Manufacturing method and mechanism of hydraulic actuating mechanism of low-friction sealing structure

Abstract

The invention relates to the technical field of sealing, in particular to a manufacturing method and mechanism of a hydraulic actuating mechanism of a low-friction sealing structure. The method comprises the following steps: determining a first function relationship between oil film pressure between a sealing element of an actuating mechanism semi-finished product and a barrel and the axial position of the barrel; the increasing speed of the oil film pressure in the first function relation is obtained; the first oil film thickness of the axial position, corresponding to the increasing speed, of the barrel is determined; the second oil film thickness of the position with the maximum oil film pressure is determined; determining the thickness of a third oil film on the outer side of a sealing interface between the sealing piece and the barrel; determining the oil volume of a first gap between the sealing element and the protection ring according to the third oil film thickness; determining size parameters of a pressure relief channel according to the oil volume; a pressure relief channel is machined in the outer circumferential wall of the protection ring according to the size parameters; in this way, the problem that friction resistance is too large due to pressure trapping of a hydraulic actuating mechanism which rotates and does reciprocating telescopic motion is solved.

Description

Technical Field

[0001] This invention relates to the field of sealing technology, and more specifically, to a manufacturing method and mechanism for a low-friction sealing structure hydraulic actuation mechanism. Background Technology

[0002] Existing piston sealing systems are equipped with protective rings. These protective rings, along with the seals, piston, and cylinder, constitute the sealing-related structure. The protective rings and seals are arranged sequentially along the axial direction, typically with two protective rings and the seal located between them. The protective rings primarily assist the seals in maintaining sealing stability, but an annular gap forms between the protective rings and the seals due to the ingress of oil. This annular gap is located between the piston and the cylinder. When the hydraulic system pressure changes rapidly, the fluid within this annular gap cannot be discharged in time. With the relative movement of the piston and cylinder, hydraulic oil continuously enters the annular gap, leading to a trapped pressure phenomenon, which is more pronounced in high-speed piston movements. The additional pressure generated by this trapped pressure forces a large oil film pressure between the seals and the cylinder, resulting in a significant increase in friction at the moment of piston start-up. This not only increases system energy loss but also accelerates the wear of the seals and cylinder due to long-term high friction, shortening the service life of the sealing structure.

[0003] While the use of slit protective rings can address the aforementioned issues, the structure of these rings with fixed-angle slits hinders the smooth insertion of the piston into the cylinder, increasing assembly difficulty. Furthermore, under high system pressure, the high pressure can compress the slits of the protective ring, eliminating the pressure relief channel. As the piston moves at high speed, hydraulic oil continuously enters the annular gap, further increasing the pressure within the gap. This pressure further compacts the slits, ultimately leading to the recurrence of pressure trapping, failing to effectively resolve the potential pressure trapping hazard under bidirectional alternating pressure conditions. In addition, in hydraulic actuators where the piston needs to rotate within the cylinder, the slit protective ring is easily squeezed into the sealing gap during rotation, causing structural failure and further increasing the frictional resistance of the hydraulic actuator. Summary of the Invention

[0004] To address the problem of excessive frictional resistance caused by pressure trapping in hydraulic actuation mechanisms for rotational and reciprocating telescopic movements, this invention provides a manufacturing method and mechanism for a low-friction sealing structure hydraulic actuation mechanism.

[0005] In a first aspect, the present invention provides a method for manufacturing a low-friction sealing structure hydraulic actuation mechanism, the method comprising:

[0006] A first functional relationship is determined between the oil film pressure between the seal and the cylinder of the semi-finished actuation mechanism and the axial position of the cylinder; wherein, the semi-finished actuation mechanism includes the cylinder, a piston, the seal, and a protective ring; the piston is slidably disposed in the cylinder; the seal and the protective ring are respectively coaxially fixed with the piston; the seal and the protective ring are slidably fitted against the inner circumferential wall of the cylinder;

[0007] Obtain the growth rate of the oil film pressure in the first functional relationship; wherein the growth rate is greater than 0;

[0008] According to the formula Determine the first oil film thickness at the axial position of the cylinder corresponding to the growth rate; where w A The growth rate; h A η is the thickness of the first oil film; η is the dynamic viscosity of the oil film; v is the moving speed of the piston;

[0009] According to the formula Determine the thickness of the second oil film at the location of maximum oil film pressure; wherein, The thickness of the second oil film;

[0010] According to the formula The thickness of the third oil film on the outer side of the sealing interface between the seal and the cylinder is determined; where h0 is the thickness of the third oil film; k is a proportional value; k < 1;

[0011] The oil volume in the first gap between the seal and the protective ring is determined based on the thickness of the third oil film.

[0012] The size parameters of the pressure relief channel are determined based on the oil volume.

[0013] The pressure relief channel is machined on the outer circumferential wall of the protective ring according to the dimensional parameters; wherein, the pressure relief channel is used to connect the first gap and the second gap; the second gap is located between the outer circumferential wall of the piston and the inner circumferential wall of the cylinder; the second gap is located on the side of the protective ring away from the seal.

