Device and method of monitoring efficiency of car-loaded catalyst converter

The invention relates to the monitoring of the catalyst Efficiency in the treatment of exhaust gases from an Ver internal-combustion engine. In particular, the inventions relates tion fuel control of a closed air / Fuel control loop of an internal combustion engine, with the upstream and downstream of a cata- tors arranged exhaust gas oxygen sensors out (EGO) is equipped with a periodic onboard About monitoring the efficiency of the catalyst.

It is known that the efficiency or the effect ability of a catalyst in the treatment of exhaust gases an internal combustion engine remarkably by the Ratio of air to fuel is influenced, the the machine to be supplied. In a stoichiometric rule ratio of catalytic Umwandlungswir ciency for the oxidation and the Reduktionsum conversions high. The stoichiometric air / fuel ratio is defined as the ratio of air to Fuel that to at a perfect combustion perform a complete consumption of the fuel would. The air / fuel ratio lambda of an air / Fuel mixture is the ratio of

<ul><li>(A) the air weight amount divided by the fuel weight amount actually at a time supplied to the engine or the air supplied Fuel to</li><li>(B) the stoichiometric air / fuel ratio.</li></ul>

The use of closed fuel loop systems is known to make the air / fuel ratio in a narrow range around the stoichiometric ratio to hal th, as a conversion window. There are CLOSED sene fuel loop systems are known, each a before and arranged behind the catalyst EGO use sensor to detect the air / fuel ratio in within to keep the conversion window.

It is further known that the efficiency or Effectiveness of a catalytic conversion by the influenced oxygen storage ability of the catalyst becomes. A good working catalyst lowers Sauer concentration fluctuations in the exhaust stream. On System for testing the catalyst efficiency, the in SAE paper no. 900 062, "Detection of Catalyst Perfor mance Using On-Board Diagnostics ", has been proposed, uses two exhaust gas oxygen sensors, one upstream ward and a downstream of the catalyst to the Oxygen content in the exhaust gas to detect. ver The system applies test signals in the form of air / fuel Ver hältnisschwingungen on both sides of stoichiometry in predetermined amounts or frequencies by Fuel control system faults are caused. By Comparison of the change in the response patterns between the upstream and the downstream EGO Sensor may be a statement about the catalyst efficiency be made.

From DE-41 22 702 A1 is a Katalysatordegradationsdiagnosevor device for an air-fuel ratio control system is known in the catalyst degradation are thus reliably detected can in that a front oxygen sensor output and a rear Oxygen sensor output before and found behind a catalyst will. There are air-fuel ratio correction coefficient based on basic feedback control constants and correction values accordingly rich and lean air-fuel ratio conditions determined and periods and amplitudes of the air-fuel ratio Correction coefficients measured. It is a fat Catalyst diagnostic level value higher than a richer air Fuel ratio feedback control level value set, and a lean catalyst diagnostic level value is lower than a lean air-fuel ratio feedback regulation level value adjusted so that the catalytic converter diagnosis fat level value increases and the lean catalytic converter diagnosis level value decreases when the product out period and amplitude of the air-fuel ratio Correction coefficient increases, and it becomes a condition given, when it is determined that the catalyst is degraded.

From DE 41 12 478 A1 discloses a method and an apparatus for Assessing the state of aging of a catalyst, the exhaust gas, the a lambda-controlled internal combustion engine is supplied known wherein the lambda values ​​measured before and after the catalyst, wherein the smallest possible influence of operating conditions on the calculated aging state value is reached, characterized in that examines whether a control oscillation of the lambda value before Catalyst from rich to lean or vice versa the lambda value behind the catalyst shows a corresponding transition and, if the case is that the catalyst gas flowing through mass flow is determined, the time integral of the product of gas mass flow and lambda value is calculated before the analyzer, the temporal Integral of the product of the gas mass flow and lambda value behind the Catalyst is calculated, and as a measure for the aging state of the Catalyst either the difference between the two integral or the quotient of the two integral or quotient of the Difference and one of the two integral is used.

The invention is based on the object, a method for accurate and reliable determination of the catalyst to create efficiency, in particular for a Bordei genenes system which is suitable, one in an overall fuel control system Internal combustion engine to be inserted.

This object is achieved by a method and a Device having the features of independent claims 1 or 11 dissolved.

