The subject presents and examines automotive fluid power components and systems in terms of their graphical symbols, layout, specific features, construction and operation. Students learn how to identify and interpret fluid power circuits, comprehend and explain their purpose in relation with their constitutive components. Aim of the subject is to acquaint students with methods for the analysis and critical evaluation of fluid power components and systems specific to automotive applications.

Foreword: aim of a fluid power system is to transfer power through a working fluid. In the automotive field, typical applications are steering units, breaking systems, active suspensions, variable valve actuation and much more. The design, development, testing and production of fluid power components or systems require very specific competencies, but the prerequisite is a strong and solid knowledge of the basic principles governing the generation and the control of the hydraulic power and the mutual interaction among the components. In this context, the knowledge acquired by the students upon completion of this subject involves: • to interpret a simple fluid power scheme according to the ISO standard 1219, • to identify the main fluid power components, their specific function and operation, • to know the fundamental equations for the evaluation of the flow rate, pressure, speed, torque and power, • to identify and quantify the sources of power dissipation in a fluid power system and evaluate the efficiency, • to learn the working principle of the main automotive fluid power systems and components, • to learn the basics of some commercial tools for the simulation of fluid power circuits. With the skills acquired during the course, students should be able to: • design a simple layout of a fluid power system, • select and size the correct component (pump, actuator, valve) to achieve a specified function, • analyse qualitatively and quantitatively the different working modes of a fluid power circuit, • understand the working principle of the following fluid power systems: - hydraulic steering units for passenger cars and off-road vehicles, - electrohydraulic breaking systems, - closed circuit hydrostatic transmissions, - lubricating circuits for internal combustion engines.

Awareness of basic concepts covered in Physics and Fluid Mechanics.

Main topics are the following: • Fundamentals of Fluid Power (8 hours). ISO standard 1219, fluid properties, functional blocks. • Positive displacement pumps and motors (8 hours): different designs, real steady-state characteristics flow-pressure and flow-speed, instantaneous flow rate and torque, volumetric and mechanical-hydraulic efficiencies, flow and torque losses models, evaluation of the displacement. Controls for displacement variation. • Fluid Power valves (6 hours): on-off directional control valves; flow and pressure control valves (pressure relief, pressure reducing, sequence, two-port and three-port flow control), single and double stage; ideal and real performance characteristics; analysis of real components. • Accumulators (1 hour): types and their dimensioning criteria. • Flow generating units (5 hours): constant and variable flow rate, for open and closed circuits; constant pressure; ideal and real performance characteristics. • Hydrostatic steering systems for passenger cars and off-road vehicles (8 hours): working principles, mechanical position feedback, analysis of sections of the rotary valves, fixed and variable displacement pumps. • Hydrostatic braking systems (7 hours): brake booster, vacuum pump, tandem master cylinder, ABS modules (from 2S to 8). The ESP integration for lateral stability. • Hydrostatic transmissions (4 hours): transmission ratio and torque ratio, characteristics of primary variable-secondary fixed, primary fixed-secondary variable, primary variable-secondary variable versions, total efficiency, corner power and torque conversion range. • Hydraulic valve train (1 hour): hydraulic lash adjusters, variable valve actuation. • ICE lubrication systems (6 hours): layout (wet and dry sump solutions), oil path and pressure distribution inside the crankshaft; journal bearings: pressure distribution (Sommerfeld and Ockvirk bearings), load capacity, through flow; cooling jets; fluid conditioning group; lubricating pumps, fixed and variable displacement, with discrete pressure controls; evaluation of the pressure and flow rate through the circuit as function of oil temperature and engine speed. Basic properties of the lubricants. • Lumped parameter simulation of fluid power components (6 hours).

