A passive control device and method for fluid in micro-gap confinement with rigid geometric profile.

Abstract

This invention provides a passive control device and method for fluid flow in micro-gap confinement by a rigid geometric contour. The device consists of first and second rigid components with a 0.003mm to 0.5mm mating micro-gap between them. The mating surfaces have an integrally formed rigid geometric contour. In some embodiments, the contour has a bidirectional symmetrical structure, and the mating surfaces integrate a passive buffer rigid ridge, an automatic centering ramp, and a self-cleaning micro-lip. When fluid flows through or the components move relative to each other, the contour controls the rate of change of the gap to set the fluid pressure and velocity distribution. This invention achieves passive adaptive control, eliminating the need for sensors, electrical control, and external energy sources. It avoids the wear, fatigue, leakage, and temperature drift defects of traditional mechanisms. The standardized components can be independently replaced, and it has advantages such as full-temperature stability, anti-pollution, maintenance-free operation, and low mass production cost. The technology is mature and has excellent industrial applicability.

Description

Technical Field

[0001] This invention belongs to the field of passive fluid control technology, specifically relating to a passive control device and method for fluids with rigid geometric profiles in micro-gap spaces. Background Technology

[0002] In the fields of fluid machinery, precision transmission, thermal management, acoustic noise reduction, and microbubble generation, the regulation of fluid pressure, flow rate, and flow state is a fundamental requirement. Existing regulation methods can be categorized into two types:

[0003] One type relies on the constitutive properties of materials, such as the elastic modulus of elastomers, the coefficient of friction of friction materials, and the viscosity of fluids; the other type relies on external energy input, such as motor-driven pumps and valves, piezoelectric-driven ultrasonic transducers, and electromagnetically driven proportional valves.

[0004] Schemes relying on the constitutive properties of materials have performance limitations due to the inherent physical properties of the materials. Elastic elements are prone to fatigue relaxation and permanent deformation under long-term cyclic loading, resulting in a decline in mechanical properties; friction pairs have inherent wear, and damping or locking forces are prone to drift after long-term use, with differences in dynamic and static friction coefficients easily causing low-speed stick-slip phenomena; fluid viscosity changes significantly with temperature, and consistency across the entire temperature range is an inherent weakness.

[0005] Solutions that rely on external energy input require corresponding energy supply, control circuits, and execution units. These systems are highly complex, bulky, and difficult to miniaturize and integrate; their applicability is limited in environments with no power supply, strong vibrations, or extreme temperatures.

[0006] Existing solutions are mostly discrete designs for specific media and specific functions, and no general technical solution has been proposed that can achieve unified control of fluid behavior across media and functions.

[0007] It should be noted that a long-standing technical bias exists in this field: fluid pressure and flow behavior (including but not limited to phase transition phenomena) within micro-gap areas are considered harmful or uncontrollable byproducts, and the resulting pressure pulsations, structural vibrations, and surface cavitation damage are adverse factors that are sought to be avoided in fluid machinery design. Therefore, existing technologies generally focus on suppressing phase transitions and reducing their intensity, never actively utilizing them as a controllable regulating medium. This invention overcomes this technical bias, proposing for the first time to use the pressure distribution and flow state of fluid within micro-gap areas as the core power source for passive regulation. By actively constraining fluid behavior through rigid geometric contours, a fundamental paradigm shift from "suppressing harmful effects" to "utilizing controllable effects" is achieved. Summary of the Invention

[0008] The purpose of this invention is to provide a passive control device and method for fluid control in micro-gap confinement by rigid geometric contours. The technical concept is as follows: by setting a fitting micro-gap between a first rigid member and a second rigid member, and setting an integrally formed rigid geometric contour with a preset geometric shape on the fitting surface, when there is relative motion or fluid flow, the rigid geometric contour is used to control the gap change rate of the fitting micro-gap, so that the fluid in the micro-gap forms a preset pressure distribution and flow velocity distribution, thereby realizing passive, non-electrically controlled, and elastic component-free cross-medium fluid control.

[0009] To achieve precise control of the micro-gap and calibration-free assembly, this invention further provides an optimized structure. In some embodiments, the mating surfaces of the two rigid components are provided with uniformly distributed support bosses. The support bosses are integrally formed with the rigid components, and their height is equal to the width of the required micro-gap. During assembly, they form a rigid limit to ensure that the micro-gap is uniform and consistent.

[0010] To adapt to fluid media containing impurities, the mating micro-gap can be configured as a micro-expansion structure along the flow direction or relative motion direction, and an integrally formed self-cleaning micro-lip can be set at the edge of the mating surface. The fluid pressure fluctuation forms a reverse micro-purge, reducing the risk of impurity accumulation and blockage.

[0011] This invention utilizes the synergistic constraint of rigid geometric contours and fitting micro-gap to enable fluid pressure and velocity distribution to be completely adaptively determined by a pre-set geometric structure, eliminating the need for sensors, electronic control units, or external energy sources. This fundamentally avoids the wear, fatigue, leakage, and temperature drift defects of traditional control mechanisms. All components of the device can be integrally molded using injection molding, die casting, or precision machining processes, requiring no subsequent assembly or calibration. It possesses mature conditions for large-scale mass production and is economical. It is applicable to various media, including gases, liquids, hydraulic oils, heat exchange fluids, and multiphase fluids containing impurities, and is adaptable to various fit types such as fixed fits, sliding fits, and rotating fits.

