automotive engineering higher · automotive engineering: higher course 1 note of changes to...

AUTOMOTIVE ENGINEERINGHigher

Fourth edition – published February 2001

Automotive Engineering: Higher Course 1

NOTE OF CHANGES TO ARRANGEMENTS FOURTH EDITIONPUBLISHED FEBRUARY 2001

COURSE TITLE: Automotive Engineering (Higher)

COURSE NUMBER: C029 12

National Course Specification

Course Details: No changes

National Unit Specification:

D154 12 Secondary/Chassis Systems Changes have been made to this unit to clarify theneed for calculations in relation to baking efficiencyand brake testing

D153 12 Internal Combustion Heat Engines No changes

D155 12 Vehicle Management Systems No changes

Administrative Information

Publication date: February 2001

Source: Scottish Qualifications Authority

Version: 04

© Scottish Qualifications Authority 2001

This publication may be reproduced in whole or in part for educational purposes provided that no profit is derived fromreproduction and that, if reproduced in part, the source is acknowledged.

Additional copies of this course specification (including unit specifications) can be purchased from the Scottish QualificationsAuthority for £7.50. Note: Unit specifications can be purchased individually for £2.50 (minimum order £5).

2

National Course Specification

AUTOMOTIVE ENGINEERING (HIGHER)

COURSE NUMBER C029 12

COURSE STRUCTURE

This course comprises three mandatory units as follows:

D153 12 Internal Combustion Heat Engines (H) 1 credit (40 hours)D154 12 Secondary/Chassis Systems (H) 1 credit (40 hours)D155 12 Vehicle Management Systems (H) 1 credit (40 hours)

In common with all courses, this course includes 40 hours over and above the 120 hours for thecomponent units. This is for induction, extending the range of learning and teaching approaches,support, consolidation, integration of learning and preparation for external assessment. This time isan important element of the course and advice on its use is included in the course details.

RECOMMENDED ENTRY

While entry is at the discretion of the centre, candidates would normally be expected to have attainedone of the following:

• Scottish Group Award at Level 3 in a related area• Intermediate 2 Structures together with Mathematics or Physics at Intermediate 2 or above• Standard Grade in Technological Studies with either Mathematics or a science at grade 3 or

above• equivalent National units


National Course Specification (cont)

COURSE Automotive Engineering (Higher)

CORE SKILLS

This course gives automatic certification of the following:

Complete core skills for the course None

Core skills components for the course Critical Thinking Int 2

For information about the automatic certification of core skills for any individual unit in this course,please refer to the general information section at the beginning of the unit.

Additional information about core skills is published in Automatic Certification of Core Skills inNational Qualifications (SQA, 1999).


National Course Specification: course details


RATIONALE

Technological development creates an ever-changing engineering industry which has to compete in acompetitive market place. Automotive engineering has to respond to customer demand, economics,environmental considerations and performance as well as the adoption of new technological advancesin terms of materials, design, fuel efficiency, safety and ergonomics.

Successful completion of the course will enhance the technological capability of the candidate byproviding significant insight into the application of engineering principles in the modern motorvehicle. The course provides a balanced treatment of vehicle electrical systems, electronics,hydraulics, mechanics and control in which practical investigation features strongly.

The aim of the course is to develop knowledge and understanding of the main technological systemsof the modern vehicle.

The course aims to develop:

• knowledge of modern vehicle systems in terms of efficiency, performance and environmentalconsiderations

• the ability to measure and diagnose faults on vehicle systems and perform service adjustmentsto meet manufacturers’ requirements

• understanding of vehicle system operating principles• understanding of the application of electronic and programmed control in maintaining optimum

vehicle performance

In addition to the above the course will also contribute to the wider curriculum by helping thecandidate to develop:

• an appreciation of modern engineering principles in a real situation• knowledge of how design factors affect the performance and efficiency of engineering systems• self-confidence, planning, organisational and problem-solving skills

Completion of the course will, in addition, provide the candidate with a background of knowledgewhich would prepare them for studies in a variety of other technology-related areas or to applyprinciples, knowledge and a range of general transferable skills in many industrial contexts.

COURSE CONTENT

All of the course content will be subject to sampling in the external assessment.

Within the vocationally specific material in the course there are elements which are common to manyother vocational areas. For example, the course considers ratios, capacities, kinetic energy, friction,torque, power, speed, chemical change, potential energy, heat, principles of gearing, energyconversion, Hooke’s law, Ohm’s law, geometry, efficiency, pressure, force and area, centre ofgravity, electromagnetic induction, potential dividers and binary code.


National Course Specification: course details (cont)


The course is divided into three main areas: internal combustion engines, secondary/chassis systems,which include transmission, brakes, steering and suspension; and vehicle management systems. Allthree units can be taught independently where the award of Higher is not the intended outcome.However, the candidate will benefit from a course approach which provides greater integration.

SUMMARY OF COURSE CONTENT

Internal Combustion Heat Engines (H)This unit introduces the candidate to engine terminology and operating cycles as an initialconsideration and proceeds to investigate the combustion processes associated with SI (sparkignition) and CI (compression ignition) engines. It also provides a comparison of engine types andarrangements. It allows the candidate to consider the efficiency of engine operation and the effects ofservice adjustments upon efficiency, emissions and economy. In addition there will be considerationof engine emissions, the advantages to be gained by the incorporation of variable valve timing and itseffect upon engine operation, electronic engine control (which if selected for consideration, providesan area of integration with the unit on vehicle management systems), and a comparison exerciserelative to engine types and their operating characteristics. There then follows an investigation ofengine condition measurement and power and torque outputs.

Finally the candidate is provided with the opportunity to apply service adjustments to engines.

CONTENT STATEMENTS

Internal Combustion Heat Engines (H)The content statements given in the left-hand column of the table below describe in detail what thecandidate should be able to do in demonstrating knowledge and understanding.