The subject is made up of theoretical lectures (the attendance is highly recommended), applied lectures and laboratory sessions. In the applied lectures, some numerical exercises are solved with the assistance of the teacher and the components/circuits used for the laboratory experiences are explained. During the semester, five additional numerical exercises will be progressively proposed on the Didactic Web Portal of the Politecnico. This homework must be downloaded and solved individually, according to explicit rules, by all students. The purpose of the homework is twofold: a self-assessment of acquired knowledge and competence; a training route toward the final written test. When successfully registering the exam, students have to hand in the complete set of their own homework. Two mandatory sessions of laboratory work (1.5 hours each) are carried out at the Fluid Power Research Laboratory (Main Campus): • Pumps/motors and didactic test rig: various positive displacement pumps and motors (external and internal gear, axial and radial piston and vane machines) of different manufacturers are disassembled, analysed and contrasted to understand and appraise their peculiarities and mode of operation. Finally a simple hydraulic circuit is used on a didactic test rig. • Steering servo systems and electro-hydraulic braking systems: the main components are disassembled and analysed. Four mandatory sessions of simulation work (1.5 hours each) are carried out. Briefly introducing simulation environments (Simcentre Amesim and GT-SUITE), problems in modelling and simulation of simple components and systems are presented. Students have the opportunity to perform simulations to gain direct experience of the approach and gain perception of the involved potentials. A written report about the simulation experiences must be prepared and presented at the examination. Finally, students are invited (optional activity) to reproduce on their own some simple hydraulic circuits using the free Student Edition of Amesim; some examples of simulation are shown during the lectures.

In order to avoid students to print on their own the didactic material, the entire set of slides used during the semester in high quality B/W printed form will be available at the beginning of the didactic term: • Nervegna, Rundo: Automotive Fluid Power Systems, Epics Edizioni, Collana Politeko, Torino. ISBN 978-88-94802-06-1. New improved and corrected reprints are available yearly at the end of February. Moreover, blocks of slides (with possible minor updates) will be progressively made available only to enrolled students on the Didactic Web Portal in electronic and colour version at the end of the lectures. However students are strongly invited to integrate the material with their own notes. A glossary with the main Fluid Power terms will be also uploaded on the Web Portal. For additional insight into specific topics, reference is made to the following material (in Italian): • Nervegna: Oleodinamica e pneumatica: Sistemi. Vol. 1, Politeko, Torino • Nervegna: Oleodinamica e pneumatica: Componenti. Vol. 2, Politeko, Torino • Gilardino: Esercizi di Oleodinamica, Clut, Torino Some additional information (bibliography, links, animations) can be found on the official web site of the Fluid Power Laboratory (http://www.fprl.polito.it).

Modalità di esame: Prova orale obbligatoria; Prova orale facoltativa; Prova scritta su carta con videosorveglianza dei docenti;

