GB2201516A - Process and apparatus for testing a lambda measuring probe - Google Patents
Process and apparatus for testing a lambda measuring probe Download PDFInfo
- Publication number
- GB2201516A GB2201516A GB08803821A GB8803821A GB2201516A GB 2201516 A GB2201516 A GB 2201516A GB 08803821 A GB08803821 A GB 08803821A GB 8803821 A GB8803821 A GB 8803821A GB 2201516 A GB2201516 A GB 2201516A
- Authority
- GB
- United Kingdom
- Prior art keywords
- voltage
- measuring probe
- probe
- state
- measuring
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000000523 sample Substances 0.000 title claims abstract description 59
- 238000000034 method Methods 0.000 title claims description 20
- 238000012360 testing method Methods 0.000 title claims description 5
- 239000000203 mixture Substances 0.000 claims abstract description 11
- 238000005259 measurement Methods 0.000 claims description 12
- 230000008878 coupling Effects 0.000 claims description 10
- 238000010168 coupling process Methods 0.000 claims description 10
- 238000005859 coupling reaction Methods 0.000 claims description 10
- 230000001419 dependent effect Effects 0.000 claims description 2
- 206010037660 Pyrexia Diseases 0.000 claims 1
- 230000032683 aging Effects 0.000 claims 1
- 239000000446 fuel Substances 0.000 claims 1
- KRTSDMXIXPKRQR-AATRIKPKSA-N monocrotophos Chemical compound CNC(=O)\C=C(/C)OP(=O)(OC)OC KRTSDMXIXPKRQR-AATRIKPKSA-N 0.000 claims 1
- 230000001360 synchronised effect Effects 0.000 claims 1
- 238000011161 development Methods 0.000 description 10
- 230000018109 developmental process Effects 0.000 description 10
- 238000011156 evaluation Methods 0.000 description 4
- 238000012544 monitoring process Methods 0.000 description 3
- 230000003679 aging effect Effects 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/416—Systems
- G01N27/417—Systems using cells, i.e. more than one cell and probes with solid electrolytes
- G01N27/4175—Calibrating or checking the analyser
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/0004—Gaseous mixtures, e.g. polluted air
- G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
- G01N33/007—Arrangements to check the analyser
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Pathology (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Immunology (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Molecular Biology (AREA)
- Electrochemistry (AREA)
- Combustion & Propulsion (AREA)
- Food Science & Technology (AREA)
- Medicinal Chemistry (AREA)
- Measurement Of Current Or Voltage (AREA)
- Measurement Of Resistance Or Impedance (AREA)
Abstract
The readiness for operation of a lambda measuring probe 10 is determined from the probe resistance which is a measure of probe temperature by applying a voltage U0 (5V) across the probe and resistors R1, R2 and comparing the voltage across the probe with a first threshold voltage (N2V), which is significantly greater than the probe output voltage. When the voltage across the probe becomes lower than the first threshold voltage, that threshold voltage is changed to a second threshold value (N3V) to detect a cold state being reattained. The applied voltage U0 is removed at intervals and the probe output compared with a third voltage (N 400mV) for rich/lean mixture measured. <IMAGE>
Description
Process and'Apparatus for testing a, Lambda Measuring Probe
This invention relates to a process of the type defined in the introductory part of Claim 1 and an apparatus for carrying Out this process.
It is an object of the present invention to to develop a process and an apparatus of the type mentioned above so that the temperature dependent readiness for operation of the lambda measuring probe and the mixture state measured by the probe can be reliably monitored by simple means and without elaborate circuit technology. These means should also enable the fundamental operability of the lambda measuring probe to be monitored.
To solve this problem, a process according to the introductory part of claim 1 is distinguished according to the invention by the features indicated in the characterising part of this claim. By a simple evaluation of the voltage drop across the lambda measuring probe and of its natural voltage and by a comparison with suitable preset voltage threshold values, the cold, hot, rich and lean states of the lambda measuring probe can be determined very simply and rapidly. By a hysteresis type of increase of the first voltage threshold value to the second voltage threshold value in the hot state, the safety gap protecting it against disturbances in operation can be considerably improved. The various voltage threshold values can be preset and controlled by simple means so that the above mentioned process is mainly concentrated only on evaluating a voltage in the series circuit.
