Hydraulic Filter Circuit with Bypass Valves for Contamination Control
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Solution Overview
Problem
Agricultural tractors' hydraulic systems are prone to contamination from various sources, including implement hydraulic components and couplers, which can compromise the integrity and efficiency of the hydraulic fluid circulation.
Innovation Solution
A filter circuit is integrated into the hydraulic system, comprising multiple filters and bypass valves to ensure continuous fluid purification, with suction and return filters connected in series with bypass valves, and a pressure-responsive backpressure valve to manage fluid flow and maintain system cleanliness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple filters are installed in series in the hydraulic system, then the filtration effectiveness is improved, but the pressure loss increases and may cause pump starvation
Solution Approach 1:
The suction filter is positioned to filter hydraulic fluid before it enters the pump, preventing contaminants from reaching the pump inlet. This preliminary filtration protects the pump while maintaining adequate pressure by filtering at the source rather than downstream where pressure drops would be more severe.
Solution Approach 2:
Bypass valves are introduced as intermediary components that activate when filter pressure differential exceeds a threshold. These bypass valves provide an alternative flow path around clogged filters, preventing excessive pressure loss while still allowing primary filtration to occur during normal operation.
2Reliability
If filters are installed in the hydraulic system, then contaminants are removed, but the system complexity increases with multiple filters and bypass valves
Solution Approach 1:
The filtration system is segmented into distinct functional components: suction filter for pump inlet protection, return filter for reservoir fluid cleanup, and bypass valves for each filter. This segmentation allows each component to be optimized for its specific function and simplifies maintenance by isolating individual filter elements.
Solution Approach 2:
The bypass valves serve multiple functions: they act as pressure relief valves when filters become clogged, provide backup filtration paths, and enable continuous system operation during filter maintenance. This multi-functionality reduces the need for additional separate components.
3Reliability
If suction filter is placed before the pump inlet, then pump protection is improved, but the filter may become clogged and starve the pump
Solution Approach 1:
The suction filter is installed at the pump inlet to preemptively remove contaminants before they can enter the pump. This preliminary protection prevents pump damage from abrasive particles while the bypass valve ensures continuous fluid supply by activating when the filter becomes clogged.
Solution Approach 2:
The bypass valve is pre-configured to activate when filter pressure differential reaches a critical threshold. This beforehand cushioning mechanism prevents pump starvation by providing an alternative unfiltered flow path before the filter completely blocks fluid supply, allowing the system to continue operating.
4Reliability
If return filter is installed to filter fluid before it enters the reservoir, then contaminant removal is improved, but pressure drop across the filter may affect system performance
Solution Approach 1:
The return filter is positioned in the return line where hydraulic fluid flows back to the reservoir after performing work. By extracting and filtering this fluid on its return journey, the system removes contaminants without interfering with the high-pressure working circuit, thus minimizing pressure drop impact on system performance.
Solution Approach 2:
A bypass valve is installed across the return filter to act as an intermediary. When the filter pressure differential becomes excessive, the bypass valve opens to provide an alternative flow path, preventing large pressure drops from affecting the main hydraulic circuit while still allowing filtered fluid to return to the reservoir.
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 filter circuit effectively protects the hydraulic system from contaminants by ensuring continuous filtration and maintaining adequate fluid supply to pumps, even when primary filters become clogged, thereby preventing system failure and ensuring reliable operation.
Implementation Method 1
A suction filter is connected between the sump line and the second filter circuit outlet
Implementation Method 2
A suction bypass filter is connected in series with a suction bypass valve between the sump line and the second filter circuit outlet
Implementation Method 3
A return filter is connected to an outlet of the first control circuit
Implementation Method 4
A return bypass filter is connected in series with a return bypass valve between an outlet of the first control circuit and the return line
Implementation Method 5
A pressure responsive backpressure valve has an outlet connected to the second filter circuit outlet, and has an inlet and a pressure sensing pilot line both connected to an outlet of the return filter. The backpressure valve also has a valve member biased by a spring to a normally closed position and movable to an open position in response to pressure in the pilot line
Implementation Method 6
The backpressure valve also has a valve member biased by a spring to a normally closed position
Data Source
AI summary
A vehicle hydraulic system includes a lube circuit, a pump supplying hydraulic fluid from sump to first and a second hydraulic control circuits and a filter circuit. The filter circuit includes a first outlet connected to the lube circuit, a sump line, and a second outlet connected to the pump. A suction filter is connected between the sump line and second outlet. A return filter is connected to the first control circuit outlet. A return line having an orifice is connected between the return filter and the first outlet. A backpressure valve has a member, an outlet connected to the second outlet, and an inlet and pilot line connected to the return filter outlet. A pressure sense line has one end connected to the return line between the orifice and the first outlet, and a second end connected to the member in opposition to the pilot line.