Torque sensors in steering systems
Steering in cars consists of a large number of subsystems, which together form a very well-coordinated unit. In almost every new car exist power steering systems, which support the steering force applied by the driver and are thus important for comfort in the steering range. In order to determine the force applied to the steering wheel by the driver, there is a torque system which directly detects the momentums on the steering and serves as a control variable for the hydraulic or electric steering assistance.
The existing torque systems in steering systems are designed to meet the highest safety requirements in the steering area. The systems used today are partly in use for years and based on established technologies. The trend in steering systems goes clearly in the direction of “Steered by Wire” to prepare the car for use in autonomous vehicles. In “Steered by Wire” steering systems, the steering column is no longer directly connected to the steering axle that means that in these steering systems, the signals transmitted by the driver to the steering wheel are electronically detected and adjusted based on this information, the steering angle of the vehicle.
The trend of these systems shows the need for the integration capability of the sensor systems necessary to detect the driver signals. It is also necessary to detect a superimposition of the driver signals with a “Force Feedback”. Force feedback is needed as the driver needs haptic feedback when the handlebar is disconnected and therefore there is no torque on the steering column. The conventional torque sensors are not suitable for these applications. It is required to create new solutions. Trafag’s new technology for the development of magnetically inductive torque sensors opens up new application possibilities in this area. The torque sensors from Trafag can be dimensioned in a way so that you can measure the torque of the steering column without contact in the smallest possible space. The technological concept provides for redundant signal processing and, depending on the requirement, can be used in safetyrelevant applications. Also read more about the functionality of torque sensors! Other applications are also being developed in the field of agriculture, which is in preparation for the fully automatic harvesting machines. Wherever motors move machines, applications for contactless torque measurement arise.
Torque sensors in roll stabilizers for driving comfort
50 years ago, automobiles were a means of transport to get from A to B. The ride comfort was secondary and the focus was on the primary benefit. Due to ever-increasing demands on vehicle safety and driving comfort, completely different core aspects of the automobile have come to the fore in recent decades. The ticking clock of electromobility and autonomous driving will fundamentally change car culture as we know it today. In the cars of the future, more and more emphasis is placed on ride comfort and convenience. For example, the interior of the car is no longer a passenger compartment, but rather a living room in which the feel-good factor is the focus of the OEM and its developers.
The change in ride comfort also has a significant impact on the overall vehicle concept; in particular on the vehicle chassis and the associated driving dynamics. Functions such as torque vectoring, which on the one hand offer a safety function but also bring along a certain driving comfort factor, will come to the fore. Upgrading on the roads with e.g. SUVs do the rest to meet the need to create comfortable autonomous mobilities from static passenger compartments. This driver in the markets results in the need for sensors that are able to detect changes in the mechanics of the car and make the collected information available to intelligent control devices. This will help to achieve targeted actions for stabilization and comfort control. In 2016, the company Schaeffler received an innovation prize for the development of a roll stabilizer with integrated torque control. The integrated torque sensor is able to measure an introduced torque at a tilt of the vehicle from the central axis and to transmit the information to an electromechanical drive, which stabilizes the vehicle through targeted intervention and thus prevents roll. The first models of roll stabilizers were equipped without torque sensors and were perceived by customers in their function as rather disturbing, because without the sensitive detection of the torque, the regulation was very rough. This has led to the driver in the interior of the interventions as knocking felt.
This milestone in roll stabilizers is based on the integration of a passive magnetostrictive torque sensor, which requires parts of the roll stabilizer to be made of special material to memorize the necessary bias. The magnetostrictive torque sensor detects a change in magnetization due to a force. Magnetic Sense’s new magneto-inductive technology for measuring torques makes integration into a roll stabilizer possible without costly and expensive intervention in the existing system design of roll stabilizers. Through integration on the outer shell or in the interior of roll stabilizers, a very accurate detection of torques can be made possible and thus a comfortable regulation of the passenger compartment for the driver. The advancing developments in the automobile will certainly enable further necessities for the integration of torque sensors. Magnetic Sense magnetic-inductive torque sensors are ready to face these challenges.
