Produkt / Product:	Planar Wide Band Lambda Sensor
Typ / Type:	LSU 4.2
Bestellnummer / Part Number:	0 258 007 ...
Angebotszeichnung / Offer Drawing:	A 258 400 ...

Gültig ab / Valid from:	21.3.2001

Bemerkung / Comment:

Nr.	Seite	Änderung	Datum	K3/ESV6-Ham	K3/ESV	K3-
Index	Page	Revision	Date			sales
-	-	Erstausgabe / First Edition	26.5.97
1.1	3	Trim resistance range added
1.3	3	Iso. measurement conditions
1.4	4	Heater supply spec. extended
1.5	4	Heater supply frequency added
2.7	6	Pumping current limits added
4	8,9	Change of characteristic line
		and target Ri=80
5.10	13	FV test for LSU4.2 added
5.12	13	Gas leakage test pressure inc.
5.13	13	Drop test added
7.1	15	Assessment of field sensors
8	17	Variation LSU4.2 added
		Variation d2 added
9.9	19	Sensor boss Spec. extended
9.16	20	Note for water dripping added
10.7	22	Note for interpret. AWS/CJ110	25.1.99
2.3/4	5	Temperature spec. extended
4	8-10	Characteristics extended
7.1	16	Characteristics aged changed
8	18	Variation “d4” prot. tube
		Variation short PTFE tube
		Variation “Inconel tube” deleted
		Variation LSU4.7 deleted
9.9	20	Sensor boss spec. extended	6.10.00
5.12	15	Gas leak test reworked
4.1	8	characteristics for “d4” variant	21.3.01	gez Hamann	gez
					Neumann
				gez Meier

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	Contents
1.	Characteristics	3
2.	Application conditions	5
3.	Test methods	7
4.	Functional values	8
5.	Environmental test specification	11
6.	Production monitoring tests	15
7.	Assessment of aged sensors	16
8.	Design variations	18
9.	Installation instructions	19
10.	Operating instructions	22

Reference Specifications
Application guideline	KGS_LS (APP 108)
Handling instruction	Y 258 E00 000
Temperature measurement sensors	Y 258	E00	001
Test method: measurement temperature and	Y 258	E00	003
thermoshock
Measurement in synthetic gas (PSG)	Y 258	E00	004
LSU test bench and test method	Y 258	E00	005

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For design variations different values are marked.

For explanation of variations see section 8.

General

The wide band lambda sensor LSU is a planar ZrO2 dual cell limiting current sensor with an integrated heater. It is used to measure the oxygen contents

and the -value of engine exhaust gases. Its monotonic output signal in the range of =0.7 to air makes the LSU capable of being used as an universal sensor for =1 measurement as well as for other ranges.

The connector module contains a trimming resistor, which defines the characteristics of the sensor and is necessary for the sensor function.

The wide band sensor LSU operates only in combination with a special control unit.

1.	Characteristics
1.1	Electrical connection:		6 pole
	Range of trim resistor		30 ... 300
1.2	Heater supply
	The heater supply voltage must	be controlled, so that the temperature of
	the sensor is kept at a nominal temperature of approx. 750°C.
	Nominal voltage, test voltage:		9 V
	Nominal heater power at 9 V heater supply
	at thermal equilibrium (exhaust gas
	temperature 350°C, exhaust gas	flow
	rate approx. 0.7 m/s):		approx. 10 Watt
	Nominal heater cold resistance	at 20°C
	ambient temperature for new sensor,
	including cable and connector:		3.2
	Minimum heater cold resistance	at -40°C:	2.1

1.3Isolation resistance

between housing and each heater- and

sensor circuit connector pin under normal

conditions (23°C/50% humidity) with heater off: = 30 M

between sensor circuit and housing
at 530°C hexagon temperature, new	and
after 500 h aging acc. to section	5.1:	= 100 k

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1.4When the heater is switched on, heater power must be limited as follows:

-the initial value of heater voltage during the heat-up phase is dependent on the temperature of the sensor at start.

For “fast light off” all conditions acc. to Y 258 E00 003 sec. 1.4.2 must be fulfilled, (e.g. sensor position close to engine, rapid heat up of ex- haust gas).

