Oxygen sensor fault detection and response system

Claim 2

In a control system having: oxygen sensing means for sensing oxygen in a monitored area and for providing an oxygen sense signal in response thereto; fault detection means for responding to indicia that said oxygen sensing means has faulted, and for providing a fault signal in response thereto; and control means for receiving said oxygen sense signal and said fault signal, and for selectively providing: closed loop control of an output control signal, based at least in part on said oxygen sense signal; and open loop control of said output control signal upon receiving said fault signal, wherein said open loop control substantially ignores said oxygen sense signal; an improved control system characterised by closed loop reinitiation means for periodically causing said control means, from open loop control of said output control signal and in response to said fault signal, to attempt said closed loop control of said output control signal and, upon attempting said closed loop control and in the absence of said fault signal, for subsequently causing said closed loop control to be maintained.

Claim 3

The improved control of claim l further characterised by confidence measuring means for measuring confidence in said oxygen sensing means based on previously operability thereof and for providing a measure of confidence based thereon, wherein said periodicity of attempting said closed loop control depends, at least in part, upon said measure of confidence.

Claim 4

The improved control system of claim 2 wherein said measure of confidence is increased for each occurrence of an event that indicates operability of said oxygen sensing means, and wherein said measure of confidence is decreased for each occurrence of an event that indicates non-operability of said oxygen sensing means.

Claim 5

The improved control system of claim 3 wherein said closed loop reinitiation means can selectively periodically attempt said closed loop control at a first rate and at a second rate, with said first rate being faster than said second rate.

Claim 6

The improved control system of claim 4 wherein said first rate of periodicity for repeated attempts at closed loop control will result, despite repeated occurrences of said event that indicates non-operability, unless and until said measure of confidence diminishes below a predetermined limit.

Claim 7

The improved control system of claim 3 wherein said measure of confidence comprises a count, wherein: said count is decremented for each occurrence of said event that indicates operability of said oxygen sensing means; and said count is incremented for each occurrence of said event that indicates non-operability of said oxygen sensing means.

Claim 8

The improved control system of claim 6 wherein said count can decrement to only a predetermined lower limit, and can increment to only a predetermined higher limit.

Claim 9

In a fuel delivery system for use with an automobile having an internal combustion engine and an engine coolant system, the fuel delivery system including: temperature sensing means for sensing temperature of engine coolant contained within said engine coolant system and for providing a coolant temperature signal in response thereto; oxygen sensing means for sensing oxygen in a monitored area of said automobile and for providing an oxygen sense signal in response thereto; fault detection means for responding to indicia that said oxygen sensing means has faulted, and for providing a fault signal in response thereto; and control means for receiving said oxygen sense signal, said fault signal, and said coolant temperature signal, and for selectively providing: closed loop control of a fuel delivery control signal, based at least in part on said oxygen sense signal; and open loop control of said fuel delivery control signal upon receiving said fault signal, wherein said open loop control substantially ignores said oxygen sense signal; an improved control system characterised by: confidence measuring means for measuring confidence in said oxygen sensing means based on previous operability thereof and for providing a measure of confidence based thereon; first delay means for causing said control means to delay switching from said closed loop control to said open loop control upon receiving said fault signal, said delay having a duration that depends, at least in part, upon said measure of confidence; and closed loop reinitiation means for periodically causing said control means, while providing open loop control of said output control signal, to attempt said closed loop control of said output control signal, and upon attempting said closed loop control and the in the absence of said fault signal, for subsequently causing said closed loop control to be maintained, wherein said periodicity of attempting said closed loop control depends, at least in part, upon said measure of confidence; second delay means for causing said control means to provide only said open loop control upon initially starting said engine until both said coolant temperature has at least equalled a predetermined limit and a second engine operating parameter has at least equalled a predetermined value, and to thereafter allow said control means to attempt to provide said closed loop control.

Claim 10

In a fuel delivery system for use with an automobile having an internal combustion engine and an engine coolant system, the fuel delivery system including: temperature sensing means for sensing temperature of engine coolant contained within said engine coolant system and for providing a coolant temperature signal in response thereto; oxygen sensing means for sensing oxygen in a monitored area of said automobile and for providing an oxygen sense signal in response thereto; fault detection means for responding to indicia that said oxygen sensing means has faulted, and for providing a fault signal in response thereto; and control means for receiving said oxygen sense signal, said fault signal, and said coolant temperature signal, and for selectively providing: closed loop control of a fuel delivery control signal, based at least in part on said oxygen sense signal; and open loop control of said fuel delivery control signal upon receiving said fault signal, wherein said open loop control substantially ignores said oxygen sense signal; an improved control system characterised by: confidence measuring means for measuring confidence in said oxygen sensing means based on previous operability thereof and for providing a measure of confidence based thereon; first delay means for causing said control means to delay switching from said closed loop control to said open loop control upon receiving said fault signal, said delay having a duration that depends, at least in part, upon said measure of confidence; and closed loop reinitiation means for periodically causing said control means, while providing open loop control of said output control signal, to attempt said closed loop control of said output control signal, and upon attempting said closed loop control and the in the absence of said fault signal, for subsequently causing said closed loop control to be maintained, wherein said periodicity of attempting said closed loop control depends, at least in part, upon said measure of confidence; second delay means for causing said control means to provide only said open loop control upon initially starting said engine until both said coolant temperature has at least equalled a predetermined limit and a second engine operating parameter has at least equalled a predetermined value, and to thereafter allow said control means to attempt to provide said closed loop control.

Claim 11

In a control system having: oxygen sensing means for sensing oxygen in a monitored area and for providing an oxygen sense signal in response thereto; an improved control system characterised by fault detection means for responding to indicia that said oxygen sensing means has faulted, and for providing a fault signal indicative of past operability thereof; control means for receiving said oxygen sense signal and said fault signal, and for selectively providing loop control functions including: closed loop control of an output control signal, based at least in part on said oxygen sense signal, and open loop control of said output control signal upon receiving said fault signal, wherein said open loop control substantially ignores said oxygen sense signal; and variable delay means for causing said control means to delay switching from one of said loop control functions to the other of said loop control functions, wherein the delay is set, at least in part, according to the past operability of said oxygen sensing means indicated by said fault signal.

Claim 12

In a control system having: oxygen sensing means for sensing oxygen in a monitored area and for providing an oxygen sense signal in response thereto; an improved control system characterised by fault detection means for responding to indicia that said oxygen sensing means has faulted, and for providing a fault signal indicative of past operability thereof; control means for receiving said oxygen sense signal and said fault signal, and for selectively providing loop control functions including: closed loop control of an output control signal, based at least in part on said oxygen sense signal, and open loop control of said output control signal upon receiving said fault signal, wherein said open loop control substantially ignores said oxygen sense signal; and variable delay means for causing said control means to delay switching from one of said loop control functions to the other of said loop control functions, wherein the delay is set, at least in part, according to the past operability of said oxygen sensing means indicated by said fault signal.