The right-hand column gives suggested contexts, applications, illustrations and activities associatedwith the content statement.

Knowledge and understanding Contexts, applications, illustrations and activities

1 Engine terms. SI, CI, stroke, bore, firing point, swept volume,clearance volume, TDC (top dead centre), BDC(bottom dead centre), CC (cubic capacity),compression ratio, torque, power, RPM(revolutions per minute), firing order.

2 Engine cycles of operation. 4 stroke, 2 stroke and rotary cycles (SI only).Firing point and valve/port timing.

3 Comparison and evaluation of enginetypes.

4 stroke SI and CI engines, 2 stroke and 4 stroke SI,4 stroke SI and rotary SI engines.





4 Combustion processes and commonfaults.

SI and CI combustion processes. Energy release.Cylinder pressures and temperatures.

Relationship PV/T (pressure/volume/temperature).

5 Engine measurement. Oil pressure test, compression test, cylinder leakagetest, power balance test, cooling system pressuretest.

Power testing to include readings taken from anengine dynamometer. Power and torquecharacteristics relative to RPM.

Graphical data from above.

6 Diagnostic checking and equipment. Diagnostic measurements: oil pressure gauge,compression gauge, cylinder leakage tester, powerbalance tester, cooling system pressure tester.

Checking firing voltages.

7 Consideration of manufacturers’ dataagainst gathered data.

Effects of diagnostic measurements outwithmanufacturers’ tolerances.

Effects of combustion faults.

The effect of inaccurate service adjustments.

8 Engine service adjustments. Ignition, valve and injection timing.

Air/fuel ratio adjustment.

9 Control. Variable valve timing: its operation and effect.

Programmed control of ignition timing.




SUMMARY OF COURSE CONTENTSecondary/Chassis Systems (H)This unit covers transmission, brakes, steering and suspension. The transmission element includes aconsideration of the main system components and the power flow through these components, with theeffect of gearing upon transmitted power being considered by investigation and calculation. Vehiclebraking is approached initially from the main system components, followed by consideration of thefactors which affect braking efficiency. In addition, measurement of brake balance and efficiency areundertaken as a practical exercise. The relationship of force, pressure and area is also considered andcalculated. The suspension system, like the other areas, is initially approached by considering themain system components. This is followed by investigating the components involved in the control ofbounce, pitch and roll. Hooke’s law is applied by experiment, and the way energy is stored anddissipated is considered. Finally, the steering system is considered in terms of main components andthe application of the Ackerman principle of steering. Consideration of castor, camber, KPI (king pininclination), toe out on turns and true rolling motion is included, with investigation of these anglesbeing made on the vehicle.

As part of the extended study and integration the following areas will be considered: a matchingexercise of transmission types to engine characteristics, anti-locking brakes providing an additionalarea of investigation and integration for the braking system with electronic control, and the specialconsiderations needed when incorporating ABS (anti-lock braking system) within a vehicleemploying four-wheel drive (4WD). The effect and control of a shift in a vehicle’s centre of gravitywill be considered.

CONTENT STATEMENTSSecondary/Chassis Systems (H)The content statements given in the left-hand column of the table below describe in detail what thecandidate should be able to do in demonstrating knowledge and understanding.



1 Transmission system layouts. Front-wheel drive, rear-wheel drive, four-wheeldrive systems.

Component names and functions.

2 Power flow and gear ratios. Tracing power from engine to road wheels.

Alterations in power, torque and speed.

Calculation of gear ratios.

Overall gear ratios from engine to road wheels.

Matching engine characteristics to transmissiontrains.





3 Suspension system control. Bounce, pitch and roll.

Dampers, anti-roll bars, interlinked systems.

Panhard rods, spring rate.

4 Energy storage and dissipation. Measurement of spring deflection.

Energy conversion.

5 Electronic control of suspension. Active suspension systems.

6 Steering geometry and effect(including measurement).

Castor, camber, KPI, toe-out on turns, tracking,including measurement (Ackerman principle-concept only).

7 Body movement. Effect on steering angles and handling.

8 Brake efficiency and balance. Consideration of factors.

Measurement of efficiency and balance.

9 Brake control. Mechanical pressure control.

Weight transfer.

Anti-lock brake operation.

ABS four-wheel drive (concept only).




SUMMARY OF COURSE CONTENTVehicle Management Systems (H)This unit deals with modern vehicle electronic management systems by considering a range ofsensors employed in the measuring of physical conditions around the vehicle and by investigatinghow these sensors produce their signal. This is followed by consideration of the range of actuatorsemployed within the steering, brakes, transmission, suspension and engine systems, looking at theirfunctions and the role they play. The electronic control unit is introduced first by the candidatedrawing and naming the various elements of the control unit, and then differences between analogueand digital signals are considered. This leads to an understanding of how information is stored,compared and processed, and finally how the outputs are arrived at. In addition the candidate willconsider how information is represented in 3D maps. This knowledge is then applied for anelectronically controlled system, followed by a practical investigation involving the measurement ofsignals around the system using a range of measurement and diagnostic equipment. The candidatewill also be expected to explain the operation of the system being considered.

The unit also allows for integration and expansion of material, including how signals are convertedfrom analogue to digital and from digital to analogue, extraction of information carried withinsignals, and determination of faults in signals and how these may affect the operation of the system.The function of the microprocessor will be considered in relation to one of the vehicle systemsalready investigated. In addition the concept of open and closed loop control will be dealt with andthe effect of feedback on system operation considered. Finally, an understanding of the operation of asensor will be investigated, from measuring the physical condition within one of the vehicle systemsto how this condition is converted into a voltage.

CONTENT STATEMENTSVehicle Management Systems (H)The content statements given in the left-hand column of the table below describe in detail what thecandidate should be able to do in demonstrating knowledge and understanding.



1 Sensors. Temperature, pressure, position, speed, vibrationand oxygen sensors.

2 Actuators. Valves, motors and solenoids.

3 Control. General processor signal conversion, analogue,digital, binary code, processor communication,memory and logic circuits.