[0014] In some embodiments, determining the first functional relationship between the oil film pressure between the seal and the cylinder of the semi-finished actuation mechanism and the axial position of the cylinder includes:

[0015] A macroscopic finite element analysis was performed on the semi-finished actuation mechanism to form a second functional relationship between the contact stress between the seal and the cylinder and the axial position of the cylinder.

[0016] According to the formula A first functional relationship is determined between the oil film pressure between the seal and the cylinder and the axial position of the cylinder; wherein, The oil film pressure; denoted as the contact stress; x represents the axial position of the cylinder.

[0017] In some embodiments, in the case according to the formula Before the step of determining the first oil film thickness at the axial position of the cylinder corresponding to the growth rate, the manufacturing method of the low-friction sealing structure hydraulic actuation mechanism further includes:

[0018] The Reynolds equation for determining the oil film between the seal and the cylinder. Where h(x) is the oil film thickness;

[0019] Differentiating the Reynolds equation yields the following second-order differential equation:

[0020] Where u0 = dv / dx;

[0021] based on The thickness of the first oil film is determined according to the second-order differential equation. .

[0022] In some embodiments, in the case according to the formula Before the step of determining the second oil film thickness at the location of maximum oil film pressure, the manufacturing method of the low-friction sealing structure hydraulic actuation mechanism further includes:

[0023] Based on w A =(dp / dx) A The Reynolds equation and dp / dx=0 determine the thickness of the second oil film as follows: .

[0024] In some embodiments, in the case according to the formula Before the step of determining the thickness of the third oil film on the outer side of the sealing interface between the seal and the cylinder, the manufacturing method of the low-friction sealing structure hydraulic actuation mechanism further includes:

[0025] Obtain the velocity distribution of the oil film at the location with the highest oil film pressure;

[0026] Based on the fact that the flow velocity distribution is linearly varied along the radial direction of the cylinder, k is determined to be 0.4~0.6.

[0027] In some embodiments, the method for manufacturing the low-friction sealing structure hydraulic actuation mechanism further includes:

[0028] Based on the flow velocity distribution, where the flow velocity changes linearly from the outer radial direction to the inner diameter of the cylinder to 0, k=0.5 is determined.

[0029] In some embodiments, determining the oil volume of the first gap between the seal and the protective ring based on the third oil film thickness includes:

[0030] According to the formula The volume of oil per unit length of the first gap between the seal and the protective ring is determined; the unit length is the length along the axial direction of the cylinder; where d is the outer diameter of the seal.

[0031] In some embodiments, the dimensional parameters include cross-sectional area;

[0032] Determining the size parameters of the pressure relief channel based on the oil volume includes:

[0033] Obtain the maximum extrusion gap of the seal;

[0034] The cross-sectional area of ​​the pressure relief channel is determined according to the formula S1≤π(d0 / 2)2; where S1 is the cross-sectional area and d0 is the maximum extrusion gap.

[0035] In some embodiments, the size parameter further includes quantity;

[0036] The step of determining the size parameters of the pressure relief channel based on the oil volume also includes:

[0037] The number of pressure relief channels is determined according to the formula N≥S0 / S1; where N is the number.

[0038] Secondly, the present invention provides a hydraulic actuation mechanism with a low-friction sealing structure, which is manufactured by the manufacturing method of the low-friction sealing structure hydraulic actuation mechanism described in any one of the first aspects;

[0039] The hydraulic actuation mechanism of the low-friction sealing structure includes:

[0040] cylindrical body;

[0041] A piston, which is slidably disposed in the cylinder along the axis of the cylinder; the piston rotates relative to the cylinder;

[0042] A sealing element, the sealing element being annular; the sealing element being coaxially fixed with the piston; the sealing element being slidably fitted against the inner peripheral wall of the cylinder;

[0043] A protective ring is fixed coaxially with the piston; the protective ring slides against the inner circumferential wall of the cylinder; the protective ring and the sealing element are arranged at intervals along the axis of the cylinder; a first gap exists between the protective ring and the sealing element; a second gap exists between the outer circumferential wall of the piston and the inner circumferential wall of the cylinder; the second gap is located on the side of the protective ring away from the sealing element; the outer circumferential wall of the protective ring has a pressure relief channel; the pressure relief channel connects the first gap and the second gap.

