Dual-Pump Hydraulic Flow Switching for Multi-Function Machines
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Solution Overview
Problem
Agricultural machines with single fixed displacement hydraulic pumps face inefficiencies due to excess fluid flow being forced through restrictions, leading to power consumption and heat generation when not operating the actuator with the largest fluid requirement, reducing overall system efficiency.
Innovation Solution
A hydraulic system with two fixed displacement pumps and a combined flow control valve that separates or combines their outputs based on the required flow rates of different actuators, allowing efficient fluid distribution and minimizing power wastage by directing excess flow back to the tank when not needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a single fixed displacement pump is used to provide fluid flow to all actuators, then the system can supply the required flow rate for the actuator with the largest fluid requirement, but excess hydraulic fluid is forced through restrictions and pressure relief valves consuming power and generating heat when that actuator is not operating
Solution Approach 1:
The single pump system is segmented into two separate fixed displacement pumps, each capable of independently supplying fluid to different actuators. This segmentation allows the system to activate only the necessary pump for each specific operation, eliminating the energy waste of forcing excess fluid through restrictions when only one actuator is in use.
Solution Approach 2:
The system dynamically switches between different pump configurations using a combined flow control valve that can separate or combine pump outputs. When the first actuator is operating, both pumps can be activated to provide the required high flow rate; when only the second actuator is operating, only the second pump is activated. This dynamic adaptability optimizes energy usage by matching pump output to actual demand.
2Productivity
If a single fixed displacement pump is sized to provide the required flow for the actuator with the largest fluid requirement, then the actuator can be fully supported, but the system efficiency decreases when operating other actuators with smaller fluid requirements
Solution Approach 1:
The oversized single pump is segmented into two appropriately sized pumps. The first pump is sized to match the flow requirements of the first actuator, and the second pump is sized to match the flow requirements of the second actuator. This eliminates the inefficiency of running an oversized pump at partial load and forces excess fluid through restrictions.
Solution Approach 2:
The system changes the operational parameters by switching between different pump combinations based on which actuator is active. When the first actuator operates, both pumps run at optimal parameters; when the second actuator operates, only the second pump runs at its optimal parameters. This parameter adaptation maintains high system efficiency across different operating conditions.
3Stress or pressure
If excess hydraulic fluid is forced through a restriction to drive fluid through a pressure relief valve back to tank, then the pump can maintain pressure, but power is consumed and heat is added to the fluid
Solution Approach 1:
The harmful restriction and pressure relief valve pathway are extracted from the system design. Instead of forcing excess fluid through these restrictive elements, the system provides separate pump outputs that can be directly directed to actuators without needing to dump excess flow through restrictions, thereby eliminating the heat generation and power consumption associated with this wasteful process.
Solution Approach 2:
Rather than treating the excess pump output as a problem to be relieved through pressure valves, the system benefits from having a second pump that can utilize this capacity productively. The second pump's output can supply the second actuator, converting what would have been wasted energy into useful work, thereby eliminating heat generation from restriction-induced pressure relief.
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 configuration optimizes fluid flow to match the specific requirements of each actuator, reducing power consumption and heat generation, thereby enhancing the efficiency of the hydraulic system and the machine's performance.
Implementation Method 1
a first fixed displacement pump having a first pump output, and a second fixed displacement pump having a second pump output
Implementation Method 2
A combined flow control valve is controllable between a first state and a second state. When the combined flow control valve is disposed in the first state, the combined flow control valve is configured to separate the first pump output and the second pump output
Data Source
AI summary
A hydraulic system includes a first fixed displacement pump having a first pump output and a second fixed displacement pump having a second pump output. A first actuator requires a first required flow rate to perform a first function. A second actuator requires a second required flow rate to perform a second function. A combined flow control valve is controllable between a first state connecting fluid communication between the first fixed displacement pump and the tank so that only the second pump output is directed to the second actuator, and a second state disconnecting fluid communication between the first fixed displacement pump and the tank to combine the first pump output and the second pump output such that the combined first pump output and the second pump output is directed to the first actuator.