Cylinder bore formed with oil pockets

Abstract

A cylinder bore for minimizing the friction loss may include a plurality of oil pockets formed on stroke sections that contact a piston on an interior circumference of the cylinder bore. The oil pockets may be formed by a laser honing method, and may have different shapes over the stroke sections or different shapes over the stroke sections according to stroke speeds. Moreover, the oil pockets may have a structure such that more oils can be supplied to an upper stroke section or to a lower stroke section than to a center stroke section of the cylinder bore. Furthermore, the oil pockets may be formed symmetrically with respect to a center stroke section of the cylinder bore.

1 . A cylinder bore comprising:
 a plurality of oil pockets formed on a plurality of stroke sections that contact a piston on an interior circumference of the cylinder bore, the oil pockets having their shapes over the respective stroke sections.   
     
     
         2 . The cylinder bore of  claim 1 , wherein the oil pockets have different shapes over the stroke sections according to stroke speeds. 
     
     
         3 . The cylinder bore of  claim 2 , wherein the oil pockets are shorter in length and shallower in depth in a high stroke speed section, whereas the oil pockets are longer in length and deeper in depth in a low stroke speed section. 
     
     
         4 . The cylinder bore of  claim 1 , wherein the number of stroke sections is at least three. 
     
     
         5 . The cylinder bore of  claim 4 , wherein the oil pockets have the same shapes in the at least two sections. 
     
     
         6 . The cylinder bore of  claim 5 , wherein the oil pockets have different shapes in the at least one section. 
     
     
         7 . The cylinder bore of  claim 1 , wherein the oil pockets are a structure such that more oils can be supplied to an upper stroke section or to a lower stroke section than to a center stroke section of the cylinder bore. 
     
     
         8 . The cylinder bore of  claim 1 , wherein the oil pockets are formed symmetrically with respect to a center stroke section of the cylinder bore. 
     
     
         9 . The cylinder bore of  claim 8 , wherein the oil pockets have same shapes at a top dead center stroke section and a bottom dead center stroke section, but different shapes in the center stroke section. 
     
     
         10 . The cylinder bore of  claim 9 , wherein the oil pockets are approximately 4 mm in length, 2 mm in distance between the oil pockets, 2 mm in pitch, and 15 to 20 μm in depth in the top dead center stroke section and the bottom dead center stroke section, whereas the oil pockets are approximately 1 mm in length, 2 mm in distance between the oil pockets, 2 mm in pitch, and 5 to 10 μm in depth in the center stroke section. 
     
     
         11 . The cylinder bore of  claim 1 , wherein the oil pockets are formed by a laser honing method.