[0044] To solve the problem of excessive frictional resistance caused by pressure trapping in hydraulic actuators for rotary and reciprocating telescopic movements, this invention has the following advantages:

[0045] By determining the thickness of the first oil film where the oil film pressure increase is greater than 0, the thickness of the second oil film at the location of maximum oil film pressure is determined from the thickness of the first oil film. The thickness of the third oil film on the outer side of the sealing interface, i.e., the first gap, is then determined from the thickness of the second oil film. The oil volume in the first gap between the seal and the protective ring is then determined based on the thickness of the third oil film. The size parameters of the pressure relief channel are then determined based on this oil volume, and a pressure relief channel connecting the first and second gaps is machined on the outer circumferential wall of the protective ring. This ensures that the size of the pressure relief channel matches the oil volume in the first gap, guaranteeing that the oil in the first gap can smoothly pass through the pressure relief channel to the second gap. It effectively avoids the occurrence of pressure trapping under bidirectional alternating pressure conditions, reduces the oil film pressure between the seal and the cylinder and the frictional force at the moment of piston start-up, reduces system energy loss, slows down the wear of the seal and the cylinder, and improves the service life of the sealing structure. At the same time, it eliminates the need for bevel cuts, improves the ease of assembly between the piston and the cylinder, and can be adapted to actuators that rotate and reciprocate simultaneously, ensuring the structural stability of the protective ring and the seal. Ultimately, it solves the problem of high frictional resistance caused by pressure trapping in existing hydraulic actuators with rotary and reciprocating telescopic movements, meeting the high-performance requirements of aviation hydraulic systems for reliable sealing and low friction of the actuator. Attached Figure Description

[0046] Figure 1 A flowchart illustrating the manufacturing method of the low-friction sealing structure hydraulic actuation mechanism in Embodiment 1 is shown;

[0047] Figure 2 The distribution of contact stress between the seal and the cylinder in Embodiment 1 is shown along the axial direction (x).

[0048] Figure 3 A schematic diagram of the hydraulic actuation mechanism of the low-friction sealing structure in Embodiment 2 is shown.

[0049] Reference numerals: cylinder 10; piston 20; seal 30; protective ring 40. Detailed Implementation

[0050] The present disclosure will now be discussed with reference to several exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and thus implement the present disclosure, and are not intended to imply any limitation on the scope of the disclosure.

[0051] As used herein, the term "comprising" and its variations are to be interpreted as open-ended terms meaning "including but not limited to". The term "based on" is to be interpreted as "at least partially based on". The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment". The term "another embodiment" is to be interpreted as "at least one other embodiment". The terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "vertical", "horizontal", "lateral", "longitudinal", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments and are not intended to limit the indicated devices, elements, or components to having a specific orientation or being constructed and operated in a specific orientation. Furthermore, some of the above terms may be used to indicate other meanings besides orientations or positional relationships; for example, the term "upper" may in some cases indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application according to the specific circumstances. In addition, the terms "installed", "set up", "equipped with", "connected", and "linked" should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, elements, or components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances. Furthermore, the terms "first," "second," etc., are mainly used to distinguish different devices, elements, or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise stated, "a plurality of" means two or more.

[0052] The current structure of the protective ring 40 with a fixed-angle cut hinders the smooth insertion of the piston 20 into the cylinder 10, increasing the difficulty of assembly. Furthermore, under high system pressure, the high pressure will compress the angled cut of the protective ring 40, eliminating the pressure relief channel. As the piston 20 moves at high speed, hydraulic oil continuously enters the annular gap, causing the pressure within the gap to further increase. This pressure will further compact the cut, ultimately leading to the recurrence of pressure trapping, failing to effectively address the potential pressure trapping hazard under bidirectional alternating pressure conditions. In addition, in hydraulic actuation mechanisms where the piston 20 needs to rotate within the cylinder 10, the cut protective ring 40 is easily squeezed into the sealing gap during rotation, causing the protective ring 40 structure to fail and further increasing the frictional resistance of the hydraulic actuation mechanism.

[0053] Example 1:

[0054] In this embodiment, to solve the above problems, the present invention provides a method for manufacturing a low-friction sealing structure hydraulic actuation mechanism, such as... Figure 1 As shown, the manufacturing method of the low-friction sealing structure hydraulic actuation mechanism includes steps S10 to S80, which will be described in detail below:

[0055] Step S10 determines the first functional relationship between the oil film pressure between the seal 30 and the cylinder 10 of the semi-finished actuation mechanism and the axial position of the cylinder 10, providing basic data support for subsequent steps such as obtaining the oil film pressure growth rate and calculating the oil film thickness. The semi-finished actuation mechanism includes the cylinder 10, piston 20, seal 30, and protective ring 40. The piston 20 is slidably disposed within the cylinder 10. The seal 30 and protective ring 40 are coaxially fixed with the piston 20, and the seal 30 and protective ring 40 are slidably attached to the inner circumferential wall of the cylinder 10.

[0056] Step S20: Obtain the growth rate of the oil film pressure in the first functional relationship, accurately capture the dynamic trend of the oil film pressure changing with the axial position of the cylinder 10, and provide key speed parameters for subsequent calculation of the first oil film thickness according to the formula. This ensures that the calculated result of the first oil film thickness can truly reflect the oil film thickness at the pressure growth location, avoiding calculation deviations due to missing parameters. The growth rate must be greater than 0. Figure 2 As shown, point A is the location where the growth rate is greater than 0, and point B is the location where the oil film pressure is the greatest.