TSensor / °C		-40	-10	20	50
VH,eff,max (t=0)/V	(standard)	7.4	7.8	8.2	8.6
	(fast light off)	9.0	9.5	10.0	10.5

-	ramp rate	VH,eff	/ t	= 0,4 V/s
effective heater voltage			short time max. permissible eff. heater voltage
VHeff / V			(heat up phase; load change):	VHeff max = 13 V for t = 200h
	13 V		//	max. eff. heater voltage
				continuous: VHeff = 12 V
			maximum
			ramp rate
			= 0,4V/s
			application specific
		max. initial value
		acc. to table
	0		application specific		time after start

Maximum permissible heat up rate with limited heater power to reduce the thermal stresses in the heat-up phase

1.5 Maximum	permissible effective heater voltage VH,eff
at Tceramic < 900°C
- short	time = 200h:			= 13 V
- continuous:				=	12 V
Minimum	frequency of heater voltage control
- at supply voltage Vbatt		(peak) =	16V:	=	2 Hz

Note: the use of the sensor with 24V power systems is not recommended.

Note: duty cycle = (VH,eff / Vbatt)2

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2.Application conditions

For all temperature measurements refer to section 3: test methods.

2.1	Temperature range, passive:	-40°C ... +100°C
	(storage temperature)
2.2	Operating temperatures
	Exhaust gas at sensor element:	=	930°C
	Hexagon of the sensor housing:	=	570°C
	Cable grommet (PTFE formed hose)
	- sensor side:	=	250°C
	- cable side (upperhose crimp):	=	200°C
	Cable and protective sleeve:	=	250°C
	Connector:	=	120°C

2.3 Maximum temperatures (max. 250 h accumulated over lifetime)

Exhaust	gas at	sensor	element:	=	1030°C
Hexagon	of the	sensor	housing:	=	630°C

2.4 Maximum temperatures (max. 40 h accumulated over lifetime)

Cable grommet (PTFE formed hose)

-	sensor side:	=	280°C
-	cable side (upperhose crimp):	=	230°C
Cable and protective sleeve:		=	280°C

Notes:

If the exhaust gas temperature of 850°C is exceeded, the heater power must be switched off. In this case the accuracy of the sensor signal is limited.

If the max. gas temperature exceeds 850°C or hexagon temperature exceeds 500°C, the use of a longer thread boss is recommended (see section 9.9).

If the operating temperature is exceeded (within the max. temperature limits) for more then 10 minutes without break, the sensor function might be affected during this time.

2.5 Temperature of sensor ceramic element with

condensation	water present at exhaust	side:	=	350°C
Note: sensor	is not ready to control	at
a sensor temperature of 350°C

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2.6Permissible vibrations

(measured at the sensor housing)

Stochastic	vibrations:	=	1000 m/s2
(peak level)
Sinusoidal	vibrations
- vibration displacement:		=	0.3 mm
- vibration acceleration:		=	300 m/s2
2.7 Max. current load of =1 Nernst-cell		=
Continuous	DC:		10	µA
Continuous	AC (f = 1...4 kHz)	=	250 µA
for RI measurement
Max. pumping current into pump cell
- for rich	gas signal	=	-9	mA
- for lean	gas signal	=	18	mA

2.8Permissible fuel additives

In accordance with DIN EN228 for commercially available unleaded fuel.

For use of leaded fuel see section 7.2

2.9Oil consumption and oil brand

Permissible figures and data must be determined by the customer by the way of adequate large-scale tests.

	Guide value:	= 0.7 l/1000 km
2.10	Silicon resistance	ref. to test 5.11

2.11Lifetime

The technical development of the sensor is aligned to a service life of 160.000 km and a maximum life time of 10 years. Failure criterion is the non-compliance with the measurement data as mentioned under section 7.

The following conditions must be fulfilled in order to reach this service life:

-Application conditions acc. to section 1 and 2.

-Installation conditions acc. to section 9.

-Checking of each application/installation location according to applica- tion guideline KGS_LS

-Usage of a RB approved sensor connector with single chamber sealing and gold plated sensor signal contacts.