With the invention, an on-board process for Monitoring the catalyst efficiency with respect to the geschaf exhaust treatment of a combustion engine fen. The catalyst efficiency is determined by measuring a Umwandlercharakteristik based on the treatment efficiency of hydrocarbon (HC) specifically to the oxygen storage capacity of Kata lysators. Advantageously, this is erfindungsge Permitted method for controlling the air / fuel behaves certi- ficate an air / fuel mixture which Ver one internal-combustion engine is supplied to the treatment the exhaust of the engine and for periodic imple tion of an on-board monitoring of catalyst We Kung grades provided in the exhaust gas treatment. The Exhaust is from the engine to the catalytic converter by upstream exhaust pipe supplied, wherein a first EGO sensor device is exposed to the a first EGO signal which one of the sour has oxygen content of the exhaust gas corresponding value. The Exhaust gas downstream of the catalyst by a out second exhaust pipe, where it a second EGO The sensor device is exposed to a second EGO Signal which the oxygen content in a the downstream-side exhaust gas has appropriate value. Fuel control devices for controlling the Air operated to fuel ratio, in which Fuel the engine in response to a force Fabric-flow control signal is supplied. The Fuel control device is in normal Betriebsmo dus closed as a 2-EGO fuel control system operated in accordance with a known in the art Technology. For example, in a preferred Embodiment, the fuel flow control signal Fuel control apparatus on the basis of the first EGO sensor generated to the ratio substantially to keep within the limits of an area a mean air to fuel ratio amount define the stoichiometric air / fuel Ratio corresponds. The mean air to fuel Money amount is adjusted or "cut" on the basis of the second, downstream EGO Signal corresponding to the known technology mentioned above nik.

The method further comprises performing a Test the efficiency of the catalyst by subjecting interruption of normal operation mode with reviews for other operating mode of the fuel control device, which a closed fuel control based at least the first EGO signal without the second EGO Signal comprises. be air to fuel disturbances generated with a lean Initial interval with a compared to the stoichiometric air to higher force fuel ratio is set. The meager initial Interval followed by a series rich intervals against above the stoichiometric ratio lower air to fuel ratios which with to lean Intervals alternate. An efficiency value for the Catalyst is based on the number of disturbances determined following the lean initiator interval and are detected from the first EGO sensor device, in Compared to the number, the second one of the EGO sensor device are detected. The efficiency value is then vergli with a predetermined stored value chen, that of an acceptable minimum efficiency Catalyst equivalent. In the event that the comparison the efficiency value with the stored value indicating that the catalyst efficiency below the minimum acceptable value is, can be a catalyst Error signal or eingelei another measure tet are. After the completion of the test mode the interference is terminated and the fuel control device in turn in the normal operation mode as a 2 EGO sensor fuel control system operated.

bring Advantageous embodiments of the invention remarkable advantages, especially when bordeige NEN monitoring the efficiency of a catalyst, in particular a three-way catalyst. Such prior ferred embodiments which further detail below describes see a 2-EGO closed force fuel control system with a periodic onboard Catalyst Monitor before. Especially when effected this embodiment, the lean Initial interval a increased accuracy and reliability. The amplitude and the frequency and shape to the disturbances of the air Fuel ratio are at an existing System easily adjustable, which prior Technology USAGE known techniques and system components det. Further advantages and features of different preferred embodiments will become apparent from the following Disclosure and detailed description.

Various preferred embodiments of the inven tion will be reference to the accompanying drawings wrote.

It shows:

<b>Fig.</b> 1 is a schematic view of a combustion combustion engine of a vehicle with a Device for controlling the air / substance-ratio of the air and fuel mixture used for the machine to treat the engine exhaust gases and the periodic Monitoring of catalyst efficiency in the treatment of exhaust gases according to a prior ferred embodiment of the invention,

<b>Fig.</b> 2 is a control block diagram for the fuel regular, gas treatment and monitoring system of the embodiment of <b>Fig.</b> 1,

<b>Fig.</b> 3 is a diagram showing the output voltage an EGO sensor as a function of air / Fuel ratio LAMBDA shows

<b>Fig.</b> 4 is a flow chart showing the procedure showing steps in the calculation of Fuel flow rate during the FPW Normal operation of the <b>Fig.</b> 1 and 2 apparatus shown be performed,

<b>Fig.</b> 5A is a diagram of the interference Air-to-fuel ratio of the Test operating mode of the system of <b>Fig.</b> 1 and 2,

<b>Fig.</b> 5B is a diagram in accordance with <b>Fig.</b> 5a, which comprises Disturbances in the upstream EGO sensor output shows

<b>Fig.</b> 6 is a flow chart showing the procedure showing steps in carrying out the a potency test of the catalyst the embodiment according to <b>Fig.</b> 1 and 2 in Conjunction with the overall fuel Strö mungs control procedures are carried out and

<b>Fig.</b> 7 is a flow chart showing the procedure steps shows the fuel flow rate to calculate and a catalyst About monitoring in connection with the execution form according to <b>Fig.</b> 1 and 2 perform.

