APPLICATION NOTE – Made for harsh environments: Variohm EuroSensor leads the way for motorsport sensors

Subjected to large temperature extremes, elevated shock and vibration levels as well as exposure to dirt, oil and corrosive fluids, sensors used in the motorsports industry for monitoring position, pressure and temperature see some of the harshest conditions imaginable for instrumentation measurement tasks. As technology advances and motorsport data acquisition becomes progressively more sophisticated, the industry continues to challenge manufacturers like Variohm EuroSensor for sensor advances that will help deliver the dynamic improvements that race teams require to optimise car and driver performance. Such improvements include but are not restricted to increased sensor precision, resilience to drift over time and temperature with near-perfect measurement linearity and repeatability – and of course the upmost reliability and long-lifetime endurance for the incredibly harsh track test and race conditions.

Variohm’s comprehensive range of motorsport sensors include linear and rotary position sensors, piezo resistive pressure transducers, infra-red and resistive technology temperature sensors, as well as wheel-speed sensors, accelerometers and gyro sensors.

Linear position sensors are principally used for ride height which is constantly monitored to confirm the suspension characteristics of the car through acceleration, braking and cornering. When measured against time and track sections through GPS – and usually with several position sensors on key zones of the car, the ride height becomes a critical factor to set the car up and develop race strategy. A typical ride height application would use Variohm’s ELPM series linear position sensors covering measurement ranges from 25 mm to 175 mm with independent linearity to +/- 0.5%. The ELPM is available in a motorsport version with an optional internal dual-lip seal arrangement that offers enhanced reliability and improved endurance. The 9.5 mm diameter sensor is lightweight and compact with IP67 protection and a 150⁰ C upper temperature rating (175⁰ C short term). The ELPM features a patented multi-fingered precious metal wiper system that is elastomer-damped, enabling full contact with the linear sensor’s conductive plastic resistance element for consistent unbroken voltage proportional measurement. This proven design ensures error-free results and extremely low electrical noise even under the toughest physical and environmental conditions. The EPLM’s is mounted via self-aligning pivot bearings and an optional ‚POP‘ version enables fast installation or removal.

Motorsports angular position measurement is often associated with steering angle or throttle valve position as well as gearbox position and suspension. Variohm has a long history of success for this application area and has developed and honed its product offerings to maximise durability and performance. Its latest product designs feature Hall effect technology which is non-contacting and so offers an extremely long-life measurement solution. There are five main product lines that fall into this category that offer a broad choice of installation flexibility to suit the customers mounting requirements. All offer 5 VDC input with CW or CCW direction in single or dual redundant angle measurement versions with ratiometric or PWM signal level output and programmable angles from 30⁰ to 360⁰ in 1⁰ increments. The Euro CMRS and Euro CMRT both feature a shaft design with bearings. The smaller CMRT series is just 10 mm in diameter with an M8 threaded mounting whilst the CMRS has a slightly larger anodised aluminium housing diameter of 10.5 mm and an 18 mm PCD slotted flange mounting. The Euro CMRK is a miniature puck and magnet rotary sensor. Its two-part design maintains a completely non-contacting angle measurement solution with no bearings and minimal axial length and 16.5 mm diameter PCD slot mounting for very compact installation. These compact sensors with encapsulated sensor electronics offer a vibration rating that meets IEC 600068-2-6 and temperature range from -40° C to +125° C, with short term operation to 150° C. Variohm also recommends the Euro-XPD model for motorsport applications. Its 8 mm diameter D-shaft drive option which is available with a choice of 32 or 38 mm PCD mounting, meets the requirements of the motorsports industry and is particularly aimed at throttle position sensing, without the need for a separate coupling. Also available is the Euro-XPK – another puck and magnet design with a larger 38 mm PCD slot mounting that is favoured by some race teams and performance car manufacturers.

Pressure sensors for motorsports include oil, fuel and coolant pressure measurement as well as manifold absolute pressure. Variohm’s comprehensive range of piezo resistive pressure transducers, which are used across many other industries, include absolute, gauge and differential pressure measurement in several pressure range variants from a few millibars up to 5000 bar. Voltage and current output options are fully covered as well as signal output variants such as CANopen, and J1939 (SAE-J1939). Variohm’s EPT series, developed over several years, comprehensively covers all pressure port configurations specified in motorsports with stainless steel and other materials options for housings and wetted parts in standard and miniature versions. Environmental ratings to IP69K ensure high resistance to debris and water ingress and solid-state sensor electronics safeguard the sensors‘ resistance to vibration which for brake pressure monitoring can be specified to 16 g peak (20 to 2000 Hz) with shock levels to 1000 g. The EPT series also returns a high resilience to temperature extremes with typical ratings from -40° C to +125° C. Variohm’s recently launched SMO3100 pressure transducers have all the characterises of the EPT series with addition E1 automotive approval. Detailed specifications for all Variohm pressure sensors include non-linearity, repeatability and stability as well as temperature coefficient and compensated range values.

Temperature sensing in motorsports includes coolant, brake, tyre and exhaust gas monitoring. Users can choose from a very comprehensive range that includes resistive technologies as compact industrial quality sensors with process connection type mountings or temperature probes as embedded components such as hexagonal bolts or specialised probes. Specialised motorsport high temperature probe sensors are also available exhaust. Also available are non-contacting infra-red sensors typically used for tyre temperature monitoring.

Variohm’s EPT2100 series temperatures sensor is widely used by the motorsports industry. It has the same environmental resilience – temperature shock and vibration – as the previously covered pressure sensors with a similar mounting and dimensional characteristics. Based on the exceptionally reliable and well proven PT100 measurement element, the sensor has a temperature measurement range from -40° C to +150° C with +/- 0.5% accuracy in voltage or ratiometric output. Variohm also manufacture combined temperature/pressure sensors, enabling a single spacesaving device to take measurements of both variables.

Variohm’s range of premium quality EGT series type K thermocouple exhaust gas temperature probes, supplied by its distribution partner ZIP, are widely used in motorsports. A wide temperature range from -100° C to +1300° C and compatibility with the corrosive fuel exhaust gases used in the industry safeguard high reliability whilst a choice of probe diameters and mounting hardware assure installation flexibility. Variohm’s Infra-Red technology tyre temperature sensors include single- and multi-channel versions with temperature ranges from -20° C to +200° C. With +/- 1% typical full-scale accuracy and a measuring distance offset up to 400 mm, these sensors are built for the harsh conditions encountered in motorsports.

Variohm also includes Hall Effect speed sensors in its motorsports product range. Variohm’s own Euro-WS series and the VR09 by Texense offer 20 kHz sample rate with mounting flexibility for convenient installation. Also, from Texense and fully supported by Variohm motorsports technical sales team, a range of gyroscopes, accelerometers and a 6-axis inertial sensor with integrated signal conditioning find applications with professional race teams where comprehensive dynamic vehicle behaviour can be interpreted and analysed.

Variohm EuroSensor is a UK and European based sensor designer and manufacturer, and a distribution partner for leading sensor component suppliers for linear and rotary position, load, force, vibration and temperature measurement. With its own production and assembly capability, the sensor specialist provider supplies motorsport rated sensor solutions to F1, A1GP, WTCC, GP2, Champ, Nascar, ALMS, Superbike, and many other series. For further information visit www.variohm.com