Hydrostatic Fan Drive with Hydraulic Accumulator
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Solution Overview
Problem
Hydrostatic fan drives for internal combustion engines are limited by their coupling to the driving engine, preventing fan operation when the engine is switched off and reducing maximum power output when maximum power is needed.
Innovation Solution
A hydrostatic fan drive system that includes a primary unit driven by the internal combustion engine, a fan motor, and a hydraulic accumulator connected to a high-pressure line, allowing fan operation even when the engine is off and enabling increased temporary power by supplying the fan motor with pressure medium from the accumulator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the fan drive is directly coupled to the internal combustion engine, then the fan can be driven by the engine, but the fan cannot operate when the engine is switched off
Solution Approach 1:
A hydraulic accumulator is introduced as an intermediary energy storage device between the engine and fan motor. The accumulator stores hydraulic energy when the engine is running and releases it when the engine is off, enabling fan operation independent of engine status without requiring complex direct coupling mechanisms
Solution Approach 2:
The direct mechanical coupling between engine and fan is extracted/replaced by a hydraulic circuit with accumulator. This separates the fan drive system from direct engine dependency, allowing the fan to operate independently when the engine is switched off
2Power
If maximum power is drawn from the internal combustion engine, then the engine power output is maximized, but the fan operation reduces the available power
Solution Approach 1:
The hydraulic accumulator is charged with hydraulic energy in advance when the engine is running or during braking. This preliminary energy storage allows the fan motor to draw power from the accumulator rather than directly from the engine, preserving engine maximum power output when needed
Solution Approach 2:
Energy that would otherwise be lost during braking is recovered and stored in the hydraulic accumulator. This recovered energy is then available to power the fan motor, reducing the burden on the engine and increasing available power for other functions
3Ease of operation
If a pressure-reducing valve is used to control fan output, then the fan speed can be regulated, but energy is lost through the lossy valve
Solution Approach 1:
The mechanical pressure-reducing valve system is replaced with a variable displacement axial piston machine that can adjust its delivery volume. This substitution eliminates the lossy throttling mechanism and replaces it with an efficient variable displacement pump that maintains pressure while controlling flow to the fan motor
Solution Approach 2:
The system changes the control parameter from pressure reduction (lossy) to delivery volume adjustment (efficient). The axial piston machine varies its piston displacement to control fan output, maintaining system pressure while adjusting power delivery to match fan requirements without energy loss
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
Enables fan operation independent of the engine's status and increases the engine's maximum power output by using the accumulator to supply the fan motor, reducing the need for a lossy pressure-reducing valve and allowing energy recovery during braking.
Implementation Method 1
A hydraulic accumulator is connected to a high-pressure line that connects the primary unit to the fan motor
Implementation Method 2
a variable displacement pump driven by the internal combustion engine, which drives a fan wheel via a constant motor
Implementation Method 3
a fan motor which can be used to drive a fan wheel
Data Source
AI summary
The invention relates to a hydrostatic fan drive for internal combustion engines, having a primary unit that can be driven by the internal combustion engine, and having a fan motor by means of which a blower fan can be driven. A hydraulic reservoir is disposed at a high-pressure line connecting the primary unit to the fan motor. A hybrid fan drive for internal combustion engines is thus provided, allowing fan operation even if the internal combustion engine is switched off. An increased maximal available power of the internal combustion engine is available in transition, despite the fan operation, because the fan motor can be supplied with pressurized media by the hydraulic reservoir in such cases (in transition).