Boom Cylinder Float Control for Hydraulic Energy Recovery

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Solution Overview

Problem

Existing hydraulic machines fail to recover energy from the boom actuator during floating operations, particularly when the working device is hanging in the air, leading to inefficiencies in fuel consumption.

Innovation Solution

A hydraulic machine that determines the position of the working device during a boom-down operation and deactivates the floating hydraulic circuit if the device is hanging in the air, allowing energy recovery through pressure differentials in the boom actuator chambers and utilizing a recovery unit to enhance power and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the floating hydraulic circuit is activated to enable the working device to move up and down along the ground surface, then the floating function is improved, but energy recovery from the boom actuator is lost when the working device is hanging in the air

Engineering Contradiction:
Improvefloating functionVSAvoidenergy recovery
Core Design Contradiction:
Ease of operationVSLoss of energy

Solution Approach 1:

The hydraulic circuit configuration is made dynamic by automatically switching between floating mode and energy recovery mode based on the working device's position. When the working device is hanging in the air, the system automatically deactivates the floating hydraulic circuit and activates the energy recovery circuit, eliminating the need for manual operator intervention and ensuring optimal energy management under varying operational conditions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system employs pressure sensors to detect the position of the working device and provides feedback to the control unit. Based on this feedback, the control unit automatically determines whether to activate the floating hydraulic circuit or the energy recovery circuit, enabling intelligent, condition-based control that optimizes both floating functionality and energy recovery efficiency.

Inventive Principle:
Principle #23Feedback

2Reliability

If the floating hydraulic circuit remains active during boom down operation with working device hanging in the air, then the floating function is maintained, but fuel efficiency deteriorates due to inability to recover energy

Engineering Contradiction:
Improvefloating function availabilityVSAvoidfuel efficiency
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system dynamically adjusts the hydraulic circuit configuration based on operational conditions. During boom down operations when the working device is hanging in the air, the system automatically switches from floating mode to energy recovery mode, ensuring that the most efficient circuit configuration is active for each specific operational scenario, thereby optimizing fuel efficiency without compromising floating function availability when needed.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

Pressure sensors continuously monitor the hydraulic system state and provide feedback to the control unit. The control unit processes this information to automatically determine the appropriate circuit configuration, switching between floating and energy recovery modes based on the detected position of the working device, thus maintaining reliability while improving fuel efficiency.

Inventive Principle:
Principle #23Feedback

3Loss of energy

If pressure sensors and control logic are added to determine working device position, then energy recovery capability is improved, but device complexity increases

Engineering Contradiction:
Improveenergy recovery capabilityVSAvoidcontrol system complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The system utilizes existing hydraulic pressure signals and simple pressure sensors to detect the position of the working device, leveraging the hydraulic system's own physical state for control information. This approach avoids complex mechanical position sensors or additional complex detection systems, achieving energy recovery control through relatively simple hydraulic-based sensing and control logic.

Inventive Principle:
Principle #29Pneumatics and hydraulics

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

Enhances fuel efficiency by recovering energy from the boom actuator, reducing the size and cost of components like the accumulator and motor, and increasing power output during boom-down operations.

Implementation Method 1

determines whether or not the working device is hanging in the air based on a pressure in a large chamber and a pressure in a small chamber

Methodology Applied
Scientific EffectPressure differential: Pressure Gradient

Data Source

PatentEP3951073B1Hydraulic machine
Publication Date: 2026.04.01 VOLVO CONSTRUCTION EQUIPMENT AB
  • EP3951073B1 patent drawingFigure 1
  • EP3951073B1 patent drawingFigure 2
  • EP3951073B1 patent drawingFigure 3

AI summary

A hydraulic machine comprises: a tank (101); a working device including a boom; a boom cylinder which operates the boom and has a large chamber (313a) and a small chamber (313b); a floating hydraulic circuit connected to the large chamber (313a), the small chamber (313b), and the tank (101) so as to perform a floating function which enables the large chamber (313a), the small chamber (313b), and the tank (101) to communicate with each other; and an operator input device for receiving, from a driver, a request for turning on or turning off the floating hydraulic circuit. In the case of a boom down operation for lowering the boom, it is determined whether the working device floats in the air, and when it is determined that the working device floats in the air, the floating hydraulic circuit can be turned off, even if the request for turning on the floating hydraulic circuit is input to the operator input device. In some embodiments, when a value (the pressure of the large chamber (313a) - the pressure of the small chamber (313b)/(a valid area to which the pressure of the large chamber (313a) is applied/a valid area to which the pressure of the small chamber (313b) is applied)) is greater than a preset value, it may be determined that the working device floats in the air. In some alternative embodiments, when the value of the pressure of the large chamber (313a) is greater than the preset value, it may be determined that the working device floats in the air.