GENERAL RULES VALID FOR BOTH ONLINE AND ONSITE EXAMS The aim of the exam is to assess the acquired knowledge and the skills listed in the section “Expected Learning Outcomes”. It is mandatory to book the exam on the didactic web portal; the booking must be cancelled if, for any reason, the student cannot (or no longer wish to) attend the exam. The final exam is made up of a written test and an oral test (optional or mandatory). The written exam is composed by two parts (1 hour each). The first part involves 5 numerical questions on a proposed problem (max 15 points). The progressive stages of all calculations must be shown: any formula used, how the numbers are substituted into the formula and the final result in the requested unit. The answer is considered fully correct only if the formula used and the result are both correct. The second part includes 2 theoretical multiple-choice questions (max 4 points) and 2 open-ended questions (max 11 points) on all concepts and principles exposed during the lectures and laboratory sessions. In multiple-choice questions (with three answers, only one correct), student must be able to demonstrate the knowledge of the basic concepts; 2 marks are assigned if the answer is correct, 0 marks for no answer, a penalty of 1 mark for incorrect answer. In the open-ended questions, candidates must be able to explain the working principle of a component or of a system, to discuss about advantages and drawbacks of different solutions, to derive analytic governing equations, to obtain the theoretical and real steady-state characteristics and to draw the basic hydraulic circuits using the correct standard symbols. The test is a “NO BOOK EXAM”: the use of personal notes, books and manuals in any form (hard copies and electronic versions) is strictly forbidden. Candidates can have on the desk only identity document, blank sheets, writing instruments and a scientific calculator. Mobile phones and other electronic devices must remain switched off throughout the test. Some examples of written tests with solutions will be available on the didactic web portal before the end of the course. The results of the written test will be published on the didactic web portal as soon as possible. For those who reach in the written test a mark in the range: • above 20/30, the oral examination is optional, • from 15/30 to 20/30, an additional oral examination is required to pass the exam, • below 15/30, the exam is failed. In case of withdrawal from the first or second part of the written test (it is possible at any time), the exam will be recorded as failed. Students who have potentially passed the exam (mark in the written test > 20/30) can retake the exam if not satisfied with the mark (the exam will be recorded as failed). In case of oral exam, the final mark will be the average between oral (max 30 points) and written (max 30 points) part. If the combined mark is < 18/30 the exam is failed and it will be necessary to retake the written test, otherwise the exam is passed (it is not possible to reject the mark). The oral exam (typically 2 or 3 questions) will focus on lectures and laboratory topics in a similar manner as the theoretical questions in the written test. The duration of the oral exam is strictly related to the preparation of the student. The mark will consider the completeness/correctness of the answers, as well as the ability of discussing critically the topics. The students must also upload the homework/report (described in the section Course Structure) within the day scheduled for the written exam. No additional point will be awarded for the homework. On the contrary, a penalty up to 2 points can be applied on the final mark in case of incomplete homework. The mark “30 cum laude” can be obtained in case of an outstanding exam (written only or written+oral) demonstrating a very deep knowledge of the subject. RULES SPECIFIC FOR ONLINE EXAM Both the written and the oral test will be performed in front of the webcam, according to the guidelines authorized by the Vice-Rector for Teaching. Video-surveillance will be carried out via the Virtual Classroom tool of the didactic web portal. A link to the Virtual Classroom will be sent about 15 minutes before the scheduled time. Students are recommended to connect as soon as possible. No extra time will be allowed for late connections. All sessions will be recorded and the video can be used for detecting any misconduct. At the end of each part of the written test the students must show the exam text on the webcam and send a clearly readable scan within 5 minutes. The correction of the written test with the comments will be sent by email to each student as soon as possible. Students with mark > 14/30 must communicate explicitly by email the desired option (accept/oral/reject) within 3 days after the date of publication of the results of the written test on the web portal. In case of no communication: • if the mark is higher than 20, such a mark becomes the final mark and the exam is passed. • if the mark is 20 or lower the exam is failed. Depending on the number of people and on their availability, a timetable will be prepared for the oral exams. The oral exam can be required at the discretion of the Exam Board, regardless of the mark of the written test, in case of: • suspicion of student misconduct during the written test (a non-correct use of the webcam could may raise suspicion), • lack of internet connectivity for more than 10 minutes overall (also non-consecutive), • scanned copy of the written test not uploaded on the web portal in time, In case of evidence of misconduct, the exam will be recorded as failed and the student will be deferred to “Commissione disciplinare” for punishment.

Modalità di esame: Prova scritta (in aula); Prova orale obbligatoria; Prova orale facoltativa; Prova scritta su carta con videosorveglianza dei docenti;

For the students attending the exam online, all rules reported in the section “Assessment and grading criteria for online exam” are valid. RULES SPECIFIC FOR ONSITE EXAM Both the written and the oral test will be performed in specific rooms designated for the exam. No extra time will be allowed for late arrivals. In case of withdrawal from the written test, the exam paper must be returned. The day scheduled for the oral exams will be also devoted for showing the corrected written tests and for clarifications about the corrections. The will to accept the mark, to take the oral exam or to reject the mark can be expressed in the same day. In case of absence and no communication by email: • if the mark is higher than 20, such a mark becomes the final mark and the exam is passed. • if the mark is 20 or lower the exam is failed. Appropriate actions will be taken against students who: • use any unauthorised source of information, • communicate or share written materials with other candidates, • attempt to read other candidates’ work. In case of misconduct, at discretion of the Exam Board: • the answer to some questions can be nullified (0 points will be assigned) • the student could be expelled from the exam room (the exam will be recorded as failed) and deferred to “Commissione disciplinare” for punishment.