Reciprocating Piston Mechanism With Through-Hole Drive Shaft Assembly
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Solution Overview
Problem
The existing reciprocating piston mechanisms in internal combustion engines are complex to assemble, particularly due to the limited operating space where the drive wheel and drive shaft need to be fixed, making it difficult to integrate the drive wheel with the crankshaft without obstructing the crankpin.
Innovation Solution
A through-hole with a larger diameter than the drive wheel allows the drive shaft and drive wheel to be fixed separately before being inserted into the crankshaft, enabling the drive shaft to be positioned independently of the crank arm, and the use of a shaft housing that can be pre-assembled with gears and pulleys facilitates easier assembly by allowing the drive shaft to protrude and be fixed at a side opposite the crankpin, simplifying the assembly process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drive wheel is pressed onto the drive shaft after crankshaft assembly, then the drive wheel and drive shaft are fixed together, but the operating space is limited and assembly becomes difficult
Solution Approach 1:
The drive wheel is preliminarily fixed to the drive shaft before the drive shaft is inserted into the crankshaft. This preliminary assembly action is performed in a space with sufficient operating room, avoiding the limited space problem during final assembly.
Solution Approach 2:
The assembly process is segmented into distinct stages: first fixing the drive wheel to the drive shaft, then inserting the assembled drive shaft into the crankshaft through the through-hole. This segmentation allows each sub-assembly to be completed in optimal conditions.
2Ease of manufacture
If the drive shaft is inserted through the crankshaft after fixing the drive wheel, then the components are integrated, but the assembly process becomes complex due to space constraints
Solution Approach 1:
The drive wheel and drive shaft are preliminarily assembled before insertion into the crankshaft. This preliminary action simplifies the overall assembly process by reducing the number of steps that must be performed in the constrained space of the crankshaft interior.
Solution Approach 2:
The drive shaft with the drive wheel is extracted as a separate sub-assembly, to be inserted through the through-hole in the crankshaft. This extraction approach allows the sub-assembly to be prepared independently with easier access to all components.
3Reliability
If the drive wheel and drive shaft are fixed at the side of the crank arm where the crankpin is located, then the components are assembled, but the limited operating space makes assembly difficult
Solution Approach 1:
The drive shaft assembly is extracted as a separate unit that will be inserted through the through-hole, allowing the drive wheel to be fixed to the drive shaft in a location with sufficient operating space rather than in the constrained area near the crankpin.
Solution Approach 2:
The assembly approach transitions from working in the limited two-dimensional space near the crankpin to utilizing the third dimension by inserting the pre-assembled drive shaft through the through-hole from the opposite side of the crankshaft.
Data Source
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AI summary
A reciprocating piston mechanism comprises a crankcase (2), a crankshaft (3) having a crankshaft axis (4), a crankpin (6), a crank arm (7) and a crankshaft portion (5) extending parallel to the crankpin (6), wherein the crank arm (7) is located between the crankshaft portion (5) and the crankpin (6) as seen along the crankshaft axis (4). The crankshaft (3) is supported by the crankcase (2) and rotatable with respect thereto about the crankshaft axis (4). The mechanism further comprises a connecting rod (11) including a big end (10) and a small end (12), a piston (13) being rotatably connected to the small end (12) and a crank member (8). The crank member (8) is rotatably mounted on the crankpin (6) and comprises a bearing portion (9) having an outer circumferential wall which bears the big end (10) of the connecting rod (11) such that the connecting rod (11) is rotatably mounted on the bearing portion (9) of the crank member (8) via the big end (10). The crank member (8) is driveably coupled to a drive wheel (24) for driving the crank member in rotational direction with respect to the crankpin (6). The drive wheel (24) is disposed at the same side of the crank arm (7) as the crank member (8) and fixed to a drive shaft (23) that is rotatably mounted to the crankshaft (3) and that extends in the same direction as the crankshaft axis (4) through a through-hole (26) in the crank arm (7). The through-hole (26) has a larger diameter than an external diameter of the drive wheel (24).