The skilled artisan will recognize from the foregoing that the prior lying invention in an apparatus, a method and a system for periodic onboard surveil chung or diagnosis of the efficiency of a cata- sector with respect to the treatment of the exhaust gases of a Burn voltage motor can be used. The terms "we ciency "and" effectiveness "are interchangeably used to mean any appropriate measure or any suitable determination of the effectiveness of the Kata lysators. Thus, the catalyst described above Efficiency value determined stored or expressed are, as a ratio, a portion or the like of disorders true genome of the first EGO sensor men were compared with those from the second EGO Sensor were perceived. With "periodically" is gele sionally or intermittently meant, for example, one or more times after the operation for a Non-operating phase is resumed. In this Context, the reference to the initialization tion of the test or the test phase during the wesent union uniform operation of the machine to start the test when the engine in a closed 2- EGO sensor control operation is, advantageously under normal speed and load conditions, and not necessarily mean that the machine under such must remain conditions or during the entire planned test phase in an equilibrium status ver must remain.

the catalyst monitoring is As stated above in advantageously used in embodiments the 2-EGO sensor closed fuel Regelsy system having both an upstream side as well as use a downstream EGO sensor and an adaptive upstream EGO switching point (advantageously HEGO) exhibit. Such fuel Control systems are known in the art and can among Consideration of the disclosure and description of the present invention in a simple manner to imple tion of the above-board Katalysatorüberwa chung be adapted. Suitable fuel control systems are described for example in US-PS 39 39 654, Creps and in US-PS 40 27 477, Storey, their Disclosures in the following by reference. Each these patents describes a closed 2-EGO sensor Fuel control system, wherein a first control loop an upstream EGO sensor and a propor tionalregler includes. comprises a second control loop a downstream EGO sensor and a double integrator controller. Other such systems are open disclosed in US-PS 48 31 838, Nagai et al and U.S. Patent No. 48 40 027 Okumura, which each have a proportional and Integral (PI) controller in a first control loop an upstream EGO sensor is used. On the Disclosures of both publications will hereinafter Referring. In an embodiment of the systems described in the Nagai et al and Okumura disclosed patents, are adjustable parameters of the PI controller on the Based on the output of a downstream EGO Sen sors modified. include The modifiable parameters a feed amount or a decrease and an Integra tion amount or threshold for a Regelgrenz- Cycle. Other control system parameters, such as Time delay and reference voltage can also on the basis of the output of a downstream-side EGO sensor can be modified. The output of the current upstream side EGO sensor can also generating a second air / fuel ratio Korrekturbe Treaty can be used which in a main fuel Control equation is used.

Other known fuel control systems with double-EGO Sensors of which an upstream and a current is disposed downstream of a catalyst, which for Suitable applications for the inventive design are, have a cascade control scheme, wherein a Signal of the downstream EGO sensor with a Comparison signal is supplied to a summer. Of the Output of the adder is a first PI controller supplied leads. An output signal of the upstream EGO Sensor will together with the output of the first PI-Reg Jewellers a second summer fed. The output of second summer is a second PI controller supplied lead, which then the return signal for regulating the generating air / fuel ratio of the engine. In other suitable method is to both totalizer Reference signal applied. The output of the first PI The controller is not applied to the second summer, but regulates instead the parameters of the second PI controller. This method is as a control parameter known as the parameters of the second controller in turn are controlled by the output of the first regulator.

For purposes of description and not of limitation subsequently be advantageous embodiments with Double EGO fuel control systems, procedures and described systems for an internal combustion engine ben, which the onboard catalyst Überwachungsas pect of the invention in a 2 EGO fuel Regelvor havedirection. In such a preferred embodiment examples that described in detail below be, is an internal combustion engine with a Catalyst and two EGO sensors are provided, wherein an upstream and the other downstream of the The catalyst is arranged. The fuel control system includes a first comparator for generating a first signal from the output signal of the upstream side EGO sensor. Such first signal has a constant absolute value (for example, "1"), ver changes, however, in sign as a Function of the output of the upstream side EGO sensor. A second comparator, or, alternatively, a restriction device, generates a second Signal as a function of the downstream EGO Sensor signal. The second also has a constant Absolute value, however, varies in accidentals Chen's as a function of the downstream EGO Sensor output signal. A correction device a high pass filter, which to the first signal REA giert, generates a third signal. An apparatus for Connecting the scaled second signal with the DRIT th signal generates a fourth signal and a control device responsive to a fourth signal using the PI controller, generates an air / fuel Ratio correction signal. Preferably comprises Control system further comprises a device for open Rege development of an air-fuel mixture during limited hours ter phases independent of the EGO sensor output signals is, for example, during the initial operation of the Engine, in which one or both EGO sensors still have not reached operating temperature.

The system has a normal operating mode and corre accordingly the onboard catalyst monitoring aspect of present invention provides a test mode. While the latter mode, the stromabwärtsseiti of the produced gen EGO sensor signal by a fault signal replaced, as described above.

