Hydraulic Linear Drive with Three Pressure Chambers

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Solution Overview

Problem

Existing hydraulic linear drives require complex and costly device technology, including variable displacement pumps and additional charging pumps, to manage both rapid traverse and power stroke operations efficiently.

Innovation Solution

A hydraulic linear drive design featuring a hydraulic cylinder with three pressure chambers, where the surface ratios of the effective surfaces are coordinated to operate in the same speed range for both rapid traverse and power stroke, utilizing a speed-variable drive and a valve arrangement to minimize energy expenditure and investment costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a variable displacement pump and additional charging pump are used to control rapid traverse and power stroke, then the hydraulic linear drive can operate efficiently in both modes, but the device complexity and investment costs increase significantly

Engineering Contradiction:
Improveoperational efficiency in rapid traverse and power strokeVSAvoidcomplexity of pump system and valve arrangement
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent combines the functions of the variable displacement pump and charging pump into a single constant delivery pump. The pump system is merged with a valve arrangement that uses a variable delivery volume to control hydraulic fluid distribution to the three pressure chambers, eliminating the need for separate pumps while maintaining efficient operation in both rapid traverse and power stroke modes

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The constant delivery pump is designed to perform multiple functions: it supplies hydraulic fluid for both rapid traverse and power stroke operations, and works in conjunction with the valve arrangement to regulate flow distribution to different pressure chambers. This multi-functional design replaces what would traditionally require separate specialized pumps

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Ease of operation

If a variable displacement pump is used to control hydraulic cylinder movements, then rapid traverse and power stroke can be controlled, but the control system complexity and investment costs increase

Engineering Contradiction:
Improvecontrol of rapid traverse and power strokeVSAvoidcomplexity of control system
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent introduces a valve arrangement as an intermediary between the constant delivery pump and the hydraulic cylinder. This valve arrangement includes a variable delivery volume that mediates the control of hydraulic fluid flow to the three pressure chambers, enabling control of rapid traverse and power stroke without requiring a complex variable displacement pump control system

Inventive Principle:
Principle #24Intermediary (Mediator)

3Power

If larger drive motor power is used to handle both rapid traverse and power stroke, then sufficient power is available for all operations, but energy consumption and noise increase

Engineering Contradiction:
Improveavailable drive power for all operationsVSAvoidenergy consumption and noise
Core Design Contradiction:
PowerVSUse of energy by moving object

Solution Approach 1:

The patent employs a dynamic valve arrangement with variable delivery volume that adapts the hydraulic fluid flow characteristics to the specific operational mode. During rapid traverse, the valve configuration optimizes for high-speed low-force operation, while during power stroke, it optimizes for low-speed high-force operation. This dynamic adaptation allows a smaller drive motor to operate efficiently across different operating points, reducing overall energy consumption and noise

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 design allows for optimized control of the linear drive with minimized drive power, reducing noise and energy consumption across both operating points, enabling effective operation with a smaller drive motor and lower investment costs.

Implementation Method 1

the pressure chambers (4, 6, 8) can be pressurized via a hydraulic machine (10), preferably a pump, and a valve arrangement (20, 24), with high pressure (pump) or a low-pressure source, for example, tank pressure

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Data Source

PatentEP2420681B1Hydraulic linear drive device
Publication Date: 2020.01.08 ROBERT BOSCH GMBH
  • EP2420681B1 patent drawingFigure 1
  • EP2420681B1 patent drawingFigure 2
  • EP2420681B1 patent drawingFigure 3~4

AI summary

The hydraulic linear drive (1) has a hydraulic cylinder (2) which has three pressure chambers (4,6,8) that are limited to the working surfaces (A1,A2,A3), where the pressure chambers are charged with high pressure, low pressure or tank pressure over a hydro-machine (10) and a valve arrangement. The hydro-machine has a variable drive (12). The area ratios of the working surfaces are adjusted, so that the drive is operated in the same speed range.