Dust stop device for sealed kneader

1. A dust stop device for a sealed kneader, the dust stop device being provided in a sealed kneader having a pair of rotors and a supporting member, the pair of rotors being disposed adjacent to each other with a predetermined gap therebetween so as to have respective axes parallel to each other and being capable of rotating in opposite directions to each other, the supporting member including a housing that houses the pair of rotors and supporting axial end portions of the pair of rotors rotatably, the dust stop device being interposed between each rotor and the supporting member to prevent a matter kneaded by the pair of rotors from leaking to an outside of the supporting member, the dust stop device comprising:

a rotating ring attached to the rotor so as to rotate with the rotor; and

a stationary ring attached to the supporting member, wherein:

the stationary ring and the rotating ring have respective contact surfaces which make surface contact with each other while being opposed to each other;

the stationary ring has a lubricating-oil supply portion which supplies lubricating oil to the respective contact surfaces of the stationary ring and the rotating ring;

the lubricating-oil supply portion has a through-hole which provides communication between the contact surface of the stationary ring and a surface opposite to the contact surface; and

at least a part of the through-hole, the part including an opening in the contact surface, is a long hole which extends along a circumferential direction of rotation of the rotating ring, the long hole having a longitudinal direction that is inclined to the rotation tangent direction such that the long hole is displaced inward in a radial direction of the rotation of the rotating ring with an advance in a rotational direction of the rotating ring, the rotation tangent direction being a direction of a tangent to the rotational direction of the rotating ring at an intermediate position of the long hole with respect to the longitudinal direction of the long hole;

wherein the long hole has a downstream end and an upstream end respectively distanced from an inner circumference and an outer circumference of the stationary ring;

the stationary ring has a plurality of said lubricating-oil supply portions;

the long holes of the plurality of the lubricating-oil supply portions are spaced circumferentially at an interval; and

the long holes of the plurality of the lubricating-oil supply portions are not overlapped to each other in the radial direction of the stationary ring.

2. The dust stop device for a sealed kneader according to claim 1 , wherein the position at which the lubricating oil is supplied to the lubricating-oil supply portion is a position upstream of the intermediate position in the length direction of the long hole, in the rotation direction of the rotating ring.

3. The dust stop device for a sealed kneader according to claim 1 , wherein the long hole of the lubricating-oil supply portion has a shape selected from a straight-shape, an arc-shape, a boomerang-shape, and an L-shape.

4. A sealed kneader comprising:

the dust stop device according to claim 1 ;

a pair of rotors disposed adjacent to each other with a predetermined gap therebetween so as to have respective axes parallel to each other and being capable of rotating in opposite directions to each other;

the supporting member including a housing that houses the pair of rotors and supporting axially opposite end portions of the pair of rotors rotatably; and

the dust stop device being interposed between each rotor and the supporting member to prevent a matter kneaded by the pair of rotors from leaking to an outside of the supporting member.