Overcenter toggle latch apparatus

A wireline drilling apparatus having an axially extending central axis and being movable axially inwardly through a drill string toward a bit end of the drill string to a position adjacent to the bit end of the drill string to latchingly engage a drill string latch seat and is retractable axially outwardly through the drill string in a direction away from the bit end of the drill string, said drill string having a central axis, comprising:

• an axially elongated latch body having an axially extending central axis, an axial outer end portion and an axial inner end portion;
• a drilling tool mounted to the inner end portion of the latch body;
• an axially extending latch retractor for retracting the latch body, said latch retractor being mounted for limited axial movement relative to the latch body between an axial inner position relative to the latch body and an axial outer relative to the latch body and having an axial outer overshot coupling portion;
• a first latch pivot mounted to the latch body;
• a first latch mounted to the latch pivot for movement between a latch seated position for releasably retaining the latch body in the drill string and a latch release position permitting the latch body being retracted through the drill string, the latch having an axial outer end portion and an axial inner end portion mounted to the latch body by the latch pivot;
• and locking means interconnected between the outer end portion of the latch, the retractor and the latch body for facilitating the movement of the latch to its latch seated position when the latch is axially adjacent to the latch seat in the drill string and after the latch has moved to its latch seated position, to lockingly retain the latch in a latch seated position until the retractor is moved axially outwardly relative to the latch body, and acting in cooperation with the latch retractor for moving the latch from its latch seated position to its latch release position when the latch retractor is moved axially outwardly relative to the latch body and thence retract the latch body through the drill string;
• the latch pivot has a transverse central pivot axis;
• and the locking means includes a first link having a first end and a second end, the second end of the first link being radially inwardly of the first end of the first link when the latch is in its latch seated position, a link first pivot pivotally connecting the first end of the first link to the outer end portion of the latch and having a transverse central axis, and a link second pivot pivotally connecting the second end of the first link to the retractor;
• said link second pivot having a transverse central axis axially inwardly of the central axis of the link first pivot when the locking means lockingly retains the latch in the latch seated position;
• and the central axis of the link second pivot is axially outwardly of the pivot axis of the link first pivot when the latch body is being retracted through the drill string.

A wireline drilling apparatus that has an axial extending central axis and that is movable axially inwardly through a drill string to a position adjacent to the axial inner bit end of the drill string to latchingly engage a drill string latch seat and is retractable axially outwardly through the drill string in a direction away from the bit end of the drill string, comprising:

• an axially elongated latch body having an axially extending central axis, an axial outer end portion and an axial inner end portion;
• a drilling tool mounted to the latch body axial inner end portion;
• an axially extending latch retractor mounted for limited axial movement relative to the latch body between an axial inner position and an axial outer position, said retractor having an axial outer overshot coupling portion;
• a first latch pivot;
• a first latch mounted to the latch body by the latch pivot for movement between a latch seated position for releasably retaining the latch body in the drill string and a latch release position permitting the latch body being retracted through the drill string, the latch having an axial inner end portion pivotally connected to the latch body by the latch pivot and an axial outer end portion;
• and retaining means interconnected between the outer end portion of the latch, the retractor and the latch body for moving the latch to its latch seated position when the latch is axially adjacent to the latch seat in the drill string to retain the latch in a latch seated position once the latch has moved to its latch seated position, and acting in cooperation with the retractor for moving the latch from its latch seated position to its latch release position when the retractor is moved axially outward relative to the latch body and after the latch has been moved from its latch seated position, move the latch body axially outwardly as the retractor is retracted;
• the retaining means including overcenter means operable between a latch locking position to lock the latch in its latch seated position when the retractor is in its axial inner position relative to the latch body and a latch retracted position permitting retraction of latch body through the drill string when the retractor is in its axial outer position relative to the latch body, the overcenter means being connected to the retractor for movement with the retractor and relative to the retractor;
• the overcenter means including a first link having a first end and a second end, the second end of the first link being radially inwardly of the first end of the link and more closely adjacent to the central axis of the latch body than the first end of the first link when the latch is in its latch seated position, limit means for cooperating with the first link when the latch is in its latch seated position for preventing the latch moving to its release position until the retractor is moved axially outwardly relative to the latch body and a first link pivot pivotally connecting the first end of the first link to the outer end portion of the latch for movement with the latch and relative to the latch between a position that the second end of the link is abuttable against the limit means to block movement of the latch from its latch seated position to the latch release position;
• said first link being pivoted relative to the latch when the retractor is moved axially outwardly to pull the latch to its released position;

A wireline drilling apparatus that has an axial extending central axis and that is movable axially inwardly through a drill string to a position adjacent to an axial inner bit end of the drill string to latchingly engage a drill string latch seat and is retractable axially outwardly through the drill string in a direction away from the bit end of the drill string, comprising:

• an axially elongated latch body having an axial outer end portion and an axial inner end portion;
• a drilling tool mounted to the inner end portion of the latch body;
• an axially extending latch retractor mounted for limited axial movement relative to the latch body, said latch retractor having an axial outer overshot coupling portion;
• a first latch pivot having a transverse pivot axis;
• a first latch mounted to the latch body by the latch pivot for movement between a latch seated position for releasably retaining the latch body in the drill string and a latch release position permitting the latch body being retracted through the drill string;
• said latch having an axial outer end portion for latchingly engaging the latch seat and an axial inner end portion pivotally mounted to the latch pivot;
• and interconnecting means interconnected between the latch, the retractor and the latch body for permitting the latch moving to its latch seated position when the latch is axially adjacent to the latch seat in the drill string, and acting in cooperation with the retractor for pulling the latch from its latch seated position to its latch release position when the retractor is moved axially outwardly relative to the latch body;
• the interconnecting means including a first link having a first end and a second end, the second end of the first link being radially inwardly of the first end of the first link and more closely adjacent to the latch body central axis than the first end of the first link when the latch is in its latch seated position, a first link pivot pivotally connecting the first link to the latch for movement with the latch and relative to the latch, the first link pivot having a transverse pivot axis parallel to the latch pivot axis and pivotally connecting the first end of the first link to the latch axially outwardly of the latch pivot, and pivot means for pivotally connecting the second end of the link to the retractor and being moved axially outwardly by the retractor as the retractor is moved axially outwardly relative to the latch body;
• the pivot means having a transverse pivot axis that is parallel to the latch pivot axis and axially inwardly of the pivot axis of the first link pivot when the latch is in the seated position of the latch and axially outwardly of the pivot axis of the first link pivot when the latch is in the release position of the latch.