Hydraulic Circuit Control for Prime Mover Speed Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Industrial vehicles with multiple hydraulically powered actuators face inefficiencies in energy usage, leading to suboptimal fuel efficiency and increased costs, due to the lag in response times between prime movers and hydraulic machines, which results in engine droop and potential stalling.
Innovation Solution
A hydraulic control system that includes electronically commutated machines (ECMs) with a prime mover speed governor, which regulates the prime mover speed through feedforward torque demand signals, allowing the hydraulic machine to adjust displacement and torque in sync with the prime mover, thereby optimizing energy use and preventing engine droop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the hydraulic machine responds quickly to torque demand, then the response time is improved, but the prime mover speed stability deteriorates due to engine droop
Solution Approach 1:
The system performs preliminary action by anticipating torque demand and adjusting the hydraulic machine displacement before the prime mover can respond. The controller receives torque demand signals and proactively modulates the hydraulic machine output to match the anticipated demand, preventing engine droop before it occurs. This is achieved through feedforward control where the hydraulic machine displacement is adjusted in advance based on predicted torque requirements.
Solution Approach 2:
The system implements feedback control by continuously monitoring prime mover speed and torque demand, then adjusting hydraulic machine displacement to maintain speed stability. The controller compares actual prime mover speed with target speed and modulates hydraulic machine output accordingly, creating a closed-loop control system that corrects speed deviations caused by engine droop.
2Power
If the prime mover torque is increased to meet hydraulic demand, then the power availability is improved, but the energy efficiency deteriorates due to unnecessary torque application
Solution Approach 1:
The system applies dynamics by continuously and dynamically adjusting hydraulic machine displacement to match actual torque demand in real-time. Rather than maintaining fixed or excessive torque capacity, the hydraulic machine displacement is modulated dynamically based on instantaneous torque requirements, ensuring power availability matches actual needs and improving energy efficiency.
Solution Approach 2:
The system implements parameter changes by varying the hydraulic machine displacement parameter in response to torque demand signals. The controller adjusts displacement parameters to optimize the balance between power availability and energy efficiency, changing operational parameters dynamically rather than maintaining fixed settings.
3Quantity of substance
If the hydraulic machine displacement is increased to meet actuator demand, then the hydraulic flow availability is improved, but the prime mover load increases causing speed droop
Solution Approach 1:
The system performs preliminary action by anticipating hydraulic flow demand and adjusting hydraulic machine displacement before the prime mover speed can droop. The controller receives torque demand signals and proactively modulates hydraulic machine output to match anticipated demand, preventing excessive prime mover loading and speed instability before they occur.
Solution Approach 2:
The system implements feedback control by continuously monitoring prime mover speed and hydraulic demand, then adjusting hydraulic machine displacement to maintain speed stability while meeting flow requirements. The controller compares actual speed with target speed and modulates hydraulic machine displacement accordingly, creating a closed-loop that prevents speed droop.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A prime mover (22) and a plurality of hydraulic actuators (6), a hydraulic machine (32) having a rotatable shaft in driven engagement with the prime mover and comprising a plurality of working chambers, a hydraulic circuit extending between a group of one or more working chambers of the hydraulic machine and one or more of the hydraulic actuators, each working chamber of the hydraulic machine comprising a low-pressure valve (52) which regulates the flow of hydraulic fluid between the working chamber and a low-pressure manifold and a high-pressure valve (64) which regulates the flow of hydraulic fluid between the working chamber and a high-pressure manifold. The hydraulic machine being configured to actively control at least the low-pressure valves of the group of one or more working chambers to select the net displacement of hydraulic fluid by each working chamber on each cycle of working chamber volume, and thereby the net displacement of hydraulic fluid by the group of one or more working chambers, responsive to a demand signal, wherein the apparatus further comprises a controller (26) configured to calculate the demand signal in response to a measured property of the hydraulic circuit or one or more actuators.