Multi-Capacity Hydraulic Cylinder for Variable Load Speed
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional fluid cylinders compromise both force and speed, requiring sizing for high load conditions and acceptable movement speed, leading to inefficient operation under varying load conditions, especially when excess fluid is bypassed during low demand.
Innovation Solution
A multi-capacity hydraulic cylinder with multiple interior chambers, allowing for variable force and speed operation by adjusting chamber pressurization based on load conditions, using a hollow cylinder with a piston rod and secondary rod to create additional chambers with different cross-sectional areas, enabling automatic switchover among chambers for optimal performance with a single input pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the cylinder cross-sectional area is increased to provide larger force under high load conditions, then the force capacity is improved, but the actuation speed decreases
Solution Approach 1:
The cylinder is divided into multiple chambers with different cross-sectional areas (first chamber, second chamber, third chamber). Each chamber can be independently pressurized to provide different force-speed combinations. The piston rod is segmented into hollow sections allowing fluid communication between chambers, enabling selective activation of chambers based on load conditions.
Solution Approach 2:
The system dynamically switches between different chamber configurations based on operational demands. During high load conditions, larger chambers are pressurized for force. During low load conditions, smaller chambers are pressurized for speed. This dynamic adaptation eliminates the need for a fixed cylinder size and optimizes performance across varying operating conditions.
2Speed
If the flow rate is increased to achieve maximum actuation speed in unloaded conditions, then the speed is improved, but energy efficiency deteriorates due to excess fluid being bypassed
Solution Approach 1:
Instead of always using the full cylinder capacity, the system applies partial action by selectively pressurizing only the necessary chamber volume based on load conditions. During unloaded operations, only the smaller third chamber is pressurized, providing adequate speed without the energy waste of pressurizing the entire cylinder volume. This eliminates the need for bypassing excess fluid.
3Force
If the cylinder is sized for high load conditions, then the force capacity is sufficient, but the movement speed becomes unacceptable under the same sizing
Solution Approach 1:
The single cylinder structure performs multiple functions by utilizing different chamber combinations. It can operate in high-force mode (pressurizing first and second chambers) for heavy loads, and high-speed mode (pressurizing third chamber) for light loads. This multi-functionality allows one cylinder to replace what would traditionally require multiple cylinders or a variable displacement system.
4Device complexity
If a fixed flow pump is used to provide constant flow, then the system is simple, but energy is wasted when excess oil is bypassed during low demand conditions
Solution Approach 1:
The multi-capacity cylinder itself provides the flow regulation function that would otherwise require a variable displacement pump or flow control valves. By selectively pressurizing different chamber volumes, the cylinder self-regulates its fluid consumption to match the actual work demand, eliminating energy waste without requiring complex pump control systems.
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
Enables efficient operation across a range of loads and speeds by automatically adjusting chamber pressurization, increasing speed when unloaded and force when loaded, while maintaining constant pressure and flow, reducing fuel consumption and cycle time in applications like excavators and mining shovels.
Implementation Method 1
By pumping pressurized hydraulic fluid such as oil into and out of the interior chamber, the piston is moved within the cylinder
Implementation Method 2
a secondary rod moveable within the hollow piston rod to define a third chamber in the hollow piston rod, where the third chamber has a cross-sectional area that is less than the cross-sectional area of the first chamber
Data Source
AI summary
A multi-capacity hydraulic cylinder includes a hollow cylinder closed by a cylinder head, an annular piston moveable within the hollow cylinder to divide the interior of hollow cylinder into a first chamber and a second chamber, a hollow piston rod coupled to the piston and aligned with an opening in the piston, and a secondary rod moveable within the hollow piston rod to define a third chamber in the hollow piston rod, where the third chamber has a cross-sectional area that is less than the cross-sectional area of the first chamber.