The commercial warranty and liability is regulated in the conditions of delivery, independent of the above figures.

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3. Test methods

3.1Temperature measurement

Temperature measurements are performed with a special sensor equipped with NiCrNi thermoelements, see sketch. Sensor Type "MM" has measurement points

at the upper side of the PTFE formed hose (Tupperhose), the cable grommet (Tgrommet) and at the hexagon of the sensor housing (Thexagon). The sensor type "MXT" has an additional measurement point for the exhaust gas temperature

(Texhaust).

For more information see description of temperature measurement sensors Y 258 E00 001 and description of measuring method Y 258 E00 003.

Texhaust

Tgrommet	Tupperhose
Thexagon

3.2Test benches and test methods for measuring the functional values as in section 4:

Synthetic test	gas	test	bench (PSG)	Y	258	E00	004
LSU test bench	and	test	method	Y	258	E00	005

Special hints for carrying out test bench measurements:

Due to the limited measurement device capability of the gas test benches cpk calculations with the specified tolerances are not useful.

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4.Functional values

The measurement is done with the sensor operated with a AWS control unit. The given tolerances are only for the lambda sensor LSU4. The heater power

is closed-loop controlled while the measurement is done, so that a nominal sensor internal resistance of RIN=80 (measured with 1...4 kHz) is reached, this corresponds to a sensor ceramic temperature of approx. 750°C in new state.

4.1Measurement at = 1 in synthetic gas test bench at 350° gas temperature acc. to test method Y 258 E00 004:

			New		After 500h			After 2000h
Sensors with					test bench run			test bench run
protection tube “d1”,					see 5.1			see 5.1
see sec. 8
static		1.009	±	0.006	1.009	±	0.007	1.009	±	0.008
(pump current IP=0)
dynamic		1.010	±	0.006	1.010	±	0.007	1.010	±	0.008
Frequency	[Hz]	2.8	±	0.8	2.8	±	1.0	2.6	±	1.0
Sensors with			New		after 500h			after 2000h
protection tube “d2”
static		1.009	±	0.006	1.009	±	0.007	1.009	±	0.008
(pump current IP=0)
dynamic		1.010	±	0.006	1.010	±	0.007	1.010	±	0.008
Frequency	[Hz]	2.3	±	0.8	2.3	±	1.0	2.1	±	1.0
Sensors with			New		after 500h			after 2000h
protection tube “d4”
static		1.010	±	0.006	1.010	±	0.007	1,010	±	0,008
(pump current IP=0)
dynamic		1.010	±	0.006	1.010	±	0.007	1,010	±	0,008
Frequency	[Hz]	2.8	±	0.8	2.8	±	1.0	2,6	±	1,0

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4.2Measurement of rich and lean characteristic in LSU test bench at 20° gas temperature acc. to test method Y 258 E00 005:

	New	After 500h	After 2000h
		test bench run	test bench run
		see 5.1	see 5.1
Measurement gas for =1.7:
8.29% O2 in N2 at p=1013 hPa
signal at =1.7: (*)	1,70 ± 0,05	1,70 ± 0,10	1,70 ± 0,15
Measurement gas for =0.8:
3.15% H2, 3.15% CO2, 4.05% CO
in N2 at p=1013 hPa
signal at =0.8:	0.80 ± 0.01	0.80 ± 0.02	0.80 ± 0.04

(*) For other values and operating conditions the tolerances can be calculated.

For	the range of >1:	= ( -1) IP/IP
For	a H/C-ratio of H/C=2:	= (xO2/3 +1) / (1-4.76*xO2)

4.3Measurement of the light-off time of the sensor in synthetic gas test bench at 20° gas temperature acc. to test method Y 258 E00 004:

			New	After 500h	After	2000h
				test bench run	test bench run
				see 5.1	see	5.1
Light-off time	[s]	=	20	= 20	= 20

Note: in the engine the light-off time might be shorter, depending on installation and gas temperature conditions.

