Oil control ring

An oil control ring, comprising:

• an oil ring having a pair of land parts arranged in a sliding direction and connected to each other by a web part;
• and
• a coil expander arranged on an inner circumferential side of the oil ring in a radial direction, the coil expander biasing the oil ring toward an outer circumferential side in the radial direction,
• wherein the web part of the oil ring is provided with a plurality of window holes along a circumferential direction, the window holes each extending through the web part in the radial direction;
• wherein, in an axial cross-sectional view of a largest opening portion in an axial direction of the window hole in the oil ring, an inner surface of a combustion chamber-side land part which is located on the outer circumferential side in the radial direction of the combustion chamber-side land part and connects an outer circumferential surface in the radial direction of the web part and a sliding surface of the land part, and an inner surface of a crank case-side land part which is located on the outer circumferential side in the radial direction of the crank case-side land part and connects the outer circumferential surface in the radial direction of the web part and a sliding surface of the land part, are formed so as to increase a diameter toward the outer circumferential side in the radial direction, and
• wherein, in the axial cross-sectional view of the largest opening portion of the window hole in the axial direction of the oil ring, a width H1 in the sliding direction of the oil ring and a length L1 of a combustion chamber-side non-window hole part, which excludes the window hole, in the outer circumferential surface of the web part, satisfy the following condition:
• 0.15>L1/H1≥0, wherein, in the axial cross-sectional view of the largest opening portion of the window hole in the axial direction of the oil ring, when a crank case-side end of the sliding surface of the combustion chamber-side land part is referred to as point A, a window hole-side end of the combustion chamber-side non-window hole part in the outer circumferential surface of the web part is referred to as point B, and an end of the combustion chamber-side non-window hole part, which is located on a side of the inner surface of the land part, in the outer circumference surface of the web part is referred to as point C, a distance AB between the points A and B, a distance AC between the points A and C, and a distance BC between the points B and C, satisfy the following condition:
• 1.0< (distance AC+distance BC)/(distance AB)≤1.5,
• wherein, in the axial cross-sectional view of the largest opening portion of the window hole in the axial direction of the oil ring, an area of a triangle formed by the points A, B and Cis 11% or less and greater than 0% of an area of a space formed by the pair of land parts and the web part on the outer circumferential side in the radial direction of the oil ring, and
• wherein, in the axial cross-sectional view of the largest opening portion of the window hole in the axial direction of the oil ring, an angle formed by a virtual line passing a crank case-side end of the sliding surface of the combustion chamber-side land part and the window hole-side end of the combustion chamber-side non-window hole part in the outer circumferential surface of the web part, with respect to the radial direction of the oil ring, is 33 degrees or less.