4 Measurement. Sample signals to and from ECU (electronic controlunit), use of multimeters, oscilloscopes anddedicated diagnostic equipment.




ASSESSMENT

To gain the award of the course, the candidate must pass all the unit assessments as well as the externalassessment. External assessment will provide the basis for grading attainment in the course award.

When the units are taken as component parts of a course, candidates will have the opportunity toachieve a level beyond that required to attain each of the unit outcomes. This attainment may, whereappropriate, be recorded and used to contribute towards course estimates, and to provide evidence forappeals. Additional details are provided, where appropriate, with the exemplar assessment materials.Further information on the key principles of assessment is provided in the paper Assessment, (HSDU,1996) and in Managing Assessment (HSDU, 1998).

DETAILS OF THE INSTRUMENTS FOR EXTERNAL ASSESSMENT

The external assessment will comprise a written examination paper. The time allocation for thequestion paper will be three hours: the paper will sample across all the individual course units. Thequestions will measure the candidates’ ability to apply their knowledge in new or varied contexts.The paper will be worth 100 marks. Candidates should attempt all questions.

The questions will assess the candidate’s ability to demonstrate skills which show knowledge andunderstanding across all the component units. The candidate will be required to calculate, providewritten answers to set questions and draw graphical representations of systems.

The paper will include a number of questions which will allow the candidate to demonstrate extendedknowledge.

GRADE DESCRIPTIONS

The grade of award A, B or C will be based on the total score obtained in the examination paper. Thedescriptions overleaf indicate the nature of the achievement which is required for the award of agrade C and grade A in the course assessment. They are intended to assist candidates,teachers/lecturers and users of the certificate and to help establish standards when question papers arebeing set.




GRADE C GRADE A

The candidate provides a description of theeffects of gearing upon engine power andcalculates the effect on torque and rotationalspeed.

In addition the candidate should provide anexplanation of how a particular transmissionsystem can complement particular enginecharacteristics.

A description of the factors which determinebraking efficiency and balance is provided. Inaddition, an explanation of how brake force iscontrolled by both mechanical and ABS systemsis included.

In addition the candidate should provide anexplanation of the operation of ABS and adescription of how the electronically controlledsystem more accurately limits brake forcerelative to dynamic conditions.

The candidate provides a description of howvehicle body attitude is controlled with respect topermanent mechanical/hydraulic systems anddescribes the effect of vehicle body movementupon steering angles.

In addition to the operational effects ofmechanical/hydraulic components and systems inthe control of body movement and the effectsupon steering angles, the candidate includes adescription of the incorporation of electronicallyoperated interactive suspension systems inlimiting the effects upon body movement, anddescribes the effect of body movement uponvehicle handling.

The candidate demonstrates understanding ofengine operation service adjustments toefficiency, emissions and performance.

The candidate demonstrates understanding of theeffects of service adjustments on maintainingengine efficiency, emissions and performance,with the addition of the use of electronic andprogrammed control upon these factors.

When considering engine characteristics, adescription of power and torque delivered withrespect to RPM is detailed, and a comparison ofdata provided is made by the candidate.

In addition the candidate will also explain howthese characteristics manifest themselves relativeto the vehicle performance on the road.

The candidate provides an explanation of howsensors measure physical conditions and howthese signals are handled by the ECU in basicterms of matching input information with thestored data, and finally how the resulting outputsignal adjusts system conditions.

In addition the candidate should provide moredetail of how signals are employed within theECU, with a description of how new informationis matched with stored data. The candidateshould also provide details specific to a systemand explain how a closed-loop arrangement canaffect system operation, with a clear descriptionof the benefits to system efficiency.




APPROACHES TO LEARNING AND TEACHING

The delivery of the units should be integrated to fulfil the rationale and provide the benefits ofundertaking a course. This may be best achieved by relating Vehicle Management Systems (H) tothe two other units. It is not possible to integrate all outcomes because of the diversity of thecontent involved. However, within Internal Combustion Heat Engines (H) the concepts of efficiency,performance and emission control would provide integration across the outcomes. In addition, theconcept of performance allows matching of transmission trains to engine characteristics to be aconcept which links engines and chassis systems. Within Secondary/Chassis Systems (H) the conceptof vehicle handling in terms of control and shift in the vehicle’s centre of gravity would provide anintegrated approach to studying steering, suspension and braking systems. The delivery should reflectthe course rationale, concept and content.

A variety of learning and teaching approaches should be used to sustain interest and have maximumeffect on learning. Extensive use should be made of participative methods which help to developcandidates’ independent thinking and communication skills. Small-group work should be used topromote teamwork and develop interpersonal skills. Practical investigations should be usedextensively to develop inquiry skills and attitudes.

Consolidation of the subject matter can be achieved by the type of integration highlighted aboveapplied in various contexts by utilising part of the additional 40 hours available as part of the course.

Preparatory work for the external course assessment can be achieved by providing the candidateswith exercises which allow them to utilise existing knowledge and apply this knowledge in unfamiliarcontexts. These exercises could be constructed in a way which allows some candidates theopportunity for consolidation of their subject knowledge, while at the same time providing otherswith the opportunity to prepare for grades in the external course assessment above Grade C.

SPECIAL NEEDS

This course specification is intended to ensure that there are no artificial barriers to learning orassessment. Special needs of individual candidates should be taken into account when planninglearning experiences, selecting assessment instruments or considering alternative outcomes for units.For information on these, please refer to the SQA document Guidance on Special Assessment andCertification Arrangements for Candidates with Special Needs/Candidates whose First Language isnot English (SQA, 1998).




