Temperature-Responsive Variable Flow Orifice for Hydraulic Systems
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Solution Overview
Problem
Automatic transmissions face sluggish or non-responsive shift times in cold conditions due to increased hydraulic fluid viscosity, which current solutions attempt to address by increasing fluid pressure, but this comes with undesirable costs and packaging issues.
Innovation Solution
A variable flow orifice using a shape memory alloy that adjusts its size based on temperature, increasing flow rate during cold conditions by expanding and returning to normal size at elevated temperatures, thus optimizing clutch actuation response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If fixed diameter orifices are used in hydraulic circuits, then manufacturing is simple and device complexity is low, but hydraulic flow is restricted during cold conditions leading to sluggish shift times
Solution Approach 1:
The patent applies the dynamics principle by transforming the fixed orifice into a variable orifice that changes its flow characteristics based on temperature. The shape memory alloy orifice dynamically adjusts its effective flow area in response to temperature changes, being more open during cold conditions to improve flow and transitioning to a restricted state during normal operating conditions for proper hydraulic control.
Solution Approach 2:
The patent implements parameter changes by utilizing the temperature-dependent properties of shape memory alloy. The orifice material undergoes a phase transformation at a specific transition temperature, causing a change in its mechanical properties and thereby altering the effective orifice size. This automatic parameter adjustment resolves the contradiction between needing high flow during cold starts and proper flow restriction during normal operation.
2Speed
If pump pressure is increased to overcome orifice restrictions during cold conditions, then hydraulic flow improves, but pump size and cost increase and fuel efficiency decreases
Solution Approach 1:
Instead of changing the pump pressure parameter, the patent changes the orifice flow resistance parameter through temperature-dependent material properties. The shape memory alloy orifice automatically adjusts its effective size based on temperature, reducing flow resistance during cold conditions without requiring increased pump pressure, thereby maintaining fuel efficiency.
Solution Approach 2:
The patent replaces the mechanical solution of increasing pump pressure with a material science-based solution using shape memory alloys. The passive, temperature-responsive material substitution eliminates the need for active pressure control mechanisms and the associated energy consumption, while still achieving the desired hydraulic flow improvement during cold conditions.
3Speed
If pump size is increased to provide higher pressure during cold conditions, then hydraulic flow improves, but packaging size and cost increase
Solution Approach 1:
The patent changes the flow resistance parameter of the orifice rather than increasing pump capacity. The shape memory alloy orifice's temperature-dependent phase transformation automatically adjusts its effective size, allowing adequate flow during cold conditions with the existing pump size, thus avoiding increased packaging volume and cost.
Solution Approach 2:
The patent extracts the flow control function from the pump system and relocates it to the orifice component itself. By embedding the temperature-responsive flow regulation capability directly in the orifice material, the system eliminates the need for a larger pump, maintaining compact packaging while achieving the desired hydraulic performance across all temperature conditions.
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
Improves transmission response time during cold starts by enhancing hydraulic fluid flow without the need for active control or increased pump size, maintaining cost-effectiveness and packaging efficiency.
Implementation Method 1
The variable flow orifice includes a shape memory alloy that selectively increases and decreases the size of an orifice. The deformation of the shape memory alloy, and therefore the size of the orifice, is a function of the temperature of the transmission.
Data Source
AI summary
A variable flow orifice for a hydraulic control system in a transmission includes a shape memory alloy that selectively increases and decreases the size of an orifice. The deformation of the shape memory alloy, and therefore the size of the orifice, is a function of the temperature of the transmission. During cold conditions the orifice size is increased and during normal operating conditions the size of the orifice is decreased.