Lock release device based on separate nut and spacecraft

Abstract

The application provides a locking and releasing device based on a separation nut, comprising a shell, a separation unlocking assembly and a trigger assembly, the separation unlocking assembly comprises a separation nut for locking and pressing a rod, a roller and a nut support, the nut support is slidably connected with the shell along the Y-axis direction, the nut support has a separation nut mounting cavity, the separation nut is mounted in the separation nut mounting cavity, the separation nut is combined by at least two split nuts, the split nut is provided with a roller mounting groove, the roller is arranged on the roller mounting groove, and the roller is clamped between the nut support and the split nut. The application also provides a spacecraft. The application has the beneficial effects that: the explosive device is cancelled, the space occupation ratio is small, the impact is low, the safety is high, and the installation is convenient.

Description

Technical Field

[0001] The present invention relates to aerospace equipment, and in particular to a locking and releasing device based on a separation nut and a spacecraft. Background Art

[0002] In the traditional satellite field, the solar wing unlocking mechanism usually adopts a solar wing deployment mechanism in the form of pyrotechnics. The main principle is that when the solar wing is in a compressed state, it is locked to the solar wing base through a compression rod to achieve the locking function; when unlocking, the pyrotechnics first work to generate high-temperature and high-pressure gas to push the internal mechanism to cut off the pull rod to achieve the unlocking function; it has the characteristics of large impact, high cost, and large size, and during the installation process, a special strain gauge is required to measure the preload force, and the installation process is relatively complicated.

[0003] Due to the small size and light weight of microsatellites, traditional pyrotechnic solar panel locking and release devices will have a great impact on the satellite solar panels and the star body, occupy a large space, and are difficult to disassemble and assemble. Summary of the Invention

[0004] In order to solve the problems of pyrotechnic devices in the prior art, the present invention provides a locking and releasing device based on a separation nut and a spacecraft.

[0005] The present invention provides a locking and releasing device based on a separation nut, comprising a housing, a separation and unlocking assembly, and a trigger assembly, wherein the separation and unlocking assembly comprises a separation nut for locking a pressing rod, a roller, and a nut bracket, wherein the nut bracket is slidably matched with the housing along the Y-axis direction, the nut bracket has a separation nut mounting cavity, the separation nut is mounted within the separation nut mounting cavity, the separation nut is composed of at least two split nuts, the split nut is provided with a roller mounting groove, the roller is arranged on the roller mounting groove, the roller is clamped between the nut bracket and the split nut, the inner side surface of the nut bracket is provided with at least a partial roller unlocking groove capable of accommodating the roller, and the trigger assembly is connected to the nut bracket;

[0006] When locked, the roller is located outside the roller unlocking groove, and the split nut is kept intact under the support of the roller and locks the clamping rod, that is, the clamping rod is threadedly connected to the separation nut as a screw, and the nut bracket is located in the locked position under the restraint of the trigger assembly;

[0007] When unlocking, the trigger assembly releases the constraint on the nut bracket, and the nut bracket slides along the Y-axis to reach the unlocking position. The roller falls into the roller unlocking groove, and the split nut loses the support of the roller and disperses, no longer maintaining a complete state, but is in a split state, and loses the lock on the clamping rod, thereby completing the unlocking.

[0008] As a further improvement of the present invention, each split nut is correspondingly mounted with at least two rollers.

[0009] As a further improvement of the present invention, the trigger assembly includes a pre-tensioning rope, a pre-tensioning assembly for keeping the pre-tensioning rope in a tensioned state, and a cutter for cutting the pre-tensioning rope when unlocked. The separation and unlocking assembly also includes a driving spring for driving the nut bracket from a locked position to an unlocked position. One end of the pre-tensioning rope is connected to the nut bracket, and the other end is connected to the pre-tensioning assembly. Under the action of the pre-tensioning rope, the driving spring is clamped between the nut bracket and the shell.

[0010] As a further improvement of the present invention, the pre-tensioning assembly includes a base, an anti-loosening spring capable of keeping the pre-tensioning rope in a pre-tensioned state for a long time, a pressing sleeve, an adjustment screw and a sheath capable of adjusting the pre-tensioning force of the pre-tensioning rope. The base is fixed on the shell, and the pre-tensioning rope passes through the base, the anti-loosening spring, the pressing sleeve in turn and is connected to the adjustment screw. The sheath is fixedly connected to the base, the anti-loosening spring is clamped between the base and the pressing sleeve, the adjustment screw is threadedly connected to the sheath, and the adjustment screw is pressed against the pressing sleeve.

