Pilot-Operated Hydraulic Valve Bushing for High-Flow Low-Pressure Drop
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Solution Overview
Problem
Existing pilot-operated hydraulic directional cartridge valves face limitations in achieving high volume flows without unacceptable pressure drops, due to standardized dimensions that restrict the optimization of flow cross-sections and sealing diameters.
Innovation Solution
The design incorporates a cartridge bushing with specific sealing diameters and radial openings, a control slide with a guide diameter ratio between 1.10 and 1.28, and a second bushing section with a larger outer diameter, allowing for a large inner diameter and annular channel to facilitate high volume flows while maintaining effective sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the bushing has a large inner diameter to enable high flow rates, then the flow cross-section is increased, but the structural strength and sealing capability are reduced
Solution Approach 1:
The bushing is designed with varying wall thicknesses at different locations: thinner walls in the central flow area (larger inner diameter) to maximize flow cross-section, and thicker walls at the sealing sections (first and third bushing sections) to maintain structural strength and sealing capability. This local differentiation of properties resolves the contradiction between flow rate and strength.
2Productivity
If the guide diameter is increased to match the large inner diameter, then the control spool can be made larger for high flow rates, but the ratio between sealing diameter and guide diameter becomes difficult to maintain within standard ranges
Solution Approach 1:
The bushing incorporates distinct sections with different functional characteristics: the second bushing section has a larger inner diameter for flow control, while the first and third bushing sections maintain standardized sealing diameters. This allows the guide diameter to be optimized for flow while keeping sealing diameters within standard ranges, maintaining the required dimensional ratios.
3Productivity
If the outer diameter of the bushing is reduced in the second section to increase the annular channel width, then flow capacity is improved, but the sealing surface area is reduced
Solution Approach 1:
The bushing design features a localized reduction in outer diameter specifically in the second bushing section to maximize the annular channel width and flow capacity, while the first and third bushing sections maintain larger outer diameters to provide adequate sealing surface area. This spatial differentiation resolves the contradiction between flow capacity and sealing area.
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 configuration enables large volume flows in both directions with minimal pressure drop, ensuring efficient hydraulic fluid flow and reduced risk of cracking or fracture through optimized diameters and relief notches.
Implementation Method 1
enables large volume flows in both directions with minimal pressure drop, ensuring efficient hydraulic fluid flow
Implementation Method 2
Both bushing sections are typically provided with a circumferential annular groove on the outside, into which a sealing ring is inserted
Implementation Method 3
The control spool has a spool collar for its hydraulic actuation... pressure medium is supplied to one control chamber via a pilot valve and pressure medium is discharged from the other control chamber
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The invention relates to a pilot-operated hydraulic directional control valve with a mounting bushing (15) to be inserted into a mounting bore (31) of a hydraulic block (30), which has an inner bore (16) and which has a first bushing section (34) with a first outer sealing diameter (D1) towards its front end face (29) and a third bushing section (42) with a second outer sealing diameter (D3) that is larger than the sealing diameter in the first bushing section and in between a second bushing section (37) in which it has a series of radial openings (45) and in which it has an outer diameter (D2) in the area and over a certain distance on both sides of the radial openings, which is larger than the first outer sealing diameter and smaller than the second outer sealing diameter.A control spool (18) is guided axially behind the radial openings on a guide diameter (D4) of the mounting bushing. Such a directional control valve is designed to allow high flow rates in both directions. This is achieved by ensuring that the ratio between the first outer sealing diameter and the guide diameter for the control spool is between 1.10 and 1.22. Accordingly, the mounting bushing is characterized by a particularly large inner diameter, which enables high flow rates.