Method and apparatus to reduce noxious components in the exhaust gases of internal combustion engines

Claim 2

Method to reduce noxious components in the exhaust gases of internal combustion engine comprising sensing the composition of the exhaust gases from the internal combustion engine and deriving an exhaust composition representative sensed signal; analyzing the sensed exhaust composition signal to determine whether a characteristic thereof falls above or below a predetermined limit value; integrating a representation of the sensed exhaust composition signal in a direction determined by whether the analyzed signal is above or below said limit value; measuring the time during which the integrating step proceeds in a given direction; changing the integration rate if the integration step has extended beyond a predetermined time period; and controlling the composition of the air-fuel mixture being applied to the internal combustion engine in accordance with said integrated sensed signal.

Claim 3

Method according to claim 1, wherein the time measuring step comprises setting a time element at a datum level; determining elapsed time by deviation of said element from the datum level and deriving a control signal after lapse of said predetermined period of time upon said deviation; and utilizing said control signal to control the change of integration rate during said integration step.

Claim 4

Apparatus to reduce noxious components in the exhaust gases of internal combustion engines comprising means (13) sensing the composition of the exhaust gases from the internal combustion engine and deriving an exhaust composition representatIve sensed signal; a first threshold detector (11) responding to said sensed signal and providing an output trigger signal when the sensed signal changes between levels above and below a predetermined threshold level; and an integrating controller (10) connected to control the relative proportion of air and fuel being applied to the internal combustion engine, the threshold detector having its output trigger signal connected to the integrating controller to change the direction of integration of the integrating controller, a timing element (14, 18) triggered by the output trigger signal from the threshold detector and providing a timing output signal indicative of a predetermined time lapse, said timing signal being connected to the integrating controller to change the control characteristics of said controller after said predetermined time has elapsed; said integrating controller providing an integrated output signal for control of said relative proportion of air and fuel in the mixture which is applied to the internal combustion engine.

Claim 5

Apparatus to reduce noxious components in the exhaust gases of internal combustion engines comprising means (13) sensing the composition of the exhaust gases from the internal combustion engine and deriving an exhaust composition representatIve sensed signal; a first threshold detector (11) responding to said sensed signal and providing an output trigger signal when the sensed signal changes between levels above and below a predetermined threshold level; and an integrating controller (10) connected to control the relative proportion of air and fuel being applied to the internal combustion engine, the threshold detector having its output trigger signal connected to the integrating controller to change the direction of integration of the integrating controller, a timing element (14, 18) triggered by the output trigger signal from the threshold detector and providing a timing output signal indicative of a predetermined time lapse, said timing signal being connected to the integrating controller to change the control characteristics of said controller after said predetermined time has elapsed; said integrating controller providing an integrated output signal for control of said relative proportion of air and fuel in the mixture which is applied to the internal combustion engine.

Claim 6

Apparatus according to claim 3, wherein the integrating controller has a variable integration rate; and the integration rate of the integrating controller is increased after the timing output signal has been applied thereto.

Claim 7

Apparatus according to claim 3, wherein the timing circuit (14) comprises a pulse source (17) providing cyclically recurring output pulses; a second integrator (15) connected to integrate the timing pulses; and a second threshold detector (16) supplying a trigger signal and forming said timing output signal when the second integrator has reached a predetermined level.

Claim 8

Apparatus according to claim 5, wherein the pulse source (17) provides output pulses recurring at a rate proportional to speed of the internal combustion engine.

Claim 9

Apparatus according to claim 3, wherein the timing circuit (18) comprises a pulse source (17) providing cyclically recurring output pulses and a pulse counter means (19, 20) counting the pulses to a predetermined count and delivering said timing output signal at said predetermined count of the counter.

Claim 10

Apparatus according to claim 7, wherein the pulse source (17) provides output pulses recurring at a rate proportional to speed of the internal combustion engine.

Claim 11

Apparatus according to claim 4, wherein the integrating controller (10) comprises an operational amplifier (39) having a controllable input impedance (38, 46, 45), the value of the input impedance determining the integration rate.

Claim 12

Apparatus according to claim 9, wherein the input impedance of the operational amplifier (39) of the integrating controller comprises resistance means (38, 46) having two resistance values; and controllable switching means (45) selectively placing the resistance means of one or the other value in circuit with the operational amplifier, the switching state of said controllable switching means being controlled by said timing signal.

Claim 13

Apparatus according to claim 5, wherein the threshold detector (16) comprises an operational amplifier (52); an integrating capacitor (54) connected to the input of the operational amplifier (52); a semiconductor switching element (61) controlling the charging of said capacitor (54) and a second semiconductor switching element (67) controlling the discharge of said capacitor (54), the state of said second semiconductor switching element being controlled by the output signal of said first threshold detector (11).

Claim 14

Apparatus according to claim 11, further comprising a current drain circuit (58) connected in parallel to said capacitor to permit flow of a controlled discharge leakage current.

Claim 15

Apparatus according to claim 3, further comprising a timing circuit connected to said integrating controller and sensing elapsed integrating time of said integrating controller; said timing circuit providing a control signal to said integrating controller after a predEtermined integrating interval has elapsed to change the integration rate of the controller to a higher integration rate.