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# JACKKNIFE PREVENTION USING VARIABLE FORCE SPRINGS

IP.com Disclosure Number: IPCOM000240566D
Publication Date: 2015-Feb-09
Document File: 2 page(s) / 121K

## Publishing Venue

The IP.com Prior Art Database

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 51% of the total text.

Page 01 of 2

JACKKNIFE PREVENTION USING VARIABLE FORCE SPRINGS

The current approach to prevent a jackknife condition in a vehicle-trailer system is to measure the hitch angle and the trailer length. These values are used to determine if we have reached a critical angle, where if we continue going on reverse, it results in a jackknife condition. This condition is determined by what has been named the jackknife equation:

Where, max is the maximum steering angle achievable by the vehicle, max is the largest hitch angle after which a jackknife condition will occur, W is the front to rear axle distance of the vehicle, D is the trailer length and L is the distance between the rear axle of the vehicle and the hitch point.

The above approach has the drawback that it requires knowledge of D, L and W as well as max and max.

Other methods use yaw rate sensors in the vehicle and the trailer to determine hitch angle and the trailer length. Again, these methods require sensors to be added to the trailer and the vehicle to make a determination if the customer is about to jackknife the trailer.

Our proposal is to provide a means to avoid jackknife and to also be able to display to the customer when we are near the "critical jackknife angle" , max.

Please find below two simple sketches depicting the idea of our disclosure:

The first sketch (on the left side) it shows a rear bumper with a draw bar in the middle of the bumper attached to a hitch which also has a trailer attached to it. S1 and S2, represent two springs which could be simple coils or motor controlled (or any other type) that would allow us to control the effective stiffness.

One of the unique ideas of this concept involves the fact that the force required to prevent rotation from the trailer (at a fixed distance from the hitch, by S1 or S2) is related to the moment arm of the trailer length, D. The longer D is, the higher the required force (of spring S1 or S2) to prevent the rotation. This in effect results in a more restrictive movemen...