The further development according to Claim 2 enables a relatively small supply measuring voltage of about 5 Volt to be used, which.must still be large compared with the approximately 800 milliVolt natural voltage of the ladbda measuring probe "The supply measuring voltage may therefore be obtained, for example, from the on boardvoltage supply already available in a motor vehicle.
The further development according to Claim 3 enables various measuring processes to be repeated in particular sequences so that a simple control operation can be carried out.
The further development according to Claim 4 provides a simplification in that -in the high temperature state, the otage dY:id1: measurements may be carried out at longer time intervals.
The digitalization carried out as a further development according to claim 5 enables the voltage to be very simply and reliably determined and processed.
The temporary storage of the measured states which takes place according to the further development provided in claim 6 enables any further processing to be carried out at any moment between two interrogation cycles.
The further developments according to Claims 7 and 8 enable an additional evaluation of the measured voltages to be carried out to determine the temperature state and states of the probe. This enables very versatile monitoring to be carried out by very simple means.
To solve the given problem, an apparatus according to the invention suitable for carrying out the process is distinguished by the features given in the characterising part of Claim 9. Said apparatus is composed of a small number of inexpensive, commercially available parts. It is very simple and clearly arranged and can be used for monitoring all the temperature and mixture states and operability of the lambda measuring probe simply by evaluating the voltage across the probe.
The further development according to Claim 10 enables the voltages measured to be evaluated in a very simple and reliable manner.
The further development according to Claim 11 provides a very simple means of switching over between a voltage dividing measurement and a measurement of the natural voltage of the measuring probeJ The further development according to claim 12 provides a simple means of compensating for the voltage drop across the coupling diode when the latter is switch. through so that this voltage drop will not interfere with the evaluation of the relatively small natural voltage of the lambda measuring probe.
The further development according to claims 13 and 14 provides for the suppression of short interfering impulses which could otherwise lead to false results', especially when evaluating the natural voltage of the probe.
The invention will now be described with reference to an exemplary embodiment illustrated in a drawing.
The drawing shows schematically a lambda measuring probe 10 having an internal resistance R. and a source of natural voltage UL. The internal resistance R. drops sharply with the temperature of the probe in known manner. The measuring probe is not ready for operation until an operating temperature of from 200 to 3000C is reached, when the internal resistance falls below about 100 Kilo-Ohm. A substantially higher internal resistance thus indicates that the lambda measuring probe 10 is in the cold or inoperative state. The natural voltage
UL of the lambda measuring probe depends on the mixture strength and amounts to about 400 milliVolts for a lambda value of-1. The natural voltage increases and decreases very steeply with decreasing and increasing lambda values.
At very small lambda values, the natural voltage rises to about 800 milliVolts.
As shown in the drawing, the lambda measuring probe 10 is connected in series with a comparator resistor Rl, which should also have a resistance of about 100
Kilo-Ohm, to a supply measuring voltage U0 which may be a direct voltage of, for example, about 5 Volt. Connected between the comparator resistor R1 and the lambda measuring probe 10 are'a compensatioA diode D1 and a resistor R2 of comparatively low resistance forming part of, a disturbance suppressing RC element with additional capacitor C.
A control instrument 12, preferably in the form of a microprocessor, is connected to a tap 18 of the series cirtuit by a coupling diode D2. The control instrument 12 may supply the coupling diode D2 with suitable potentials so that the diode is either blocked, in which case the series circuit is supplied with the supply measuring voltage U0, or switched through, in which case the tap 1 8 is approximately at earth potential except for the conducting state voltage of the coupling diode D2. The low voltage drop across the coupling diode D2 is compensated for by the compensation diode D1 so that the natural voltage
UL may be reliably determined by way of the tap 20.
