Bevel Gear Pump Asymmetric Clearance Leakage Control
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Solution Overview
Problem
Gear pumps in automotive automatic transmissions experience fluid leaks due to thin clearances between components, leading to reduced pumping power and poor fluid balance, which can result in inadequate operation of transmission engaging elements, and existing solutions either increase gear weight or pump size, compromising compactness and efficiency.
Innovation Solution
The design incorporates annular inner and outer gears with bevel teeth that bias the inner gear to reduce the thickness of the passage part, creating a volume-changing pump chamber with controlled clearances to minimize fluid leaks, utilizing a gear receiving recess and a pump cover to house the gears and reduce the clearance between the inner gear and pump cover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the face width of each tooth of each gear is increased to minimize the clearance thickness, then the fluid leak is reduced, but the weight of each gear increases and the torque needed for driving the pump increases
Solution Approach 1:
The invention applies different face widths to different gears (inner gear has face width b1, outer gear has face width b2 where b1 < b2) and creates an asymmetric clearance distribution (clearance c1 on one side, c2 on the other side) to locally optimize fluid leakage control without uniformly increasing gear dimensions and weight
Solution Approach 2:
The invention changes the clearance parameter from a uniform thin clearance to a controlled asymmetric clearance distribution, where the clearance thickness is intentionally designed to be non-uniform to balance leakage reduction with acceptable driving torque requirements
2Loss of substance
If the face width of each tooth of each gear is increased to minimize the clearance thickness, then the fluid leak is reduced, but the size of the pump increases
Solution Approach 1:
The invention creates local quality variations in the clearance distribution around the gear periphery, with different clearance thicknesses at different angular positions, allowing leakage control without uniformly increasing the overall pump volume
3Ease of manufacture
If the clearance between the pump cover and the inner gear is increased, then the manufacturing is easier, but the fluid leak increases significantly
Solution Approach 1:
The invention changes the clearance parameter from a single uniform value to a controlled distribution of different clearance values (c1 and c2) at different locations, allowing the clearance to be larger overall for easier manufacturing while maintaining leakage control through strategic placement of thinner clearance zones
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 configuration effectively reduces fluid leaks by decreasing the clearance between the inner gear and pump cover, enhancing the pumping power and fluid balance, while maintaining compactness and reducing the need for increased gear weight or size, thus improving the operation of transmission engaging elements.
Implementation Method 1
the inner gear is driven by the driving shaft while turning the outer gear therearound, and thus the pump chamber is subjected to a volume change thereby pumping the oil through inlet and outlet ports
Implementation Method 2
annular inner and outer gears with bevel teeth that bias the inner gear to reduce the thickness of the passage part, creating a volume-changing pump chamber with controlled clearances to minimize fluid leaks
Data Source
AI summary
A gear pump has a pump housing formed with a gear receiving recess, a pump cover coupled with the pump housing to cover the gear receiving recess, a hydraulic passage that uses the gear receiving recess as a passage part thereof, and annular inner and outer gears operatively installed in the gear receiving recess. The inner and outer gears are of a bevel type and meshed with each other in such a manner as to bias the inner gear in a direction to reduce the thickness of the passage part when the inner gear is rotated while turning the outer gear therearound.