Differential Case Weir Structure for Startup Oil Retention
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Solution Overview
Problem
The existing differential gear designs face a shortage of lubricating oil when the vehicle starts to travel, leading to inadequate lubrication and cooling of sliding portions, even with an oil outflow regulation member.
Innovation Solution
The differential gear incorporates seat surfaces on the inner peripheral surface of the differential case with weir portions that connect between adjacent surfaces, forming an oil reservoir portion on the opposite side of the opening portion, ensuring lubricating oil is secured and distributed to sliding portions, thereby increasing surface pressure and maintaining adequate lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oil outflow regulation member is disposed in the differential case to reserve oil to the radially inner side, then oil can be supplied to side washers irrespective of rotational state, but lubricating oil becomes insufficient when the vehicle starts to travel and the oil pump starts suctioning
Solution Approach 1:
The differential case inner peripheral surface is segmented into multiple functional zones: seat surfaces for supporting pinion gears, weir portions extending between adjacent seat surfaces, and oil reservoir portions formed by the weir portions. This segmentation creates dedicated oil storage areas that maintain lubricating oil supply even when the oil pump is actively suctioning oil, resolving the contradiction between reliable lubrication and sufficient oil quantity during vehicle operation.
2Volume of moving object
If the differential gear is made compact, then the overall size is reduced, but the surface pressure at sliding portions increases requiring more lubricating oil
Solution Approach 1:
The oil reservoir portions are pre-formed on the inner peripheral surface of the differential case by providing weir portions between adjacent seat surfaces. This preliminary preparation of oil storage capacity allows the compact differential gear to maintain adequate lubricating oil supply at sliding portions despite high surface pressures, enabling compact design without compromising lubrication under increased pressure conditions.
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 effectively suppresses lubricating oil shortages, ensuring sufficient lubrication and cooling of sliding portions, allowing for a compact differential gear with improved durability and strength.
Implementation Method 1
distribute lubricating oil in the oil reservoir portion to a sliding portion between the pinion gears and the seat surfaces etc. through rotation of the differential case
Data Source
AI summary
The present disclosure provides a differential gear to be mounted on a vehicle, including a pair of side gears, at least two pinion gears meshed with the side gears, and a differential case that houses the side gears and the at least two pinion gears. Lubricating oil is supplied to and discharged from the inside of the differential case via an opening portion. The differential case includes at least two seat surfaces formed on the inner peripheral surface of the differential case so as to support the pinion gears, weir portions provided between the adjacent seat surfaces and extending in a direction along the rotational direction of the differential case to connect between the adjacent seat surfaces, and an oil reservoir portion formed on the inner peripheral surface by the weir portions so as to be positioned on the opposite side, in the axial direction of the side gears, of the opening portion from the weir portions. Consequently, it is possible to render the differential gear compact by suppressing a shortage of lubricating oil for a sliding portion well.