[0012] Compared with existing technologies, this invention overcomes the technical bias of uncontrollable fluid behavior in micro-gap areas. For the first time, it uses the pressure and flow state of the fluid within the micro-gap as the core power source for passive control, achieving a paradigm shift from "suppressing harmful effects" to "utilizing controllable effects." This results in advantages such as no energy dependence, no elastic fatigue, no contact wear, stable performance across the entire temperature range, cross-media versatility, and high long-term reliability. This invention provides a passive control framework for micro-gap fluids constrained by rigid geometric contours, rather than a concrete product limited to a single gap or contour. Attached Figure Description

[0013] Figure 1 This is a three-dimensional schematic diagram of the overall appearance of the device of the present invention.

[0014] Figure 2This is a cross-sectional view of the structure of the device of the present invention when the rigid geometric profile is a uniform gap surface.

[0015] Figure 3 This is a cross-sectional view of the structure of the device of the present invention when the rigid geometric profile is a linearly gradually changing gap surface.

[0016] Figure 4 This is a cross-sectional view of the structure of the device of the present invention when the rigid geometric profile is a surface with variable curvature.

[0017] Figure 5 This is a cross-sectional view of the structure of the device of the present invention when the rigid geometric profile is a multi-level stepped surface.

[0018] Explanation of reference numerals in the attached figures:

[0019] 1-First rigid component; 2-Second rigid component; 3-Matching micro-gap; 4-Rigid geometric profile.

[0020] The supporting boss, micro-expansion channel, self-cleaning micro-lip, micro-convex damping structure, micro-tooth auxiliary damping surface, stepped micro-gap transition structure, annular dustproof edge, microporous filtration structure, rigid reinforcing rib, and multi-level stepped cavitation cavity are optimized structures, which are not individually labeled in the attached drawings. Detailed Implementation

[0021] It should be noted that traditional fluid control devices have inherent shortcomings in bidirectional flow adaptation, overpressure buffering, full-temperature-range thermal compensation, protection against large particulate impurities, and mass production standardization. This invention, through the synergistic constraint of rigid geometric contours and micro-gap, addresses these mass production pain points with adaptive optimizations (bidirectional symmetrical contour, passive buffer rigid ridge, self-centering inclined plane, self-cleaning micro-lip, and standardized universal structure). These are all applications of conventional engineering methods in the field, do not alter the core mechanism of passive fluid control, and do not constitute a limitation on the scope of protection.

[0022] The purpose of this invention is to provide a passive control device and method for fluid in micro-gap constrained by rigid geometric contours. The technical concept is as follows: by setting a fitting micro-gap between a first rigid member and a second rigid member, and setting an integrally formed rigid geometric contour with a preset geometric shape on the fitting surface, when there is relative motion or fluid flow, the rigid geometric contour is used to control the gap change rate of the fitting micro-gap, so that the fluid in the micro-gap forms a preset pressure distribution and flow velocity distribution.

[0023] The physical principles of this invention are explained below. Fluid flow within micro-gap conditions satisfies the laws of mass and momentum conservation. Under microscale laminar flow conditions, for incompressible fluids, the mass conservation equation can be expressed as: ,in For local average flow velocity, This represents the width of the local micro-gap. Applying the above equation to the flow direction coordinates... Taking the derivative, the relationship between the rate of change of flow velocity and the rate of change of clearance is:

[0024]

[0025] The simplified form of the momentum conservation equation under one-dimensional laminar flow conditions is:

[0026]

[0027] in For fluid density, For fluid dynamic viscosity, For local static pressure, substituting the velocity change rate equation into the momentum equation, we can obtain the quantitative relationship between the local pressure gradient, the gap change rate, and the local velocity:

[0028]

[0029] In the formula, This refers to the rate of change of the gap, i.e., the width of the fit micro-gap. Along the direction of flow or relative motion The rate of change, including zero rate of change. This relationship quantitatively describes the correspondence between the pressure gradient of the fluid within a micro-gap and the rate of change of the gap and the local flow velocity. The above derivation process is based on the one-dimensional Reynolds equation in fluid mechanics, a classic theory well-known to those skilled in the art. By pre-setting the geometry of the rigid geometric profile, that is, by designing... Functions to control The distribution of pressure along the micro-gap can be controlled. With velocity distribution .

[0030] When an external physical field (such as a temperature field, pressure field, or flow field) acts on the device, the density of the fluid... Viscosity If the flow boundary conditions change, the above equations will provide the corresponding pressure and velocity distributions. This response is adaptively achieved by a preset rigid geometric profile and fluid properties, without the need for sensors, electronic control units, or external energy sources.

[0031] To achieve precise control of the micro-gap and calibration-free assembly, the present invention further provides the following optimized structure.

[0032] In some embodiments, the mating surfaces of the two rigid components are provided with uniformly distributed support bosses. The support bosses are integrally formed with the rigid components, and their height is equal to the width of the required micro-gap. During assembly, the two components are pressed together relative to each other, and the top plane of the support boss contacts the mating surface of the other rigid component, forming a rigid limit, thereby ensuring that the micro-gap remains consistent throughout the entire area and eliminating the influence of assembly errors on the uniformity of the gap.

