# US 2008/0185922 A1 · Electric Drive Unit For Generating An Oscillating Displacement > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0185922 A1 - Document ID: US20080185922A1 - Status: Published application - Kind: A1 - Application number: 10/577,203 - Filed: 2004-10-23 - Published: 2008-08-07 - Earliest claimed: 2003-10-29 - Assignees: Braun GmbH - Inventors: Gerhard Kressner; Alexander Schroter; Christian Junk; Peter Hilfinger; Hansjorg Reick; Bernhard Kraus; Uwe Schober - Web page: https://patentgrep.com/patent/US20080185922A1 ## CPC - H02K 33/02: with armatures moved one way by energisation of a single coil system and returned by mechanical force, e.g. by springs - A61C 17/225: {Handles or details thereof} - B26B 19/28: Drive layout for hair clippers or dry shavers, e.g. providing for electromotive drive (electric motors per se H02) - A61C 17/34: driven by electric motor - H02K 1/34: Reciprocating, oscillating or vibrating parts of the magnetic circuit - Y10T 29/49009: Dynamoelectric machine - H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53}) - A61C: DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE (non-driven toothbrushes A46B; {tongue scrapers A61B17/24;} preparations for dentistry A61K6/00; preparations for cleaning the teeth or mouth A61K8/00, A61Q11/00) - B26B: HAND-HELD CUTTING TOOLS NOT OTHERWISE PROVIDED FOR (for harvesting A01D; for horticulture, for forestry A01G; for butchering or meat treatment A22; for manufactering or repairing footwear A43D; nail clippers or cutters A45D29/02; kitchen equipment A47J; {vegetable slicers, julienne cutters and similar devices and holders therefor, B26D3/28}; for surgical purposes A61B; for metal B23D; cutting by abrasive fluid jets B24C5/02; plier-like tools with cutting edges B25B7/22; pincers B25C11/02; handles for hand implements, in general B25G; guillotine-type cutters B26D; {perforating by non-mechanical means, e.g. by fluid jet, B26F1/26}; for erasing B43L19/00; for textile materials D06H) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract An electric drive unit for generating an oscillating movement, having a stator, a rotor, a torsion element and a tuning element. The tuning element acts upon the torsion element and serves to mechanically tune the resonant frequency of the drive unit. ## Claims ### Claim 1 An electric drive unit for generating an oscillating movement, the drive unit comprising: a stator; a rotor; a torsion element; and a tuning element, which acts upon the torsion element and serves for mechanically tuning the resonant frequency of the drive unit, wherein the rotor comprises a hollow shaft, and wherein the torsion element is at least partially arranged within the hollow shaft. ### Claim 2 (depends on 1) The drive unit according to claim 1, wherein the tuning element is arranged to secure the torsion element in a selectable position. ### Claim 3 (depends on 2) The drive unit according claim 2, wherein the tuning element is arranged on the stator such that it can be displaced and fixed in position. ### Claim 4 (depends on 3) The drive unit according to claim 3, wherein the tuning element is displaceable parallel to the longitudinal axis of the drive unit. ### Claim 5 (depends on 3) The drive unit according to claim 3, wherein the tuning element engages into at least one groove in the stator. ### Claim 6 (depends on 1) The drive unit according to claim 1, wherein the tuning element comprises a clamping device. ### Claim 7 (depends on 6) The drive unit according to claim 6, wherein the tuning element comprises two parts and at least one connecting element configured to draw the two parts together. ### Claim 8 (depends on 1) The drive unit according to claim 1, wherein the torsion element is fixed on the rotor. ### Claim 9 (depends on 1) The drive unit according to claim 1, wherein the torsion element comprises a torsion rod. ### Claim 10 (depends on 1) The drive unit according to claim 1, further comprising a housing having a recess arranged to accommodate the tuning element. ### Claim 11 (depends on 1) The drive unit according to claim 1, wherein the stator comprises permanent magnets and at least one coil. ### Claim 12 (depends on 1) The drive unit according to claim 1, wherein the rotor comprises an armature of a magnetizable material. ### Claim 13 (depends on 1) A small electric appliance, comprising drive unit of claim 1. ### Claim 14 (depends on 13) The small appliance of claim 13, in the form of an electric toothbrush or an electric razor. ### Claim 15 A method of manufacturing an electric drive unit for generating an oscillating movement, wherein the drive unit comprises a stator, a rotor, a torsion element and a tuning element, and wherein the resonant frequency of the drive unit is mechanically tuned, the method comprising: exciting the drive unit to generate an oscillating movement; and determining from the oscillating movement a desired location on the torsion element for securing the tuning element to tune a resonant frequency of the drive unit. ### Claim 16 (depends on 15) The method of claim 15, further comprising fixing the torsion element on the tuning element in the desired location. ### Claim 17 (depends on 16) The method according to claim 16, wherein exciting the drive unit comprises exciting the drive unit by pulses. ### Claim 18 (depends on 15) The method according to claim 15, further comprising switching the drive unit off, and then fixing the torsion element a rotational position that the rotor assumes when the drive unit is switched off.