SUBJECT GUIDES

A Subject Guide to accompany the Arrangements documents has been produced by the Higher StillDevelopment Unit (HSDU) in partnership with the Scottish Consultative Council on the Curriculum(SCCC) and Scottish Further Education Unit (SFEU). The Guide provides further advice andinformation about:

• support materials for each course• learning and teaching approaches in addition to the information provided in the Arrangements

document• assessment• ensuring appropriate access for candidates with special educational needs

The Subject Guide is intended to support the information contained in the Arrangements document.The SQA Arrangements documents contain the standards against which candidates are assessed.


Superclass: XS

Publication date: December 1999


Version: 03



Additional copies of this unit specification can be purchased from the Scottish Qualifications Authority. The cost for eachunit specification is £2.50 (minimum order £5).

14

National Unit Specification: general information

UNIT Internal Combustion Heat Engines (Higher)

NUMBER D153 12


SUMMARY

This unit provides the candidate with a comprehensive study of internal combustion engines from thestandpoint of cycle of operation, cylinder arrangements, firing orders and engine adjustments.

It does not deal with engine construction detail but considers a comparison of engine types. Thecombustion processes of both SI and CI engines are investigated, and combustion faults, cause andeffect considered. This allows the candidate to consider engine settings and their effect on emissions,power and economy.

The candidate moves on from this to consider and produce graphs from given dynamometer readoutsand also perform engine condition checks. This provides the candidate with a method of determiningengine condition. This could be related to the effect that engine condition will have on engineoutputs.

OUTCOMES

1 Compare SI and CI internal combustion engines in terms of the operating cycles and outputcharacteristics.

2 Explain the combustion process of SI and CI internal combustion engines.3 Carry out engine input/output measurements and diagnostic checks.4 Perform checks and adjustments to engine systems.

Automotive Engineering – Unit Specification: Internal Combustion Heat Engines (H) 15

National Unit Specification: general information (cont)


RECOMMENDED ENTRY




CREDIT VALUE

1 credit at Higher.

CORE SKILLS

This unit gives automatic certification of the following:

Complete core skills for the unit None

Additional core skills components for the unit Critical Thinking Int 2



National Unit Specification: statement of standards


Acceptable performance in this unit will be the satisfactory achievement of the standards set out inthis part of the unit specification. All sections of the statement of standards are mandatory and cannotbe altered without reference to the Scottish Qualifications Authority.

OUTCOME 1

Compare SI and CI internal combustion engines in terms of the operating cycles and outputcharacteristics.

Performance criteria(a) Description of the cycle of engine operation for 2 and 4 stroke SI and CI engines and rotary SI

engines is accurate and comprehensive.(b) Comparisons of the use of various types of engine are made and valid conclusions are drawn in

terms of output characteristics and application.

Note on range for the outcomeEngine terms: SI, CI, stroke, bore, firing point, swept volume, clearance volume, TDC, BDC, CC,compression ratio, torque, power, RPM, firing order.Engine operation: to include firing point and valve/port timing.

Evidence requirementsWritten and graphical evidence of the candidate’s ability to compare and define engine operatingcharacteristics and sequences.

OUTCOME 2

Explain the combustion processes of SI and CI internal combustion engines.

Performance criteria(a) The combustion process of an SI engine is described fully and accurately.(b) The combustion process of a CI engine is described fully and accurately.(c) The cause and effect of three combustion faults for both SI and CI engines are explained

clearly, systematically and accurately.

Evidence requirementsWritten evidence that the candidate is able to demonstrate the ability to describe the normalcombustion processes for both SI and CI engines. Written evidence is also required of the candidate’sability to explain the causes and effects of combustion faults.


National Unit Specification: statement of standards (cont)


OUTCOME 3

Carry out engine input/output measurements and diagnostic checks.

Performance criteria(a) Engine diagnostic measurements are recorded and interpreted accurately and in accordance

with manufacturers’ recommendations.(b) Engine input/output characteristics from a given dynamometer readout are recorded and

interpreted accurately.(c) A graph of engine output characteristics is produced and interpreted correctly.

Note on range for the outcomeDiagnostic measurements: oil pressure test, compression test, cylinder leakage test, power balancetest, cooling system pressure test.

Evidence requirementsWritten and graphical evidence of the candidate’s ability to record and interpret input/outputmeasurement and diagnostic checks.

OUTCOME 4

Perform checks and adjustments to engine systems.

Performance criteria(a) Readings from an exhaust gas analyser are accurately recorded and air/fuel ratio adjusted

appropriately.(b) Valve clearances and valve timing are checked systematically and adjusted in accordance with

manufacturers’ recommendations.(c) Ignition timing and firing voltages are checked systematically and adjusted according to

manufacturers’ recommendations.(d) CI engine injection timing is checked systematically and adjusted according to manufacturers’

recommendations.

Note on range for the outcomeFour-gas analyser applied to catalytic and non-catalytic engines, ignition timing, electronic systemsonly.

Evidence requirementsEvidence of actual performance of the candidate which demonstrates their ability to carry out checksand adjustments to subsystems and measure emission outputs. Written evidence is also required ofreadings from an exhaust gas analyser for PC (a).


National Unit Specification: support notes


This part of the unit specification is offered as guidance. The support notes are not mandatory.

It is recommended that you refer to the SQA Arrangements document for Higher AutomotiveEngineering before delivering this unit.

While the time allocated to this unit is at the discretion of the centre, the notional design length is 40 hours.

The purpose of this unit is to develop an understanding of internal combustion engine operation andthe candidate’s ability to compare different types and recognise the use of each type. Theunderstanding should include the combustion processes and the importance of accurate engineadjustments to maintaining efficient operation. It should also include the ability to performadjustments and checks to engines and subsystems.

GUIDANCE ON CONTENT AND CONTEXT FOR THIS UNIT

The delivery suggestions for each outcome describe teaching approaches that may be employed andmake reference to taught material which may form the basis of content for the external assessment.

Outcome 1Included should be engine types differing in cycle of operation, cylinder arrangement and number ofcylinders, engine application, reasons for application, advantages and disadvantages associated witheach type and arrangement. Rotary arrangements should also be covered. Engine terminology shouldbe clearly explained for each application.

