming up.

Claim 8

Dependent Claim 31 words

An apparatus according to claim 6, wherein the control unit compares the detected temperature of at least one of engine cooling water temperature and exhaust gas temperature with a predetermined value.

Claim 9

Dependent Claim 38 words

An apparatus according to claim 8, wherein the nitrogen oxide removing catalyst temperature determining means comprises a sensor for detecting the temperature of one of: the nitrogen oxide removing catalyst and the exhaust gas at an outlet thereof.

Claim 10

Dependent Claim 34 words

An apparatus according to claim 8, wherein the control unit compares the detected temperature of one of the nitrogen oxide removing means and the exhaust gas at the outlet thereof, with a predetermined value.

Claim 11

Dependent Claim 24 words

An apparatus according to claim 9, wherein the control unit compares the air to fuel ratio detected by said sensor, with a predetermined value.

Claim 12

Dependent Claim 61 words

An apparatus according to claim 1, wherein: the-second exhaust gas passage constitutes part of a main exhaust gas passage extended from the engine; the main exhaust gas passage has a bypass exhaust gas passage provided upstream from the three way catalyst; and the nitrogen oxide removing catalyst is provided in the first exhaust gas passage together with the three way catalyst.

Claim 13

Dependent Claim 35 words

An apparatus according to claim 1, wherein the first exhaust gas passage further comprises a hydrocarbon adsorbent other than the nitrogen oxide removing catalyst, the hydrocarbon adsorbent being provided upstream from the three way catalyst.

Claim 14

Dependent Claim 75 words

An apparatus according to claim 12, further comprising a sensor for detecting whether an air to fuel ratio of the engine is in a rich, lean or stoichiometric region after completion of the warm-up of the engine, and wherein the control unit controls the gas flow regulator to direct the exhaust gas to the second exhaust gas passage when the air to fuel ratio detected by said sensor is in the rich and stoichiometric regions.

Claim 15

Dependent Claim 66 words

An apparatus according to claim 12, wherein: the second exhaust gas passage constitutes part of a main exhaust gas passage extended from the engine; the main exhaust gas passage has a bypass exhaust gas passage provided upstream from the three way catalyst; and the nitrogen oxide removing catalyst and the hydrocarbon adsorbent are provided in the first exhaust gas passage together with the three way catalyst.

Claim 16

Dependent Claim 22 words

An apparatus according to claim 14, wherein the control unit is provided at a downstream end of the bypass exhaust gas passage.

Claim 17

Dependent Claim 157 words

Apparatus for cleaning an exhaust gas discharged from an internal combustion engine by means of a three way catalyst disposed in an exhaust passage of said internal combustion engine, said apparatus comprising: at least one sensor for detecting at least an operating temperature of said internal combustion engine; a nitrogen oxide removing catalyst disposed in said exhaust passage upstream of said three way catalyst relative to a direction of exhaust gas flow in said exhaust gas passage; a bypass passage for conveying said exhaust gas around said nitrogen oxide removing catalyst without passing therethrough; a gas flow regulator for selectively causing said exhaust gas to flow through said bypass passage when said at least an operating temperature of said internal combustion engine exceeds a predetermined level, and for causing said exhaust gas to flow through said nitrogen oxide removing catalyst when said at least an operating temperature of said internal combustion engine is below a predetermined level.

Claim 18

Dependent Claim 157 words

Apparatus for cleaning an exhaust gas discharged from an internal combustion engine by means of a three way catalyst disposed in an exhaust passage of said internal combustion engine, said apparatus comprising: at least one sensor for detecting at least an operating temperature of said internal combustion engine; a nitrogen oxide removing catalyst disposed in said exhaust passage upstream of said three way catalyst relative to a direction of exhaust gas flow in said exhaust gas passage; a bypass passage for conveying said exhaust gas around said nitrogen oxide removing catalyst without passing therethrough; a gas flow regulator for selectively causing said exhaust gas to flow through said bypass passage when said at least an operating temperature of said internal combustion engine exceeds a predetermined level, and for causing said exhaust gas to flow through said nitrogen oxide removing catalyst when said at least an operating temperature of said internal combustion engine is below a predetermined level.

