# US 2017/0256349 A1 · Plunger for magnetic latching solenoid actuator > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0256349 A1 - Document ID: US20170256349A1 - Status: Published application - Kind: A1 - Application number: 15/449,335 - Filed: 2017-03-03 - Published: 2017-09-07 - Earliest claimed: 2016-03-04 - Assignees: Johnson Electric S.A. - Applicants: Johnson Electric S.A. - Inventors: Richard Anthony CONNELL - Web page: https://patentgrep.com/patent/US20170256349A1 ## CPC - H01F 7/1615: {Armatures or stationary parts of magnetic circuit having permanent magnet} - H01F 7/121: Guiding or setting position of armatures, e.g. retaining armatures in their end position - H01F 7/13: characterised by pulling-force characteristic - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES ## Abstract A plunger includes an elongate plunger body which is at least in part cylindrical and a plunger head at one end of the plunger body. The plunger body has a magnet-interface body portion which has a non-cylindrical cross-section perpendicular to a longitudinal axis of the plunger body. A magnetic latching solenoid actuator using such a plunger is also provided, as is a method of improving the performance of a magnetic latching solenoid actuator. ## Claims ### Claim 1 A plunger for a magnetic latching solenoid actuator, the plunger comprising: an elongate plunger body; and a plunger head at one end of the plunger body; the plunger body having a magnet-interface body portion which defines first and second planar surfaces on opposite lateral sides of the plunger body. ### Claim 2 (depends on 1) The plunger as claimed in claim 1, wherein the magnet-interface body portion has a square or rectangular said cross-section. ### Claim 3 (depends on 1) The plunger as claimed in claim 1, wherein the magnet-interface body portion is spaced from the plunger head. ### Claim 4 (depends on 1) The plunger as claimed in claim 1, wherein the magnet-interface body portion is spaced from an end of the plunger body which is opposite the plunger head. ### Claim 5 (depends on 1) The plunger as claimed in claim 1, wherein the plunger body is at least in part cylindrical adjacent to the magnet-interface body portion. ### Claim 6 (depends on 1) The plunger as claimed in claim 1, wherein the magnet-interface body portion has a greater cross-sectional area than that of a remainder of the plunger body. ### Claim 7 (depends on 1) The plunger as claimed in claim 1, wherein the magnet-interface body portion extends along at least a majority of a longitudinal extent of the plunger body. ### Claim 8 (depends on 7) The plunger as claimed in claim 7, wherein the magnet-interface body portion extends along the entirety of the longitudinal extent of the plunger body. ### Claim 9 (depends on 7) The plunger as claimed in claim 7, wherein the magnet-interface body portion has a uniform or substantially uniform width along the longitudinal extent of the plunger body. ### Claim 10 A magnetic latching solenoid actuator comprising: a solenoid coil; a magnetisable solenoid core mounted within the solenoid coil; a magnet element mounted at or adjacent to an end of the solenoid coil; and a plunger having a magnet-interface body portion magnetically engagable with the magnet element, the plunger being receivable by the solenoid coil such that at least part of the magnet-interface body portion is adjacent to the magnet element, the magnet-interface body portion being complementarily-shaped to the magnet element to increase or optimise a magnetic engagement therebetween. ### Claim 11 (depends on 10) The magnetic latching solenoid actuator as claimed in claim 10, wherein an extent of the plunger which is receivable within the solenoid coil is cylindrical. ### Claim 12 (depends on 11) The magnetic latching solenoid actuator as claimed in claim 11, wherein the solenoid coil is a cylindrical coil. ### Claim 13 (depends on 10) The magnetic latching solenoid actuator as claimed in claim 10, wherein the magnet-interface body portion of the plunger is sized so as to be unable to enter the solenoid coil. ### Claim 14 (depends on 10) The magnetic latching solenoid actuator as claimed in claim 10, wherein the magnet-interface body portion of the plunger has a square or rectangular cross-section. ### Claim 15 (depends on 10) The magnetic latching solenoid actuator as claimed in claim 10, wherein the magnet-interface body portion forms at least a majority of a longitudinal extent of a body of the plunger, the magnet-interface body portion having a square or rectangular cross-section. ### Claim 16 (depends on 15) The magnetic latching solenoid actuator as claimed in claim 15, wherein the solenoid coil is a square or rectangular coil. ### Claim 17 (depends on 10) The magnetic latching solenoid actuator as claimed in claim 10, wherein the solenoid core forms a plunger stop. ### Claim 18 (depends on 10) The magnetic latching solenoid actuator as claimed in claim 10, wherein the magnet element comprises first and second bar magnets. ### Claim 19 (depends on 10) The magnetic latching solenoid actuator as claimed in claim 10, wherein the magnet element is formed as a magnet housing having a square bore therethrough which is dimensioned to accommodate the magnet-interface body portion of the plunger. ### Claim 20 A method of improving the performance of a magnetic latching solenoid actuator, the method comprising the step of improving a magnetic interaction between a plunger and a magnet element of the magnetic latching solenoid actuator by modifying a cross-section of the plunger at or adjacent to the magnet element so as to be more square or rectangular so as to better match a shape of the magnet element.