Refuse Vehicle Hydraulic Pump Torque Limiting Under High Load
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Solution Overview
Problem
Refuse vehicles face challenges in preventing over-torqueing and stalling of hydraulic pumps during increased power consumption, which can lead to motor damage and inefficiencies in waste collection operations.
Innovation Solution
A torque limiting hydraulic circuit system that includes sensors to monitor pressure and swashplate position, and a spool valve to divert hydraulic fluid and adjust the swashplate angle, reducing pump output and torque when pressure exceeds thresholds, thereby preventing over-torqueing and stalling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the hydraulic pump operates at high power output to meet increased waste collection demands, then productivity is improved, but the risk of over-torqueing and motor damage increases
Solution Approach 1:
The control system continuously monitors hydraulic circuit pressure and pump operating parameters, comparing them against predetermined thresholds. When pressure exceeds the threshold or the pump approaches maximum torque capacity, the system automatically adjusts pump displacement to reduce torque output, preventing over-torqueing and motor damage while maintaining optimal productivity during normal operation
Solution Approach 2:
The variable displacement pump's operating parameters (displacement, torque, flow rate) are dynamically adjusted based on real-time hydraulic circuit conditions. The control system modifies these parameters in response to pressure changes and load conditions, allowing the pump to operate efficiently across varying demands without exceeding torque limits
2Force
If the pump operates at maximum torque capacity to handle heavy loads, then force output is improved, but the risk of stalling and component failure increases
Solution Approach 1:
The control system monitors pump torque capacity and hydraulic circuit pressure in real-time. When the pump approaches maximum torque capacity or pressure exceeds thresholds, the system automatically reduces pump displacement to prevent stalling, ensuring the pump operates within safe torque limits while maintaining sufficient force output for waste collection operations
3Productivity
If the pump operates without torque limits to maximize productivity, then waste collection efficiency is improved, but energy loss increases due to over-torqueing and stalling
Solution Approach 1:
The pump's displacement and torque output are dynamically adjusted based on actual hydraulic circuit demands. The control system optimizes energy efficiency by matching pump output to load requirements, preventing energy waste from over-torqueing and stalling while maintaining sufficient productivity for waste collection operations
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 effectively prevents pump stalling and motor damage by reducing torque and maintaining efficient hydraulic pump performance during high load conditions, ensuring continuous operation and reducing the risk of component failure.
Implementation Method 1
A variable displacement pump is positioned within or adjacent the vehicle body and is configured to pump hydraulic fluid from a hydraulic fluid reservoir into a high pressure line of a hydraulic circuit on the refuse vehicle
Implementation Method 2
the valve directs fluid from the high pressure line through the valve and into a lower pressure line within the hydraulic circuit that reduces the hydraulic pressure within the high pressure line and adjusts an output parameter of the variable displacement pump
Data Source
AI summary
A refuse vehicle includes a chassis and a vehicle body. A variable displacement pump is positioned within the vehicle body and is configured to pump hydraulic fluid from a hydraulic fluid reservoir into a high pressure line of a hydraulic circuit. A lifting system on the vehicle includes at least one actuator in fluid communication with the variable displacement pump, which delivers pressurized hydraulic fluid from the hydraulic fluid reservoir to the actuator through the high pressure line to adjust a position of the actuator. A valve is positioned downstream of the variable displacement pump. In a first valve position, the valve restricts flow outward from the high pressure line. In a second valve position, the valve directs fluid from the high pressure line into a lower pressure line to reduce a hydraulic pressure within the high pressure line and adjust an output parameter of the variable displacement pump.