Variable Displacement Hydraulic Pump Flow Control
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Solution Overview
Problem
Hydraulic systems in agricultural and construction machines face inefficiencies at low engine rotational speeds, leading to insufficient volume flow and high power losses at high speeds, due to the limitations of existing adjustable displacement pumps, which result in increased fuel consumption and costly component designs.
Innovation Solution
A hydraulic system with a flow control member coupled to a piston, controlled by an electronic unit that adjusts the maximum flow rate based on engine speed, allowing for high flow rates at low speeds and limiting them at high speeds, using a stop mechanism and adjusting devices such as a stepper motor to optimize flow rates and reduce power losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pump is designed for high flow rates at low engine speeds, then sufficient volume flow is achieved at low speeds, but power losses increase at high speeds
Solution Approach 1:
The pump's maximum flow rate is made dynamically adjustable through an electronic control system that modifies the pump's displacement or flow characteristics based on real-time engine speed feedback. This allows the system to adapt the pump's flow capacity to match actual operational requirements, preventing excessive flow rates at high engine speeds while ensuring sufficient flow at low speeds.
Solution Approach 2:
The system changes the operational parameters of the pump by electronically adjusting the maximum flow rate setting based on engine speed conditions. The control unit receives engine speed signals and accordingly modifies the pump's flow parameters, transitioning from a fixed flow rate design to a variable flow rate system that optimizes performance across different operating conditions.
2Productivity
If the pump is designed for high flow rates to meet maximum demand, then sufficient flow is available at all speeds, but fuel consumption increases due to continuous high power output
Solution Approach 1:
The pump system transitions from a static high-flow design to a dynamic flow control system that continuously adapts the flow rate to actual hydraulic consumer demands and engine speed conditions. This dynamic adjustment ensures that the pump only delivers the necessary flow volume, avoiding continuous operation at maximum capacity and thereby reducing fuel consumption while maintaining productivity.
Solution Approach 2:
The control unit receives feedback signals from engine speed sensors and hydraulic consumer demand indicators to continuously adjust the pump's flow rate. This closed-loop feedback system ensures that the pump operates at the optimal flow rate for current conditions, preventing energy waste from excessive flow while ensuring sufficient flow availability when needed.
3Device complexity
If fixed displacement pumps with rigid gearboxes are used, then simple mechanical connection is achieved, but flow rate cannot be adjusted to match consumer demand
Solution Approach 1:
The system replaces traditional mechanical flow control mechanisms (such as rigid gearboxes with fixed ratios or mechanical flow control valves) with an electronic control system. This substitution maintains the simplicity of the mechanical pump connection while adding electronic intelligence that enables flexible flow rate adjustment based on operational conditions, thereby achieving both simplicity and adaptability.
Solution Approach 2:
The pump system transitions from a fixed mechanical flow rate determination to a dynamic electronic control system that can continuously adjust the flow rate. This allows the system to maintain simple mechanical connections while achieving versatile flow rate adaptability through electronic modulation of the pump's displacement or flow characteristics.
4Productivity
If valves with larger cross sections are used to compensate for pressure losses, then volume flow is improved, but system complexity and cost increase
Solution Approach 1:
Instead of using larger valve cross sections to compensate for pressure losses (which would increase system complexity), the system converts the potential harm of pressure losses into a benefit by electronically adjusting the pump's flow rate to match actual consumer demands. This prevents excessive flow rates that would cause unnecessary pressure losses in the first place, thereby maintaining efficient flow through existing valve configurations without requiring larger or more complex valve designs.
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 ensures high flow rates at low engine speeds while preventing excessive flow at high speeds, reducing power losses and allowing for efficient operation across varying conditions, including temperature adjustments, thereby optimizing power usage and maintaining system availability despite potential electronic failures.
Implementation Method 1
adjusting devices such as a stepper motor to optimize flow rates
Implementation Method 2
an engine driven adjustable or variable displacement hydraulic pump which supplies hydraulic fluid to a hydraulic consumer
Implementation Method 3
The flow rate controller of an LS controlled pump operates so that it controls the flow rate of the pump
Data Source
AI summary
A hydraulic system includes an engine driven variable displacement hydraulic pump which supplies fluid to a hydraulic consumer and an electronic control unit. A flow rate adjusting unit includes a stop that can be brought into engagement with an adjusting piston. In order conform the power output of the pump to the operating conditions of the vehicle, the stop of the flow rate adjusting unit includes adjusting devices that can be controlled by the control unit, so that the maximum flow rate of the pump can be varied by the electronic control unit. The electronic control unit generates a control signal for the adjusting device as a function of a sensed engine speed.