Wiper ring for reciprocating compressor rod packing
View Patent ↗A rod packing assembly that includes a wiper ring is disclosed. In one embodiment, a rod packing assembly comprises a first ring, a second ring, a third ring, a first biasing member, a second biasing member, and a third biasing member. The third ring has at least one port, and is positioned between the first ring and the second ring. The first ring, the second ring, and the third ring surround a rod and to scrape a surface of the rod. The first biasing member applies a first force to urge the first ring against the rod, and the second biasing member applies a second force to urge the second ring against the rod. The third biasing member applies at least a third force to urge the third ring against the rod. The first and second rings are arranged to apply forces to urge the third ring against the rod.
1 . A rod packing assembly comprising:
a first ring;
a second ring;
a third ring including at least one port defined therein, wherein the third ring is coupled to the first ring and to the second ring, the third ring being positioned between the first ring and the second ring, and wherein the first ring, the second ring, and the third ring are configured to surround a rod and to collectively scrape a surface of the rod;
a first biasing member, the first biasing member being arranged around the first ring, wherein the first biasing member applies a first force to the first ring to urge the first ring against the rod and against the third ring, thereby urging the third ring against the rod;
a second biasing member, the second biasing member being arranged around the second ring, wherein the second biasing member applies a second force to the second ring to urge the second ring against the rod and against the third ring, thereby urging the third ring against the rod; and
at least one third biasing member, the at least one third biasing member being arranged around the third ring wherein an outer diameter of the first biasing member or an outer diameter of the second biasing member overlaps the outer diameter of the at least one third biasing member, wherein the at least one third biasing member applies at least a third force to the third ring to urge the third ring against the rod.
2 . The rod packing assembly of claim 1 wherein the surface of the rod is coated with a substance, wherein the first ring, the second ring, and the third ring are configured to collectively scrape the surface of the rod to remove the substance.
3 . The rod packing assembly of claim 2 wherein the third ring is configured to capture the substance after the substance is removed from the surface of the rod and to direct the substance through at least one port.
4 . The rod packing assembly of claim 2 wherein the first ring includes a first scraping surface, the second ring includes a second scraping surface, and the third ring includes a third scraping surface and a fourth scraping surface, the first scraping surface and the third scraping surface being configured to scrape the surface of the rod to remove the substance when the rod moves in a first direction, the second scraping surface and the fourth scraping surface being configured to scrape the surface of the rod to remove the substance when the rod moves in a second direction.
5 . The rod packing assembly of claim 1 wherein the first ring includes a first feature and the second ring includes a second feature, the first feature being arranged enable the third ring to be seated against the first ring and to allow the first ring to apply the first force to the third ring, the second feature being arranged to enable the third ring to be seated against the second ring and to allow the second ring to apply the second force to the third ring.
6 . The rod packing assembly of claim 1 further including:
a packing case, the packing case having a first surface, wherein the first ring, the second ring, and the third ring are contained within the packing case, the first ring being arranged to cooperate with the first surface to form a seal.
7 . A reciprocating compressor comprising:
a piston assembly including a piston and a piston rod;
a crankcase, the crankcase containing a crankshaft and oil, wherein the piston rod is coupled to the piston and to the crankshaft, wherein the oil coats the piston rod; and
a wiper ring positioned around the piston rod such that the piston rod moves along a first axis through the wiper ring, the wiper ring being arranged to scrape a surface of the piston rod to remove the oil from the piston rod as the piston rod moves along the first axis, the wiper ring including:
a first outer ring,
a second outer ring,
an inner ring sandwiched between the first outer ring and the second outer ring, the inner ring having a plurality of ports defined therein, and
a plurality of biasing elements, the plurality of biasing elements including a first biasing member arranged to apply a first inward force to urge the first outer ring against the piston rod, a second biasing member arranged to apply a second inward force to urge the second outer ring against the piston rod, and at least one third biasing member arranged to apply a third inward force to urge the inner ring against the piston rod, wherein an outer diameter of the first biasing member or an outer diameter of the second biasing member overlaps the outer diameter of the at least one third biasing member, wherein the first inward force and the second inward force also urge the inner ring against the piston rod, and wherein the oil removed from the piston rod is provided to the inner ring and directed through the plurality of ports.
8 . The reciprocating compressor of claim 7 wherein the first outer ring includes a first scraping surface, the second outer ring includes a second scraping surface, and the inner ring includes a third scraping surface and a fourth scraping surface, wherein the first scraping surface and the third scraping surface scrape the surface of the piston rod when the piston rod moves in a first direction along the first axis, and wherein the second scraping surface and the fourth scraping surface scrape the surface of the piston rod when the piston rod moves in a second direction along the first axis.
