Ferrari applies for a new patent to improve rear wheel steering level

2024-01-22

According to foreign media reports, Ferrari has applied for a new patent from the European Patent Office, which is based on the Virtual Short Wheelbase system for individual rear wheel control, which can improve various aspects of car fuel consumption, tire wear, and even driving dynamics. It is reported that the virtual short wheelbase system has already been installed in the Ferrari Purosangue.

The special feature of this patent is that Ferrari does not need to develop new hardware for it, only adding a layer of software control on top of the existing hardware is necessary.

The current Rear Wheel Steering (RWS) system is quite complex, and its computer can seamlessly transition between different operational requirements. When driving at low speeds, such as when driving or parking in a city, the steering of the rear wheels and front wheels of the car is opposite, which can reduce the turning radius of the vehicle and make it easier to move in narrow spaces.

At higher speeds, the function of RWS is opposite to that at low speeds, with the rear wheels turning the same as the front wheels, thereby suppressing high-speed turns or avoiding any high-speed rotations during operations, keeping the car stable and pointing in the correct direction. RWS has also improved the off-road capabilities of the Ferrari Purosangue.

One limitation of most current applications is that the rear wheels run in series, meaning that one wheel replicates the direction of another turn and the rear wheels remain largely parallel within their range of steering motion. Although most RWS systems have separate actuators for each wheel, they are programmed to maintain the same movement of the rear wheels. Whether due to design constraints or computational limitations, this serial connection is clearly not the best way to use hardware.

Ferrari's new patent indicates that under most driving conditions, the new RWS system operates in the same direction/reverse as existing products when turning the steering wheel, but during acceleration, the new system operates in a straight line and achieves maximum mechanical grip in bends.

In straight-line cruising, Ferrari's new system applies some steering force to the rear wheels, causing them to point directly forward, covering any toe setting that may belong to the standard wheel alignment settings of the car. This operation can reduce tire wear, resulting in lower rolling resistance and slightly improved fuel efficiency.

Under strong acceleration, the impact of torque may cause the powerful Ferrari V12 parking space to lose control. But the new RWS can achieve effective control, and its stability and traction control can be well managed. In addition, the Ferrari RWS system also adds a few degrees of toe angle (slightly inward pointing) to drive the rear wheels, significantly reducing fishtail inclination and reducing the need for stability management systems to cut off power, apply brakes, or transfer torque from one drive wheel to another. Combined with Ferrari's electronic differential control, the new RWS will increase linear acceleration without causing the car to collide with obstacles from behind.

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