An analogue/digital convertor 14 is connected in the present case to the tap 20 and the RC element with the members R2 and C to digitalize the voltage at the tap 20. A threshold element 16 is connected in series with the analogue/digital convertor 14. The parts 14 and 16 are controlled by the control instrument 12 and the results of voltage comparison are transmitted to the control instrument 12 at least by the threshold element 16. The voltage at the tap 20 may be transmitted direct from the analogue/digit,al convertor to the control instrument 12 after digitalization or it may by-pass the analogue/ digital convertor 14 to be transmitted direct to the threshold element 16, as indicated by the broken lines.
In the threshold element 16, the voltage at the tap 20 may be compared with various voltage threshold values preset by the control instrument 12. When the coupling diode D2 is shut off, the relatively large voltage drop at the tap "20 (about 2 to 3 Volt) is first compared with a smaller threshold value, say about 2 Volt. When the voltage drop has fallen below this threshold value in the course of the gradual'heating up of the lambda measuring probe 10,this first voltage threshold value is increased to a second threshold value, for example of about 3 Volt, for the next interrogation cycles of the voltage drop.
It is only when this greater, second threshold value is exceeded that the lambda measuring probe 10 io recognised as having again reached the cold state. This increase from the first to the second voltage threshold value provides for a high degree of freedom from disturbance in operation.
When the lambda measuring probe 10 is in the high temperature state, i.e. when the voltage drop at the.
tap 20 is less than the first voltage threshold value or at least less than the second voltage threshold value, repeated interrogation of the natural voltage UL of the lambda measuring probe 10 takes place between the repeated interrogation cycles of the voltage drop or temperature state of the lambda measuring probe 10 after the coupling diode D2 has been suitably switched through. This small natural voltage U is compared in the threshold element
L 16 with a third, correspondingly small voltage threshold value of about 400 milliVolts which, with a lambda value of about 1, represents the limit between the rich and the lean state of the lambda measuring probe 10.
The comparison results obtained by the threshold element 16 are transmitted to the control instrument 12 and from there they are transmitted as starting signals
A which represent the temperature and mixture states.
The natural voltage of the lambda measuring probe 10 need not be evaluated when the probe is in the cold state. Measurement and evaluation of the natural voltage may therefore be cancelled so long as the voltage dividing measurement indicates the cold state and need only set in when the lambda measuring probe 10 is found to be in the operational or hot state.
The voltage at the tap 20, which may either be a voltage drop indicated by the voltage dividing measurement or the natural voltage UL measured when the coupling diode
D2 is switched through, may be transmitted to the control instrument 12, either directly or after digitalization in the analogue/digital convertor 14, to enable a particular information concerning the temperature and operational states to be obtained. For'example, the voltage drop is a direct measure of the temperature state of the lambda measuring probe 10. On the other hand, certain conclusions concerning the operability of the lambda measuring probe 10 may-be drawn from the natural voltage UL measured.
If, for example, the natural voltage UL, is at most only about 600 milliVolt in the rich state, this is an indication of the ageing effect of the measuring probe.
The present invention thus enables the entire temperature and operational states of a lambda measuring probe to be' determined very rapidly and reliably with extremely simple means within virtually any time slot pattern.
This constant monitoring is very suitable for control and regulating procedures in motor vehicles, as in injection systems.
Claims (16)
1. Process fpr repeated testing of the readiness for operation of a lambda measuring probe and of the fuel mixture strength by means of this measuring probe by evaluating the voltage across the probe, wherein a) the measuring probe is repeatedly subjected to
a voltage dividing measurement with superimposed
supply measuring voltage to determine its temperature
state, the voltage drop across the measuring probe
being large, at least in the temperature range from
cold to readiness for operation, compared with the
natural voltage of the probe',which is dependent upon
the mixture and this voltage drop being evaluated
by b) comparing the voltage drop with a first voltage
threshold value, a voltage drop below this value
being recognised as a high temperature state of readi
ness for operation and c) increasing the first voltage threshold value to a
second voltage threshold value-when this high temper
ature state has been recognised until the second
threshold value is exceeded, which is a reliable
indication of a return to the cold state, and, d) by discontinuing the superimposition of the supply
measuring voltage between the voltage dividing measure
ments and evaluating the natural voltage of the measur
ing probe when the latter is in the high temperature
state by comparing it with ra smaller, third threshold
value which indicates the rich mixture state when
it is exceeded and indicates the lean state when
the natural voltage measured falls below the third
threshold value.