The fault signal is generated by a signal generator in produces a per se known manner. The signal generator is preferably as a functional element of the machine regular computers designed. The fuel flow Control signal during the test mode based on (a) the Saturated / lean switching of the upstream EGO-Sen sors in a conventional manner by a mid air Fuel ratio value corresponding to the stoichiometric Ver ratio corresponds to as downstream side of the EGO sensor a before initiating the test mode placed or "cut" and b) the interference signal, comprising a lean initial interval signal to the Ratio of calls to fuel the establishment of a to increase lean baseline, followed by alternate the satellite-lean disturbance signals. The outputs of the upstream and downstream EGO Sensors are then evaluated in the test interval. Spezi ell is the number of such disorders of the upstream EGO sensor in the upstream side exhaust were recorded, with the number of disturbances gene compared, the downstream side of the EGO Sensor in the exhaust gas downstream side (ie, stream were detected downstream side of the catalyst). Naturally the skilled artisan recognizes that for counting the interference rather independent sensors as EGO sensors of fuel Control system should be used. The skimmed Initial baseline is in preferably for 1 to 10 seconds furnishings, particularly preferably for 5 Seconds, whereby the lean Initial interval signal the Air to fuel ratio, preferably 3% to 7% increase, particularly preferably bezo by 5% corre settings to the average fuel ratio value accordingly stoichiometry. The immediately following series alternating Satt- and skimmed disorders are in front preferably also by 3% to 7% to the average air to fuel ratio.

The alternating disturbances are not necessarily symmetrical about the average value. Short pulses from 5% to 7% richer than the stoichiometric behaves nis can with longer pulses of only 3% to 5% leaner alternate, or vice versa. The shape of the Pulses may be a rectangular waveform or a Around waveform such as a sinusoidal wave form. The duration of the alternating interference is present preferably between 50 and 200 msec., in particular preferably at 100 msec. for conventional driving convincing motorsysteme.

In case of excessive length burn too many saturated pulses stored in the catalyst oxygen and detected in the downstream side exhaust, leading to rejection a functioning se catalyst results. In front Preferably the alternating disorders have a Fre frequency of 2 Hz to 10 Hz. It is obvious that this frequency is higher than the 1 Hz frequency of the motor fabric-usually limit cycle, which is typical for known closed fuel control systems herkömmli cher machines. During a typical 20-second Test mode phase is a 5-second interval for skimmed Presetting of the catalyst followed by Sattstörun gen used, dealing with skimmed disorders in a Fre frequency from 2 Hz to 5 Hz in the remaining 15 seconds alternate. Thus, in a typical 20-second Test after initial 5-second Magerinterval <b>30</b> to <b>75</b> alternating Satt- and skimmed disorders Runaway be, leads yielding a statistically significant obtained based on the catalyst efficiency test. Of the resulting alternate on the comparison of the number interference that upstream and downstream of the Catalyst were recorded, repre-based value Animal T catalyst conditions and is before a certain stored value compared, which a Efficiency-effectiveness or limit defined. If Comparison of a catalyst efficiency below the indicating the limit value, an error signal is generated.

As in <b>Fig.</b> 1, a microcomputer <b>100</b> to Controlling an air / fuel ratio used, which an internal combustion engine <b>102</b> is supplied. The microcomputer <b>100</b> comprises a central processing unit (CPU) <b>104</b>, A read-only memory (ROM) <b>106</b> for Spei Chern whose main power control routine and other Rou routines, such as a Kraftstoffströmungsrou tine and tuning constants, lookup tables, etc., access memory (RAM) <b>108</b> and conventional A gangs- / output interface (I / O) <b>110</b>, The average put <b>110</b> include analog / digital converter (A / D) for Converting various analog input signals, digi tale inputs, digital / analog converter (D / A) to Encrypt development of various digital outputs and Digital outputs.

The microcomputer <b>100</b> further comprises conventional Ele elements, such as a timing generator and a device for Generating various timing signals, counters, drivers and the like. The microcomputer <b>100</b> controls the air / fuel Ratio by operating injector drivers <b>112</b> in Triggered by actions of the operator and variable operating conditions and parameters of machine <b>102</b>, The microcomputer<b>100</b> gathers Eingangspa parameters and performs calculations of control signals in a specified collection interval DELTA T (AT), as for example, 20 msec., from. When the microcomputer<b>100</b> having a variable sampling rate, a timer should be used, which a time measurement between two perform successive samplings and a measured sampling time DELTA T may assign.

