Electro-Hydraulic Cylinder Network With Valve-Free Short-Circuit Flow

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Solution Overview

Problem

Existing electro-hydraulic drive networks suffer from low energy efficiency due to the use of valves, which lead to inherent losses and affect performance and reliability.

Innovation Solution

The electro-hydraulic drive network employs differential hydraulic cylinders with short-circuit connections between chambers, reducing the need for valves by using displacement units controlled by electric machines, and optionally incorporating parallel connections of hydraulic cylinders for enhanced stability and force output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If valves are used to regulate fluid flow in the electro-hydraulic drive network, then control capability is improved, but energy efficiency deteriorates due to inherent losses

Engineering Contradiction:
Improvecontrol capabilityVSAvoidenergy efficiency
Core Design Contradiction:
Ease of operationVSLoss of energy

Solution Approach 1:

The patent removes valves from the hydraulic circuit by implementing direct fluidic connections between cylinder chambers. The short-circuit connections allow fluid to flow directly between chambers without passing through valve components, thereby eliminating the energy losses associated with valve regulation while maintaining control capability through direct displacement unit control.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces short-circuit connections as intermediary fluid pathways between cylinder chambers. These direct connections serve as mediators that enable controlled fluid transfer without requiring traditional valve intermediaries, thus achieving both control capability and energy efficiency.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If valves are used in the electro-hydraulic drive network, then flow regulation is improved, but reliability deteriorates due to valve-related problems

Engineering Contradiction:
Improveflow regulationVSAvoidsystem reliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent extracts valves from the system entirely, replacing them with direct fluidic short-circuit connections. This elimination of valve components removes the source of valve-related reliability problems while maintaining flow regulation capability through the displacement units that directly control fluid movement between chambers.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The system uses self-contained short-circuit connections that require no external control mechanisms. The direct fluid pathways enable the hydraulic system to regulate flow inherently through its own structure, eliminating dependence on external valve components that could fail.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If traditional hydraulic circuits with valves are used, then control precision is achieved, but device complexity increases

Engineering Contradiction:
Improvecontrol precisionVSAvoidcircuit complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent removes the complex valve infrastructure from traditional hydraulic circuits, replacing it with simplified short-circuit connections between chambers. This reduction in components directly lowers device complexity while maintaining control precision through the direct control pathway from displacement units to cylinder chambers.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the functions of multiple valve-controlled circuits into integrated short-circuit connections. By combining fluid pathways directly between chambers, the system achieves control precision with a unified, less complex structure rather than multiple separate valve-controlled channels.

Inventive Principle:
Principle #5Merging (Combining)

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 achieves near-loss-free fluid flow and reduces susceptibility to valve-related issues, enhancing energy efficiency, stability, and control precision in mechanical operations.

Implementation Method 1

hydraulic fluid serves as the medium for energy transmission, with pumps generating flow and pressure

Methodology Applied
Scientific EffectHydraulic pressure transmission: Hydraulic Press

Implementation Method 2

The short-circuit connections may be realized directly between the appropriate cylinder chambers or via a manifold or similar and enables unobstructed (near loss-free) fluid flow between the given control volumes entailing nearly identical pressures in the short-circuited cylinder chambers.

Methodology Applied
Scientific EffectFluid short-circuiting:

Implementation Method 3

displacement units for controlling the first, second, third and fourth volumes

Methodology Applied
Scientific EffectHydraulic displacement: Pump

Implementation Method 4

each of the electric machines is controlled by an electric drive

Methodology Applied
Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Data Source

PatentEP4621248A1Electro-hydraulic drive network and excavator comprising a hydraulic drive
Publication Date: 2025.09.24 ROBERT BOSCH GMBH
  • EP4621248A1 patent drawingFigure 1
  • EP4621248A1 patent drawing
  • EP4621248A1 patent drawing

AI summary

The invention relates to an electro-hydraulic drive network (10) comprising a first hydraulic cylinder (12), a second hydraulic cylinder (14) and a third hydraulic cylinder (16), wherein each hydraulic cylinder (12, 14, 16) having a first chamber (42, 50, 52) and a second chamber (44), wherein the first chamber (42) of the first hydraulic cylinder (12) is fluidly connected to the second chamber (44) of the second hydraulic cylinder (14) forming a first volume (40), wherein the second chamber of the first hydraulic cylinder (12) forms a second volume (46), wherein the first chamber (50) of the second hydraulic cylinder (14) is fluidly connected to the first chamber (52) of the third hydraulic cylinder (16) forming a third volume (48), wherein the second chamber of the third hydraulic cylinder (16) forms a fourth volume (54), wherein the electro-hydraulic drive network (10) further comprises displacement units (18, 20, 22, 24).