Claim 19

Dependent Claim 21 words

Apparatus according to claim 16, wherein said at least an operating temperature comprises a temperature of said nitrogen oxide removing catalyst.

Claim 20

Dependent Claim 26 words

Apparatus according to claim 17, wherein said predetermined level is set at an upper limit of a hydrocarbon adsorbing range of said nitrogen oxide removing catalyst.

Claim 21

Dependent Claim 35 words

Apparatus according to claim 16, wherein said at least one operating temperature comprises a first temperature of said nitrogen oxide removing catalyst, and a second temperature of one of: engine coolant of and exhaust gas.

Claim 22

Dependent Claim 36 words

Apparatus according to claim 19, wherein said gas flow regulator causes said exhaust gas to flow through said bypass passage when either of said first and second temperatures exceeds a respective first and second predetermined level.

Claim 23

Independent Claim 148 words

A method of purifying an exhaust gas discharged from an internal combustion engine provided with a first exhaust gas passage including a nitrogen oxide removing catalyst and a three way catalyst, and a second exhaust gas passage including the three way catalyst, the method comprising the steps of: determining whether or not the engine is warming up after starting; determining whether or not temperature of the nitrogen oxide removing catalyst exceeds a hydrocarbon adsorbing range thereof; and directing the exhaust gas to said first exhaust gas passage through the nitrogen oxide removing catalyst and thereafter through the three way catalyst when temperature of the nitrogen oxide removing catalyst is within the hydrocarbon adsorbing range thereof while the engine is warming up, and to the second exhaust gas passage through the three way catalyst when the temperature of the nitrogen oxide removing catalyst exceeds the hydrocarbon adsorbing range thereof.

Claim 24

Independent Claim 148 words

A method of purifying an exhaust gas discharged from an internal combustion engine provided with a first exhaust gas passage including a nitrogen oxide removing catalyst and a three way catalyst, and a second exhaust gas passage including the three way catalyst, the method comprising the steps of: determining whether or not the engine is warming up after starting; determining whether or not temperature of the nitrogen oxide removing catalyst exceeds a hydrocarbon adsorbing range thereof; and directing the exhaust gas to said first exhaust gas passage through the nitrogen oxide removing catalyst and thereafter through the three way catalyst when temperature of the nitrogen oxide removing catalyst is within the hydrocarbon adsorbing range thereof while the engine is warming up, and to the second exhaust gas passage through the three way catalyst when the temperature of the nitrogen oxide removing catalyst exceeds the hydrocarbon adsorbing range thereof.

Claim 25

Dependent Claim 43 words

A method according to claim 21, wherein the first exhaust gas passage further includes a hydrocarbon adsorbent other than the nitrogen oxide removing catalyst, the hydrocarbon adsorbent being provided upstream from the three way catalyst relative to a direction of exhaust gas flow.

Claim 26

Dependent Claim 62 words

A method according to claim 21, further comprising the steps of: detecting whether an air to fuel ratio of the engine is in a rich, lean or stoichiometric region after completion of the warm-up of the engine; and directing the exhaust gas to the second exhaust gas passage when the detected air to fuel ratio is in the rich and stoichiometric regions.

Claim 27

Dependent Claim 33 words

A method according to claim 23, wherein the exhaust gas directing step directs the exhaust gas to the first exhaust gas passage when the air to fuel ratio is in the lean region.

