R+W couplings from RR Fisher & Co Ltd were operated at 120,000 RPM without transmitting any vibration to the test stand in a recent client application involving functional testing of turbo-chargers.
Turbo-chargers are used with gasoline or diesel motors in automobiles and light utility vehicles. A fully automatic functional test is performed on exhaust turbo-chargers to ensure they operate without problems.
The test stand designed for this purpose challenged R+W engineers with diverse requirements:
- Torsion rigid, backlash-free coupling with a maximum torque of 2 Nm
- The coupling needed to compensate an axial offset of 1mm, lateral offset of 0.25mm and angular offset of 2°
- High rotary speed of 120,000 RPM
Metal bellows couplings have very high torsional rigidity in the direction of rotation, which ensures the coupling only twists minimally when subjected to torque load. Torsion angle is generally less than 0.05 degrees.
The right connection for the drive train was found among the coupling connection types available from R+W such as clamping hub, flange, conical sleeve and expanding mandrel.
The applicable know-how gained from previous test stand projects involving couplings at such high rotary speeds was already available to R+W engineers.
The coupling was balanced on a 2-plane horizontal balancing machine to G1 accuracy. This permits the coupling to be operated at the 120,000 RPM speed requested by the customer without passing vibrations through the coupling into the test stand.
Exhaust turbo-charger bearings are checked on the test stand. The coupling is located between the test object and the drive mechanism to connect the drive and test object shafts.