Ball screw and nut mechanism

Claim 2

A ball screw and nut mechanism for converting a movement of rotation into a movement of translation or vice versa, comprising a screw member and a nut member each having at least one first and one second helical groove of same pitch, one of said grooves axially shifted relative to the other, the first grooves of said members defining a first helical channel having a predetermined cross-section, and the second grooves forming a helical recirculation channel having substantially larger predetermined cross-section, a train of balls for movement in said first channel, said balls having size congruent to the cross-section of said first channel to permit transmission of force between the members, and means for transferring said balls from each end of said first helical channel into the corresponding end of the helical re-circulation channel and vice versa, whereby the balls arriving at one end of said first channel are permitted to freely circulate through said helical re-circulation channel, then are transferred to the other end of said first channel.

Claim 3

Mechanism as set forth in claim 1, wherein each end of the first helical groove of said nut member is connected to the corresponding end of the second helical groove of said nut member through a passage formed in said nut member.

Claim 4

A re-circulating bAll, screw and nut apparatus operable with a plurality of balls having first diameter, comprising cooperating screw and nut members having adjacent mating surfaces, wherein rotary motion of one of said members relative to the other causes axial motion of the other member, each of said members having defined in its mating surface a first helical groove having a predetermined pitch and having top and bottom ends and a second similar helical groove of the same pitch and shifted axially relative to the first groove by a fraction of said pitch, said first groove of the nut being adjacent a portion of the first groove of the screw member and forming between them a drive channel of diameter congruent with said first diameter for transmission of force between said members when balls are in said drive channel, and said second groove of the nut being adjacent a portion of the second groove of the screw and forming between them a re-circulation channel having second diameter greater than said first diameter, said nut member further comprising a top transfer channel having diameter at least equal to said first diameter and extending only in said nut''s mating surface and between and connecting the top ends of the first and second grooves in said nut, and a bottom transfer channel having diameter at least equal to said first diameter and extending only in said nut''s mating surface and between and connecting the bottom ends of said first and second grooves in the nut, said drive, re-circulation top, and bottom channels forming a continuous passage, whereby during rotation of one of said members relative to the other, said balls are movable in the drive channel, to and through one transfer channel to said re-circulation channel, and thence to and through the other transfer channel.

Claim 5

A re-circulating bAll, screw and nut apparatus operable with a plurality of balls having first diameter, comprising cooperating screw and nut members having adjacent mating surfaces, wherein rotary motion of one of said members relative to the other causes axial motion of the other member, each of said members having defined in its mating surface a first helical groove having a predetermined pitch and having top and bottom ends and a second similar helical groove of the same pitch and shifted axially relative to the first groove by a fraction of said pitch, said first groove of the nut being adjacent a portion of the first groove of the screw member and forming between them a drive channel of diameter congruent with said first diameter for transmission of force between said members when balls are in said drive channel, and said second groove of the nut being adjacent a portion of the second groove of the screw and forming between them a re-circulation channel having second diameter greater than said first diameter, said nut member further comprising a top transfer channel having diameter at least equal to said first diameter and extending only in said nut''s mating surface and between and connecting the top ends of the first and second grooves in said nut, and a bottom transfer channel having diameter at least equal to said first diameter and extending only in said nut''s mating surface and between and connecting the bottom ends of said first and second grooves in the nut, said drive, re-circulation top, and bottom channels forming a continuous passage, whereby during rotation of one of said members relative to the other, said balls are movable in the drive channel, to and through one transfer channel to said re-circulation channel, and thence to and through the other transfer channel.

Claim 6

Apparatus according to claim 3 wherein said top transfer channel comprises first and second sections, the first section having a first end opening into the top end of said first groove, and a second end, the second section extending generally parallel with said nut axis, and interconnecting said second end of the first section and the top end of said second groove, and said bottom transfer channel being similar to the top transfer channel connecting said bottom ends of said first and second grooves.

Claim 7

Apparatus according to claim 4 wherein said first section is a race generally tangent to said first groove and extending radially outward therefrom relative to said nut axis, in a plane transverse to said nut axis.

Claim 8

Apparatus according to claim 4 wherein said nut comprises top and bottom ends, the apparatus further comprising an annular plate securable to each of said ends, and said transfer channels each comprise two adjacent grooves, one of which is in one end plate and the other of which is in one end of said nut.

Claim 9

A re-circulating ball, screw and nut apparatus comprising cooperating screw and nut members having adjacent mating surfaces, wherein rotary motion of one of said members relative to the other causes axial motion of the other member, each of said members having defined in its mating surface axially spaced-apart first and second helical grooves of the same pitch, one of said grooves axially shifted relative to the other, and each groove has top and bottom ends, said first groove of the nut being adjacent the first groove of the screw member and forming a drive channel of first diameter, and said second groove of the nut being adjacent the second groove of the screw and forming a recirculation channel having second diameter at least equal to said first diameter, said nut member further comprising first means providing a channel having diameter at least equal to said first diameter between and connecting the top ends of the first and second grooves in said nut, and a second means providing a transfer channel having diameter at least equal to said first diameter between and connecting the bottom ends of said first and second grooves in the nut, said drive, re-circulation, and Transfer channels forming a continuous passage, the apparatus further comprising a plurality of balls of diameter slightly smaller than said first diameter and situated in said passage, whereby during rotation of one of said members relative to the other there is transmission of force between said members and said balls are movable in the drive channel to and through one transfer channel to said re-circulation channel, and to the other transfer channel.

Claim 10

A re-circulating ball, screw and nut apparatus comprising cooperating screw and nut members having adjacent mating surfaces, wherein rotary motion of one of said members relative to the other causes axial motion of the other member, each of said members having defined in its mating surface axially spaced-apart first and second helical grooves of the same pitch, one of said grooves axially shifted relative to the other, and each groove has top and bottom ends, said first groove of the nut being adjacent the first groove of the screw member and forming a drive channel of first diameter, and said second groove of the nut being adjacent the second groove of the screw and forming a recirculation channel having second diameter at least equal to said first diameter, said nut member further comprising first means providing a channel having diameter at least equal to said first diameter between and connecting the top ends of the first and second grooves in said nut, and a second means providing a transfer channel having diameter at least equal to said first diameter between and connecting the bottom ends of said first and second grooves in the nut, said drive, re-circulation, and Transfer channels forming a continuous passage, the apparatus further comprising a plurality of balls of diameter slightly smaller than said first diameter and situated in said passage, whereby during rotation of one of said members relative to the other there is transmission of force between said members and said balls are movable in the drive channel to and through one transfer channel to said re-circulation channel, and to the other transfer channel.