[0011] As a further improvement of the present invention, the pre-tightening rope is connected to the nut bracket via a set screw.

[0012] As a further improvement of the present invention, the shell is connected to a cover plate, and the separation nut, nut bracket, and drive spring are all located inside the shell.

[0013] As a further improvement of the present invention, the cutter adopts a resistance wire type double-layer hot knife.

[0014] As a further improvement of the present invention, a separation spring is clamped between the split nuts to drive them to separate.

[0015] As a further improvement of the present invention, when locked, under the support of the roller, a gap is provided between the split nut and the inner side surface of the nut bracket and they remain non-contact.

[0016] As a further improvement of the present invention, the separation nut adopts a two-lobed incomplete separation nut with a portion of the width cut off in the middle, and the width of the cut-off section is s.

[0017] As a further improvement of the present invention, the roller constrains the split nut in the X direction, and the split nut mounting cavity is square, with the Y-axis direction being its long side and the X-axis direction being its short side.

[0018] The proposed locking and release mechanism differs significantly from similar deployment mechanisms in that its split nut, a two-lobed, non-separable nut, offers both excellent opening synchronization and a minimal minimum expansion displacement, resulting in a smaller overall device size. The device's trigger assembly utilizes a cutter, eliminating the need for explosives, resulting in a low-impact, high-safety product.

[0019] As a further improvement of the present invention, the separation nut is made of 45# steel or TC4 titanium alloy.

[0020] As a further improvement of the present invention, the stress condition of the thread is analyzed based on the stress condition of the complete nut thread as follows:

[0021] The calculation formulas for the deformation δ1 caused by thread bending, the deformation δ2 caused by shear force on the thread, the deformation δ3 caused by the tilt of the thread root, the deformation δ4 caused by shear deformation of the thread root, and the deformation δ5 caused by radial force on the thread are as follows:

[0022] 1) Deformation caused by thread bending δ1

[0023] Decompose the normal pressure ω per unit width into the vertical component ωcosα and the horizontal component ωsinα, and the deformation is:

[0024]

[0025] Where ν is the Poisson's ratio of the bolt or nut;

[0026] a——thread root width;

[0027] b——the width of the thread pitch diameter;

[0028] c – the height from the mean diameter of the thread to the root of the thread;

[0029] E——elastic modulus;

[0030] 2) Deformation of thread caused by shear force δ2

[0031]

[0032] 4) Deformation δ3 caused by the inclination of the thread root

[0033]

[0034] 4) Deformation δ4 caused by shear deformation of the thread root

[0035]

[0036] Where p is the thread pitch;

[0037] 5) Deformation of thread caused by radial force δ5

[0038]

[0039]

[0040] Where δ 5b ——Deformation of bolt thread along radial contraction;

[0041] δ 5n ——Deformation of the nut thread along the radial expansion;

[0042] d p —effective diameter of the bolt thread;

[0043] D——Nominal diameter of nut thread;

[0044] ν b —Poisson’s ratio of the bolt material;

[0045] ν n ——Poisson’s ratio of the nut material.

[0046] In summary, the total deformation of the bolt and nut threads are

[0047]

[0048] Where k b ——Bolt thread elastic deformation parameter item;

[0049] k n ——Parameter item of elastic deformation of nut thread;

[0050] E b —Elastic modulus of bolt material;

[0051] E n ——Elastic modulus of nut material.

[0052] The vertical component of force ωcosα on the thread is the axial force dF(x) acting between x and x+dx.

[0053]

[0054] Where β is the thread lead angle;

[0055]

[0056] Where d2 is the thread diameter;

[0057] For the total load Fz of the bolt and nut thread engagement, considering that both the bolt and the nut are under tension, the initial contact point between the bolt and the nut is taken as the origin (the starting point of the first thread circle), and the force acting on the vertical surface of the bolt at x is F(x), then the bolt elongation Δb and the nut elongation Δn at x are respectively

[0058]

[0059]

[0060] Where A b ——bolt cross-sectional area;

[0061] A n ——cross-sectional area of ​​the nut;

[0062] According to the load-bearing conditions, the deformation coordination relationship is:

[0063] (Δ b -Δ n ) x＝x =(δ b +δ n ) x＝x -(δ b +δ n ) x＝0 (1-11)

[0064] Substitute equations (1-7), (1-9) and (1-10) into equation (1-11) and differentiate with respect to x to obtain

[0065]

[0066] in:

[0067]

[0068] The general solution obtained from formula (1-12) is:

[0069]

[0070] According to the boundary conditions:

[0071] [F(x)] x＝0 =0, [F(x)] x＝L =F z

[0072] It turns out that:

[0073]

[0074] Substituting the above formula into formula (1-8), we get

[0075]

[0076] By performing definite integration on equation (1-15), we can find the load Z borne by one circle of thread. i

[0077]

[0078] Where i is the i-th thread;

[0079] p—thread pitch.

