Nok Corporation

Freudenberg-nok General Partnership

Takeo Otani

Junichi Nakayama

Kokichi Hamamoto

Yosuke Kondo

Tamio Inamura

Yasuaki Tanabe

Koichi Mizunoya

A resin lip type seal () capable of increasing safety against rupture by reducing rigidity of a plate-like lip () bent around a tip point A of a approximately wedge-shaped recessed part () to reduce stress concentration at the point A, suppressing the lowering of sealability due to a reduction in creep of the lip, and increasing the follow-up capability of the lip to the eccentricity of its axis. Indentations are formed on the slidable contact surface () of the plate-like lip () or/and the anti-slidable contact surface () thereof. Indentations () are also formed on the sloped slidable contact surface () of the inner lip () of the seal. Then, the ratio of the portion of each of the slidable contact surfaces where the indentations () are formed is &#xbd; or more of each of the surface areas of the slidable contact surfaces ().

Lip type seal

The oil seal of the present invention for a valve stem includes a triple seal lip having a cam chamber side lip, a first combustion chamber side lip and a second combustion chamber side lip. Notches are provided on the second combustion chamber side lip and other notches are provided on the first combustion chamber side lip. These notches permit flow communication from the cam chamber side with the combustion chamber side. The notches provided on the combustion chamber side lip and the notches provided on the second combustion chamber side lip are placed circumferentially shifted from each other so that the notches are not axially aligned relative to the notches. Preferably, the non-notched portion is axially aligned and spaced apart relative to the notched portion. Similarly, the notched portion is axially spaced relative to the non-notched portion, such that when the valve stem moves eccentrically toward the notch on the combustion chamber side lip, the second combustion chamber side lip prevents the eccentric motion of the valve stem. When the valve stem moves eccentrically toward the notch on the second combustion chamber side lip, the combustion chamber side lip prevents the eccentric motion of the valve stem. Therefore, when compared to a conventional oil seal for the valve stem, the eccentric movement of the valve stem can be considerably reduced and the variance in the amount of oil leaking or migrating due to the eccentric movement of the valve stem, from the cam chamber side to the combustion chamber side, can be considerably reduced. Furthermore, the eccentric movement of the valve stem is reduced compared to a conventional stem, so that the wear of the oil seal of the present invention can be considerably reduced to attain stable oil migration during operation.

Oil seal

Growing community of inventors

Fukushima, Japan

Takeo Otani