Hydraulic Pump Pressure Control for Stalled Actuators
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hydraulic systems in working machines, such as wheel loaders, experience energy loss due to the need to maintain high pump pressure across multiple functions, leading to heat energy loss when pressures differ, and unnecessary wear when no actuators are in operation.
Innovation Solution
A method that discriminates pressure requests from stalled actuators, adjusting pump pressure based on the load pressure of operational actuators with lower demands, and maintains a lower idle pressure when no actuators are in operation, reducing energy loss and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the pump maintains high pressure to satisfy the highest pressure demand among multiple actuators, then the highest pressure actuator can operate, but energy is lost due to pressure reduction through valves for lower pressure actuators
Solution Approach 1:
The hydraulic system is segmented into multiple independent pressure zones, each served by a dedicated pump. The first pump serves actuators requiring high pressure (first pressure zone), while the second pump serves actuators requiring lower pressure (second pressure zone). This segmentation eliminates the need for pressure reduction valves and associated energy losses.
Solution Approach 2:
The system changes the pressure parameter by providing different pressure levels from different pumps based on the specific needs of each actuator. Instead of maintaining a single high pressure level throughout the system, the pressure is adapted to match the requirements of each actuator group, eliminating unnecessary pressure drops.
2Reliability
If the pump maintains maximal pressure continuously, then all actuators can operate at full capacity, but unnecessary wear occurs on the hydraulic system when no actuators are in operation
Solution Approach 1:
The hydraulic system dynamically adjusts the operating pressure based on the actual needs of the actuators. The control unit monitors the operation status of each actuator and activates only the necessary pumps at the required pressure levels. When no actuators are in operation, both pumps are deactivated, eliminating unnecessary wear from continuous high-pressure maintenance.
Solution Approach 2:
The control unit automatically manages the hydraulic system by monitoring actuator status and activating/deactivating pumps as needed. The system serves itself by detecting when high pressure is actually required and when it can be reduced or eliminated, preventing unnecessary wear without manual intervention.
3Device complexity
If a single pump serves multiple working functions with different pressure demands, then the system structure is simplified, but energy efficiency deteriorates due to pressure mismatch
Solution Approach 1:
The hydraulic system is divided into separate pressure zones with dedicated pumps for each zone. High-pressure actuators are served by the first pump, while low-pressure actuators are served by the second pump. This segmentation improves energy efficiency by eliminating pressure mismatches, despite increasing the number of pumps.
Solution Approach 2:
Each pump is designed to serve multiple actuators within its pressure zone. The first pump serves all high-pressure actuators, and the second pump serves all low-pressure actuators. This multi-functionality approach balances system complexity with energy efficiency.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a method for controlling a hydraulic system (10) of a working machine (1). The hydraulic system comprises a hydraulic machine (13) for providing hydraulic fluid to one or more actuators (11, 12) of the working machine. The method comprises the steps of receiving a signal requesting a pump pressure from the hydraulic machine (13) based on the load pressure of a first actuator (11) of said one or more actuators which first actuator has the highest load pressure of said one or more actuators, discriminating the pressure request from the first actuator (11 ) provided that the first actuator is stalled due to overload or geometrical limitations, and controlling the hydraulic machine (13) to provide a pump pressure based on the load pressure of a second actuator (12) of said one or more actuators which second actuator is in operation and has the second highest load pressure of said one or more actuators, or, if no actuator in addition to the first actuator is present and in operation, controlling the hydraulic machine to provide a predetermined idle pump pressure.