Hydraulic Pump Pressure Control for Stable Excavator Jack-Up
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Solution Overview
Problem
Conventional hydraulic excavators face issues with sudden pressure rises during boom lowering motions, affecting operability and flow rate control, and struggle to maintain adequate lifting force due to varying vehicle body weights, especially in heavier machines, leading to suboptimal jack-up operations.
Innovation Solution
The implementation of a construction machine with a body weight acquisition device, manipulated variable detector, delivery pressure detector, and a controller that adjusts the center bypass selector valve to maintain target delivery pressures, ensuring stable hydraulic pump operation and enhanced jack-up performance regardless of vehicle body weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the center bypass oil passage is fully closed to provide a powerful boom lowering motion, then the jack-up operation force is improved, but the delivery pressure of the hydraulic pump suddenly rises causing pressure oil to gush which impairs operability and flow rate control
Solution Approach 1:
The patent applies dynamics by making the bypass oil passage dynamically adjustable rather than fully closed. The control valve dynamically regulates the bypass flow based on pump delivery pressure, allowing the system to transition between high-force mode (when pressure is adequate) and pressure-control mode (when pressure rises excessively), thereby maintaining both jack-up force and operability
Solution Approach 2:
The patent implements feedback control by using the pump delivery pressure as a feedback signal to control the bypass valve. When delivery pressure reaches a predetermined level, the control valve automatically opens the bypass passage to relieve excess pressure, preventing sudden pressure rises and maintaining stable operability while still providing sufficient jack-up force
2Force
If the delivery pressure of the hydraulic pump is increased to provide adequate lifting force for heavier vehicle bodies, then the jack-up capability is improved, but the speed variations of hydraulic actuators in combined operation increases
Solution Approach 1:
The system uses feedback control where pump delivery pressure is continuously monitored and fed back to the control valve. This maintains pressure within an optimal range that provides sufficient lifting force for heavy vehicles while preventing excessive pressure that would cause speed variations in hydraulic actuators during combined operations
Solution Approach 2:
The patent changes the pressure parameter dynamically by adjusting the bypass valve opening based on delivery pressure conditions. This allows the system to maintain pressure at levels sufficient for heavy vehicle lifting while avoiding pressure levels that would cause actuator speed variations, thus resolving the contradiction between force and speed control
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 ensures satisfactory operational performance during jack-up operations by controlling hydraulic pump delivery pressure and flow rate, reducing speed variations and maintaining consistent lifting capabilities across different vehicle body weights, thereby improving operability and reliability.
Implementation Method 1
a hydraulic pump that is driven by the engine and delivers the hydraulic oil in the hydraulic oil tank as pressure oil
Implementation Method 2
a center bypass selector valve that is installed midway through a center bypass duct and downstream of the directional control valve, the center bypass duct connecting the hydraulic pump to the hydraulic oil tank, the center bypass selector valve having valve-opening area characteristics capable of fully closing the center bypass duct
Data Source
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AI summary
A controller according to the present invention has: a storage section that stores a first relationship between manipulated variables of an operating lever preset for each vehicle-body weight and target delivery pressures of a hydraulic pump; a target delivery pressure computation section that applies the vehicle-body weight inputted through an input device and the manipulated variable of the operating lever corresponding to a pilot pressure detected by pilot pressure sensors, to a first relationship stored in the storage section in order to calculate a target delivery pressure of the hydraulic pump; and a feedback control section that performs feedback control on the center bypass selector valve such that the delivery pressure of the hydraulic pump detected by the delivery pressure sensor agrees with the target delivery pressure of the hydraulic pump calculated by the target delivery pressure computation section.