Use of the power steering to compensate for the negative effects introduced by a limited-slip differential

Abstract

The invention relates to a power steering device (1) for an axle assembly (2) provided with a limited-slip differential (7) designed to transmit a drive torque (C5) to a first wheel (4) and a second wheel (6) and to automatically activate, in the event of a loss of synchronism and/or of grip of one of the first and second wheels (4, 6), an operating mode referred to as "lockup mode" in which saiddifferential transfers most of the driving torque (C5) to the slower of the first and second wheels (4, 6), the power steering also comprising a steering mechanism (10) and a power steering motor (17)controlled by a control module (20), said steering control module (20) containing compensation laws which allow the power steering motor (17) to compensate for certain effects, such as alternating load backup or freezing, induced in the steering mechanism by activation of the differential lockup mode, so as to give the driver a feel close to that of an axle assembly (2) that does not have a lockup mode.

Description

technical field [0001] The present invention relates to power steering systems, and more particularly to power steering systems equipped with steering-plus-drive running gear in which the steering wheel operated by the steering system is also driven, that is, configured to transmit drive torque delivered by the vehicle's engine to the ground all or part of the vehicle in order to propel said vehicle. [0002] The invention relates more particularly to a steering system intended to operate a running gear equipped with a limited slip differential. Background technique [0003] It has long been known to equip driven undercarriages, usually comprising left and right drive wheels, with a differential which allows the left wheel to rotate at a speed different from that of the right wheel, especially when cornering Time. [0004] A recognized disadvantage of differentials is that in the event of a loss of adhesion (slip) on one of the drive wheels of the running gear, the drive t...

AI Technical Summary

Problems solved by technology

[0045] It should be noted that the phenomenon of force feedback is particularly sensitive near straight lines (i.e. when the vehicle follows a straight trajectory or approaches a straight line) and is therefore a strong source of discomfort to such an extent that, in this drive configuration, the strength of the steering assistance low, or even roughly zero, and thus may not be able to resist these force feedbacks, making the maintenance of the vehicle's heading particularly susceptible to said force feedbacks

[0046] Often, due to their side effects (which give the steering, and more generally the vehicle, a sometimes uncomfortable, sometimes disturbing behavior) can disturb the driver and cause him to react inappropriately, especially in the Limited slip differentials are generally considered incompatible for a range of applications on front wheel drive vehicles where the driver does not have experienced handling reflexes

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