Dry Sump Warm-Up Strategy for Cold Fluid Viscosity
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Solution Overview
Problem
In vehicle drive units, low-voltage electric main pumps struggle to operate effectively in cold temperatures due to the increased viscosity of fluid, leading to inadequate fluid circulation and lubrication.
Innovation Solution
An electric motor is used to warm the fluid in the dry sump system by operating in a warm-up mode while stationary, heating the fluid to a suitable temperature for the main pump to function efficiently, with the scavenge pump then transferring the warmed fluid to an auxiliary reservoir.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a low voltage electric main pump is used to pump drive unit fluid, then the device complexity and power requirements are reduced, but the pump cannot operate effectively when fluid viscosity increases at low temperatures
Solution Approach 1:
The system performs preliminary warming of the drive unit fluid using the electric motor before normal pump operation begins. The control system activates the electric motor in warming mode to circulate and heat the fluid in the sump, reducing its viscosity to a level where the low voltage main pump can effectively pump it, thus ensuring reliable operation in cold conditions
Solution Approach 2:
The system changes the temperature parameter of the drive unit fluid by using the electric motor to heat it during cold conditions. By increasing the fluid temperature, its viscosity decreases, enabling the low voltage main pump to operate reliably. The control system monitors and manages this parameter change through different operational modes
2Reliability
If the electric motor operates in warm-up mode to heat the fluid, then the fluid viscosity is reduced for effective pumping, but the vehicle remains stationary and time is lost
Solution Approach 1:
The system applies partial warming action by operating the electric motor in warming mode for a limited duration or at reduced power levels sufficient to reduce fluid viscosity to an acceptable range, rather than excessive heating. This partial action achieves the necessary fluid temperature reduction in viscosity without unnecessarily extending the stationary period
Solution Approach 2:
The control system uses feedback from temperature sensors and operational conditions to determine when sufficient warming has occurred. Based on this feedback, the system transitions from warming mode to normal operation mode, minimizing the time the vehicle remains stationary while ensuring the fluid is warm enough for effective pumping
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
Ensures the fluid is warmed sufficiently for the main pump to operate effectively, maintaining lubrication and fluid circulation in the drive unit, even at low temperatures, thereby enhancing the operational reliability of the drive unit.
Implementation Method 1
The electric motor is configured to heat the drive unit fluid disposed within the main sump in the warm-up mode
Implementation Method 2
the electric motor to churn the fluid so that the fluid is warm enough to be pumped by a main pump
Data Source
AI summary
A drive unit, method, and control system are provided that warm drive unit fluid in a drive unit having a main pump, a scavenge pump, and an electric motor for powering an axle of a vehicle. The control system and method are configured to fill a main sump of the drive unit with drive unit fluid to a predetermined fill level. In a warm-up mode, the method and control system operate the electric motor to heat the drive unit fluid within the main sump while the vehicle is stationary and the electric motor is at least partially disposed in the drive unit fluid within the main sump. Further in the warm-up mode, the method and control system are configured to operate the scavenge pump to pump the drive unit fluid from the main sump into an auxiliary reservoir after the drive unit fluid has been heated by the electric motor.