Half bearing and sliding bearing
Provided is a semi-cylindrical shaped half bearing. The half bearing has an inner surface forming a sliding surface and including a plurality of recesses. Each recess has a smooth recess surface and a peripheral edge. The recess surface forms a convex curve toward the outer diameter side of the half bearing in cross-sectional view in a direction parallel to a circumferential direction of the half bearing. The recess includes a groove forming zone adjacent to the peripheral edge of the recess. The groove forming zone includes a plurality of circumferential grooves. The circumferential grooves extend from the peripheral edge of the recess along the circumferential direction of the half bearing. The present invention also provides a cylindrical sliding bearing including the above half bearing.
1. A half bearing for constituting a sliding bearing for supporting a crankshaft of an internal combustion engine, the half bearing having a semi-cylindrical shape having an inner surface, the inner surface forming a sliding surface,
wherein the sliding surface of the half bearing comprises a plurality of recesses, each recess having a smooth recess surface and a peripheral edge, the recess surface recessing from the sliding surface toward an outer diameter side of the half bearing;
wherein the recess surface forms a convex curve toward the outer diameter side of the half bearing in cross-sectional view in a direction parallel to a circumferential direction of the half bearing;
wherein the recess comprises a groove forming zone adjacent to the peripheral edge of the recess, the groove forming zone comprising a plurality of circumferential grooves, the circumferential grooves recessing from the recess surface toward the outer diameter side of the half bearing; and
wherein the circumferential grooves extend from the peripheral edge of the recess along the circumferential direction of the half bearing.
2. The half bearing according to claim 1 , wherein a depth D 1 of the recess is 2 to 50 μm.
3. The half bearing according to claim 1 , wherein a depth D 2 of the circumferential grooves increases from a center of the recess toward a peripheral edge side of the recess.
4. The half bearing according to claim 1 , wherein a maximum depth (D 2 ) of the circumferential groove is 0.5 to 3 μm.
5. The half bearing according to claim 1 , wherein a maximum width W of the circumferential groove is 20 to 150 μm.
6. The half bearing according to claim 1 , wherein an area ratio S 1 of an area of the groove forming zone to an area of the recess is 0.15 to 0.55.
7. The half bearing according to claim 1 , wherein an opening of the recess has a circular shape, an elliptical shape, or a quadrilateral shape.
8. The half bearing according to claim 1 , wherein the recess surface forms a convex curve toward the outer diameter side of the half bearing in cross-sectional view in an axial direction of the half bearing.
9. The half bearing according to claim 1 , wherein the plurality of recesses are uniformly located throughout the sliding surface of the half bearing.
10. The half bearing according to claim 1 , wherein as the recess is located closer to a circumferential center CL of the half bearing, a depth D 1 of the recess increases.
11. The half bearing according to claim 1 , wherein as the recess is located closer to a circumferential center CL of the half bearing, an area A 1 of the opening of the recess increases.
12. The half bearing according to claim 1 , wherein as the recess is located closer to a circumferential center CL of the half bearing, an area ratio S 1 of an area of the groove forming zone to an area of the recess decreases.
13. A sliding bearing for supporting a crankshaft of an internal combustion engine, comprising the half bearing according to claim 1 , the sliding bearing having a cylindrical shape.
14. The sliding bearing according to claim 13 , wherein the sliding bearing comprises a combination of a pair of the half bearings.