Central tube group for retraining equipment and dumbbell using central tube group

Abstract

The invention discloses a central tube set for retraining equipment and a dumbbell using the central tube set, the central tube set and a disc are axially locked through a self-locking block embedded in the surface of a shaft tube, the requirement for the disc is low, and a standard dumbbell disc can be used for assembling; meanwhile, the design of the self-locking block replaces a tailstock assembly structure and is not framed by a tailstock space any more, and discs of different sizes and weights can be assembled and flexibly expanded; the self-locking block is controlled by the locking swing arm mechanism to be axially locked and released, two swing arms of the locking swing arm mechanism can swing between a collinear dead point position and a parallel position under the driving of the unlocking sliding handle, a geometric locking scheme is provided, when one point of two swing arms swing to the collinear dead point position, the mechanism enters a self-stabilizing state, and the self-locking function is achieved. Driving force such as a spring is not needed to maintain stability, even if the self-locking block is extruded from outside to inside, the self-locking block cannot be driven inwards, and the anti-interference performance and the locking reliability are extremely good.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sports equipment, in particular to a center tube group for weight training equipment and a dumbbell using the same. BACKGROUND

[0002] In the technical field of adjustable weight dumbbells, a quick and reliable locking and releasing mechanism of the weight plates is crucial. A representative patent document in the prior art, such as Chinese Patent Publication No. CN212347552U, discloses a weight plate locking mechanism of a dumbbell, which specifically realizes the increase and decrease of the number of assembled weight plates and quick locking through a tail rack assembly and a specially shaped dumbbell weight plate. A fixed hole is formed in the middle of the weight plate, and an open slot is provided at the upper end of the fixed hole. The width of the open slot is smaller than the diameter of the sliding member but larger than the diameter of the fixed shaft, so as to realize the axial positioning of the sliding member after insertion.

[0003] However, through market practice, it is found that such adjustable weight dumbbells have the following deficiencies: (1) due to the special shape of the dumbbell weight plate, the open slot destroys the axial symmetry of the weight plate, so that the center of mass is no longer located at the geometric center. When the dumbbell is rapidly swung, the unbalanced mass distribution will generate additional centrifugal force and vibration, which will bring an obvious "whipping" feeling to the user, increasing the risk of dropping and muscle strain; (2) the tail rack assembly is a sleeve structure with a fixed length, and the size of the space for assembly and the axial accommodation limit the upper limit of the diameter and number of the assembled weight plates, which makes the maximum adjustable weight of the dumbbell be fixed by the mechanical structure at the beginning of the design, and it is impossible to achieve flexible expansion by simply increasing the length of the shaft tube. SUMMARY

[0004] The present application aims to provide a center tube group for weight training equipment and a dumbbell using the same to solve the above technical problems. The present application can quickly and reliably realize the mounting and axial locking of the weight plates while still using standard dumbbell weight plates without gaps, ensuring that the center of mass is strictly located at the center of the weight plate, and providing a stable and smooth movement trajectory. At the same time, the self-locking block on the shaft tube axially locks the weight plate, so that the maximum adjustable weight is not limited by the mechanical structure of the tail rack assembly, and the purpose of expanding the maximum adjustable weight can be achieved more flexibly.

[0005] To solve the above technical problems, the present application adopts the following technical solutions:

[0006] A center tube group for weight training equipment, comprising two shaft tubes arranged in line along the same axis, the two shaft tubes being axially displaceable relative to each other, the shaft tubes being provided with at least one set of radially opposite self-locking blocks, the self-locking blocks being movably embedded in the surface of the shaft tubes and being radially extendable and retractable relative to the surface of the shaft tubes.

[0007] The shaft tube is provided with an unlocking handle which can slide along the axial direction of the shaft tube;

[0008] Each set of self-locking blocks is linked with a set of locking swing arm mechanisms, the locking swing arm mechanisms include two radially opposite swing arms, and the unlocking handle drives the self-locking blocks through the locking swing arm mechanisms;

[0009] One end of the swing arm is movably connected to the self-locking block, and the other end is movably connected to the unlocking handle, and the axial sliding of the unlocking handle can drive the two swing arms to swing between the collinear dead point position and the parallel position, when the two swing arms are at the collinear dead point position, the axes of the two swing arms are collinear with the radial extension direction of the self-locking block, and the self-locking block protrudes from the surface of the shaft tube, and the self-locking block in this state will not be pressed from the outside to be retracted.

