Automatic Transmission Hydraulics Using Motor Current for Lube Flow
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Solution Overview
Problem
Existing hydraulic systems for automatic transmissions require complex and costly sensor units to determine the secondary flow rate for lubrication and cooling, which is inefficient and prone to errors.
Innovation Solution
A method that uses an electrically driven pump with a controllable valve unit to adjust the hydraulic resistance between the primary and secondary circuits, allowing for the determination and adjustment of the secondary flow rate based on the input current and speed of the electric motor, eliminating the need for a complex sensor unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensor unit for measuring pressure and flow rate is used to determine the secondary flow rate, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical sensor unit (pressure and flow rate sensors) with an electrical measurement system. The electronic control unit determines the secondary flow rate by measuring the electrical input current to the electrically driven pump and calculating flow based on electrical parameters, thereby eliminating complex mechanical sensors while maintaining measurement capability
Solution Approach 2:
The patent introduces the electrical input current as an intermediary measurement parameter. Instead of directly measuring pressure and flow rate with complex sensors, the system measures the electrical current consumed by the pump, which serves as a proxy indicator for the secondary flow rate delivered to the automatic transmission
2Manufacturing precision
If the valve unit adjusts hydraulic resistance to control secondary flow rate, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The valve unit performs multiple functions: it controls the connection between primary and secondary circuits, adjusts hydraulic resistance to regulate secondary flow rate, and enables the system to operate in different modes (connected/disconnected states). This multi-functionality reduces the need for separate dedicated components for each function
Solution Approach 2:
The patent controls the secondary flow rate by dynamically changing the hydraulic resistance parameter of the valve unit. The electronic control unit adjusts the valve position to modify the resistance characteristic, thereby precisely controlling the amount of lube oil delivered to the automatic transmission without requiring complex flow control mechanisms
3Productivity
If the electric motor speed is adjusted to control secondary flow rate, then productivity is improved, but use of energy increases
Solution Approach 1:
The patent employs dynamic speed control of the electrically driven pump motor based on real-time operating conditions. The electronic control unit continuously adjusts the motor speed to match the actual lube oil demand of the automatic transmission, enabling the system to operate efficiently across varying conditions rather than running at constant high speed
Solution Approach 2:
The system uses feedback control where the electronic control unit monitors the electrical input current (which correlates with pump output) and adjusts the motor speed accordingly. This closed-loop control ensures the pump delivers the required lube oil flow while minimizing energy consumption by avoiding unnecessary high-speed operation
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 method enables efficient and precise adjustment of the lube oil amount in the secondary circuit, ensuring sufficient supply to the automatic transmission while minimizing sensor expenditure and preventing undersupply, thus avoiding potential transmission failures.
Implementation Method 1
at least one gear pump (21), which can be driven by an electric motor (22)
Implementation Method 2
the hydraulic resistance between the two is changable by the valve unit (3)
Implementation Method 3
at least one gear pump (21), which can be driven by an electric motor (22)
Data Source
AI summary
A method for operating a hydraulic system for an automatic transmission includes determining a defined primary pressure value (p_PE) to be adjusted based on a measurement of an input current (I_22) of an electric motor and also includes adjusting a secondary flow rate (Q_SZ) to be adjusted based on calculation and adjustment of a target speed (n_Z) of the electric motor.