Dynamometer: Theory and Application to Engine Testing

Copyright © 2012 by Jyotindra S. Killedar.

Library of Congress Control Number:        2012909642

ISBN:                 Hardcover                        978-1-4771-2007-1

                           Softcover                         978-1-4771-2006-4

                            Ebook                             978-1-4771-2008-8

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Contents

Preface

Part 1 DYNAMOMETERS

Chapter 1 What Is Dynamometer?

1.1 Introduction

1.2 Definition of the Dynamometer

1.3 History of the Dynamometer

1.4 Dynamometer—A Chronology of Innovation

1.5 The Word Dynamometer

1.6 Essential Features of Dynamometer

1.7 Speed Measurement of Dynamometer

1.8 Torque Measurement

1.9 Torque—turning force

1.10 Dynamometer Constant

1.11 Mounting of Dynamometer

1.11.1 Trunnion bearing

1.11.2 Flexural Support

1.11.3 Fixed Mounting

1.12 Scientific Accuracy of Dynamometers

1.13 BHP Concepts

Closure

Chapter 2 Dynamometer—Classification and Types

2.1 Introduction

2.2 Prony Brake Dynamometer

2.3 The Power Curve of the Prony Brake

2.4 Rope Brake Dynamometer

2.5 Fan Brake Dynamometer[2]

2.5.1 Power Curve of Fan Brake

2.6 Hydraulic Dynamometer

2.6.1 Hydraulic Dynamometer—Sluice gate Controlled (Constant Fill)

2.6.2 Hydraulic Dynamometer—Outlet Valve controlled (Variable Filled)

2.7 Eddy-Current Dynamometer—Dry Gap

2.8 Eddy-current Dynamometer—Wet Gap

2.9 DC Dynamometer

2.10 AC Dynamometer

2.11 Transmission Dynamometer

2.11.1 Epicyclical Train Dynamometer[1]

2.11.2 Belt Transmission Dynamometer[1]

2.11.2.1 Tatham Dynamometer

2.11.2.2 Von Hefner Belt Transmission Dynamometer

Closure

Chapter 3 Hydraulic Dynamometers

3.1 Introduction

3.2 Construction of Hydraulic Dynamometer

3.2.1 Construction of Sluice Gate Machine

3.2.2 Pressure-controlled Hydraulic Dynamometer

3.3 Water Movement Inside the Dynamometer

3.4 Inertia of Hydraulic Dynamometer and Its Effect

3.5 Power and Torque Envelopes

3.7 Method of Load Control

3.7.1 Sluice Gate Control

3.7.2 Pressure-controlled Dynamometer

3.7.2.1 Electric Servo

3.7.2.2 Electrohydraulic Servo Control

3.8 Cavitation in Hydraulic Dynamometer

Avoiding Cavitation

Effect of Cavitation

3.9 Selection of Dynamometer

3.10 Application of Hydraulic Dynamometer

Closure

CHAPTER 4 Eddy-current Dynamometer

4.1 Introduction

4.2 History of Eddy-current Dynamometer

4.3 Principle of Operation

4.4 Electrical Laws Associated with the Eddy-current Dynamometer

4.5 Construction of Eddy-current Dynamometer

4.5.1 Rotor and Shaft Assembly

4.5.2 Casing/Carcass Assembly

4.5.3 Baseplate Assembly

4.6 Inertia of Eddy-current Dynamometer

4.7 Power and Torque Envelopes

4.7.1 Power Curve of Eddy-current Dynamometer

4.7.2 Torque Curve of Eddy-current Dynamometer

4.7.3 Power Curve Comparison

4.8 Wet Gap Eddy-current Dynamometer

4.8.1 Advantages of the Wet Gap Dynamometer

4.8.2 Disadvantages of the Wet Gap Dynamometer

4.9 Air-cooled Eddy-current Dynamometer

4.10 Applications of Air-cooled Eddy-current Dynamometer

4.11 Dry Gap Twin Coil Eddy-current Dynamometers

Closure

Chapter 5 Magnetic Powder and Hysteresis Dynamometer

5.1 Introduction

5.2 Magnetic Powder Dynamometer