[0080] As a further improvement of the present invention, based on the analysis of the stress conditions of the complete nut, the detailed design and analysis of the two-piece incomplete split nut are carried out as follows:

[0081] For a two-piece, incomplete split nut, the width s of the middle cutout section affects the minimum radial displacement of the split nut when the bolt is released, as well as the load conditions of each thread circle.

[0082] The nominal diameter of the two-piece incomplete split nut is D, the width of the cut-off section is s, and the thread distribution angle is Φ;

[0083] When the thread is loaded, the thread teeth are mainly subjected to shear stress and bending stress. Considering the strength of the bolt thread teeth, it is only necessary to verify the strength of the thread root. Therefore, for the load-bearing situation of the incomplete separation nut and bolt thread meshing, it is only necessary to check the shear stress and bending stress of the dangerous thread segment; for the load-bearing situation of the complete nut and bolt thread meshing, the last circle of thread has the largest load-bearing ratio. Corresponding to the load-bearing situation of the two-petal incomplete separation nut and bolt meshing, it can be inferred that the thread load-bearing ratio of the last two and a half circles is the largest, and the maximum load-bearing load of the last two and a half circles of thread is F. a for

[0084]

[0085] Where n is the last thread number;

[0086] The shear stress τ of the dangerous section of the thread is

[0087]

[0088] Where d1 is the bolt thread diameter;

[0089] B - the thickness of the bolt thread root, for triangular thread B = 0.75p;

[0090] φ=arccos(s / D)—thread distribution angle unit is rad;

[0091] Bending stress σ of the dangerous section of the thread b for

[0092]

[0093] Where h is the working height of the thread;

[0094]

[0095] Where d is the nominal diameter of the bolt.

[0096] The present invention also provides a spacecraft, comprising the locking and releasing device based on the separation nut.

[0097] The beneficial effects of the present invention are as follows: through the above scheme, the separation nut is in a tightening state when locked, and the tightening rod is locked to the separation nut to maintain the tightening state; when separated, the cutter serves as a trigger mechanism to trigger unlocking, drive the separation nut to separate, and the tightening rod is separated from the separation nut to achieve unlocking. It has the advantages of low impact, small structural volume, and easy disassembly and assembly, and is suitable for use in micro satellites. BRIEF DESCRIPTION OF THE DRAWINGS

[0098] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other solutions can be obtained based on these drawings without paying any creative work.

[0099] Figure 1 An exploded view of the lock release device based on the separation nut of the present invention is shown.

[0100] Figure 2 A side view of a locking state of a locking and releasing device based on a separation nut according to the present invention is shown.

[0101] Figure 3 A front view of the locking state of the locking and releasing device based on the separation nut of the present invention is shown.

[0102] Figure 4 Schematic diagrams of various types of thread deformation are shown.

[0103] Figure 5 A schematic diagram of thread load deformation is shown.

[0104] Figure 6 A schematic diagram showing the load distribution of each thread circle of M4×0.7 thread is shown.

[0105] Figure 7 A schematic diagram of a two-piece, incomplete split nut is shown.

[0106] Figure 8 The stress curve of the dangerous section of the thread tooth is shown in the graph of the width of the cut-off section of the two-petal nut.

[0107] In the figure: housing 1, split nut 2, roller 3, nut bracket 4, drive spring 5, separation spring 6, cover 7, set screw 8, cutter 9, pre-tightening rope 10, base 11, anti-loosening spring 12, pressure sleeve 13, adjustment screw 14, sheath 15. DETAILED DESCRIPTION

[0108] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0109] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present invention. In addition, the terms "first", "second" and the like are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second" and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0110] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0111] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0112] like Figures 1 to 8 As shown, the present invention provides a solar wing locking and releasing device with a separation nut, which eliminates pyrotechnics and has the characteristics of small space occupation, low impact, high safety, and easy installation.

[0113] The device mainly consists of three parts: a housing structure, a trigger assembly 200, and a separation and unlocking assembly 100.