[0057] Step S30, according to the formula This determines the first oil film thickness at the axial position of the cylinder 10 corresponding to the growth rate, providing accurate basic data for subsequently deriving the oil film thickness at the position of maximum oil film pressure, ensuring the consistency and accuracy of subsequent oil film thickness calculations. Among these, w A For growth rate; h Aη is the thickness of the first oil film; η is the dynamic viscosity of the oil film; v is the moving speed of piston 20.

[0058] Step S40, according to the formula This method determines the thickness of the second oil film at the location of maximum oil film pressure, accurately pinpoints the oil film state in key areas of the sealing system, and provides a targeted reference for subsequent calculations of the thickness of the third oil film on the outer side of the sealing interface. This is the thickness of the second oil film.

[0059] Step S50, according to the formula The thickness of the third oil film on the outer side of the sealing interface between the seal 30 and the cylinder 10 is determined. Combining the thickness of the second oil film with a proportional value K less than 1, the thickness of the third oil film on the outer side of the sealing interface is determined. This accurately reflects the oil film thickness on the outer side of the critical sealing area. This thickness data is the direct basis for calculating the oil volume of the first gap, ensuring that the subsequent oil volume calculation results match the actual oil distribution at the sealing interface. Where h0 is the thickness of the third oil film; k is the proportional value; k < 1.

[0060] Step S60: Determine the oil volume of the first gap between the seal 30 and the protective ring 40 based on the thickness of the third oil film, and clarify the total amount of oil that needs to be discharged through the pressure relief channel in the gap. This provides a core quantitative basis for determining the size parameters of the pressure relief channel in the future, and avoids the pressure relief channel size not matching the actual drainage requirements due to inaccurate oil volume estimation.

[0061] Step S70: Determine the size parameters of the pressure relief channel based on the oil volume to ensure that the pressure relief channel has a drainage capacity that matches the oil volume. This avoids the oil not being able to drain in time due to the channel size being too small or the structural strength being reduced due to the size being too large, thus laying the parameter basis for processing a pressure relief channel that meets the drainage requirements.

[0062] In step S80, a pressure relief channel is machined on the outer circumferential wall of the protective ring 40 according to the dimensional parameters. This pressure relief channel connects the first gap and the second gap; the second gap is located between the outer circumferential wall of the piston 20 and the inner circumferential wall of the cylinder 10; the second gap is located on the side of the protective ring 40 opposite to the seal 30. By machining a pressure relief channel connecting the first gap and the second gap on the outer circumferential wall of the protective ring 40 according to the dimensional parameters, the oil in the first gap can be smoothly discharged to the second gap, avoiding the risk of pressure trapping that may occur in the piston 20 and seal 30 during high-speed alternating reciprocating motion, reducing the friction of the seal 30, and thus improving the service life of the seal 30. Simultaneously, this pressure relief channel eliminates the need for cuts in the protective ring 40, allowing it to be used in actuators that rotate and reciprocate simultaneously, and also improving the assemblability of the actuator.

[0063] Further, step S10 includes steps S11 and S12. The manufacturing method of the low-friction sealing structure hydraulic actuation mechanism is performed sequentially through steps S11, S12, S20, S30, S40, S50, S60, S70, and S80. Steps S11 and S12 will be described in detail below:

[0064] Step S11 involves performing a macroscopic finite element analysis on the semi-finished actuation mechanism to establish a second functional relationship between the contact stress between the seal 30 and the cylinder 10 and the axial position of the cylinder 10. This macroscopic finite element analysis accurately simulates the contact state between the seal 30 and the cylinder 10, ensuring that the obtained contact stress data truly reflects the stress distribution under actual working conditions, thus providing a reliable basis for determining the subsequent oil film pressure.

[0065] Step S12, as follows Figure 2 As shown, according to the formula This paper establishes a first functional relationship between the oil film pressure between the seal 30 and the cylinder 10 and the axial position of the cylinder 10. The oil film thickness at the sealing interface is very thin and will not cause significant structural deformation to the seal 30. This application equals the oil film pressure to the contact stress between the seal 30 and the cylinder 10 to smoothly calculate the first functional relationship between the oil film pressure and the axial position of the cylinder 10. This avoids the accuracy of subsequent steps such as obtaining the growth rate and calculating the oil film thickness due to deviations in the oil film pressure calculation, thereby ensuring that the subsequently determined pressure relief channel dimensions accurately match the drainage requirements and ultimately help avoid the risk of pressure trapping. Oil film pressure; denoted as contact stress; x represents the axial position of cylinder 10.

[0066] Furthermore, prior to step S30, the manufacturing method of the low-friction sealing structure hydraulic actuation mechanism also includes step S90, which comprises steps S91 to S93. The manufacturing method of the low-friction sealing structure hydraulic actuation mechanism sequentially executes steps S10, S20, S91, S92, S93, S30, S40, S50, S60, 70, and S80. Steps S91 to S93 will be described in detail below:

[0067] Step S91: Determine the Reynolds equation for the oil film between the seal 30 and the cylinder 10. This study establishes a fundamental relationship between oil film thickness, oil film pressure change rate, oil film dynamic viscosity, and piston 20 movement speed. This provides a core theoretical basis for the subsequent derivation of the second-order differential equation and verification of the first oil film thickness calculation formula, ensuring that all subsequent oil film-related calculations conform to the physical laws of oil film flow and avoiding theoretical deviations from actual working conditions. Here, h(x) represents the oil film thickness.