2. Process according to claim 1, wherein when the supply measuring voltage is about 5 Volt, the first and second voltage threshold values are about 2 to 3 Volts and the third voltage' threshold value is about 400 milliVolt.
3. Process according to claim 1 or claim 2, wherein
the voltage dividing measurements are carried out in a first time slot pattern and the mixture measurements in the hot temperature state are carried out between the aforesaid measurements in' a narrower, second time slot pattern synchronized. with the first.
4. Process according to one of the claims 1 to 3, wherein
the voltage dividing measurements are repeated at shorter intervals in the cold state than in the high temperature state.
5. Process according to one of the claims 1 to 4, wherein
the voltage drop and the natural voltage are digitalized and then processed.
6. Process according to one of the claims 1 to 5,wherein
the temperature state and mixture state determined on each occasion are stored until the next interrogation cycle.
7. Process according to one of the claims 1 to 6,wherein
the magnitude of the voltage drop measured across the measuring probe is evaluated as a measure of the temperature of the probe.
8. Process according to one of the claims 1 to 7, wherein
the magnitude of the natural voltage measured across the measuring probe is evaluated as a measure ofsthe fundamental functional efficiency, such as its ageing.
9. Apparatus for carrying out the process according to one or more of the claims 1 to 8, comprising a series circuit of a comparator resistor and lambda measuring probe ,which circuit can be connected to a source of supply voltage and a switching devi > * for selectively switching on and shutting off the supply measuring voltage; a threshold element connected to the lambda measuring probe and a control instrument for repeatedly controlling the switching on and shutting off of the supply measuring voltage, and presetting of suitable voltage threshold values in the threshold element and the output of the temperature and/or mixture states.
10. Apparatus according to claim 9; further comprising an analogue/digital convertor between the measuring probe and the threshold element.
11. Apparatus according to claim 9 or 10-, wherein the control instrument is a microprocessor which is connected by its output7 which can be switched between two states6 to the series circuit by way of a coupling diode so that the supply measuring voltage is either supplied to the measuring probe or shut off therefrom according to the switching state of the microprocessor.
12. Apparatus according to one of the claims 9 to 117 wherein a compensation diode is connected into the series circuit between the comparator resistor and the measuring probe; which compensation diode serves as voltage compensator for the voltage drip which takes place across the coupling diode when the supply measuring voltage is shut off.
13. Apparatus according to one of the claims 9 to 12, wherein an RC element is connected to the input of the analogue/digital convertor for suppressing disturbances.
14. Apparatus according to claim 137 wherein a resistor of the RC element is arranged in the series circuit between the compensation diode and the measuring probe.
15. A process for repeated testing of readiness of a lambda measuring probe substantially as herein described with reference to the accompanying drawing.
