Utility Vehicle Hydraulic Control With Open-Loop Noise Reduction
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Solution Overview
Problem
Existing hydraulic systems in battery-powered utility vehicles, such as stand-on loaders and forklifts, face noise issues due to frequent speed variations of motors and pumps in closed-loop control systems, which are distracting for operators and reduce efficiency.
Innovation Solution
An open-loop control system is implemented, where the target speed of the electric motor and pump is set based on operator input, independent of hydraulic pressure, using a microprocessor-based controller to manage the flow of hydraulic fluid through proportional directional control valves, ensuring smooth and quiet operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If closed-loop control system is used to adjust motor and pump speed based on hydraulic pressure, then system adaptability to load changes is improved, but noise fluctuations increase and operator comfort deteriorates
Solution Approach 1:
The control system is segmented into two independent parts: an open-loop component that sets base motor speed based on operator input, and a pressure-compensation component that makes minor adjustments. This segmentation allows the system to maintain adaptability while reducing noise by avoiding frequent speed variations.
Solution Approach 2:
Instead of using closed-loop control that continuously adjusts speed based on pressure feedback (which causes noise), the patent inverts the approach by using open-loop control with predetermined speed settings that are less prone to causing noise fluctuations.
2Stress or pressure
If frequent speed variations are implemented in closed-loop control, then hydraulic pressure regulation is improved, but noise levels increase and distract the operator
Solution Approach 1:
The system implements dynamic pressure compensation through a compensation valve that adjusts flow distribution based on pressure conditions, while the motor speed remains relatively stable. This dynamic adjustment at the valve level achieves pressure regulation without the noise of frequent motor speed changes.
Solution Approach 2:
A compensation valve acts as an intermediary between the motor and the hydraulic actuators, absorbing pressure variations and flow demands without requiring frequent motor speed adjustments, thereby reducing noise while maintaining pressure regulation.
3Object-affected harmful factors
If open-loop control is used to maintain constant motor speed, then noise fluctuations are reduced and operator comfort is improved, but adaptability to varying hydraulic load demands decreases
Solution Approach 1:
The control system is segmented into two independent parts: an open-loop component that sets base motor speed based on operator input, and a pressure-compensation component that makes minor adjustments. This segmentation allows the system to maintain adaptability while reducing noise by avoiding frequent speed variations.
Solution Approach 2:
The system implements dynamic pressure compensation through a compensation valve that adjusts flow distribution based on pressure conditions, while the motor speed remains relatively stable. This dynamic adjustment at the valve level achieves pressure regulation without the noise of frequent motor speed changes.
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 open-loop control system reduces noise fluctuations, improving the operating experience by maintaining consistent motor speed and fluid flow, thus enhancing user comfort and operational efficiency.
Implementation Method 1
an electric motor selectively driving the pump
Implementation Method 2
a pump configured to pressurize and output hydraulic fluid
Implementation Method 3
A first proportional directional control valve is in the first load circuit and communicates with the pump and the controller. The first proportional directional control valve controls a flow of hydraulic fluid to a first hydraulic actuator
Data Source
AI summary
A hydraulic system includes a pump to pressurize and output hydraulic fluid, an electric motor selectively driving the pump, and a controller to selectively control a target speed of the electric motor based on input from an operator control. A proportional directional control valve is in the load circuit and communicates with the pump and the controller. The proportional directional control valve controls a flow of hydraulic fluid to a hydraulic actuator associated with the load circuit such that the flow of hydraulic fluid to the hydraulic actuator is proportional to a signal provided by the controller. The signal is a function of the input from the operator control. Flow of hydraulic fluid to the hydraulic actuator through the proportional directional control valve is varied by the controller making a) variations of the target speed of the motor, and b) variations of the signal to the proportional directional control valve.