[0068] Step S92, differentiate the Reynolds equation to form a second-order differential equation as follows:

[0069] Where u0 = dv / dx;

[0070] By differentiating the Reynolds equation into a second-order differential equation, the relationship between oil film thickness, the second-order rate of change of oil film pressure, and the rate of change of piston 20 movement speed can be further refined, providing differential equation support for the subsequent derivation of the first oil film thickness calculation formula.

[0071] Step S93, based on The thickness of the first oil film is determined based on the second-order differential equation. This ensures that the first oil film thickness calculated using this formula accurately reflects the oil film state under actual working conditions. It provides a precise formula basis for calculating the second oil film thickness at the location of maximum oil film pressure and the third oil film thickness on the outside of the sealing interface. This ensures that the subsequently determined pressure relief channel size parameters can be adapted to the oil volume of the first gap, effectively draining the oil to avoid the risk of pressure trapping, while maintaining the assembly convenience brought by the 40-inch cut-free design of the protective ring and its adaptability to the side rotation and reciprocating working conditions.

[0072] Furthermore, before step S40, step S90 also includes step S94, in which the manufacturing method of the low-friction sealing structure hydraulic actuation mechanism is performed sequentially through steps S10, S20, S91, S92, S93, S30, S94, S40, S50, S60, S70, and S80. Step S94 will be described in detail below:

[0073] Step S41, based on w A =(dp / dx) A Based on the Reynolds equation and dp / dx=0, the thickness of the second oil film is determined as follows: This process ensures that the calculation results accurately match the actual oil film state at the location of maximum oil film pressure. This avoids calculation errors in the subsequent third oil film thickness and the oil volume in the first gap between the seal 30 and the protective ring 40 due to deviations in the calculation of the second oil film thickness. This ensures that the pressure relief channel size parameters determined based on the oil volume accurately match the drainage requirements, allowing the pressure relief channel to effectively drain the oil in the first gap and avoiding the risk of pressure trapping in the piston 20 and seal 30 during high-speed alternating reciprocating motion.

[0074] Furthermore, prior to step S50, the manufacturing method of the low-friction sealing structure hydraulic actuation mechanism also includes steps S95 and S96. The manufacturing method of the low-friction sealing structure hydraulic actuation mechanism sequentially executes steps S10, S20, S30, S40, S95, S96, S50, S60, S70, and S80. Steps S95 and S96 will be described in detail below:

[0075] Step S95: Obtain the flow velocity distribution of the oil film at the location with the highest oil film pressure. The location with the highest oil film pressure is a key area affecting sealing performance and oil retention. Understanding the flow velocity distribution in this area allows for accurate capture of the actual flow characteristics of the oil film, providing flow data support under real operating conditions for the subsequent determination of the k value, and avoiding setting parameters that deviate from the actual flow state.

[0076] Step S96: Based on the flow velocity distribution, which shows a linear radial change in flow velocity along the cylinder 10, k is determined to be 0.4~0.6. In this embodiment, the oil flow velocity is close to 0 near the seal 30, thus, according to mathematical and geometric relationships, the value of k between 0.4 and 0.6 can accurately reflect the thickness of the third oil film. This range of k values ​​is a reasonable interval derived from the actual flow velocity law of the oil film, ensuring that the subsequently calculated thickness of the third oil film accurately reflects the true oil film thickness outside the sealing interface, avoiding distortion in the calculation of the third oil film thickness due to deviations in the k value; thereby ensuring the accuracy of the oil volume in the first gap between the seal 30 and the protective ring 40 determined based on the thickness of the third oil film, providing a reliable basis for determining the subsequent pressure relief channel size parameters, enabling the pressure relief channel to effectively discharge the oil in the first gap, and avoiding the risk of pressure trapping.

[0077] Furthermore, the manufacturing method of the low-friction sealing structure hydraulic actuation mechanism also includes step S97, which is performed sequentially as follows: S10, S20, S30, S40, S95, S96, S97, S50, S60, S70, and S80. Step S97 can be described in detail below:

[0078] Step S97: Based on the flow velocity distribution, where the flow velocity linearly changes from the outer radial direction to the inner diameter of the cylinder 10 to 0, k is determined to be 0.5. Compared to the previous k values ​​of 0.4~0.6, this further improves the accuracy and specificity of the k value, ensuring that the k value perfectly matches the actual physical state of the oil film under this specific flow velocity distribution; this precise k value ensures that the formula... The calculated thickness of the third oil film more closely matches the actual oil film condition on the outer side of the sealing interface between the seal 30 and the cylinder 10, avoiding deviations in the thickness of the third oil film due to the estimation of the k-value. This ensures the accuracy of the oil volume calculation results for the first gap between the seal 30 and the protective ring 40, based on the thickness of the third oil film, providing a more reliable basis for determining the subsequent pressure relief channel size parameters. This allows the pressure relief channel to more accurately adapt to the oil discharge requirements, effectively avoiding the risk of pressure trapping under bidirectional alternating pressure conditions. At the same time, this step does not change the design of the protective ring 40 without cuts, maintaining the ease of assembly of the actuator and its adaptability to actuators that rotate and reciprocate simultaneously. Furthermore, by precisely controlling the oil film-related parameters, the friction of the seal 30 is further reduced, extending the service life of the seal 30.