5.3 Power Curves of Magnetic Powder Dynamometer

5.4 Torque Curves of Magnetic Powder Dynamometer

5.5 Hysteresis Dynamometers

5.5.1 Operating Principles

5.5.2 Construction of Hysteresis Dynamometer

5.5.3 Power Curve of Hysteresis Dynamometer

5.5.4 Torque Envelope of Hysteresis Dynamometer

5.6 Comparison of Hysteresis, Eddy-current, and Powder Dynamometers

5.7 Typical Accuracies of Magnetic Powder and Hysteresis Dynamometer.

5.8 Applications of Magnetic Powder and Hysteresis Dynamometers

Closure

Chapter 6 Portable Dynamometers

6.1 Introduction

6.2 Portable Dynamometer

6.3 Construction of Portable Dynamometer

6.4 Cross Section of Portable Dynamometer

6.5 Power Curve of Portable Dynamometer

6.6 Typical Applications

6.7 Advantages of Portable Dynamometer

6.8 Applications of Portable Dynamometer

6.8.1 Engine Testing

6.8.2 Testing of the Engines Insitu Condition

6.8.3 Farm Tractor PTO Testing

Closure

Chapter 7 Direct Current (DC) Dynamometer

7.1 Introduction

7.2 Electrical Dynamometers

7.3 Principle of Operation

7.4 Rating of the DC

7.5 Construction of DC Machine

7.5.1 Trunnion Mounting

7.5.2 Fixed Mounting

7.6 Power and Torque Envelope

7.7 Inertia and Its Effect

7.8 Typical Accuracies of DC Machine/Dynamometer

7.9 Control System

7.9.1 Thyristor Drive Basics

7.9.2 Four-quadrant DC Drive

7.10 Basic Drive Operation

7.11 Changing the Direction of Rotation of DC Dynamometer

7.12 Stopping a Motor

7.13 Regeneration—Four-quadrant Operation

7.14 Emergency Breaking

7.16 Regeneration—Feedback to Mains

7.17 DC Dynamometer Application in Engine Testing

7.18 Types of Load Banks

Closure

Chapter 8 Alternating Current (AC) Dynamometer

8.1 Introduction

8.2 AC Electrical Dynamometers

8.3 Principle of Operation

8.4 Rating of AC Dynamometer

8.5 Construction of AC Dynamometer

8.5.1 Trunnion-mounted AC Dynamometer

8.5.2 Foot-mounted

8.5.2.1 Advantage of Foot-mounted Machines

8.6 Liquid-cooled AC Dynamometer

8.6.1 The Advantages of Liquid-cooled AC Dynamometer

8.7 Mounting of In-line Torque Transducer

8.8 Comparison of AC and DC dynamometers (Bare Machines)

8.9 Power and Torque Envelopes

8.10 Inertia of AC Dynamometer

8.11 Typical Accuracies of AC Machine

8.12 AC Drive Principles of Operation

8.12.1 AC Drive Basics

8.12.2 Converter and DC Link

8.12.3 Insulated Gate Bipolar Transistor (IGBT)

8.12.4 Converter and Control Logic

8.12.5 Pulse Width Modulation (PWM)

8.12.6 Control Panel

8.12.7 Dynamometer Application in Engine Testing

Closure

Chapter 9 Economics of Comparison

9.1 Introduction

9.2 Parameters Governing Selection of Dynamometer

9.3 Important Factors Influencing Selection of Dynamometer

9.4 Comparison of Hydraulic and Eddy-current Dynamometers

9.5 Water Supply System and Its Requirement

9.5.1 Influence of Water System on Working of the Hydraulic Dynamometer

9.7 Comparison of AC and DC Dynamometers

9.7.1 System Price

9.7.2 Drive Price and Maintenance Costs

9.7.3 Motor Price

9.7.4 Installation Cost

9.7.5 Efficiency

9.7.6 Power Factor

9.7.7 Harmonics

9.7.8 Performance

9.7.9 Degree of Protection for Motors

9.7.10 Modernizing Existing DC Drives [¹]

9.8 Control Accuracy and Response

Closure

Chapter 10 Control Modes—What Do We Control?

