Attachment Hydraulic Load-Signal Control for Pressure Loss Compensation
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Solution Overview
Problem
Hydraulic systems in agricultural and construction machines face inefficiencies due to power losses and pressure variations when multiple hydraulic functions are activated simultaneously, leading to insufficient volume flow and pressure issues in attachments connected via power-beyond connections.
Innovation Solution
A load signal control system within the working hydraulic system of the attachment, featuring a pressure control valve connected to both the primary and secondary load signal lines, dynamically adjusts pressure to match the volume flow requirements of consumers, using an electro-hydraulically proportional pressure control valve to compensate for pressure losses and optimize energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a variable-displacement hydraulic pump with load-sensing system is used, then energy efficiency is improved and power losses are reduced, but pressure losses in connections between pump and implement can occur causing insufficient flow rate
Solution Approach 1:
A secondary load signal line is introduced as an intermediary between the primary load signal line and the pressure compensator. This secondary line includes a pressure control valve that can independently regulate pressure to compensate for losses in the power-beyond connections, ensuring reliable flow rate supply while maintaining the energy efficiency of the load-sensing system.
Solution Approach 2:
The system changes the pressure parameter in the secondary load signal line independently from the primary load signal line. The pressure control valve adjusts the secondary load pressure to account for connection losses, allowing the pump to maintain adequate flow rate without increasing overall system energy consumption.
2Productivity
If multiple hydraulic functions are activated simultaneously, then productivity is improved, but pressure losses increase leading to insufficient volume flow
Solution Approach 1:
The secondary load signal line acts as a mediator that compensates for pressure losses occurring when multiple hydraulic functions are activated simultaneously. The pressure control valve in this secondary line ensures adequate volume flow is maintained despite the increased demand and associated pressure losses.
Solution Approach 2:
The system uses feedback from the primary load signal line (which senses the actual load pressure) to control the pressure control valve in the secondary load signal line. This feedback mechanism ensures that the secondary pressure compensates for losses and maintains sufficient volume flow for all activated hydraulic functions.
3Ease of operation
If power-beyond connections are used to connect implements, then ease of operation is improved, but pressure losses in connections cause control signal failure
Solution Approach 1:
The secondary load signal line serves as an intermediary control path that compensates for pressure losses in the power-beyond connections. By independently regulating pressure in this secondary line, the system prevents control signal failure while maintaining the ease of operation provided by the power-beyond connection system.
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
Ensures reliable and efficient operation by adapting pressure and flow to meet the demands of all hydraulic consumers, reducing leakage losses and enabling precise control of actuating speeds, while maintaining efficient standby operation and fail-safe functionality.
Implementation Method 1
a primary load pressure can be generated in a primary load signal line, wherein the primary load pressure is supplied to a control unit that controls a volume flow in a pressure line leading to the at least one consumer
Implementation Method 2
in the control unit a demand-based pressure increase of the primary load pressure to a pressure level of a secondary load pressure takes place
Implementation Method 3
The delivery rate of the variable-displacement hydraulic pump is regulated by a load-sensing system
Implementation Method 4
The compensator then determines the system's energy demand by comparing the load pressure and the pump pressure
Data Source
Figure 1
Figure 2
Figure 3~3a
AI summary
A load signal control system for the working hydraulics (25) of an implement is connected to a hydraulic system (1, 44) of an agricultural or construction machine via at least one pressure connection (P) and one tank connection (T). The working hydraulics (25) includes at least one consumer (36) controlled by a directional control valve (35), through which a primary load pressure (pLS_primary) can be generated in a primary load signal line (17"). This primary load pressure (pLS_primary) is supplied to a control unit (26), which controls a flow rate in a pressure line (10') leading to the at least one consumer (36). In the control unit (26), the pressure of the primary load pressure (pLS_primary) is increased as required to a pressure level corresponding to a secondary load pressure (pLS_secondary).In order to provide means for the working hydraulics of an attachment connected to an agricultural or construction-related work machine, by means of which all consumers provided in the working hydraulics are supplied with pressure medium as required, the control unit (26) shall be arranged within the working hydraulics (25) of the attachment and shall have a pressure regulating valve (38) which is connected on the inlet side to the pressure line (10') and the primary load signal line (17") and on the outlet side to a secondary load signal line (17'), wherein a control piston of the pressure regulating valve (38) is acted on one side by the primary load pressure (pLS_primary) and on the other side by the secondary load pressure (pLS_secondary) and optionally by a compression spring.