Crankshaft Balancing Assembly with Offset Pivot Axis
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Solution Overview
Problem
Powertrains with crankshafts experience discontinuous rotation due to the timing of combustion and piston movement, leading to irregularities that conventional balancers may not fully mitigate, resulting in vibration and inefficiency.
Innovation Solution
A crankshaft-balancing assembly that includes a drive member secured to the crankshaft, a first shaft rotatable about a pivot axis, and a weight member extending from the shaft to balance the crankshaft during rotation, with a drive member surrounding the shaft and weight member to counteract irregularities, minimizing vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional balancer is used to minimize crankshaft rotation irregularities, then the balancing effect is limited, but the device complexity remains low
Solution Approach 1:
The balancer is divided into two independent rotating components: a drive member that rotates with the crankshaft and a shaft member that rotates independently about a pivot axis. This segmentation allows each component to perform its specific function - the drive member receives rotational input while the shaft member generates the balancing counterweight motion, thereby improving balancing effectiveness without requiring a completely complex integrated mechanism
Solution Approach 2:
The shaft member is positioned within the drive member, with the shaft rotating about a pivot axis that is offset from the drive member's rotation axis. The weight member extends from the shaft and is partially surrounded by the drive member, creating a nested configuration. This nesting allows the balancing mechanism to be compact while maintaining the independent rotation capability of each component, improving balancing effectiveness without proportionally increasing device complexity
2Object-affected harmful factors
If a weight member is added to balance the crankshaft, then vibration is reduced, but the device complexity increases
Solution Approach 1:
A weight member is attached to the shaft member and positioned to create a counterbalancing force against the crankshaft's rotational irregularities. The weight member's position along the shaft is specifically configured to generate opposing centrifugal forces that cancel out the vibration-causing forces from the crankshaft, thereby reducing vibration while using a relatively simple additive component rather than a complex active control system
Solution Approach 2:
Instead of directly balancing the crankshaft at its rotation axis, the invention uses an inverted approach by introducing a second rotation axis (the pivot axis of the shaft member) that is offset from the crankshaft axis. The weight member rotates about this inverted/offset axis, creating balancing forces through a different geometric configuration, which reduces vibration while maintaining reasonable device complexity
3Volume of moving object
If the drive member surrounds the shaft and weight member, then space is saved, but the manufacturing precision requirements increase
Solution Approach 1:
The drive member is configured to surround the shaft member and partially surround the weight member, creating a nested arrangement where components are housed within one another. This nesting achieves compact packaging by utilizing the internal space of the drive member for the shaft and weight member, rather than requiring separate external mounting space
Solution Approach 2:
The drive member features an asymmetric void configuration that specifically opposes the weight member's position. The void is shaped and positioned to accommodate the weight member's orbital path while maintaining structural integrity of the drive member. This asymmetric design allows the surrounding configuration to achieve compactness without requiring uniformly high manufacturing precision throughout the entire drive member structure
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces the irregularities and vibrations in the crankshaft's rotation, enhancing the smooth operation and efficiency of the powertrain by balancing the rotational forces.
Implementation Method 1
a weight member that extends from the first shaft. The weight member is positioned along the first shaft to balance the crankshaft during rotation of the crankshaft and the first shaft
Data Source
AI summary
A powertrain includes a housing and a crankshaft-balancing assembly that is at least partially disposed inside the housing. The crankshaft-balancing assembly includes a crankshaft rotatable about a longitudinal axis. The crankshaft-balancing assembly further includes a drive member secured to the crankshaft. The crankshaft-balancing assembly also includes a first shaft rotatable about a first pivot axis. The first shaft is rotatable in response to rotation of the crankshaft. The crankshaft-balancing assembly includes a weight member that extends from the first shaft. The weight member is positioned along the first shaft to balance the crankshaft during rotation of the crankshaft and the first shaft. The crankshaft-balancing assembly also includes a drive member that surrounds the first shaft and a portion of the weight member. The drive member of the first shaft defines a void that opposes the portion of the weight member.