Compressor Crankshaft Insert Design for Compact Accessory Drive
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Solution Overview
Problem
Commercial vehicle air compressors require a compact design to efficiently drive accessory devices while minimizing space in the engine compartment, necessitating a reduction in the overall length of the crankshaft and ensuring a stiff connection to these devices.
Innovation Solution
The crankshaft assembly features a segmented design with a cavity having varying inner diameters and an insert with matching diameters for interference fit, allowing for a compact structure that maintains torque transmission without additional fastening devices, and includes linear passages for oil routing, enabling efficient drive of accessory devices like steering pumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the crankshaft is designed with a through drive mechanism to drive accessory devices, then the accessory devices can be positioned close to the engine, but the overall length of the crankshaft increases
Solution Approach 1:
The crankshaft is divided into multiple segments (first crankshaft segment, second crankshaft segment) connected by a stiff connection structure. This segmentation allows the accessory drive mechanism to be positioned at the distal end of the second segment, enabling accessory devices to be placed close to the engine while keeping each segment compact, thus resolving the contradiction between accessory positioning and overall length.
Solution Approach 2:
The invention positions the accessory drive mechanism at the distal end of the second crankshaft segment, utilizing the axial dimension of the crankshaft. This dimensional arrangement allows accessory devices to be positioned close to the engine without proportionally increasing the overall crankshaft length, as the drive mechanism integrates with the crankshaft's existing structural dimensions.
2Length of moving object
If the crankshaft length is reduced to minimize engine compartment space, then the overall size decreases, but the torque transmission capability to accessory devices is reduced
Solution Approach 1:
The connection between the first and second crankshaft segments is designed with locally enhanced stiffness through a stiff connection structure comprising a connection portion and engagement features. This localized quality enhancement ensures adequate torque transmission capability at the joint, allowing the overall crankshaft length to be reduced without compromising the torque transmission to accessory devices.
Solution Approach 2:
The stiff connection structure incorporates different material properties and structural configurations (connection portion, engagement features, interference fit mechanisms) to achieve optimal torque transmission. This composite approach allows compact dimensions while maintaining the necessary mechanical strength and torque capacity for driving accessory devices effectively.
3Force
If a stiff connection is implemented between crankshaft segments to maintain torque, then the connection complexity increases, but the torque transmission is improved
Solution Approach 1:
The stiff connection structure merges multiple functions into a single integrated component: the connection portion provides structural coupling, the engagement features (such as interference fit mechanisms or keyways) provide torque transmission, and the geometry provides alignment. This merging reduces the number of separate parts and assembly steps, achieving adequate torque transmission without excessive connection complexity.
4Length of moving object
If the crankshaft design is optimized for compactness, then the engine compartment space is reduced, but the lubrication system complexity increases
Solution Approach 1:
The linear passage in the second crankshaft segment serves multiple functions: it provides structural integrity as part of the compact crankshaft design, routes pressurized oil to the main bearings, and maintains adequate lubrication despite the reduced overall length. This multi-functionality allows compactness optimization without proportionally increasing lubrication system complexity.
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
This design achieves a 25% reduction in crankshaft length, a 20% increase in torque, and over 30% reduction in weight and material costs, while ensuring effective lubrication and stress mitigation.
Implementation Method 1
an insert having a first end with a first insert diameter and a second end with a second insert diameter, wherein the insert is sized to be matingly engaged in the cavity
Implementation Method 2
An oil passage in the crankshaft routes pressurized oil to the main bearings of the compressor
Implementation Method 3
the crankshaft rotates continuously
Data Source
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AI summary
Various embodiments of a crankshaft assembly with an insert are disclosed. The crankshaft assembly for an air compressor comprises a crankshaft with a first segment; a second segment having an outside diameter and a cavity extending into a distal end. The cavity comprises a first portion having a first inner diameter; and a second portion having a second inner diameter, wherein the second inner diameter is less than the first inner diameter. The crankshaft includes a linear passage in the second segment, wherein the linear passage does not intersect the cavity. The crankshaft assembly includes an insert having a first end with a first insert diameter and a second end having a second insert diameter, wherein the insert is sized to be matingly engaged in the cavity.