Dual Stage Piloted Force Reduction Valve for Feller Bunchers
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Solution Overview
Problem
Feller bunchers experience hydraulic cylinder failure due to rebound forces from tree cutting, which existing solutions attempt to address by increasing cylinder robustness, leading to inefficiencies and redesign requirements.
Innovation Solution
A pressurized fluid subassembly with a sequence valve that manages fluid communication between high and low pressure lines, using a variable bias to inhibit or allow fluid flow based on the active supply to a fluid driven actuator, and a control valve for repositionable flow control to handle rebound forces without complete system redesign.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If larger, more robust hydraulic cylinders are incorporated to withstand rebound forces, then the reliability of the hydraulic system is improved, but the device complexity and weight increase, and the hydraulic pump and hoses must also be made more robust
Solution Approach 1:
The hydraulic system is segmented into two distinct circuits: a high-pressure circuit for normal operation and a low-pressure circuit for absorbing rebound forces. The sequence valve acts as a gateway between these circuits, allowing the system to handle rebound forces without requiring the entire hydraulic system to be robustly designed for such conditions.
Solution Approach 2:
A sequence valve is introduced as an intermediary component between the high-pressure and low-pressure circuits. This valve mediates the transfer of fluid based on pressure conditions, enabling the low-pressure circuit to absorb rebound forces while the high-pressure circuit maintains normal operational efficiency.
2Strength
If larger, more robust hydraulic cylinders are used to account for rebound forces, then the strength of the hydraulic system is improved, but additional weight is added to the feller head and boom
Solution Approach 1:
The hydraulic system is divided into high-pressure and low-pressure circuits, allowing the low-pressure circuit to handle rebound forces with lighter components. This segmentation enables the feller head and boom to be designed for operational strength rather than rebound resistance, reducing overall weight.
Solution Approach 2:
The function of absorbing rebound forces is extracted from the main hydraulic cylinders and assigned to a separate low-pressure circuit. This allows the primary hydraulic components to be optimized for their main function without the burden of withstanding rebound forces, thereby reducing weight.
3Reliability
If more robust hydraulic components are incorporated to withstand rebound forces, then the durability of the hydraulic system is improved, but the hydraulic pump and hoses must be redesigned to be less efficient
Solution Approach 1:
The hydraulic system is segmented into high-pressure and low-pressure circuits with distinct functions. The high-pressure circuit maintains efficiency for normal operations, while the low-pressure circuit handles rebound forces, allowing each circuit to be optimized independently without compromising overall system efficiency.
Solution Approach 2:
The sequence valve serves as an intermediary that directs fluid flow based on pressure conditions. During normal operation, it maintains the high-pressure circuit's efficiency, while during rebound events, it redirects fluid to the low-pressure circuit, protecting the system without reducing operational efficiency.
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 solution effectively mitigates rebound forces without requiring extensive redesign of the hydraulic system or equipment, enhancing efficiency and durability by managing pressure dynamics within the hydraulic system.
Implementation Method 1
a sequence valve interposing a low pressure line and a supply line conveying the fluid to the fluid driven actuator, the sequence valve including a first sequence configured to inhibit fluid communication between the supply line and the lower pressure line when the fluid at the high pressure is actively supplied to the fluid driven actuator
Implementation Method 2
a fluid driven actuator configured to utilize a fluid at a high pressure to change an overall length of the fluid driven actuator
Data Source
AI summary
A pressurized fluid subassembly comprising: (a) a fluid driven actuator configured to utilize fluid at a high pressure to change an overall length of the fluid driven actuator; and, (b) a sequence valve interposing a low pressure line and a supply line conveying the fluid to the fluid driven actuator, the sequence valve including a first sequence configured to inhibit fluid communication between the supply line and the low pressure line when the fluid at the high pressure is actively supplied to the fluid driven actuator, the sequence valve including a second sequence configured to establish fluid communication between the supply line and the low pressure line when the fluid at the high pressure is not actively supplied to the fluid driven actuator, wherein the sequence valve includes a variable bias that changes depending upon whether the fluid at the high pressure is actively supplied to the fluid driven actuator.