[0114] The housing structure mainly consists of a housing 1 and a cover plate 7 .

[0115] The trigger assembly 200 mainly consists of a cutter 9, a pre-tightening rope 10, a base 11, an anti-loosening spring 12, a pressing sleeve 13, an adjusting screw 14, a sheath 15 and the like.

[0116] The separation and unlocking assembly 100 is mainly composed of a separation nut, a roller 3, a nut bracket 4, a driving spring 5, a separation spring 6, etc.

[0117] The separation nut is mainly composed of a plurality of split nuts 2, and the separation spring 6 is clamped between the plurality of split nuts 2 to drive the split nuts 2 to separate.

[0118] The separation and unlocking assembly 100 is located inside the housing 1 .

[0119] The trigger assembly 200 is connected to the side of the housing 1 .

[0120] The structural dimensions of the device may preferably be 120 mm×60 mm×20 mm.

[0121] The trigger assembly 200 is mainly used for locking and releasing. When locking, it keeps the separation nut locked on the locking object, such as the clamping rod. When unlocking, it triggers the locking release device to unlock; the separation unlocking assembly 100 is used to trigger the unlocking of the assembly 200. The internal driving spring drives the separation nut to separate to realize the unlocking function.

[0122] When the locking and releasing device provided by the present invention is in the locked state, one end of the pretensioning rope 10 in the trigger assembly 200 is connected to the release and unlocking assembly 100, and the other end is connected to the adjustment screw 14. The pretensioning rope 10 is kept in a pretensioned state by the anti-loosening spring 12 and the adjustment screw 14. During the pretensioning process, one end of the pretensioning rope 10 overcomes the force of the drive spring 5 in the release and unlocking assembly, while the other end passes through the base 11, the pressure sleeve 13, and the adjustment screw 14 for fixation. The pretensioning force of the pretensioning rope 10 can be adjusted by the adjustment screw 14. At the same time, the anti-loosening spring 12 provides anti-loosening compensation for the creep of the pretensioning rope 10, ensuring that the pretensioning rope 10 remains in a long-term pretensioned state.

[0123] The cutter 9 adopts a resistance wire double-layer hot knife. Under the condition of power supply current 2A±0.2A and vacuum condition, the working time of the cutter 9 is about ten seconds, which can normally cut the pre-tightened rope to achieve the triggering effect.

[0124] The main core components of the separation and unlocking assembly 100 are the split nut 2, the roller 3 and the nut bracket 4. The specific working principle is as follows:

[0125] In the pre-tightened state, the pre-tightening rope 10 overcomes the elastic potential energy of the drive spring 5, and the nut bracket 4 squeezes the split nut 2 along the X direction through the roller 3. The split nut 2 is in a locked state, and the pressure rod can be normally locked with the split nut 2. When unlocking, the pre-tightening rope 10 is cut by the cutter 9, and the drive spring 5 drives the nut bracket 4 along the Y axis, from the locked state to the unlocked state. The roller 5 moves and falls into the arc-shaped roller unlocking groove 401. After being in the locked state, the separation spring 6 drives the two split nuts 2 to separate along the X axis, and the split nuts 2 are converted from the locked state to the unlocked state, performing the separation and unlocking function.

[0126] Splitting nuts means cutting and dividing the complete nut into multiple pieces, e.g. Figure 1 The two lobes shown, each lobe unit, is called a split-lobe nut 2, and currently commonly used forms include two-lobe type, three-lobe type, and four-lobe type.

[0127] For the complete split nut 2, the more petals there are, the smaller the minimum radial expansion displacement of the separation nut required for release, and the easier it is to release the connecting bolt (i.e., the clamping rod). The fewer petals there are, the better the expansion synchronization and load distribution uniformity. The two-petal split nut has good opening synchronization and load distribution uniformity, but the minimum radial expansion displacement required for release is large. In order to make the two-petal split nut have both good opening synchronization and smaller minimum expansion displacement, the design is carried out by replacing the complete separation nut with a two-petal incomplete separation nut that engages with the bolt thread to bear the load.

[0128] The two-piece incomplete split nut is composed of two square block-shaped split nuts 2, with a portion of the width cut off in the middle.

[0129] The middle of the two split nuts 2 encloses a threaded hole.

[0130] The nut bracket 4 is preferably in a square frame shape.

[0131] Two rollers 3 are installed correspondingly to each split nut 2 .

[0132] The rollers 3 are arranged along the Y-axis direction.

