A flexible anti-stiction valve sleeve and method of controlling the same

Abstract

The present application belongs to the technical field of electro-hydraulic servo valve, and particularly relates to a flexible anti-stuck valve sleeve and a control method thereof. The valve sleeve comprises: a valve sleeve main body, a non-oil distribution window section of which is processed with longitudinal micro-slits, so that the valve sleeve has radial elastic expansion capability; at least one shape memory alloy split ring, which is sleeved on the outer circumference of the valve sleeve main body at an axial position corresponding to the micro-slits, generates radial expansion force when heated to above the reverse phase change temperature, forces the valve sleeve main body to expand radially to increase the mating clearance with the valve core, and releases the stuck valve core; and a flexible sealing layer formed on the outer circumference to prevent hydraulic oil from leaking through the micro-slits and capable of deforming synchronously with the valve sleeve. The control method comprises: when stuck is monitored, the SMA split ring is powered and heated to expand the valve sleeve to release the stuck; and after the stuck is released, the current is cut off to cool and reset by circulating hydraulic oil. The present application actively expands the mating clearance in the radial dimension to forcibly release the stuck, and has the advantages of large driving force and no interference with axial control accuracy.

Description

Technical Field

[0001] This invention relates to the field of electro-hydraulic servo valve technology, specifically to a flexible anti-jamming valve sleeve and its control method. Background Technology

[0002] Electro-hydraulic servo valves are the core control components of electro-hydraulic servo systems. They achieve precise control of hydraulic oil flow direction and flow rate through the precise axial sliding of the valve core within the valve sleeve. To ensure control accuracy and volumetric efficiency, the clearance between the valve core and the valve sleeve is typically only 2 to 5 micrometers. However, while this extremely small clearance brings high efficiency, it also makes the servo valve highly susceptible to "jamming" failures due to the embedding of hydraulic oil contaminant particles, hydraulic clamping force, or uneven thermal expansion. This means the valve core becomes stuck within the valve sleeve and cannot move, leading to control failure in minor cases and safety accidents in severe cases.

[0003] To address the servo valve jamming problem, existing technologies mainly employ two solutions: one is to superimpose a high-frequency chatter signal onto the control signal, using an electromagnetic torque motor to drive the valve core to generate micro-amplitude high-frequency vibrations, replacing static friction with dynamic friction to reduce particle deposition; the other is to machine a pressure equalization groove on the outer circumference of the valve core to balance radial hydraulic pressure. However, the former has limited electromagnetic driving force and cannot provide sufficient thrust when facing severe contamination or thermal expansion causing seizure; the latter is a passive static improvement and cannot cope with dynamic jamming under varying operating conditions, and the pressure equalization groove increases internal leakage, sacrificing volumetric efficiency.

[0004] In recent years, shape memory alloys (MMEs) have begun to be applied in the valve field due to their high energy density and unique phase change actuation characteristics. Some existing technologies explore solutions using MME springs to drive the axial reciprocating motion of valve cores, but these are essentially conventional applications of MMEs in axial valve core actuation and do not involve improvements to the valve sleeve structure. Other existing technologies attempt to arrange MME elements radially to change the compression force of the seal, but these are applied to shaft seals, where the technical purpose is to maintain the sealing effect rather than to eliminate mechanical jamming. This belongs to a different technical field than servo valve anti-jamming and addresses opposite technical problems.