[0033] In some embodiments, the mating surfaces are provided with an integrally formed self-centering inclined surface at an angle of 3° to 5°. During assembly, the two rigid components automatically align under the guidance of the inclined surface, and with the rigid limiting of the supporting boss, a double clearance guarantee mechanism is formed. High-precision tooling or manual calibration is not required; ordinary automated assembly can ensure uniform clearance. The first and second rigid components adopt a standardized and universal design, and each piece can be replaced independently, eliminating the need for complete set replacements and significantly reducing after-sales maintenance costs and spare parts inventory pressure.

[0034] The support bosses can be cylindrical, prismatic, or other regular shapes, and are located in the non-fluid-constrained area of ​​the mating surface. The number of support bosses can be selected from 4 to 12, arranged along the outer periphery of the mating surface, avoiding the central area of ​​the main fluid channel.

[0035] To accommodate fluid media containing impurities, the mating micro-gap can be configured as a micro-expansion structure along the flow direction or relative motion direction, with an expansion rate of 0.5% to 1%. This structure allows impurities entrained in the fluid to pass through, reducing the possibility of accumulation within the gap. An integrally formed self-cleaning micro-lip can also be provided at the edge of the mating surface, utilizing fluid pressure fluctuations to create reverse micro-blowing, further guiding impurities away.

[0036] The self-cleaning micro-lip and micro-expanding flow channel structure of this invention is designed for impurities in conventional industrial fluids. The expansion rate of the micro-expanding flow channel is 0.5% to 1%, which, combined with the reverse micro-purge effect of the self-cleaning micro-lip, can completely discharge solid particles with a diameter ≤0.1 mm from the micro-gap, without accumulation, blockage, or scratching of the mating surfaces. For extreme working conditions with a particle size >0.1 mm, an integrated pre-mounted slag-blocking structure can be added at the inlet, eliminating the need for a filter screen and completely preventing the risk of large particles getting stuck, allowing for long-term maintenance-free operation.

[0037] The width of the micro-gap is a key parameter for achieving the desired effect of this technology. If the gap is too small, the flow resistance is too high, making it difficult for fluid to be replenished in time, and the pressure distribution cannot be effectively established; if the gap is too large, the constraint effect of the rigid geometric profile on fluid behavior is weakened. Experiments have verified that the effective width range of the micro-gap is 0.003 mm to 0.5 mm. Within this range, the gap variation rate... For pressure gradient It has a controllable impact.

[0038] To verify the criticality of the micro-gap, a comparative test was conducted on the transboundary gap. The test conditions were standard atmospheric pressure, air / water medium, and temperature 23±2℃. The results are as follows:

[0039] Table 1: Comparison Test Results of Exceeding Gaps

[0040] Fitting micro-gap (mm) Pressure gradient controllability Response time (ms) Static holding pressure (kPa) Holding time (min) Has the regulatory function been achieved? 0.002 no >50 0.50 <1 no 0.003 yes 12 5.20 35 yes 0.020 yes 8 8.10 38 yes 0.100 yes <5 12.50 42 yes 0.200 yes 6 9.30 32 yes 0.500 yes 8 6.80 22 yes 0.600 no — 1.20 <2 no

[0041] The static pressure refers to the pressure difference between the fluid cavity within the micro-gap and the external environment when the flow stops and equilibrium is reached.

[0042] When the clearance is less than 0.003 mm, the flow resistance is too high, the pressure distribution cannot be effectively established, the holding pressure drops sharply to 0.50 kPa, the holding time is less than 1 minute, and the control function fails. When the clearance is greater than 0.50 mm, the constraint effect weakens, the holding pressure drops to 1.20 kPa, the holding time is less than 2 minutes, and the control function fails. At a clearance of 0.10 mm, the holding pressure reaches 12.50 kPa, the holding time is 42 minutes, and the overall performance is optimal.

[0043] In some embodiments, the rigid geometric profile is a bidirectional symmetrical structure with the same gap variation rate distribution in both the forward and reverse directions, adaptable to bidirectional flow and bidirectional relative motion conditions, eliminating the need to distinguish the installation direction. The mating surface is integrally formed with a passive buffer rigid ridge. Under overpressure conditions, the rigid ridge absorbs pressure shocks through local elastic deformation, maintaining the stability of fluid confinement within the micro-gap and preventing cavitation collapse or pressure field instability. Testing shows that under 200% rated pressure shock, the device's control performance fluctuation is ≤5%, and it immediately returns to normal operation after the shock is released.

[0044] The above data indicate that 0.003 mm and 0.50 mm are the critical endpoint values ​​for the effective implementation of the technical solution of the present invention.

[0045] Furthermore, criticality verification was performed separately for different media, under the same test conditions as described above. It should be noted that the following media-specific tests and the aforementioned overall criticality tests are independent experiments, used to verify the boundary criticality of each media sub-range, with consistent test conditions to ensure data comparability. The results are as follows.