Outcome 2Energy release on the combustion of the fuel and the normal combustion process of both petrol anddiesel fuels should be explained. The effects of burning fuels, in terms of both energy released andwaste products, should be explained. Finally, combustion faults for both SI and CI engines should bediscussed, providing a clear picture of the effects of each fault.

Outcome 3Take essential measurements to ascertain engine condition and test engine outputs in terms of powerand torque relative to engine RPM using dynamometer readings.

Outcome 4Employ manufacturers’ data to check and adjust engine systems and components to maintainoptimum performance. This may include valve timing adjustment, valve clearances, ignition timingand fuel pump timing.


National Unit Specification: support notes (cont)


GUIDANCE ON LEARNING AND TEACHING APPROACHES FOR THIS UNIT

Outcome 1Videos, slides, drawings and actual engine units may be the most appropriate aids to explainingengine terms, types and arrangements. Comparisons of engine types employed in differing situations,using manufacturer’s data relative to each engine’s outputs, would provide a comparative study.Incorporating emissions of noise and pollutants should be an additional consideration.

Outcome 2Videos, slides and cylinder heads showing combustion chamber design could be used to aid candidateunderstanding of fuel combustion. In addition, damaged components may prove a worthwhile visualaid to highlighting possible damage due to combustion faults. The importance of service adjustmentsin aiding correct combustion processes and the effects on emission could provide an opportunity forthe candidate to gain knowledge and understanding in preparation for the external assessment of theHigher Automotive Engineering.

Outcome 3Delivery is best suited to a workshop environment where internal combustion engines, both SI and CI, areavailable. Demonstration of measurements and engine adjustments are carried out, followed by candidateparticipation. A dynamometer could be employed in order that engine outputs can be measured.

Study of the effects, either measured or anticipated, of the use of variable valve timing upon engineefficiency might appear in the external assessment of the Higher Automotive Engineering.

Outcome 4A practical setting is essential for the teaching of this outcome. A range of internal combustionengines should be available, with accompanying manufacturers’ data, to aid accurate engineadjustments. Teacher/lecturer demonstration should be followed by candidate practice of alladjustments. A lecture on modern engine controls, which reduce the need for service adjustments,should be used to provide additional material.

Note: references to the Higher are intended for candidates whose aim is to achieve the course inaddition to achieving this particular unit.

GUIDANCE ON APPROACHES TO ASSESSMENT FOR THIS UNIT

Examples of instruments of assessment corresponding to Outcomes 1-4 are as follows:

Outcome 1• extended response question to evaluate the understanding of engine cycles and the

incorporation of engine terms• graphical exercise to compare operating characteristics of various given engine types


National Course Specification: support notes (cont)


Outcome 2• extended response question to test the understanding of normal combustion processes of SI and

CI engines• extended response question supported by graphics to demonstrate an understanding of common

combustion faults

Outcome 3• practical exercise incorporating engine diagnostic and output measurements and recording of data• practical exercise to record readings from exhaust output

A dynamometer could be employed in order that engine outputs can be measured.

Outcome 4• practical exercise which measures the candidate’s ability to perform subsystem checks and

adjustments to ignition, valve and CI fuel systems

In general, the approach should be to develop the candidate’s awareness and understanding ofmodern vehicle technology, how the varying systems interact and how electronic control plays anever-increasing role. Evidence that this has been achieved can be gained from the employment ofpractical exercises incorporating detailed worksheets in addition to structured questions. During suchexercises the candidate could be given the opportunity to demonstrate ability beyond therequirements of the unit assessment if achievement of the Higher Automotive Engineering course aswell as the unit was the aim.

SPECIAL NEEDS

This unit specification is intended to ensure that there are no artificial barriers to learning orassessment. Special needs of individual candidates should be taken into account when planninglearning experiences, selecting assessment instruments or considering alternative outcomes for units.For information on these, please refer to the SQA document Guidance on Special Assessment andCertification Arrangements for Candidates with Special Needs/Candidates whose First Language isnot English (SQA, 1998).


Superclass: XS

Publication date: February 2001


Version: 03




21


UNIT Secondary/Chassis Systems (Higher)

NUMBER D154 12


SUMMARY

This unit provides the candidate with an understanding of transmission, brakes, steering andsuspension. The transmission element includes a consideration of the main system components andthe power flow through these components, with the effect of gearing upon transmitted power beingconsidered by investigation and calculation. Vehicle braking is approached initially from the mainsystem components, followed by consideration of the factors which affect braking efficiency. Inaddition, measurement of brake balance and efficiency are undertaken as a practical exercise. Therelationship of force, pressure and area is also considered and calculated. The suspension system, likethe other areas, is initially approached by considering the main system components. This is followedby investigating the components involved in the control of bounce, pitch and roll. Hooke’s law isapplied by experiment, and the way energy is stored and dissipated is considered. Finally, the steeringsystem is considered in terms of main components and the application of the Ackerman principle ofsteering. Consideration of castor, camber, KPI (king pin inclination), toe out on turns and true rollingmotion is included, with investigation of these angles being made on the vehicle.

OUTCOMES

1 Describe the function of the secondary/chassis systems and the interaction of the main systemcomponents.

2 Investigate secondary/chassis systems by conducting measurement and calculation exercises.3 Explain the control required of the secondary/chassis systems, relative to the vehicle dynamics.

Automotive Engineering – Unit Specification: Secondary/Chassis Systems (H) 22



RECOMMENDED ENTRY




CREDIT VALUE

1 credit at Higher.

CORE SKILLS

There is no automatic certification of core skills or core skills components in this unit.






OUTCOME 1

Describe the function of the secondary/chassis systems and the interaction of the main systemcomponents.

