Device for connecting a drill bit to a drill string provided with a penetrometer

Claim 3

A device according to claim 1 wherein during the drilling stage the reaction forces of the ground onto said obturation member have at least one component which maintains said member in position for drilling.

Claim 4

A device according to claim 1 comprising a rigid tubular connector coupled at one end thereof with a drill string and at the other end with the bit, the obturation member having an articulation axis on said connector, a movable mass housed inside said connector, solid with said obturation member, and adapted to cause the rocking of said member to a position of obturation is response to the centrifugal force which moves it away from said connector axis during the rotation of the bit, a stationary mass solid with said connector and ensuring the dynamic balance thereof, and an elastic device interconnecting said masses and ensuring the back motion of said obturation member to an opening position of the bit central bore by bringing said movable mass closer to saId connector axis in the absence of bit rotation.

Claim 5

A device according to claim 1 comprising a rigid tubular connector coupled at one of its ends with a drill string and at its other end with a drill bit, said obturation member having an articulation axis on said connector, a movable mass housed inside said connector, solid with said obturation member and adapted to control the driving of said member to a position of obturation in response to the centrifugal force which moves it away from said connector axis during the rotation of the bit, a stationary mass, solid with said connector and ensuring the dynamic balance thereof, an elastic device interconnecting said masses and ensuring the back motion of said obturation member to a position of free opening of the bit central bore by bringing said movable mass closer to said connector axis in the absence of rotation of the bit, and a drilling fluid distributor secured inside said connector and controlling the irrigation of the bit forehead.

Claim 6

A device according to claim 4 wherein said distributor comprises a cylindrical body having a central bore, said body being housed into said connector and defining an annular space inside the same, said annular space communicating with discharge orifices for the drilling fluid clearing out the cuttings from the forehead, a piston slidably mounted in the central bore of said body and comprising a central duct for the passage of said measuring stem, said piston being maintained through elastic means, for a value of the fluid pressure lower than a predetermined threshold value, to a first position of obturation of said central duct at which the fluid from the drill string is only discharged to said internal annular space, through communication orifices provided through the distributor body, said piston being adapted to be displaced, during the rotation of the bit and in response to a fluid pressure at least equal to said threshold value, against the antagonistic action of said elastic means until it reaches a second position of obturation of said central duct at which the fluid is exclusively discharged into said internal annular space through said communication orifices provided through the distributor body, said piston being displaced, in the absence of rotation of the bit and in response to a fluid pressure at least equal to said threshold value, against the antagonistic action of said elastic means until it reaches a position of obturation of said communication orifices and of free opening of said central duct of the piston, at which the drilling fluid flows exclusively through said central duct, communicating, on the one hand with an orifice for the passage, with a small clearance, of the measuring stem, located at the base of the drill bit connector and, on the other hand with the ducts inclined with respect to the connector axis and adapted to ensure the drilling with fluid jets.

Claim 7

A device according to claim 5, wherein said second position of obturation of said piston central duct, attained during the drill bit rotation and in response to a fluid pressure at least equal to said threshold, is determined by means for limiting the displacement of said piston in the position of the movable mass remote from said connector axis.

Claim 8

A device according to claim 6 wherein said means for limiting said piston displacement comprise complementary elements consisting of a groove and a locking finger, one of said elements being associated with said piston and the other with said movable mass.