US3871665A — Rod wiper assembly

Claim 1

Independent Claim 303 words

A piston rod wiper assembly arranged for circumferential contact of a wiper element of said assembly with a reciprocating piston rod comprising: a housing having a first central axis opening through which the piston rod is adapted to reciprocate, said housing being further provided with a concentric cavity at its outer end of greater diameter than that of said first central opening, thus forming an inner rear wall for said cavity; an annular wiper element formed of rigid, durable plastic material, fixedly arranged in said cavity; said wiper element having a body portion and an integral lip portion of reduced diameter extending axially from the body portion and having an internal circumferential face continuous with that of said body portion and an outer circumferential face intersecting the forward wall of said body portion; an annular retaining collar attached to the housing with the inner face of the collar contacting the forward wall of the body portion of said element to press the rear wall of the body portion into abutment with the rear wall of said cavity thereby forming a static seal; said retaining collar further having a flange extending radially inward toward said lip portion, thereby forming a channel between said flange and said wiper element; spring means in said channel surrounding the outer circumferential face of at least part of said lip portion adjacent its intersection with said body portion, the central opening in the annular wiper element being frusto-conical with the major diameter of the frustum being greater than that of the rod passing tHerethrough and its minor diameter slightly less than that of the rod, so that only the tip of the lip of the wiper element is in contact with the rod while the remaining inner surface of the wiper element slopes progressively away from said rod surface.

Claim 2

Dependent Claim 303 words

A piston rod wiper assembly arranged for circumferential contact of a wiper element of said assembly with a reciprocating piston rod comprising: a housing having a first central axis opening through which the piston rod is adapted to reciprocate, said housing being further provided with a concentric cavity at its outer end of greater diameter than that of said first central opening, thus forming an inner rear wall for said cavity; an annular wiper element formed of rigid, durable plastic material, fixedly arranged in said cavity; said wiper element having a body portion and an integral lip portion of reduced diameter extending axially from the body portion and having an internal circumferential face continuous with that of said body portion and an outer circumferential face intersecting the forward wall of said body portion; an annular retaining collar attached to the housing with the inner face of the collar contacting the forward wall of the body portion of said element to press the rear wall of the body portion into abutment with the rear wall of said cavity thereby forming a static seal; said retaining collar further having a flange extending radially inward toward said lip portion, thereby forming a channel between said flange and said wiper element; spring means in said channel surrounding the outer circumferential face of at least part of said lip portion adjacent its intersection with said body portion, the central opening in the annular wiper element being frusto-conical with the major diameter of the frustum being greater than that of the rod passing tHerethrough and its minor diameter slightly less than that of the rod, so that only the tip of the lip of the wiper element is in contact with the rod while the remaining inner surface of the wiper element slopes progressively away from said rod surface.

Claim 3

Dependent Claim 58 words

A wiper assembly as defined in claim 1 wherein the rear wall of said cavity, in a radial direction towards the central axis of opening in the housing, slopes outwardly and the abuting wall of the body portion of said wiper element is shaped to mate and coincide with the slope of the rear wall of said cavity.

Claim 4

Dependent Claim 35 words

A wiper assembly as defined in claim 1, wherein the wiper element is boot-shaped in radial cross-section, thus providing an instep portion at the intersection between the lip portion and body portion of said element.

Claim 5

Dependent Claim 31 words

A wiper assembly as defined in claim 1 wherein the angle of contact between the tip of the lip portion of the wiper element and the piston rod is approximately 10*.

Claim 6

Dependent Claim 86 words

A wiper assembly as defined in claim 1 wherein the outer circumferential face of said lip portion extends axially away from said intersection with the body portion of the wiper element to a lesser extent than that of said internal circumferential face, thus forming an outer edge face of the lip portion which slopes axially inward from the point of contact of the tip of the lip with the rod, such that said outer edge face is substantially parallel to the outer wall of said cavity.

Claim 7

Dependent Claim 64 words

A wiper assembly as defined in claim 1 wherein the outer edge face of the lip portion slopes axially inward at an angle of approximately 15* to a line perpendicular to the central axis of said rod, so as to provide a circumferential forward face on said wiper element having a sharp scraping action on the surface of the rod during its return stroke.

Claim 8

Dependent Claim 85 words

A wiper assembly as defined in claim 1 wherein the pressure exerted on the lip through the radially inward force of the spring means is of sufficient magnitude to maintain the tip of the lip in intimate contact with the surface of the rod, with the capability of permitting temporary lifting of such tip under excessive internal fluid pressure applied against the inner surface of said lip and following radial motion of the rod which can be induced by system vibration or external side loading.

Claim 9

Dependent Claim 202 words

An annular wiper element designed for mounting on a piston rod, for wiping said rod during axial reciprocating movement through said element, formed of a rigid polytetrafluoroethylene resin, said wiper element being substantially bootshaped in radial cross-section and comprising a relatively thick walled cylindrical body portion and an integral cylindrical lip portion extending axially from said body portion, the outer diameter of said lip portion being substantially smaller than the outer diameter of said body portion thus forming an instep at the intersection of said lip and body portions; said element having an outer linear face the extremities of which are defined by the major diameter of the body portion and an opposite linear face the extremities of which are defined by the major diameter of said lip portion; said outer face sloping inwardly from the major circumference of the body portion and in a direction toward said lip portion; said element having a continuous frustoconical inner wall extending from the outer linear face of the body portion to the opposite face of said lip portion, said inner wall being of progressively decreased diameter in the direction recited such that the slope of said face is at an angle of approximately 10*.

Claim 10

Dependent Claim 202 words

An annular wiper element designed for mounting on a piston rod, for wiping said rod during axial reciprocating movement through said element, formed of a rigid polytetrafluoroethylene resin, said wiper element being substantially bootshaped in radial cross-section and comprising a relatively thick walled cylindrical body portion and an integral cylindrical lip portion extending axially from said body portion, the outer diameter of said lip portion being substantially smaller than the outer diameter of said body portion thus forming an instep at the intersection of said lip and body portions; said element having an outer linear face the extremities of which are defined by the major diameter of the body portion and an opposite linear face the extremities of which are defined by the major diameter of said lip portion; said outer face sloping inwardly from the major circumference of the body portion and in a direction toward said lip portion; said element having a continuous frustoconical inner wall extending from the outer linear face of the body portion to the opposite face of said lip portion, said inner wall being of progressively decreased diameter in the direction recited such that the slope of said face is at an angle of approximately 10*.

Claim 11

Dependent Claim 28 words

A wiper element in accordance with claim 8 wherein said body portion outer face and the opposite face on the end of the lip portion are generally parallel.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1978-03-17	1978-09-16	1979-03-18	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1982-03-17	1982-09-16	1983-03-18	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1986-03-17	1986-09-16	1987-03-18	$7700.00	Window Closed / Lapsed

Rod wiper assembly

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