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4.4Nominal characteristic line

Characteristic current through measuring resistance 61.9 , pgas=1013hPa,

internal resistance of =1 Nernst cell RIN = 80 (AC 1...4 kHz)
IP meas / mA
3,000
2,500
2,000
1,500
												gas: O 2 in N 2
1,000
0,500
0,000
	0		5				10			15				20			25
-0,500											O2-concentration				xO2 / %
							O2-conc. xO2/%				0,0		3,0	6,0	8,29		12,0	20,9
							Ip,meas		/ mA		0,00		0,34	0,68	0,95		1,40	2,55
IP meas / mA
1,500
1,000
0,500												lean gas: O 2 in N2
											= (xO2 / 3 +1) / (1-4.76*xO2 )					for H/C=2
0,000
0,70	0,80	0,90	1,00 1,1	1,20	1,30	1,40	1,50	1,60	1,70 1,80		1,90	2,00 2,10		2,20	2,30	2,40 2,50
-0,500
-1,000								rich gas mixture of synthetic gas
								9%CO, 7%H2, 7%CO2				in N2
-1,500
-2,000
			-value		0,70		0,80	0,85		0,90	1,009		1,18	1,43	1,70		2,42	207
			Ip,meas/mA		-1,85	-1,08		-0,76		-0,47	0,00		0,34	0,68	0,95		1,40	2,55

Note: these characteristics are valid for the specified test gas only. They may be different for real engine exhaust gas and must be determined separately.

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5.Environmental test specification

Each test must be carried out with new sensors. If not otherwise specified, after the tests the sensors must fulfill the functional values of new sen- sors as in section 4. The tests are carried out with an applied heater voltage of 9V, if not otherwise specified.

5.1Engine endurance run

For measurements of functional values after endurance test the sensors have to be fitted into the exhaust system of a =1 controlled gasoline engine. The sensors are operated with a LSU control unit in this test (closed loop control of heater power).

Speed and load are changed in a 6-cycle program so that a temperature curve is reached in the sensor tip as per sketch.

-Fuel: according to DIN EN228 for commercially available unleaded fuel.

-Oil consumption = 0,04 l/h.

-Oil brand: multi-range oil viscosity 10W-40, API specification SF. Compliance with the temperature limits as per section 2 must be ensured by adequate cooling. After the test the functional values for aged sensors in section 4 must be fulfilled.

The exhaust gas temperature is set by varying engine speed and load. The temperature at the hexagon is limited by additional air cooling.

T1 = exhaust gas

T2 = housing hexagon

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5.2 Sinusoidal vibration test acc to IEC 68-2-6 test Fc

Test equipment: electrodynamic vibrator

Test between	50...150	Hz at constant amplitude ± 0,3 mm and between
	150...500	Hz at constant acceleration of ± 300 m/s2.
Frequency change velocity:			1	octave/min.
Test duration:			8	h to be performed in all 3
			perpendicular planes.
Ambient temperature:			25 ± 3 °C.

Sensor mounting see sketch. In order to provide a defined wire sag, the cable end is at first pre-tensioned with 5 N and then moved 10 mm towards the sensor and fixed in position A.

Sensor mounting for vibration test

0
1		4
	A
22		6
		2
		8
		45
		°
	7
	3
		168
	122
30
30
		20
201
290

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5.3	Random vibration test
	Test equipment:	Random vibration test bench
		as per Bosch standard N42 AP 411.
	Acceleration:	1000	m/s2 (peak level)
	Test duration:	24 h
	Sensor mounting:	same	as 5.2
	Ambient temperature:	25 ±	3°C

5.4Test with damp heat, cyclic (12+12-hour cycle) acc. to IEC 68-2-30, test Db

No. of cycles:	21
max. air temperature:	40°C

The heater has to be switched off during this test.

5.5 Salt mist test acc. to IEC 68-2-11, test Ka

Testing time:

288 h

The sensor heating is switched on 5 minutes before and during testing. In order to prevent water from reaching the exhaust side sensor ceramic a stainless steel sleeve is screwed onto the sensor thread for proper seal- ing.

5.6 Change of temperature acc. to IEC 68-2-14, test Na

Minimum temperature:	-40	°C
Maximum temperature:	130	°C
Exposure duration at each temp.:	30 min.
No. of temperature cycles:	250

The heater has to be switched off during this test.

