Integrated Gear Damper Assembly for Neutral Rattle Reduction
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Solution Overview
Problem
Reciprocating internal combustion engines and diesel engines generate torsional vibrations that are transmitted through gear trains, causing undesirable noise known as 'neutral rattle' due to cyclical variations in rotational speed, which existing torsional vibration dampers do not adequately address.
Innovation Solution
An integrated gear and torsional vibration damper assembly is designed, where a gear with a toothed portion and a hub portion supports a torsional vibration damper for limited rotational and dampened movement, utilizing springs to absorb and resist torsional impulses, thereby reducing the transmission of torque transients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a traditional torsional vibration damper is used separately from the gear, then the gear train structure remains simple, but the damper cannot effectively reduce neutral rattle noise due to inadequate isolation of torque transients
Solution Approach 1:
The patent combines the gear and torsional vibration damper into a single integrated assembly where the gear is directly coupled with the damper components (inertia element, springs, and dampers). This merging allows the damper to effectively isolate torque transients at the source while maintaining a compact structure that does not add significant complexity to the overall system.
Solution Approach 2:
The patent introduces an intermediate damping mechanism between the gear and the output shaft, consisting of springs and dampers that mediate the transmission of torque transients. This intermediary structure absorbs and dissipates vibrational energy, reducing neutral rattle noise without requiring complete redesign of the gear train.
2Ease of manufacture
If the gear is directly coupled to the output shaft, then the structure is simple, but torque transients are transmitted directly causing tooth-to-tooth impacts and noise
Solution Approach 1:
The patent incorporates springs and dampers in the integrated assembly that provide beforehand cushioning against torque transients. These elements are pre-positioned to absorb and dissipate impact forces before they can propagate through the gear train and cause tooth-to-tooth impacts and noise.
3Object-affected harmful factors
If a torsional vibration damper is added to reduce rotational speed variations, then noise is reduced, but the device complexity increases
Solution Approach 1:
The patent merges the gear and torsional vibration damper into a single integrated assembly, eliminating the need for separate mounting and control systems. This combination reduces the overall device complexity while maintaining the noise reduction benefits of the damper.
Solution Approach 2:
The integrated assembly serves multiple functions simultaneously: it transmits torque through the gear while also dampening torsional vibrations and reducing noise. This multi-functionality eliminates the need for additional separate components, thereby reducing device 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
The integrated assembly effectively reduces the transmission of torsional vibrations, minimizing tooth-to-tooth impacts and associated noise by using the inertia of the torsional vibration damper to absorb fluctuations in rotational speed, thus enhancing the quiet operation of gear trains.
Implementation Method 1
Generally speaking, such torsional vibration dampers utilize inertia to reduce the amount of the above-described rotational accelerations and decelerations transmitted by the engine output shaft
Implementation Method 2
utilizing springs to absorb and resist torsional impulses
Implementation Method 3
a torsional vibration damper supported on the gear for limited rotational and dampened movement relative to each other
Data Source
AI summary
An integrated gear and torsional vibration damper assembly (10, 20, 30, 30) includes a gear (11, 21, 31, 41) having a toothed portion (11a, 21a, 31a, 41a) and a torsional vibration damper (12, 22, 32, 42) supported on the gear (11, 21, 31, 41) for limited rotational and dampened movement relative to each other. The gear (11) may include a hub portion (11b), and the torsional vibration damper (12) may be supported on the hub portion (11b) of the gear (11). Alternatively, the gear (21) may include a hub portion (21b), an intermediate ring (23) may be supported on the hub portion (21b) of the gear (21), and the torsional vibration damper (22) may be supported on the intermediate ring (23). Alternatively, the gear (31) may include a toothed portion (31a) and a hub portion (31b) that extends radially inwardly from the toothed portion (31a) and has an opening (31c) extending therethrough, and the torsional vibration damper (32) may extend through the opening (31c). Alternatively, the gear (41) may include an inner circumferential surface that engages and supports an outer circumferential surface of the torsional vibration damper (41).