Variable-Pitch Axial Fan Pressure Control for Precise Vehicle Cooling
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Solution Overview
Problem
Existing cooling systems for utility vehicles exhibit imprecise closed-loop temperature control behavior due to sluggish reaction of air-cooled vehicle assemblies to cooling air stream changes, leading to overshooting tendencies, and the detection of fan blade deflection on rotating parts is complex.
Innovation Solution
A system utilizing a pressure-operable actuator with a hydraulic or pneumatic operation for pivoting fan blades, combined with a control unit that adjusts the angle of incidence based on temperature feedback and pressure control, incorporating cascaded control loops for precise cooling power adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If temperature-based closed-loop control of the axial fan is used, then cooling power adaptation is achieved, but the control behavior becomes imprecise with overshooting tendencies due to sluggish temperature reaction
Solution Approach 1:
The control system uses the dynamically determined angle of incidence of the fan blades as a preliminary indicator of the cooling air stream's effect on the vehicle assembly. This allows the control to act before the temperature actually changes, predicting the thermal effect and enabling proactive adjustment rather than reactive correction, thus preventing overshooting while maintaining adaptability.
Solution Approach 2:
The system implements feedback by continuously monitoring the angle of incidence of the fan blades and using this information to dynamically adjust the control strategy. The angle of incidence serves as a feedback parameter that reflects the current state of the cooling system, allowing the control unit to optimize cooling power delivery and improve temperature control precision.
2Measurement precision
If sensor-based detection of fan blade deflection is implemented on the rotating fan hub, then closed-loop control of the angle of incidence is achieved, but the technical complexity increases due to the rotating part environment
Solution Approach 1:
Instead of placing sensors directly on the rotating fan hub, the system uses an intermediary approach by detecting the angle of incidence through the position of the actuator or by inferring it from the control signals sent to the actuator. This intermediary method transfers the measurement function from the complex rotating environment to a stationary or easily accessible location, reducing technical complexity while maintaining detection precision.
Solution Approach 2:
The system replaces mechanical sensor-based detection on the rotating hub with an alternative approach that may involve electronic sensing or calculation based on actuator position and control signals. This substitution eliminates the need for complex mechanical sensors in the rotating environment, reducing device complexity while achieving the same measurement objective.
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
Achieves precise closed-loop control of cooling air streams with reduced technical complexity by unambiguously predicting fan blade angles through pressure detection, allowing for targeted cooling power adaptation.
Implementation Method 1
the axial fan has a plurality of fan blades that can be pivoted in terms of an angle of incidence by deflection of a pressure-operable actuator
Implementation Method 2
an axial fan which can be set in rotation by a fan drive and which is used to generate a cooling air stream for impingement on a vehicle assembly that is to be cooled
Data Source
AI summary
A system for operating a cooling device of a utility vehicle includes an axial fan, a temperature sensor, and a control unit. The axial fan can be rotated by a fan drive and is used to generate a cooling air stream for impingement on a vehicle assembly that is to be cooled. The axial fan has a plurality of fan blades that can be pivoted in terms of an angle of incidence by deflection of an actuator. The temperature sensor determines an actual value of a temperature variable that reflects a present operating temperature of the vehicle assembly. The control unit compares the actual value of the temperature variable with a specified setpoint value to output a target value of a control variable provided for the operation of the actuator. The control variable is one of a hydraulic and a pneumatic operation pressure for deflecting the actuator.