# US 8,464,807 B2 · Electrical hand tool with magnets for absorbing dust > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,464,807 B2 - Document ID: US8464807B2 - Status: Granted - Kind: B2 - Application number: 12/320,801 - Filed: 2009-02-05 - Published: 2009-09-03 - Granted: 2013-06-18 - Earliest claimed: 2008-02-28 - Assignees: Metabowerke GmbH - Applicants: Markus Johnen; Wolfgang Stickel - Inventors: Markus Johnen; Wolfgang Stickel - Web page: https://patentgrep.com/patent/US8464807B2 ## CPC - B25F 5/008: {Cooling means} - B03C 1/0332: {using permanent magnets} - B03C 1/282: {with associated accumulation indicator, e.g. Hall sensor} - B23Q 11/0064: {by using a magnetic or electric field} - B23Q 11/127: {for cooling motors or spindles} - B24B 23/028: {Angle tools} - H02K 9/06: with fans or impellers driven by the machine shaft - H02K 9/26: Structural association of machines with devices for cleaning or drying cooling medium, e.g. with filters - B03C 2201/32: Checking the quality of the result or the well-functioning of the device - Y02P 70/10: Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working - Y10T 83/242: With means to clean work or tool - B25F: COMBINATION OR MULTI-PURPOSE TOOLS NOT OTHERWISE PROVIDED FOR; DETAILS OR COMPONENTS OF PORTABLE POWER-DRIVEN TOOLS NOT PARTICULARLY RELATED TO THE OPERATIONS PERFORMED AND NOT OTHERWISE PROVIDED FOR {(machines or arrangements of machines for performing specified combinations of different metal-working operations not covered by a single other subclass B23P23/00 and subgroups)} - B03C: MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS (separating isotopes B01D59/00; combinations of magnetic or electrostatic separation with separation of solids by other means B03B, B07B) - B23Q: DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING (tools of the kind used in lathes or boring machines B23B27/00); MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT - B24B: MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING (grinding of gear teeth B23F, of screw-threads B23G1/36; by electro-erosion B23H; abrasive or related blasting B24C; tools for grinding, buffing or sharpening B24D; polishing compositions C09G1/00; abrasives C09K3/14; electrolytic etching or polishing C25F3/00; grinding arrangements for use on assembled railway tracks E01B31/17); DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS - H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53}) - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract An electrical hand tool device comprises a ventilated housing body, which has inlet and outlet openings for cooling air flow and accommodates the electromotive components of the device, in particular, a motor that is excited by a permanent magnet and is powered by a battery, and a magnet that is provided in the area of the cooling air flow for collecting magnetic or magnetizable dust. In order to protect the electric motor, the device is designed in such a fashion that at least two magnets are provided in the axial direction between the inlet openings and the electromotive components of the device, and a means is provided, which electrically cooperates with the at least two magnets to determine whether a substantial amount of magnetizable dust has collected on the magnets, in which case, a control measure can be performed. ## Claims ### Claim 1 An electrical hand tool device of the type having a motor, said device comprising: a ventilated housing having an interior within which the motor is located so as to be exposed to an air flow along a flow path for cooling the motor, said flow path including at least one air inlet opening through which air of said air flow may enter said interior of said housing and at least one air outlet opening through which air of said air flow may exit said interior of said housing; at least two magnets which are separated from one another by at least one gap and are disposed within said housing to form a magnetic field extending across said flow path at a location located downstream of said inlet opening and upstream of the motor for collecting magnetically attractable particles from said air flow to prevent said particles from reaching the motor, said magnets being disposed such that all of said air flow passing through said flow path must pass between said magnets and through said magnetic field before reaching the motor; and means, cooperating with said at least two magnets, for determining whether a substantial amount of said particles has been collected by said magnets and for initiating at least one of: (i) an optically perceivable indication, (ii) an acoustically perceivable indication and (iii) de-energizing the motor. ### Claim 2 (depends on 1) An electrical hand tool device as claimed in claim 1, wherein said means determines whether there is electric contact between said magnets. ### Claim 3 (depends on 1) An electrical hand tool device as claimed in claim 1 wherein said control measure includes switching off the device. ### Claim 4 (depends on 1) An electrical hand tool device as claimed in claim 1, wherein said housing body can be opened for cleaning said magnets. ### Claim 5 (depends on 1) An electrical hand tool device as claimed in claim 1, wherein said magnets can be removed from said housing body. ### Claim 6 (depends on 1) An electrical hand tool device as claimed in claim 1, wherein said housing body includes an insertion receptacle within which said magnets are removably disposed such that said magnets can be removed from said insertion receptacle if said housing body is opened. ### Claim 7 (depends on 6) An electrical hand tool device as claimed in claim 6, wherein said magnets are loaded by a spring. ### Claim 8 (depends on 1) An electrical hand tool device as claimed in claim 1, wherein said magnets are substantially C-shaped, as viewed in cross-section, perpendicularly to a longitudinal direction of said housing body. ### Claim 9 (depends on 1) An electrical hand tool device as claimed in claim 1, wherein said magnets peripherally surround a portion of said flow path. ### Claim 10 (depends on 1) An electrical hand tool device as claimed in claim 1, wherein said means comprises a circuit.