The machine <b>102</b> in this particular embodiment such as conventional four-cylinder combustion combustion engine shown which Kraftstoffeinspritzdü sen <b>114</b>. <b>116</b>. <b>118</b> and <b>120</b> which cooperate with a force cloth line <b>121</b> are connected. Each Kraftstoffein injection nozzle is electronically by corresponding signals of the injector drive <b>112</b> activated. Each injection nozzle <b>114</b>. <b>116</b>. <b>118</b> and <b>120</b> remains in herkömmli cher manner with a corresponding combustion cylinder connected. The exhaust gases from the combustion cylinder who over an exhaust manifold <b>122</b> derived and a three-way catalyst <b>124</b> which CO, HC and NO_x Removes impurities in the exhaust gas, and an off puff <b>126</b> pushed out. In the exhaust manifold<b>122</b>, electricity upstream of the catalyst <b>124</b>A first EGO sensor is <b>128</b> (EGO <b>1</b>) For detecting the oxygen concentration in the exhaust gases arranged. In the exhaust pipe<b>126</b>, downstream ward of the catalyst <b>124</b>, A second EGO sensor is <b>130</b> (EGO <b>2</b>) For detecting the oxygen concentration downstream of the catalyst <b>124</b> used. Both EGO Senso reindeer <b>128</b> and <b>130</b> generate output voltage signals, wel che via the analog / digital converter of the I / O interface <b>110</b> be transmitted. Various suitable alterna tive EGO sensors are known in the art, Enclosure Lich heated EGO sensors (HEGO) etc. , In this Connection, reference is made to the discussion in by way of suitable EGO sensors in the US 50 77 970, Hamburg.

A in communication with the inlet manifold <b>134</b> standing air inlet <b>132</b> is used to introduce air behind the throttle plate <b>136</b> into the combustion cylinder. A throttle position sensor <b>138</b> is to produce a throttle position signal TP to the choke fold plate <b>136</b> connected. With the inlet manifold<b>134</b> continues to be a mass air flow sensor <b>140</b> verbun the order of an air flow amount corresponding signal generate MAF which the amount of the machine introduced air stream and a corresponding tempera ture sensor <b>142</b> for generating a the temperature of the introduced air detecting signal TA. By Zylin derblock the machine <b>102</b> is a cooling water temperature sensor <b>144</b> together to generate a signal TW, indicative of the engine coolant temperature. On Crank angle position sensor <b>146</b> is connected to the crankshaft the machine <b>102</b> connected to a Kurbelwinkelpositi onssignal CA of the crank position capture.

An intake pressure MAP, instead of a Luftströ flow quantity sensor <b>140</b> be used in a known Manner to provide an indication of engine load. Other, required for the operation of the machine forth tional components, such as a Zündsy stem, are in <b>Fig.</b> 1 not shown. It is further Note that the invention in an advantageous manner with other types can be used Example , using machines with a different number of cylinders as four, rotary piston machines and the like.

Operation of a 2-EGO closed Sensor fuel regulatory system in the regulation of the air / Kraftstoffver holds isses is the following with particular reference to a control block diagram according to <b>Fig.</b> 2 and the associated chart in <b>Fig.</b> 3 illustrates that the EGO Sensoraus output voltage as a function VEGO of LAMBDA, so the air / fuel ratio relative to stoichiometric rule air / fuel ratio. Although the description refers to a microcomputer implementation, can running the control system with analogue means will.

The output voltages VEGO1 and VEGO2 the upstream ward side EGO1 sensor <b>128</b> and stromabwärtssei term EGO2 sensor <b>130</b> be via an A / D converter in the I / O device <b>110</b> appropriate comparators <b>200</b> and <b>202</b> supplied. At each comparator are the Refe difference signals REF1 and REF2 at which the EGO output voltage at a stoichiometric ratio correspond, VREF, as in <b>Fig.</b> 3 is shown. Each Verglei cher <b>200</b> and <b>202</b> generates an output signal COMP1 or COMP2, which has a constant absolute value, but varies in sign, on depending on the which side of the stoichiometric ratio corresponding EGO output voltage signal, and VEGO1 VEGO2 lies.

The output of the comparator COMP1 <b>200</b> is the saturated / Lean ratio controller <b>204</b> and the PI controller <b>210</b> supplied. The output COMP2 of the second comparator<b>202</b> is an integral controller <b>206</b> supplied. The exit of the integral controller <b>206</b> is the comparator <b>200</b> about a switch <b>296</b> supplied. The desk<b>296</b> is in the Normal mode of operation is closed so that the Ausgangssi signal of the integral controller <b>206</b> for modifying the Ver DC voltage is used, wherein COMP1 determines whether the EGO1 of the upstream EGO Sen sors <b>128</b> is sick or lean. In test mode, the switch <b>196</b> opened to the one reference voltage freeze, at the COMP1 such determination wherein the value that the comparison voltage at the start of Test mode had, performs.