10.1 Introduction

10.2 Open-loop mode

10.2.1 Open-loop Characteristics—Hydraulic Dynamometer

10.2.2 Open-loop Characteristics—Eddy Dynamometer

10.3 Closed Loop

10.3.1 Speed Constant Mode

10.3.2 Torque Constant Mode

10.3.3 Power Law Mode

10.4 Application of Modes for Engines

10.5 Dynamometer Modes with Relation to Torque Envelope

10.5.1 Speed Constant Mode (N = Constant)

10.5.2 Torque Constant Mode (M = Constant)

10.5.3 Power Law Mode M(N2)

10.6 Selection of Right Dynamometer Mode

10.7 Manifold Vacuum/MAP Option Control Modes

10.8 Bump-less Mode Transfer

10.9 Role of PID Controller

10.10 The Methodology to Set Up a PI Controller

Closure

Chapter 11 Dynamometer: Torque and Power Measurement Accuracy

11.3 Calibration of Measured Parameters

11.4 What Do We Understand by Traceability?

11.5 Torque Measurement

11.6 Torque Transmission Process

Conclusion

11.7 Errors Associated with Torque Measurement

Closure

Chapter 12 Correction Factor and Horsepower

12.1 Introduction

12.2 How correction factor and Horse power is related?

12.3 The STP and NTP conditions

12.3.1 STP—Standard Temperature and Pressure

12.3.2 NTP—Normal Temperature and Pressure

12.4 Use of correction factors

12.5 Horsepower and Torque:

12.6 Effect of altitude on the power

12.7 Effect of Humidity on the power.

12.8 Effect of Temperature on the Power

12.9 Power Correction Factors

12.10 Society of Automotive Engineers

12.10.1 SAE J1349 Update:

12.10.2 Derivation of SAE Correction Factor Formula

12.11 DIN—70012 Method.

12.12 JIS D 1001 Method

12.13 ISO 1585 Method

12.14 Correct sensing of parameters—Ambient Air temperature, Pressure and RH in Test cell.

Closure:

