US3678776A — Sealing and wiping means for ball screw actuator

Claim 1

Independent Claim 312 words

In a ball screw actuator having a screw embraced by a nut with given dimensional tolerances of the nut and screw providing a given range of clearances between the nut and the screw, wherein the screw has an outer circumferential helical groove cooperating with an inner circumferential helical groove of the nut to form a ball race, the improvement to seal off the ball race from one end of the nut and to keep lubricant in the ball race and to prevent foreign material from entering the ball race, comprising: the nut being formed with a continuous inner circumferential channel; a resiliently deformable elastomer ring seated in the channel; and cooperative means on the nut and the ring respectively interlocking the nut and the ring to prevent rotation of the ring relative to the nut, said ring having a body with an outer circumferential surface and at least two side surfaces defining the width of the ring, and having at least one continuous sealing rib disposed on the outer circumferential surface of the body and of substantially less width than the width of the body for continuous sealing contact with the bottom wall of the channel, the radial dimension of the ring including the sealing rib relative to the radial dimension of the channel being of a magnitude for the ring to form an effective seal between the nut and the screw without binding compression of the body of the ring at the minimum clearance in said range of clearances, the radial dimension of the rib being of a magnitude for the ring to form an effective seal between the nut and screw at maximum clearance within said range, whereby compensation for the range of clearances between the nut and the screw is provided primarily by resilient compression of the sealing rib as distinguished from compression of the body of the ring.

Claim 2

Dependent Claim 312 words

In a ball screw actuator having a screw embraced by a nut with given dimensional tolerances of the nut and screw providing a given range of clearances between the nut and the screw, wherein the screw has an outer circumferential helical groove cooperating with an inner circumferential helical groove of the nut to form a ball race, the improvement to seal off the ball race from one end of the nut and to keep lubricant in the ball race and to prevent foreign material from entering the ball race, comprising: the nut being formed with a continuous inner circumferential channel; a resiliently deformable elastomer ring seated in the channel; and cooperative means on the nut and the ring respectively interlocking the nut and the ring to prevent rotation of the ring relative to the nut, said ring having a body with an outer circumferential surface and at least two side surfaces defining the width of the ring, and having at least one continuous sealing rib disposed on the outer circumferential surface of the body and of substantially less width than the width of the body for continuous sealing contact with the bottom wall of the channel, the radial dimension of the ring including the sealing rib relative to the radial dimension of the channel being of a magnitude for the ring to form an effective seal between the nut and the screw without binding compression of the body of the ring at the minimum clearance in said range of clearances, the radial dimension of the rib being of a magnitude for the ring to form an effective seal between the nut and screw at maximum clearance within said range, whereby compensation for the range of clearances between the nut and the screw is provided primarily by resilient compression of the sealing rib as distinguished from compression of the body of the ring.

Claim 3

Dependent Claim 60 words

An improvement as set forth in claim 1 In which the radial dimension of the rib at a point of minimum clearance in the range of clearances is at least approximately one-half of the maximum clearance in said range of clearances to prevent excessive stressing of the body of the ring at the minimum clearance in the range of clearances.

Claim 4

Dependent Claim 48 words

An improvement as set forth in claim 1 in which the radial dimension of the sealing rib substantially exceeds one-half of the maximum clearance in said range of clearances to prevent excessive stressing of the body of the ring at the minimum clearance in the range of clearances.

Claim 5

Dependent Claim 29 words

An improvement as set forth in claim 1 in which the inner circumference of the ring embraces at least one full turn of the helical groove of the screw.

Claim 6

Dependent Claim 55 words

An improvement as set forth in claim 1 in which the channel is wider than the ring to provide the ring with freedom of axial movement within at least a portion of the channel, and in which the interlocking means permits said freedom of axial movement to accommodate backlash between the screw and the nut.

Claim 7

Dependent Claim 16 words

An improvement as set forth in claim 1 in which the ring is made of polyethylene.

Claim 8

Dependent Claim 79 words

An improvement as set forth in claim 1 in which the ring has a first continuous outer circumferential sealing rib adjacent one of the side edges of the ring and cooperating with the channel to maintain the lubricant upon the helical groove of the nut, and a second continuous outer circumferential sealing ring adjacent the other of the side edges of the ring and cooperating with the channel to seal foreign matter exterior of the nut from the lubricant.

Claim 9

Dependent Claim 46 words

An improvement as set forth in claim 1 in which the ring has a single outer circumferential sealing rib centrally disposed upon the circumference of the ring except in the region of the interlocking means, the surrounding sealing rib being continuous with the single sealing rib.

Claim 10

Dependent Claim 61 words

An improvement as set forth in claim 1 in which the cooperating interlocking means comprises a recess in one of said nut and said ring and means projecting into the recess from the other of said nut and said ring, said projecting means being of less cross section than the recess to permit the ring to shift axially in the channel.

Claim 11

Dependent Claim 25 words

An improvement as set forth in claim 9 in which the recess is in the nut and the projecting means is integral with the ring.

