Gerotor Pump Inner Rotor Fluid Passages
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Solution Overview
Problem
Gerotor oil pumps induce pressure ripples and tonal noise in powertrain components due to their positive displacement characteristic and tight clearances, leading to noise, vibration, and harshness (NVH) issues, which existing mitigation techniques like damping devices only partially address.
Innovation Solution
The design of a gerotor pump with an inner rotor featuring fluid passages that connect nonadjacent pockets, disrupting harmonics and reducing pressure ripples, while maintaining overall pumping efficiency by isolating remaining pockets from fluid passages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional gerotor pump is used, then pumping efficiency is maintained, but pressure ripples and tonal noise are generated causing NVH issues
Solution Approach 1:
The pump chamber is segmented into multiple pockets, and fluid passages are selectively provided in only some of these pockets to disrupt pressure wave harmonics. This segmentation approach breaks down the pressure ripples into lower peaks while maintaining overall pumping efficiency, as the fluid passages are strategically positioned to affect only specific harmonic frequencies.
Solution Approach 2:
Different pockets within the pump chamber are given different properties: some pockets contain fluid passages while others remain without. This local differentiation allows the pump to reduce pressure ripples in specific regions while maintaining efficient pumping in other regions, resolving the contradiction between noise reduction and pumping efficiency.
2Object-affected harmful factors
If damping devices are added to reduce noise, then tonal noise is reduced, but device complexity and cost increase
Solution Approach 1:
The noise reduction function is merged into the pump structure itself by integrating fluid passages directly into the inner rotor pockets. This eliminates the need for separate damping devices, as the pump housing and rotor design itself provides the noise mitigation through harmonic disruption, thereby reducing device complexity while maintaining noise reduction effectiveness.
Data Source
AI summary
A gerotor pump has a pump housing defining a chamber and having a fluid inlet and a fluid outlet. An outer gear member is supported for rotation within the chamber about a first axis, the outer gear member having a series of internal teeth. An inner gear member or inner rotor is rotatably supported within the outer gear member about a second axis spaced apart from the first axis. The inner gear member defining a series of external teeth interposed with a series of external pockets. The inner gear member defines a fluid passage therethrough to fluidly connect two nonadjacent pockets, with another pocket independent of fluid passages. The fluid passage is configured to disrupt harmonics during operation to reduce pressure ripples and associated tonal noise.