Tài liệu đào tạo kĩ thuật viên HYUNDAI - hệ thống lái trợ lực điện( EPS- MDPS)
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POWER RACK AND
POWER RACK AND
PINION STEERING
PINION 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 Column
Power Steering Pump
Power Steering Gear
POWER RACK AND PINION
STEERING
System construction
System construction
POWER 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
-
Tubes
The 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 construction
POWER RACK AND PINION
STEERING
POWER RACK AND PINION
STEERING
Rack-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 end
2. Lock nut
3. Boot clip
4. Boot
5. Boot wire
6. Inner ball joint
7. Rack bushing
8. O-ring
9. Seal
10. Lock nut
11. Yoke plug
12. Spring
13. Support yoke
14. Snap ring
15. Seal
16. Bearing
17. Pinion shaft assembly
18. Bolt
19. Valve housing
20. O-ring
21. Steering gear housing
22. Mounting rubber
23. Mounting bracket
24. Oil pipe
25. Rack
26. Inner guide
Rack-and-pinion steering assembly
POWER RACK AND PINION
STEERING
In
Out
Left Turn
Right Turn
Right Turn
Oil Flow
Left Turn
Oil Flow
Cutaway of a Rack-and-Pinion steering gear
POWER RACK AND PINION
STEERING
Cutaway of a Rack-and-Pinion steering gear
POWER RACK AND PINION
STEERING
POWER RACK AND PINION
STEERING
Torsion bar
Bearing
Input shaft
Yoke spring
Rack
Pinion gear
From oil pump
To oil reservoir
B
Rotary valve
Bearing
[Section A-A]
Cutaway of a Rack-and-Pinion
steering gear
Cutaway of a Rack-and-Pinion steering gear
POWER RACK AND PINION
STEERING
To cylinder tube right chamber
To cylinder tube left chamber
Torsion bar
Rotary valve
Input shaft
To oil reservoir
From oil pump
[Section B-B]
Operation of the pinion and valve assembly (at the center position)
POWER RACK AND PINION
STEERING
Chamber “A”
Port a
Port d
To the left
cylinder tube
From the oil pump
To the right cylinder tube
Port c
Port b
Operation of the pinion and valve assembly (at the center position)
POWER RACK AND PINION
STEERING
Oil pump
Oil reservoir
R’
Oil passage-way R
Oil passage-way L
L’
Operation of the pinion and valve assembly (at the center position)
POWER RACK AND PINION
STEERING
Housing
Oil reservoir
Oil pump
Port a Port d
Cylinder tube
left chamber
Cylinder tube right chamber
Chamber “A”
Torsion bar
Input shaft
Sleeve a
Operation of the pinion and valve assembly (turning left)
POWER RACK AND PINION
STEERING
Chamber “A”
Port c
Port d
To the left
cylinder tube
From the oil pump
From the right cylinder tube
Port b
Port a
Operation of the pinion and valve assembly (turning left)
POWER RACK AND PINION
STEERING
Oil pump
Oil reservoir
R’
Oil passage-way R
Oil passage-way L
L’
Operation of the pinion and valve assembly (turning left)
POWER RACK AND PINION
STEERING
Oil reservoir
Oil pump
Sleeve c
Chamber “A”
Port b
Sleeve b
Sleeve a
Sleeve b
Port d
Port a
Port c
Operation of the pinion and valve assembly (turning right)
POWER RACK AND PINION
STEERING
Chamber “A”
Port d
From the left cylinder tube
From the oil pump
To the right cylinder tube
Port b
Port a
Input shaft
Torsion bar
Rotary valve
Port c
Operation of the pinion and valve assembly (turning right)
POWER RACK AND PINION
STEERING
Oil pump
Oil reservoir
R’
Oil passage-way R
Oil passage-way L
L’
Cylinder tube
left chamber
Cylinder tube
right chamber
Operation of the pinion and valve assembly (turning right)
POWER RACK AND PINION
STEERING
Oil reservoir
Oil pump
Port c
Port d
Cylinder tube
left chamber
Cylinder tube right chamber
Chamber “A”
Torsion bar
Input shaft
Sleeve b
Port b
Sleeve b
Rotary valve
Sleeve a
Sleeve c
Port a
POWER STEERING PUMP
Oil pump construction
1. Pulley
2. Shaft
3. Pressure switch
4. P/S pump body
5. Flow control valve ass’y
(built in relief valve)
6. Cam ring
7. Rotor
8. Vane
9. Cover
Oil pump construction
POWER STEERING PUMP
Operation of the oil pump
POWER STEERING PUMP
Intake side
Vane
Rotor
Cam ring
Discharge
Discharge
Discharge
Discharge
Suction
Suction
Suction
Suction
Rotating
direction