5.7Sulfur dioxide test with general condensation of moisture acc. to DIN EN ISO 6988

No. of cycles:

6 (24 h for each cycle)

The heater has to be switched off during this test.

In order to protect the exhaust side sensor ceramic a stainless steel sleeve is screwed onto the sensor thread for proper sealing.

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5.8Submergence test acc. IEC 529, IPx7

Water level 150 mm above sensor cable outlet. Test duration is 30 min. The connection system must be out of the water during the test. The sensor is operated with a LSU control unit in this test, the sensor signal is moni- tored. In the test time the signal must be stable.

5.9Wire pull test

The mounted sensor has to withstand an axial force of 100 N applied to the connector for 1 min.

5.10Fuel vapor test

The exhaust gas side of the sensor is exposed to fuel vapor of 43°C in a

test chamber. The soak time is 2 h. After this the sensor is removed and then heated with 9V. The =1-cell signal of the sensor in ambient air is

monitored for the time tmeas. A failure is defined as a decrease of the lean output voltage of the =1 cell below -100 mV.

tmeas: 120 min

5.11Silicon resistance test

Engine test run with additional silicon content in fuel.

The sensors are fitted in the exhaust pipe of a =1 controlled engine as in 5.1 (with LSU control unit), but operated under the following conditions:

exhaust		gas temperature	:	400°C
test	time		:	6 h
Silicon		content in fuel	:	0.12cm3/l Oktamethylcyclotetrasiloxane
fuel	consumption over the test time :			18 l

Test evaluation: after the test static (see section 4) must be within the range of 1.000 ... 1.022

5.12Fine leak test

The gas leakage is measured from exhaust gas side with an air pressure of 4 bar. The leakage rate must be smaller than 0.1 ml/min.

5.13Drop test acc. to IEC 68-2-32 test Ed proc. 1

The sensor is dropped to a concrete floor from a height of 1m for one time.

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6.Production monitoring tests

For monitoring production quality the following tests are carried out on a regular basis:

500 h engine endurance run as in 5.1 (audit test)

Submergence test equivalent to 5.8 (audit test)

Wire pull test as in 5.9 (audit test)

Sensor characteristics as in section 4 (lot release test)

Sensor function test

-calibration of sensor characteristic in synthetic lean gas

-functional test in synthetic rich gas

(100% test)

Fine leak test as in 5.12 (audit test)

Isolation resistance between heater, sensor signal circuit and housing under normal conditions acc. to 1.3

(100% test)

Isolation resistance between sensor signal circuit and housing under hot conditions acc. to 1.3

(audit test)

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7. Assessment of aged sensors

7.1Sensors from general endurance runs and from field operation

The measurement is done with measurement conditions as in section 4.

Measurement of rich and lean characteristic in LSU test bench at 20° gas temperature acc. to test method Y 258 E00 005:

Measurement gas for =1.7:
8.29% O2 in N2 at p=1013 hPa
signal at =1.7: (*)	1,70 ± 0,15
Measurement gas for =0.8:
3.15% H2, 3.15% CO2, 4.05% CO
in N2 at p=1013 hPa
signal at =0.8:	0.80 ± 0.04

If these figures are complied with, it can be expected that the sensor will be capable of closed loop control under normal operation conditions. How- ever since a vehicle's exhaust gas emission values also depend to a great extent upon other components in the system (engine, catalytic converter, mounting position, closed-loop control circuit), these figures cannot be taken as a reliable indication of emissions behavior in an emission test.

7.2 Sensors Used with leaded fuel

Depending on the lead contents of the used fuel the expected service life time is: (preliminary data)

- for 0.6			g Pb/l:		20 000	km
-	for	0.4	g	Pb/l:	30 000	km
-	for	0.15 g		Pb/l:	60 000	km

In general, when using leaded fuel the sensor will be replaced, when functional problems occur, e.g. unstable idle speed, driveability problems.

The system diagnose functions should be rechecked for the reduced demands on the sensor and the increased response times when leaded fuel is used.

