The Patent Literature 1 describes a slide bearing suitable to a rack bush which supports a load applied to a rack shaft of a steering mechanism of a vehicle while allowing linear movement of the rack shaft.
This slide bearing comprises: a bearing main body of a cylindrical shape into which a rack shaft is inserted; and an elastic ring which is mounted on the bearing main body and biases the bearing main body radially inward. The bearing main body is made of synthetic resin, and comprises: a plurality of first slits formed along the axial direction from one end surface toward the other end surface; a plurality of second slits formed along the axial direction from the other end surface toward the one end surface; and a mounting groove formed in an outer peripheral surface of the bearing main body in which the elastic ring is mounted.
Here, the first slits are positioned in one half cylinder part of the bearing main body divided by an imaginary plane which includes the axis of the bearing main body, and the second slits are positioned in the other half cylinder part of the bearing main body divided by that imaginary plane. Further, the first and second slits are formed so that the slit width in the direction parallel to the imaginary plane is constant or becomes big gradually from the inside to the outside of the half cylinder part in the direction perpendicular to the imaginary plane.
According to the slide bearing described in the Patent Literature 1, the bearing main body is contracted in diameter by the elastic ring so that the bearing main body clamps the rack shaft, and the clearance between the inner peripheral surface of the bearing main body and the outer peripheral surface of the rack shaft is reduced to zero. As a result, it is possible to prevent generation of unpleasant sound due to collision between the inner peripheral surface of the bearing main body and the outer peripheral surface of the rack shaft, and it is possible to prevent variation of friction torque caused by dimension error of the outer diameter of the rack shaft.
Further, in the slide bearing described in the Patent Literature 1, the first and second slits are formed so that the slit width in the direction parallel to the imaginary plane including the axis of the bearing main body is constant or becomes big gradually from the inside to the outside of the half cylinder part in the direction perpendicular to the imaginary plane. Therefore, the bearing main body can be molded by using an outer mold (upper mold) for the one half cylinder part of the bearing main body divided by the imaginary plane, an outer mold (lower mold) for the other half cylinder part of the bearing main body divided by the imaginary plane, and a core for forming the hollow space (the insertion hole for the rack shaft) of the bearing main body. Accordingly, it is not needed to use outer molds divided in number equal to number of the first slits and the second slits, and this reduces the production costs of the slide bearing.
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USPTO Backgrounds