Hydrostatic Drive Pressure Cut-Off Without Pressure Sensors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional hydrostatic travel drives face challenges with complex and costly pressure cut-off systems, susceptibility to vibrations, and energy losses due to the use of hydromechanical controllers and pressure sensors, which lead to unstable behavior and reduced control accuracy.
Innovation Solution
A hydrostatic travel drive with an electronically controllable pressure valve that limits actuating pressure through a model-based approach, allowing for calibration and automatic adjustment, eliminating the need for pressure sensors and reducing complexity and energy losses, while ensuring stable pressure control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a hydromechanical pressure relief valve is used for pressure cut-off, then pressure limitation is achieved, but equipment cost increases and energy loss occurs due to venting control fluid
Solution Approach 1:
The patent replaces the hydromechanical pressure relief valve with an electronic pressure control system that uses a pressure sensor, electronic control unit, and electronically controlled pressure valve. This substitution eliminates the need to vent control fluid to the tank, thereby preventing energy loss while achieving pressure limitation through electronic regulation of the actuating pressure.
2Stress or pressure
If a hydromechanical pressure relief valve is used for pressure cut-off, then pressure limitation is achieved, but device complexity and equipment cost increase
Solution Approach 1:
The patent replaces the complex hydromechanical pressure relief valve mechanism with a more compact electronic control system consisting of a pressure sensor, electronic control unit, and electronically controlled pressure valve. This substitution reduces device complexity by eliminating mechanical linkages, springs, and the need for separate pressure relief valve components while achieving the same pressure limitation function.
3Stress or pressure
If electronic pressure control based on pressure sensor readings is used, then pressure cut-off is achieved, but the system becomes prone to vibrations and complex
Solution Approach 1:
The patent implements a feedback control system where the pressure sensor continuously monitors the actuating pressure and feeds this information to the electronic control unit. The control unit compares the measured pressure with the desired setpoint and adjusts the electronically controlled pressure valve accordingly. This closed-loop feedback mechanism provides stable pressure control and reduces vibrations by making gradual, precise adjustments rather than abrupt mechanical responses.
Solution Approach 2:
The patent employs dynamic pressure control through the electronic control unit that can rapidly adjust the actuating pressure in response to changing operating conditions. The electronically controlled pressure valve provides dynamic response with adjustable opening characteristics, allowing the system to adapt to transient conditions smoothly and maintain stability during transitions between different operating states.
4Stress or pressure
If electronic pressure control with pressure sensor is used, then pressure cut-off is achieved, but cost increases due to high requirements for accuracy and robustness
Solution Approach 1:
The patent integrates the pressure sensor and electronic control unit into the existing hydrostatic drive system, where the pressure sensor serves multiple functions: monitoring actuating pressure for control purposes, detecting pressure spikes, and providing feedback for calibration. The electronic control unit performs multiple tasks including pressure regulation, calibration management, and system diagnostics. This multi-functionality reduces the need for dedicated components and lowers overall system cost.
Solution Approach 2:
The patent implements a self-calibration function where the electronic control unit automatically adjusts the pressure control characteristics based on measured operating conditions. The system can perform self-diagnosis and self-adjustment without requiring external calibration equipment or manual intervention, thereby reducing the need for high-precision external calibration tools and reducing overall system cost while maintaining accuracy.
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 a more stable and cost-effective pressure control with reduced susceptibility to vibrations, enabling accurate calibration and compensation for hydraulic pump changes over its service life, without the need for manual adjustments or complex sensor systems.
Implementation Method 1
a hydraulic pump (2) which can be coupled to a drive motor... The hydraulic pump is designed with an adjustable displacement volume VP and an actuating cylinder (10) with at least one cylinder chamber (12) for adjusting this volume
Implementation Method 2
To apply an actuating pressure pa to the at least one cylinder chamber (12) that acts on the stroke volume VP, at least one electrically controlled pressure valve (18) is provided and assigned to the cylinder chamber (12)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A hydrostatic drive system is disclosed, comprising a hydraulic pump for supplying hydraulic fluid to a hydraulic motor of the drive system. The hydraulic pump has an actuating cylinder with at least one cylinder chamber and an adjustable stroke volume, and at least one electrically controlled pressure valve is provided through which the cylinder chamber can be pressurized with an actuating pressure. Furthermore, the drive system has a device by which the pressure of the hydraulic pump can be limited by influencing the actuating pressure. A method for controlling the drive system is also disclosed.