System for monitoring the efficiency of a catalyst, in particular for motor vehicles

Claim 1

A system for measuring an efficiency of a catalyst through which gas flow is intended to pass, including at least two sensors such as lambda sensors which are disposed in use respectively upstream and downstream of said catalyst in the direction of the gas flow and which generate respective output signals, said system including: first and second calculation means for calculating moving averages of the output signals: third and fourth calculation means each for calculating differences between instantaneous values of the output signals from one of said upstream or downstream sensors and said moving averages of the first and second calculation means, respectively, in order to generate difference signals; fifth calculation means for calculating output efficiency signals having values indicative of the efficiency of the catalyst on the basis of the difference signals or signals derived therefrom; and a warning unit, said warning unit responsive to values of said efficiency signals to generate a warning indicating when said catalyst is operating inefficiently.

Claim 2

A system for measuring an efficiency of a catalyst through which gas flow is intended to pass, including at least two sensors such as lambda sensors which are disposed in use respectively upstream and downstream of said catalyst in the direction of the gas flow and which generate respective output signals, said system including: first and second calculation means for calculating moving averages of the output signals: third and fourth calculation means each for calculating differences between instantaneous values of the output signals from one of said upstream or downstream sensors and said moving averages of the first and second calculation means, respectively, in order to generate difference signals; fifth calculation means for calculating output efficiency signals having values indicative of the efficiency of the catalyst on the basis of the difference signals or signals derived therefrom; and a warning unit, said warning unit responsive to values of said efficiency signals to generate a warning indicating when said catalyst is operating inefficiently.

Claim 14

A system for monitoring efficiency of a catalyst of an internal combustion engine by analysis of upstream and downstream signals, comprising: a first lambda sensor which samples gases upstream of said catalyst and which generates a first input signal; a second lambda sensor which samples gases downstream of said catalyst and which generates a second input signal; a microprocessor having dual input channels, said channels receiving said first and second input signals, each of said channels comprising: a variable-average calculating module which calculates moving averages of the input signals; a difference calculating node which calculates first sets of differences between instantaneous values of the input signals and the moving averages; and a means for receiving said sets of differences and calculating output signals over an operating period of said catalyst; means for calculating efficiency signals indicative of the efficiency of the catalyst on the basis of said output signals; and a warning unit sensitive to said efficiency signals to communicate the condition of said catalyst.

Claim 15

A system for monitoring efficiency of a catalyst of an internal combustion engine by analysis of upstream and downstream signals, comprising: a first lambda sensor which samples gases upstream of said catalyst and which generates a first input signal; a second lambda sensor which samples gases downstream of said catalyst and which generates a second input signal; a microprocessor having dual input channels, said channels receiving said first and second input signals, each of said channels comprising: a variable-average calculating module which calculates moving averages of the input signals; a difference calculating node which calculates first sets of differences between instantaneous values of the input signals and the moving averages; and a means for receiving said sets of differences and calculating output signals over an operating period of said catalyst; means for calculating efficiency signals indicative of the efficiency of the catalyst on the basis of said output signals; and a warning unit sensitive to said efficiency signals to communicate the condition of said catalyst.

Claim 23

A system for monitoring efficiency of a catalyst by analysis of upstream and downstream signals, comprising: a first lambda sensor which samples gases upstream of said catalyst and which generates a first input signal; a second lambda sensor which samples gases downstream of said catalyst and which generates a second input signal; a microprocessor having dual input channels, said channels receiving said first and second input signals, said channels comprising: dual integration paths, one for each input channel, wherein each integration path comprises: a variable-average calculating module which calculates moving averages of the input signals; a first difference calculating node which calculates first sets of differences between instantaneous values of the input signals and the moving averages; a squaring module which squares said first sets of differences and which generates intermediate signals; and an integration module which sums said intermediate signals over a period and which generates output signals; a first comparator which compares the output signals corresponding to the first sensor integration path and a reference threshold value, said first comparator generating fault signals indicating a faulty first sensor; a second difference calculating node which receives the output signals from said integration paths and which determines differences between said output signals; a reciprocal calculating module which determines reciprocals of the output signals from said first sensor integration path; a multiplication node which multiplies said reciprocals and said differences and which generates normalized output signals; a second comparator which compares the normalized output signals and a second reference threshold value, said second comparator generating efficiency signals related to the efficiency of said catalyst; and a warning unit sensitive to said fault signals of said first comparator, said warning unit communicating a faulty condition of said first sensor, said warning unit further sensitive to said efficiency signals to communicate the condition of said catalyst.

Claim 24

A system for monitoring efficiency of a catalyst by analysis of upstream and downstream signals, comprising: a first lambda sensor which samples gases upstream of said catalyst and which generates a first input signal; a second lambda sensor which samples gases downstream of said catalyst and which generates a second input signal; a microprocessor having dual input channels, said channels receiving said first and second input signals, said channels comprising: dual integration paths, one for each input channel, wherein each integration path comprises: a variable-average calculating module which calculates moving averages of the input signals; a first difference calculating node which calculates first sets of differences between instantaneous values of the input signals and the moving averages; a squaring module which squares said first sets of differences and which generates intermediate signals; and an integration module which sums said intermediate signals over a period and which generates output signals; a first comparator which compares the output signals corresponding to the first sensor integration path and a reference threshold value, said first comparator generating fault signals indicating a faulty first sensor; a second difference calculating node which receives the output signals from said integration paths and which determines differences between said output signals; a reciprocal calculating module which determines reciprocals of the output signals from said first sensor integration path; a multiplication node which multiplies said reciprocals and said differences and which generates normalized output signals; a second comparator which compares the normalized output signals and a second reference threshold value, said second comparator generating efficiency signals related to the efficiency of said catalyst; and a warning unit sensitive to said fault signals of said first comparator, said warning unit communicating a faulty condition of said first sensor, said warning unit further sensitive to said efficiency signals to communicate the condition of said catalyst.

Claim 26

A method of measuring an efficiency of a catalyst through which gas flow is intended to pass, including at least two sensors such as lambda sensors, which are disposed respectively upstream and downstream of said catalyst in the direction of the gas flow and which generate respective output signals having respective instantaneous values, said method comprising the steps of: for each sensor, calculating moving averages of said instantaneous values of said output signals; for each sensor, calculating differences between said instantaneous values of said output signals and said moving averages in order to generate difference signals relating to the difference between said instantaneous values and said moving averages; calculating output efficiency signals indicative of the efficiency of the catalyst on the basis of the difference signals or signals derived therefrom; and receiving said efficiency signals at a warning unit, said warning unit responsive to said efficiency signals and generating a warning signal when said catalyst is operating inefficiently.

Claim 27

A method of measuring an efficiency of a catalyst through which gas flow is intended to pass, including at least two sensors such as lambda sensors, which are disposed respectively upstream and downstream of said catalyst in the direction of the gas flow and which generate respective output signals having respective instantaneous values, said method comprising the steps of: for each sensor, calculating moving averages of said instantaneous values of said output signals; for each sensor, calculating differences between said instantaneous values of said output signals and said moving averages in order to generate difference signals relating to the difference between said instantaneous values and said moving averages; calculating output efficiency signals indicative of the efficiency of the catalyst on the basis of the difference signals or signals derived therefrom; and receiving said efficiency signals at a warning unit, said warning unit responsive to said efficiency signals and generating a warning signal when said catalyst is operating inefficiently.