Custom inductive displacement and position sensors

Micro-Epsilon has engineered custom inductive displacement and position sensors for OEMs in a variety of industry sectors such as hydraulics and pneumatics, aerospace and defence, automotive, agricultural machinery, off-highway vehicles, household appliances and medical devices.

Due to its high production capacity (up to one million sensors per year), Micro-Epsilon can deliver cost-effective sensors for applications where the highest standards apply. These include sensors for use in high atmospheric pressures, high temperatures and high vibrations, as well as for vacuums, hazardous (ATEX-certified) environments and clean rooms. A wide range of catalogue and modified sensors form the basis for relatively quick and simple adaptation to many custom OEM applications.

Customisation options

Chris Jones, Managing Director at Micro-Epsilon UK, comments: "Often we come across applications where standard traditional inductive sensors and controllers are not suitable, as the technical requirements of the application cannot be met by standard catalogue inductive sensors in the marketplace. As a company, one of our strengths is having the ability to select the most suitable inductive measuring principle and then modifying the sensor to meet the exact needs of an OEM customer. For example, these modifications can include varying the measuring range of the sensor, having integral or separate electronics, changing the mechanical form factor, having the target as a sleeve or plunger in hydraulic cylinders, or providing different mounting options and interfaces. In addition to providing standard LVDT driver electronics, Micro-Epsilon can also provide miniature ASICs for medium to high-volume low-cost applications."

Micro-Epsilon's induSENSOR family of inductive displacement and position sensors includes six core product ranges that are based on the inductive measuring principle, the LVDT (Linear Variable Differential Transformer) principle, or patented variants of these measuring methods.

Conventional three-coil LVDT sensors

The DTA series of LVDT displacement sensors and LVDT gauges have a primary and two secondary coils, which are arranged symmetrically to the primary winding. As a measurement object, a rod-shaped magnetic core can be moved within the differential transformer. Movement of the core within the magnetic field of the coil causes a higher voltage in one secondary coil and a lower voltage in the second coil. The difference between the two secondary voltages is proportional to the core displacement. Due to the differential design of the sensor, the LVDT series has an output signal that is very stable.

Gauge LVDTs with 8mm body diameter and many custom options

The LDR series of inductive sensors are constructed as half-bridge systems rather than the traditional three-coil LVDT design. This enables a short, compact design with smaller diameters. Production costs are therefore lower, which makes the LDR sensors less expensive than LDVTs. Despite the lower cost, technical advantages such as higher operating temperatures, (160degC as standard) and shock rating of up to 300'g' (axial) and 100'g' (radial) are offered with the LDR series.

Inductive-potentiometric sensors LVP and VIP series

The LVP and VIP series of displacement sensors are patented single-coil inductive sensors rather than the three-coil LVDT or two-coil LDR sensor concepts. This offers a significantly improved ratio of measurement range to body length, which means the sensors can be up to 50 per cent shorter for any given measurement ranges. In addition, the sensor body diameter is also significantly reduced, with standard sensors having a diameter of 8mm. The LVP uses an inner core as the sensor rod (like conventional LVDTs), whereas the VIP uses an outer ring as the target, offering an even more compact sensor footprint.

A further advantage of this sensor series is the integrated sensor electronics, which enables the user to have a DC supply and an output in DC volts or 4-20mA current directly from the sensor (remote electronics is also available for OEM applications if preferred).

Chris Jones notes: "Quite often customers are replacing linear potentiometers with LVP sensors, as they offer the simple installation method of a potentiometer, yet are wear-free like LVDTs, giving the user the best features of both technologies."

Long-stroke sensors for hydraulic applications

The EDS series sensors are robust, pressure-resistant position sensors that are designed for hydraulic cylinder positioning in applications where high shock and vibration are likely to be present - such as mobile hydraulic systems in off-highway vehicles, for example. The EDS sensor uses an outer sleeve, as opposed to an inner core, which enables the sensor to be much more robust. In addition, it becomes simpler to install the sensor into the hydraulic cylinder or hydraulic system. Pressure rating of 450bar (higher rating versions are available on request) and 300'g' shock rating (axial) enable these sensors to suit the needs of almost all hydraulic positioning applications.

The sensor does not need remote electronics that must be matched to the sensor; instead the compact electronics are housed in the mounting flange of the sensor, which means the total installation is much more compact than commonly used sensors. It is also possible to adapt the sensor housing to enable is to withstand subsea applications - for example, the sensor can be modified to incorporate a subsea connector or custom mounting flange.

EDS pressure-resistant sensor series

The EDS miniature series is ultra-compact with a diameter of just 3mm, which makes the sensor an excellent choice for miniature hydraulic cylinders and actuators. Although they are very compact, they are still as robust as the standard sensor designs. The sensors are manufactured from a pressure-resistant stainless steel (up to 450bar), can operate to 175degC (or 210degC) and withstand extreme vibration and shock levels (up to 300'g' axial and 100'g' radial). The sensor electronics and signal conditioning are also very compact.

Please follow the link for more information about the induSENSOR series of inductive displacement sensors.