Claim 28

Dependent Claim 108 words

Method of cleaning an exhaust gas discharged from an internal combustion engine by means of a three way catalyst disposed in an exhaust passage of said internal combustion engine, said method comprising the steps of: sensing at least an operating temperature of said internal combustion engine; selectively passing said exhaust gas through a nitrogen oxide removing catalyst disposed upstream of said three way catalyst relative to a direction of exhaust gas flow, when said at least one operating temperature is below a predetermined level; and selectively causing said exhaust gas to bypass said nitrogen oxide removing catalyst when said at least one operating temperature exceeds said predetermined level.

Claim 29

Dependent Claim 108 words

Method of cleaning an exhaust gas discharged from an internal combustion engine by means of a three way catalyst disposed in an exhaust passage of said internal combustion engine, said method comprising the steps of: sensing at least an operating temperature of said internal combustion engine; selectively passing said exhaust gas through a nitrogen oxide removing catalyst disposed upstream of said three way catalyst relative to a direction of exhaust gas flow, when said at least one operating temperature is below a predetermined level; and selectively causing said exhaust gas to bypass said nitrogen oxide removing catalyst when said at least one operating temperature exceeds said predetermined level.

Claim 30

Dependent Claim 21 words

Method according to claim 25, wherein said at least one operating temperature comprises a temperature of said nitrogen oxide removing catalyst.

Claim 31

Dependent Claim 26 words

Method according to claim 26, wherein said predetermined level is set at an upper limit of a hydrocarbon adsorbing range of said nitrogen oxide removing catalyst.

Claim 32

Dependent Claim 35 words

Method according to claim 25, wherein said at least one operating temperature comprises a first temperature of said nitrogen oxide removing catalyst and a second temperature of one of engine coolant and said exhaust gas.

Claim 33

Dependent Claim 36 words

Method according to claim 28, wherein said step of selectively passing said exhaust gas through a nitrogen oxide removing catalyst is performed when said first and second temperatures are below first and second predetermined levels respectively.

Claim 34

Independent Claim 153 words

An apparatus for purifying an exhaust gas discharged from an internal combustion engine, comprising: a first exhaust gas passage including a nitrogen oxide removing catalyst and a three way catalyst; a second exhaust gas passage including the three way catalyst; means for determining an operating temperature of said internal combustion engine; means for determining a temperature of said nitrogen oxide removing catalyst; and a control unit for causing said exhaust gas to flow through said first exhaust gas passage when said operating temperature of said internal combustion engine is below a first threshold value and said temperature of said nitrogen oxide removing catalyst is below a second threshold value, and for causing said exhaust gas to flow through said second exhaust gas passage when either said operating temperature of said internal combustion engine is above said first threshold or said temperature of said nitrogen oxide removing catalyst is above said second threshold value.

Claim 35

Independent Claim 153 words

An apparatus for purifying an exhaust gas discharged from an internal combustion engine, comprising: a first exhaust gas passage including a nitrogen oxide removing catalyst and a three way catalyst; a second exhaust gas passage including the three way catalyst; means for determining an operating temperature of said internal combustion engine; means for determining a temperature of said nitrogen oxide removing catalyst; and a control unit for causing said exhaust gas to flow through said first exhaust gas passage when said operating temperature of said internal combustion engine is below a first threshold value and said temperature of said nitrogen oxide removing catalyst is below a second threshold value, and for causing said exhaust gas to flow through said second exhaust gas passage when either said operating temperature of said internal combustion engine is above said first threshold or said temperature of said nitrogen oxide removing catalyst is above said second threshold value.

Claim 36

Dependent Claim 44 words

Apparatus according to claim 30, further comprising means for determining an air/fuel ratio of said internal combustion engine, wherein said control unit causes said exhaust gas to flow through said first exhaust gas passage when said air/fuel ratio is above a third threshold value.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1999-05-21	1999-11-20	2000-05-21	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2003-05-21	2003-11-20	2004-05-21	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2007-05-21	2007-11-20	2008-05-21	$7700.00	Window Closed / Lapsed

Exhaust gas purifying apparatus and method for internal combustion engine

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