[0005] Therefore, there is an urgent need to develop an anti-jamming valve sleeve that can actively expand the gap between the valve core and the valve sleeve in the radial dimension without disassembling the valve body, so as to achieve forced release. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings and deficiencies of the existing technology and to provide a flexible anti-jamming valve sleeve and its control method, so as to realize the active expansion of the valve sleeve from the radial dimension to release the jammed valve core by utilizing the high energy density phase change driving force of shape memory alloy without disassembling the valve body.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a flexible anti-jamming valve sleeve, comprising: The valve sleeve body is made of a highly elastic metal material. Its inner hole is used to form a precise sliding fit clearance with the valve core of the servo valve. The valve sleeve body has at least two symmetrically distributed longitudinal micro slits machined in the axial section of its non-oil distribution window. Each of the longitudinal micro slits extends axially and radially penetrates the valve sleeve wall thickness, so that the valve sleeve body has radial elastic expansion capability in the section where the longitudinal micro slits are provided. At least one shape memory alloy segment ring, made of nickel-titanium alloy and possessing a two-way shape memory effect, is fitted onto the outer circumference of the valve sleeve body in a close-fitting manner, with its axial position corresponding to the axial segment where the longitudinal micro-slit is located. The shape memory alloy segment ring is in a soft state in the low-temperature martensitic phase, and its inner diameter matches the outer diameter of the valve sleeve body, without applying additional radial load to the valve sleeve body. When heated above the inverse phase transformation temperature, the shape memory alloy segment ring transforms from martensite to austenite and recovers its memory expansion shape, thereby generating a radially outward expansion force. This forces the valve sleeve body to undergo radial elastic expansion at the longitudinal micro-slit, increasing the fit clearance between the inner bore of the valve sleeve body and the valve core. A flexible sealing layer, formed of oil-resistant elastic material on the outer periphery of the valve sleeve body and the shape memory alloy dividing ring, prevents hydraulic oil from leaking outward through the longitudinal micro-slits. The radial elastic stiffness of the flexible sealing layer is less than the metallic elastic stiffness of the valve sleeve body, allowing it to deform synchronously with the radial expansion and contraction of the valve sleeve body. The longitudinal micro-slits on the valve sleeve body impart radial elastic expansion capability to the valve sleeve. Combined with the radial expansion force generated by the shape memory alloy dividing ring during thermal phase change, and the radially compliant sealing of the flexible sealing layer, this achieves the function of actively expanding the gap between the valve core and the valve sleeve in the radial dimension to release jamming without disassembling the valve body. It possesses the triple characteristics of rigid guidance, flexible expansion, and reliable sealing.

[0008] In some embodiments, the expansion shape remembered by the high-temperature austenitic phase of the shape memory alloy segmented ring is an arc segment or a complete ring with a first radius of curvature, and is constrained to a shape with a second radius of curvature in the low-temperature martensitic phase, wherein the first radius of curvature is greater than the second radius of curvature, so that the restoring force generated by the shape memory alloy segmented ring during the thermal reverse phase transformation is directed in the radially outward direction. The high-temperature memory shape radius of curvature of the shape memory alloy segmented ring is greater than the low-temperature constrained shape radius of curvature, ensuring that the restoring force generated during the reverse phase transformation is directed in the radially outward direction, providing a directional driving force for the expansion of the valve sleeve.

[0009] In some embodiments, when the shape memory alloy dividing ring is not driven, the valve sleeve body maintains an initial fit clearance by its own elastic preload. This elastic preload is greater than the radial force generated by the servo valve's rated working pressure acting on the inner wall of the valve sleeve body. The elastic preload of the valve sleeve body is greater than the radial force generated by the rated working pressure, ensuring a stable fit clearance under normal operating conditions. Expansion only occurs when the shape memory alloy is driven, avoiding accidental triggering due to hydraulic fluctuations.

[0010] In some embodiments, the longitudinal microslit is fabricated using laser processing or electrical discharge machining, and its width and length are configured such that the valve sleeve body can generate a uniform radial expansion of 1 to 3 micrometers under the drive of the shape memory alloy dividing ring. The expansion range of the longitudinal microslit is 1 to 3 micrometers, enabling the valve sleeve to generate a uniform radial expansion of 1 to 3 micrometers under the drive of the shape memory alloy, which can both release the stuck valve core and prevent excessive expansion from affecting the reset accuracy.

[0011] In some embodiments, the flexible sealing layer is a high-temperature resistant fluororubber layer, which is tightly bonded to the outer surface of the valve sleeve body and the shape memory alloy dividing ring by heat shrinking or bonding, forming a self-tightening seal under the pressure of the working hydraulic oil. The flexible sealing layer is made of high-temperature resistant fluororubber material and is formed by heat shrinking or bonding, and has self-tightening sealing characteristics. While ensuring sealing reliability, its elastic stiffness is much lower than that of the valve sleeve body, so as not to hinder the radial expansion and retraction of the valve sleeve.

[0012] In some embodiments, the highly elastic metallic material is beryllium bronze or precipitation-hardened stainless steel. The valve sleeve body is made of beryllium bronze or precipitation-hardened stainless steel, which combines high elastic limit and excellent wear resistance, ensuring accurate springback and reset after repeated expansion.

