Magnetic shear locking methods and apparatus

In a method of operating an electromagnetic lock including an energizable first part having a magnetic pole face and a second part magnetically attractable to said pole face arranged for shearing relative motion parallel to said pole face, the improvement comprising in combination the steps of:

• providing in one of said first and second parts a protrusion toward the other of said first and second parts;
• providing in said other part a recess corresponding to said protrusion;
• initially spacing said first and second parts away from each other by a distance exceeding said protrusion to permit relative sideways motion between said first and second parts;
• and
• interfitting said protrusion and corresponding recess by magnetic attraction upon energization of said first part and movement of said first and second parts toward each other;
• constituting said protrusion as a non-magnetic separation between said first and second parts so as to enable said second part to cross said first part even after energization of said first part until said protrusion and corresponding recess are interfitted.

In a method of operating an electromagnetic lock for a door structure having a stationary part defining a door opening and a movable part for selectively opening and closing said door opening, with said electromagnetic lock including a first part having a magnetic pole face and a second part magnetically attractable to said pole face, the improvement comprising in combination the steps of:

• providing with the aid of non-magnetic material a surface inclined relative to said pole face;
• mounting one of said first and second parts of said lock on one of said stationary and movable parts of said door structure;
• mounting the other of said first and second parts of said lock on the other of said stationary and movable parts of said door structure for shearing relative motion between said first and second parts of said lock parallel to said pole face upon movement of said movable part;
• closing said door opening with said movable part of the door structure;
• locking said movable part of the door structure in said door opening by exerting magnetic attraction with said first on said second part of the lock by means of a magnetic field generating a predetermined holding power between said first and second parts;
• permitting an attempt to move said movable part of the door structure while said first part exerts magnetic attraction on said second part of the lock and translating shearing motion between said first and second parts of the lock with the aid of said inclined surface into a lifting force tending to lift said second part away from said first part of the lock;
• and
• resisting said attempt to move said movable part of the door structure by providing between said first and second parts a holding power exceeding said predetermined holding power by countering said shearing motion with an opposition of said lifting force by said magnetic attraction and a mechanical friction between said first and second parts upon attempted shearing motion therebetween.

In a method of operating an electromagnetic lock for a door structure having a stationary part defining a door opening and a movable part for selectively opening and closing said door opening, with said electromagnetic lock including an energizable first part having a magnetic pole face and a second part magnetically attractable to said pole face, the improvement comprising in combination the steps of:

• providing in one of said first and second parts of the lock a protrusion toward the other of said first and second parts;
• providing in said other parts of the lock of a recess corresponding to said protrusion;
• mounting one of said first and second parts of the lock on one of said stationary and movable parts of the door structure;
• mounting the other of said first and second parts of the lock on the other of said stationary and movable parts of the door structure for shearing relative motion between said first and second parts of the lock parallel to said pole face upon movement of said movable part of the door structure;
• initially spacing said first and second parts of the lock away from each other by a distance exceeding said protrusion to permit movement of said movable part of the door structure;
• locking said movable part of the door structure in said door opening by interfitting said protrusion and corresponding recess by magnetic attraction upon energization of said first part and movement of said first and second parts toward each other;
• and
• constituting said protrusion as a non-magnetic separation between said first and second parts so as to enable said second part to cross said first part during closing of said door opening by said movable part even after energization of said first part until said protrusion and corresponding recess are interfitted.

In an electromagnetic lock including an energizable first part having a magnetic pole face and a second part magnetically attractable to said pole face arranged for shearing relative motion parallel to said pole face, the improvement comprising in combination:

• a protrusion in one of said first and second parts toward the other of said first and second parts;
• a recess in said other part corresponding to said protrusion;
• means for initially spacing said first and second parts away from each other by a distance exceeding said protrustion to permit relative sideways motion between said first and second parts;
• and
• means for interfitting said protrusion and corresponding recess by magnetic attraction upon energization of said first part and movement of said first and second parts toward each other;
• said protrusion being of non-magnetic material for enabling said second part to cross said first part even after energization of said first part, until said protrusion and corresponding recess are interfitted.

In an electromagnetic lock for a door structure having a stationary part defining a door opening and a movable part for selectively opening and closing said door opening, with said electromagnetic lock including a first part having a magnetic pole face and a second part magnetically attractable to said pole face by means of a magnetic field generating a predetermined holding power between said first and second parts, said first and second parts being arranged for shearing relative motion parallel to said pole face, the improvement comprising in combination:

• means for mounting one of said first and second parts of said lock on one of said stationary and movable parts of said door structure;
• means for mounting the other of said first and second parts of said lock on the other of said stationary and movable parts of said door structure for shearing relative motion between said first and second parts of said lock parallel to said pole face upon movement of said movable part;
• non-magnetic means coupled to said first and second parts of the lock and having a surface inclined relative to said pole face for translating shearing motion between said first and second parts of the lock into a lifting force tending to lift said second part away from said first part of the lock;
• and
• means for providing between said first and second parts a holding power exceeding said predetermined holding power, including means connected to said first part for magnetically attracting said first and second parts to each other in opposition to said lifting force and for countering said lifting force with said magnetic attraction and a mechanical friction between said first and second parts upon attempted shearing motion therebetween.

In an electromagnetic lock for a door structure having a stationary part defining a door opening and a movable part for selectively opening and closing said door opening, with said electromagnetic lock including an energizable first part having a magnetic pole face and a second part magnetically attractable to said pole face, the improvement comprising in combination:

• a protrusion in one of said first and second parts of the lock toward the other of said first and second parts;
• a recess in said other part of the lock corresponding to said protrusion;
• means for mounting one of said first and second parts of the lock on one of said stationary and movable parts of the door structure;
• means for mounting the other of said first and second parts of the lock on the other of said stationary and movable parts of the door structure for shearing relative motion between said first and second parts of the lock parallel to said pole face upon movement of said movable part of the door structure;
• means for initially spacing said first and second parts of the lock away from each other by a distance exceeding said protrusion to permit movement of said movable part of the door stucture;
• and
• means for locking said movable part of the door structure in said door opening by interfitting said protrusion and corresponding recess by magnetic attraction upon energization of said first part and movement of said first and second parts toward each other;
• said protursion being of non-magnetic material for enabling said second part to cross said first part even after energization of said first part, until said protrusion and corresponding recess are interfitted.

In a method of operating an electromagnetic lock including a first part having a magnetic pole face and a second part magnetically attractable to said pole face arranged for shearing relative motion parallel to said pole face, the improvement comprising in combination the steps of:

• providing in one of said first and second parts a protrusion toward the other of said first and second parts;
• making said protrusion to be stationary on said one of said first and second parts;
• providing in said other part a recess corresponding to said protrusion;
• initially spacing said first and second parts away from each other by a distance exceeding said protrusion to permit relative sideways motion between said first and second parts;
• interfitting said protrusion and corresponding recess by magnetic attraction and movement of said first and second parts toward each other;
• terminating said magnetic attraction;
• and
• tilting one of said first and second parts relative to the other of said first and second parts to clear said protrusion for relative sideways motion between said first and second parts.