Tài liệu đào tạo kĩ thuật viên HYUNDAI - hệ thống lái trợ lực điện( EPS- MDPS)

Tài liệu đào tạo kĩ thuật viên HYUNDAI - hệ thống lái trợ lực điện( EPS- MDPS) A typical power rack-and-pinion steering assembly is used on many cars. This rack-and-pinion assembly is a hydraulic-mechanical unit with an integral pis

POWER RACK AND POWER RACK AND PINION STEERINGPINION STEERING A typical power rack-and-pinion steering assembly is used on many cars. This rack-and-pinion assembly is a hydraulic-mechanical unit with an integral piston and rack assembly. An internal rotary valve direct power steering fluid flow and controls pressure to reduce steering effort.When the steering wheel is turned, resistance created by the weight of the car and tires-to-road friction causes a torsion bar in the rotary valve to deflect. This changes the position of the valve spool and sleeve, thereby directing fluid under pressure to the proper end of the power cylinder.The difference in pressure on either side of the piston (attached to rack) helps move the rack to reduce turning effort. The fluid in the opposite end of the power cylinder is forced to the control valve and back to the pump reservoir. When the steering efforts stops, the control valve is centered by the twisting force of the torsion bar, pressure is equalized on both sides of the piston, and the front wheels return to the straight ahead position.POWER RACK AND PINION STEERING Steering ColumnPower Steering PumpPower Steering GearPOWER RACK AND PINION STEERINGSystem construction System constructionPOWER RACK AND PINION STEERING The rack-and-pinion power steering system consists of:- Rack and pinion steering gear box- Power steering oil pump- Oil reservoir- TubesThe power steering system uses a hydraulic pressure which is generated by the power steering pump to reduce the effort required to turn the steering wheel. The power steering pump is mounted on the front of the engine. The pump has a vane-type design, and is driven by the crankshaft through a drive belt.The power steering fluid is drawn into the pump from the reservoir when the engine is running. The fluid is pressurized by a power steering switch and a control valve located in the power steering pump.System constructionPOWER RACK AND PINION STEERING POWER RACK AND PINION STEERINGRack-and-pinion steering linkage Rack-and-pinion linkage connects the gear to the steering knuckles. The construction of the Rack-and-pinion linkage is tie rod ends, Lock nut, Boot, Inner ball joint, Rack, Pinion shaft assembly, Steering gear housing, Oil pipe, Bearings, Seals, Bushings, O-rings. One end of the inner tie rod is inside the steering gear and is connected with the inner ball joint. The inner tie rod is protected from the elements by a rubber boots. The outer part of the inner tie rod is a threaded shaft and the outer tie rod is threaded onto this shaft and held in place by a locknut. Toe adjustment is made by loosening the locknut and turning the inner rod to shorten or lengthen the tie rod assembly. POWER RACK AND PINION STEERING POWER RACK AND PINION STEERING 1. Tie rod end2. Lock nut3. Boot clip4. Boot5. Boot wire6. Inner ball joint7. Rack bushing8. O-ring9. Seal10. Lock nut11. Yoke plug12. Spring13. Support yoke14. Snap ring15. Seal16. Bearing17. Pinion shaft assembly18. Bolt19. Valve housing20. O-ring21. Steering gear housing22. Mounting rubber23. Mounting bracket24. Oil pipe25. Rack26. Inner guideRack-and-pinion steering assemblyPOWER RACK AND PINION STEERING InOutLeft TurnRight TurnRight Turn Oil FlowLeft TurnOil FlowCutaway of a Rack-and-Pinion steering gearPOWER RACK AND PINION STEERING [...]... of a Rack-and-Pinion steering gear POWER RACK AND PINION STEERING Cutaway of a Rack-and-Pinion steering gear Torsion bar Bearing Rotary valve From oil pump Input shaft To oil reservoir B Yoke spring Pinion gear Bearing [Section A-A] Rack POWER RACK AND PINION STEERING Cutaway of a Rack-and-Pinion steering gear To cylinder tube right chamber To cylinder tube left chamber Torsion bar [Section B-B] To oil... left cylinder tube From the oil pump To the right cylinder tube POWER RACK AND PINION STEERING Operation of the pinion and valve assembly (at the center position) Oil pump Oil passage-way L L’ Oil reservoir R’ Oil passage-way R POWER RACK AND PINION STEERING pinion and valve assembly (at the center position) Operation of the Torsion bar Chamber “A” Input shaft Housing Oil reservoir Sleeve a Oil pump... To the left cylinder tube From the oil pump From the right cylinder tube POWER RACK AND PINION STEERING pinion and valve assembly (turning left) Operation of the Oil pump Oil passage-way L L’ Oil reservoir R’ Oil passage-way R POWER RACK AND PINION STEERING pinion and valve assembly (turning left) Operation of the Port b Chamber “A” Sleeve b Oil reservoir Oil pump Sleeve a Sleeve c Sleeve b Port d Port... Rotary valve From the left cylinder tube POWER RACK AND PINION STEERING pinion and valve assembly (turning right) Operation of the Oil reservoir Oil pump Oil passage-way L L’ Cylinder tube left chamber R’ Cylinder tube right chamber Oil passage-way R POWER RACK AND PINION STEERING pinion and valve assembly (turning right) Operation of the Chamber “A” Torsion bar Input shaft Port b Sleeve b Rotary valve... The steel ball in the relief valve is under the hydraulic pressure in the circuit coming through orifice A2 When the steering wheel is turned and the hydraulic pressure increases higher than 7 5-8 2kg/cm2 (106 0-1 160 psi), it compresses the relief spring to push the steel ball which then allows the fluid to flow to the power steering pump POWER STEERING PUMP Relief Valve Such relief valve operation causes... higher, opening in the orifice is made narrower and fluid flow to the gear box reduces As a result, hydraulic pressure application is slow at the start of the steering wheel turn This provides straight-ahead stability to suit the driving condition with the steering wheel operated near its neutral position POWER STEERING PUMP Relief Valve • Orifice A2 • Relief valve spring • Steel ball • Chamber A •... Oil reservoir Suction hose Oil pump EPS Gear box Return hose EPS FEATURES The EPS not only performs the ordinary power steering functions but also controls the hydraulic pressure acting on the counter-force plunger provided in the input shaft section of the gear box, thereby varying the steering effort vs hydraulic pressure characteristics according to the vehicle speed to provide optimum steering... force from the road surface, it does not affect directional control, as the output hydraulic pressure for the steering effort becomes high as in the conventional power steering (6) The system has a fail-safe function so that even if the electrical system, including the control unit and sensors fails, the steering characteristics of a vehicle with normal power steering will be retained  . STEERING The rack-and-pinion power steering system consists of :- Rack and pinion steering gear box- Power steering oil pump- Oil reservoir- TubesThe power. STEERINGRack-and-pinion steering linkage Rack-and-pinion linkage connects the gear to the steering knuckles. The construction of the Rack-and-pinion linkage