Piston Oil Return Passage Structure for Low Oil Consumption
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Solution Overview
Problem
Existing piston designs with small oil return holes lead to increased engine oil consumption at low speeds and high loads, and difficulty in machining, which affects durability and emission compliance.
Innovation Solution
A piston with an oil return passage featuring a ring groove and recessed surface window, where the oil return hole is arranged on the remaining ring land and has a larger opening than the bottom, extending radially and with a depth greater than the ring groove, enhancing oil circulation and reducing accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the oil return hole cross-section is made small, then the piston structure is simpler, but the oil return ability is insufficient leading to increased engine oil consumption
Solution Approach 1:
The oil return hole is segmented into multiple sections: an upper section, a lower section, and a connecting section. The upper and lower sections have different cross-sectional areas, with the upper section having a larger area to improve oil return ability and the lower section having a smaller area to maintain structural simplicity. This segmentation allows the system to achieve both reduced oil consumption and structural simplicity.
2Loss of substance
If the oil return hole cross-section is made large, then the oil return ability is improved, but the piston structure becomes more complex and machining difficulty increases
Solution Approach 1:
The oil return hole exhibits local quality variations along its length. The upper section has a larger cross-sectional area to handle high oil return demands, while the lower section has a smaller cross-sectional area that is easier to machine. The connecting section smoothly transitions between these two sections. This local quality differentiation allows the structure to optimize oil return ability where needed while maintaining manufacturing ease in other areas.
3Loss of substance
If the oil return hole depth is increased, then the oil return ability is improved, but burr formation and machining difficulty increase
Solution Approach 1:
The oil return hole employs a dynamic cross-sectional area design that varies along its length. The upper section has a larger cross-sectional area to enhance oil return ability, while the lower section has a smaller cross-sectional area that reduces burr formation during machining. The connecting section provides a smooth transition between these sections, optimizing both oil return performance and manufacturing precision by reducing stress concentration and burr formation at the hole bottom.
Data Source
AI summary
A piston with an oil return channel may include a piston head, a piston skirt, and an oil return hole. The piston head may include a ring groove. The piston skirt may be connected to the piston head. The piston skirt may have a surface including a concave face window. A connection between the face window and the ring groove may form a residual ring bank. The oil return hole may be formed by milling on the residual ring bank. The oil return hole may connect the ring groove close to the piston skirt with the face window. A depth of the oil return hole may be greater than a depth of the ring groove.