Hydraulic Valve System for Timber Harvesting Gripper Positioning
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Solution Overview
Problem
Existing hydraulic devices for wooden harvesting face difficulties in precise positioning of the gripper and saw unit during cutting, leading to inefficient and imprecise handling of tree trunks due to pressure sequence dependencies and lack of connection to the hydraulic agent tank, which complicates clean positioning on the harvest.
Innovation Solution
Incorporation of a first hydraulic valve with a check valve, a second hydraulic valve, a third hydraulic valve, and additional valves for overload protection, allowing for controlled hydraulic agent flow to maintain the gripper and saw unit in a precise cutting position by blocking or allowing fluid flow based on operational states, ensuring the gripper and saw unit can be accurately positioned and operated without pressure sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the hydraulic line is disconnected from the hydraulic fluid tank when not in use, then the system maintains precise positioning of the gripper and saw unit, but the hydraulic system becomes more complex with additional valves and control mechanisms
Solution Approach 1:
The patent introduces a check valve as an intermediary component in the hydraulic line between the first hydraulic cylinder and the hydraulic fluid tank. This check valve automatically maintains pressure on one side while allowing free flow on the other side, serving as a passive mediator that enables precise positioning without requiring complex active control systems. The check valve blocks the hydraulic line to the tank when pressure is applied, preventing the cutting element from dropping due to gravity.
2Extent of automation
If pressure sequence controls are used to operate the hydraulic cylinder, then the system can automate the cutting process, but the positioning precision is reduced due to pressure dependencies
Solution Approach 1:
The patent segments the hydraulic control system into two independent parts: (1) a pressure-controlled sequence valve that handles automation of the cutting process, and (2) a check valve that maintains precise positioning by blocking the hydraulic line to the tank. This segmentation allows the automated cutting sequence to operate independently from the positioning mechanism, eliminating the trade-off between automation and precision.
3Speed
If the hydraulic cylinder is allowed to return to the tank freely, then the system responds faster to position changes, but the cutting element drops due to gravity when switching to unpowered position
Solution Approach 1:
The check valve creates a periodic action pattern in the hydraulic system: during active cutting operations, the valve opens to allow rapid fluid flow and fast response; during positioning phases, the valve closes to maintain pressure and prevent gravitational drop. This periodic opening and closing behavior enables the system to achieve both fast response speed and high positioning accuracy at different operational stages.
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 precise positioning and operation of the gripper and saw unit during harvesting by eliminating pressure sequence dependencies, ensuring the gripper and saw unit can be accurately positioned and held in place, enhancing operational efficiency and reducing the risk of overload.
Implementation Method 1
a first hydraulic valve with a check valve, a second hydraulic valve, a third hydraulic valve, and additional valves for overload protection, allowing for controlled hydraulic agent flow to maintain the gripper and saw unit in a precise cutting position by blocking or allowing fluid flow based on operational states
Implementation Method 2
a first hydraulic valve with a check valve... designed to close when the first hydraulic line is pressurized and to open when the second hydraulic line is pressurized
Data Source
Figure 1
Figure 2
Figure 3a~4b
AI summary
A device for harvesting timber with a felling unit (1) which comprises a gripper and saw unit and a tilting device (9), wherein the gripper and saw unit comprises gripper arms (4), actuable by a first hydraulic cylinder (5), and a cutting element (6) which can be pivoted out by a second hydraulic cylinder (8), and can be pivoted from a depositing position into a cutting position for the timber (2) with the aid of the tilting device (9) which is actuable by a third hydraulic cylinder (10), wherein the first hydraulic cylinder (5) is connected to a first hydraulic line (19a) for opening the gripper arms (4) and to a second hydraulic line (19b) for closing the gripper arms (5). It is proposed that the gripper and saw unit maintains its position by interaction of a first hydraulic valve (12), a second hydraulic valve (13) and a third hydraulic valve (14), even in the case of an absence of pressurization of the hydraulic lines (19a, 19b), and makes precise positioning on the timber (2) possible.