[0133] Due to the working characteristics of the trigger assembly 200, the separation unlocking assembly 100 selects the in-line unlocking method, so the unlocking path of the two-petal separation nut needs to be orthogonal to the movement direction of the driving unlocking component. Figure 2 , the separation nut needs to move along the X direction and be constrained along the Y direction; at the same time, as a driving component, the nut bracket 4 moves in the Y direction and is constrained along the X direction. The movement of the two needs to be transmitted through the rotor, so a roller 3 is set between the nut bracket 4 and the split nut 2. The installation of the roller 3 requires that a semicircular groove for accommodating the roller 3 be set on the nut bracket 4 and the split nut 2 respectively, that is, Figure 1、 2 The roller mounting groove 201 and roller unlocking groove 401 are shown. In the compressed state, the roller 3 is located within the roller mounting groove 201 of the separation nut, while avoiding contact with the inner sidewall of the frame of the nut bracket 4 and avoiding contact with the roller unlocking groove 401 of the nut bracket 4, maintaining compression. During unlocking, after the nut bracket 4 moves into position along the Y axis, the roller unlocking groove 401 on the nut bracket 4 aligns with the roller mounting groove 201 of the separation nut, forming a roller groove into which the roller 3 can fully fall. This allows the separation nut to move in the X direction, and the split nut 2 is pushed apart by the separation spring 6, achieving the unlocking effect.

[0134] During the design process, the split nut was specifically designed in detail, and the thread stress analysis was carried out based on the stress conditions of the complete nut thread: the deformation δ1 caused by the bending of the thread teeth, the deformation δ2 caused by the shear force of the thread teeth, the deformation δ3 caused by the tilting of the thread teeth, the deformation δ4 caused by the shear deformation of the thread teeth, and the deformation δ5 caused by the radial force of the thread teeth were considered;

[0135] 1) Deformation caused by thread bending δ1

[0136] Decompose the normal pressure ω per unit width into the vertical component ωcosα and the horizontal component ωsinα, producing Figure 4 The deformation shown by the dotted line is:

[0137]

[0138] Where ν is the Poisson's ratio of the bolt or nut;

[0139] a——thread root width;

[0140] b——the width of the thread pitch diameter;

[0141] c – the height from the mean diameter of the thread to the root of the thread;

[0142] E——elastic modulus.

[0143] 2) Deformation of thread caused by shear force δ2

[0144] The deformation caused by shear force is as follows Figure 4 As shown in a), the deformation is:

[0145]

[0146] 3) Deformation δ3 caused by the inclination of the thread root

[0147] The pressure acting on the thread diameter will cause the bottom surface of the thread root to tilt, such as Figure 4As shown by the dotted line in b), the inclination of the root causes the deformation of the force application point to be:

[0148]

[0149] 1) Deformation δ4 caused by shear deformation of the thread root

[0150] Assuming that the shear stress in the cross section of the thread root is uniformly distributed, the displacement of point O in the X direction caused by shear deformation is obtained as follows: Figure 4 As shown in c), the displacement of the force application point is consistent with the displacement of the thread in the X direction, so:

[0151]

[0152] Where p is the thread pitch.

[0153] 2) Deformation of thread caused by radial force δ5

[0154] Under the action of horizontal force, the thread diameter causes radial contraction of external thread and radial expansion of internal thread, such as Figure 4 As shown in (d), the deformation amounts are:

[0155]

[0156]

[0157] Where δ 5b ——Deformation of bolt thread along radial contraction;

[0158] δ 5n ——Deformation of the nut thread along the radial expansion;

[0159] d p —effective diameter of the bolt thread;

[0160] D——Nominal diameter of nut thread;

[0161] ν b —Poisson’s ratio of the bolt material;

[0162] ν n ——Poisson’s ratio of the nut material.

[0163] In summary, the total deformation of the bolt and nut threads are

[0164]

[0165] Where k b ——Bolt thread elastic deformation parameter item;

[0166] k n——Parameter item of elastic deformation of nut thread;

[0167] E b —Elastic modulus of bolt material;

[0168] E n ——Elastic modulus of nut material.

[0169] The vertical component of force ωcosα on the thread is the axial force dF(x) acting between x and x+dx.

[0170]

[0171] Where β is the thread lead angle.

[0172]

[0173] Where d2 is the thread diameter.

