Hydraulic Arrangement for Implement Lifting Mode Switching
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Solution Overview
Problem
Hydraulic lifting and lowering arrangements on agricultural machines face issues with mechanical and hydraulic friction, leading to hysteresis and difficulty in switching between single and double acting modes, especially when handling implements of varying weights, and require manual effort for retraction during maintenance, posing safety concerns.
Innovation Solution
A hydraulic arrangement using a 4/3 directional valve and a 4/4 directional control valve with a blocking valve, allowing easy switching between single and double acting modes, and incorporating a pressure control system with an accumulator to manage weight distribution and implement lifting/lowering, and a locking mechanism for safety during maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single acting hydraulic cylinder is used to lower the carrying arm under implement weight, then the cylinder can retract automatically, but the cylinder cannot be retracted when no implement is attached (maintenance mode)
Solution Approach 1:
The hydraulic system dynamically switches between single-acting and double-acting modes based on operational requirements. During normal operation, the system functions as single-acting for automatic retraction. During maintenance, it transitions to double-acting mode enabling manual retraction when no implement weight is available to drive the piston back.
Solution Approach 2:
The hydraulic cylinder is designed to perform multiple functions: in normal operation mode it acts as a single-acting cylinder for automatic lowering, and in maintenance mode it functions as a double-acting cylinder allowing manual retraction. This multi-functionality resolves the contradiction between automatic retraction capability and maintenance mode operability.
2Adaptability or versatility
If a double acting hydraulic cylinder is used to enable manual lowering during maintenance, then the cylinder can be retracted without implement weight, but manual effort is required and friction prevents easy retraction
Solution Approach 1:
The system uses hydraulic pressure applied through the hydraulic cylinder to overcome the high friction forces in the pivot points and mechanical connections. By pressurizing the hydraulic fluid, sufficient force is generated to retract the piston and lower the carrying arm during maintenance, eliminating the need for excessive manual pushing force.
3Reliability
If hydraulic friction is present in the lifting arrangement, then hysteresis occurs in the lifting/lowering cycle, but the friction cannot be eliminated due to mechanical connections
Solution Approach 1:
The hydraulic system provides feedback through the hydraulic fluid pressure and flow characteristics. The hydraulic cylinder responds to pressure changes and flow rate adjustments, allowing the control system to compensate for friction-induced hysteresis by adjusting the pressurization timing and magnitude, thereby maintaining reliable control despite energy losses.
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 and controlled lifting and lowering of both heavy and light implements, reduces manual effort, and ensures safety by locking the hydraulic cylinders during maintenance, effectively addressing friction-related issues and safety concerns.
Implementation Method 1
pressurisation of the cylinder extends the piston rod which raises a carrying arm and implement
Implementation Method 2
incorporating a pressure control system with an accumulator to manage weight distribution and implement lifting/lowering
Implementation Method 3
there is legislation stating that it must be possible to lock and hold the at least one hydraulic cylinder so that its movement does not caused injury
Data Source
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AI summary
A hydraulic arrangement for lifting and/or lowering at least one implement carrying arm on an agricultural machine. The arrangement comprises an inlet hydraulic line and an outlet hydraulic line connecting a fluid pump (18) and a fluid reservoir (26) respectively to a first valve means (12), said arrangement comprising at least one dual acting hydraulic cylinder (15) for lifting/and or lowering the implement carrying arm. The at least one cylinder is connected to the first valve means (12) allowing the cylinder (15) to be switched between a single acting mode wherein the arm can be lifted and a double acting mode wherein the arm can be lifted and lowered.