Working the Angles: A magnet rotating
with the arm linked to the chassis (right) turns past a magnetoresistive
sensor on the PCB (left) to measure headlight inclination to the body.
Angle sensor offers Drift-free measurement
The Philips KMZ43T magnetoresistive angle sensor, for contactless measurement of the angle of adjustable automotive headlamps relative to the chassis, uses smaller magnets than the company's previous versions—but provides constant, drift-free performance across a range of temperatures and over the life of the vehicle. The smaller magnet also allows a more compact package for easier placement.
Unlike Hall-effect angle measurement, smaller cheaper ferrite magnets can be used with the thin-film Permalloy magnetoresistive sensor elements that sense the magnetic field lines. These elements are arranged on a single die in two galvanically separated Wheatstone bridges with an angular displacement of 90 degrees. Once above a 30 kA/m threshold of magnetic field strength, the magnetoresistive material senses the direction of the magnetic field lines and relative angle changes. An onboard ASIC is used for signal conditioning and provides digital or analog output, depending on the specific vehicle application.
An advantage of the KMZ43T architecture is the elimination of drift. Hall sensors, which measure signal strength of the magnetic field above 100 kA/m, and thus require more expensive rare earth magnets, drift with changes in signal strength over time or with temperature. But such changes do not have an effect on the direction of the field lines measured magnetoresistively.
Other applications for the angle sensor include x-by-wire functions (steering, and throttle and brake-pedal position), windshield wiper control, and body-angle measurement.
CONTACT:Guenter Reiniger, Philips Semiconductors Tel (248) 848-7600; Fax (513) 671-3363; e-mail: email@example.com://rbi.ims.ca/3843-509
Torque off: The interdigitated
torque-eliminator collars in the OmniSafe fitting prevent twisting of the
sealing glands and metal gasket when the male and female nuts are
tightened together. With linear mating of the fitting halves, galling and
particle generation are mitigated.
Anti-torque fitting cuts contamination
By introducing a torque-eliminating collar between the tightening nut's load bearing shoulder and sealing gland in each half of a patented process-stream fitting, engineers at OmniSafe prevent torque from being transferred to the glands and metal gasket. In previous designs without the collars, this torque could cause galling and particle generation, which could then contaminate a fluid stream. The twisting also stored energy—termed reverse torque or wind up—in the joint that could cause loosening and leaks under shock, vibration, and temperature changes.
Now when the fitting halves are mated, curved tabs on the torque-eliminating collars in both the male and female nuts interdigitate, preventing any twisting load from being transferred to the metal disk seal and the mating glands that grasp it. The glands thus linearly compress the gasket with no rotational sliding of sealing surfaces to generate particles. An industry standard ¼-turn past finger tight is enough to ensure a seal with no reverse torque buildup to loosen the fitting under vibration (MIL-STD-810E).
The torque eliminators are 316L stainless steel to be thermally compatible with the rest of the fitting. The gaskets are stainless or nickel. Depending on size and material, the fittings can operate up to 6,327 psig and temperatures can range down to 4K or up to 700C.
The fittings were originally developed for use in semiconductor manufacturing and the nuclear industry. Applications now include aerospace, where they are used in satellite xenon gas propulsion systems, and test devices such as gas spectrometers and leak-check equipment.
CONTACT:Eric Robinson, OmniSafe Tel (408) 370-3123; Fax (408) 370-3122; e-mail: firstname.lastname@example.org://rbi.ims.ca/3843-510
Silent Rolling: While plastics could have
been used for the end housing to quiet roller noise, nylon had better
performance over time. With action like a toilet paper roller, the
spring-loaded shaft eases assembly.
Nylon bearing housing reduces roller noise
To reduce workplace noise, engineers at Interroll have developed the 1700 Universal Roller Series with bearings mounted in nylon end housings. The free-spinning rollers for gravity conveyors used in materials handling and packaging meet OSHA noise standards (85 dB).
The nylon replaces metal in containing the commercial-grade ball bearings and also damps noise associated with friction and starting resistance. Conveyor Components Product Manager Kim Hagan says, "We looked at other material such as polyethylene and acetal resin which could have damped noise. Nylon was the strongest while not becoming brittle over time."
In addition to steel and stainless steel, roller tubes can be PVC or polyethylene, and come in 1.9, 2.5, 3.15, and 3.5-inch diameters. Bearings can also be stainless for environmentally demanding applications.
CONTACT:Kim Hagan, Interroll Corp. Tel (910) 799-1100; Fax (910) 392-3904; e-mail: email@example.com://rbi.ims.ca/3843-511
Integrated bearing simplifies tractor manufacture
By integrating a steering bearing's inner race into the pivot on which it mounts, Timken engineers not only simplified a previous two-piece configuration (separate bearing and the flanged pivot pin that mounted it) but improved performance and cut customer assembly tasks and costs. The Integrated Steering Pivot (ISP) saves weight and eliminates the time needed for a customer to position the bearing on the pivot, adjust, lube, and seal it before mounting it as a steering king pin for tractor front driving/steering axles. And factory assembly improves sealing and dimensional accuracy.
With a more highly integrated pivot design, the engineers found it possible to increase load capacity. The cage for retaining the tapered roller bearings in the race was changed from steel to a polymer with two extra bearing pockets. The two extra bearings, up from 18 to 20, allow a proportional increase in load capacity without changing the overall size of the bearing.
While such integration brought assembly benefits, the engineers were challenged in providing for adequate induction heat treatment for the cone race and a rib, now part of the pivot. By altering the shape of the coil on the induction heater, they ensured the desired depth of the hardened material profile.
Timken also leveraged developments at Torrington, which it acquired in 2003, by making a Hall position sensor available for angle sensing in the ISP. The sensor is mounted within the core of the pivot and, depending on the application, can be programmed to measure ±24 or ±45 degrees (with an accuracy of ±0.5 degrees). Steering angle output can be used by an operator not only for maneuvering but also in maintaining a straight line for the closest possible crop row spacing. Combined with GPS guidance, sensor readings can help maintain a preplanned course. In the future these technologies can form the basis of autonomous agricultural operations.
CONTACT:Neil Carlson, The Timken Co. Tel (800) 223-1954; e-mail: firstname.lastname@example.org://rbi.ims.ca/3843-512