Electrical power steering


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This was my Seminar topic of M.Tech (auto).This will be helpful for somebody.

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  • Sir, it's really good to read, but i am having a doubt that @ what speed of the vehicle electric steering converts to manual steering, say ex;- 60 above. can you pls demonstrate on this doubt.
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  • sIR,
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  • Good work
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Electrical power steering

  1. 1. Advances in Steering Mechanisms. (First step to steer by wire) Presented by Arvind J. Bhosale SMBS 1
  2. 2. Outline1 Introduction2 System Overview3 Control Strategies4 Literature Review5 Applications and Benefits6 References7 Questions 2
  3. 3. IntroductionMainly focusing on electro-mechanical power steering 3
  4. 4. IntroductionRequirements Should be very accurate and easy to handle Effort required to steer should be minimum Should provide directional stability Easy alteration of driving direction 4
  5. 5. IntroductionFunctions To achieve angular motion of the front wheels to negotiate a turn To provide directional stability To provide perfect steering condition To facilitate straight ahead recovery after completing a turn To minimize tire wear 5
  6. 6. IntroductionClassification1.3.2 Based on the type of steering linkage or mechanism used Ackerman steering mechanism Davis steering mechanism1.3.2 Based on the type of Front axle used For independent wheel suspension For rigid axles suspension1.3.3 Based on the Steering Gearbox used Rack and pinion type Recirculating ball type Worm and wheel type Cam and double roller type Worm and nut type 6
  7. 7. Introduction1.3.4 Based on the type of power assist used Manual steering Power assisted steering • Hydraulic power steering • Electro-hydraulic power steering • Electric power steering 7
  8. 8. System OverviewOverview Of Electric Power Steering No requirement for hydraulic assistance (Eliminating hydraulic oil ) System provides assistance depending on the driving conditions Supports the “active return” function Easier for the driver to steer the vehicle in a straight line when the vehicle is being affected constantly by side winds or driven up or down hills 8
  9. 9. System OverviewTypes Of Electric Power Steering 1 Column type EPS 2 Pinion type EPS 3 Dual pinion type EPS 4 Offset Ball Screw type EPS 5 Direct drive type EPS 9
  10. 10. System Overview The electro-mechanical power steering with dual pinionSystem components Of EPS Steering wheel Steering column switch with steering angle sensor Steering column Steering moment sensor(Torque sensor) Steering gear Electro-mechanical power steering motor Power steering control unit 10
  11. 11. System Overview Actual View 11
  12. 12. System Overview Schematic View 12
  13. 13. System Overview Disassembled view 13
  14. 14. FunctioningThere are five general modes of operation of EPS 14
  15. 15. Functioning 15
  16. 16. Functioning 16
  17. 17. Functioning 17
  18. 18. Functioning 18
  19. 19. Control StrategiesControl architecture consists of two layers of control Effort level control (Torque Sensor) Assistance level control (Vehicle speed sensor) 19
  20. 20. Control StrategiesEffort Level Control Information like engine speed, and torque required are transmitted to control module, which determines the optimal degree of assistance the electric motor should apply (Contd.) 20
  21. 21. Control StrategiesEffort level control During any 120 degree interval of phase current I, the instantaneous power (P ) being converted from electrical to mechanical is P = ωT e = 2EI T e = Electromagnetic torque E = Induced EMF per phase. E = 2NphBgLrω, per phase induced emf Nph = Number of winding turns per phase Bg = Rotor magnetic field density L = Length of the rotor r = Internal radius of rotor (Contd.) 21
  22. 22. Control StrategiesEffort level control Using the above expression the electromagnetic torque is given by, T e = 4NphBgLrI = KφI Where, K = Torque constant φ = Flux per pole pair 22
  23. 23. Control StrategiesAssistance Level Control Figure shows the effort required to be produced by the motor for various vehicle speeds 23
  24. 24. Literature ReviewHistorical background of Power steering First power steering system was installed by a man with the surname of Fitts in 1876 Next power steering system was put on a Columbia 5-ton truck in 1903 First patent for power steering was issued to Robert E. Twyford (USA) on April 3, 1900 Francis W. Davis, in 1926 invented and demonstrated the first practical power steering system The first commercially available passenger car power steering system introduced in the 1951 on the Chrysler Imperial The first electric power steering system appeared on the Suzuki Cervo in 1988 24
  25. 25. Literature Review Control map 25
  26. 26. Literature Review Steering Effort 26
  27. 27. Literature Review Comparison of energy consumption 27
  28. 28. Applications 28
  29. 29. Benefits No hydraulic components, for example power steering oil pump, hoses, oil tank, filter No hydraulic fluid Space savings Reduction in noise Energy savings(fuel saving by 4%) No complex hose and wiring system Good straight-line stability Direct but soft application of the steering input No uncomfortable steering reactions over uneven driving surfaces 29
  30. 30. ReferencesResearch Papers1 Srihari Vijayakumar and Ram Chandran., Analysis of an Electric Power Assisted Steering System using Bond Graphs, SAE Paper No. 2003-01-05862 Shi Guobiao, Lin Yi., et al., Simulation of Straight-Line Type Assist Characteristic of Electric Power-Assisted Steering, SAE Paper No. 2004-01-11073 A. Emre Cetin, Banu Sinanoglu., et al., Compliant Control of Electric Power Assisted Steering Systems, SAE Paper No. 2005-01-35354 R Murugan, S Nandakumar ., et al., DSP-based electric power assisted steering using BLDC motor Bharat Electronics Limited, Nandambakkam, ChennaiBooks1 Lamm, Michael "75 years of Chryslers” Popular Mechanics 176 (3): 75, Year (March 1999)Magazines1 Popular Mechanics, Hearst Magazines2 Power Steering: The Pioneer Unit, Popular Science 30
  31. 31. 31
  32. 32. Questions 32