Oil seal

摘要

An oil seal has a lip seal member, a slinger and a dust cover. The slinger has a thread groove carrying out a pumping action toward a diametrically outer side. The dust cover achieves a dust shake-off action by a centrifugal force at the shaft rotating time, and a labyrinth seal action by forming a micro gap in relation to the lip seal member. The lip seal member has a main lip and a dust lip. The elastic dust lip has a first bellows portion receiving an atmospheric pressure by an inner surface and receiving an internal pressure between the lips by an outer surface, a second bellows portion receiving the atmospheric pressure by an outer surface and receiving the internal pressure between the lips by an inner surface, and a lip end. A pressure receiving area of the first bellows portion is greater than the second bellows portion.

主权项

1. An oil seal for a rotary shaft that is inserted into a shaft hole of a housing having an external side and a machine inner side, the oil seal comprising:
a lip seal member that is fixed to an inner periphery of the shaft hole of the housing; a slinger which is fixed to the rotary shaft, the slinger being integrally provided with a tubular portion that is fitted to the rotary shaft and a flange portion that extends toward an outer side in a diametrical direction from the tubular portion, the slinger inhibiting dust on the external side from entering into the machine inner side, and the slinger inhibiting a sealed fluid in the machine inner side from leaking to the external side, and the slinger being provided with a threaded groove that is configured to generate a pumping action toward the outer side in the diametrical direction on an end surface of an external side of the flange portion; and a dust cover integrally provided with a cylinder portion that is attached to the tubular portion of the slinger, and provided with a diametrical portion that extends toward the outer side in the diametrical direction from the cylinder portion, the diametrical portion having an angled portion wherein, during rotation of the shaft, the angled portion of the diametrical portion of the dust cover is configured to achieve a dust shake-off action that is generated by a centrifugal force that is generated during rotation of the shaft; the diametrical portion is spaced apart from the lip seal member by a micro gap such that, during rotation of the shaft, a labyrinth seal is generated, the lip seal member is provided with a main lip that slidably contacts the end surface on the external side of the flange portion of the slinger to seal the sealed fluid, and a dust lip that slidably contacts an outer peripheral surface of the tubular portion of the slinger to suppress intrusion of the dust, the dust lip being arranged between the main lip and the dust cover, and the dust lip is formed of an elastic body that is a concave lip facing the external side and integrally provided with a first bellows portion that receives an internal pressure between the dust lip and the main lip on an outer peripheral surface thereof, and receives an atmospheric air pressure from the external side on an inner peripheral surface thereof, a second bellows portion that receives the internal pressure between the dust lip and the main lip on an inner peripheral surface thereof and receives the atmospheric air pressure from the external side on an outer peripheral surface thereof, and a lip end that slidably contacts the outer peripheral surface of the tubular portion of the slinger, and a pressure receiving area that is greater on the first bellows portion than on the second bellows portion, the first bellows portion being a first conical portion that is axially longer than the second bellows portion that is a second conical portion.