Hydrostatic Steering Circuit for Energy-Free Fault Centering
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Solution Overview
Problem
Existing hydrostatic control circuits for steering systems are complex and prone to errors, requiring energy to center the steering in case of a fault, and often lack simplicity in design.
Innovation Solution
A hydrostatic control circuit with a minimal component count, featuring a directional control valve and non-return valves arranged in a mirror-inverted configuration, allows unidirectional flow between the actuator's chambers, enabling the piston rod to move only towards the central position, thus centering the steering without energy supply in fault conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex steering system with multiple cylinders and blocking valves is used to enable fault-safe centering, then the steering can be brought into central position after an error, but the device complexity increases significantly
Solution Approach 1:
The patent extracts the centering function from a separate centering cylinder and blocking valves, and integrates it directly into the steering cylinder's piston rod design. The piston rod itself becomes the centering device through its geometric shape, eliminating the need for additional centering components and reducing overall system complexity while maintaining fault-safe centering capability.
Solution Approach 2:
The piston rod is designed to serve multiple functions: it acts as both the steering actuator and the centering device. The geometrically shaped piston rod automatically centers the steering when fluid pressure is released, combining the functions of steering control and fault-safe centering into a single component, thereby reducing the number of required components.
2Reliability
If additional centering cylinder and blocking valves are added to enable fault-safe centering, then the steering can be returned to neutral position, but the quantity of components increases
Solution Approach 1:
The patent merges the centering function with the steering cylinder by designing the piston rod with a specific geometric shape. This integration eliminates the need for a separate centering cylinder and blocking valves, reducing the total number of components while ensuring that the steering can be automatically centered in the event of a fault.
Solution Approach 2:
The geometrically shaped piston rod automatically performs the centering function without requiring additional control valves or external energy input. When fluid pressure is released, the piston rod's geometry causes it to automatically return to the neutral position, enabling self-centering and reducing the need for additional active components.
3Use of energy by moving object
If a directional control valve and non-return valves are used to enable unidirectional flow for centering, then the steering centers without energy supply, but the device complexity increases
Solution Approach 1:
The patent uses hydraulic principles with non-return valves to create a passive centering mechanism. The valves are configured to allow fluid flow in only one direction, automatically centering the steering when pressure is released without requiring external energy input or complex active control systems.
Solution Approach 2:
Instead of using active control to center the steering, the patent inverts the approach by using passive hydraulic elements (non-return valves) that automatically enforce unidirectional flow. This passive inversion eliminates the need for energy-consuming active centering mechanisms while achieving the same functional result.
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 effectively centers the steering system in case of a fault without energy supply, ensuring reliability and simplicity by using a reduced number of components and leveraging the mechanical properties of the piston rod and check valves.
Implementation Method 1
The directional control valve blocks or closes in its one operating position and opens in its other operating position, in particular under the action of at least one spring
Implementation Method 2
two non-return valves 66 and 68, which are arranged in a mirror-inverted manner in terms of circuitry
Implementation Method 3
opens in its other operating position, in particular under the action of at least one spring 65
Implementation Method 4
a reversible hydraulic pump 20 with two connections 21, 22, of which each connection 21 or 22 via connecting lines 41, 42 or 51, 52 to one of two chambers 31 or 32 of a control element 34 with a hydraulic actuator 30 in the form of a double-acting steering cylinder
Data Source
Figure 1
Figure 2
AI summary
The problem addressed by the invention is that of developing a hydrostatic control circuit (100), in particular as an auxiliary steering system in utility vehicles, comprising: a hydraulic pump (20), which has two connections (21, 22) and, in particular, can be reversed, of which connections each connection (21, 22) leads, via connecting lines (41 ,42, 51, 52), to one of two chambers (31, 32) of at least one hydraulic actuator (30) having a control element (34), wherein a check valve (25, 28) is arranged between each of the two connections (21, 22) and the chamber (31, 32) associated with the particular connection (21, 22) and wherein after the one activation of the hydraulic pump (20), a certain volumetric flow of hydraulic fluid is conducted from the one connection (21) acting as a pressure connection into the one chamber (31) via a first segment (41) of a first connecting line, the first check valve (25), and a second segment (51) of the first connecting line, the control element (34) thus being translated, and hydraulic fluid is displaced from the other chamber (32) to a tank (46) via a second segment (52) of a second connecting line, the second pressure valve (27), which is brought into a control position by the incoming volumetric flow, and a tank line (45), wherein the two chambers (31, 32) have substantially the same effective areas; in such a way that only very few components are required and the steering system can be brought into the center position in the event of a fault without having to supply energy to the system. This problem is solved, according to the invention, in that the two chambers (31, 32) are connected to a device (70), in particular by means of lines (61, 62), the components of which device can be put into a switching state as a result of the deflection of the hydraulic actuator (30) from the center position of the hydraulic actuator, which switching state enables unidirectional flow between the two chambers (31, 32) in such a way that a piston rod (36) of the hydraulic actuator (30) can be moved only toward the center position.