The output COMP1 of the first comparator <b>200</b> is the PI controller <b>210</b> and continue to the satellite / Magerverhältnisreg ler <b>204</b> supplied. During the normal mode of operation is the output of the PI controller <b>210</b> the Kraftstoffbe bill block <b>212</b> via the switch <b>298</b> supplied. in the Test mode, the output of the saturated / skim regulator <b>204</b> instead of the signal of the PI controller <b>210</b> the force fuel calculation block <b>212</b> via the switch <b>298</b> Trains leads. The PI controller block<b>210</b> is preferably a Pro portional- and integral controller, the output signal a LAMCOR calculated that an air / fuel Behaves represents niskorrekturbetrag. The input values ​​H and G, used to calculate LAMCOR based on COMP1 stored tables 214 are removed are, Return signal and a ramp value for the PI controller and represent settable values ​​of the control system. The Value of the parameters H and G can in panels or tables 214 as a function of engine speed and engine load be saved. The output signal SIG of the function generators <b>300</b> is the fuel calculation block <b>212</b> supplied during the test mode. The three switches<b>296</b>. <b>297</b> and <b>298</b> are functionally within the Mikrocom puter <b>100</b> summarized to share from normal mode switch to test mode. Thus, in the normal mode, the switch <b>296</b> closed, the switch <b>297</b> opened and the desk <b>298</b> connects the PI controller <b>210</b> with the Fuel calculation block <b>212</b>, In test mode, the switch <b>296</b> opened, the switch <b>297</b> closed and the desk <b>298</b> connects the satellite / Magerverhältnisreg ler <b>204</b> with the fuel calculation block <b>212</b>,

The fuel calculation block <b>212</b> calculated in conven Licher, the fuel flow rate FPW, a rule signal for the injector driver <b>112</b>, The calculation can a base value of working in open loop use fuel flow control, which Virtue as a function of engine load / speed feedback is that from the ROM <b>106</b> is removed or the power fuel calculation block <b>212</b> is stored. The calculation statement can be a fuel correction amount use, which, for example, on the Maschinenauf preheating temperature, the battery voltage and the like. based can and also preferably removed from tables is.

A preferred operation of the microcomputer <b>100</b> to Fuel flow control during normal operation mode is on in the following with particular reference the flow chart of <b>Fig.</b> 4 described in detail. Of the Skilled in the art will note that the fuel Regelunterrou tine, as in <b>Fig.</b> 4 is shown, typically a series of subroutines, the repeated each other during engine control who carried out to, for example, in conjunction with Zündfunkenre gelunterroutinen, an EGR subroutine etc.

At the beginning of each sampling interval, the Machine parameters recorded in step 400th The Engine speed and load are then in conven Licher way from the crank position signal CA and the amount of air flow signal MAF calculated. During the Step 402, the basic fuel injection amount FB of the open-loop by taking and Inter interpolation from a speed / load table from the ROM <b>106</b> certainly. In step 404, the Fuel correction amount calculated based on FCOR Input values, for example, the intake air temperature TA and the cooling water temperature TW, the battery voltage and the same.

In step 406 it is checked whether the upstream-side EGO sensor <b>128</b> is sufficiently warmed and / or other conditions are satisfied, to the closed To begin looping. These conditions may include whether the cooling water temperature TW a preselected range has been reached, the Ansauglufttempe temperature TA, an observed EGO sensor switch that since the beginning elapsed time and the like., but are not limited. Further, various Maschi nenbetriebszustände, such as the far geöff designated throttle or prolonged idle, a require open loop control after the closed loop conditions in other ways are met. The machine can simultaneously with the upstream side open and stromabwärtsseiti operated gen open-loop control, ie, the signals of both sensors, the upstream side EGO-sensor and the downstream EGO sensor, be disregarded. This typically takes place takes place when, for example, during a cold Star TES and / or at any other time, the EGO Senso ren are not sufficiently warmed up. Located at the Control system in the upstream open loop fenregelung, it is located in the described here Embodiment also always in the downstream side open-loop control mode. In certain Conditions, an upstream loop control (For example if the control system the upstream side EGO sensor signal and used) take place, while the downstream side an open loop control is carried out. This may for example suc gene when the upstream-side EGO sensor suffi accordingly was heated, while the downstream-side EGO sensor has not been sufficiently warmed up and / or during some hard acceleration conditions, apparent to the skilled man. Under normal standard conditions, the system is in any case an upstream ward side and a downstream side closed Loop control to perform.

If the closed loop control called, in step 408, the air / fuel ratio correction amount LAMCOR calculated, wherein the output of the PI controller <b>210</b> an air / fuel ratio cor represents turbetrag for the closed loop. Ande erwise LAMCOR is set in step 410 to 1. The Frequency of the limit cycle is mainly determined by Para meter of the upstream portion of the rule system determined. The downstream-side EGO sensor however, provides a bias signal, which the Satellite / lean switching point for the upstream side EGO Sensor signal is shifted, whereby the limit cycle to its reference voltage REF1 is asymmetric. to sel ben time, the output of the downstream side EGO2- Sensor around its reference voltage REF2 centered. Of the Output LAMCOR the PI controller brings forth two jumps in front. The first jump occurs when the signal from the upstream EGO sensor, the reference voltage REF1 crosses, and the second jump occurs when the Signal of the downstream EGO sensor his Refe ence voltage REF2 crosses. The logical way of both Step 410 and step 408 leads to step 412, in which the fuel calculation block <b>212</b> on Fuel flow signal FPW based on LAMCOR calculated. The signal FPW drives Kraftstoffein injection nozzle 414. step in step 416, the system performs of the fuel for Flußberechnungsroutine Hauptrou tine back.