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7.3General function test

The following tests can be done as a rough check of the sensor function (operation with control unit):

Plausibility check in rich exhaust gas: - sensor signal: rich

Plausibility check on air: - sensor signal: air signal

Heater cold resistance at room temperature:

- resistance measurement with multimeter between grey and white cable, sensor not connected to control unit, connector pinout see offer drawing:

RH,cold = 2,5 ... < 10

Visual inspection for mechanical damage

If a failure is seen in the above tests, the sensor should be installed in another test bench or vehicle and tested again. Goal: Exclude a failure of the wire harness or the control unit resp. the ECU.

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8.Design variations

The following variations are available:

8.1Protection tubes

Sensor with protection tube type “d1” with big holes. Sensor with protection tube type “d2” with smaller holes. Sensor with protection tube type “d4” with smaller holes.

Sensors with d2 and d4 tube can be applied in cases of high particulate concentration in the exhaust gas. The d2 protection tube gives also a par- tial improvement regarding the resistance against condensation water in the exhaust gas at engine start (thermoshock).

8.2PTFE formed hose

Longer PTFE hose at cable grommet for installation with critical tempera- ture conditions in the sensor area.

Shortened PTFE hose at cable grommet.

Note: the temperature resistance is the same for both types at the defined measuring points.

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9.Installation instructions

In general, the sensor installation point must be tested sufficiently by the customer for function and durability in the respective application.

9.1Installation in the exhaust system must be at a point guaranteeing repre- sentative exhaust gas composition whilst also satisfying the specified tem- perature limits.

9.2The heater power must always be switched on power controlled (e.g. duty cycled heater power), starting with a maximum ramp-up duty cycle as shown in the diagram in section 1.4. This is necessary to reduce thermal stress of the sensor element at cold start due to high peak power in the first seconds.

9.3The active sensor ceramic element is heated up quickly when the heater power is switched on. This means that the sensor installation location must be selected to minimize exhaust side stressing of the sensor ceramic ele- ment with condensation water in order to prevent ceramic element cracking.

Design measures:

-Locate sensor as close to the engine as possible, respecting max. allowed temperature range

-Attempt to achieve rapid heating-up of the exhaust pipes in the area in front of the sensor.

-The exhaust pipe in front of the sensor should not contain any pockets, projections, protrusions, edges, flex-tubes etc. to avoid accumulation of condensation water. A downwards slope of the pipe is recommended.

-Make sure, that the front hole of the double protection tube does not point against exhaust gas stream.

System measures:

-Never switch on sensor heating resp. control unit before engine start.

-Delay of sensor heater start or power control of the sensor heater (see diagram in 1.4) as a function of engine and ambient temperature.

For more information see test method Y 258 E00 003.

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9.4Installation angle should be inclined at least 10° towards horizontal (electrical connection upwards). Thus preventing the collection of liquids between sensor housing and sensor element during the cold start phase.

Other installation angles must be inspected and tested individually.

9.5Avoid excessive heating up of sensor cable grommet, particularly when the engine has been switched off after running under max. load conditions.

9.6The use of cleaning/greasing fluids or evaporating solids at the sensor plug connection is not permitted.

9.7Assembly with special high temperature resistant grease on the screw-in thread (e.g. Bosch-No. 5 964 080 112 for the 120g tin).

9.8Tightening torque: 40-60 Nm, material characteristics and strength of the thread must be appropriate.

9.10The sensor must be covered when underbody sealant (wax, tar etc.) or spray oil is applied to the vehicle.

9.11The influence of contamination which enters the exhaust gas through the

intake air or as a result of fuel, oil, sealing materials etc., and thus reaches the -sensor, is application specific and must be determined by customer tests.

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9.12The sensor must not be exposed to strong mechanical shocks (e.g. while the sensor is installed). Otherwise the sensor element may crack without visi- ble damage to the sensor housing.

9.13For physical reasons the sensor needs ambient air at its reference gas side. Replacement of the air volume inside the sensor must be guaranteed by a sufficient air permeability of the wires and the connectors between sen- sor and ECU. The breathability should be higher than 1 ml/minute at a test pressure of 100mbar.

The current Bosch LSU connector is available with an integrated pressure compensation hole with a permeable membrane, which guarantees a sufficient air supply. This hole must be saved from deterioration as wax, oil etc.