[0013] In some embodiments, the number of longitudinal microslits is 10, which are evenly and symmetrically distributed along the circumference of the valve sleeve body. The 10 evenly and symmetrically distributed microslits ensure uniform and symmetrical deformation of the valve sleeve during expansion, avoiding uneven force on the valve core caused by eccentric expansion.

[0014] The present invention also provides a control method for a flexible anti-jamming valve sleeve, comprising the following steps: Step S1: Detect the actual axial displacement of the valve core and compare it with the expected displacement corresponding to the valve core control signal. When the deviation exceeds the preset threshold and continues for a preset time, it is determined that jamming has occurred. Step S2: After the jamming determination, an instantaneous current is passed through the shape memory alloy dividing ring to perform Joule heating, so that its temperature rises rapidly to above the reverse phase transformation temperature, triggering the reverse phase transformation from martensite to austenite. The shape memory alloy dividing ring generates a radially outward expansion force, forcing the valve sleeve body to undergo radial elastic expansion at the longitudinal micro-slit, thereby increasing the fitting clearance between the valve core and the inner hole of the valve sleeve body, and releasing the jammed valve core. Step S3: After unblocking, the instantaneous current is cut off. The hydraulic oil circulating within the servo valve system is used as a cooling medium to forcibly cool the shape memory alloy segment ring, lowering its temperature below the martensitic phase transformation temperature. The shape memory alloy segment ring returns to its soft state, and the valve sleeve body retracts to its initial precision fit clearance due to its own elastic restoring force. The servo valve returns to normal operation. This complete closed-loop control process, consisting of monitoring, heating to unblock, and cooling to reset, achieves automatic identification of jams and on-demand triggering of unblocking. After unblocking, the precision fit is automatically restored, demonstrating a high degree of intelligence.

[0015] In some embodiments, in step S1, the actual axial displacement of the valve core is detected by a displacement sensor; the preset threshold is set according to the rated control accuracy of the servo valve, and the preset time is set to 50 milliseconds to 200 milliseconds according to the system response characteristics. Using a displacement sensor to detect and set reasonable deviation thresholds and durations ensures the accuracy and timeliness of jamming detection, avoiding false triggering or missed detection.

[0016] In some embodiments, in step S2, the instantaneous current applied is a pulsed current, and the energizing duration is 0.5 to 2 seconds, raising the temperature of the shape memory alloy segmented ring above its austenitic reverse phase transformation end temperature; in step S3, the shape memory alloy segmented ring is cooled by the hydraulic oil circulating in the servo valve, lowering its temperature below the martensitic phase transformation end temperature. Using a pulsed current to rapidly heat to above the phase transformation temperature within 0.5 to 2 seconds results in a rapid unlocking response; natural cooling and reset using circulating hydraulic oil eliminates the need for an additional cooling device.

[0017] The beneficial effects of this invention are: First, a shape memory alloy segmented ring is fitted around the outer circumference of the valve sleeve. Utilizing the radial expansion force generated when the ring is heated above the inverse phase transformation temperature, the valve sleeve is forced to undergo radial elastic expansion at the longitudinal micro-slit, thereby increasing the fit clearance between the valve core and the valve sleeve, allowing the stuck valve core to be released. The shape memory alloy can generate recovery stress in the hundreds of megapascals during the inverse phase transformation process, providing sufficient driving force to overcome the static frictional resistance under severe jamming, thus achieving forced release.

[0018] Secondly, the combined design of "longitudinal micro-slits and flexible sealing layers" enables the valve sleeve to perform dual functions: during normal operation, the valve sleeve acts as a rigid integral component, providing stable and precise guidance and sealing; in the event of jamming, the section containing the longitudinal micro-slits can undergo controllable radial elastic expansion driven by the shape memory alloy dividing ring. After releasing the valve core, it retracts and resets itself using its own elastic restoring force, restoring the initial fit clearance. This rigid-flexible coupling structure achieves precise and controllable radial deformation while ensuring the overall continuity and sealing performance of the valve sleeve.

[0019] Third, the release action only acts on the radial dimension of the valve sleeve, causing a slight radial expansion of the valve sleeve to release the valve core constraint. It does not change the force balance relationship of the valve core in the axial direction, so it will not introduce zero position offset and ensure the original control accuracy of the servo valve.

