# US 11,110,581 B2 · Coil spacing > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,110,581 B2 - Document ID: US11110581B2 - Status: Granted - Kind: B2 - Application number: 16/466,715 - Filed: 2017-11-09 - Published: 2019-10-10 - Granted: 2021-09-07 - Earliest claimed: 2016-12-09 - Assignees: Hilti Aktiengesellschaft - Applicants: Hilti Aktiengesellschaft - Inventors: Konrad Artmann; Thomas Schaefer; Markus Hartmann; Norbert Daam - Web page: https://patentgrep.com/patent/US11110581B2 ## CPC - B25D 17/20: Devices for cleaning or cooling tool or work - B25D 11/064: {using an electromagnetic drive} - B25D 16/00: Portable percussive machines with superimposed rotation {, the rotational movement of the output shaft of a motor being modified to generate axial impacts on the tool bit (combined percussion and rotary drilling adapted for earth drilling E21B6/00)} - H02K 3/24: with channels or ducts for cooling medium between the conductors - H02K 7/145: {Hand-held machine tool} - H02K 9/02: by ambient air flowing through the machine - H02K 9/06: with fans or impellers driven by the machine shaft - H02K 33/12: with armatures moving in alternate directions by alternate energisation of two coil systems - B25D 2217/0061: related to cooling - B25D 2250/145: Electro-magnetic parts - H02K 2213/03: Machines characterised by numerical values, ranges, mathematical expressions or similar information - B25D: PERCUSSIVE TOOLS {(percussive machines for forging B21J; hand-held drilling machines, in general B23B45/00, for wood B27C3/08; drilling machines, used for mining or quarrying, with reciprocating tool which is turned intermittently when out of contact with the working face E21B1/00)} - H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53}) ## Abstract A power tool (1) is provided, especially a hammer drill and/or a chiseling hammer drill, including a percussive mechanism (12) with a percussive element (13) to generate a percussive pulse onto a tool (1), the element being reversibly movable along a longitudinal axis (R) by a magnetic field in order to generate the percussive pulse, and including at least a first and a second coil device (1, 2) to generate the magnetic field. Each coil device (1, 2) has at least a first coil ring (3) with a first radius (R1) and a second coil ring (4) with a second radius (R2), whereby the first radius (R1) of the first coil ring (3) is greater than the second radius (R2) of the second coil ring (4), so that a space (S) is formed, at least in certain areas, between the at least first and second coil rings (3, 4), whereby a fluid (L), especially an air stream, that serves to cool the coil device (1, 2) can flow through the space. ## Claims ### Claim 1 A power tool comprising: a percussive mechanism with a percussive element to generate a percussive pulse onto a tool, the percussive element being reversibly movable along a longitudinal axis by a magnetic field in order to generate the percussive pulse; and at least a first and a second coil device to generate the magnetic field, each of the first and second coil devices having at least a first coil ring with a first radius and a second coil ring with a second radius, whereby the first radius of the first coil ring is greater than the second radius of the second coil ring, so that a space is formed, at least in certain areas, between the at least first and second coil rings, a fluid serving to cool the first and second coil devices flowable through the space; wherein the first and second coil rings are arranged with respect to each other in such a way that the distance between an upper end of an uppermost coil ring and a lower end of a lowermost coil ring of the first and second coil rings is greater than a sum of a first height of the uppermost coil ring and of a second height of the lowermost coil ring. ### Claim 2 (depends on 1) The power tool as recited in claim 1 wherein the first or second coil device has more than the first and second coil ring so that a plurality of corresponding spaces are present between the individual coil rings, at least in certain areas. ### Claim 3 (depends on 1) The power tool as recited in claim 1 wherein the first and second coil rings are arranged in a vertical plane. ### Claim 4 (depends on 1) The power tool as recited in claim 1 wherein each of the first and second coil rings has a maximum of two to fourteen winding layers of an electric conductor. ### Claim 5 (depends on 4) The power tool as recited in claim 4 wherein each of the first and second coil rings has a maximum of seven or eight winding layers of an electric conductor. ### Claim 6 (depends on 1) The power tool as recited in claim 1 wherein the space between the first and second coil rings has a height of 2 mm to 10 mm. ### Claim 7 (depends on 1) The power tool as recited in claim 1 wherein the fluid is an air stream. ### Claim 8 (depends on 1) A method for operating the power tool as recited in claim 1 comprising flowing the fluid through the space. ### Claim 9 (depends on 1) A hammer drill comprising the power tool as recited in claim 1. ### Claim 10 (depends on 1) A chiseling hammer drill comprising the power tool as recited in claim 1. ### Claim 11 (depends on 1) The power tool as recited in claim 1 further comprising a sleeve, the first coil ring and the second coil ring being positioned around the sleeve. ### Claim 12 (depends on 11) The power tool as recited in claim 11 wherein the percussive element is positioned inside the sleeve. ### Claim 13 (depends on 12) The power tool as recited in claim 12 further comprising a spring at a rear end of the sleeve serving to brake and return the percussive element. ### Claim 14 (depends on 13) The power tool as recited in claim 13 further comprising an intermediate striking pin element between the tool and the percussive element. ### Claim 15 (depends on 13) The power tool as recited in claim 13 wherein the spring is a helical spring. ### Claim 16 (depends on 1) The power tool as recited in claim 1 further comprising a tool socket between the percussive mechanism and the tool, the tool socket for holding the tool socket. ### Claim 17 (depends on 16) The power tool as recited in claim 16 wherein further the tool socket is arranged coaxially with the percussive mechanism. ### Claim 18 (depends on 1) The power tool as recited in claim 1 further comprising an intermediate striking pin element between the tool and the percussive element. ### Claim 19 (depends on 1) The power tool as recited in claim 1 further comprising a fan for generating flow of the fluid.