Segmented Hydraulic Drive System for Tracked Vehicles

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Solution Overview

Problem

Existing drive systems for tracked vehicles rely on oversized hydraulic motors and pumps to handle maximum power requirements, leading to inefficiencies and higher power losses, as these components are often used beyond their necessary capacity, limiting speed and traction performance.

Innovation Solution

Implementing a drive system with multiple hydraulic circuits that can be independently controlled, allowing for the selective switching on and off of hydraulic motors and pumps based on current power, speed, and traction needs, with energy recuperation and distribution across the drivetrain.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If oversized hydraulic motors and pumps are used to handle maximum power requirements, then the vehicle can achieve maximum tractive force and speed, but the hydraulic motors and pumps operate inefficiently when full power is not required, leading to higher power losses

Engineering Contradiction:
Improvemaximum tractive forceVSAvoidpower losses
Core Design Contradiction:
PowerVSLoss of energy

Solution Approach 1:

The patent divides the single hydraulic circuit into two independent hydraulic circuits, each with its own hydraulic motors and pumps. This segmentation allows each circuit to be independently controlled and sized according to actual power requirements, rather than requiring one oversized circuit to handle maximum power in all conditions. The control unit can selectively activate one or both circuits based on the tractive force and speed demands, optimizing efficiency by avoiding the operation of oversized components at partial load.

Inventive Principle:
Principle #1Segmentation

2Speed

If hydraulic motors and pumps are designed for maximum power output, then the vehicle can achieve maximum speed and tractive force, but the components become larger and more complex, reducing operational efficiency

Engineering Contradiction:
Improvemaximum vehicle speedVSAvoidhydraulic system complexity
Core Design Contradiction:
SpeedVSDevice complexity

Solution Approach 1:

The patent implements a dynamic control system that continuously monitors the operating conditions (tractive force requirements, speed demands) and dynamically adjusts the configuration of the hydraulic system. The control unit can selectively activate one or both hydraulic circuits based on real-time demands, allowing the system to adapt its complexity to the actual operating conditions. This dynamic approach enables the use of smaller, more efficient components that can be combined or operated independently rather than requiring one large static system.

Inventive Principle:
Principle #15Dynamics

3Power

If a single hydraulic circuit is used to handle maximum power flow, then the system can provide sufficient power for maximum vehicle performance, but the hydraulic pumps are consistently oversized for distributed power conditions, increasing power losses

Engineering Contradiction:
Improvemaximum power flowVSAvoidpump power losses
Core Design Contradiction:
PowerVSLoss of energy

Solution Approach 1:

The patent segments the single hydraulic circuit into two independent circuits, each capable of handling a portion of the total power requirement. This allows the hydraulic pumps in each circuit to be sized for approximately half the maximum power flow rather than the full maximum, reducing their size and associated power losses during normal distributed operation. When maximum power is required, both circuits can operate simultaneously to provide the necessary total power flow.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent combines two smaller hydraulic circuits to achieve the capability of handling maximum power flow when needed. Each circuit operates independently with its own pumps sized for partial load conditions, but they can be merged in operation to provide the total power required for maximum vehicle performance. This combining approach allows the system to achieve maximum power capability without requiring each individual pump to be oversized.

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 approach optimizes efficiency by using smaller motors and pumps, reducing power losses and enhancing speed and traction capabilities, while allowing for flexible energy distribution and reuse during braking and steering.

Implementation Method 1

a drive motor (1) for propelling the tracked vehicle, having a primary drive shaft (2), which drives, via a pump distribution gearbox (2), at least two hydraulic circuits (16, 17), each with at least one hydraulic pump (3, 23) and at least one hydraulic drive motor (4, 5, 24, 25)

Methodology Applied
Scientific EffectHydraulic principle: Hydraulic Press

Implementation Method 2

each with at least one hydraulic pump (3, 23) and at least one hydraulic drive motor (4, 5, 24, 25), the outputs of which act independently on a summing gearbox (7, 27)

Methodology Applied
Scientific EffectHydraulic motor operation: Hydraulic Press

Implementation Method 3

with the possibility of selectively switching individual hydraulic motors and hydraulic pumps on or off depending on the current demand for power, speed and tractive force

Methodology Applied
Scientific EffectEnergy recuperation: Hydraulic Accumulator

Data Source

PatentEP3378736B1Drive system for tracked vehicles and tracked working machines and method for controlling a drive system for tracked vehicles and tracked working machines
Publication Date: 2020.04.29 REPAIRCRAFT PLC
  • EP3378736B1 patent drawingFigure 1
  • EP3378736B1 patent drawingFigure 2
  • EP3378736B1 patent drawingFigure 3

AI summary

Drive system for tracked vehicles and tracked working machines, consisting of at least one drive motor, at least one pump distribution gearbox operatively connected to the drive motor, and at least one continuously variable hydraulic circuit per side of the vehicle, wherein each hydraulic circuit consists of at least two hydraulic pumps and at least one hydraulic motor, wherein the hydraulic pumps are operatively connected to the pump distribution gearbox, and wherein either at least one hydraulic motor and/or at least one hydraulic pump can be switched on or off to improve efficiency.