Magnetic latch mechanism and method particularly for trailer brakes

A mono-stable magnetic latch mechanism having a stable latched first condition, an unstable and magnetic flux-forced unlatched second condition and a modulatable range of operation between said first and second conditions and including said second condition, said mechanism comprising:

• a first member, a fixed member, a movable member movable relative to said fixed member and said first member, and a magnetic array forming a part of said first member;
• said magnetic array having at least one permanent magnet and at least one electromagnet which is normally electromagnetically deenergized, the magnetic flux only of said at least one permanent magnet holding said magnetic array in said stable latched condition wherein said magnetic array is magnetically latched with said movable member;
• and control means for said magnetic array selectively controlling the energization of said at least one electromagnet to a predetermined magnetic flux level from its normally deenergized state in modulated stages, said control means having manipulatable magnetic flux strength-and-polarity-controlling characteristics selectively moving said magnetic array into and within said range of operation between said first and second conditions by controlling the amount and polarity of energization of said at least one electromagnet to selectively degrade, neutralize or overpower the magnetic flux of said at least one permanent magnet and thereby to selectively degrade the effective magnetic latching force of said permanent magnet latching said magnetic array to said movable member, neutralize the effective magnetic latching force of said permanent magnet latching said magnetic array to said movable member, and overpower the magnetic latching force of said permanent magnet latching said magnetic array to said movable member by reversing the effective magnetic force of said magnetic array and repelling said magnetic array away from said movable member.

The method of selectively and alternatively magnetically latching and unlatching a first member to and from a second member, said method comprising the steps of:

• (1) providing a magnetic-flux-conductive part of the second member;
• (2) establishing a permanent magnetic flux within a part of the first member;
• (3) magnetically latching the first member to the second member by only the permanent magnetic flux within a part of the first member;
• (4) selectively establishing, modulating and disestablishing an electromagnetic magnetic flux within a part of the first member which when established is in magnetic flux interactive relation with the permanent magnetic flux, the electromagnetic flux when established being selectively of predetermined first or second magnetic polar orientations;
• (5) the electromagnetic magnetic flux, when having the first magnetic polar orientation established, modifying the effect of the permanent magnetic flux so the net effective magnetic flux magnetically decreases the magnetic attraction of the first member to the second member;
• (6) then further modifying the effect of the permanent magnetic flux by the electromagnetic flux so the net effective magnetic flux is such that the magnetic attraction of the first member to the second member is eliminated, causing the first member to be magnetically unlatched from the second member;
• (7) then maintaining sufficient electromagnetic flux within the part of the first member to keep the first member unlatched from the second member;
• (8) then modulating a decrease of the electromagnetic flux within the part of the first member so that the net effective magnetic flux permits and upon the magnetic and operable physical engagement of the first member with the magnetic-flux-conductive part of the second member further modulating the effective magnetic flux force of the part of the first member acting to keep that member part engaged with the second member, and controlling the desired extent of the magnetic latching attraction of the part of the first member to the second member;
• (9) and when full force magnetic latching of the part of the first member to the second member is desired, disestablishing the electromagnetic flux and reestablishing the permanent magnetic flux as the only active magnetic flux, the permanent magnetic flux then having a full strength completed magnetic flux circuit through the magnetic-flux-conductive part of the second member and the part of the first member in which the permanent magnetic flux is established.