Hydraulic Control Device Priority Valve Elimination
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Solution Overview
Problem
The existing hydraulic control systems for construction vehicles require a priority valve to manage oil flow between steering and work machine actuators, leading to increased component complexity, labor-intensive manufacturing, and difficulties in pipe layout due to differing spool diameters and flow rates, which affects the efficiency and availability of the hydraulic pump.
Innovation Solution
A hydraulic control device that eliminates the need for a priority valve by using a meter-in pressure compensator and a bleed-off pressure compensator to manage oil flow, allowing independent pipe layout and ensuring stable oil supply to both the steering and work machine actuators, with the hydraulic pump adjusting its ejection rate based on pressure differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a priority valve is integrated with the steering control valve or work machine control valve, then the number of components is reduced, but the device complexity increases due to different spool diameters requiring different processing devices
Solution Approach 1:
The patent extracts the priority valve function from the integrated control valve unit and implements it separately through a priority hole formed in the spool of the steering control valve. This allows the steering control valve and work machine control valve to be manufactured independently using the same processing equipment, eliminating the need for different spool diameters and reducing manufacturing complexity while maintaining component integration benefits
Solution Approach 2:
The spool of the steering control valve is designed to serve multiple functions: it acts as both the control spool for steering and as the priority valve for directing oil flow. The priority hole in the spool enables it to automatically prioritize steering oil supply without requiring a separate priority valve component, reducing the number of parts while maintaining manufacturability
2Loss of energy
If the spool of the priority valve is formed larger in diameter to reduce pressure loss, then pressure loss is reduced, but the device complexity increases due to requiring different spool diameters for steering and work machine control valves
Solution Approach 1:
The patent extracts the priority valve function from a separate component and integrates it into the spool of the steering control valve through a priority hole. This allows the use of a single spool diameter for both steering and work machine control valves, eliminating the need for different spool sizes while maintaining low pressure loss through proper hole sizing and positioning
Solution Approach 2:
The priority hole in the spool acts as an intermediary mechanism that directs oil flow preferentially to the steering control valve when needed. This intermediate structure enables priority flow control without requiring oversized spools or complex multi-diameter designs, achieving low pressure loss with a unified spool design
3Device complexity
If the priority valve is arranged separately, then the integration complexity is reduced, but the pipe layout difficulty increases due to high-pressure oil flow requirements
Solution Approach 1:
The patent merges the priority valve function with the steering control valve by forming a priority hole directly in the steering control valve spool. This integration eliminates the need for separate priority valve components and complex high-pressure pipe connections, simplifying both the device structure and pipe layout while maintaining priority flow control functionality
Solution Approach 2:
The priority hole in the spool serves as an internal intermediary that directs high-pressure oil flow without requiring external high-pressure piping. This internal flow path eliminates the need for complex external pipe layouts while maintaining the priority valve function, simplifying both integration and installation
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 simplifies pipe layout, reduces labor and component complexity, and ensures efficient, stable oil supply to both actuators, enhancing the hydraulic pump's availability and operational efficiency without the need for a priority valve.
Implementation Method 1
a meter-in pressure compensator configured to control a flow of the operating oil, supplied to the steering control valve, to maintain differential pressure between pressure of the operating oil at an upstream side of the steering control valve and pressure of the operating oil at a downstream side of the steering control valve at constant pressure
Implementation Method 2
a bleed-off pressure compensator configured to control the flow of the operating oil supplied to the actuator control valve, utilize the pressure of the operating oil at the downstream side of the steering control valve as first pilot pressure, and utilize the pressure of the operating oil ejected from the hydraulic pump as second pilot pressure that acts against the first pilot pressure
Implementation Method 3
Adopted as the hydraulic pump is a variable displacement hydraulic pump, and the hydraulic pump controls an ejection amount thereof in accordance with pressure generated at an upstream side of the restrictor
Data Source
AI summary
A hydraulic control device includes: a hydraulic pump connected in parallel to steering and boom cylinders; a steering control valve that controls the direction of operating oil flowing through the steering cylinders; a boom control valve that connects the hydraulic pump to a tank when the valve is at a neutral position and controls the direction of the oil flowing through the boom cylinders when the valve is at an offset position; a meter-in pressure compensator that increases flow rate of the oil flowing through a variable restrictor of the steering control valve in accordance with pressure in front of and behind the restrictor; and a bleed-off pressure compensator that decreases flow rate of the oil flowing through the boom control valve in accordance with the increase in pressure of the oil flowing through the steering cylinders to maintain the predetermined pressure of the oil in the steering control circuit.