Performance criteria(a) Function of the main chassis systems and components is explained clearly, accurately and

comprehensively.(b) Gear ratios are determined accurately and the resulting effect upon power transmitted is stated

clearly and correctly.(c) Reasons why suspension systems control bounce, pitch and roll are clearly and correctly

explained.(d) Effects of castor, camber, KPI and the Ackerman principle of steering are clearly, accurately

and comprehensively described.(e) Key factors which contribute to brake efficiency are clearly, accurately and comprehensively

explained.

Note on range for the outcomeMain system and components of the steering, suspension, brake and transmission systems.

Evidence requirementsWritten and/or oral evidence is required of the candidate’s ability to describe the function andinteraction of secondary/chassis systems.

OUTCOME 2

Investigate secondary/chassis systems by conducting measurement and calculation exercises.

Performance criteria(a) Overall gear ratios are calculated accurately.(b) Hooke’s law is accurately and fully explained and spring deflection measured correctly and

accurately.(c) Steering angles including castor, camber, KPI, toe out on turns and tracking are measured

correctly and accurately.(d) Brake efficiency and brake balance are measured correctly and accurately.

Evidence requirementsEvidence of actual performance which demonstrates the candidate’s ability to carry outmeasurements to investigate secondary/chassis systems. Written evidence of calculations and systemsettings is also required.




OUTCOME 3

Explain the control required of the secondary/chassis systems, relative to the vehicle dynamics.

Performance criteria(a) A range of gear ratios is selected which complements effectively the given engine

characteristics.(b) Reasons why a shift in the centre of gravity of a vehicle will affect steering angles and vehicle

handling are explained clearly and accurately.(c) Ways in which a braking system can control brake force relative to weight transfer are

explained clearly, correctly and comprehensively.(d) Ways in which a suspension system can control the shift in a vehicle’s centre of gravity are

determined and explained clearly and correctly.

Evidence requirementsWritten and/or oral evidence of the candidate’s ability to explain the control required of thesecondary chassis systems relative to the vehicle dynamics.







On completion of this unit the candidate should have developed an understanding of the control ofthe dynamics associated with secondary/chassis systems and how this control affects the operation ofthe systems. In addition, the candidate will develop an awareness of the need to match specific enginecharacteristics to specific transmission trains.


The candidate should achieve an understanding of how the movement of the centre of gravity of avehicle needs to be controlled in order to maintain effective overall vehicle handling. The studybegins with non-electronically controlled methods of maintaining correct vehicle attitude in order todevelop the concepts involved. Candidates can then progress to the incorporation of electronic control inlimiting the shift in centre of gravity. The candidate should also investigate the effects of change invehicle attitude on the operation of the braking and steering systems. These considerations can beevolved by the use of actual vehicles and/or systems and by the use of video and software support.

Outcome 1Introduction to the main components of the secondary/chassis systems and the interaction of thesecomponents and systems. The candidate will consider the general functions of the systems, anddevelop this to consider the systems in more detail.

The transmission will be considered by investigating the effect of gearing upon engine power, andhow torque and RPM are altered. The steering system will be considered by looking into the effect ofvarious steering angles and the role they play in overall vehicle handling. The suspension system willbe investigated by considering the ways in which body movement is controlled and the need for suchcontrol. Finally, the braking system will involve considering the contributing factors to brakingefficiency and brake balance. The coefficient of friction and the principles of friction and therelationship between force, pressure and area should also be included.

Introduction to the braking system and description of location and explanation of the function ofsystem components should be included. All the factors which affect braking efficiency should beconsidered and explained clearly. The common factors affecting braking efficiency should beexplored and the measurement of brake balance and efficiency carried out.

Outcome 2The candidate will study the same systems by measuring steering angles and by measuring brakebalance and efficiency. The principle of Hooke’s law will be investigated by experiment supported byteacher/lecturer explanation to provide the candidate with an understanding of how spring materialsbehave. Candidates will study the transmission system by calculating overall gear ratios and relatingthese calculations to earlier understanding.




Outcome 3The concept of control relative to body movement and the effects of body movement upon vehiclehandling will be considered. The need for the control of braking forces and force distribution aroundthe vehicle will be investigated relative to a shift in the vehicle’s centre of gravity. The concept ofelectronic control applied to suspension and braking systems affords the candidate the opportunity toinvestigate how overall control is achieved.

Steering angles should be considered during cornering, braking and acceleration. Brake controlshould be considered in terms of mechanical/hydraulic systems only. Control of body movementshould be limited to mechanical and hydraulic/gas methods only.


It would be advantageous to have access to a workshop environment and vehicles to aid the deliveryof this unit.

Outcome 1A workshop setting with vehicles would assist in the location of system components and their relativepositions to each other. Also, a range of components with sectional views can be employed to aidunderstanding of component function. When introducing the concept of gearing being employed tovary power delivered by the engine in terms of torque and speed, it would be helpful to use apractical experiential approach. This can be achieved by the use of a transmission train and/orgearboxes and final drive units as part of a candidate experiment. Increasingly complex and fulldiagrams representing gear trains could be employed, along with a transmission system, to aid theunderstanding of the power flow and the effects upon power at each stage in the transmission system.Vehicles can be used to investigate the arrangement of steering, suspension and braking systems, withvideo, graphics, manufacturers’ data and computer interactive software being utilised to aid candidateunderstanding. A practical observation of brake efficiency and balance tests can be employed,followed by a lecture and discussion on the contributing factors to efficiency and by experimentsinvolving friction and heat being utilised.

Outcome 2This outcome should be approached by employing a hands-on approach, the main aim being to allowthe candidate the opportunity to work with the systems being investigated by applying measurementtechniques and calculation to enhance understanding. The teaching of this outcome may be bestapproached by integrating it within Outcome 1, thus allowing the candidates to work with thesystems as they are considering system functions.