9.14Underfloor installation of the sensor at a distance from the engine re- quires an additional check of the following points:

-positioning of the sensor with respect to stone impact hazard

-positioning and fixing of cable and connector with respect to mechanical damage, cable bending stress and thermal stress.

9.15The PTFE formed hose is part of the reference air volume of the sensor and must be kept sealed and undamaged. For installation, the minimum bending radius of the hose must be 20mm (for long PTFE hose) resp. 12mm (for short hose). Keep the PTFE formed hose away from sharp edges and avoid con- tact/friction with frame/engine assembly.

The first fixing point for the cable to the car body should be 200mm to 400mm after the end of the PTFE formed hose, depending on movement of the exhaust system.

9.16The sensor should not be exposed to continuous, one-sided dripping of water, e.g. by the air conditioning condensation water outlet. The thermal stress could lead to mechanical damage of the sensor.

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10. Operating instructions

10.1Conditions for connection and electrical operation of the sensor

It must be assured, that when the sensor is operated, the connection to the control unit is save and not disconnected during operation, or that the control unit diagnosis recognizes a failing connection.

It is also not allowed, to disconnect or to connect the sensor to the control unit or ECU while the sensor or control unit is being operated.

Background: if the signal of the =1 cell is missing (e.g. connection failure), the internal control circuit can not operate correctly, so that

a)an excessive pumping voltage with wrong polarization can destroy the pumping cell of the sensor

b)the sensor element can be destroyed by overheating, when the closed loop heater control is not able to measure the ceramic temperature

The control unit may only be switched on after the sensor is connected completely.

The sensor cables may never be connected in the wrong way or wrong polar- ity, otherwise the sensor might be destroyed.

10.2Use without control unit

The sensor might stay in the exhaust gas stream for a short time also if the control unit is not connected. Connect and disconnect only, when the control unit is switched off.

10.3Use of LSU outside of the exhaust gas system

The sensor can also be used outside an exhaust gas system, e.g. on air.

When used in a stochiometric or rich gas ( = 1), e.g. measurement gas in

the test bench, it must be assured, that enough O2 donators are available in the gas to allow the pumping cell to work. Otherwise the ZrO2 ceramic of the sensor can be reduced and the sensor destroyed.

The O2 donator may be free oxygen (non-equilibrium measurement gas), H2O or CO2.

Guide values:	H2O:	=	2	vol	%
	CO2:	=	2	vol	%

10.4Electrical heating of the sensor

The sensor heater may never be connected directly to battery voltage, it must always be controlled by the LSU control unit or the vehicle ECU. Heat- ing the sensor before the engine is started is not allowed, see also sec- tion 9.3.

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10.5Sensor characteristic at low or high exhaust gas temperatures

Cold exhaust gas in addition to high gas velocity can lead to a reduced sensor ceramic temperature, when the heater control is not able to keep the constant ceramic temperature. This leads to a deviation of the sensor out- put signal.

Hot exhaust gas with a temperature above the operation temperature of the ceramic also leads to a deviation of the ceramic temperature and the sensor output signal.

Guide value: a temperature change of the sensor ceramic gives a deviation of the sensor output signal IP/IP of approx. 6%..7% / 100K.

10.6Pressure dependency of the sensor signal

A pressure change of the measured gas gives a deviation of the sensor output signal of:

IP(p) = Ip(p0) * p/(k+p) * (k+p0)/p0

The factor k is depending on operation conditions “rich” or “lean” and is for the measuring gas from LSU test bench in section 4.2:

klean gas = 0.47 bar krich gas = 0.39 bar

20,0%
15,0%
Ip/Ip(1013 hPa)
10,0%
5,0%
0,0%
							lambda > 1
-5,0%							k=0,47bar
-10,0%							lambda < 1
							k=0,39bar
-15,0%
0,6	0,8	1,0	1,2	1,4	1,6	1,8	2,0	2,2
			absolute pressure
			Absolut-Druck in [bar]

10.7Note for calculation of the sensor signal IP when using a control unit AWS or CJ110:

Output voltage AWS : VAWS [V] = 2.5 + 1.648 * IP,meas [mA] Output voltage CJ110 : VCJ110 [V] = 1.5 + 1.053 * IP,meas [mA]

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