Hydrostatic Drive Supply Pressure Control
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Solution Overview
Problem
Existing hydrostatic drives with closed circuits face inefficiencies due to constant supply pressure requirements, which do not adapt to varying demands, leading to increased power consumption and reduced efficiency, especially during partial load operations.
Innovation Solution
The implementation of a demand-driven supply pressure system using a hydraulic accumulator separated from the feed pump by a check valve, controlled by an electrical auxiliary system that adjusts supply pressure based on demand signals from the adjustment unit and drive control, incorporating an electrohydraulic pressure transducer for precise pressure regulation and an electrohydraulic actuator for pressure limiting, allowing for reduced supply pressure during low demand conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the supply pressure is held constant at 20-30 bar to ensure reliable pump adjustment, then the pump adjustment can be reliably actuated, but the driving power of the feed pump increases unnecessarily during partial load operations
Solution Approach 1:
The supply pressure is made dynamically adjustable rather than fixed. The control system varies the supply pressure according to actual demand: maintaining 20-30 bar when pump adjustment is required, and reducing to 5-15 bar during partial load operations. This dynamic adaptation resolves the contradiction by ensuring reliability only when necessary while reducing energy consumption during normal operation.
Solution Approach 2:
The supply pressure parameter is changed from a fixed value to a variable parameter controlled by the control system. The control system adjusts the supply pressure based on operational conditions, switching between high pressure (20-30 bar) for reliable adjustment and low pressure (5-15 bar) for energy-efficient partial load operation, thereby resolving the contradiction between reliability and energy consumption.
2Use of energy by moving object
If the supply pressure is reduced to lower power consumption, then the driving power of the feed pump decreases, but the pump adjustment may no longer be reliably actuated
Solution Approach 1:
The control system implements feedback control by monitoring operational conditions and adjusting the supply pressure accordingly. When pump adjustment is detected or required, the control system increases supply pressure to 20-30 bar to ensure reliable actuation. During partial load operations without adjustment demand, the pressure is reduced to 5-15 bar. This feedback mechanism ensures reliability is maintained only when necessary, resolving the contradiction.
Solution Approach 2:
The supply pressure is made dynamically responsive to actual system needs rather than being statically fixed. The control system continuously adapts the pressure level based on whether pump adjustment is required, creating a dynamic pressure profile that ensures reliability during adjustment operations while minimizing power consumption during steady-state partial load operation.
3Device complexity
If a fixed supply pressure system is used, then the system structure is simple, but the system cannot adapt to varying demand conditions
Solution Approach 1:
The control system automatically determines when pump adjustment is required and autonomously adjusts the supply pressure accordingly. The system monitors its own operational state and self-regulates the supply pressure without external intervention, adapting to varying demand conditions while maintaining a relatively simple overall structure. This self-service capability provides adaptability without proportionally increasing system complexity.
Solution Approach 2:
The control system serves multiple functions: it monitors operational conditions, determines adjustment requirements, controls supply pressure, and optimizes power consumption. This multi-functional control unit provides adaptability to varying demand conditions while integrating into the existing system architecture, thereby achieving versatility without proportionally increasing device complexity.
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 reduces power consumption and improves efficiency by dynamically adjusting supply pressure according to demand, optimizing hydrostatic drive performance and heat balance, particularly in partial load operations.
Implementation Method 1
the supply unit (6) consists of a hydraulic accumulator (9) and a check valve (18)
Implementation Method 2
the supply unit (6) consists of a hydraulic accumulator (9) and a check valve (18)
Implementation Method 3
The pressure of the supply pressure limiting valve is set by the auxiliary drive according to the determined demand, preferably by means of an electrohydraulic actuator
Implementation Method 4
an adjustable supply pressure limiting valve (12)
Implementation Method 5
an electrohydraulic pressure transducer for precise pressure regulation
Data Source
AI summary
A drive, which permits a lowering in the feed pressure provided by the feed pump and, at the same time, effects a supply to the displacement unit of the drive which meets the demand with regard to pressure and delivery volume. This is achieved in that the displacement unit (5) is supplied with hydraulic energy by an electro-hydraulic supply unit (6) wherein the supply unit (6) comprises a hydraulic reservoir (9) and a non-return valve (18) and is connected to the feed pressure limiting valve (12), which is implemented as an electrically adjustable pressure limiting valve, wherein the hydraulic reservoir (9) is also connected to an electro-hydraulic pressure sensor (10), which outputs the electric signal thereof to an electric auxiliary controller (11), and wherein the electric auxiliary controller (11) drives the feed pressure limiting valve (12). These hydraulic drives are used for example, in self-propelled working machines.