Outcome 3This outcome is concerned with control and the effect of vehicle dynamics upon the brakes, steering and suspension systems as well as the consideration of the characteristics of engine output and the most appropriate match of transmission system to provide economy and performance. The candidate will be provided with choices of engines and transmissions from which he or she will select the most appropriate match. The teacher/lecturer will provide explanations as to the factors to be considered in making a selection. Suspensions will be considered by looking at the ways in which they can control or limit body movement, starting from mechanical control systems and progressing on to




explanations of electronic control. Body movement can be utilised to explain the effects of bodymovement on steering angles and vehicle handling. The braking system will also be consideredrelative to body movement and the need to distribute and control brake force relative to thismovement. The introduction of ABS can be incorporated into the control and can utilise conceptstaught within the unit Vehicle Management Systems (H).


Examples of instruments of assessment that could be used are as follows.

Outcome 1• short-answer question paper which allows the candidate to define the function of the secondary

chassis systems and the terms castor, camber, KPI in addition to how the suspension systemcontrols bounce, pitch and roll

• practical exercise incorporating a short-answer question paper to allow candidates theopportunity to demonstrate their understanding of the effect of gearing

• oral questioning of the candidates to determine the factors which affect braking efficiency

Outcome 2• numerical exercise to evaluate the candidate’s ability to calculate overall gear ratios• practical exercise to prove Hooke’s law and measure steering angles• practical exercise to measure brake balance and efficiency and record results

Outcome 3• graphical exercise to compare transmission and engine characteristics and select an appropriate

match• extended response question paper where the candidate explains the effect of vehicle body

movement on the braking, steering and suspension systems

The delivery of this unit is concerned with initial concepts, followed by investigating the systems byapplying practical measurement and finally considering the need and effect of control, both manualand electronic. Assessment evidence can be gathered initially through appropriate factual questions,practical experiment and finally by analysis and explanation concerning the need and operation ofsuspension and braking system control methods. This final aspect can be incorporated withassessment procedures applied to the unit Vehicle Management Systems (H) in the HigherAutomotive Engineering course.

SPECIAL NEEDS



Superclass: XS

Publication date: December 1999


Version: 03




28


UNIT Vehicle Management Systems (Higher)

NUMBER D155 12


SUMMARY

This unit would be useful to candidates who require an understanding of vehicle electronic controlsystems and wish to undertake measurement of system components.

This unit is designed to provide the candidate with a knowledge of modern vehicle electronicsystems. The candidate will investigate the different sensors employed to measure a range of physicalconditions allied to various systems. The investigation will continue with the candidate studying thevarious actuators incorporated in vehicle systems and the candidate will be led to an understanding ofthe function of electronic control units. Following from this the candidate will apply this knowledgeto a particular electronic system and will use diagnostic equipment on this system.

OUTCOMES

1 Explain the relationship and operation of sensors employed in vehicle systems with referenceto the physical conditions they measure.

2 Identify and explain the function and operation of actuators employed in modern vehicleapplications.

3 Demonstrate an understanding of the signal processing undertaken by the electronic controlunit.

4 Use diagnostic equipment to record readings from a stated electronic vehicle system inaccordance with manufacturers’ procedures.

Automotive Engineering – Unit Specification: Vehicle Management Systems (H) 29



RECOMMENDED ENTRY




CREDIT VALUE

1 credit at Higher.

CORE SKILLS

There is no automatic certification of core skills or core skills components in this unit.






OUTCOME 1

Explain the relationship and operation of sensors employed in vehicle systems with reference to thephysical conditions they measure.

Performance criteria(a) A range of sensors used in vehicle management systems is accurately identified.(b) Output signals from a range of sensors used in vehicle management systems are clearly and

accurately drawn.(c) An explanation of how signals are produced by a range of sensors used in vehicle management

systems is clear, correct and comprehensive.

Note on range for the outcomeRange of sensors used in vehicle management systems: speed and position, pressure, temperature,engine knock, exhaust emissions, fluid levels.

Evidence requirementsGraphical and written evidence of the explanation of the relationship and operation of electronicsensors and the physical conditions they represent.

OUTCOME 2

Identify and explain the function and operation of actuators employed in modern vehicle applications.

Performance criteria(a) The functions of a range of actuators employed in the adjustment of settings of vehicle

management systems are clearly and accurately explained.(b) The operations of a range of actuators employed in the adjustment of settings of vehicle

management systems are clearly and accurately explained.

Note on range for the outcomeActuators to include: linear and stepper motors and solenoids.

Evidence requirementsWritten evidence of the candidate’s ability to identify and explain the function and operation ofactuators employed in adjusting vehicle system settings as part of electronic control.




OUTCOME 3

Demonstrate an understanding of the signal processing undertaken by the electronic control unit.

Performance criteria(a) The difference between analogue and digital signals is clearly and correctly explained.(b) The way data is stored, compared and processed within the electronic control unit is correctly

identified.(c) Information from a three-dimensional map is read accurately.(d) A block diagram of the main components employed within the electronic control unit showing

the communication links between them is clearly and accurately set down.(e) The inputs and outputs to and from the electronic control unit for a given system are clearly

and accurately identified.

Evidence requirementsWritten and graphical evidence of the candidate’s ability to explain the operation of memory systemsand handling of data, and how the central processing unit communicates with memory, inputs, andoutput stages.

OUTCOME 4

Use diagnostic equipment to record readings from a stated electronic vehicle system in accordancewith manufacturers’ procedures.

Performance criteria(a) An understanding of sensors and actuators employed in a named system and how they effect

system operation is clearly and correctly demonstrated.(b) Diagnostic equipment is used accurately and effectively to record readings from system

sensors.(c) An oscilloscope is used to view signals generated by named sensors accurately and effectively.(d) Diagnostic equipment is used to record readings transmitted by the ECU to system actuators

accurately and effectively.

Evidence requirementsWritten and/or oral evidence of the candidate’s ability to explain the use of sensors and actuatorsemployed in a selected vehicle system. A check sheet may be used to monitor and record the practicalactivities.







