Piston combinations for opposed-piston engines
A combination for an opposed-piston engine includes an intake piston and an exhaust piston, each with a top land height. The intake piston top land height is less than the exhaust piston top land height.
1. An opposed-piston internal combustion engine, comprising:
an intake piston comprising:
a first crown with a first end surface;
a first set of ring grooves comprising at least one ring groove separated from the first end surface by a first top land height; and
a first piston bowl in the first piston crown; and
an exhaust piston disposed in opposition to the intake piston, the exhaust piston comprising:
a second crown with a second end surface;
a second set of ring grooves comprising at least one ring groove separated from the second end surface by a second top land height; and
a second piston bowl in the second piston crown,
in which the first top land height is less than the second top land height.
2. The opposed-piston engine of claim 1 , further comprising a cylinder in which the intake and exhaust pistons are situated in an opposing manner, such that a combustion chamber is formed between the first piston bowl and the second piston bowl when the pistons are at or near top center locations in the cylinder.
3. The opposed-piston engine of claim 2 , wherein, during operation of the engine:
the intake piston moves across intake port openings of an intake port in the cylinder to open and close the intake port; and
the exhaust piston moves across exhaust port openings of an exhaust port in the cylinder to open and close the exhaust port.
4. The opposed-piston engine of claim 1 , wherein a ratio of the first top land height to the second top land height is 1.0:2.0.
5. The opposed-piston engine of claim 1 , wherein a ratio of the first top land height to the second top land height is 1.0:1.8.
6. The opposed-piston engine of claim 1 , wherein a ratio of the first top land height to the second top land height is 1.0:1.67.
7. The opposed-piston engine of claim 1 , wherein a ratio of the first top land height to the second top land height is within a range of 1.0:1.45 to 1.0:2.0.
8. The opposed-piston engine of claim 1 , wherein:
the first piston bowl differs from the second piston bowl such that the first and second piston bowls create an asymmetrically-shaped combustion chamber when the intake and exhaust pistons are at minimum volume locations when the opposed-piston engine is in use.
9. A piston combination for an opposed-piston engine, the piston combination comprising an intake piston comprising a top land having a first height, and an exhaust piston comprising a top land having a second height, in which the first height is less than the second height.
10. The piston combination of claim 9 , wherein a ratio of the first height to the second height is 1.0:2.0.
11. The piston combination of claim 9 , wherein a ratio of the first height to the second height is 1.0:1.8.
12. The piston combination of claim 9 , wherein a ratio of the first height to the second height is 1.0:1.67.
13. The piston combination of claim 9 , wherein a ratio of the first height to the second height is within a range of 1.0:1.45 to 1.0:2.0.