Method for measuring conversion efficiency of catalyst and detecting deterioration thereof with air/fuel ratio sensors
First Claim
1. A method for measuring the conversion rate of a catalyst which converts harmful and toxic components of exhaust gas of an internal combustion engine, comprising the steps of:
- (a) providing an upstream air/fuel ratio sensor and a downstream air/fuel ratio sensor in an exhaust manifold of said engine, said upstream sensor being positioned on the upstream side of the catalyst and said downstream sensor being positioned on the downstream side of the catalyst;
(b) measuring the reduction ratio of an output amplitude of the downstream air/fuel ratio sensor to an output of the upstream air/fuel ratio sensor; and
(c) comparing the reduction ratio with a predetermined mean converted rate of HC, CO and Nox to determine a mean converted rate of the catalyst for HC, CO, and NOx in said exhaust gas.
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Accused Products
Abstract
The invention provides a method for accurately and precisely measuring a converted rate of a catalyst for HC/CO/NOx, NOx, and HC/CO and detecting deterioration using two air/fuel ratio sensors disposed on the upstream and downstream sides of the catalyst. The converted rate of the catalyst is determined based on a predetermined relationship between the mean converted rate and a reduction ratio of output amplitudes of the downstream sensor to the upstream sensor. The catalyst is determined to be deteriorating when the reduction ratio becomes less than a predetermined value.
29 Citations
17 Claims
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1. A method for measuring the conversion rate of a catalyst which converts harmful and toxic components of exhaust gas of an internal combustion engine, comprising the steps of:
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(a) providing an upstream air/fuel ratio sensor and a downstream air/fuel ratio sensor in an exhaust manifold of said engine, said upstream sensor being positioned on the upstream side of the catalyst and said downstream sensor being positioned on the downstream side of the catalyst; (b) measuring the reduction ratio of an output amplitude of the downstream air/fuel ratio sensor to an output of the upstream air/fuel ratio sensor; and (c) comparing the reduction ratio with a predetermined mean converted rate of HC, CO and Nox to determine a mean converted rate of the catalyst for HC, CO, and NOx in said exhaust gas. - View Dependent Claims (2, 3)
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4. A method for measuring the conversion rate of a catalyst which converts harmful and toxic components of exhaust gas of an internal combustion engine, comprising the steps of:
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(a) providing an upstream air/fuel ratio sensor and a downstream air/fuel ratio sensor in an exhaust manifold of said engine, said upstream sensor being positioned on the upstream side of the catalyst and said downstream sensor being positioned on the downstream side of the catalyst; (b) measuring the reduction ratio of an output amplitude of the downstream air/fuel ratio sensor to an output of the upstream air/fuel ratio sensor; (c) determining a mean converted rate of the catalyst for HC, CO, and NOx in said exhaust gas; and (d) comparing the reduction ratio with the predetermined mean converted rate of HC, CO and NOx using a diagram containing a predetermined linear relationship between the reduction ratio and the mean converted rate of HC, CO, and NOx. - View Dependent Claims (5)
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6. A method for measuring the conversion rate of a catalyst which converts harmful and toxic components of exhaust gas of an internal combustion engine for NOx, comprising the steps of:
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(a) providing an upstream air/fuel ratio sensor and a downstream air/fuel ratio sensor in an exhaust manifold of said engine, said upstream sensor being positioned on the upstream side of the catalyst and said downstream sensor being positioned on the downstream side of the catalyst; (b) measuring the reduction ratio of an output amplitude of the downstream air/fuel ratio sensor for a lean air/fuel mixture to an output of the upstream air/fuel ratio sensor for a lean air/fuel mixture; and (c) comparing the reduction ratio with a predetermined mean converted rate of NOx to determine a mean converted rate of the catalyst for NOx in said exhaust gas. - View Dependent Claims (7, 8)
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9. A method for measuring the conversion rate of a catalyst which converts harmful and toxic components of exhaust gas of an internal combustion engine for NOx, comprising the steps of:
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(a) providing an upstream air/fuel ratio sensor and a downstream air/fuel ratio sensor in an exhaust manifold of said engine, said upstream sensor being positioned on the upstream side of the catalyst and said downstream sensor being positioned on the downstream side of the catalyst; (b) measuring the reduction ratio of an output amplitude of the downstream air/fuel ratio sensor for a lean air/fuel mixture to an output of the upstream air/fuel ratio sensor for a lean air/fuel mixtures; (c) determining a mean converted rate of the catalyst for NOx in said exhaust gas; and (d) comparing the reduction ratio with the predetermined mean converted rate of NOx using a diagram containing a predetermined linear relationship between the reduction ratio and the mean converted rate of NOx. - View Dependent Claims (10)
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11. A method for measuring the conversion rate of a catalyst which converts harmful and toxic components of exhaust gas of an internal combustion engine for HC and CO, comprising the steps of:
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(a) providing an upstream air/fuel ratio sensor and a downstream air/fuel ratio sensor in an exhaust manifold of said engine, said upstream sensor being positioned on the upstream side of the catalyst and said downstream sensor being positioned on the downstream side of the catalyst; (b) measuring the reduction ratio of an output amplitude of the downstream air/fuel ratio sensor for a rich air/fuel mixture to an output of the upstream air/fuel ratio sensor for a rich air/fuel mixture; and (c) comparing the reduction ratio with a predetermined mean converted rate of HC and CO to determine a mean converted rate of the catalyst for HC and CO in said exhaust gas. - View Dependent Claims (12, 13)
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14. A method for measuring the conversion rate of a catalyst which converts harmful and toxic components of exhaust gas of an internal combustion engine for HC and CO, comprising the steps of:
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(a) providing an upstream air/fuel ratio sensor and a downstream air/fuel ratio sensor in an exhaust manifold of said engine, said upstream sensor being positioned on the upstream side of the catalyst and said downstream sensor being positioned on the downstream side of the catalyst; (b) measuring the reduction ratio of an output amplitude of the downstream air/fuel ratio sensor for a rich air/fuel mixture to an output of the upstream air/fuel ratio sensor for a rich air/fuel mixture; (c) determining a mean converted rate of the catalyst for HC and CO in said exhaust gas; and (d) comparing the reduction ratio with the predetermined mean converted rate of HC and CO using a diagram containing a predetermined linear relationship between the reduction ratio and the mean converted rate of HC and CO. - View Dependent Claims (15)
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16. A method for measuring the conversion rate of a catalyst which converts harmful and toxic components of exhaust gas of an internal combustion engine, comprising the steps of:
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(a) providing an upstream air/fuel ratio sensor and a downstream air/fuel ratio sensor in an exhaust manifold of said engine, said upstream sensor being positioned on the upstream side of the catalyst and said downstream sensor being positioned on the downstream side of the catalyst; and (b) detecting deterioration of the catalyst when a reduction ratio of an output amplitude of the downstream air/fuel ratio sensor to an output amplitude of the upstream air/fuel ratio sensor becomes less than a predetermined value. - View Dependent Claims (17)
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Specification