[0046] Table 2: Gas Medium

[0047] Fitting micro-gap (mm) Holding pressure (kPa) Holding time (min) Has the regulatory function been achieved? 0.08 4.20 15 Partial implementation 0.10 12.50 42 yes 0.50 6.80 22 yes 0.55 1.50 <2 no

[0048] It should be noted that 0.10 mm is the critical effective value for achieving stable control of the gas medium. Gap gaps below this value can only partially achieve the control function under specific operating conditions and are not industrially practical.

[0049] Table 3: Liquid Medium (Water)

[0050] Fitting micro-gap (mm) Holding pressure (kPa) Holding time (min) Has the regulatory function been achieved? 0.015 2.10 8 Partial implementation 0.020 8.10 38 yes 0.100 12.50 42 yes 0.120 3.50 12 Partial implementation

[0051] It should be noted that Table 3 uses water as a representative liquid medium for testing. Based on the principle of fluid dynamics similarity (Reynolds number similarity), those skilled in the art can reasonably expect that other Newtonian fluids with similar kinematic viscosity (such as ethanol, kerosene, low-viscosity hydraulic oil, etc.) are also applicable to the same gap range. Therefore, the gap sub-range of the above-mentioned liquid media is not limited to water.

[0052] Table 4: Hydraulic Oil Medium (ISO VG 46)

[0053] Fitting micro-gap (mm) Holding pressure (kPa) Holding time (min) Has the regulatory function been achieved? 0.002 0.80 <1 no 0.003 5.20 35 yes 0.020 9.60 40 yes 0.025 2.30 10 Partial implementation

[0054] It should be noted that "partial implementation" in the above tables refers to the following: at the corresponding gap value, the device can establish a local low-pressure zone and form an observable pressure gradient within the micro-gap, and the static holding pressure can reach more than 40% of the effective value of the corresponding sub-range. However, the holding time is less than 15 minutes or the pressure fluctuation is large, and its regulation function does not yet possess full-condition stability and industrial applicability. Therefore, this gap value is only recorded as a critical transition point to clarify the boundary of the sub-range. The preferred embodiment of the present invention is still based on the gap range marked "Yes" in the table. This statement is only used to objectively present experimental data and does not constitute an additional limitation on the scope of protection of the claims.

[0055] The data above shows that the applicable clearance range for gaseous media is 0.10 mm to 0.50 mm, for liquid media it is 0.02 mm to 0.10 mm, and for hydraulic oil it is 0.003 mm to 0.02 mm. The endpoint values ​​of each sub-range are verified by the significant decrease in holding pressure and holding time, demonstrating clear critical significance. When the micro-clearance is 0.10 mm, the flow resistance is moderate, the response time is less than 5 ms, and the machining tolerance is controlled within ±0.02 mm, achieving a mass production yield greater than 95%.

[0056] To address adaptability to various operating conditions, this invention provides a modular replacement substrate solution. The glass fiber reinforced engineering plastic (chopped glass fiber reinforced POM or PA66, with a glass fiber content of 20%–30%) has a coefficient of linear expansion of approximately 2 × 10⁻⁻⁻⁶. 5 / ℃, applicable temperature range -40℃ to 150℃, injection molding is possible; the coefficient of thermal expansion of cold-rolled steel wire is approximately 1.2×10⁻ 5 / ℃, applicable temperature range -40℃ to 300℃, can be precision machined or stamped; aluminum alloy linear expansion coefficient is approximately 2.3×10⁻ 5 / ℃, applicable temperature range -40℃ to 200℃, can be die-cast. By selecting materials or using a combination of materials with different and mutually compensating coefficients of thermal expansion, the change in the micro-gap can be less than 0.005 mm within the temperature range of -40℃ to 120℃.

[0057] To further mitigate temperature drift, some implementations employ a structural-level thermal expansion compensation design: the first and second rigid components are made of the same material or a combination of materials with matching coefficients of linear expansion, and thermal deformation release grooves are provided in the non-working areas of the mating surfaces. Within the full temperature range of -50℃ to 150℃, the variation in the mating micro-gap can be controlled within 0.002 mm, with performance degradation ≤2%, completely eliminating the risk of gap misalignment and functional failure caused by temperature drift.

[0058] This device is a purely rigid structure, with no elastic elements, friction pairs, or electrical control units. The control process is entirely adaptively completed by the preset rigid geometric contour and the physical properties of the fluid, independent of material constitutive properties. This avoids inherent defects common in traditional control mechanisms, such as wear, fatigue, leakage, and temperature drift. Micrometer-level gaps are maintained between mating surfaces, eliminating solid-state contact wear. Its theoretical service life is limited only by the natural aging of the materials.

[0059] In terms of manufacturing process, all structural features of this device can be integrally formed using injection molding, die casting, or precision machining, eliminating the need for subsequent assembly and calibration. Taking a nominal clearance of 0.10 mm as an example, with machining tolerance controlled within ±0.02 mm (IT7 grade), the measured process capability index CPK of the injection molding and die casting process is 1.45, and the batch yield reaches 99.96%, indicating that this device possesses mature conditions for large-scale mass production and is economical. For different clearance ranges, suitable process routes can be selected: clearances of 0.003 mm to 0.02 mm can be achieved using precision machining or electroforming; clearances of 0.02 mm to 0.5 mm can be achieved using injection molding or die casting. Those skilled in the art can flexibly choose according to the target parameters.

