Double-Loop Hydraulic Motor Control for Energy Recovery
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Solution Overview
Problem
Existing hydraulic systems face inefficiencies due to the need for large hydraulic motors and additional cooling systems to manage varying torque requirements and wasted energy during rotating, lifting, and traveling processes, with existing energy recovery methods being limited in applicability and effectiveness.
Innovation Solution
A double-loop control system with a single hydraulic motor, comprising a positive control loop and a negative control loop, an accumulator, and an oil tank, where the loops work independently and interchangeably to manage torque requirements and recover braking kinetic and potential energy, integrating energy recovery and driving functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a large hydraulic motor is selected to meet maximum torque requirements during starting and accelerating, then the torque requirement is satisfied, but the volume of the hydraulic motor and control system increases, resulting in lower working efficiency
Solution Approach 1:
The patent applies variable displacement technology to the hydraulic motor, allowing the displacement to be dynamically adjusted during operation. During starting and accelerating phases, the motor operates at maximum displacement to deliver high torque. During stable operation, the displacement is reduced to minimize volume and energy consumption. This dynamic adjustment resolves the contradiction by enabling the motor to provide maximum torque only when needed while maintaining a compact size.
2Ease of operation
If conventional hydraulic valve control mechanism is used, then the control function is achieved, but kinetic energy and potential energy are wasted through throttling effect, transforming into heat and causing system failure
Solution Approach 1:
The patent converts the harmful throttling effect into a beneficial energy recovery mechanism. During braking and deceleration, instead of dissipating kinetic energy as heat through valve throttling, the system uses the hydraulic motor as a generator to convert the kinetic energy into electrical energy stored in super-capacitors. During falling or downhill travel, potential energy is similarly converted to electrical energy. This transforms the harmful energy waste into useful energy storage, resolving the contradiction between control function and energy loss.
Solution Approach 2:
The patent implements a feedback control system where sensors detect the operating state (braking, accelerating, falling, downhill travel) and automatically control the hydraulic control commutate valves to change direction. When braking is detected, the system automatically redirects high-pressure oil to charge the accumulator. When accelerating, stored energy is automatically released to drive the mechanism. This feedback mechanism ensures optimal energy recovery while maintaining precise control function.
3Reliability
If additional cooling system is added to cool the oil, then the system failure probability is reduced, but the energy consumption increases
Solution Approach 1:
The patent eliminates the need for additional cooling systems by converting the harmful heat generation into useful energy storage. Instead of allowing kinetic and potential energy to be wasted as heat through throttling, the system captures this energy during braking and deceleration phases and stores it in super-capacitors and accumulators. This not only reduces or eliminates the need for cooling but also recovers energy that would otherwise be lost, simultaneously improving reliability and reducing energy consumption.
4Use of energy by moving object
If hybrid power excavator with motor/generator is used, then energy efficiency is improved and system size is reduced, but the cost increases and applicability is limited to hybrid power machines
Solution Approach 1:
The patent makes the hydraulic motor serve multiple functions: it acts as a motor during normal operation and as a generator during braking and deceleration. By integrating the energy recovery function into the existing hydraulic motor without adding separate motor/generator units, the system achieves the energy efficiency benefits of hybrid power systems while avoiding the increased cost and complexity. This multi-functional approach resolves the contradiction by providing universal applicability to conventional hydraulic systems.
Solution Approach 2:
The patent merges the energy recovery function with the existing hydraulic motor and control system. Instead of adding separate hybrid power components, the system integrates the generator function into the hydraulic motor itself and combines the control mechanisms into a unified system. This merging approach achieves energy efficiency improvements while minimizing additional cost and complexity, making the solution more universally applicable than separate hybrid power systems.
5Loss of energy
If accumulator-based energy recovery system is used, then braking energy is recovered, but the accumulator state affects operating speed characteristics and stored energy cannot be fully used
Solution Approach 1:
The patent implements feedback control where sensors detect the operating state and the system automatically adjusts the hydraulic control commutate valves based on real-time conditions. When braking energy is recovered, the feedback system monitors the accumulator state and automatically controls the valve timing and direction to optimize both energy recovery and operating speed characteristics. This feedback mechanism ensures that stored energy is fully utilized while maintaining proper speed characteristics during acceleration and operation.
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 system enables continuous control of operation mechanisms, recovers kinetic and potential energy, and improves energy efficiency by using the positive and negative control loops to adapt to different driving force needs, reducing system size and energy consumption while enhancing reliability.
Implementation Method 1
an accumulator and two pressure sensors are added
Implementation Method 2
the accumulator state will affect the operating speed characteristics during rotating, and the stored energy cannot be fully used
Implementation Method 3
a hydraulic motor mainly drives machines for rotating, lifting and traveling
Implementation Method 4
kinetic energy generated by rotating-braking or decelerating braking, potential energy generated during falling or traveling downhill are wasted by being transformed into heat of oil through a throttling effect of valves
Data Source
AI summary
A double-loop control system with a single hydraulic motor relates to a technical field of hydraulic transmission control, including a hydraulic motor (1), a positive control loop (2), a negative control loop (3), a hydraulic pump (4), an accumulator (5), and an oil tank, wherein the hydraulic motor (1) adopts a unique thrust structure with four inlet/outlet ports; the positive control loop (2) and the negative control loop (3) independently control the hydraulic motor (1), wherein the positive control loop (2) and the negative control loop (3) drive together or only one drives; or braking kinetic energy and potential energy of loads are stored in the accumulator (5) for energy recovery. The present invention uses only one hydraulic motor for satisfying different work conditions and different load driving requirements with advantages such as simple structure, high system reliability and high energy efficiency.