Claim 12

Dependent Claim 16 words

An improvement as set forth in claim 9 in which the recess is in the ring.

Claim 13

Dependent Claim 57 words

An improvement as set forth in claim 1 in which the nut has a radial bore in the region of the channel and means projects from the ring into the bore to interlock the ring with the nut, the bore being oversized relative to the projecting means to permit the ring to shift axially in the channel.

Claim 14

Dependent Claim 18 words

An improvement as set forth in claim 12 in which said projecting means is integral with the ring.

Claim 15

Dependent Claim 44 words

An improvement as set forth in claim 12 in which the ring has a radial bore registered with the radial bore of the nut, and the projecting means comprises a pin which extends through the two bores to interlock the ring with the nut.

Claim 16

Dependent Claim 68 words

An improvement as set forth in claim 1 in which one of said nut and said ring has a keyway substantially parallel with its axis and key anchored to the other of said nut and said ring slidingly engages said keyway to prevent rotation of the ring relative to the nut, the key being shorter than the keyway to permit the ring to shift axially within the channel.

Claim 17

Dependent Claim 28 words

An improvement as set forth in claim 15 in which the keyway is in the outer circumference of the ring and the key is anchored to the nut.

Claim 18

Dependent Claim 212 words

In a ball screw actuator comprising a screw having an outer circumferential helical groove embraced by a nut having a helical groove on the inner circumferential surface, a seal for wiping the helical groove of the screw and sealing a lubricant within the actuator, comprising: a resiliently deformable ring having an inner surface for wiping the helical groove of the screw and an outer circumferential surface for slidingly engaGing at least a portion of the inner circumferential surface of the nut; first means extending from the circumferential surface of the nut and disposed relative to the ring and the nut and having a configuration relative to the nut for resisting the rotation of the ring relative to the nut while permitting the axial movement of the ring relative to the nut along at least a portion of the inner circumferential surface of the nut; and second means extending from the circumferential surface of the ring and having a configuration relative to the nut to provide a seal between the ring and the nut, the second means having properties for absorbing substantially all of the overstressing of the ring relative to the nut when the clearance between the screw and the nut is reduced whereby the configuration of the ring is substantially maintained.

Claim 19

Dependent Claim 212 words

In a ball screw actuator comprising a screw having an outer circumferential helical groove embraced by a nut having a helical groove on the inner circumferential surface, a seal for wiping the helical groove of the screw and sealing a lubricant within the actuator, comprising: a resiliently deformable ring having an inner surface for wiping the helical groove of the screw and an outer circumferential surface for slidingly engaGing at least a portion of the inner circumferential surface of the nut; first means extending from the circumferential surface of the nut and disposed relative to the ring and the nut and having a configuration relative to the nut for resisting the rotation of the ring relative to the nut while permitting the axial movement of the ring relative to the nut along at least a portion of the inner circumferential surface of the nut; and second means extending from the circumferential surface of the ring and having a configuration relative to the nut to provide a seal between the ring and the nut, the second means having properties for absorbing substantially all of the overstressing of the ring relative to the nut when the clearance between the screw and the nut is reduced whereby the configuration of the ring is substantially maintained.

Claim 20

Dependent Claim 70 words

A seal as set forth in claim 17 wherein the first means includes a recess in one of said nut and said ring and means projecting into the recess from the other of said nut and said ring, said projecting means being of less axial cross section than the recess to permit the ring to shift axially on at least a portion of the inner circumferential surface of the nut.

Claim 21

Dependent Claim 23 words

A seal as recited in claim 18 wherein the recess is in the nut and the projecting means is integral with the ring.

Claim 22

Dependent Claim 15 words

A seal as defined in claim 18 in which the recess is in the ring.

Claim 23

Dependent Claim 77 words

A seal as defined in claim 17 wherein the second means comprises: at least one continuous annular lip integral with the ring for displacing the outer circumferential surface of the ring from the inner circumferential surface of the nut, wherein an outward radial force on the ring tends to flatten the lip to decrease the distance between the ring and the inner circumferential surface of the nut so that the confirmation of the ring is substantially maintained.

Claim 24

Dependent Claim 59 words

The seal as set forth in claim 17 wherein the ring has a body portion defined by: a pair of axially displaced side surfaces and the inner and outer circumferential surfaces and; wherein the continuous annular lip is disposed on the outer circumferential surface of the ring to space the ring from the inner circumferential surface of the nut.

Claim 25

Dependent Claim 71 words

The seal as recited in claim 22 wherein the annular lip has an axial width substantially less than the axial width of the ring between the pair of side surfaces so that a radial force on the ring creates a greater pressure on the annular lip than on the body portions of the ring whereby the annular lip is substantially deformed and the confirmation of the body portion is substantially maintained.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1975-07-25	1976-01-24	1976-07-25	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1979-07-25	1980-01-24	1980-07-25	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1983-07-25	1984-01-24	1984-07-25	$7700.00	Window Closed / Lapsed

Sealing and wiping means for ball screw actuator

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