AUTOMOTIVE RIDE AND TESTED
SENSORS THAT PERFORM RELIABLY IN HARSH, DEMANDING VEHICLE
ROAD TESTS AND DYNAMOMETERS Glenn Wedgbrow, business development manager at Micro- Epsilon UK, discusses some of the more challenging automotive test applications for non-contact displacement measurement, draw-wire and infrared temperature sensors.
A
s the development of next generation vehicles continues apace, the ride of a vehicle and the associated noise that it makes become increasingly important.
Without the normal engine noise to hide the sound, the squeal of brakes, squeaks of suspension and movement of pedals all suddenly become more apparent even though they have probably always been there. Manufacturers increasingly need to understand the movements and behaviour of key components and structures as part of the NVH testing and it is important that the instrumentation used to provide feedback does not itself affect the NVH results. Micro-Epsilon has been developing contact and non-contact displacement sensors for vehicle test applications for more than 50 years. These sensors are used in automotive R&D, test cells, production and for on-vehicle testing in almost every conceivable area of a vehicle. Applications include laser sensors for vehicle ride height, draw-wire (string pot) sensors for measuring suspension spring/damper movements and pedal travel; capacitive
sensors for measuring brake disc deformation; non-contact eddy current displacement sensors for measuring valve lift; and non-contact temperature sensors and thermal imaging cameras for measuring the temperature of on-vehicle components.
VEHICLE RIDE HEIGHT In automotive and motorsport applications, measuring vehicle ride height is critical. As speeds increase, the stability of the car and the aerodynamics employed must be carefully monitored to ensure the car stays on the ground. Non-contact laser displacement sensors have been developed to withstand the shock and vibration of being mounted to a vehicle. With the laser window pointing down towards the ground or racing track, the ILD1420 sensor series has been used extensively across all motorsport classes to accurately measure and monitor the ride height of their cars as they travel around the test track.
DEFORMATION OF BRAKE DISCS UNDER STRESS Non-contact capacitive displacement sensors are being used to obtain accurate data on the deformation of brake discs under stress. With high surface temperatures up to 600°C and typical deformations of less than 100μm, the high resolution capaNCDT non-contact capacitive displacement measurement system from Micro- Epsilon reliably measures the deformation of the brake disc under loading conditions. The measurement system also offers high bandwidth for frequency analysis up to the 10th harmonic, as well as high accuracy minimum zero shift with changes in temperature. In order to move the measurements from the dynamometer onto the real vehicle, the capaNCDT DTV system is available for measuring brake disc thickness variation. The included software features the ability to allow the engineer to take surface runout and thickness variation in- situ before and after each test run without dismounting the wheel, which would normally influence the results. In addition, a custom four channel sensor has been developed which has enabled customers to measure a full braking cycle of the vehicle with four tracks on each side of the brake disc simultaneously. Both single point infrared temperature sensors and thermal cameras from the thermoMETER and thermoIMAGER ranges are also being used to help vehicle development for brake temperature testing.
CRASH TESTS, SPRING AND PEDAL TRAVEL Draw-wire sensors from Micro-Epsilon are also being used in road tests, crash tests and simulators where they must meet the highest requirements in terms of wire accelerations, vibrations, shocks and limited installation space. For example, with a measuring range of 40mm and a possible cable acceleration of up to 60g, the wireSENSOR MT19 is particularly suitable for applications that require high dynamics such as vehicle crash test dummies, simulators and impact test rigs.
36 Autumn 2022 UKManufacturing
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