Gearwheel Cooling Layout for High-Speed EV Transmissions
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Solution Overview
Problem
Electrically operated vehicles face challenges with lubrication and cooling of gearwheels due to higher rotational speeds, which cause cooling fluid to be thrown outward, preventing efficient cooling.
Innovation Solution
A gearwheel arrangement where cooling fluid is directed radially inwardly toward the gear teeth, utilizing centrifugal forces during rotation to ensure efficient cooling, with optional conduits and nozzles for fluid guidance, allowing for efficient cooling even at high rotational speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling fluid is provided from a radially outer position (cooling fluid bath or sump), then cooling is efficient at low rotational speeds, but at high rotational speeds the cooling fluid is thrown outward and cooling efficiency deteriorates
Solution Approach 1:
The patent inverts the conventional cooling approach by providing cooling fluid from a radially inner position instead of a radially outer position. The cooling fluid is directed toward radially inwardly facing surfaces of the gear tooth section, so that centrifugal forces during rotation press the cooling fluid against these surfaces, maintaining effective cooling contact even at high rotational speeds where conventional outer-position cooling would fail.
2Power
If gearwheels rotate at high speeds in electric vehicles, then propulsion performance is improved, but lubrication and cooling efficiency deteriorates due to cooling fluid being thrown outward
Solution Approach 1:
The patent applies inversion by reversing the radial position of cooling fluid provision from outer to inner. This allows the system to maintain reliable lubrication and cooling under high-speed operation conditions required for electric vehicle propulsion performance.
Solution Approach 2:
The patent converts the harmful effect of centrifugal forces (which throw cooling fluid outward at high speeds) into a beneficial effect by directing cooling fluid inwardly. The centrifugal forces then press the cooling fluid against the radially inwardly facing surfaces, enhancing cooling effectiveness precisely when rotational speeds are highest.
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 solution effectively maintains efficient cooling of gearwheels during high-speed operation by directing cooling fluid inwardly, ensuring effective lubrication and heat dissipation, even in electric vehicles with large gear ratios.
Implementation Method 1
the rotation of the gearwheel results in cooling fluid being pressed toward the radially inwardly facing surface, radially inside of the gear teeth
Data Source
AI summary
A gearwheel arrangement for a transmission of a vehicle, including:a gearwheel configured to be rotatable about an axis of rotation (A), the gearwheel including a gearwheel body and an annular gear tooth section extending around the gearwheel body, the gear tooth section including a plurality of external gear teeth, wherein at least a part of the gear tooth section extends past a radially outer portion of the gearwheel body in an axial direction (A) of the gearwheel, so that at least one radially inwardly facing surface is provided opposite of the external gear teeth,means for guiding cooling fluid toward the at least one radially inwardly facing surface so as to cool the gear tooth section during rotation of the gearwheel about the axis of rotation.