Differential Oil Shield Reducing Lubricant Churning
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Solution Overview
Problem
Modern automotive axle assemblies experience 'oil paddling' issues due to the rotation of differential components through a liquid lubricant, leading to lubricant churning, foaming, and heat generation, which adversely affect lubrication and efficiency.
Innovation Solution
An axle assembly design incorporating an oil shield that rotates with the differential case, covering radially outward rib members and threaded fastener heads to prevent direct contact with the lubricant, thereby reducing fluid churning and friction losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the differential assembly rotates through the liquid lubricant in the sump, then the lubricant can cling to and lubricate various parts of the axle assembly, but this causes oil paddling, churning, and heat generation that adversely affect lubrication efficiency
Solution Approach 1:
The oil shield acts as an intermediary component between the rotating differential assembly and the liquid lubricant. It selectively allows beneficial lubricant contact with gears and bearings while blocking harmful contact with the rib members and fastener heads, thus resolving the contradiction between maintaining lubrication effectiveness and reducing energy loss from churning
Solution Approach 2:
The oil shield creates different lubrication zones: areas where lubricant contact is permitted (gears, bearings) and areas where contact is prevented (rib members, fastener heads). This local differentiation allows the system to maintain necessary lubrication while eliminating parasitic churning, addressing the contradiction between reliable lubrication and energy efficiency
2Loss of energy
If the ring gear is surrounded by a shroud in close proximity, then fluid churning is greatly reduced, but lubricant can collect in the channel and the churning is not completely eliminated
Solution Approach 1:
The oil shield serves as a controlled intermediary that allows selective lubricant interaction. Unlike the enclosed shroud that completely blocks contact, the oil shield permits beneficial lubricant access to gears and bearings while preventing harmful contact with non-lubricated surfaces, thus maintaining both low churning and adequate lubrication
Solution Approach 2:
The oil shield rotates with the differential assembly, dynamically managing lubricant interaction. As the shield rotates, it continuously presents different surfaces to the lubricant, allowing controlled contact in some areas while preventing contact in others, thereby maintaining both energy efficiency and lubrication effectiveness
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 oil shield effectively minimizes lubricant churning and friction, enhancing lubrication efficiency by preventing direct contact between rotating components and the lubricant, thus reducing parasitic friction and heat generation.
Implementation Method 1
The oil shield covers a least a radially outward portion of the circumferentially discontinuous features so that the at least the radially outward portion of the circumferentially discontinuous features does not directly contact the liquid lubricant in the lubricant sump when the differential assembly rotates about the rotational axis
Data Source
AI summary
An axle assembly that includes a housing assembly, a lubricant and a differential assembly. The housing assembly defines a differential cavity with a lubricant sump into which the liquid lubricant is received. The differential assembly is mounted in the differential cavity for rotation about a rotational axis and includes a differential case, a ring gear, a gear set and an oil shield. The differential case has a body, which defines a gear cavity into which the gear set is received, and a flange that is coupled to the body and includes a flange face. The ring gear is coupled to the flange. The oil shield is coupled for rotation to the differential case and covers a least a radially outward portion of the circumferentially discontinuous features so that they do not directly contact the liquid lubricant in the lubricant sump when the differential assembly rotates about the rotational axis.