PART II Data Acquisition and Control System

Chapter 13 The Sensors and Transducers

13.1 Introduction

13.2 Thermocouples

13.2.1 Theory of Operation

13.2.2 Factors Affecting the Accuracy of the Thermocouple

13.2.3 Identification for Insulated Thermocouple Wire

13.2.4 Thermocouple Wire

13.2.5 Accuracy of Thermocouple

13.2.6 Thermocouple Grade and Extension Grade Wire

13.2.7 Types of Thermocouples Commonly Used

13.2.8 Cold Junction Compensation (CJC)

13.2.9 Precautions and Considerations for Using Thermocouples

13.2.10 Connection Problems

13.2.11 Lead Resistance

13.2.12 Decalibration

13.2.13 Noise

13.2.14 Common Mode Voltage

13.2.15 Thermal Shunting

13.3 Resistance Temperature Detector (RTD)

13.3.1 Theory of Operation

13.3.2 Linearization of RTD

13.3.3 Advantages of RTD

13.2.4 Disadvantages of RTD

13.3.5 Tolerance and Accuracy

13.3.6 Comparison of Thermocouple and RTD

13.4 Strain Gauge

13.4.1 Theory of Operation

13.4.2 Factors Influencing Selection of Strain Gauges

13.4.3 How Strain Gauge Is Attached to Specimen?

13.4.4 Strain Measurement Using a Wheatstone Bridge Circuit

13.3.5 Signal Conditioning for Strain Gauges

13.5 Load Cell

13.5.1 Theory of Operation

13.5.2 Load Cell Operating Principles

13.5.3 Load Cell Classification Based on Working Principle

13.5.4 Types of Load Cells Classified Based on Construction

13.5.5 The Important Terminology of the Load Cell

13.6 Pressure Transducer

13.6.1 Theory of Operation

13.6.2 Gauge Pressure

13.6.3 Atmospheric Pressure

13.6.4 Absolute Pressure

13.6.5 Standard Atmospheric Pressure

13.6.6 Pressure Measurement Devices/Instruments

13.6.6.1 Manometers

13.6.6.2 Pressure Gauges

13.7 Rotary Torque Transducer

13.7.1 Theory of Operation

13.7.2 Mechanical Design of Torque Transducer

13.7.3 Electrical Design

13.7.5 Coupling Requirements for Torque Transducer

13.7.6 Mechanical Calibration

13.7.7 Electrical Calibration

13.8 Magnetic Pickup

13.8.1 Magnetic Pickup with 60-toothed Wheel

13.8.2 Why 60-toothed Wheel Is Used?

13.8.3 Tachogenerator

13.8.4 Encoder

13.9 Environmental Measurements

13.9.1 Ambient Air Intake Temperature

13.9.2 Barometric Pressure

13.9.3 Relative Humidity

13.9.3.1 Measurement of Relative Humidity

Closure

Chapter 14 Automation of Testing Process and Measurements

14.1 Introduction

14.2 Different Levels of Automation

14.3 Strategies for Automation

14.4 Classification of Test Cell Automation

14.5 Automation of Control System

14.5.1 Engine Throttle Controller

14.5.2 Engine Shutdown Actuator

14.5.3 Computerized Automation of Testing

14.6 Automation of Engine Handling

14.6.2 Automatic Driveshaft Connection

14.6.3 Automated Guided Vehicles

14.7 Docking Trolleys and Carts

14.8 Overhead Conveyor and Pallets

Failed Engine Requiring Repair

14.9 Automation of Auxiliary Equipment

14.9.1 Why Do We Need Temperature Controllers?

14.9.2 Elements of Temperature Controller

14.9.3 How Controller Works

14.10 Engine Oil Temperature Controller (EOTC)

14.14 Engine Water Temperature Controller (EWTC)

14.12 Engine Fuel Conditioning Unit

Closure

Chapter 15 Basics of Dynamometer Data Acquisition and Control System

15.1 Introduction

15.2 What Is Data Acquisition?

15.3 What Data Acquisition Does?

15.4 Where Do We Use Data Acquisition and Control System?

15.5 The Elements of Data Acquisition Systems

15.5.1 Sensor

15.5.2 Signals

15.5.3 Data Acquisition Hardware

15.5.4 Data Acquisition Software

15.6 Data Acquisition Terminology

15.7 Types of Data Acquisition Systems

15.7.1 Wireless Data Acquisition Systems

15.7.2 Serial Communication Data Acquisition Systems

15.7.3 USB Data Acquisition Systems

15.7.4 Data Acquisition Plug-in Boards

15.8 Acquisition Channel Definitions

15.9 Alarm Annunciation

Window Alarm

15.10 Configuration of Alarms as Failsafe and Nonfailsafe

15.11 Alarm Trip Choice—Hard or Soft?

15.12 Types of Relays

15.13 Audiovisual Indications for Tripping

Auto Reset Sequence

15.14 Engine Data Acquisition and Control System (EDACS)

15.15 Executing the Automated Test as Programmed

15.16 Display of Data—Analog and Digital Indicators

15.17 Recording and Printing of Data

15.18 Management and Analysis of Data

Closure

Part III Modern Test Cell Concepts

Chapter 16 Engine Test Cell and Its Evolution

16.1 Introduction

16.2 Types of Test Cells

16.3 Noise in Test Cell

16.3.1 What Is Noise?

16.3.2 What Is dBA?

16.3.3 What Is NRC?

16.3.4 What Is Sound Transmission Class?

16.3.5 How to Interpret the dBA?

16.4 Test Cell Ventilation

16.5 Test Cell—Engine Exhaust Handling

16.6 Water Supply Systems

16.6.1 pH Value of Water

16.6.2 Purity of Water

16.6.3 Water Quantity

16.6.4 Cooling Towers

16.7 Compressed Air System

16.7.1 Air Quality

16.7.2 Air Quantity

16.7.3 Air Pressure

16.8 Fuel System

16.9 Engine Oil Supply System

16.10 Engine and Dynamometer Foundation

16.10.1 Foundation

16.10.2 Resonance

16.10.3 Concrete

