Hydraulic Arrangement Dynamic Series Parallel Switching

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Solution Overview

Problem

Hydraulically driven vehicles face challenges with both parallel and series connection types, where parallel connections require more flow and lose torque if one wheel slips, while series connections provide less torque and stop both motors if a wheel encounters an obstruction.

Innovation Solution

A hydraulic arrangement that can dynamically switch between series and parallel connections using a proportional valve, allowing for automatic adjustment based on pressure and flow rate, enabling the benefits of both circuit types to be exploited depending on operational needs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If parallel connection is used, then vehicle speed is improved, but torque is lost when one wheel slips

Engineering Contradiction:
Improvevehicle speedVSAvoidtorque delivery
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The hydraulic circuit dynamically switches between parallel and series connections based on operating conditions. A valve controls the connection type, allowing the system to adapt: parallel connection for high speed when wheels have good traction, series connection for high torque when wheel slip or obstructions occur. This dynamic reconfiguration resolves the contradiction by making the system's connection type variable rather than fixed.

Inventive Principle:
Principle #15Dynamics

2Force

If series connection is used, then torque is improved, but both motors stop if a wheel encounters obstruction

Engineering Contradiction:
Improvemotor torqueVSAvoidcontinuous operation
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The system dynamically switches from series to parallel connection when a wheel encounters an obstruction. The valve detects the blocking condition and reconfigures the hydraulic circuit to parallel mode, allowing the unaffected motors to continue operating while maintaining torque capability. This dynamic adaptation prevents complete system failure while preserving torque delivery.

Inventive Principle:
Principle #15Dynamics

3Quantity of substance

If parallel connection is used, then flow requirement increases, but torque distribution is improved

Engineering Contradiction:
Improvehydraulic flowVSAvoidtorque distribution
Core Design Contradiction:
Quantity of substanceVSForce

Solution Approach 1:

The hydraulic circuit dynamically adjusts its configuration to match torque distribution needs. When high torque distribution is required (e.g., during acceleration or low-speed operation), the system switches to parallel connection despite higher flow requirements. When flow is limited or speed is prioritized, the system operates in series mode. This dynamic switching optimizes the trade-off between flow consumption and torque distribution.

Inventive Principle:
Principle #15Dynamics

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 solution allows for improved torque distribution and vehicle speed management, maintaining traction and efficiency by automatically switching to series mode when needed and reducing slip, while maintaining high speeds in low torque conditions.

Implementation Method 1

the at least one valve is configured for changing a connection of the hydraulic machines between a series connection and a parallel connection

Methodology Applied
Scientific EffectHydraulic connection switching: Hydraulic Press

Data Source

PatentEP3524859B1Hydraulic arrangement, hydraulic system, and hydraulically drivable vehicle
Publication Date: 2020.09.09 ROBERT BOSCH GMBH
  • EP3524859B1 patent drawingFigure 1
  • EP3524859B1 patent drawingFigure 2

AI summary

A hydraulic arrangement comprises: a pressure source, two hydraulic machines, and a proportional valve, wherein the valve is configured for changing a connection of the machines between a series connection and a parallel connection. The valve may be a proportional valve.