Attachment Hydraulic Flow Control With Unloading Valve Pressure Balance
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Solution Overview
Problem
Existing hydraulic excavator systems face inefficiencies in energy conservation due to unnecessary throttle pressure loss and increased load pressure when switching between high and low flow rates for different attachments, as they require fixed throttle pressure losses and backpressure generation.
Innovation Solution
A construction machine with an attachment flow rate regulation valve device featuring a closed center type flow control valve and an unloading valve that maintains differential pressure, allowing for adaptive flow rate control without a special throttle, enabling easy switching between flow rates and improving energy conservation by avoiding unnecessary pressure losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a throttle is installed in the hydraulic line to control flow rate, then the flow rate can be regulated, but unnecessary throttle pressure loss occurs and energy conservation performance deteriorates
Solution Approach 1:
The patent removes the throttle component from the hydraulic line entirely. Instead of using a throttle to control flow rate, the system uses a flow control valve that regulates flow without creating unnecessary pressure loss. The flow control valve is positioned to control flow rate while the unloading valve handles pressure management separately, extracting the flow control function from the pressure loss-generating throttle mechanism.
Solution Approach 2:
The patent introduces an unloading valve as an intermediary component between the hydraulic pump and the hydraulic line. This unloading valve maintains differential pressure across the flow control valve and prevents backpressure from propagating back to the pump, thereby protecting the system from energy loss while still enabling flow rate control.
2Adaptability or versatility
If a bypass valve is used to switch between high and low flow rates, then flow rate switching is enabled, but backpressure is generated and load pressure of the hydraulic pump increases
Solution Approach 1:
The patent segments the flow control function into two independent parts: a flow control valve for precise flow rate regulation and an unloading valve for pressure management. This segmentation allows the system to switch between high and low flow rates without generating backpressure, as each valve handles its specific function independently without interfering with the other.
Solution Approach 2:
The unloading valve serves as an intermediary that protects the hydraulic system from backpressure. It is positioned to maintain differential pressure across the flow control valve and unload excess pressure before it can affect the hydraulic pump, thereby enabling flow rate switching without increasing load pressure on the pump.
3Ease of operation
If fixed throttle pressure loss is required for flow control, then flow rate can be limited, but energy conservation performance is deteriorated
Solution Approach 1:
The patent extracts the flow control function from the throttle mechanism, eliminating the fixed throttle pressure loss. The flow control valve is designed to regulate flow rate based on actual system needs rather than imposing a fixed pressure drop, thereby maintaining energy conservation performance while still achieving flow rate control.
Solution Approach 2:
The patent implements dynamic flow control where the flow control valve adjusts flow rate based on real-time system conditions rather than maintaining a fixed throttle setting. The unloading valve dynamically maintains differential pressure across the flow control valve, allowing the system to adapt flow rates to actual work requirements and avoid unnecessary energy consumption.
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
The system allows for quick adaptation to different attachments by regulating the maximum flow rate efficiently, reducing energy consumption and maintaining energy conservation performance by eliminating unnecessary backpressure and throttle pressure loss.
Implementation Method 1
having, at an end portion of a side in which the unloading valve is actuated in a closing direction, a pressure receiving section to which a load pressure of the actuator is introduced and a spring, and having, at an end portion of a side in which the unloading valve is actuated in an opening direction, a pressure receiving section to which a pressure from the hydraulic line is introduced
Implementation Method 2
a flow control valve of a closed center type connected to the hydraulic line and configured to regulate a flow rate of the hydraulic fluid passing through the first selector valve
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A construction machine that can easily regulate a set maximum flow rate at a time of replacement of an attachment and that can improve an energy conservation performance is provided. A controller (71) selects a corresponding map in response to an attachment designation signal from among maps each of which sets a relationship between an operation signal per type of the attachment and a flow rate of a hydraulic fluid supplied to an actuator, generates a control signal by causing the selected map to refer to the operation signal, and controls a flow control valve (51) of an attachment flow rate regulation valve device (40) in such a manner that a position of the flow control valve is switched over from a neutral position on the basis of the control signal. An unloading valve (55) that maintains a differential pressure across the flow control valve (51) is disposed in the attachment flow rate regulation valve device (40).