It goes without saying that during various Maschinenbetriebsmodi, particularly in unterschiedli chen speeds and loads, the calibratable Parameters of the control system for a reenactment optima require len scheme. These parameters include the Reset value H and the ramp value G of the PI controller <b>210</b>, To achieve a recalibration of these parameters, who to a variety of functions or tables (in for example, the table 214 in <b>Fig.</b> 2) with Maschinendr USAGE ehzahlen and load values ​​as input values det. It is further understood that various degree participated, such as Zeitverzögerer or filter can be used to the control system before Auswir effects of radiofrequency EGO sensor switching to protect. Such changes can easily in ver various preferred embodiments of the inventions tion by a specialist in accordance with the present Revelation be performed.

The operation of the system for periodic catalyst monitoring with simultaneous fuel flow control to the machine in the following with reference the <b>Fig.</b> 2, 5A, 5B, 6 and 7 described. A test Inter vall typically begins during the wesentli chen uniform machine operation, duration 20 Seconds. Several attempts may be required, before a valid test exists. One or more valid tests during a given period steady operation can be performed. A surveil chung test begins during normal operation with closed-loop. The term "periodically" is in USAGE of the importance of occasionally or intermittently det, for example, once (or more) at any time point at which the engine operation after a period of non-operation is started again. In this Context means initiating a test period during the substantially uniform operation of the Machine to start the test period, when the machine working in closed loop operation, no need sarily that all engine operating parameters kon must be stant and not necessarily that the machine during the entire provided Testperi ode must remain in the uniform operation.

At the beginning of the test, the switches <b>296</b>. <b>297</b> and <b>298</b> switched into the test mode. Thus, the Off is output signal of the PI controller <b>210</b> by the Satellite / skim regulator <b>204</b> replaced and the signal from the integral controller <b>206</b> is from the comparator <b>200</b> away. The desk<b>297</b> is closed to the fuel calculation block <b>212</b> a test signal SIG from a signal generator, in <b>Fig.</b> 2 as a function generator <b>300</b> referred to feed. As described above, the test signal SIG causes a gear lean interval and the resulting alternating Satellite / lean disorders, preferably as a periodic radio tion with a frequency which is higher than the limit cycle Frequency of the closed-loop fuel control passage ment based on the upstream EGO sensor is. The fault signal can in this sense as a high frequency signal are considered.

It should be noted that the influence of the disturbance signal and the test mode operation to the current Engine power by the operator in ERAL NEN will not be perceived. The value of FPW is the injector drivers <b>112</b> fed and is in first Line by the value of FB determined. The test signal disturbs the value FB only slightly over its stöchiome cal value. As already stated there Satt- and skimmed disorders an asymmetric waveform to the central air to fuel ratio value corresponding to the stoichiometric value corresponding to (last set on the basis of the downstream EGO sensor from switching to the test mode of operation). According to ver various particularly preferred embodiments of the inven tion regulates the fuel control device the Disorders that follow the input skimmed interval, up to a desired satellite / lean ratio (not that must be 1.0) by comparing the time duration of each Satt-disturbance interval angren with one or both collapsing lean disturbance intervals. In this use, is a contiguous interval of satellite interference directly preceding or following directly interval. According to <b>Fig.</b> 5A and 5B alternates a square wave series (for ease of description) of satellite-Symptom ments with the amplitude "a" above the central Air to fuel ratio value of the stöchiome tric corresponds with longer lean disorders lower amplitude "b" from. The amplitudes "a" and "b" are not by the values ​​"c" and "d" (by scale drawn) regulated under 5B. The value "c" is the Time period of a satellite interference, detected by the upstream ward side EGO sensor. The value of "d" is the duration an adjacent lean disturbance. The stromaufwärtssei term Fault counter <b>304</b> can be designed such that it the period of time in a known manner and with the Specialist admitted with means and compares. The front Preference described same direction and entgegenge modifying disturbances in various preferred From leadership examples realized by a closed Loop control of the fuel control system, which measuring and comparing the time duration of adjacent Satt- and lean disorders includes to appropriate percen centage deviations from the mean air to force adjust fuel ratio value.