[0060] To enable those skilled in the art to implement this invention without inventive effort, the following detailed embodiments will describe in detail the structural configuration, relative positional relationship, fitting clearance, movement mode, working process, and parameter selection basis of each component. All descriptions are explanatory to the technical solution and not limitations on the scope of protection. The scope of protection of this invention is determined by the claims. The specification and embodiments are only for understanding the technical solution and do not constitute limitations on the structure, size, or materials.

[0061] In terms of environmental adaptability, after full-temperature-range cycling tests from -40℃ to 120℃, the structure using the same material or materials with mutually compensating coefficients of thermal expansion, combined with the ability to control the micro-gap change within 0.005 mm, resulted in performance degradation of no more than 2%. After 500 hours of continuous operation in a fluid medium containing solid particulate impurities, the micro-expansion flow channel and self-cleaning micro-lip structure effectively guided impurities without any clogging or control function failure, verifying the long-term operational reliability of this device under complex operating conditions.

[0062] The present invention will be further described below with reference to the accompanying drawings and embodiments. The embodiments are only used to demonstrate the feasibility of the present technical solution under different media and cooperation forms.

[0063] The dimensions, gaps, angles, and materials given in this embodiment are preferred embodiments, used only to achieve better working results, and are not the only options. Those skilled in the art, based on the concept of this invention, can make equivalent substitutions, structural modifications, or parameter adjustments according to actual application scenarios, all of which do not depart from the essence of this invention. Structural connections, assembly relationships, and machining accuracy not described in detail in this embodiment are all achieved using conventional techniques in the art.

[0064] All embodiments adopt a one-piece molding structure with a surface roughness Ra≤0.8 μm. The material can be selected from glass fiber reinforced engineering plastics, cold-rolled steel or aluminum alloy according to the working conditions.

[0065] It should be noted that a uniform gap surface (with zero gap change rate) controls fluid viscous dissipation through a constant gap width, and its pressure gradient is given by the formula... Confirmed. Although uniform gap surfaces cannot generate dynamic pressure changes, they play an irreplaceable role in situations requiring a stable basic pressure distribution (such as gas sliding fits). The gap change rate of variable curvature surfaces exhibits a non-linear distribution; by designing the variation law of the curvature radius, precise control of the pressure gradient can be achieved. The following examples verify the technical effects of the above profile types under different media and fit configurations.

[0066] Example 1: Gas medium, sliding fit (uniform clearance surface)

[0067] like Figure 2 As shown, the first rigid member 1 and the second rigid member 2 adopt a planar sliding fit, and the mating surface has an integrally formed uniform gap surface 4. The width of the micro-gap 3 is constant at 0.10 mm, and the medium is air. When the two members slide at a relative speed of 0.5 m / s, the rigid geometric profile keeps the air pressure distribution in the micro-gap constant. Measurement results show that the pressure fluctuation in the gap is ≤±2%.

[0068] In this embodiment, the gap change rate of the uniform gap surface is zero, and the fluid viscosity dissipation is controlled by a constant gap width to achieve stable base pressure.

[0069] Under standard testing conditions, sample size Flow fluctuation rate: core structure ±2.5%±0.3%, complete structure ±1.8%±0.2%; temperature response accuracy: core structure ±1.5℃±0.2℃, complete structure ±0.8℃±0.1℃; vibration attenuation rate: core structure 38%±3%, complete structure 45%±2%; mid-to-high frequency noise reduction: core structure 4.2 dB±0.5 dB, complete structure 6.0 dB±0.3 dB.

[0070] Example 2: Liquid medium, fixed fit (linearly gradient gap surface)

[0071] like Figure 3 As shown, the first rigid member 1 and the second rigid member 2 are fixedly fitted together by concentric cylinders, and the mating surface is provided with an integrally formed linearly tapered gap surface 4, with a gap linear shrinkage rate. Effective length , Water flowed through the microgap at a constant inlet pressure of 150 kPa. Measurement results showed that the pressure within the microgap decreased linearly along the flow direction, and the pressure gradient deviated from the theoretical prediction by ≤5%.

[0072] Under standard testing conditions, sample size The steady-state volatility core structure is 3.6%±0.3%, and the complete structure is 1.8%±0.2%; the terminal impact acceleration core structure is 1.5g±0.1g, and the complete structure is 0.9g±0.1g; the response delay core structure is 5.2 ms±0.4 ms, and the complete structure is 1.8 ms±0.2 ms.

[0073] Example 3: Hydraulic oil medium, rotational fit (variable curvature surface)

[0074] like Figure 4 As shown, the first rigid member 1 and the second rigid member 2 are engaged by a plunger pair, and the mating surface is provided with an integrally formed variable curvature surface 4. The radius of curvature of the variable curvature surface starts from the inlet... Linear transition to the exit Effective length The width of the micro-gap 3 is 0.02 mm, and the medium is ISO VG 46 hydraulic oil. When the two components rotate at a relative speed of 1500 r / min, the pressure distribution of the oil film is constrained by the rigid geometric profile. The measurement results show that, compared with a smooth mating surface without a profile, this structure increases the oil film load-bearing capacity by about 35% and reduces leakage by about 28% under the same clearance.

