Electro-hydraulic Drive System with Boost Flow Line
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Solution Overview
Problem
Conventional hydraulic systems for work machines, such as excavators, suffer from inefficiencies due to power losses from throttling and the need for constant fluid flow from pumps, regardless of the number of actuators in use, leading to high energy consumption and costs.
Innovation Solution
An electro-hydrostatic actuation system that uses bi-directional pumps driven by electric motors to control fluid flow in unbalanced hydraulic cylinder actuators, eliminating the need for a dedicated boost pump by utilizing existing pumps and motors to provide boost flow through a shared fluid line, optimizing fluid flow based on the actuators' requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional hydraulic pump provides constant fluid flow to actuators, then the actuators can operate reliably, but energy consumption increases and system efficiency decreases
Solution Approach 1:
The patent applies dynamics by making the pump's displacement variable rather than fixed. The controller adjusts the pump's displacement based on real-time demands from multiple actuators, allowing the system to adapt fluid flow output dynamically. This resolves the contradiction by enabling the pump to provide reliable flow when needed while consuming less energy when actuator demand is low.
Solution Approach 2:
The patent changes the parameter of pump displacement from constant to variable. By adjusting the displacement parameter based on actuator requirements, the system optimizes energy consumption while maintaining reliable actuator operation. The controller monitors actuator demands and adjusts pump displacement accordingly, preventing energy waste from constant flow provision.
2Reliability
If a dedicated boost pump is added to handle flow differences in unbalanced actuators, then actuator performance is maintained, but device complexity and cost increase
Solution Approach 1:
The patent applies universality by making the main hydraulic pump perform multiple functions: it serves as both the primary actuator drive pump and the boost pump for handling flow differences in unbalanced actuators. The controller intelligently directs pump output to different actuators as needed, eliminating the need for a dedicated boost pump while maintaining actuator performance and reducing system complexity.
Solution Approach 2:
The patent merges the function of a dedicated boost pump with the main hydraulic pump. Instead of having separate pumps for different functions, the system combines them into a single pump controlled by a controller that manages flow distribution to multiple actuators. This consolidation reduces device complexity while maintaining the ability to handle unbalanced actuator requirements.
3Ease of operation
If throttling valves are used to control fluid flow to actuators, then flow control is achieved, but power losses increase due to throttling
Solution Approach 1:
The patent replaces the mechanical throttling valve system with an electro-hydraulic control system. Instead of using mechanical valves that create throttling losses, the system uses a variable displacement pump controlled by electrical signals from a controller. This substitution eliminates throttling power losses while maintaining flow control capability through electronic regulation of pump displacement.
Solution Approach 2:
The patent changes the control mechanism from fixed throttling to variable displacement. Rather than using valves to restrict flow from a constant displacement pump, the system varies the pump's displacement parameter to match actuator demands. This parameter change eliminates the need for throttling and the associated power losses while maintaining ease of operation through electronic 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 configuration enhances the efficiency of hydraulic systems by reducing energy consumption, eliminating the need for a dedicated boost system, and minimizing costs, while maintaining effective actuator performance.
Implementation Method 1
a bi-directional pump driven by an electric motor in opposite rotational directions to provide fluid flow to a first chamber or a second chamber of the hydraulic cylinder actuator
Implementation Method 2
provide fluid flow to a first chamber or a second chamber of the hydraulic cylinder actuator to drive the piston
Implementation Method 3
hydraulic system comprises: (i) a hydraulic cylinder actuator comprising a cylinder and a piston slidably accommodated in the cylinder
Data Source
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AI summary
An example hydraulic system includes a hydraulic cylinder actuator comprising a cylinder and a piston, wherein the piston comprises a piston head and a rod extending from the piston head, wherein the piston head divides an internal space of the cylinder into a first chamber and a second chamber, and wherein the hydraulic cylinder actuator is unbalanced; a first pump driven by a first electric motor to provide fluid flow to the first chamber or the second chamber of the hydraulic cylinder actuator to drive the piston; a boost flow line; a hydraulic motor actuator; and a second pump driven by a second electric motor, wherein the second pump is fluidly coupled to the boost flow line to provide boost fluid flow to the hydraulic cylinder actuator.