[0079] Further, step S60 includes step S61, in which the manufacturing method of the low-friction sealing structure hydraulic actuation mechanism is performed sequentially through steps S10, S20, S30, S40, S50, S61, 70, and S80. Step S61 will be described in detail below:

[0080] Step S61, according to the formula The oil volume per unit length of the first gap between the seal 30 and the protective ring 40 is determined; the unit length is the length along the axial direction of the cylinder 10; where d is the outer diameter of the seal 30. This is achieved by substituting the outer diameter d of the seal 30, the dynamic viscosity η of the oil film, the moving speed v of the piston 20, and the oil film pressure increase rate W. A Once the precise parameters have been determined, then according to the formula... Calculating the oil volume per unit length in the first gap allows for the quantification of the oil volume per unit length within the first gap, using a clearly defined axial length as a benchmark, thus avoiding calculation errors. This oil volume per unit length is the core foundation for subsequent derivation of the overall oil volume in the first gap, ensuring the accuracy of the overall oil volume calculation results. This provides reliable data support for determining the pressure relief channel dimensions based on the oil volume, enabling the pressure relief channel to precisely match the drainage requirements of the first gap and effectively discharge any oil trapped within the gap to avoid the risk of pressure entrapment. Simultaneously, it maintains the ease of assembly of the actuator and its adaptability to actuators that rotate and reciprocate simultaneously. Furthermore, precise control of the oil volume parameters further ensures reduced friction of the seal 30, extending its service life.

[0081] Furthermore, the dimensional parameters include the cross-sectional area;

[0082] Step S70 includes steps S71 and S72, which will be described in detail below:

[0083] Step S71: Obtain the maximum extrusion gap of the seal 30. This gap is the critical size at which the seal 30 may be extruded and deformed under system pressure. It provides a key safety boundary for determining the cross-sectional area of ​​the pressure relief channel, thus avoiding seal failure due to the channel size design deviating from the risk of seal extrusion.

[0084] Step S72: To prevent the seal 30 from being squeezed into the pressure relief channel under high pressure, causing seal failure, the cross-sectional area of ​​the pressure relief channel is determined according to the formula S1≤π(d0 / 2)2; where S1 is the cross-sectional area and d0 is the maximum extrusion gap. Determining the cross-sectional area of ​​the pressure relief channel using this formula ensures that the cross-sectional area matches the previously calculated oil volume in the first gap, meeting the requirement for timely oil discharge, while also strictly controlling the cross-sectional area to not exceed the critical value calculated based on the maximum extrusion gap. This effectively prevents the seal 30 from being squeezed out through the channel under pressure, ensuring the sealing reliability of the sealing structure.

[0085] Furthermore, the dimensional parameters also include quantity;

[0086] Step S70 also includes step S73:

[0087] Step S73: Determine the number of pressure relief channels according to the formula N≥S0 / S1 to ensure the structural strength of the protective ring 40. Here, N is the number of channels; S0 is the oil volume per unit length of the first gap; and S1 is the cross-sectional area of ​​the pressure relief channel. This method ensures that the total drainage area of ​​all pressure relief channels meets the oil drainage requirements of the first gap, preventing insufficient channels from causing the total drainage capacity to be lower than the oil production volume, thus avoiding oil stagnation and pressure trapping. Furthermore, this method of determining the number of channels, based on the previously accurately calculated S0 and S1, allows for a reasonable configuration of the number of channels, avoiding both excessive channels that reduce the structural strength of the protective ring 40 and insufficient channels that affect drainage efficiency. Furthermore, this step still uses the pressure relief channel as the pressure relief structure, eliminating the need to cut in the protective ring 40. This maintains the ease of assembly of the actuator and its adaptability to actuators that rotate and reciprocate simultaneously. Moreover, by precisely controlling the number of channels to ensure timely oil discharge, the oil film pressure between the seal 30 and the cylinder 10, as well as the starting friction of the piston 20, can be further reduced, thus reducing system energy loss and extending the service life of the seal 30. This meets the high-performance requirements of aviation hydraulic systems for reliable sealing and low friction of the actuator.

[0088] Example 2:

[0089] In this embodiment, the present application provides a hydraulic actuation mechanism with a low-friction sealing structure, manufactured using the manufacturing method of the low-friction sealing structure hydraulic actuation mechanism in any of the embodiments. Figure 3As shown, the hydraulic actuation mechanism of the low-friction sealing structure includes a cylinder 10, a piston 20, and a protective ring 40.

