Hydraulic Suspension Damping via Flow Division

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Solution Overview

Problem

Conventional cab suspension systems require complex control technology and expensive sensor systems to achieve uniform damping, leading to power losses, component overloading, and high maintenance costs, while also failing to minimize unwanted inclinations during cornering.

Innovation Solution

A suspension system with a partial fluid flow division during compression, where one partial flow is fed back into a hydraulic cylinder's rod space, reducing power losses and component loading, and using a proportional throttle valve for adjustable damping, along with non-return valves and cross-connected hydraulic cylinders to ensure identical damping and improved roll stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the entire fluid flow from the piston chamber flows through the throttle valve during compression, then damping is achieved, but power losses and heating of the hydraulic fluid increase significantly

Engineering Contradiction:
Improvepower lossesVSAvoiddamping control complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The fluid flow from the piston chamber is divided into two separate partial flows: one flows directly to the rod chamber without passing through the throttle valve, while the other flows through the throttle valve to the hydraulic accumulator. This segmentation reduces the throttling loss by eliminating the need to throttle the entire fluid flow, thereby reducing power losses and heating while maintaining damping control through the throttled portion.

Inventive Principle:
Principle #1Segmentation

2Reliability

If two throttles are used with opening cross-sections corresponding to the piston to rod area ratio, then uniform damping during compression and rebound is achieved, but the system becomes complex and requires great effort to dimension the throttles

Engineering Contradiction:
Improveuniform dampingVSAvoidthrottle valve complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The direct connection between the piston chamber and rod chamber is extracted from the system, creating a separate bypass path that does not go through the throttle valve. This allows the throttle valve to only handle the portion of fluid flow that requires damping control, simplifying the valve design and dimensioning while maintaining uniform damping characteristics through the proportional relationship between the direct flow and throttled flow.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If a complex sensor system and control technology are used to ensure uniform damping, then damping uniformity is improved, but the system cost and component loading increase

Engineering Contradiction:
Improvedamping uniformityVSAvoidsystem cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The hydraulic system itself provides the damping control function through the proportional division of fluid flow. The branch connection automatically divides the fluid flow into two partial flows, with one portion being throttled to the accumulator and the other flowing directly to the rod chamber. This self-regulating mechanism achieves uniform damping without requiring external sensors or complex electronic control systems, thereby reducing system cost and component loading.

Inventive Principle:
Principle #25Self-service

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

The system achieves defined and adjustable damping with reduced power losses and component loading, minimizing unwanted inclinations and allowing for cost-effective, reliable, and compact construction with fewer components, ensuring precise control and reduced susceptibility to faults.

Implementation Method 1

the hydraulic cylinder being connected to at least one hydraulic accumulator for compression and rebound

Methodology Applied
Scientific EffectHydraulic accumulator: Hydraulic Accumulator

Implementation Method 2

a branch for dividing a fluid flow from the piston chamber during compression into a partial flow that flows to a rod chamber of a hydraulic cylinder and a partial flow that flows through a throttle valve to a hydraulic accumulator

Methodology Applied
Scientific EffectThrottling: Pressure Drop

Data Source

PatentEP3381721B1Suspension system
Publication Date: 2020.12.09 DEERE & CO
  • EP3381721B1 patent drawingFigure 1
  • EP3381721B1 patent drawingFigure 2
  • EP3381721B1 patent drawingFigure 3

AI summary

The invention relates to a suspension system, in particular a cabin suspension with at least one hydraulic cylinder (3). The hydraulic cylinder (3) has a piston chamber (12) and a rod chamber (11). The hydraulic cylinder (3) is connected to at least one hydraulic accumulator (4) for compression and rebound. The suspension system has a branch (15) for splitting a fluid flow (13). During compression, the fluid flow (13) from the piston chamber (12) splits into a partial flow (16) that flows to a rod chamber (11) and a partial flow (17) that flows through a throttle valve (19) to a hydraulic accumulator (4).