Mounting of semiconductor sensing means for an electromagnetic tachometer in a portable electric tool
US4385276A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 26, 1981 |
| Grant date | May 24, 1983 |
| Priority date | — |
| Expiry date | Oct 26, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02K11/33
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A counterbalanced rotor is mounted on a rearward extension of the armature shaft of a portable electric tool. The rotor is nested within the annular portion of a ring member which is piloted on the rearward bridge portion of the motor field case. An end cap is secured to the field case and engages the annular portion of the ring, thereby retaining the ring against the bridge on the field case. The annular portion of the ring has an external boss with a notch formed therein substantially tangential to the annular portion. A printed circuit board is received in the notch and carries a semiconductor sensing device, such as a Hall-Effect generator, for cooperation with a magnet carried by the rotor. A spider member is retained in the bridge and has a bearing nested therein for journaling the commutator end of the armature shaft. The spider has a number of openings formed therein. The end cap has a plurality of ventilating openings formed therein, and a fan carried by the armature shaft draws cooling air in through the openings in the end cap. The cooling air is confined by the annular portion of the ring, is subjected to a turbulance by the rotor therein, and flows through the openings…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.