This unit will provide the candidate with an understanding of the operation of electronic controlsystems and methods of sensing, comparing, evaluating and altering settings to maintain effective andefficient system and vehicle operation. Many of the aspects considered can be of equal value in otherengineering disciplines where electronic control is employed.


Outcome 1Introduction to the various physical conditions must be considered relative to the various vehiclesystems, explanation given of the range of sensors, which accurately convert these physicalconditions into electrical signals, and basic detail of the way in which each sensor converts thephysical conditions. It is not expected that the candidate should understand in detail the electronicworkings of each sensor, but a realisation should be achieved that the sensor can convert quantitiesbeing measured into an appropriate set of information which can be interpreted by the ECU.

Outcome 2The candidate is expected to investigate a range of ECU-controlled actuators employed in varioustypes of system, to include transmission, brakes, steering/suspension and engine systems. Theactuators should be investigated and considered with respect to the signals they receive from the ECUand the operation and effect upon the system. Outcome 4 provides the candidate with a completesystem approach to considering the role of various actuators from the sensor signal to the commandtransmitted relative to this by the ECU.

Outcome 3Consideration of the basic function of the ECU should be introduced with respect to signalprocessing, memory matching and commands transmitted. The candidate should be introduced to theconcept of digital signals. The contents of the ECU should be considered as a block diagram with thelines of communication between the various parts highlighted. It would be useful if a signal generatedby a sensor was considered in terms of how it is processed and the resultant command arrived at.Three dimensional maps should be considered by explaining how information is stored andcompared.

Outcome 4This outcome provides the candidate with the opportunity to consider a complete electronic vehiclemanagement system, which should allow for integrating the various stages associated in the controlof that system. In addition the candidate will have the opportunity to locate the various componentsof a system and record readings at points around the system. Manufacturers’ data and proceduresshould be referred to during these measurements. It would be useful to incorporate the use ofoscilloscopes at this stage in order that appropriate signal patterns can be observed and compared.





It would be highly desirable to have access to modern vehicles and components and at least onededicated piece of diagnostic hardware associated with one of the systems being investigated. Inaddition, various interactive computer software programs could usefully be employed to aidcandidate comprehension.

Outcome 1Electronic kits employing a range of sensors that measure the range of physical quantities associatedwith vehicle systems could be used to aid candidate understanding. Experiments incorporating suchkits could be used in addition to videos and interactive computer software to allow candidates theopportunity of self-directed investigation. At least one live system should be available in order thatactual sensors can be investigated and, in association with Outcome 4, signals observed. Anexplanation of the need for the various sensors should be included and the importance of their signalsto the correct operation of the system as a whole explained.

This should provide the candidate with the opportunity to investigate how signals are converted fromanalogue to digital and digital to analogue. The candidate should also be able to extract informationfrom a variety of signals, be able to determine faults in shown signals, and explain the effect of thesefaulty signals on the system operation.

Outcome 2Outcome 2 should be like Outcome 1. It would be beneficial to point out that the actuators operate ata slower rate than the sensors or control, and thus, changing physical parameters observed by thesensors may not provide instant correction. Investigation of actuators which provide a variableadjustment to system settings, such as stepper motors, may provide an area for additionalconsideration.

Outcome 3This will perhaps be the most difficult area for the candidates to appreciate in full, and may require astep-by-step approach to delivery. The main concentration of input should relate to how signals arereceived, how they are interpreted and matched with memory, and finally how the output is arrived at.A simple approach employing basic electronic memory circuits with limited input/output parametersmay aid understanding. In addition, a basic explanation of the conversion of analogue to digital anddigital to analogue signals, may aid comprehension. Video and interactive computer software willalso be valuable in simplifying a complex subject. The electronic control unit can be consideredrelative to one of the systems already investigated. This consideration could include how theprocessor uses sensor information to adjust system settings.

Outcome 4This outcome will require at least one modern vehicle or vehicle system to allow a ‘hands-on’approach. In addition, interactive computer software would prove a valuable tool, allowingcandidates the opportunity to practise taking readings on the computer screen and familiarisingthemselves with the systems prior to working with actual systems. Video and slides should beincorporated when describing system operation. Only one electronically controlled system need beconsidered in detail. This outcome should of course be linked to the preceding outcomes and wherepossible should be integrated with Outcomes 1, 2 and 3.




This outcome should allow the candidate to integrate all outcomes and concepts covered in acomplete system approach from sensor to actuator and the physical changes to the system beingcontrolled.


Centres may use the instruments of assessment that they consider most appropriate.Examples of instruments of assessments that could be used are as follows:

Outcome 1• lists the range of physical conditions measured by sensors in vehicle management systems• graphical exercise to reproduce signals generated by the sensors employed within vehicle

management systems• extended response question where the candidate explains how physical conditions are

developed into electronic signals

Outcome 2• extended response question where the candidate explains the function of a range of actuators

and describes how each actuator adjusts the system operation relative to commands from theECU

Outcome 3• short response question requiring the candidate to describe the difference between analogue

and digital signals• extended response question where the candidate describes how data from sensors is compared

with data stored in memory and the resulting command arrived at• numerical exercise requiring the candidate to add and convert binary code into denary• graphical exercise where the candidate produces a table from a 3D memory map• graphical exercise requiring the candidate to produce a block diagram representing the main

sections and communication links within the ECU• graphical exercise where the candidate represents an electronically controlled system

indicating the inputs and potential outputs

Outcome 4• practical exercise where the candidate employs diagnostic and measuring equipment to monitor

and record readings from a electronically controlled system

In general, the approach should be one which requires the candidate to integrate knowledge and skillrelative to electronically controlled systems. The candidate will be expected to relate controloperation to inputs, processing and outputs. The candidate could be exposed to computer-generatedinteractive software as one means of assessing understanding. The use of actual systems should alsobe utilised as a medium for generating evidence.




SPECIAL NEEDS


automotive engineering higher · automotive engineering: higher course 1 note of changes to...

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