TDC-Sensor 428

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The contents of this document may not be reproduced in any form or communicated to any thirdparty without the prior written consent of AVL

While every effort is made to ensure is correctness, AVL assumes no responsibility for errors oromissions which may occur in this document

This manual contains important warning and safety instructions to be

observed by the user This product is only intended for one certain area of application which is described in the instructions Furthermore the most important necessary prerequisites for application and operation as well as the safety measures are explained to ensure smooth operation.No warranty

or liability will be granted if the product is applied in areas others than those described or if the necessary prerequisites and safety measures are not met.

The product is to be operated and used only by qualified personnel capable

of observing the required safety measures.

Only accessories and supplies either delivered by AVL or approved by AVL are to be used with the product.

Due to the operating principle of this product the accuracy of measurement results which it produces do not only depend upon its correct operation and function, but also upon a variety of boundary conditions beyond the control

of the manufacturer Therefore the results obtained from this product must

be subjected to careful examination by an expert (e.g for plausibility) before action based upon the results is undertaken.

Adjustment and maintenance of instruments when open and under voltage are only to be carried out by a professional technician being aware of the dangers involved Protect instruments powered by the mains from humidity.

Repairs on the product are to be carried out by the manufacturer or qualified service personnel only.

Upon application of the product an expert is to ensure that neither the object

of examination nor the testing equipment are operated under conditions that

my lead to damage or injury.

List GmbH

Any connected equipment that uses higher voltages than 50 V AC or

75 V DC must satisfy the requirements of the 73/23/EEC Directive.

Only shielded cables may be used with appropriately shielded connectors

in order comply with the 89/336/EEC Electromagnetic Compatibility Directive.

Mains connections with standardised connectors and the exceptions mentioned do not need to be shielded.

This device must not be used in any environment where there is a danger

of explosion.

The device must not be exposed to rain or permanent humidity or moisture.

The device may only be opened by qualified personnel.

If a foreign body or liquid gets inside the device, disconnect it from the mains and have an expert check it before using it again.

Make sure that the device is supplied with the correct supply voltage.

TDC-Sensor Content

1.1 General 1

1.2 Measurement Principle 1

1.3 Design 1

1.4 Procedure Determining TDC 2

2 Application Area 3 3 System Components 5 3.1 Scope of Supply 5

3.1.1 TDC-Sensor 428 =TI0428A.01= 5 3.1.2 TDC-Sensor Set 428 =TI0428SETA.01= 5 3.2 Optional Accessories 6

3.2.1 Sensor Probes 6 3.2.2 Adaptor for Standard-Probe 428.10 6 4 Sensor Design 9 4.1 Sensor Electronics with Connection Cables and Balancing Unit 9

4.2 Probe with Clamping Set 9

4.3 Adaptors 9

5 Operation Principle 11 5.1 TDC-Sensor 428 11

6 Preparing the Measurement 13 6.1 Selection of Measurement Bore 13

6.1.1 Installation Position - Measuring Position 13 6.1.2 Typical Installation 14 6.1.3 Adaptor Design 17 6.2 Installing the Sensor Probe 20

6.2.1 Gap between Piston and Probe 20 6.2.2 Adjusting the TDC-Sensor Probe 21 6.3 Electrical Connections 23

6.4 Electrical Balancing 24

6.4.1 Purpose of Balancing 24 6.4.2 Prerequisite 24 6.4.3 Balancing Unit 25 6.4.4 Checking the TDC Signal Amplitude 26 6.4.5 Checking the TDC Signal for Interference 26 7 Measurement Procedure 29 7.1 Cylinder in Non-fired Operation 29

7.2 Measurement with AVL Indicating Equipment 29

7.3 Typical Signal Curves 30

8 Errors and Remedies 31 8.1 Possible Damage 31

8.2 Signal Influence at Gas Exchange 32

8.3 Typical Signal Signifying Touch with Piston 33

8.4 Sensor Probe Soiling 34

8.5 Sensor Probe Damage 34

8.6 Damage to the Sensor Probe Head 34

9 Technical Data and Dimensions 35 10 Appendix 39 10.1 CE Compliance 39

10.2 List of Figures 39

TDC-Sensor General Description

1  Operating Instructions in Brief

1.1  General

In the thermodynamic evaluation of pressure curves measured in internal combustionengines, the exact determination of the top dead centre (TDC) position is of greatimportance (e.g in IMEP-measurements)

Since the rigid construction of internal combustion engines is not ideal, a staticallydetermined TDC can involve uncertainties

1.2  Measurement Principle

The capacitive TDC-Sensor 428 is used to determine TDC dynamically in a motored ICengine or partially firing IC engine (the cylinder to be measured is unfired and the othersare fired)