9 . The reciprocating compressor of claim 8 wherein the first scraping surface is a first primary scraping surface, the second scraping surface is a second primary scraping surface, the third scraping surface is a first auxiliary scraping surface, and the fourth scraping surface is a second auxiliary scraping surface, and wherein the first auxiliary scraping surface removes the oil that bypasses the first primary scraping surface and the second auxiliary scraping surface removes the oil that bypasses the second primary scraping surface.
10 . The reciprocating compressor of claim 7 further including:
a conduit, the conduit configured to return the oil removed from the piston rod and directed through the plurality of ports to the crankcase.
11 . The reciprocating compressor of claim 7 wherein the first outer ring includes a first feature and the second outer ring includes a second feature, the first feature being arranged enable the inner ring to be seated against the first outer ring and to apply the first inward force to the inner ring, the second feature being arranged to enable the inner ring to be seated against the second outer ring and to apply the second inward force to the inner ring.
12 . The reciprocating compressor of claim 7 wherein the wiper ring further includes:
a packing case, the packing case having a first surface, wherein the first outer ring, the second outer ring, and the inner ring are contained within the packing case, the first outer ring being arranged to cooperate with the first surface to form a seal.
13 . The reciprocating compressor of claim 7 wherein the plurality of biasing elements includes a plurality of springs.
14 . The reciprocating compressor of claim 7 wherein the first outer ring and the second outer ring are formed from polytetrafluoroethylene (PFTE), and wherein the inner ring is formed from polyetheretherketone (PEEK).
15 . A reciprocating compressor comprising:
a piston assembly including a piston and a piston rod;
a crankcase, the crankcase containing a crankshaft and oil, wherein the piston rod is coupled to the piston and to the crankshaft, wherein the oil coats the piston rod; and
a packing ring assembly positioned around the piston rod such that the piston rod moves along a first axis through the packing ring assembly, the packing ring assembly having a plurality of scraping surfaces arranged to be forced against a surface of the piston rod by an inward radial force imposed by a plurality of biasing members that are arranged around outer diameters of packing rings in the packing ring assembly and arranged so that at least two of the plurality of biasing members at least partially overlap, wherein the inward radial force urges the plurality of scraping surfaces to scrape the surface of the piston rod to remove the oil from the piston rod as the piston rod moves along the first axis, the packing ring assembly further being arranged to capture the oil removed from the piston rod and to direct the oil removed from the piston rod through the packing ring assembly to return the oil removed from the piston rod to the crankcase.
16 . The reciprocating compressor of claim 15 wherein the packing rings of the packing ring assembly include a first outer ring, a second outer ring, and an inner ring having a plurality of ports defined therein to direct the oil removed from the piston rod to the crankcase, the inner ring being sandwiched between the first outer ring and the second outer ring, and wherein the first outer ring and the second outer ring apply at least a part of the inward radial force to urge the inner ring against the piston rod.
17 . The reciprocating compressor of claim 16 wherein the plurality of scraping surfaces includes a first scraping surface, a second scraping surface, a third scraping surface, and a fourth scraping surface, wherein the first outer ring includes the first scraping surface arranged to scrape the surface of the piston rod to remove the oil, the second outer ring includes the second scraping surface arranged to scrape the surface of the piston rod to remove the oil, and the inner ring includes the third scraping surface and the fourth scraping surface arranged to scrape the surface of the piston rod to remove the oil.
18 . The reciprocating compressor of claim 17 wherein the first scraping surface is a first primary scraping surface, the second scraping surface is a second primary scraping surface, the third scraping surface is a first auxiliary scraping surface, and the fourth scraping surface is a second auxiliary scraping surface, and wherein the first auxiliary scraping surface removes the oil that bypasses the first primary scraping surface when the piston rod moves in a first direction along the first axis and the second auxiliary scraping surface removes the oil that bypasses the second primary scraping surface when the piston rod moves in a second direction along the first axis.
19 . The reciprocating compressor of claim 16 wherein the plurality of biasing members in the packing ring assembly include a first annular spring, a second annular spring, a third annular spring, and a fourth annular spring, the first annular spring being arranged around the first outer ring to generate a part of the inward radial force that urges the first outer ring against the piston rod, the second annular spring being arranged around the second outer ring to generate a part of the inward radial force that urges the second outer ring against the piston rod, the third annular spring being arranged around the inner ring to generate a part of the inward radial force that urges the inner ring against the piston rod, and the fourth annular spring being arranged around the inner ring to generate a part of the inward radial force that urges the inner ring against the piston rod.
20 . The reciprocating compressor of claim 19 wherein the first outer ring includes a first channel in which the first annular spring is disposed, the second outer ring includes a second channel in which the second annular spring is disposed, and the inner ring includes a third channel in which the third annular spring is disposed and a fourth channel in which the fourth annular spring is disposed.