Open-Circuit Hydrostatic Traction Drive for Adaptive Braking Torque
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Solution Overview
Problem
Hydrostatic traction drives face inefficiencies due to fixed working pressures and limited torque control in both closed and open circuits, leading to suboptimal performance and increased energy losses during braking operations.
Innovation Solution
A hydrostatic traction drive with adjustable displacement volumes in both primary and secondary units connected via an open circuit, featuring an electronic control unit for variable pressure regulation and torque control, allowing for optimized working pressure adaptation and independent adjustment of secondary-side braking torque and primary-side supporting torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a closed circuit is used with pressure-limiting valves for each case, then braking operation is possible, but device complexity increases and separate circuits are required
Solution Approach 1:
The open circuit configuration allows a single working line to serve multiple functions: it acts as the high-pressure line for both driving and braking operations, eliminating the need for separate circuits for different operating modes. The circuit can universally handle both acceleration and braking without requiring additional pressure-limiting valves for each case.
Solution Approach 2:
The invention extracts and removes the unnecessary pressure-limiting valves and separate circuits from the system by transitioning to an open circuit configuration. This simplifies the overall system structure while maintaining the essential braking functionality through the primary machine's drag torque capability.
2Stability of the object's composition
If hydraulic accumulators are used to stabilize pressure in open circuit, then torque regulation is possible, but working pressure can be adjusted only within limits and efficiency is reduced
Solution Approach 1:
The electronic control unit implements a feedback control system that continuously monitors the actual working pressure via a pressure sensor and adjusts the displacement volume of the primary or secondary unit accordingly. This closed-loop control maintains precise pressure stability and optimizes efficiency by adapting the displacement volume to match the actual torque demand, eliminating the need for hydraulic accumulators with limited adjustment ranges.
Solution Approach 2:
The system transitions from static pressure regulation with fixed accumulators to dynamic pressure control where the displacement volume of the hydrostatic units is continuously adjusted based on real-time pressure feedback. This dynamic adaptation allows the system to maintain optimal efficiency across varying operating conditions while ensuring pressure stability.
3Device complexity
If displacement volume is fixed in hydrostatic units, then system structure is simple, but torque control and pressure adaptation are limited
Solution Approach 1:
The invention changes the key parameter of displacement volume from a fixed value to a variable parameter that can be continuously adjusted. The electronic control unit modifies the displacement volume of the primary or secondary unit based on the detected working pressure and torque demand, enabling precise torque control and pressure adaptation while maintaining relatively simple system architecture.
Solution Approach 2:
The hydrostatic units are designed with adjustable displacement volume capability, transforming them from static to dynamic components. This allows the system to adapt torque output and working pressure to varying operational requirements without significantly increasing structural complexity, as the adjustment mechanism is integrated into the existing hydrostatic unit design.
4Reliability
If primary machine drag torque is limited, then engine safety is protected, but braking power is reduced
Solution Approach 1:
The electronic control unit dynamically adjusts the displacement volume of the secondary unit during braking operation to optimize the balance between braking power and primary machine safety. By continuously adapting the displacement volume based on real-time pressure and torque feedback, the system maximizes braking power utilization while ensuring the primary machine operates within its safe drag torque limits, preventing both underutilization and overloading.
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 configuration enhances efficiency by allowing continuous variable pressure adjustment and precise control of braking torque, maximizing braking power while minimizing energy losses and preventing overloading of the primary machine.
Implementation Method 1
a first working line (P) connects the two units (1, 2) to one another
Implementation Method 2
both units (1, 2) being adjustable in their displacement volume
Implementation Method 3
the pressure-regulated unit or the working line has a pressure sensor
Implementation Method 4
the torque-controlled or pivot-angle-regulated unit preferably has a rotational speed sensor
Data Source
AI summary
A hydrostatic traction drive includes a hydrostatic pump and a hydrostatic motor connected to each other in an open circuit. One of the pump and motor is pressure-regulated while the other is torque-controlled or regulated in terms of pivot angle. A braking mode is therefore possible in which the secondary-side braking torque can be adapted to the permissible primary-side supporting torque of a primary machine coupled to the pump. To further increase the braking power, even in a high rotational phase of the primary machine, the permissible drag torque thereof can be temporarily exceeded. To further increase the braking power and therefore to have high-performance braking during operation, further means for converting energy can be provided in order to adjust a secondary-side braking torque and a primary-side supporting torque independently of each other.