The signals VEGO1 VEGO2 and the upstream and downstream EGO sensors are to Stö out insurance counters, for example, signal filter and comprise register means. The upstream side Fault counter <b>304</b> counts the air to force fuel ratio disturbances in the upstream side from gas. The downstream side Fault counter<b>302</b> counts Accordingly, the disturbances in the downstream Exhaust. The counts both be a decision block <b>306</b> supplied, which the values ​​in each geeigne th way compares, for example, by calculating the percentage of the downstream side detected upstream ward mutual interference. Decision block ver then compensates the resulting catalyst-activity degree value with a stored value, the so vorbe is true is that it a minimum acceptable efficiency corresponds for the catalyst. The stored value can easily empirically readied by the expert are true and depends on the Maschinensystemcharakte acteristics and the size from the disturbances. to achieve reliable and accurate results are the disorders advantageously for a given machine system configured so that they between a stored value 40% and 60%, preferably 45% yield, the an acceptable catalyst-minimum efficiency ent speaks. Thus generates the decision block, when higher percentages upstream mutual interference in the downstream-side exhaust gas are detected, a Feh lersignal or directs another appropriate measure on.

Optionally, the error signal a light and / or Sound alarm for the operator of the vehicle drive. Furthermore, the existence of an optional Test indicating signal are generated when the test result does not exceed the predetermined value.

The operation of the microcomputer <b>100</b> in Rege ment of fuel flow to the engine <b>102</b> during the Catalyst Monitor is in the flow chart in <b>Fig.</b> 7 explained. At the beginning of each Prüfinter valls the machine parameters in step 700 are on taken. The engine speed and load are in conventionally from a crank position signal CA and a mass airflow signal MAF calculated. currency end of step 702, the basic fuel-A injection amount FB open loop by taking and Interpolation of a speed / load table from the ROM <b>106</b> certainly. In step 704, a Fuel correction amount FCOR calculated Example as based on the warm-up condition of the engine, the intake air temperature TA, the cooling water temperature TW the battery voltage and the like. Some Maschi nenbetriebsbedingungen as a wide open throttle flap or prolonged idling can also be a require open loop fuel control when other closed loop conditions are met. Thus, the requirements to be a closed Loop checks in step 706th Are the Erforder results, enabling an closed loop control of the motor not satisfied control, in step 724 the air to-fuel ratio correction amount LAMCOR 1 set. The step 716 calculates the final FPW fuel flow based on the main fuel Flow equation that described above for normal operation Ben was. In step 718 will fuel Einspritzdü sen excited and in step 720, the return to done Main microcomputer routine.

When the closed loop Kraftstoffregelanforde ments are determined at step 706 to be fulfilled is checked in step 708 whether a catalyst test is required. A test example erforder Lich, if during the current operation of the machine since the start after an inoperative period yet no test has been successfully completed. Is a test necessary, in step 710, the Uniform keitsbedingungen (stead y state) checked. additionally can be checked in step 710 whether additional ago conditions are met. Applicable regulatory ago regulations may uniform vehicle, machinery speed and load conditions, and specify limit, warming up the upstream and prescribe downstream EGO sensors, etc. If all these conditions are not satisfied, it is in Step 712, the test aborted. In step 714, then the air / fuel ratio correction amount for the 2-EGO sensor closed loop fuel Rege tion, as described above, for the normal operating mode calculated. If the conditions are satisfied in step 710, is a catalyst efficiency test by the Step 722 performed, followed by the steps of 716, 718 and 720, as explained above. The return step <b>720</b> the method directly to the start block directly preceding block <b>700</b> or Hauptrou tine to pass through up to block <b>700</b> traced.

The operation of the microcomputer <b>100</b> in step 722 is for carrying out a catalyst efficiency tests in the flowchart in <b>Fig.</b> shown. 6 applicable Regulations may require that the test in a predetermined period of time, for example, in 20 seconds, is completed. Advantageously comprises the microcomputer <b>100</b> for a time means for the elapsed time to monitor for the test. The Timer is updated in step 600th In Step 602, it is checked whether the predetermined duration of the test was reached. If the test duration time is not reached, in step 604, a function generator <b>300</b> aktuali Siert which the periodic test function SIG ready provides. As stated above, an input skimmed interval set before the alternating interference are generated and are counted, preferably from 0.25 to 10 Seconds, typically around 5 seconds. correspondingly is the test since the beginning of time elapsed in step 610 checked. If the elapsed time the predetermined value exceeded, usually 5 seconds, in the Steps 612 and 614 the detectable faults in the upstream and downstream exhaust, as described above, in consideration of the calculation tion blocks <b>302</b> and <b>304</b> according to <b>Fig.</b> 2 counted. Of the Step 616 shows the output to step 716 in the flow in <b>Fig.</b> 7. The method may then in one or more additional cycle or cycles be repeated. After the test interval has expired is as dictated by step 602, in step 618 the catalyst efficiency value calculated typi cally by dividing the total number of counted Disorders that detected in the downstream side exhaust were, by the total number counted in the current upstream-side exhaust gas, and the result is a stored value compared, which is predetermined so that he an acceptable catalyst minimum efficiency equivalent. When prompted, can in Ent decision block <b>618</b> delivering a an error signal are passed as described above in conjunction with decision tion block <b>306</b> according to <b>Fig.</b> 2 described.