Boom Control Valve Circuit for Smooth Float-to-Normal Lowering
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Solution Overview
Problem
Existing construction machines face issues with operability and discomfort during mode switching between normal and float working modes due to the use of multiple valves, leading to potential shocks and inconsistent lowering operations.
Innovation Solution
A construction machine with a boom control circuit that integrates a control valve capable of four-position switching, including a lowering-side operating position with first and second regions, and a control unit that manages hydraulic oil supply based on ground-contact detection, ensuring unified lowering control across modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a dedicated switching valve is provided for float work apart from the control valve, then float work can be enabled, but the number of valves increases and valve switching control is required which leads to complicatedness of operation
Solution Approach 1:
The patent merges the float work function into the existing control valve by adding a float operating position to the spool valve. This allows the control valve to serve dual purposes - controlling both normal work and float work - thereby eliminating the need for a dedicated switching valve and reducing operational complexity
Solution Approach 2:
The control valve is designed with multi-functionality to handle both normal working mode and float working mode. By incorporating a float operating position that connects the rod end oil chamber, head end oil chamber, and oil tank, the single control valve can perform multiple functions without requiring additional specialized valves
2Adaptability or versatility
If different valves are used for lowering control in normal work and float work, then float work can be performed, but the lowering control becomes inconsistent and operator discomfort occurs
Solution Approach 1:
The patent merges the lowering control function into a single unified control mechanism within the spool valve. The same control valve that manages normal work lowering also manages float work lowering through its float operating position, ensuring consistent lowering control across both working modes and eliminating operator discomfort from inconsistent control
3Adaptability or versatility
If mode switching is performed from normal working mode to float working mode during lowering operation with bucket in air, then float work can be enabled, but oil passage switching causes shock
Solution Approach 1:
The spool valve provides continuous positional adjustment capability with multiple operating positions including neutral, raising-side, lowering-side, and float positions. This dynamic design allows for smooth transitions between modes by gradually adjusting the spool position rather than abrupt switching, thereby preventing shock during mode changes
Solution Approach 2:
The control system anticipates mode switching requirements and uses the neutral position and gradual spool movement to cushion transitions. By providing a neutral position and allowing gradual movement between positions, the system prepares for mode changes in advance, preventing sudden oil passage switching and associated shock
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
Enhances operability by maintaining consistent lowering operations in both normal and float working modes, reduces operator discomfort, and achieves energy savings by managing hydraulic oil supply efficiently.
Implementation Method 1
a boom with a base end portion being supported on a machine body in a vertically swingable manner; a stick (arm) supported on a leading end portion of the boom in a longitudinally swingable manner
Implementation Method 2
a spool valve is generally used, which is capable of switching to three positions: a neutral position at which the extension and contraction of the boom cylinder is stopped
Implementation Method 3
the boom, the stick, and the work attachment are configured to operate by extending and contracting operation of respective corresponding cylinders
Data Source
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AI summary
To perform a work with the same operability under a dead weight of a front work equipment (4) in any of a float work and a normal work, when a bucket (7) descends in the air, and after contacting the ground, to perform a work with the operability being maintained as it is when performing the float work, and to perform a work while pressurised hydraulic fluid is supplied from a hydraulic pump (11) when performing the normal work. SOLUTION: A lowering control during a float working mode is performed in a valve passage state in a first region (Dl) at which the lowering control is performed under the dead weight of the front work equipment (4) without being supplied with hydraulic fluid from the hydraulic pump (11), regardless of whether or not the bucket (7) is in contact with the ground, and the lowering control during a normal working mode is performed in a valve passage state at the first region in a non-ground-contacting state and at a second region (D2) in which the hydraulic fluid can be supplied from the hydraulic pump (11) in a ground-contacting state.