16.10.4 Foundation Isolation

16.10.5 Foundation Bolts

16.10.6 Holding Down Bolts

16.10.7 Typical Foundation Hole

16.10.8 Dynamometer Baseplate Mounting

16.11 Lighting System

16.12 Communication System

16.13 Fire Fighting System

Closure

Chapter 17 Measurements of Modern Engine

17.1 Introduction

17.2 Fuel Consumption Measurement

17.2.1 Flow Meter

17.2.2 Types of Flow Meter Used in Engine Testing

17.2.3 Selection Criteria of a Flow Meter

17.2.4 Flow Measurement Orientation

17.2.5 Types of Fuel Consumption Meters

17.2.5.1 Orifice-type Flow Meter

17.2.5.2 Rotameter

17.2.5.3 Volumetric Fuel Consumption Meter (Pipette Type)

17.2.5.4 Gravimetric Fuel Measurement

17.3 Air Flow Measurement

17.3.1 Intake Air Measurement-Hot Wire Anemometer Method

17.3.2 Intake Air Measurement—Pitot Tube and Differential Pressure Transmitter

17.3.3 Intake Air Measurement—Air Box Method

17.4 Blow-by Measurement

17.4.1 What Is Blow-by?

17.4.2 How to Measure Blow-by?

17.4.3 How Much Blow-by Is Normal for an Engine?

17.4.5 Interpretation of Blow-by Readings

17.5 Oil Consumption Measurement

17.5.1 What Causes Excessive Oil Consumption?

17.5.2 Measuring Oil Consumption

17.5.3 Oil Consumption by Slow Flow Meter

Closure

Chapter 18 Basics of Engine Testing

18.1 Introduction

18.2 Definition of an Engine

18.3 Classification of the Engines

18.4 Major Components of an IC Engine

18.6 Two-stroke Engines

18.7 The Four-stroke Engines

18.8 Comparison of Four-stroke and Two-stroke Engines

18.9 Testing Classification

18.10 Testing Procedure

18.11 What Do We Test Using Dynamometer and Associated Instrumentation?

18.11.1 Engine Power and Torque Curves

18.11.2 Indicated Horsepower

18.11.3 Brake Horsepower

18.11.4 Mechanical Efficiency

18.11.5 Frictional Horsepower

18.11.5.1 Methods to Establish FHP

18.11.5.1.1 Willan’s Line Method

18.11.5.1.2 Morse Test

18.11.5.1.3 Motoring test

18.11.6 Fuel Consumption

18.11.6.1 Volumetric Fuel Measurement

18.11.6.2 Gravimetric Fuel Measurement

18.11.7 Air Consumption

18.11.8 Brake Thermal Efficiency

18.11.9 Indicated Thermal Efficiency

18.11.10 Brake Mean Effective Pressure

18.12 Heat Balance of the Engine

18.13 Engine Testing In Industry

18.13.1 Research and development

18.13.2 Production Testing

18.13.3 Quality Audit Testing of Engines

18.13.4 Type Testing

Closure

Bibliography:

Chapter 19 Test Cell Essentials

19.1 Introduction

19.2 Dynamometer Accessories

19.2.1 Dynamometer Water Inlet Filter

19.2.1.1 Y-type Strainer

19.2.1.2 Bucket Type Filter

19.2.1.3 Magnetic Filter

19.3 Universal Engine Mounting Test Beds

19.3.1 T-slotted Bedplates (CI and MS)

19.4 Cardan Shaft

19.5 Shaft Guard

19.6 Transducer Box

19.7 In-cell Control Panel

19.8.1 In-Line Mounted Electric Starting Motor

19.8.2 Piggyback-Mounted Starting Motor

19.8.3 Starter Motor Mounted on Dynamometer Nondrive but Offset to Center

19.8.4 Starting Motor Mounted Beneath the Dynamometer

19.9 Conventional Method

19.10 Nonelectrical Starting Systems

19.11 Load Throw Off Valve

19.12 Throttle Actuator and Controller

19.13 Diesel Engine Shutdown Actuator

19.14 Calibration Weights and Arm

19.15 Speed and Torque Indicator

19.16 Weather Station

Closure

Chapter 20 Applications of Dynamometer

20.1 Introduction

20.2 Tractor PTO Testing

20.3 Draw Bar Pull Testing—Towing Dynamometer

20.4 Vertical Motor and Vertical Turbine Testing

20.4.1 Vertical Dynamometer Calibration

20.4.2 Vertical Alignment

20.5 Locked Rotor Test

20.6 Tandem Dynamometer

20.6.1 Single Engine Testing

20.6.2 Dual Engine Testing

20.7 Outboard Motor Testing

Closure

Chapter 21 Driveshaft and Vibrations

21.1 Introduction

21.2 Terminology in Drive shaft selection

21.3 Selection procedure

21.3.1 Cardan Shaft Selection

21.3.2 Torque rating of Cardan Shaft

21.3.3 Speed rating of the cardan shaft

21.4 Calculation of torsional vibrations

21.4.1 Engine Orders

21.4.2 Natural Frequencies of Torsional Vibration

21.5 Holzer method for torsional vibration analysis:

21.5.1 Three Mass Systems

21.5.2 Two Inertia systems

21.6 Engine and dynamometer foundation:

21.6.1 Schematic 1—Engine and dynamometer firm on hard foundation

21.6.2 Schematic 2—Engine flexible mounted on hard foundation and dynamometer firm on hard foundation.

21.6.3 Schematic 3—Engine Hard mounted on flexible Engine stand and dynamometer firm on hard foundation.

21.6.4 Schematic 4:—Engine and Dynamometer hard on flexible foundation.

21.6.5 Schematic 5:—Engine flexible mounting and Dynamometer hard and both flexible mounted on common foundation.

21.6.6 Schematic 6:—Engine stand flexible mounting and engine hard on engine stand. Dynamometer hard on its own foundation. Engine stand and dynamometer foundation both flexible mounted on foundation.

21.6.7 Schematic 7:—Engine flexible on engine stand which is flexible on foundation. Dynamometer firm on its own foundation

Closure:

