Final Drive Motor Positioning and Lubrication
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Solution Overview
Problem
Existing final drives for vehicles are vulnerable to damage from incoming stones, dirt, and water due to the exposure of electric motors and reduction gears, leading to durability issues and the need for separate lubrication systems.
Innovation Solution
A final drive design with an electric motor positioned outside and above the casing, hidden from road debris, and a cam mechanism that converts rotational energy into axial pressure to operate a clutch, while a lubricant passage ensures adequate lubrication for the reduction gears within a single chamber housing the differential gear set, clutch, and gear set.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric motor is disposed below the casing to allow lubricant oil supply to reduction gears, then lubrication is improved, but the electric motor is exposed to incoming stones, dust and water from the road
Solution Approach 1:
The electric motor is repositioned from a vertical arrangement (below the casing) to a horizontal arrangement (above and behind the casing). This spatial reconfiguration in another dimension allows the motor to remain protected from road debris while still receiving lubrication through the lubricant passage that extends horizontally to the reduction gears.
2Object-affected harmful factors
If the electric motor and reduction gears are arranged above the casing to protect from road debris, then durability is improved, but lubricant oil within the casing cannot sufficiently reach the reduction gears
Solution Approach 1:
A lubricant passage acts as an intermediary element, extending from the lubricant reservoir within the casing to the reduction gears positioned above the casing. This passage serves as a conduit that bridges the spatial gap, allowing lubricant oil to reach the reduction gears without requiring them to be positioned below the casing where road debris can access them.
3Reliability
If separate casings are used for reduction gears and final drive to enable independent lubrication, then lubrication is improved, but fixation between casings and shaft positioning becomes complex and dust can intrude through couplings
Solution Approach 1:
The patent merges the reduction gears with the final drive casing, eliminating the need for separate casings. The reduction gears are positioned within the same casing as the final drive components, allowing a single lubrication system to service all components. This unified approach reduces the complexity of fixation between multiple casings and eliminates dust intrusion risks through coupling interfaces.
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 enhances durability by protecting the electric motor from road debris and ensures effective lubrication of all components within the final drive, preventing dust intrusion and maintaining gear engagement stability.
Implementation Method 1
a cam mechanism comprising a cam plate fixed from rotation about the rotational axis and so disposed as to move along the rotational axis to exert a fastening force on the clutch and a cam gear rotatable about the rotational axis, the cam mechanism for converting rotation of the cam gear into a pressure force along the rotational axis of the cam plate
Data Source
AI summary
A final drive mounted on a vehicle is comprised of: a differential gear set; a clutch rotatable about a rotational axis and combined with the differential gear set; a cam mechanism comprising a cam plate fixed from rotation about the rotational axis and so disposed as to move along the rotational axis to exert a fastening force on the clutch and a cam gear rotatable about the rotational axis, the cam mechanism for converting rotation of the cam gear into a pressure force on the cam plate; a gear set so meshed with the cam gear to rotate the cam gear; a casing housing the differential gear set, the clutch, the cam mechanism and the gear set in a single chamber; and a motor so disposed outside and above the casing as to hide behind the casing from a road and combined with the gear set.