Well drilling tool

A well drilling tool adapted to be connected to the lower end of a drill string above the drill bit, whereby drilling fluid may be circulated downwardly through the inside of the tool and upwardly within the annulus between the outside of the tool and the bore of the well being drilled, comprising a shaft member having means thereon for connecting it to the bit, a tubular member arranged concentrically of the shaft member to provide an annular space therebetween, means on the members within said space supporting one of the shaft and tubular members from the other of the shaft and tubular members for rotation with respect thereto, means on said other of the shaft and tubular members for connecting it to the lower end of the drill string, first means sealing between said members for separating the fluid on one side of said tool from that within a portion of said space, means providing a lubricant chamber including second and third sealing means between said members within the space portion, and means fluidly connecting the other side of the tool with said space portion above and below said second and third sealing means, respectively, whereby said first seal member is adapted to contain the pressure differential between the inner and outer sides of the tool, and said second and third sealing means separate the part of the chamber between them from the fluid on said other side of the tool, said means providing the chamber including means for varying its volume in response to changes in the pressure of fluid on said other side of the tool near said chamber, so as to maintain the pressure of lubricant within the chamber substantially equal to that on said other side of the tool, and thereby protect parts contained within said chamber from said drilling fluid.

A well drilling tool adapted to be connected to the lower end of a drill string above the drill bit, whereby drilling fluid may be circulated downwardly through the inside of the tool and upwardly within the annulus between the outside of the tool and the bore of the well being drilled, comprising a shaft member having means thereon for connecting it to the bit, a tubular member arranged about the shaft member to provide an annular space therebetween, means on the tubular member for connecting it to the lower end of the drill string, means on the members within said space supporting the shaft member from the tubular member for rotation with respect thereto, first means sealing between said members for separating the fluid on one side of said tool from that within a portion of said space, means providing a lubricant chamber including second and third sealing means between said members within the space portion above and below the supporting means, and means fluidly connecting the other side of the tool with said space portion above and below said second and third sealing means, respectively, whereby said first seal means is adapted to contain the pressure differential between the inner and outer sides of the tool, and said second and third sealing means separate the part of the chamber between them from the fluid on said other side of the tool, said means providing the chamber including means for varying its volume in response to changes in the pressure of fluid on said other side of the tool near said chamber, so as to maintain the pressure of lubricant within the chamber substantially equal to that on said other side of the tool, and thereby protect parts contained within said chamber from said drilling fluid.

A well drilling tool adapted to be connected to the lower end of a drill string above the drill bit, whereby drilling fluid may be circulated downwardly through the inside of the tool and upwardly within the annulus between the outside of the tool and the bore of the well being drilled, comprising a shaft member having means thereon for connecting it to the bit, a tubular member arranged about the shaft member to provide an annular space therebetween, means on the tubular member for connecting it to the lower end of the drill string, means on the members within said space supporting the shaft member from the tubular member for rotation with respect thereto, first means sealing between said members above the supporting means for separating the fluid on the inner side of said tool from that within a portion of said space, means providing a lubricant chamber including second and third sealing means between said members within the space portion above and below the supporting means, and means fluidly connecting the outer side of the tool with said space portion above and below said second and third sealing means, respectively, whereby said first seal means is adapted to contain the pressure differential between the inner and outer sides of the tool, and said second and third sealing means separate the part of the chamber between them from the fluid on said outer side of the tool, said means providing the chamber also including an annular passageway within the shaft member fluidly connected at its lower end with said outer side of the tool, and an annular piston sealably slidable within the passageway for varying the volume of said chamber in response to changes in the pressure of fluid on said outer side of the tool near said chamber, so as to maintain the pressure of lubricant within the chamber substantially equal to that on said outer side of the tool, and thereby protect the supporting means contained within said chamber from said drilling fluid.