Nok Corporation

Hideyuki Furuyama

Satoshi Yamanaka

Hiroki Matsui

Masayuki Tanida

Akira Yamaguchi

Takehiro Nakagawa

Go Kanzaki

Hideharu Hyakutake

Tsunehisa Onuma

Shinya Takeda

Yuki Sato

Kei Sasaki

Hirotaka Mizuta

Toshiki Watanabe

Kaoru Anzue

Kouichi Mizunoya

Ken Yoshikawa

Yoshihisa Yamaguchi

Masaru Shonai

To improve durability of a seal lip () of an oil seal () in slidably contact with the peripheral surface of a shaft (), a lubricating oil supply section () for collecting adhered oil and dropping it on the shaft () is provided at a forward end portion of an installation section (), the lubricating oil supply section () has projections () formed on the inner peripheral surface of the installation section () to collect oil on the surface thereof, the surface of each projection () has a recess () for temporarily accumulating oil, guidance projections, or a slope for collecting the oil, and dams are formed on a forward end face () of the installation section () to block the oil flowing down along the circumferential direction on the forward end face () and guides the oil toward each projection ().

Oil seal

For an oil seal () having a seal lip () with a slope () at the side of sealed fluid and a slope () at the side opposite to the sealed fluid, and a screw section () provided on the slope () for pushing back sealed fluid by a pumping effect at a time of rotation, in order to achieve low torque characteristics based on fluid lubrication by increasing the thickness of an oil film on sliding surfaces, an intermediate surface () is provided between the slopes (), and an oppositely threaded screw section () for sucking the sealed fluid by a pumping effect is provided on the intermediate surface () without reaching the boundary () between the intermediate surface () and the slope (), so that a threadless region is provided in the entire circumference between the screw section () and the boundary ().

A seal lip of an oil seal is in slidable contact with a peripheral surface of a shaft. A lubricating oil supply section for collecting adhered oil and dropping it on the shaft is provided at a forward end portion of an installation section. The lubricating oil supply section has projections formed on the inner peripheral surface of the installation section to collect oil on the surface thereof. The surface of each projection has a recess for temporarily accumulating oil. Guidance projections, or a slope for collecting the oil, and dams are formed on a forward end face of the installation section to block the oil flowing down along the circumferential direction on the forward end face and guides the oil toward each projection.

A sliding portion between a seal lip () and the circumference of a shaft () is made of a sliding face () so that the facial pressure at the initial action time can be lowered to suppress the proceeding of the wear of the seal lip () thereby to elongate the lifetime of a sealing device (). Moreover, screw ridges () are formed from an atmospheric side slope () to a sliding face () so that satisfactory sealing properties can be exhibited initially and endurably for a long time.

Sealing device

A sealing device comprising an annular support structure, a first annular sealing lip made of rubber and supported by the annular support structure, and a second annular sealing lip adjacent to the first annular sealing lip, the second annular sealing lip being made of resin and supported by the annular support structure. The first sealing lip made of rubber is located on the side to be scaled of the second sealing lip made of resin, and grease is held in a space formed by the first and second sealing lips and a shaft.

A sealing device including an annular support structure, a first annular sealing lip made of rubber and supported by the annular support structure, and a second annular sealing lip adjacent to the first annular sealing lip, the second annular sealing lip being made of resin and supported by the annular support structure. The first sealing lip made of rubber is located on the side to be sealed of the second sealing lip made of resin, and grease is held in a space formed by the first and second sealing lips and a shaft.

Lip-type oil seals (10) having helical pumping ribs (40) are manufactured by preparing a molded foreproduct of the seal and by trimming a hat portion (62) to form a sharp sealing edge (32). Each of the pumping ribs (40) is configured to include a first section (50) of a uniform cross-section and a bilge-shaped second section (52). Trimming is made along a trim line (68) that intersects in between the length of the first sections (50) to ensure that a length of the first sections (52) is preserved between the sealing edge (32) and the second sections (52) regardless of the tolerance of positioning of a trimming knife. Oil seals having an improved initial static and dynamic sealing performance is obtained. The second sections (52) achieves a satisfactory pumping action even after a substantial wear has taken place.

Oil seals and method of making thereof

Lip-type oil seals (10) having helical pumping ribs (40) are manufactured by preparing a molded foreproduct of the seal and by trimming a hat portion (62) to form a sharp sealing edge (32). Each of the pumping ribs (40) is configured to include a first section (50) of a uniform cross-section and a bilge-shaped second section (52). Trimming is made along a trim line (68) that intersects in between the length of the first sections (50) to ensure that a length of the first sections (50) is preserved between the sealing edge (32) and the second sections (52) regardless of the tolerance of positioning of a trimming knife. Oil seals having an improved initial static and dynamic sealing performance is obtained. The second sections (52) achieves a satisfactory pumping action even after a substantial wear has taken place.

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Fukushima, Japan

Hideyuki Furuyama