Patent ID: 9169931
Filing Date: 2015-10-27
Classification: F16J

Abstract:
1. A mechanical seal for sealing a liquid comprising: a first sliding component having an annular first sliding surface; and a second sliding component configured to rotate relative to the first sliding component, the second sliding component having an annular second sliding surface that slides on the first sliding surface, wherein a liquid phase made of the liquid and a gas phase made of gas generated due to cavitation in the liquid are formed between the first and the second sliding surfaces during relative rotation of the first and the second sliding components, one of the first and the second sliding, surfaces is provided with a plurality of dimples, each dimple having a shape that is circumferentially symmetric on each side of a line that radially bisects the dimple in a plan view, and, a geometric harrier configured to block a flow of the liquid flowing towards the each dimple and form a gaseous film extending in a direction of the flow during the relative rotation of the first and the second sliding components, the geometric harrier being an upstream portion of an opening edge of the each dimple, the upstream portion being formed into a shape having an angle of 130 degrees or less between the sliding surface and a side face of the each dimple, wherein every two consecutive dimples of the plurality of dimples in the direction of the flow are arranged next to each other in the direction of the flow and within the gaseous film formed by one dimple on the upstream side, the plurality of dimples is arrayed along an entire circumference of the one of the first and the second sliding surfaces, the plurality of dimples is arrayed on each of a plurality of virtual circumferences within the entire circumference of one of the first and second sliding surfaces having center points at a rotation center of the first and second sliding components, the plurality of virtual circumferences having different diameters, whereby a plurality of dimples arrayed on a smaller one of two consecutive virtual circumferences and a plurality of dimples arrayed on a larger one of the two consecutive virtual circumferences are arrayed so as to leave a space between a virtual circle defined by outermost points of the plurality of dimples arrayed on the smaller one of the two consecutive virtual circumferences and another virtual circle defined by innermost points of the plurality of dimples arrayed on the larger one of the two consecutive virtual circumferences, and the mechanical seal satisfies parameters (1) to (3): wherein Dr is a radial width of the each dimple, W is a radial width of the one of the first and second sliding surfaces, n is the number of radially arrayed dimples in the radial width of the one of the first and second sliding surfaces, S is an interval between two dimples adjacent to each other in the circumferential direction and T is a radial width of two dimples adjacent to each other in the circumferential direction that are circumferentially aligned with each other.