Automatic Transmission Drag Torque Reduction via Temperature-Dependent Aperture
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Solution Overview
Problem
Automatic transmissions face challenges in reducing drag torque, particularly in the lower temperature range of the NEDC consumption cycle, where existing systems struggle to optimize lubrication and cooling efficiently due to the viscous properties of cooling oil, leading to suboptimal fuel economy and emissions performance.
Innovation Solution
A device with a hydraulic controller in automatic transmissions, featuring a parallel connection of a pressure relief valve and a temperature-dependent, switchable aperture, ensures minimum lubrication and cooling at low temperatures and allows reduction in cooling and lubricating oil quantity at high temperatures and pressures, thereby reducing drag torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the quantity of cooling and lubricating oil is reduced at low temperatures, then drag torque is reduced, but lubrication and cooling efficiency deteriorates
Solution Approach 1:
The patent implements dynamic control of oil flow through a switchable aperture (10) that responds to temperature changes. At low temperatures, the aperture closes to reduce oil flow and drag torque, while at high temperatures, it opens to ensure sufficient lubrication and cooling. This dynamic adaptation resolves the contradiction by adjusting the system state based on operating conditions.
Solution Approach 2:
The patent changes the physical parameter of oil flow quantity based on temperature conditions. Through the temperature-dependent switchable aperture, the system transitions between different flow states (reduced flow at low temperature, increased flow at high temperature), thereby optimizing the balance between drag torque reduction and lubrication efficiency.
2Reliability
If the quantity of cooling and lubricating oil is increased at high temperatures, then lubrication and cooling efficiency is improved, but drag torque increases
Solution Approach 1:
The switchable aperture (10) dynamically opens at high temperatures to increase oil flow for improved lubrication and cooling efficiency. Simultaneously, the pressure relief valve (2) modulates excess flow to prevent unnecessary drag torque increase, achieving a dynamic balance between these conflicting requirements.
Solution Approach 2:
The pressure relief valve (2) extracts or diverts excess oil flow when it exceeds what is necessary for lubrication and cooling. This separation of functions allows the system to maintain sufficient lubrication while removing the portion of oil flow that would otherwise create unnecessary drag torque.
3Loss of energy
If a temperature-dependent switchable aperture is added, then oil flow is optimized for drag reduction, but device complexity increases
Solution Approach 1:
The switchable aperture (10) is designed to automatically respond to temperature changes without external control signals. The temperature-dependent actuation mechanism self-regulates oil flow based on thermal conditions, eliminating the need for complex electronic sensors or control systems while achieving drag torque optimization.
Solution Approach 2:
The patent uses hydraulic principles to implement the temperature-dependent flow control. The switchable aperture utilizes thermal expansion or hydraulic actuation mechanisms that leverage fluid properties to automatically modulate flow, providing an elegant solution that avoids electronic complexity while achieving the desired drag reduction.
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 solution effectively reduces drag torque in automatic transmissions by optimizing oil flow based on temperature and pressure conditions, ensuring efficient lubrication and cooling, especially in the NEDC consumption cycle, thereby enhancing fuel economy and emissions compliance.
Implementation Method 1
a pressure relief valve in the direction of flow to the radiator that opens against a spring force above a pressure threshold
Implementation Method 2
Due to the viscous properties of cooling oil, lower volume flows arise at low temperatures than at high temperatures
Implementation Method 3
a temperature-dependent, switchable aperture opening above a temperature threshold
Implementation Method 4
a radiator for the heat dissipation of the operating medium
Data Source
AI summary
A drag torque reduction device for an automatic transmission includes a hydraulic controller with a radiator. In one embodiment, the drag torque reduction device also includes a parallel connection of a pressure relief valve, a constant aperture and a temperature-dependent, switchable aperture positioned upstream of the radiator. In another embodiment, the drag torque reduction device includes an overflow cooling oil diversion with a temperature-dependent, switchable aperture and a pressure relief valve that is positioned upstream of the radiator.