Hydraulic Drive Circuit with Sub-Pump for Precision Control
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Solution Overview
Problem
Conventional hydraulic drive circuits face challenges in achieving high responsiveness, precision, and efficiency at a low cost, particularly in industrial and construction machine applications, where the use of high-performance servo valves and large-capacity inverter motors is costly and not easily compatible with varying loads.
Innovation Solution
A hydraulic drive circuit configuration that includes a main hydraulic pump, a first valve to branch and circulate pressured liquid to hydraulic actuators, a second valve to return liquid to a tank, and a sub-hydraulic pump to increase pressure and volume, integrated within a manifold for improved performance and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a valve control type servo system using high-performance servo valves is used, then responsiveness and precision are improved, but introduction cost and running cost increase significantly
Solution Approach 1:
The patent divides the hydraulic pump system into multiple independent pumps (first pump, second pump, third pump) that can operate independently or in combination. This segmentation allows the system to achieve high precision control through coordinated operation of multiple simpler components rather than relying on a single complex servo valve, thereby reducing overall system cost while maintaining precision performance.
Solution Approach 2:
The patent designs a multi-functional pump system where the same set of pumps can serve multiple functions: individual operation for basic control, combined operation for high precision control, and flexible configuration for different load conditions. This eliminates the need for separate specialized components for different control modes, reducing introduction cost while maintaining versatility and precision.
2Loss of energy
If a pump control type servo system is used, then energy efficiency is improved, but responsiveness equivalent to valve control type cannot be achieved
Solution Approach 1:
The patent implements dynamic control of multiple pumps where the system can flexibly switch between different operational modes: single pump operation for energy efficiency during normal conditions, and multi-pump coordinated operation for high responsiveness during demanding conditions. This dynamic adaptability allows the system to maintain energy efficiency while achieving high responsiveness when needed.
Solution Approach 2:
The patent ensures continuous useful action by designing the multi-pump system to maintain optimal operation across varying load conditions. The pumps can operate individually or in combination to continuously provide the required hydraulic flow and pressure, ensuring both energy efficiency during light loads and high responsiveness during heavy loads without interruption or performance degradation.
3Power
If a large-capacity inverter servo motor is used, then power output is improved, but cost increases significantly
Solution Approach 1:
The patent segments the power delivery function across multiple hydraulic pumps instead of using a single large-capacity motor. Each pump can be driven by a smaller, more cost-effective motor, and the pumps work together to deliver the total required power output. This segmentation reduces the cost of individual motor components while achieving the same overall power capability.
Solution Approach 2:
The patent uses multiple smaller pump-motor units that replicate the basic hydraulic function rather than relying on a single large motor. Each unit is a simplified copy of the basic hydraulic drive concept, and their combined output achieves the power levels that would otherwise require an expensive large-capacity inverter servo motor, thereby reducing introduction cost while maintaining power output.
4Stress or pressure
If multiple pumps are simply serially coupled, then pressure-increasing effect is obtained, but system complexity and cost increase
Solution Approach 1:
The patent segments the hydraulic pressure generation function across multiple independent pumps that can operate in parallel or series configurations. Instead of a single complex high-pressure pump, the system uses multiple simpler pumps working together, which reduces individual component complexity while achieving the required pressure levels through coordinated operation.
Solution Approach 2:
The patent designs the multi-pump system with multi-functionality, where the same pump configuration can operate in different modes (parallel for flow, series for pressure, or individual for precision control) depending on system requirements. This flexibility reduces overall system complexity by using the same components for multiple functions rather than requiring specialized components for each function.
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 enhances the responsiveness and precision of hydraulic actuator control while reducing costs and system size, allowing for efficient use in mobile industrial applications by distributing loads effectively across a single main flow line.
Implementation Method 1
uses the pressured liquid flowing in the branched flow line to increase a pressure and a volume of the pressured liquid supplied from the main flow line to the hydraulic actuator
Implementation Method 2
uses the pressured liquid flowing in the branched flow line to increase a pressure and a volume of the pressured liquid supplied from the main flow line to the hydraulic actuator
Implementation Method 3
a first valve arranged in a main flow line that branches the pressured liquid discharged from the main hydraulic pump in two directions
Implementation Method 4
a second valve to return to a tank the pressured liquid flowing from the main flow line into one of the liquid chambers of the hydraulic actuator and discharged from the other liquid chamber
Data Source
AI summary
A hydraulic drive circuit is provided that can achieve high responsiveness, high precision, and high efficiency at a low cost in a hydraulic drive system popularly used in an industrial machine such as a press machine, a construction machine, and the like.A hydraulic drive circuit 1 supplies pressured liquid discharged from a main hydraulic pump P to drive a hydraulic actuator 2, and includes a first valve 4 arranged in a main flow line 3 that circulates pressured liquid discharged from the main hydraulic pump P to the hydraulic actuator 2, a second valve 5 to return the pressured liquid flowing into one liquid chamber of the hydraulic actuator 2 and discharged from the other liquid chamber to a tank T, and a sub-hydraulic pump 7 that is arranged between the main hydraulic pump P and the drive direction control valve 4 and uses the pressured liquid flowing in a branched flow line 6 branched from the main flow line 3 to increase a pressure and a volume of the hydraulic liquid in the main flow line 3 by predetermined quantities, respectively.