[0020] Fourth, the shape memory alloy segment ring is energized only when jamming is detected and de-energized after unblocking. It uses the circulating hydraulic oil in the servo valve system as a cooling medium to cool and reset naturally, without the need for an additional cooling device. It has low power consumption and the flexible contact reduces hard wear between the valve core and valve sleeve, which helps to extend the service life of precision mating pairs. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0022] Figure 1 This is an exploded view of an embodiment of the present invention; Figure 2 This is a radial cross-sectional view of an embodiment of the present invention; Figure 3 This is a schematic diagram comparing the morphology of the shape memory alloy segmented ring in the low-temperature martensite phase and the high-temperature austenite phase according to an embodiment of the present invention, wherein (a) is the low-temperature martensite phase state and (b) is the high-temperature austenite phase state. Figure 4 This is a schematic diagram illustrating the installation and deployment of the anti-jamming valve sleeve in a servo valve according to an embodiment of the present invention; Figure 5 This is a flowchart of the flexible anti-jamming valve sleeve control method according to an embodiment of the present invention. Detailed Implementation

[0023] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings, are intended to cover non-exclusive inclusion.

[0025] The directional and positional terms used in this invention, such as up, down, front, back, left, right, inside, outside, top, bottom, side, etc., are merely for reference to the accompanying drawings. Therefore, the directional and positional terms used are for illustrating and understanding this invention, and not for limiting the scope of protection of this invention.

[0026] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments: like Figure 1 , 2 As shown, this embodiment provides a flexible anti-jamming valve sleeve, which is assembled inside the valve body 5 of the electro-hydraulic servo valve and forms a precision sliding fit with the valve core 4.

[0027] The valve sleeve body 1 is made of a metal material with both high elastic limit and excellent wear resistance, such as beryllium bronze or precipitation-hardened stainless steel. It is cylindrical in shape, with a precision fit clearance of 2 to 5 micrometers between its inner bore 11 and the outer surface of the valve core 4. On the cylindrical wall of the valve sleeve body 1, in the axial middle section avoiding the oil distribution window, 10 longitudinal micro-slits 12 are cut by precision laser machining, evenly and symmetrically distributed along the circumference and extending a predetermined length axially. These 10 longitudinal micro-slits 12 radially penetrate the valve sleeve wall thickness, and their width is preferably 20 to 50 micrometers. The presence of the longitudinal micro-slits 12 makes the valve sleeve body 1 a flexible section that can elastically expand radially in this axial section, while the slit-free sections at its front and rear ends maintain complete rigidity, ensuring the overall guiding accuracy of the valve sleeve and the installation positioning accuracy with the valve body.

[0028] The shape memory alloy segment ring 2 is made of a near-equal atomic ratio nickel-titanium alloy with a two-way shape memory effect. It is tightly fitted onto the outer circumference of the valve sleeve body 1 with an interference or transition fit, and its axial position precisely covers the flexible segment where the longitudinal micro-slit 12 is located. For example... Figure 3 As shown, the shape memory alloy segmented ring 2 in the low-temperature martensitic phase (such as...) Figure 3(a) The material is soft, and its inner diameter is constrained by the outer diameter of the valve sleeve body 1 in a state of second radius of curvature; when the temperature rises above the end temperature of the austenite reverse phase transformation (such as... Figure 3 In section (b), a reverse phase transformation from martensite to austenite occurs, spontaneously recovering to the first radius of curvature state memorized during high-temperature training. This first radius of curvature is greater than the second radius of curvature, thereby generating a restoring force pointing radially outward. This restoring stress can reach the level of 200 to 500 MPa, which is sufficient to overcome the elastic resistance of the valve sleeve body 1 and cause it to expand outward at the longitudinal micro-slit 12. When the shape memory alloy dividing ring 2 is not driven, the valve sleeve body 1 maintains the initial fit clearance by its own elastic preload. This elastic preload is greater than the radial force generated by the rated working pressure of the servo valve acting on the inner wall of the valve sleeve body 1, ensuring that the valve sleeve body 1 only expands radially when driven by the shape memory alloy dividing ring 2.

[0029] The flexible sealing layer 3 is made of high-temperature resistant fluororubber and is tightly wrapped around the outer circumference of the valve sleeve body 1 and the shape memory alloy segmented ring 2 through a heat-shrink process. The wall thickness of the flexible sealing layer 3 is 0.3 to 0.8 mm, and its Shore hardness is preferably 60A to 75A to ensure that its elastic stiffness is much lower than that of the metal elastic stiffness of the valve sleeve body 1, and will not create significant resistance to the radial expansion of the valve sleeve. In the working state, the high-pressure oil of the hydraulic system acts on the inner surface of the flexible sealing layer 3, further pressing it against the outer wall of the valve sleeve body 1 to form a reliable self-tightening seal, effectively preventing hydraulic oil from leaking to the outside through the longitudinal micro-slit 12.