The 428 TDC sensor can be installed in most engines in existing indicating, injection orspark plug bores

The 428 TDC sensor evaluates the variation in capacitance between the piston and thesensor probe head Using SMD technology, a specially developed electronic circuitdelivers an analogue signal corresponding to the piston lift when it is near TDC

The difference between TDC and trigger mark is calculated by determining the symmetryangle of the compression lift signal

1.3  Design

The TDC-Sensor 428 complete consists of the standard 260 mm sensor probe, the sensorelectronics which is directly mounted to the sensor probe with a 10 m connection cableand a clamping set For extra long sensor probe and mounting adaptors see ChapterOptional Accessories, Page 6

The sensor probe comprises a sensor element of the appropriate length and a sensorprobe head The sensor probe can be adjusted easily by means of the clampingmechanism The sensor probe is installed in existing engine bores with a suitable adaptor

The sensor electronic circuit is the same for all applications irrespective of sensor probelength and installation position

For analysing the TDC signal, the AVL Indicating Equipment Indimeter 619, Indiset 620,Indiset Advanced 631, Indimaster 670, can be used in conjunction with a suitable AngleEncoder (resolution 0.1 deg crank angle, i.e AVL 364/365 Angle Encoder)

1.4  Procedure Determining TDC

• Mount a suitable adaptor in one of the existing bores in the cylinder head

• Insert the sensor probe into the adaptor and then adjust the distance between sensorprobe head and piston

• Fix the sensor electronics to the sensor probe

• Connect the sensor electronics to an AVL Indicating Equipment or other evaluationequipment

• Adjust TDC signal zero line (using potentiometer in the balancing unit, piston atBDC)

• Carry out the measurement

TDC-Sensor General Description

2  Application Area

The AVL TDC-Sensor 428 is used to determine the precise position of TDC in dynamic operation Itcan also be applied for approximate static determination of TDC

The TDC-Sensor 428 standard model with 260 mm sensor probe is designed to fit most IC engines

up to truck engine size A 360 mm or 500 mm probe is available for larger engine sizes

The prerequisites for dynamic TDC determination are suitable bores in the IC engine (indicating-,spark plug- or injection bores) which can accommodate the sensor probe adaptors

Measurement-related requirements for installation position are given in Chapter Selection ofMeasurement Bore, Page 13

TDC-Sensor System Components

Sensor Electronics with connection cables and Balancing Unit 4028Z03 =BG 0297=

Sensor Probe, 260 mm long 428.10 =BO 0586=

Distributor 428 =EU 1726=

Clamping Set complete, comprising:

• Adjustement Piece 428.30 =YF 0456=

Knurled Nut 428.31 =YF 0457=

• Clamping Cone 428.20 =YF 0454=

Hexagonal Nut 428.21 =YF 0455=

• Fixing Nut 428.40 =YF 0453=

• Operating Manual 428 =AT0327E=

See Figure 9-1: Sensor Electronics 4028Z03, Figure 9-2: Sensor Probe 428.10 or 428.12,428.14, Figure 9-3: Clamping Set complete

As a supplement to the indicating equipment there is a TDC-Sensor Set which containsthe recommended minimum parts required, namely

• TDC-Sensor 428 complete =TI0428A.01=

• Extra Sensor Probe, 260 mm long 428.10 =BO 0586=

• Adaptor M14x1.25 428.51 =YF 0486=

• Adaptor M10x1 428.52 =YF0482=

• Adaptor sleeve 428.53 =YF0483=

3.2  Optional Accessories

Standard Probe 428.10 L = 260 mm

Probe for cylinder heads with deeper installations bores 428.12 L = 360 mm

Probe for cylinder heads with deeper installations bores 428.14 L = 5000 mm

3.2.2  Adaptor for Standard-Probe 428.10

The following adaptors are available for standard sensor probes L=260 mm) tobeinstalled in AVL Pressure Transducer bores

Figure 3-2: Adaptor 428.51 for spark plug bores with M14x1.25 thread

and indicating bores for pressure transducer with M14x1.25 thread

Figure 3-3: Adaptor 428.52 for spark plug bores M10x1 thread

and indicating bores for pessure transducer with M10x1 thread

Figure 3-4: Adaptor Sleeve for Adaptor AH08 and 8ZP32

(for pressure transducer in 10 mm adaptor design)

TDC-Sensor Sensor Design

4  Sensor Design

4.1  Sensor Electronics with Connection

Cables and Balancing Unit

The sensor electronics consists of a housing with permanent connector for the sensorprobe and a connection cable which is soldered to the pcb and fitted with a strain reliefcleat The output signal cable with BNC plug is 2 m long, the power supply cable 5 mlong and has a 5-pin plug mounted The balancing unit is included in the power supplycable 2 meters behind the sensor electronics

The 5-pin plug can be connected directly or via a relevant distributor with an AVL AngleEncoder 365 (364) (see Chapter Connection Probe and Sensor Electronics, Page 23)

The BNC plug must be connected via a 10 m long connecting cable (e.g E124-10) to the data acquisition system.