Chapter 22 Air Intake and Exhaust Extraction Systems

I. Air Intake System

22.1 Introduction

22.2 The Purpose of Combustion Air Handling Unit—CAHU

22.3 Combustion Air Handling Unit—CAHU

22.4 Air-Fuel Ratio

22.5 Lambda

22.6 What Is the Effect of Changing the Air-Fuel Ratio?

II Engine Exhaust Extraction

22.7 Introduction

22.8 What Is the Exhaust?

22.9 Exhaust Blowdown

22.10 Exhaust Stroke

22.11 The Exhaust Backflow

22.12 The Importance of Correct Back Pressure

22.13 Exhaust Extraction from the Engine Test Cell

22.13.1 Underground Extraction System

22.13.2 Overhead Extraction Systems

22.14 Exhaust Extraction from the Vehicle Test Cell

22.14.1 Telescopic System

22.14.2 Common Rail System

22.15 The Essential Elements of Exhaust Extraction

22.15.1 Exhaust Capture Nozzles

22.16 Exhaust Crush-proof Hoses

22.17 Fan Motor Assemblies

22.18 Hose Reel

22.19 Spring Balancer for Hose

22.20 Multipoint System

22.21 Design Considerations in Exhaust Extraction System

22.21.1 Exhaust Back Pressure

22.21.2 Pipes and Flexible Pipes

22.21.3 Insulation for Pipes

22.21.4 Expansion Joints and Bellows

22.21.5 Exhaust to Atmosphere

22.21.6 Condensate Extraction

Closure

Appendix -1 Power calculation formulae

Appendix II Engine terminology

Appendix III Pressure Units

Appendix IV Temperature Conversion

Appendix V Torque Conversion

Appendix VI Permissions and Approvals

Dedication

To My Guru:

To My parents:

My mother, Umadevi Killedar and my Father, Shankarrao Killedar

My in laws:

Sadanand Desai and Tulasi Desai

To My Family:

For my wife, Smruti Jyotindra Killedar

For my son: Amogh Killedar

My beloved sister Gita Bajirao Patil

Preface

The subject of dynamometer and engine testing is complex, and engines are getting more and more complicated with the involvement of modern technology. The low fuel consumption and low exhaust emissions without compromising the performance are the driving factors for the most modern engines. The testing of these modern engines is becoming more complex in nature as technology advances.

In olden days, the engines were tested in open shed probably at the back of the assembly line. The modern test cells are complex and full of complex electronics and dedicated instrumentation assigned to measure targeted parameters. Computers and robotic mechanisms have taken the place of manual engine testers. More sophisticated test cell management is now in place to evaluate the performance of modern engines.

I started my career in dynamometer field way back in 1984 and continued till 2003. My total experience of thirty-two years reinforced my knowledge in industrial products such as compressors, industrial pumps, dynamometers, and material handling equipment and as software consultant.

I encountered a number of difficulties while I was new in dynamometer field. Aspiring new technology was a challenge as there were very few publications dedicated to dynamometers and engine testing. Moreover, I noticed that an incumbent from the technical college entering the engine and dynamometer field as a novice had to face many challenges in acquiring required knowledge to understand the complex instrumentation and mechanisms. Even today, many engineering and technical schools do not teach the subject of engine testing in required depth.

I realized the need for a proper book that will cater to the needs of the commissioning engineers, service engineers, sales and application engineers, engineers in automotive field, as well as new incumbents in this field.

I decided to put forward my experience and my thoughts on dynamometers in the form of a small book. I dreamed of writing the book during my tenure as engineer in the field of dynamometer in 1984 when I initiated my career in this field. Today, I feel satisfied to fulfill this dream.

Recently, I came across a couple of books that are more oriented toward engine testing. I decided to write my book more oriented toward the dynamometers, their various types, and their application in engine testing.

This book is purely based on my experience and my thoughts. Since 1984, I worked with a few world-class companies manufacturing dynamometers and most modern instrumentation. While writing the book, I realized that this is a herculean task. Preparing the manuscript, drawings, and images was a time-consuming work. This task would not have been completed without the support and inspiration of my wife, Dr. Smruti Killedar (MSc, PhD), and my son, Amogh. They practically relieved me from my domestic duties.

My other family members Dr. Laxmi Desai (MSc, PhD) and Yogesh Meghrajani (ME in electronic engineering) contributed by way of valued suggestions to make this treatise happen. Ms. Dolly Sudhir (MSc) and Mr. Sudhir (BCom, MBA) helped and shared my responsibilities. Mrs. Sujata Joshi (MA, LLM) and Mr. Madhukar Joshi (BA, LLM), successful lawyers, helped me in taking care of legal matters. My niece, Nisha Patil (DEE, BE in electronics), and nephew, Kamlesh Patil (DERE, BE in electronics), helped me in compiling my data in the right order.

Many of my friends who worked in dynamometer field were kind enough to advice and guide me through their active support and suggestions. It is worth mentioning their names for their suggestions and their dedication to dynamometer and engine testing field for more than ten years. They are Rajendra Phadtare, Sanjay Vhawal, Arvind Bawkar, Baban Gaikwad, Vijay Vaidya, Ajit Raibagi, and Sanjeev Keskar, who have shared of my experiences in the dynamometer and engine testing field over the last ten years and kept me up to date. I thank Mr. Volker Leismann and Rohit Nath from Schenck Avery (former name). I am also thankful to my ex-colleagues at AVL India who shared their knowledge during my tenure in AVL India.

