Heat Pipe Cooling for Hydraulic Reservoirs

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Solution Overview

Problem

Existing cooling devices for hydraulic units are inefficient as they require the hydraulic unit to be operational to cool the pressure medium, lead to hydraulic losses, and increase production costs due to additional components and complexity, while also being prone to noise and leakage.

Innovation Solution

A cooling device utilizing at least two heat pipes immersed in a container for hydraulic oil, allowing heat dissipation even when the hydraulic unit is not in operation, with a geometric arrangement that minimizes flow losses and requires less installation space, using heat pipes and a cooling structure that promotes heat transfer and can be cooled by forced convection or a heat exchanger.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a radiator cooled by air from a fan is used to cool hydraulic fluid, then cooling is achieved during pump operation, but the cooling capacity is not constant and depends on system pressure, and cooling is only possible during operation

Engineering Contradiction:
Improvehydraulic fluid temperatureVSAvoidcooling capacity constancy
Core Design Contradiction:
TemperatureVSProductivity

Solution Approach 1:

The patent replaces the mechanically dependent cooling system (radiator requiring pump operation and airflow) with a thermally passive heat pipe system that automatically transfers heat without mechanical drive, enabling constant cooling capacity independent of system pressure and operational state

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The heat pipe utilizes phase transition of the working fluid (evaporation at hot end, condensation at cold end) to transfer heat from hydraulic fluid to cooling fins, providing continuous cooling regardless of pump operation or system pressure conditions

Inventive Principle:
Principle #36Phase transitions

2Temperature

If two pumps (dual pump) are used to provide flow for cooling circuit, then cooling capability is provided, but additional pump increases complexity, manufacturing costs, noise, piping effort, leakage risk, and hydraulic losses

Engineering Contradiction:
Improvehydraulic fluid temperatureVSAvoidpump system complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent extracts the cooling function from the hydraulic pump system by implementing a separate heat pipe-based cooling device that operates independently, eliminating the need for an additional cooling pump and its associated complexity, piping, and hydraulic losses

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The heat pipe serves multiple functions: it provides cooling for hydraulic fluid during pump operation, during standby, and after shutdown, replacing the need for separate cooling pump and radiator system while reducing overall system complexity

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

3Productivity

If heat pipes are used for cooling the reservoir, then cooling is possible during and outside operation with improved efficiency and less installation space, but heat dissipation to surroundings must be enhanced

Engineering Contradiction:
Improvecooling efficiencyVSAvoidheat dissipation capability
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

The heat pipe is pre-filled with appropriate amount of working fluid and sealed to contain the phase-change medium, enabling immediate heat transfer functionality upon immersion in hydraulic fluid without requiring additional setup or activation

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The heat pipe extends vertically from the reservoir bottom with its evaporator section immersed in hydraulic fluid and condenser section exposed to ambient air, creating a three-dimensional heat transfer path that maximizes heat dissipation surface area and thermal efficiency

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 solution provides efficient cooling of hydraulic oil both during and outside of the hydraulic unit's operation, reduces installation space, and enhances heat transfer efficiency, while being compact and cost-effective by leveraging heat pipes and a cooling structure that can be cooled through forced convection or a heat exchanger.

Implementation Method 1

The cooling device has at least two, preferably three, heat pipes (12, 14, 16), each of which is immersed in the reservoir (2) by a pipe section (18)

Methodology Applied
Scientific EffectHeat pipe: Heat Pipe

Implementation Method 2

can be cooled by forced convection or a heat exchanger

Methodology Applied
Scientific EffectForced convection: Forced Convection

Implementation Method 3

can be cooled by forced convection or a heat exchanger

Methodology Applied
Scientific EffectHeat exchanger: Heat Exchanger

Data Source

PatentEP3224484B1Cooling device for a hydraulic assembly and use of a cooling device
Publication Date: 2020.09.02 ROBERT BOSCH GMBH
  • EP3224484B1 patent drawingFigure 1~2
  • EP3224484B1 patent drawingFigure 3~4
  • EP3224484B1 patent drawingFigure 5~6

AI summary

The invention relates to a cooling device for a hydraulic assembly which has a container for hydraulic oil. There is a heat pipe for cooling the container. Hydraulic oil in the container flows approximately in a straight line from an inlet to an outlet. The at least one heat pipe is arranged between the inlet and the outlet.