[0030] like Figure 4 As shown, in the assembled state, the valve sleeve body 1 is installed in the inner hole of the valve body 5 of the servo valve through the outer circular positioning surfaces of its front and rear ends, and the valve core 4 can slide axially through the inner hole 11 of the valve sleeve body 1. The mating surface between the valve core 4 and the inner hole 11 of the valve sleeve body 1 constitutes the core anti-jamming area, especially at the throttling edge of the valve port.

[0031] The following combination Figure 5 The control method of this embodiment is explained.

[0032] After the system is powered on, the real-time monitoring module continuously acquires the actual axial displacement signal of the valve core 4 and compares it with the expected displacement corresponding to the control signal output by the servo amplifier. The real-time monitoring module can use an LVDT displacement sensor or a current deviation monitoring circuit based on valve core displacement feedback. Once the deviation between the actual displacement and the expected displacement exceeds a preset threshold and the duration exceeds a preset time, the control system determines that a jam has occurred. The preset threshold is set according to the rated control accuracy of the servo valve, for example, 5% of the full scale; the preset time is set according to the system response characteristics from 50 milliseconds to 200 milliseconds, for example, 100 milliseconds.

[0033] Upon detection of jamming, the control system applies a momentary pulse current to the shape memory alloy segment ring 2, utilizing the Joule heating effect to heat the SMA material to above its austenitic reverse transformation end temperature (Af) within 0.5 to 2 seconds. The shape memory alloy segment ring 2 undergoes a reverse transformation, generating a strong radial outward expansion restoring force. This forces the valve sleeve body 1 to undergo elastic expansion of 1 to 3 micrometers at the longitudinal micro-slit 12, thereby instantaneously increasing the clearance between the valve core 4 and the inner hole 11. Contaminant particles in the jammed clearance are then flushed away by the flowing hydraulic oil, and the physical interference caused by thermal expansion is eliminated, allowing the valve core 4 to regain its free movement capability.

[0034] After the unlocking action is completed, the control system cuts off the drive current to the shape memory alloy segment ring 2. Due to the continuous circulation of hydraulic oil inside the servo valve body, this flowing hydraulic oil acts as a natural cooling medium, rapidly carrying away the heat from the shape memory alloy segment ring 2, cooling it below the martensitic transformation end temperature (Mf). The shape memory alloy segment ring 2 re-enters the soft martensite state, and its elastic modulus drops sharply. At this time, the valve sleeve body 1, relying on the elastic potential energy stored in its highly elastic metallic material, automatically retracts to its initial shape, closing the expansion of the longitudinal micro-slit 12. The mating clearance returns to its initial 2 to 5 micrometers, and the servo valve re-enters the high-precision normal operating mode. The entire unlocking-reset cycle can be completed within seconds.

[0035] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this invention; the scope of protection of this invention is defined by the claims in the claims, and all equivalent changes and modifications made in accordance with this invention are within the scope of protection of this patent.

Claims

1. A flexible anti-jamming valve sleeve, characterized in that: include: The valve sleeve body is made of a highly elastic metal material. Its inner hole is used to form a precise sliding fit clearance with the valve core of the servo valve. The valve sleeve body has at least two symmetrically distributed longitudinal micro slits machined in the axial section of its non-oil distribution window. Each of the longitudinal micro slits extends axially and radially penetrates the valve sleeve wall thickness, so that the valve sleeve body has radial elastic expansion capability in the section where the longitudinal micro slits are provided. At least one shape memory alloy segment ring, made of nickel-titanium alloy and possessing a two-way shape memory effect, is fitted onto the outer circumference of the valve sleeve body in a close-fitting manner, with its axial position corresponding to the axial segment where the longitudinal micro-slit is located. The shape memory alloy segment ring is in a soft state in the low-temperature martensitic phase, and its inner diameter matches the outer diameter of the valve sleeve body, without applying additional radial load to the valve sleeve body. When heated above the inverse phase transformation temperature, the shape memory alloy segment ring transforms from martensite to austenite and recovers its memory expansion shape, thereby generating a radially outward expansion force. This forces the valve sleeve body to undergo radial elastic expansion at the longitudinal micro-slit, increasing the fit clearance between the inner bore of the valve sleeve body and the valve core. A flexible sealing layer, made of oil-resistant elastic material, is formed on the outer periphery of the valve sleeve body and the shape memory alloy dividing ring. It is used to prevent hydraulic oil from leaking outward through the longitudinal micro-slit. The radial elastic stiffness of the flexible sealing layer is less than the metallic elastic stiffness of the valve sleeve body, so that it can deform synchronously with the radial expansion and contraction of the valve sleeve body.

