Manifold Valve Pressure Control for Hydraulic Response Delay
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Solution Overview
Problem
Materials handling vehicles experience delays in operating auxiliary devices like reach, side-shift, and tilt mechanisms due to the large volume of oil required for fluid pressure, which causes a delay in responding to operator commands as counterbalance valves only close after pressure falls below a threshold, leading to continued movement after a stop command is initiated.
Innovation Solution
The implementation of an electronically controlled proportional pressure reducing and relieving valve in the fluid supply system, coupled with an electronic controller, maintains fluid pressure at the output port equal to or greater than the required operating pressure of the auxiliary devices, ensuring timely operation and reducing delays by modulating flow to match operator commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure controlled counterbalance valves are used to lock pistons in place, then reliability of piston positioning is improved, but loss of time increases because the valves only close after pressure falls below threshold
Solution Approach 1:
The system pre-fills the supply line with pressurized oil and maintains it under pressure in readiness, so that when an operator command is given, the oil is already positioned and pressurized, eliminating the delay caused by filling and pressurizing the line after the command is given
2Stress or pressure
If a large volume of oil is supplied to fill the supply line between manifolds, then sufficient fluid pressure is achieved for auxiliary device operation, but loss of time increases due to the delay in filling and pressurizing the line
Solution Approach 1:
The supply line is pre-filled with oil and pre-pressurized before the operator command is given, so that when the command is received, the oil is already in position and at the required pressure, eliminating the time delay associated with filling and pressurizing the line after command initiation
3Stability of the object's composition
If counterbalance valves maintain back pressure in cylinders, then smooth piston motion is achieved, but loss of time increases because movement continues after stop command until pressure falls below threshold
Solution Approach 1:
The system uses feedback from the operator's command to immediately modulate the flow control valve and close the check valve, providing real-time control that stops piston movement immediately when a stop command is given, eliminating the delay caused by waiting for pressure to naturally fall below the counterbalance valve threshold
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 solution reduces the delay in initiating or stopping auxiliary device operations by maintaining the necessary fluid pressure, allowing for quicker response to operator commands and improved control over the movement of the fork carriage mechanism, enhancing the overall efficiency and precision of the materials handling vehicle.
Implementation Method 1
pump structure for supplying a fluid
Implementation Method 2
valve structure for maintaining fluid pressure at an output port of the first manifold apparatus at a commanded pressure substantially equal to or greater than an operating pressure of the first auxiliary device
Implementation Method 3
the flow rate varies based on the selected auxiliary device and the magnitude of the operator input command
Data Source
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AI summary
A materials handling vehicle is provided comprising: a power unit; a work assembly coupled to the power unit comprising a first auxiliary device; and a fluid supply system. The fluid supply system may comprise: pump structure for supplying a fluid; a first manifold apparatus located on the power unit; a second manifold apparatus located on the work assembly; and fluid supply line structure coupled between the first and second manifolds. The first manifold may receive fluid from the pump structure and comprise valve structure for maintaining fluid pressure at an output port of the first manifold apparatus at a commanded pressure substantially equal to or greater than an operating pressure of the first auxiliary device.