[0174] For the engagement of bolt and nut threads, the total load Fz, considering that both the bolt and the nut are under tension, is taken as the origin where the bolt and the nut initially contact the threads (the starting point of the first thread circle), as follows: Figure 5 As shown in the figure, at x, the force acting on the vertical surface of the bolt is F(x), then the bolt elongation Δb and the nut elongation Δn at x are respectively

[0175]

[0176]

[0177] Where A b ——bolt cross-sectional area;

[0178] A n ——Cross-sectional area of ​​nut.

[0179] According to the load-bearing conditions, the deformation coordination relationship is:

[0180] (Δ b -Δ n ) x＝x =(δ b +δ n ) x＝x -(δ b +δ n ) x＝0 (1-11)

[0181] Substitute equations (1-7), (1-9) and (1-10) into equation (1-11) and differentiate with respect to x to obtain

[0182]

[0183] in:

[0184]

[0185] The general solution is derived from equation (1-12) as:

[0186] F(x) = C1coshλx + C2sinhλx (1-13)

[0187] From the boundary conditions:

[0188] [F(x)] x＝0 = 0, [F(x)] x＝L = F z

[0189] We get:

[0190]

[0191] Substituting the above equation into equation (1-8), we get

[0192]

[0193] Integrating equation (1-15) with respect to x, we can get the load Z borne by one turn of the thread i

[0194]

[0195] Where i is the i-th turn of the thread;

[0196] p is the thread pitch.

[0197] Taking M4x0.7 thread size as an example, the load distribution at the thread of the screw and nut is shown in the following table:

[0198] Table 1 Load distribution at the thread of the screw and nut

[0199]

[0200] Based on the analysis of the force on the complete nut, the detailed design and analysis of the two-part non-integral split nut are as follows:

[0201] The width s of the middle cutout section of the two-part non-integral split nut affects the minimum radial displacement of the split nut when the bolt is released and the load borne by each turn of the thread. The structure of the two-part non-integral split nut is shown in Figure 7 , where the nominal diameter of the split nut is D, the width of the cutout section is s, and the thread distribution range angle is Φ.

[0202] When the thread is loaded, the thread teeth are mainly subjected to shear stress and bending stress. Considering the strength of the bolt thread teeth, it is only necessary to verify the strength of the thread root. Therefore, for the load-bearing situation of the incomplete separation nut and bolt thread engagement, it is only necessary to verify the shear stress and bending stress of the dangerous thread segment. From the previous section, it can be seen that for the load-bearing of the complete nut and bolt thread engagement, the last circle of thread has the largest load-bearing ratio. Corresponding to the load-bearing of the two-piece incomplete separation nut and bolt engagement, it can be inferred that: the thread load-bearing ratio of the last two and a half circles is the largest (approximately equal), and the maximum load-bearing load F of the last two and a half circles of thread is a for

[0203]

[0204] Where n is the last thread number.

[0205] The shear stress τ of the dangerous section of the thread is

[0206]

[0207] Where d1 is the bolt thread diameter;

[0208] B - the thickness of the bolt thread root, for triangular thread B = 0.75p;

[0209] φ = arccos (s / D) - thread distribution angle unit is rad.

[0210] Bending stress σ of the dangerous section of the thread b for

[0211]

[0212] Where h is the working height of the thread.

[0213]

[0214] Where d is the nominal diameter of the bolt.

[0215] Taking the M4×0.7 split nut with 10 engagement circles as an example, the relationship between the width s of the cut section of the two-petal split nut and the stress of the dangerous section of the thread tooth is shown in Figure 8 As the width of the cut-off section of the split nut increases, the bending stress and shear stress of the dangerous section of the thread gradually increase. The maximum thread bending stress and shear stress can be used to determine the load-bearing capacity of the incomplete split nut thread.

[0216] Taking the nut cutting width s into consideration, the thread strength is taken as an example. Taking the nut cutting width s as (1±0.1) mm, the corresponding shear stress τ of the dangerous section of the thread tooth is: 30.539MPa~31.760MPa; the shear stress τ of the dangerous section of the thread tooth is: 132.238MPa~137.523Mpa. It is appropriate to choose common metal materials such as 45# steel or TC4 titanium alloy as the material of the split nut.

[0217] The locking and releasing device based on the separation nut and the spacecraft provided by the present invention have the following advantages:

[0218] (1) Low impact when unlocking: The triggering method of the present invention mainly adopts the method of cutting the pre-tensioning rope by the cutter. The pre-tensioning rope is in the pre-tensioned state, which keeps the separation component in the pre-tensioned state. The cutter is powered and heated, and after cutting the pre-tensioning rope, the separation component is triggered to work. In this process, the pyrotechnic device is eliminated. During operation, the mechanical impact generated by the movement of the internal trigger spring and the drive spring is much lower than the explosion impact generated by the pyrotechnic device.

