Model 3

Tesla points to better range and efficiency with compact power steering patent

The Tesla Model 3's minimalistic interior. (Credit: Tesla)

Tesla’s electric cars are already among the most efficient vehicles on the market, and this is shown by the immense gap between the range and efficiency of the company’s vehicles compared to their competitors from veteran automakers. Part of the reason behind this is Tesla’s continued improvements in its vehicles, which are rolled out and adopted as soon as they are refined and ready. 

One of these improvements appears to have been teased in a recently-published patent application. Simply titled “Steering System for a Vehicle,” the document describes a smart, novel way of designing a power steering system that is more compact and less power-hungry. In the patent’s background, Tesla remarked that conventional power steering systems, which are usually hydraulically operated, are mostly bulky and space-consuming.

This is due to power steering systems utilizing a number of components that include cylinders, pumps, hoses, and control valves, to name a few. Hydraulic power steering systems also have complex designs, which add cost to a vehicle. Lastly, conventional power steering systems generally require a large amount of power to function. With this in mind, Tesla argues that there is a need for a new power steering system that is simpler, smaller, and more power-efficient. 

Illustrations showing different perspective views of Tesla’s steering system patent. (Credit: US Patent Office)

Tesla’s novel power steering design involves fewer parts than the conventional system used in most vehicles. The electric car maker describes the design in its patent in the description below. 

“The steering system includes a drive motor having a motor shaft. The steering system also includes a first gear reduction stage for receiving a first rotational input from the motor shaft and providing a first rotational output. A first gear meshes with a second gear of the first gear reduction stage via a helical gear mesh. The steering system further includes a second gear reduction stage for receiving the first rotational output from the first gear reduction stage and providing a second rotational output. 

“The second gear reduction stage may include at least one of a strain wave gearing, a worm drive, and a planetary gearing. In case the second reduction stage is a strain wave gearing, the second gear reduction stage includes an ovular coupler, a flexible coupling, an outer spline, and a plurality of bearing members disposed between the ovular coupler and the flexible coupling. The steering system includes an output shaft for receiving the second rotational output from the second gear reduction stage.”

Tesla notes that its smaller, power-saving steering system, apart from being more power-efficient and compact, also includes several failsafes, which could, in turn, increase a vehicle’s safety. The company’s patent mentions “sacrificial or failsafe components,” which are designed to safeguard a vehicle’s sensitive components during the event of a breakdown. Such a design will likely contribute to Tesla’s electric cars and their already-stellar safety ratings. 

An illustration of a steering system for a vehicle, according to certain embodiments of Tesla’s patent. (Credit: US Patent Office)

“In some embodiments, steering system 102 has been shown to provide a 10% improvement over a hydrolytic steering system. Additionally, steering system 102 is a compact unit that consumes lesser space as compared to other steering systems that are commercially available in markets. Further, steering system 102 does not require large amount of additional power for operation. FIG. 6 illustrates a failure mode of steering system 102 in which one or more bearing members 244 of steering system 102 fail. Bearing members 244 of steering system 102 are designed to withstand high loads so that they do not fail during normal vehicle operation. However, bearing members 244 may be designed to withstand only a predetermined threshold of load. As a result, bearing members 244 fail when they are loaded beyond the predetermined threshold. 

“For example, a bearing member 258 may eventually fail along a shear plane 260 when loaded beyond the predetermined threshold. Alternatively, bearing members 244 may undergo a bending failure, or any other type of failure. In such a situation, one bearing member 244 is a sacrificial or failsafe components, thereby safeguarding other components of vehicle, for example, drive motor 204 or an engine, against breakdown or seizing. More particularly, the one bearing members 244 fails, ovular coupler 238 locks and rotates with flexible coupling 240. Thus, steering system 102 can still be operated to allow vehicle to be driven for a certain distance and parked at an appropriate location. Bearing member 244 fails according to a sheer mechanism or another failure mechanism. Further, failed bearing member 258 can be replaced and vehicle can be reinstated without incurring any additional losses.”

It remains to be seen if Tesla’s compact power steering system will be adopted for the company’s upcoming vehicles. That being said, such a system is a perfect match for EVs such as the Tesla Semi, the Tesla Pickup Truck, and the Model S and X Plaid Powertrain variants. These are all large vehicles, and their success in the market will likely be determined in no small part by their range and efficiency. In this light, every single innovation that could optimize these vehicles’ efficiency will most definitely be appreciated. After all, the less power is consumed by subsystems such as a vehicle’s power steering unit, the more power there is to turn an electric car’s wheels. 

The full text of Tesla’s compact, efficient power steering system could be accessed here.

Tesla points to better range and efficiency with compact power steering patent
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