[0090] The piston 20 is slidably disposed in the cylinder 10 along the axis of the cylinder 10, and the piston 20 rotates relative to the cylinder 10. By setting the piston 20, which slides along the axis of the cylinder 10 and can rotate relative to the cylinder 10, it is possible to adapt to the working conditions of the actuator that rotates and reciprocates at the same time, and meet specific usage requirements.

[0091] The seal 30 is coaxially fixed to the piston 20, and the seal 30 slides against the inner circumferential wall of the cylinder 10. The annular seal 30 is coaxially fixed to the piston 20 and slides against the inner circumferential wall of the cylinder 10, providing a basic sealing function for the hydraulic system and preventing oil leakage. The protective ring 40 is coaxially fixed to the piston 20 and slides against the inner circumferential wall of the cylinder 10, which can help the seal 30 maintain sealing stability. At the same time, it forms a first gap with the seal 30. A second gap is formed between the piston 20 and the inner circumferential wall of the cylinder 10 on the side of the protective ring 40 away from the seal 30. Both provide reasonable space for oil flow.

[0092] The protective ring 40 is coaxially fixed with the piston 20; the protective ring 40 slides against the inner peripheral wall of the cylinder 10; the protective ring 40 and the sealing element 30 are arranged at intervals along the axis of the cylinder 10; there is a first gap between the protective ring 40 and the sealing element 30; there is a second gap between the outer peripheral wall of the piston 20 and the inner peripheral wall of the cylinder 10; the second gap is located on the side of the protective ring 40 away from the sealing element 30; the outer peripheral wall of the protective ring 40 has a pressure relief channel; the pressure relief channel connects the first gap and the second gap. The pressure relief channel on the outer peripheral wall of the protective ring 40 connects the first gap and the second gap, allowing the oil trapped in the first gap to be smoothly discharged to the second gap, thus avoiding the pressure trapping phenomenon under bidirectional alternating pressure conditions. The entire structure does not require any cuts on the protective ring 40, which improves the assembly convenience of the piston 20 and the cylinder 10, reduces the oil film pressure between the seal 30 and the cylinder 10 and the starting friction of the piston 20, reduces system energy loss, slows down the wear of the seal 30 and the cylinder 10, and extends the service life of the sealing structure and the entire actuating mechanism, meeting the high-performance requirements of aviation hydraulic systems for sealing reliability and low friction of the actuator.

[0093] In other embodiments, two protective rings 40 are provided; the seal 30 is located between the two protective rings 40. The pressure relief passage extends axially along the piston 20; the hydraulic passage is parallel to or at an angle to the axis of the piston 20.

[0094] For aviation hydraulic actuators, full performance should be guaranteed within a temperature range of -40 to 135°C. Given that the dynamic viscosity η of aviation hydraulic oil at -40°C is approximately 0.52 Pa•s, assuming a seal size d = 50 mm, a maximum speed of v = 6 m / s during piston 20's movement, and a maximum pressure gradient WA = 2656 MPa / mm at the inflection point, then substituting into the formula:

[0095] ;

[0096] If we consider a maximum clearance of h0 = 0.2 mm for the seal 30, and a semi-circular microchannel with a diameter of d0 = 0.2 mm is provided on the outer diameter of the protective ring 40, then the area of ​​a single microchannel is S1 = π × 0.12 / 2 = 0.017 mm². 2 Therefore, the required number of microchannels N is ≥ 0.08 / 0.017 = 4.7, so we choose 5 microchannels N.

[0097] Those skilled in the art will understand that the above embodiments are specific examples of implementing this disclosure, and in practical applications, various changes can be made in form and detail without departing from the scope of this disclosure.

Claims

1. A method for manufacturing a low-friction sealing structure hydraulic actuation mechanism, characterized in that, The manufacturing method of the low-friction sealing structure hydraulic actuation mechanism includes: A first functional relationship is determined between the oil film pressure between the seal and the cylinder of the semi-finished actuation mechanism and the axial position of the cylinder; wherein, the semi-finished actuation mechanism includes the cylinder, a piston, the seal, and a protective ring; the piston is slidably disposed in the cylinder; the seal and the protective ring are respectively coaxially fixed with the piston; the seal and the protective ring are slidably fitted against the inner circumferential wall of the cylinder; Obtain the growth rate of the oil film pressure in the first functional relationship; wherein the growth rate is greater than 0; According to the formula Determine the first oil film thickness at the axial position of the cylinder corresponding to the growth rate; where w A The growth rate; h A η is the thickness of the first oil film; η is the dynamic viscosity of the oil film; v is the moving speed of the piston; According to the formula Determine the thickness of the second oil film at the location of maximum oil film pressure; wherein, The thickness of the second oil film; According to the formula The thickness of the third oil film on the outer side of the sealing interface between the seal and the cylinder is determined; where h0 is the thickness of the third oil film; k is a proportional value; k < 1; The oil volume in the first gap between the seal and the protective ring is determined based on the thickness of the third oil film. The size parameters of the pressure relief channel are determined based on the oil volume. The pressure relief channel is machined on the outer circumferential wall of the protective ring according to the dimensional parameters; wherein, the pressure relief channel is used to connect the first gap and the second gap; the second gap is located between the outer circumferential wall of the piston and the inner circumferential wall of the cylinder; the second gap is located on the side of the protective ring away from the seal.