As the cable capacity influences the accuracy of the measurement, it is not possible to shorten or to extent the 10 m connecting cable.

Do not dismantle sensor electronics!

4.2  Probe with Clamping Set

The sensor probe consists of a sensor element and sensor probe head The sensorelectronics connector is mounted to the sensor probe and fixed with the fixing nut Theclamping set consists of a clamping cone with hexagonal nut, an adjustment piece withknurled nut and a fixing nut The sensor probe is fixed to the adaptor with the clampingcone (M14x1 thread) The adjustment piece is used to adjust the gap between piston andsensor probe head in defined increments (0 / 0.8 / 1.2 / 1.6 and 2.0 mm) in the direction

of the sensor axis

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TDC-Sensor Operation Principle

5  Operation Principle

5.1  TDC-Sensor 428

The sensor probe is fixed in the adaptor by the clamping cone The adjustment piece isthen to define the gap between piston and sensor probe head (see Figure 5-1: TDC-Sensor 428 Page 11) The sensor probe head and the piston are a capacitor Thecapacitance depends on the distance between both parts Variations in capacitance aredetected by a capacitive bridge circuit In Figure 5-2: Principal circuit diagram Page 11,C2 represents the capacitor formed by the sensor probe head and the piston

Square-wave pulses are applied to a capacitive bridge from an oscillator via circuitelements which are dependent on the output voltage If the capacitance varies, there is achange in the potential divider ratio in the sequential of capacitors (Cl + C2 or C3 + C4).This results in a change in the bridge quadrature component of voltage, which causes achange in the output voltage from the differential amplifier and a shift in potential (eland e2) This shift matches the amplitude of the pulses applied via the circuit elements

to the new capacitance conditions

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TDC-Sensor Preparations for Measurement

6  Preparing the Measurement

6.1  Selection of Measurement Bore

To install a sensor probe for dynamic determination of TDC, there must be a suitablebore in the cylinder head (indicating bore, spark plug bore or bore for injection nozzleholder), to that an adaptor can be mounted to accommodate the sensor probe

The measurement bore must meet the following criteria

6.1.1  Installation Position - Measuring Position

The measurement bore chosen should ideally be as close as possible to the free end ofthe crank shaft, i.e close to the angle encoder If the TDC sensor is installed at theflywheel side and the angle encoder at the free end, crank shaft torsion will have to betaken into consideration

• The bore axis should not be inclined more than 30 degrees from the piston axis

• The measuring position (sensor probe head - piston) should be at the piston surfaceperpendicular to the piston lift direction

• If this is not possible (e.g piston bowl), it must be endeavoured that as itapproaches TDC, the piston moves constantly closer to the sensor probe head Itmust be avoided, that due to the geometry of the piston bowl, the smallest distancebetween sensor probe head and piston, i.e the strongest signal, is reached beforethe TDC

• If the sensor probe head points towards an inclined piston bowl wall or the cone of

a „Mexican hat“ piston the transverse piston motion can lead to measurementerrors

• For high precision measurements, in order to reduce measurement error due totipping of the piston, ensure that the measuring position at the piston lies in thesame plane of symmetry as the axis of the piston pin

6.1.2  Typical Installation

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TDC-Sensor Preparations for Measurement

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TDC-Sensor Preparations for Measurement

The sensor probe is positioned and fixed by the adaptor that also must seale the bore Itmust also consist of an adjusment thread for the clamping cone It should not be made

of light or nonferrous heavy metal, but of steel (preferably stainless steel)

The adapter should be sturdily built The length L should not exceed 50 mm inmeasurement position in order to avoid too heavy vibration to the sensor electronicswhite operating the engine

Insert the adaptor directly into the indicating bore and use the same gasket asfor the pressure transducer (e.g AVL SG05) Installation in the engine,see Figure 6-2: Sensor probe in spark plug bore, Page 15



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Figure 6-4: Adaptor for indicating- or spark plug bores with M14x1.25 thread

For standard length of sensor probe (260 mm) AVL offers the Adaptor 428.51(see Chapter Adaptor for Standard-Probe 428.10, Page 6)

TDC-Sensor Operation Principle

5  Operation Principle

5.1  TDC-Sensor 428< /b>

The sensor probe... adjustment piece isthen to define the gap between piston and sensor probe head (see Figure 5-1: TDC-Sensor 428 Page 11) The sensor probe head and the piston are a capacitor Thecapacitance depends on...

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Figure 5-1: TDC-Sensor 428

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