Hydraulic Control System for Electric Motor Cooling
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Solution Overview
Problem
Existing hydraulic control systems for motor vehicle powertrains face challenges in efficiently managing clutch engagement and cooling flow to the pump motor stator, particularly in engine start-stop cycles, where pressure drops and heat generation occur, leading to inefficiencies and operational instability.
Innovation Solution
A hydraulic control system that includes a hydraulic pump driven by an electric motor, a normally high, variable force solenoid valve controlling a pressure regulator valve and a stator shift valve, which simultaneously manages fluid flow to a transmission oil cooler and a dog clutch, ensuring optimal pressure and cooling for the electric motor stator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an electric motor is used to power the hydraulic pump, then the pump can operate during engine stop and fluid output can be controlled, but significant heat is generated during high speed operation
Solution Approach 1:
The patent extracts the cooling function as a separate controllable flow path from the main hydraulic system. The third valve specifically directs hydraulic fluid to cool the electric motor stator, separating cooling needs from clutch actuation needs. This allows independent control of cooling flow regardless of clutch engagement state.
Solution Approach 2:
The system uses periodic or conditional activation of cooling flow based on operating conditions. The control system activates cooling flow during high speed operation when heat generation occurs, and reduces or stops cooling flow during low speed operation, creating a periodic or conditional cooling pattern that matches thermal generation.
2Device complexity
If a single solenoid valve controls both clutch engagement and cooling flow, then system complexity is reduced, but control precision for simultaneous clutch and cooling requirements is compromised
Solution Approach 1:
The patent segments the control function across three specialized valves: first valve for pressure regulation, second valve for clutch engagement control, and third valve for cooling flow control. This segmentation allows each valve to be optimized for its specific function while working together under unified solenoid control, achieving both simplicity and precision.
Solution Approach 2:
The solenoid valve assembly serves multiple functions by controlling different valve positions based on operating conditions. The same solenoid actuator can direct fluid to engage clutches, activate cooling, or both simultaneously, providing multi-functionality without requiring separate solenoids for each function.
3Ease of operation
If hydraulic fluid flow is directed to the dog clutch for engagement, then clutch actuation is achieved, but cooling flow to the electric motor stator is reduced
Solution Approach 1:
The patent segments the hydraulic control into separate pathways: the second valve controls clutch engagement while the third valve controls cooling flow. This segmentation allows independent control of clutch actuation and cooling, enabling simultaneous operation without compromising either function.
Solution Approach 2:
The system dynamically adjusts fluid distribution based on real-time operating conditions. The control system can shift fluid flow priorities dynamically - directing more flow to clutch engagement during shifting operations, or to cooling during high-speed operation - adapting the hydraulic distribution to match instantaneous system needs.
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 system reduces hydraulic fluid consumption while providing improved cooling and operational stability by selectively controlling fluid flow to the dog clutch and electric motor stator, addressing issues of pressure drop and heat management during engine start-stop cycles.
Implementation Method 1
The solenoid valve is a normally high, variable force solenoid valve which provides a fluid control signal to the second and third valves
Implementation Method 2
Since the pump now includes an electric motor, during high speed operation it will generate significant heat
Implementation Method 3
it controls fluid flow to the stator of the electric pump motor to provide cooling
Data Source
AI summary
A hydraulic control system includes a hydraulic pump driven by an electric motor, a solenoid valve having an output that controls the positions of a pressure regulator valve and a third, stator shift valve. The solenoid valve is a normally high, variable force solenoid valve which provides a control signal to the second and third valves. The second, pressure regulator valve is a multiple port valve which controls hydraulic fluid flow both to a transmission oil cooler (ATOC) and to an exhaust port, thereby maintaining a desired system pressure. The third, stator shift valve is also a multiple port valve and it controls fluid flow to the stator of the electric pump motor to provide cooling and to a dog clutch of the transmission to disengage it.