Hydraulic Fan Control Using Shape Memory Alloy Spring
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hydraulic fan control systems using thermally pilot-controlled bypass pressure-limiting valves suffer from poor proportional behavior, inadequate temperature control range, and aging issues with wax elements, leading to inefficient fan speed regulation and delayed cooling capacity response.
Innovation Solution
The use of a compression spring made from a shape memory alloy in the thermal valve, combined with additional thermocouples and a cooler thermal bypass valve, allows for flexible and energy-efficient fan speed control, with the shape memory alloy's temperature-dependent force-stroke characteristic enabling precise regulation of cooling capacity and long-term reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a wax element is used as the adjusting actuator in the thermal valve, then the fan control is purely thermal with no sensors or electrical control technology needed, but the fan motor does not run when the oil is cold and then runs at maximum speed even with a very small temperature range exceeded, resulting in poor proportional behavior
Solution Approach 1:
The patent applies parameter changes by using a compression spring with modified material properties (shape memory alloy or temperature-dependent material) to achieve continuous fan speed adjustment. The spring's force characteristic is changed from discrete (wax element) to continuous, allowing the fan motor to operate proportionally across a temperature range rather than switching between off and maximum speed only.
Solution Approach 2:
The patent implements dynamics by enabling the fan motor speed to dynamically adjust continuously with temperature changes. The compression spring provides a progressive force response that allows the bypass valve to open gradually, creating a dynamic control characteristic where fan speed follows oil temperature continuously rather than in discrete steps.
2Device complexity
If only the inlet temperature is used to control the fan speed, then the control system is simple, but the fan speed increase is delayed if the oil temperature in the working hydraulics return line rises rapidly
Solution Approach 1:
The patent applies segmentation by using multiple temperature sensors positioned at different locations in the hydraulic system (inlet line and return line). This divides the temperature monitoring function into separate measurement points, allowing the control system to detect temperature rises in different parts of the system independently and respond more quickly to actual cooling needs.
Solution Approach 2:
The patent implements preliminary action by placing temperature sensors in strategic locations that detect temperature changes before they affect the main oil tank. The return line sensor provides early warning of heating in the working hydraulics, allowing the fan to increase speed in advance before the bulk oil temperature rises, thus reducing the delay in cooling response.
3Device complexity
If a wax element is used in the thermal valve, then the control is compact and energy-efficient, but the expansion element shows signs of aging that lead to significant deterioration in lifting and power properties, resulting in deteriorated fan speed control
Solution Approach 1:
The patent applies this principle by replacing the aging-prone wax element with a compression spring that has superior long-term stability. While the spring may require initial adjustment, it does not exhibit the same degradation characteristics as wax elements, effectively creating a more durable, long-lasting control component that maintains its properties over the system's operational life.
Solution Approach 2:
The patent changes the material parameter of the adjusting actuator from wax (organic, aging-prone) to metal spring (inorganic, stable). This parameter change in material composition eliminates the aging issue while maintaining the compact, purely thermal control architecture. The spring's elastic properties provide consistent force output over time without the deterioration seen in wax elements.
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 solution provides a more precise and energy-efficient fan speed control that adapts to oil temperature changes, ensuring adequate cooling capacity and extending the system's operational lifespan by avoiding the limitations of wax elements and improving fan speed control over a broader temperature range.
Implementation Method 1
the compression spring consists of a shape memory alloy which has a temperature-dependent force-stroke characteristic
Implementation Method 2
The thermal valve mentioned has an expanding material element as the adjusting actuator, whereby commercially available wax elements are predominantly used today, with the expanding material element expanding from a certain temperature and increasing the force on the pilot control of the pressure valve
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a hydraulic fan control, comprising at least one fan motor (10), a pressure supply device, in particular a hydraulic pump (12), for supplying the fan motor (10) with a pressure medium, in particular in the form of hydraulic oil, and a thermostatic valve (40) controlling the fan motor speed, characterized in that the thermostatic valve (40) has an energy storage device, preferably in the form of a compression spring (48), consisting of a shape memory alloy.