EOP Motor Coil Heating for Transmission Oil Viscosity

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Solution Overview

Problem

In ultra-low temperature environments, the viscosity of transmission oil in hybrid vehicles increases, leading to delayed vehicle startups due to unstable hydraulic pressure, necessitating over-specification of the electric oil pump (EOP) and oil pump unit (OPU), which raises manufacturing costs.

Innovation Solution

The method and apparatus utilize the motor coil of the EOP as a heater, controlled by a controller (TCU) to heat the transmission oil before vehicle startup, using a field-effect transistor (FET) controller to apply current to the motor coil, thereby adjusting the oil viscosity and ensuring stable startup conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the EOP and OPU are designed with over-spec capacity to handle high torque/high current requirements in ultra-low temperature environments, then the vehicle startup reliability is improved, but the manufacturing cost increases

Engineering Contradiction:

Improvevehicle startup reliabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by heating the transmission oil before the EOP starts operating in ultra-low temperature environments. The heating element pre-warms the oil to reduce its viscosity, ensuring that when the EOP starts, the oil is already in a suitable viscosity range. This eliminates the need to design the EOP with over-spec capacity, as the oil viscosity issue is resolved beforehand.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the temperature parameter of the transmission oil from ultra-low temperature to a warmer temperature before the EOP operates. By controlling the oil temperature to maintain viscosity within an appropriate range, the system avoids the need for oversized EOP components, thereby reducing manufacturing costs while ensuring reliable startup.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If the EOP is designed with high torque and high current capacity for ultra-low temperature operation, then the oil viscosity stability is improved, but the motor and power module sizes increase

Engineering Contradiction:

Improveoil viscosity stabilityVSAvoidmotor and power module size

Core Design Contradiction:

Stability of the object's compositionVSVolume of moving object

Solution Approach 1:

The heating element performs preliminary action by warming the transmission oil before the EOP operates in cold conditions. This pre-heating ensures the oil viscosity is already stabilized at an appropriate level, eliminating the need for the motor and power module to be oversized for cold-temperature viscosity management.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the mechanical approach of using a larger motor and power module to handle cold-temperature viscosity issues with a thermal approach. Instead of mechanically compensating for high viscosity through increased motor capacity, the system uses thermal energy to pre-warm the oil, substituting a thermal field solution for a mechanical field solution.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If the EOP operates without pre-heating the transmission oil in ultra-low temperature environments, then the device complexity is reduced, but the vehicle startup is delayed

Engineering Contradiction:

Improvedevice complexityVSAvoidvehicle startup time

Core Design Contradiction:

Device complexityVSLoss of time

Solution Approach 1:

The patent merges the heating function with the existing EOP system by integrating a heating element into the transmission oil pathway. This combination allows the heating function to be added without requiring a completely separate system, thus minimizing the increase in device complexity while enabling pre-heating to reduce startup time.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The heating element serves multiple functions: it pre-heats the transmission oil to reduce viscosity for faster startup, and can potentially serve as a temperature maintenance device during operation. This multi-functionality justifies the added complexity by providing multiple benefits from a single component.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 approach reduces the need for over-specification of the EOP and OPU, lowering manufacturing costs and ensuring a stable vehicle startup in ultra-low temperatures by optimizing the motor capacity and power module design.

Implementation Method 1

applying a current to a motor coil of the EOP to heat the transmission oil by heat generated from the motor coil

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS11454311B2Method and apparatus for controlling transmission oil temperature

Publication Date: 2022.09.27 HYUNDAI MOTOR CO LTD

AI summary

A method and apparatus for controlling transmission oil temperature are provided. The transmission oil is heated using a motor coil of an electric oil pump (EOP) as a heater before a startup of a vehicle. The method includes applying a current to the motor coil of the EOP configured to operate a transmission of the vehicle to thus heat the transmission oil by heat generated from the motor coil.