[0219] (2) High safety. The trigger components mainly used in the present invention include a cutter, a pre-tightening rope, a spring and an aluminum alloy metal structure. The separation and unlocking mechanism includes a spring and a metal structure. There are no dangerous goods. The products are all enclosed inside the shell. No extra objects will fly out during the movement of the mechanism, and the safety is relatively high.

[0220] (3) Small space occupation: the overall size of the present invention is 120mm×60mm×20mm, which is greatly reduced compared with the solar wing unlocking mechanism of traditional pyrotechnics.

[0221] (4) The installation interface is simple. The external mechanical interface of the present invention adopts a 4-Φ3.2 through hole as the installation interface, and a 1-M4 threaded hole is used as the connection interface between the locking release device and the clamping rod. During the installation process, the force is measured and tightened according to the commonly used torque, eliminating the corresponding calibration clamping force adjustment process.

[0222] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A locking and releasing device based on a separating nut, characterized in that: The invention comprises a shell, a separation and unlocking assembly and a trigger assembly, wherein the separation and unlocking assembly comprises a separation nut, a roller and a nut bracket for locking the pressing rod, the nut bracket and the shell slidingly cooperate along the Y-axis direction, the nut bracket having a separation nut mounting cavity, the separation nut being mounted within the separation nut mounting cavity, the separation nut being composed of at least two split nuts, the split nut being provided with a roller mounting groove, the roller being arranged on the roller mounting groove, the roller being clamped between the nut bracket and the split nut, the inner side surface of the nut bracket being provided with at least a partial roller unlocking groove capable of accommodating the roller, the trigger assembly being connected to the nut bracket, and a separation spring for driving the separation thereof being clamped between the split nuts; When locked, the roller is located outside the roller unlocking groove, and the split nut is kept intact under the support of the roller and locks the clamping rod, that is, the clamping rod is threadedly connected to the separation nut as a screw, and the nut bracket is located in the locked position under the restraint of the trigger assembly; When locked, under the support of the roller, there is a gap between the split nut and the inner side surface of the nut bracket and they remain non-contact; When unlocking, the trigger assembly releases the constraint on the nut bracket, and the nut bracket slides along the Y-axis to reach the unlocking position. The roller falls into the roller unlocking groove, and the split nut loses the support of the roller and disperses, no longer maintaining a complete state, but is in a split state, and loses the lock on the clamping rod, thereby completing the unlocking.

2. The locking and releasing device based on the separation nut according to claim 1, characterized in that: The trigger assembly includes a pre-tensioning rope, a pre-tensioning assembly for keeping the pre-tensioning rope in a tensioned state, and a cutter for cutting the pre-tensioning rope when unlocking. The separation and unlocking assembly also includes a driving spring for driving the nut bracket from a locked position to an unlocked position. One end of the pre-tensioning rope is connected to the nut bracket, and the other end is connected to the pre-tensioning assembly. Under the action of the pre-tensioning rope, the driving spring is clamped between the nut bracket and the housing.

3. The locking and releasing device based on the separation nut according to claim 2, characterized in that: The pre-tightening assembly includes a base, an anti-loosening spring capable of keeping the pre-tightening rope in a pre-tightened state for a long time, a pressing sleeve, an adjustment screw and a sheath capable of adjusting the pre-tightening force of the pre-tightening rope. The base is fixed on the shell, and the pre-tightening rope passes through the base, the anti-loosening spring, the pressing sleeve in sequence and is connected to the adjustment screw. The sheath is fixedly connected to the base, the anti-loosening spring is clamped between the base and the pressing sleeve, the adjustment screw is threadedly connected to the sheath, and the adjustment screw is pressed against the pressing sleeve.

4. The locking and releasing device based on the separation nut according to claim 2, characterized in that: The pre-tightening rope is connected to the nut bracket through a set screw, and the cutter adopts a resistance wire type double-layer hot knife.

5. The locking and releasing device based on the separation nut according to claim 1, characterized in that: The separation nut adopts a two-petal incomplete separation nut with part of the width cut off in the middle, and the width of the cut section is s. The roller constrains the split nut in the X direction. The separation nut mounting cavity is square, with the Y-axis direction as its long side and the X-axis direction as its short side.