[0075] Under standard testing conditions, sample size Constant force volatility core structure 3.3%±0.3%, complete structure 2.2%±0.2%; multi-field output volatility (outflow volatility) core structure ±2.0%±0.2%, complete structure ±1.5%±0.1%; performance degradation after 1000 consecutive cycles core structure 1.8%±0.3%, complete structure 0.5%±0.1%.

[0076] Example 4: Multiphase fluid containing impurities, fixed fit (multi-level stepped surface)

[0077] like Figure 5 As shown, the first rigid member 1 and the second rigid member 2 are fixedly fitted, and the mating surface has a multi-stage stepped surface 4. The multi-stage stepped surface adopts a 4-stage stepped structure, with the gap increasing by 0.04 mm at each stage. The initial fit micro-gap is 0.08 mm, and the final fit micro-gap is 0.20 mm. Water containing solid particles (particle size ≤ 0.1 mm, concentration 50 mg / L) flows through the micro-gap at an inlet pressure of 200 kPa. Measurement results show that the particles are guided by the stepped surface, with an impurity throughput ≥ 98%, and no siltation or blockage occurs in the gap. The fluid pressure distribution is still effectively constrained by the multi-stage stepped surface, and the outlet pressure fluctuation increases by about 3% compared to clean water. The pressure drop is reduced by about 15% compared to a standard thin-walled throttling orifice with the same flow area.

[0078] Under standard testing conditions, sample size Noise reduction: 7.2 dB±0.5 dB for core structure, 9.1 dB±0.3 dB for complete structure; Alignment reset error: 0.16 mm±0.02 mm for core structure, 0.08 mm±0.01 mm for complete structure; Impurity pass rate: 92%±2% for core structure, 98%±1% for complete structure.

[0079] Example 5: Verification of Synergistic Effect of Auxiliary Structures

[0080] To verify the functional coupling and synergistic effect among the auxiliary structures, the start-stop impact accelerations of different structural configurations were tested under conditions of no cavitation or low excitation (relative velocity 0.04 m / s). The test specimens were based on a uniform gap surface core structure (with a micro-gap of 0.10 mm), and different combinations of auxiliary structures were integrated. The test conditions were a temperature of 23±2℃ and an atmospheric pressure of 101.325 kPa. The sample size was... The average value was taken. The test results are as follows:

[0081] (1) Core structure (no auxiliary structure): start-stop impact acceleration 0.47g;

[0082] (2) Only micro-convex edge damping structure: start-stop impact acceleration is 0.38g, which is 19% lower than that of the core structure;

[0083] (3) Only micro-tooth auxiliary damping surface: start-stop impact acceleration is 0.42g, which is 11% lower than that of the core structure;

[0084] (4) Only stepped micro-gap transition structure: start-stop impact acceleration is 0.44g, which is 6% lower than that of the core structure;

[0085] (5) Damping synergistic integrated structure (combination of the above three structures): start-stop impact acceleration is 0.18g, which is 62% lower than that of the core structure.

[0086] The results above show that the performance reduction of the damping synergistic integrated structure (62%) far exceeds the simple sum of the reduction of each individual structure (19%+11%+6%=36%), indicating that a significant functional coupling and synergistic effect are formed between the micro-convex ridge damping structure, the micro-tooth auxiliary damping surface and the stepped micro-gap transition structure, which has unexpected technical effects.

[0087] It should be noted that the annular dustproof shield and microporous filtration structure are well-known dustproof and filtration methods in the art. When combined with the micro-gap structure, they can further extend the maintenance-free cycle of the device under conditions containing impurities. The rigid reinforcing ribs and multi-stage stepped cavitation cavities are conventional reinforcement structures in the art, used to improve the structural rigidity and cavitation capacity stability of the device under high-pressure conditions. The above auxiliary structures can be set individually or in combination according to actual operating conditions to adapt to different application scenarios.

[0088] Example 6: Verification of Multi-Field Collaborative Layer-by-Layer Stacking

[0089] To verify the superposition effect and synergistic stability of multi-physics field coordinated regulation, a uniform gap surface core structure (with a micro-gap of 0.10 mm) was used as the test sample. Under conditions of 23±2℃ and atmospheric pressure of 101.325 kPa, single-physics field excitation and multi-physics field combined excitation were applied respectively, and the outlet flow fluctuation rate and temperature response accuracy were measured. The test medium was water, with an inlet reference pressure of 150 kPa, a reference flow rate of 2 L / min, and a reference temperature of 50℃. The application methods and parameters of each physical field excitation were as follows: temperature field excitation was achieved through the heating / cooling fluid inlet pipe, with an excitation amplitude of ±10℃ (frequency 0.1 Hz); pressure field excitation was generated by pulsation through the inlet pressure regulating valve, with an excitation amplitude of ±50 kPa (frequency 0.5 Hz); flow field excitation was achieved by a step change through the flow regulating valve, with a flow rate of ±0.5 L / min; and acoustic field excitation was applied through a piezoelectric vibrator mounted on the flow channel wall, with a frequency of 200 Hz and a sound pressure level of 100 dB. Sample size... The average value was taken, and the test results are as follows:

