Preselection Valve Load-Pressure Boosting With Low Preload
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Solution Overview
Problem
Existing hydraulic preselection valves face inefficiencies in energy consumption due to high preload pressures, which lead to increased energy usage and weight, especially in mobile hydraulics, as they require high load pressure signals to function effectively, and reducing preload pressure is not feasible without compromising system performance.
Innovation Solution
A preselection valve design featuring a second load pressure line and a load pressure increasing device, which taps the load pressure signal before the switching element and increases it independently of flow quantity, allowing for a lower overall preload pressure, thereby reducing energy consumption and maintaining desired flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If high preload pressure is used in the recirculating pressure compensator, then sufficient basic pressure is available to switch the switching element hydraulically and maintain system pressure, but energy consumption increases significantly
Solution Approach 1:
The pressure supply path is segmented into two independent sources: a high-pressure source (pump 104) connected to pressure input line 3 and a low-pressure source (pressure compensator 105) connected to load pressure line 8. The switching element 2 can be actuated by the high-pressure source while the load pressure line receives compensated pressure from the low-pressure source, eliminating the need for high preload pressure in the compensator.
Solution Approach 2:
The preselection valve 1 acts as an intermediary device that decouples the switching element actuation from the load pressure compensation. It receives high-pressure fluid for switching element actuation and separately receives low-pressure compensated fluid for the load pressure line, allowing the pressure compensator to operate with low preload pressure while maintaining sufficient pressure for system operation.
2Reliability
If high preload pressure is used to ensure sufficient flow rate to control spools, then the switching element can be actuated reliably, but the required flow rate does not reach the control spools due to backpressures
Solution Approach 1:
The hydraulic circuit is segmented into two independent pressure supply paths: one path (pressure input line 3) provides high pressure for switching element actuation, and another path (load pressure line 8) provides compensated pressure to the control spools. This segmentation allows each path to be optimized independently, ensuring sufficient flow rate to control spools without being constrained by high backpressures required for switching element actuation.
3Stress or pressure
If a throttle is added downstream of the switching element to generate sufficient load pressure signal, then the load pressure signal increases, but the channel in the switching element also forms a hydraulic resistor making the signal strongly quantity-dependent
Solution Approach 1:
The load pressure signal is tapped from the pressure input line 3 upstream of the switching element 2, before the fluid passes through the switching element's internal channels. This preliminary tapping ensures that the load pressure signal is generated from the high-pressure source directly, without being degraded by the hydraulic resistance of the switching element's internal passages or downstream throttles.
Solution Approach 2:
The load pressure signal is extracted from the high-pressure line upstream of the switching element, separating the signal generation function from the switching function. This extraction allows the load pressure signal to be obtained directly from the pump's high-pressure output without being affected by the switching element's internal hydraulic resistance or requiring additional downstream throttles.
4Use of energy by moving object
If preload pressure is reduced to decrease energy consumption, then energy efficiency improves, but the load pressure signal becomes insufficient for proper system operation
Solution Approach 1:
The pressure supply is segmented into two independent sources: the pressure input line 3 receives high-pressure fluid from the pump for switching element actuation and load pressure signal generation, while the load pressure line 8 receives low-pressure compensated fluid from the pressure compensator 105. This segmentation allows the load pressure signal to be maintained at high levels from the pump while the pressure compensator operates with low preload pressure, achieving both energy efficiency and sufficient load pressure signal.
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 design achieves energy efficiency by lowering preload pressure to 4 bar or less, reducing energy consumption, and ensuring sufficient flow rates to control spools, while maintaining high load pressure signals when needed, thus optimizing hydraulic system performance.
Implementation Method 1
the first hydraulic resistor 14 and the second hydraulic resistor 15 can be formed as nozzles
Data Source
AI summary
A preselection valve is for a hydraulic valve assembly with a switching element, a pressure input line, a first pressure output line and a first load pressure line with a load pressure inlet and output. The switching element is switchable from neutral to a first switching position. The pressure input line is connected to the first pressure output line in the first position. The preselection valve has a second and third load pressure line and a load pressure increasing device. The second load pressure line branches off the pressure input line upstream of the switching element. The load pressure increasing device is connected to the third load pressure line, which connects the pressure increasing device to the first load pressure line. The second load pressure line is connected to the pressure increasing device in the first switching position and the second load pressure line is blocked in the neutral position.