I worked in the world-class dynamometer-manufacturing companies, namely, Saj Test Plant Pvt. Ltd. India, Schecnk Avery Ltd., and AVL India. I am especially thankful to Mr. Prakash Jagtap, chairman and managing director, who gave me the opportunity to learn about various dynamometers and instrumentations. His inspiration lighted a lamp in me to learn new things.

I am also thankful to my friend Berteau Joisil (MSME) for correcting the electrical and instrumentation related information in the book.

The author has made an attempt to cover the required topics for the entry level personnel in the field of dynamometer and engine testing. It is impracticable to cover every aspect of engine testing in the one single book like this. For the benefit of the readers a certain books and technical papers are recommended at the end of each chapter under the heading of Further reading. The few chapters have the web sites mentioned under the bibliography. The names of the web sites are mentioned without mentioning the actual URLs as they are dynamic in nature and keep changing.

I welcome suggestions and comments from readers.

Part 1

DYNAMOMETERS

Chapter 1

What Is Dynamometer?

1.1 Introduction

In today’s modern world, the IC engines or any prime movers are tested for its performances such as power and torque developed. To test the performance of these prime movers, dynamometers and associated instrumentation are used. The installations of dynamometers have become the important part of the automotive industry. The subject of dynamometer seems to cause more concern, many misunderstandings, and notions. There are three methods of testing an automotive engine in general, and they are

1. testing an engine using dynamometer

2. testing a vehicle with engine under consideration on chassis dynamometer

3. running the vehicle on test track.

1.2 Definition of the Dynamometer

1. A device for measuring the torque, force, or power available from a rotating shaft. The shaft speed is measured with a tachometer, while the turning force or torque of the shaft is measured with a scale or by another method. Power may be read from the instrumentation or calculated from the shaft speed and torque.

2. It is an apparatus for measuring force or power, especially one for measuring mechanical power, as of an engine.

3. It is an instrument for measuring force exerted by men, animals, and machines. The name has been applied generally to all kinds of instruments used in the measurement of a force, as for example, electric dynamometers, but the term specially denotes apparatus used in connection with the measurement of work or in the measurement of the horsepower of engines and motors.

The most common use of the dynamometer is in determining the power of an electric motor or engine of a car, truck, or other vehicle. A dynamometer that connects to the engine crankshaft is an engine dynamometer. One that has rollers turned by the vehicle drive wheels is a chassis dynamometer; this type is widely used in the automotive industry for mileage accumulation, emissions, fuel economy, and performance testing of cars and trucks.

In this book, our discussions are mainly concentrated on engine dynamometer used for engine/motor testing.

1.3 History of the Dynamometer

The dynamometers are being used to measure the power since long. During the eighteenth century, James Watt introduced a unit of power to compare the power of his steam engines with a more familiar source of work. This unit of power became known as horsepower. It was defined as the amount of power required to move a 550-pound weight up to one foot in one second.

Figure 1.1 Work done.

The first device used probably date back when Gaspard de Prony invented the Prony brake circa 1821. The de Prony brake (or Prony brake) is considered to be one of the earliest dynamometers. Over the next two hundred years, the Prony brake dynamometer and variations of same were developed to measure engine horsepower. Modern day versions of these brake dynamometers are still in use today.

1.4 Dynamometer—A Chronology of Innovation

1. Gaspard de Prony invented the de Prony brake in 1821 in Paris. The de Prony brake (or Prony brake) is considered to be one of the earliest dynamometers.

2. In 1838, Charles Babbage, known to historians as the father of the computer, introduces a dynamometer car to measure the pulling power of English railroad locomotives.

3. William Froude with the invention of the hydraulic dynamometer in 1877, and first commercial dynamometers were produced in 1881 by their predecessor company, Heenan & Froude.

4. In 1921, Professor E. V. Collins of Iowa State College develops a draft horse dynamometer, used to measure a horse’s capability to pull the era’s heavy metal farm implements.

5. In 1928, the German company Carl Schenck Eisengießerei & Waagenfabrik built the first vehicle dynamometers for brake tests with the basic design of the today’s vehicle test stands.

6. In 1930, using designs pioneered through collaboration with Rudolph Diesel, John Taylor forms the Taylor Dynamometer and Machine Company to produce engine dynamometers.

7. The eddy-current dynamometer was invented by Martin and Anthony Winther in about 1931. At that time, DC motor/generator dynamometers had been in use for many years. A company founded by the Winthers, Dynamatic Corporation, manufactured dynamometers in Kenosha, Wisconsin, until 2002.

8. In 2002, Dyne Systems of Jackson, Wisconsin, acquired the Dynamatic dynamometer product line. Starting in 1938, Heenan and Froude manufactured eddy-current dynamometers for many years.

