Rotor for electric water pumps and sliding bearing device for water pumps

A sliding bearing device for water pumps, the sliding bearing device being configured to be used in a water pump having an impeller, a shaft that fixes the impeller, a cylindrical sliding bearing fixed to the impeller for rotatably supporting the impeller relative to the shaft, cylindrical thrust receivers that slide on respective end surfaces of the sliding bearing, and a casing and a cover that house the impeller and form a pump chamber, the water pump being configured to suck and discharge circulation water through the pump chamber using rotation of the impeller,

• the sliding bearing device for water pumps comprising the sliding bearing and the thrust receivers,
• wherein:
• a land part serving as a sliding surface, and a lubrication groove that discharges the circulation water from an inner diameter side toward an outer diameter side are formed on a surface of at least one component of at least one end surface of the sliding bearing, and a thrust receiver of the thrust receivers,
• the lubrication groove has an inclined surface inclined relative to the land part and is configured to generate dynamic pressure due to the relative rotation between the sliding bearing and the thrust receiver,
• in a projection view of the surface on which the lubrication groove is formed, seen from a front side thereof, the lubrication groove is formed by a region surrounded by:
• a line A and a line B, where each of A and B extends on the surface from the inner diameter side to the outer diameter side;
• a circular arc C along an inner diametrical surface;
• and a circular arc D along an outer diametrical surface,
• the lubrication groove has a groove width formed by the line A and the line B,
• the line A and the line B are straight,
• an extension of the line A passes through an axial center of the component on which the lubrication groove is formed,
• the length of the circular arc C is more than the length of the circular arc D, wherein an angle between the line A and the line B is 0-15 degrees,
• wherein the lubrication groove is a plurality of lubrication grooves, and the lubrication grooves are disposed on the respective surfaces of the at least one component at any intervals in the circumferential direction,
• each of the lubrication grooves is disposed offset, from each line A, toward a downstream side in a direction of the relative rotation,
• the lubrication grooves have a groove side surface formed by the line B, a groove bottom surface connected to the groove side surface and inclined toward the land part, and the groove bottom surface has a groove depth that becomes smaller toward the line A, and
• an inclined surface, having a gradient steeper than the groove bottom surface, is formed on a boundary between an end portion of the groove bottom surface at an upstream side in a rotational direction and the land part.