2. The manufacturing method of a low-friction sealing structure hydraulic actuation mechanism according to claim 1, characterized in that, The first functional relationship between the oil film pressure between the seal and the cylinder of the semi-finished actuation mechanism and the axial position of the cylinder includes: A macroscopic finite element analysis was performed on the semi-finished actuation mechanism to form a second functional relationship between the contact stress between the seal and the cylinder and the axial position of the cylinder. According to the formula A first functional relationship is determined between the oil film pressure between the seal and the cylinder and the axial position of the cylinder; wherein, The oil film pressure; denoted as the contact stress; x represents the axial position of the cylinder.

3. The manufacturing method of a low-friction sealing structure hydraulic actuation mechanism according to claim 1, characterized in that, According to the formula Before the step of determining the first oil film thickness at the axial position of the cylinder corresponding to the growth rate, the manufacturing method of the low-friction sealing structure hydraulic actuation mechanism further includes: The Reynolds equation for determining the oil film between the seal and the cylinder. Where h(x) is the oil film thickness; Differentiating the Reynolds equation yields the following second-order differential equation: Where, u0 = dv / dx; based on The thickness of the first oil film is determined according to the second-order differential equation. .

4. The manufacturing method of a low-friction sealing structure hydraulic actuation mechanism according to claim 3, characterized in that, According to the formula Before the step of determining the second oil film thickness at the location of maximum oil film pressure, the manufacturing method of the low-friction sealing structure hydraulic actuation mechanism further includes: Based on w A =(dp / dx) A The Reynolds equation and dp / dx=0 determine the thickness of the second oil film as follows: .

5. The manufacturing method of a low-friction sealing structure hydraulic actuation mechanism according to claim 1, characterized in that, According to the formula Before the step of determining the thickness of the third oil film on the outer side of the sealing interface between the seal and the cylinder, the manufacturing method of the low-friction sealing structure hydraulic actuation mechanism further includes: Obtain the velocity distribution of the oil film at the location with the highest oil film pressure; Based on the fact that the flow velocity distribution is linearly varied along the radial direction of the cylinder, k is determined to be 0.4~0.

6.

6. The manufacturing method of a low-friction sealing structure hydraulic actuation mechanism according to claim 5, characterized in that, The manufacturing method of the low-friction sealing structure hydraulic actuation mechanism further includes: Based on the flow velocity distribution, where the flow velocity changes linearly from the outer radial direction to the inner diameter of the cylinder to 0, k=0.5 is determined.

7. The manufacturing method of a low-friction sealing structure hydraulic actuation mechanism according to claim 1, characterized in that, The step of determining the oil volume of the first gap between the seal and the protective ring based on the thickness of the third oil film includes: According to the formula The volume of oil per unit length of the first gap between the seal and the protective ring is determined; the unit length is the length along the axial direction of the cylinder; where d is the outer diameter of the seal.

8. A method for manufacturing a low-friction sealing structure hydraulic actuation mechanism according to claim 7, characterized in that, The dimensional parameters include the cross-sectional area; Determining the size parameters of the pressure relief channel based on the oil volume includes: Obtain the maximum extrusion gap of the seal; The cross-sectional area of ​​the pressure relief channel is determined according to the formula S1≤π(d0 / 2)2; where S1 is the cross-sectional area and d0 is the maximum extrusion gap.

9. A method for manufacturing a low-friction sealing structure hydraulic actuation mechanism according to claim 8, characterized in that, The size parameters also include quantity; The step of determining the size parameters of the pressure relief channel based on the oil volume also includes: The number of pressure relief channels is determined according to the formula N≥S0 / S1; where N is the number.

10. A hydraulic actuation mechanism with a low-friction sealing structure, manufactured using the manufacturing method of any one of claims 1-9; characterized in that, The hydraulic actuation mechanism of the low-friction sealing structure includes: cylindrical body; A piston, which is slidably disposed in the cylinder along the axis of the cylinder; the piston rotates relative to the cylinder; A sealing element, the sealing element being annular; the sealing element being coaxially fixed with the piston; the sealing element being slidably fitted against the inner peripheral wall of the cylinder; A protective ring is fixed coaxially with the piston; the protective ring slides against the inner circumferential wall of the cylinder; the protective ring and the sealing element are arranged at intervals along the axis of the cylinder; a first gap exists between the protective ring and the sealing element; a second gap exists between the outer circumferential wall of the piston and the inner circumferential wall of the cylinder; the second gap is located on the side of the protective ring away from the sealing element; the outer circumferential wall of the protective ring has a pressure relief channel; the pressure relief channel connects the first gap and the second gap.

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