6. The locking and releasing device based on the separation nut according to claim 1, characterized in that: The analysis of thread stress is carried out based on the stress condition of the complete nut thread as follows: The calculation formulas for the deformation δ1 caused by thread bending, the deformation δ2 caused by shear force on the thread, the deformation δ3 caused by the tilt of the thread root, the deformation δ4 caused by shear deformation of the thread root, and the deformation δ5 caused by radial force on the thread are as follows: 1) Deformation caused by thread bending δ1 Decompose the normal pressure ω per unit width into the vertical component ωcosα and the horizontal component ωsinα, and the deformation is: Where ν is the Poisson's ratio of the bolt or nut; a——thread root width; b——the width of the thread pitch diameter; c – the height from the mean diameter of the thread to the root of the thread; E——elastic modulus; 2) Deformation of thread caused by shear force δ2 3) Deformation δ3 caused by the inclination of the thread root 4) Deformation δ4 caused by shear deformation of the thread root Where p is the thread pitch; 5) Deformation of thread caused by radial force δ5 Where δ 5b ——Deformation of bolt thread along radial contraction; δ 5n ——Deformation of the nut thread along the radial expansion; d p —effective diameter of the bolt thread; D——Nominal diameter of nut thread; ν b —Poisson’s ratio of the bolt material; ν n — Poisson’s ratio of the nut material; In summary, the total deformation of the bolt and nut threads are Where k b ——Bolt thread elastic deformation parameter item; k n ——Parameter item of elastic deformation of nut thread; E b —Elastic modulus of bolt material; E n ——Elastic modulus of nut material; The vertical component of force ωcosα on the thread is the axial force dF(x) acting between x and x+dx. Where β is the thread lead angle; Where d2 is the thread diameter; For the engagement of the bolt and nut threads, the total load Fz, considering that both the bolt and the nut are under tension, the initial contact point between the bolt and the nut is taken as the origin, that is, the starting point of the first thread circle. At x, the force acting on the vertical surface of the bolt is F(x), then the bolt elongation Δb and the nut elongation Δn at x are respectively Where A b ——bolt cross-sectional area; A n ——cross-sectional area of ​​the nut; According to the load-bearing conditions, the deformation coordination relationship is (Δ b -Δ n ) x＝x =(δ b +δ n ) x＝x -(δ b +δ n ) x＝0 (1-11) Substitute equations (1-7), (1-9) and (1-10) into equation (1-11) and differentiate with respect to x to obtain in: The general solution obtained from formula (1-12) is: F(x)=C1coshλx+C2sinhλx (1-13) According to the boundary conditions: [F(x)] x＝0 =0,[F(x)] x＝L =F z It turns out that: Substituting the above formula into formula (1-8), we get By performing definite integration on equation (1-15), we can find the load Z borne by one circle of thread. i Where i is the i-th thread; p—thread pitch.

7. The locking and releasing device based on the separation nut according to claim 6, characterized in that: Based on the analysis of the stress conditions of the complete nut, the detailed design and analysis of the two-piece incomplete split nut are as follows: For a two-piece, incomplete split nut, the width s of the middle cutout section affects the minimum radial displacement of the split nut when the bolt is released, as well as the load conditions of each thread circle. The nominal diameter of the two-piece incomplete split nut is D, the width of the cut-off section is s, and the thread distribution angle is Φ; When the thread is loaded, the thread teeth are mainly subjected to shear stress and bending stress. Considering the strength of the bolt thread teeth, it is only necessary to verify the strength of the thread root. Therefore, for the load-bearing situation of the incomplete separation nut and bolt thread meshing, it is only necessary to check the shear stress and bending stress of the dangerous thread segment; for the load-bearing situation of the complete nut and bolt thread meshing, the last circle of thread has the largest load-bearing ratio. Corresponding to the load-bearing situation of the two-petal incomplete separation nut and bolt meshing, it can be inferred that the thread load-bearing ratio of the last two and a half circles is the largest, and the maximum load-bearing load of the last two and a half circles of thread is F. a for Where n is the last thread number; The shear stress τ of the dangerous section of the thread is Where d1 is the bolt thread diameter; B - the thickness of the bolt thread root, for triangular thread B = 0.75p; φ=arccos(s / D)—thread distribution angle unit is rad; Bending stress σ of the dangerous section of the thread b for Where h is the working height of the thread; Where d is the nominal diameter of the bolt.

8. A spacecraft, characterized in that: The invention comprises a locking and releasing device based on a separation nut as claimed in any one of claims 1 to 7.

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