9. The first popular, true high speed, computer-controlled, eddy-current motor cycle chassis dynamometer was produced by Factory Pro Dynamometer of San Rafael, CA, USA, in 1990.

1.5 The Word Dynamometer

The word dynamometer is derived from a Greek word dunamis meaning power and meter means measure, that is, dunamis + metron = dynamometer.

1.6 Essential Features of Dynamometer

If we think about a good dynamometer which serves the purpose of the engine testing, then the following four essential features are important:

• means of controlling torque

• means of measuring torque

• means of measuring speed

• means of dissipating power.

1.7 Speed Measurement of Dynamometer

The speed in dynamometer is measured by either a mechanical tachometer or an electronic device. In case of an electronic device, the speed measurement consists of a magnetic pulse sensor working in conjunction with a geared wheel generally having sixty teeth. The pulses generated are processed and displayed by electronic digital indicator. In some cases, where accuracy is of utmost importance, an optical encoder is used.

1.8 Torque Measurement

The concept of torque is important enough to be clarified. Actually, it is the direct result of the load of the spring or weight. Its distance from the axis of rotation is also responsible for determining the torque. In reality, dynamometers are used to calculate the production of torque by an engine.

1.9 Torque—turning force

This is also called moment of a force, in physics—the tendency of a force to rotate the body to which it is applied. The torque, specified with regard to the axis of rotation, is equal to the magnitude of the component of the force vector lying in the plane perpendicular to the axis, multiplied by the shortest distance between the axis and the direction of the force component, regardless of its orientation. The following figure shows how the torque is understood.

Figure 1.2—Torque

Courtesy of HyperPhysics by Rod Nave, Georgia State University".

Dynamometers, aka dynos, are brakes used to measure the power of an engine at a given speed. The torque of an engine is determined by a complex measuring mechanism and reaction transferred by the dynamometer to measuring mechanism. Dynamometer manufacturers construct their products using basic components, namely, frame, trunnion bearings, absorption unit, and torque measuring device.

1.10 Dynamometer Constant

As discussed earlier in this chapter by definition, torque is derived quantity. It is a product of force applied and distance from the center to the point of application of the force. Generally, if the force is applied at the circumference of the rotating disk, then the distance between the center of disk and the point of application is radius of the disk under consideration.

Thus, torque T = force (f) × distance (l)

Or torque T = force (f) × radius (r)

Or Torque T = Force (f) x Radius (r)

..................................................1.1

The constant "K" in the equation is known as dynamometer constant.

1.11 Mounting of Dynamometer

The main casing of dynamometer consists of a power absorbing unit. In case of hydraulic dynamometer, it will be rotor and pair of stator and controlling mechanism, and in case of eddy-current dynamometer, it is a rotor, excitation coil, and cooling chamber. This main chamber or casing is also called as cradle.

1.11.1 Trunnion bearing

A pedestal with trunnion bearings is either bolted to baseplate, or they are integral part of baseplate as per the proprietary designs of different manufacturers. The dynamometer cradle is mounted between the pair of the trunnion bearings. This gives the freedom to oscillate when a reaction force acts on cradle as virtue of absorbed power.

Trunnion is nothing but pivot forming one of a pair on which something is supported. Here in this case, a dynamometer carcass is supported which is free to oscillate and transfer the reaction force to the measuring mechanism. The movement is limited by torque arm connected to the side of housing and connected to the torque measuring system. The advantage of trunnion bearing is that it is the simplest type of cradle mounting with freedom of movement for the carcass.

Trunnion bearings located between the ends of the dynamometer housing or carcass, and a set of pedestals do not rotate. They do, however, allow the carcass to rotate slightly for torque measurements. Since bearings and lubricant directly affect performance and accuracy of dynamometer, trunnion bearings should be inspected and rotated frequently. Grease-lubricated trunnion bearings do not require periodic lubrication. However, if grease becomes dry or lumpy, it should be flushed and replaced.

Figure 1.3 Trunnion mounting.

The disadvantage of the trunnion bearing is that after a long use, they try to be sticky. This is mainly because of their minimal movement. This is called the brinelling effect.

Some specially designed dynamometers consist of hydrostatic trunnion bearings, referred to as lift trunnion bearings. They are oil pressure lift-type sleeve bearings used to reduce trunnion bearing friction to a negligible value. This in turn typically improves system accuracy. Bearings of this type are oil lubricated with high pressure oil piping system to circulate oil through the bearings and support the carcass on a film of oil as long as the high pressure oil is supplied. Carcass floats during the operation.

1.11.2 Flexural Support

The dynamometer housing is cradle mounted in a flexure support on the frames. The