Fluid Pressure Return Circuit for Preventing Cylinder Retraction
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Solution Overview
Problem
In fluid pressure circuits, unintentional operation of cylinder devices can occur due to erroneous electric signals from malfunctioning controllers, leading to unintended retraction of the cylinder device.
Innovation Solution
A fluid pressure circuit is designed with a control valve in the return flow passage to prevent unintentional operation by closing the return flow passage when the cylinder device is extended and the operation lever is in a neutral position, even if the flow diversion valve malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the flow diversion valve is controlled by an electric signal from the controller, then the regenerative motor can be activated to generate electric energy, but the system becomes vulnerable to erroneous signals causing unintentional cylinder operation
Solution Approach 1:
A control valve is introduced as an intermediary component between the operating device and the flow diversion valve. The control valve receives pilot fluid from the operating device and uses it to control the flow diversion valve's spool position. This intermediary mechanism ensures that the flow diversion valve can only be activated when the operating device is in the retraction direction, blocking erroneous electric signals from causing unintentional operation while preserving regenerative energy recovery functionality
2Productivity
If the flow diversion valve switches to flow diversion position based on electric signal, then energy can be recovered from return oil, but unintentional retraction may occur due to signal malfunction
Solution Approach 1:
The control valve is configured to prevent activation of the flow diversion valve unless specific conditions are met (operating device in retraction direction). This preliminary protective action blocks harmful erroneous signals before they can cause unintentional cylinder retraction, while still allowing legitimate retraction operations to proceed with energy recovery
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
This configuration effectively suppresses unintentional retraction of the cylinder device by ensuring the return flow passage is closed during potential malfunctions, thereby maintaining controlled operation.
Implementation Method 1
a return flow passage through which the return fluid flows from the cylinder device to the regenerative drive source is provided with a control valve that opens the flow passage in response to the operation of the operating device
Implementation Method 2
in the flow diversion valve, the position of the spool is changed from the neutral position to a flow diversion position in response to an electric signal transmitted from a controller
Implementation Method 3
some of return oil discharged from the bottom chamber is supplied to the regenerative motor, so that a generator is driven to obtain electric energy
Implementation Method 4
the position of a spool can be changed to an extension position, a neutral position, or a retraction position by the pilot fluid controlled in response to the operation of the operation lever of the remote control valve
Data Source
AI summary
There is provided a fluid pressure circuit capable of preventing unintentional operation of a cylinder device. A return flow passage through which a return fluid flows from a cylinder device to a regenerative drive source is provided with a control valve that opens the flow passage in response to an operation of an operating device.