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ToyotaVGRS 1

The document discusses the Variable Gear Ratio Steering (VGRS) system used in certain Toyota vehicles. The VGRS system uses an actuator and ECU to variably adjust the steering gear ratio based on driving conditions, providing optimal steering feel and control both at low and high speeds. It ensures easy maneuverability at low speeds while improving stability at higher speeds. The system electronically transmits steering force through the actuator rather than using a direct mechanical connection.

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Dilan S Gamachchige
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164 views1 page

ToyotaVGRS 1

The document discusses the Variable Gear Ratio Steering (VGRS) system used in certain Toyota vehicles. The VGRS system uses an actuator and ECU to variably adjust the steering gear ratio based on driving conditions, providing optimal steering feel and control both at low and high speeds. It ensures easy maneuverability at low speeds while improving stability at higher speeds. The system electronically transmits steering force through the actuator rather than using a direct mechanical connection.

Uploaded by

Dilan S Gamachchige
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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I..

exus LX470 vehicles produced


from August 2002 onwards and
Land Cruiser 100 Series Sahara
VGRS System Function
In the conventional steering system, the
gear ratio is set primarily for the high-
How It Works
When the driver turns the steering
wheel, turning force is transmitted
models produced from May 2005 are
speed driving mode to prevent the vehicle to the steering rack.via the VGRS
fitted with a Variable Gear Ratio Steering
from making over-sensitive movements actuator (located between the steering
(VGRS) system which has unique service
in response to the driver's steering input. main shaft and the steering rack).
procedures relating to wheel alignment.
For this reason, it requires a large driver's
battery terminal re-connection and other In basic terms, during normal
steering input while driving at low speeds.
service repairs. This article is provided by operation the steering wheel is not
Toyota and explains basic system function, In the VGRS system, the steering gear ratio 'mechanically connected' to the front
operation and also provides details on alters to suit the driving conditions. The wheels. Steering force applied at
very important service procedures. VGRS ECU operates the VGRS actuator in the steering wheel is transmitted to
order to constantly achieve the most optimal the steering rack through an electric
gear ratio in accordance with the driving motor within the VGRS actuator.
conditions of the vehicle. This ensures a high
level of manoeuvrability and stability between The VGRS ECU determines the VGRS
the low- and high-speed driving ranges. actuator ratio (based on signals
received from sensors) via operation
In the extremely low-speed range, which of the actuator motor and reduction
occurs when the driver is attempting to gear mechanism. See Diagram 3.
park the vehicle, this system changes the
steering gear into the smallest gear ratio The reduction gear mechanism within
in order to reduce the driver's steering the VGRS actuator is a 'strain wave'
input. Additionally, at low- to mid-speed. type reduction gear. See Diagram 4. The
range, the driver's steering input is also reduction gear operates at a 50:1 ratio.
somewhat reduced, thereby improving the When the ignition switch is turned
'agility' of the vehicle. See Diagram l. off, or when a system abnormality
In the high-speed range, the steering occurs, a lock mechanism stops the
gear ratio is set to the maximum level to motor. Whilst this 10«< mechan~is
~ VSRS Actuator prevent the vehicle from making over- engaged, the steerin~1'urning
sensitive movements in response to the force is directly transmitted to the
driver's steering input (ensuring a more steering gear box (as per a conventional
stable vehicle response). See Diagram 2. steering system). See Diagram 5.

52 AUSTRALIAN AUTOMOTIVE

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