2. The flexible anti-jamming valve sleeve according to claim 1, characterized in that: The shape memory alloy segmented ring is memoryed by the high-temperature austenitic phase as an arc segment or a complete ring with a first radius of curvature. In the low-temperature martensitic phase, it is constrained to a shape with a second radius of curvature, wherein the first radius of curvature is greater than the second radius of curvature, so that the restoring force generated by the shape memory alloy segmented ring during the thermal reverse phase transformation points in the radial outward direction.

3. The flexible anti-jamming valve sleeve according to claim 1, characterized in that: When the shape memory alloy dividing ring is not driven, the valve sleeve body maintains the initial fit clearance by its own elastic preload, which is greater than the radial force generated by the rated working pressure of the servo valve acting on the inner wall of the valve sleeve body.

4. The flexible anti-jamming valve sleeve according to claim 1, characterized in that: The longitudinal microslits are made by laser processing or electrical discharge machining, and their width and length are configured to enable the valve sleeve body to generate a uniform radial expansion of 1 to 3 micrometers under the drive of the shape memory alloy dividing ring.

5. The flexible anti-jamming valve sleeve according to claim 1, characterized in that: The flexible sealing layer is a high-temperature resistant fluororubber layer, which is tightly bonded to the outer surface of the valve sleeve body and the shape memory alloy dividing ring by heat shrinking or bonding, forming a self-tightening seal under the pressure of working hydraulic oil.

6. The flexible anti-jamming valve sleeve according to claim 1, characterized in that: The highly elastic metallic material is beryllium bronze or precipitation-hardening stainless steel.

7. The flexible anti-jamming valve sleeve according to any one of claims 1-6, characterized in that: The number of longitudinal micro-slits is 10, which are evenly and symmetrically distributed along the circumference of the valve sleeve body.

8. A control method applied to the flexible anti-jamming valve sleeve according to any one of claims 1 to 7, characterized in that: Includes the following steps: Step S1: Detect the actual axial displacement of the valve core and compare it with the expected displacement corresponding to the valve core control signal. When the deviation exceeds the preset threshold and continues for a preset time, it is determined that jamming has occurred. Step S2: After the jamming determination, an instantaneous current is passed through the shape memory alloy dividing ring to perform Joule heating, so that its temperature rises rapidly to above the reverse phase transformation temperature, triggering the reverse phase transformation from martensite to austenite. The shape memory alloy dividing ring generates a radially outward expansion force, forcing the valve sleeve body to undergo radial elastic expansion at the longitudinal micro-slit, thereby increasing the fitting clearance between the valve core and the inner hole of the valve sleeve body, and releasing the jammed valve core. Step S3: After unlocking, cut off the instantaneous current, and use the hydraulic oil circulating in the servo valve system as a cooling medium to force-cool the shape memory alloy segment ring, so that its temperature drops below the martensitic phase transformation temperature. The shape memory alloy segment ring returns to a soft state, and the valve sleeve body retracts to the initial precision fit gap by its own elastic restoring force, and the servo valve returns to normal working state.

9. The control method for the flexible anti-jamming valve sleeve according to claim 8, characterized in that: In step S1, the actual axial displacement of the valve core is detected by a displacement sensor; the preset threshold is set according to the rated control accuracy of the servo valve, and the preset time is set to 50 milliseconds to 200 milliseconds according to the system response characteristics.

10. The control method for the flexible anti-jamming valve sleeve according to claim 8, characterized in that: In step S2, the instantaneous current is a pulse current, and the energizing duration is 0.5 seconds to 2 seconds, so that the temperature of the shape memory alloy segment ring rises above its austenitic reverse phase transformation end temperature; in step S3, the hydraulic oil circulating in the servo valve is used to cool the shape memory alloy segment ring, so that its temperature drops below the martensitic phase transformation end temperature.

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