Hydrostatic Transmission Pressure Relief Valve
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Solution Overview
Problem
Existing hydrostatic drive systems face issues with dynamic pressures and low pressure drops in working lines, leading to inefficiencies and potential damage during deceleration and coasting modes, particularly in systems with long pressure relief valve lines and reliance on hydraulic fluid pressure accumulators.
Innovation Solution
A closed hydraulic fluid circuit with adjustable hydraulic pump and motor conveying volumes, utilizing a direct connection line with a pressure relief valve between the outlet and inlet to manage pressure and flow rates, preventing excessive pressure and ensuring constant pressure limits, thereby reducing kinetic energy transformation into heat and minimizing the need for hydraulic fluid accumulators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure relief valves are arranged in branch lines splitting off from working lines, then pressure can be relieved to prevent damage, but dynamic pressures occur and low pressure drops arise in long high pressure lines
Solution Approach 1:
The patent relocates the pressure relief valve from a branch line configuration to the main working line between hydraulic motor and pump. This dimensional repositioning in the hydraulic circuit allows the valve to directly manage pressure in the high-pressure zone without creating long branch lines, thereby eliminating dynamic pressure effects and low pressure drops while maintaining reliable pressure protection.
Solution Approach 2:
The pressure relief valve acts as an intermediary element directly positioned in the working line between hydraulic motor and pump. It mediates pressure control by providing a controlled pressure relief path that prevents excessive pressure buildup while avoiding the harmful dynamic effects associated with long branch line configurations.
2Stress or pressure
If pressure relief valves are arranged in the hydraulic pump, then pressure can be controlled, but the supply lines from hydraulic motor to pressure relief valves become very long causing dynamic pressures
Solution Approach 1:
The patent repositions the pressure relief valve from the hydraulic pump location to an intermediate position directly between the hydraulic motor and pump in the working line. This spatial reconfiguration dramatically reduces the length of high-pressure supply lines, eliminating dynamic pressure effects while maintaining effective pressure control at the source of pressure generation.
3Quantity of substance
If the conveying volume of hydraulic motor is increased to compensate for low pressure drops, then more hydraulic fluid can be supplied, but kinetic energy transformation into heat increases
Solution Approach 1:
The patent converts the potential harm of excessive pressure relief (which would waste kinetic energy as heat) into a benefit by precisely positioning the pressure relief valve to control pressure at the optimal location. This allows the system to maintain adequate hydraulic fluid flow rates without excessive pressure relief, thereby minimizing unnecessary kinetic energy conversion to heat while still preventing low pressure drops.
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 provides a robust, cost-effective, and quick-reacting hydrostatic transmission system that maintains constant pressure, optimizes deceleration performance, and reduces wear on mechanical brake systems by efficiently managing hydraulic fluid flow and pressure, ensuring maximum deceleration capability without excessive heat conversion.
Implementation Method 1
a pressure relief valve (20) arranged in this connection line (14), which can be passed through in flow direction from the outlet (13) to the inlet (12)
Implementation Method 2
a partial flow rate of the hydraulic fluid flow rate conveyed by the hydraulic motor (5), respectively of the drive mechanism (11), is released, what results in a transformation of kinetic energy into heat
Implementation Method 3
a hydraulic pump (4) drivable by a drive engine (2) and a hydraulic motor (5) are arranged in a closed hydraulic fluid circuit
Implementation Method 4
The hydraulic pump (4) as well as the hydraulic motor (5) is adjustable in its conveying volume
Data Source
AI summary
Hydrostatic transmission and method for decelerating a hydrostatic transmission with a closed hydraulic fluid circuit, in which a hydraulic pump drivable by a drive engine and a hydraulic motor are arranged and connected fluidly to one another through two working lines. Alternately depending on the operational mode and on the conveying direction of the hydraulic pump, one working line is the low pressure line and the other one is the high pressure line. The hydraulic pump as well as the hydraulic motor are adjustable in their respective displacement volumes by means of a control unit. The hydraulic motor comprises a housing in which a hydrostatic drive mechanism having an inlet and an outlet is arranged. In a connecting line connecting the outlet and the inlet a pressure control valve is arranged, which can be flown through in direction to the inlet. The pressure control valve opens if the high pressure present at the outlet exceeds a predetermined pressure limit of the pressure relief valve. During the coasting operation of the hydrostatic transmission the displacement of the hydraulic pump and/or of the hydraulic motor are adjustable by means of the control unit in function of the speed of the drive motor or of the speed of the hydraulic pump.