Hydraulic Fan Drive System Torque Control
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Solution Overview
Problem
Debris collection vehicles face limitations in fan performance due to torque constraints from auxiliary engines and increased equipment wear from operating hydraulic motors and pumps at maximum speeds.
Innovation Solution
A hydraulic fan drive system with a closed loop circuit, variable displacement hydraulic pump and motor, and a control valve to adjust output based on pressure, allowing for adjustable torque and speed, powered by either the primary or auxiliary power plant, and optionally controlled by an electronic controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the fan is directly driven by an auxiliary engine via a gear box, then the system structure is simple, but the fan performance is limited by the torque that can be produced by the auxiliary engine
Solution Approach 1:
The patent applies hydraulic principles by using a hydraulic pump to drive a hydraulic motor, which in turn drives the fan. This hydraulic transmission system overcomes the torque limitations of direct engine coupling, as hydraulic systems can multiply torque through pressure differential and piston area ratios, enabling the fan to achieve higher performance without increasing auxiliary engine size.
Solution Approach 2:
The patent employs a variable displacement hydraulic pump that can change its displacement parameter based on system demands. This allows the system to optimize the balance between pump speed and motor torque output, providing high torque at low speeds when needed for fan operation while maintaining system efficiency, thereby resolving the contradiction between structural simplicity and fan performance capability.
2Power
If a fixed displacement hydraulic motor is used to drive the fan, then the fan can achieve required performance, but the motor and pump must operate at or over their maximum rated speeds, decreasing equipment life
Solution Approach 1:
The patent uses a variable displacement hydraulic pump instead of a fixed displacement pump. This dynamic system can adjust its displacement to match the actual hydraulic demand of the motor-fan system. By varying the pump displacement, the system can operate the pump and motor at optimal speeds below their maximum rated values while still delivering the required fan performance, thereby extending equipment life and improving reliability.
Solution Approach 2:
The system incorporates a control valve that responds to pressure feedback from the hydraulic circuit. When the hydraulic motor reaches the speed or torque required for optimal fan operation, the control valve adjusts to reduce pump displacement, preventing the motor and pump from operating continuously at maximum rated speeds. This feedback mechanism protects equipment and extends operational life while maintaining fan performance.
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
The system enhances fan performance, reduces equipment wear, decreases maintenance and emissions, and extends the operational life of hydraulic components, while offering a more versatile and cost-effective solution compared to conventional systems.
Implementation Method 1
a hydraulic pump disposed within the closed loop circuit and having an inlet and an outlet
Implementation Method 2
a hydraulic motor disposed within the closed loop circuit... The hydraulic motor can be provided with an output shaft, an inlet in direct fluid communication with the variable displacement pump outlet, and an outlet in direct fluid communication with the variable displacement pump inlet
Implementation Method 3
a fan coupled to the output shaft of the hydraulic motor... such that the fan can draw a vacuum condition within the tank or hopper
Data Source
AI summary
A debris collection vehicle having an enclosed volume for collecting debris and a hydraulic fan drive system for creating vacuum condition in the enclosed volume is disclosed. In one embodiment, the hydraulic fan system includes a closed loop hydraulic circuit, a variable displacement hydraulic pump disposed within the closed loop circuit, and a hydraulic motor disposed within the closed loop circuit. The hydraulic fan drive system can also include an electronic or hydraulically actuated control valve constructed and arranged to adjust the output of the hydraulic motor via a displacement actuator based on pressure in the closed loop hydraulic circuit.