16. An apparatus for repeated testing of the readiness of a lambda measuring probe substantially as herein described and as illustrated in the accompanying drawing.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19873705823 DE3705823A1 (en) | 1987-02-24 | 1987-02-24 | METHOD AND DEVICE FOR CHECKING A LAMBDA MEASURING PROBE |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8803821D0 GB8803821D0 (en) | 1988-03-16 |
| GB2201516A true GB2201516A (en) | 1988-09-01 |
| GB2201516B GB2201516B (en) | 1990-10-31 |
Family
ID=6321617
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8803821A Expired - Fee Related GB2201516B (en) | 1987-02-24 | 1988-02-18 | Process and apparatus for testing a lambda measuring probe |
Country Status (4)
| Country | Link |
|---|---|
| DE (1) | DE3705823A1 (en) |
| FR (1) | FR2611273A1 (en) |
| GB (1) | GB2201516B (en) |
| IT (1) | IT1219463B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2245711B (en) * | 1990-06-11 | 1995-01-11 | Matsushita Electric Works Ltd | Electrochemical gas sensor |
| FR2752057A1 (en) * | 1996-08-02 | 1998-02-06 | Bosch Gmbh Robert | METHOD AND DEVICE FOR DETERMINING THE SENSITIVITY OF A HYDROCARBON DETECTOR FOR AN INTERNAL COMBUSTION ENGINE |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4115690A1 (en) * | 1991-05-14 | 1992-11-19 | Moebius Hans Heinrich Prof Dr | Determining selected time points during regular changes of oxygen@ concn. contained in liquid flowing in vessel - using galvanic cell, with two electrodes with partition in-between, on oxide ion conducting solid body without or with heating |
| US5582793A (en) * | 1991-10-03 | 1996-12-10 | Antaeus Group, Inc. | Process for treating waste material |
| DE4402618C2 (en) * | 1994-01-28 | 1998-04-30 | Uwe Bastian | Method and measuring arrangement for checking the lambda control loop in the case of regulated exhaust gas catalysts |
| DE19508560A1 (en) * | 1995-03-10 | 1996-09-12 | Bosch Gmbh Robert | Prepn. circuit for signals from probe in combustion engine exhaust pipe |
| DE102004018289A1 (en) * | 2004-04-15 | 2005-11-03 | Abb Patent Gmbh | Method for determining the response and sensitivity of an oxygen sensor in a metering device |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1577048A (en) * | 1976-03-26 | 1980-10-15 | Bosch Gmbh Robert | Methods and apparatusfor switching-on and/or switching-off a regulating device operating with a sensor |
| GB1586633A (en) * | 1977-01-08 | 1981-03-25 | Bosch Gmbh Robert | Device for detecting the regulating readiness of a probe |
| GB1594247A (en) * | 1976-12-28 | 1981-07-30 | Nissan Motor | Exhaust gas sensor temperature detection system |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4178793A (en) * | 1978-09-05 | 1979-12-18 | General Motors Corporation | Apparatus for oxygen sensor impedance measurement |
| DE3024607A1 (en) * | 1980-06-28 | 1982-02-04 | Robert Bosch Gmbh, 7000 Stuttgart | DEVICE FOR REGULATING THE FUEL / AIR RATIO IN INTERNAL COMBUSTION ENGINES |
| JPS5934439A (en) * | 1982-08-19 | 1984-02-24 | Honda Motor Co Ltd | Air-fuel feedback control method |
-
1987
- 1987-02-24 DE DE19873705823 patent/DE3705823A1/en not_active Withdrawn
-
1988
- 1988-02-18 GB GB8803821A patent/GB2201516B/en not_active Expired - Fee Related
- 1988-02-23 FR FR8802151A patent/FR2611273A1/en active Pending
- 1988-02-23 IT IT47660/88A patent/IT1219463B/en active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1577048A (en) * | 1976-03-26 | 1980-10-15 | Bosch Gmbh Robert | Methods and apparatusfor switching-on and/or switching-off a regulating device operating with a sensor |
| GB1594247A (en) * | 1976-12-28 | 1981-07-30 | Nissan Motor | Exhaust gas sensor temperature detection system |
| GB1586633A (en) * | 1977-01-08 | 1981-03-25 | Bosch Gmbh Robert | Device for detecting the regulating readiness of a probe |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2245711B (en) * | 1990-06-11 | 1995-01-11 | Matsushita Electric Works Ltd | Electrochemical gas sensor |
| FR2752057A1 (en) * | 1996-08-02 | 1998-02-06 | Bosch Gmbh Robert | METHOD AND DEVICE FOR DETERMINING THE SENSITIVITY OF A HYDROCARBON DETECTOR FOR AN INTERNAL COMBUSTION ENGINE |
| US5875768A (en) * | 1996-08-02 | 1999-03-02 | Robert Bosch Gmbh | Method and arrangement for determining the sensitivity of a hydrocarbon sensor for an internal combustion engine |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2201516B (en) | 1990-10-31 |
| DE3705823A1 (en) | 1988-09-01 |
| IT8847660A0 (en) | 1988-02-23 |
| IT1219463B (en) | 1990-05-18 |
| FR2611273A1 (en) | 1988-08-26 |
| GB8803821D0 (en) | 1988-03-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19940218 |