Differential (mechanical device): Difference between revisions

Revision as of 20:53, 7 October 2005

Revision as of 21:30, 21 October 2005

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==Active differential==

A relatively new technology is the electronically-controlled active differential. A computer uses inputs from multiple sensors, including [[yaw]] rate, steering angle, and lateral acceleration and adjusts the distribution of torque to compensate for undesirable handling behaviors like [[understeer]]. Active differentials are common in the [[World Rally Championship]], though they may be eliminated in the coming years.

The first use of this technology on a production automobile was [[Honda]]'s [[1997]] ''Active Torque Transfer System'' on the [[Honda Prelude|Prelude ''SH'']]. This "differential" was actually a [[planetary gear]]set placed next to an open front differential, not an integrated system. Fully integrated active differentials are used on the [[2005]] [[MR layout|MR]] [[Ferrari F430]] and on all four wheels in the [[Acura RL]].

The second constraint of the differential is passive – it is actuated by the friction kinematics chain through the ground. The difference in the torque on the tires (caused by theturns groundor atbumpy turning or bumpinessground) drives the second [[DOF]],(overcoming the torque of inner friction) to make levelequalise the driving torque on the tires. The sensibilitysensitivity of the differential depends on the inner friction through the second [[DOF]]. All of the differentials (so called “active” and “passive”) are usinguse clutches and brakes for restricting the second [[DOF]], so all are sufferingsuffer from the same disadvantage – decreasing of thedecreased sensibility of the differentialto ata dynamically changing environment. The sensibility of the computer controlled differential is also limited by the time delay caused by sensors and the response time of the actuators.

== History ==