Infiniti Q45. Manual - part 883

ELECTRICALLY CONTROLLED POWER STEERING

STC-35

[WITH REAR ACTIVE STEER]

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System Diagram

NGS000CO

COMPONENTS FUNCTION DESCRIPTION

CAN Communication

NGS000CP

SYSTEM DESCRIPTION 

CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle mul-
tiplex communication line with high data communication speed and excellent error detection ability. Many elec-
tronic control units are equipped onto a vehicle, and each control unit shares information and links with other
control units during operation (not independent). In CAN communication, control units are connected with 2
communication lines (CAN-H line, CAN-L line) allowing a high rate of information transmission with less wiring.
Each control unit transmits/receives data but selectively reads required data only.
For details, refer to 

LAN-35, "CAN COMMUNICATION"

 .

SGIA1446E

Component parts

Function

RAS control unit

Controls power steering solenoid valve (with fail-safe function).

Power steering solenoid valve

Controls oil pressure in gear housing assembly.

VDC/TCS/ABS control unit

Transmits vehicle speed signal via CAN communication to RAS control unit. (For fail-safe conditions)

ECM

Transmits engine speed signal via CAN communication to RAS control unit.

STC-36

[WITH REAR ACTIVE STEER]

REAR ACTIVE STEER SYSTEM

REAR ACTIVE STEER SYSTEM

PFP:28505

Power Steering Control Diagram

NGS0006Z

Operation Principle

NGS000CY

OPERATION PRINCIPLE

The rear wheel angle changes as per the following:

During high-speed driving

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The rear wheels turn to the same phase of front wheels regard-
less of the operation speed of steering wheel.

During middle- low-speed driving

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When turning the steering wheel rapidly, the rear wheels turn to
the opposite phase of front wheels for a moment just after start-
ing the steering wheel operation. And then, they turn to the
same phase.

1.

Rod

2.

Offset shaft

3.

Gear housing assembly

4.

RAS motor

5.

Motor shaft

6.

Rear wheel steering angle sensor

7.

HRH gear

SGIA1577E

SGIA1440E

SGIA1441E

REAR ACTIVE STEER SYSTEM

STC-37

[WITH REAR ACTIVE STEER]

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STC

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The rear wheels turn to the same phase of front wheels when
turning the steering wheel slowly.

During extremely slow-speed driving and at straight-ahead

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The rear wheels do not turn during extremely slow-speed driving regardless of the operation speed of
steering wheel.

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The rear wheels do not turn at straight-ahead regardless of the vehicle speed.

System Description

NGS00070

DESCRIPTION

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RAS control unit controls the rear active steer.

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RAS actuator assembly senses the front wheel steering angle and the vehicle speed by RAS control unit.
RAS control unit controls the RAS actuator assembly according to the steering operation amount.

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Model following control is used to rear active steer.

Model Following Control

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Situation :
The rear wheels turn to the opposite phase of front wheels for a
moment so as to improve the start-up of yaw rate (steering angle
speed).

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Situation :
The rear wheels turn to the same phase of front wheels after
securing the necessary yaw rate (steering angle speed) to cor-
nering.

RAS ACTUATOR ASSEMBLY

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It is driven by RAS motor.

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Maintain the toe-stiffness of rear wheels against the road external force because the irreversible efficiency
performance hypoid gear is used.

Irreversible Efficiency Performance

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The power from the pinion gear (motor side) is transmitted, but the pinion gear does not rotate as caused
by the gear mechanical characteristics (teeth angle) even though the ring gear (tire side) starts to rotate.

STEERING ANGLE SENSOR

It detects the neutral position and steering angle of steering wheel.

REAR WHEEL STEERING ANGLE SENSOR

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It detects the steering angle condition of rear wheel.

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2 systems (main sensor and sub-sensor) are adopted.

SGIA1442E

SGIA1439E

STC-38

[WITH REAR ACTIVE STEER]

REAR ACTIVE STEER SYSTEM

CONTROL UNIT

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Controls the RAS actuator assembly so that it will be proper that
the steering angle of rear wheel is calculated by RAS control
unit (1) from input signal from each sensor.

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Self-diagnosis can be done.

RAS WARNING LAMP

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Turns ON when there is a malfunction in rear active steer system.

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Turns ON when ignition switch is turned ON, for purpose of lamp check. Turns OFF approximately for 1
second after the engine starts if system is normal.

System Diagram

NGS00071

SGIA1444E

SGIA1447E