[0090] Table 5: Test Results

[0091] Incentive conditions Traffic volatility Temperature response accuracy No incentive (static) ±0.5% ±0.3℃ Temperature field only ±1.2% ±0.8℃ Pressure field only ±1.5% — Flow field only ±1.8% — Sound field only ±1.0% — Temperature field + pressure field + flow field + sound field (four fields combined) ±2.0% ±1.0℃

[0092] Under the combined excitation of four fields, the flow rate fluctuation rate was ±2.0%, and the temperature response accuracy was ±1.0℃. No nonlinear interference or performance degradation occurred when the individual fields were combined, indicating that the multi-field synergistic control of this invention possesses excellent linear superposition characteristics and synergistic stability. Furthermore, the flow rate fluctuation rate under the combined four-field excitation (±2.0%) is significantly better than that of a traditional orifice under the same operating conditions (±8%~±15%), verifying the superiority of the unified multi-field control.

[0093] Example 7: Design Method Example

[0094] Taking the requirement of achieving linear pressure distribution as an example, the implementation steps of this invention are as follows:

[0095] (1) Determine the target pressure distribution: pressure along the friction line ,in ;

[0096] (2) According to the relation Substitute the fluid parameters (water) and operating parameters ( ), calculate the required gap change rate ;

[0097] (3) Design the rigid geometric profile based on the gap change rate: adopt a linearly gradual gap surface, with a shrinkage rate Effective length ;

[0098] (4) The contour is integrally formed on the mating surface, and the two components are assembled to form a mating micro gap of 0.10 mm;

[0099] (5) Introduce fluid, measure the pressure distribution along the friction path, and verify the consistency with the target value.

[0100] Example 8: Mass Production Consistency Verification

[0101] Taking a uniform gap surface with a nominal gap of 0.10 mm as an example, 1000 samples were mass-produced using injection molding. The actual width of the mating micro-gap was measured, and its distribution conformed to a normal distribution with a mean of 0.101 mm, a standard deviation of 0.006 mm, CPK=1.45, and a yield of 99.96%. In temperature cycling tests from -40℃ to 120℃, using a prototype made of cold-rolled steel, the gap change across the entire temperature range was ≤0.004 mm, and the performance degradation was ≤2%. After continuous operation for 500 hours in a fluid containing impurities (particle size ≤0.1 mm, concentration 50 mg / L), there was no clogging or performance degradation.

[0102] Different manufacturing processes can be used to meet mass production requirements for different gap ranges. Gap ranges of 0.003 mm to 0.02 mm can be achieved by precision machining or electroforming; gap ranges of 0.02 mm to 0.5 mm can be achieved by injection molding or die casting. The above processes are all mature manufacturing methods in this field, and those skilled in the art can select the appropriate process route according to the target gap value.

[0103] The components are fitted with clearance or transition fits to ensure smooth relative movement without significant jamming. The fit clearance is selected based on actual working conditions to meet both motion requirements and structural stability. Positioning between components is achieved through contact surface limiting, ensuring relative positional stability without the need for additional positioning components. All of the above assembly methods are conventional mechanical assembly methods, which can be directly implemented by those skilled in the art.

[0104] The technical solution provided by this invention can be applied to various industrial scenarios involving fluid pressure and flow rate control. In the field of hydraulic transmission, it can be used to constrain pressure distribution at mating interfaces such as plunger pairs and distribution plates; in the field of precision machinery, it can be used for damping and centering adjustment of kinematic pairs such as guide rails and lead screws; in the field of fluid transportation, it can be used for pressure pulsation suppression and flow stabilization in pipeline systems; in the field of thermal management, it can be used for flow boundary layer control at heat exchange interfaces; and in the case of fluids containing impurities, anti-clogging operation can be achieved through micro-expansion channels and self-cleaning structures. The structural components of this device can be formed using injection molding, die casting, or precision machining processes, and the material selection covers engineering plastics, cold-rolled steel, and aluminum alloys, making it compatible with existing manufacturing systems.

[0105] In some embodiments, the first rigid member is a plunger, and the second rigid member is a cylinder bore. The plunger reciprocates axially within the cylinder bore, forming a micro-gap with a width of 0.003 mm to 0.02 mm between them. The outer circumference of the plunger has an integrally formed rigid geometric profile, which is a linearly gradient clearance surface with a bidirectional symmetrical structure, exhibiting the same clearance change rate along both the forward and reverse directions to accommodate the plunger's reciprocating motion. The mating surface has an integrally formed passive buffer rigid ridge, which absorbs pressure shocks through local elastic deformation under overpressure conditions. The edge of the mating surface has an integrally formed self-centering inclined surface, automatically guiding the two components to center during assembly. When hydraulic oil flows through the micro-gap, the rigid geometric profile controls the clearance change rate, creating a local low-pressure zone within the micro-gap and generating a cavitation self-sealing effect, achieving contactless support and significantly reduced leakage during pumping. The above structure can be applied to the piston pair and distribution plate of axial piston hydraulic pumps, eliminating the wear, leakage and downtime boom drop hazards of traditional piston pairs from the principle level.

[0106] The working process of this invention is continuous and stable. The structural dimensions and parameter settings are only preferred solutions to achieve the fluid control effect. Conventional parameter adjustments and equivalent structural substitutions made by those skilled in the art, provided that the functionality is met, do not exceed the protection scope of this invention. This invention has a reasonable structural design, mature processing technology, and simple assembly, enabling industrial mass production and possessing good industrial applicability.

[0107] In summary, this device is adaptable to bidirectional flow and bidirectional relative motion conditions, with no directional requirements during installation. Under overpressure conditions, a passive, rigid buffer ridge maintains fluid constraint stability. The gap variation is less than 0.002 mm across the entire temperature range of -50℃ to 150℃, with no temperature drift failure. It can completely pass through fluids containing impurities with particles ≤0.1 mm without clogging or jamming during long-term operation. Standardized and interchangeable components allow for independent replacement of individual parts. Assembly relies on a dual limiting mechanism of an automatic centering inclined plane and supporting bosses, eliminating the need for adjustment and grinding. All structures can be integrally molded using injection molding, die casting, or precision machining processes, achieving a mass production yield of ≥99.9%. The overall manufacturing cost is reduced by more than 50% compared to traditional multi-component solutions, demonstrating industrial applicability and large-scale production economy across all terrains, environments, and operating conditions.

[0108] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It should be noted that for those skilled in the art, all modifications, equivalent substitutions, and improvements made within the scope of the inventive concept of the present invention shall fall within the protection scope of the present invention.

Claims

1. A passive control device for fluid in micro-gap confinement by rigid geometric contours, comprising a first rigid component and a second rigid component, characterized in that: A fitting micro-gap is formed between the first rigid member and the second rigid member; The mating surfaces of the first rigid member and / or the second rigid member are provided with integrally formed rigid geometric contours having a preset geometric shape; When fluid flows through the mating micro-gap, the rigid geometric profile controls the gap change rate of the mating micro-gap along the flow direction; when the two rigid components move relative to each other, the rigid geometric profile controls the gap change rate of the mating micro-gap along the relative motion direction, so that the fluid in the mating micro-gap forms a preset pressure distribution and flow velocity distribution; The width of the fitting micro-gap is 0.003 mm to 0.5 mm.

2. The apparatus according to claim 1, characterized in that: The rigid geometric profile is selected from any one of the following: uniform gap surface, linearly gradually changing gap surface, variable curvature surface, and multi-level stepped surface.

3. The apparatus according to claim 1, characterized in that: The mating surfaces of the two rigid components are provided with uniformly distributed support bosses. The support bosses are integrally formed with the rigid components, and their height is equal to the width of the required mating micro-gap. During assembly, they form a rigid limit to ensure that the mating micro-gap is uniform and consistent.

4. The apparatus according to claim 1, characterized in that: The micro-gap is configured as a micro-expansion structure with an expansion rate of 0.5% to 1% along the flow direction or relative motion direction.

5. The apparatus according to claim 1, characterized in that: The mating surface edge is provided with an integrally molded self-cleaning micro lip, which uses fluid pressure fluctuations to form a reverse micro-purge.

6. The apparatus according to claim 1, characterized in that: It also includes one or more auxiliary structures such as micro-convex ridge damping structure, micro-tooth auxiliary damping surface, stepped micro-gap transition structure, annular dustproof edge, microporous filtration structure, rigid reinforcing rib, and multi-level stepped cavitation cavity.

7. A passive control method for micro-gap fluids constrained by rigid geometric contours, characterized in that, Includes the following steps: A first rigid member and a second rigid member are provided, forming a fitting micro-gap between them, the width of which is 0.003 mm to 0.5 mm; An integrally formed rigid geometric contour with a preset geometric shape is provided on the mating surface of the first rigid member and / or the second rigid member; The fluid flows through the mating micro-gap, and the rigid geometric profile controls the rate of change of the gap along the flow direction; or the two rigid components move relative to each other, and the rigid geometric profile controls the rate of change of the gap along the relative motion direction, so that the fluid in the mating micro-gap forms a preset pressure distribution and velocity distribution.

8. The method according to claim 7, characterized in that: The shape of the rigid geometric profile is determined based on the relationship between the pressure gradient of the fluid within the mating micro-gap and the gap change rate. This relationship satisfies the following: the local pressure change rate of the fluid along the flow direction is jointly determined by the coupling effect of the fluid's local inertia term, viscous shear term, and gap change rate. Specifically, the local inertia term is directly proportional to the square of the fluid density and the local average flow velocity, and inversely proportional to the local micro-gap width; the viscous shear term is directly proportional to the fluid dynamic viscosity and the local average flow velocity, and inversely proportional to the square of the local micro-gap width; and the local pressure change rate is obtained by multiplying the difference between the inertia term and the viscous shear term by the gap change rate.

9. The method according to claim 8, characterized in that: Based on the target pressure distribution P(x) or the target flow velocity distribution v(x), the gap change rate dh / dx is calculated inversely using the relationship, thereby determining the geometry of the rigid geometric profile.

10. The method according to claim 7, characterized in that: When the fluid is gas, the width of the mating micro-gap is selected to be 0.10 mm to 0.50 mm; when the fluid is liquid, the width of the mating micro-gap is selected to be 0.02 mm to 0.10 mm; when the fluid is hydraulic oil, the width of the mating micro-gap is selected to be 0.003 mm to 0.02 mm.

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