[0010] By adopting the above technical scheme, the two shaft tubes with axial relative displacement can realize the switching of the number of mounted plates through extension and retraction, and the relative extension and retraction of the two shaft tubes can ensure that the number of plates on both sides is increased or decreased synchronously, thereby ensuring the balance of the dumbbell weight; at least one set of self-locking blocks embedded in the surface of the shaft tube are used to cooperate with the plates to realize axial locking, which has very low requirements for the plates, can use standard and gap-free dumbbell plates, ensures that the mass center of the plate is located at the center of the plate, can provide stable and smooth motion trajectory, and reduces the risk of motion injury; at the same time, the design of the self-locking blocks replaces the tail frame assembly, so that the maximum adjustable weight of the dumbbell is no longer limited by the space type mechanical structure of the tail frame, and the maximum mounting number only depends on the length of the shaft tube, so that the maximum weight can be easily expanded by increasing the extension length of the shaft tube, and the flexibility of the design and upgrade is higher; in addition, it is worth noting that the self-locking blocks are retracted on the surface of the shaft tube under the linkage and driving of the unlocking handle and the locking swing arm mechanism to realize the axial locking and release of the control plates, and the two swing arms of the locking swing arm mechanism swing between the collinear dead point position and the parallel position under the driving of the unlocking handle, that is, the locking swing arm mechanism provides a geometric locking scheme, once the two swing arms swing to the collinear dead point position, the axis at that time forms a collinear with the radial extension direction of the self-locking block, and the mechanism enters a self-stabilizing state without any spring, electromagnet or other continuous driving force to maintain locking, which eliminates the possibility of accidental unlocking caused by power failure, external vibration or accidental touch from the physical principle, the self-locking blocks are locked by the two swing arms at the collinear dead point position, and even if the self-locking blocks are pressed from the outside to the inside, they will not be driven inward, and have excellent anti-interference and locking reliability.

[0011] Further, the unlocking handle is provided with a vertical guide groove, a guide pin is movably penetrated in the vertical guide groove in horizontal direction, and the guide pin is movable along the slot hole of the vertical guide groove.

[0012] By using the above technical scheme, when the guide pin is applied with a vertical driving force, the guide pin can only slide in the oblique direction along the slot hole of the oblique guide groove under the constraint of the slot hole, and the guide pin must drive the unlocking handle to perform the pulling movement, therefore, the unlocking handle is provided with a vertical guide groove, the guide pin is slidably penetrated in the slot hole of the vertical guide groove, so that the guide pin is axially pulled on the unlocking handle while the vertical constraint between the guide pin and the unlocking handle is released; that is, the vertical driving force applied on the guide pin is converted into the final driving force for sliding the unlocking handle in the axial direction under the cooperation of the oblique guide groove and the vertical guide groove.

[0013] Further, one end of the unlocking handle is provided with a first return spring, and the first return spring is used for elastically returning the unlocking handle after the sliding.

[0014] By using the above technical scheme, the first return spring can be compressed to store the force when the unlocking handle is pulled back, and then the first return spring is used for elastically returning the unlocking handle.

[0015] Further, the self-locking block is provided with a button assembly, the button assembly is provided with a linkage arm, the linkage arm is connected between the button assembly and the guide pin, and the linkage arm is used for transmitting the driving force of the button assembly to the guide pin.

[0016] By using the above technical scheme, the linkage arm is used as a transmission medium to transmit the driving force input by the button assembly to the guide pin, and the space layout of the product is optimized, so that the button assembly can be arranged at a more suitable position.

[0017] Further, the linkage arm is provided with a horizontal translation sliding groove, the length of the translation sliding groove is adapted to the displacement stroke length of the shaft tube, the guide pin is penetrated in the translation sliding groove, and the guide pin is slidable along the slot hole of the translation sliding groove.

[0018] By using the above technical scheme, the guide pin can be translated with the shaft tube, and therefore the guide pin cannot be fixedly connected to the linkage arm, the translation sliding groove is arranged on the linkage arm and adapted to the displacement stroke length of the shaft tube, so that the linkage arm and the guide pin can be connected while the guide pin can be translated with the shaft tube.

[0019] A dumbbell using any of the above center tube groups, comprising a handle sleeved on the center tube group, the handle is connected with end pivot structures at both ends, the handle is equivalent to the end pivot structures at both ends to realize rotation; two shaft tubes are respectively provided with sliding keys, the inclination angles of the two sliding keys are mirror-symmetric; the handle is formed with interlaced double thread, and the thread is respectively engaged with the two sliding keys.

[0020] By adopting the above technical scheme, the handle rotates relative to the end pivot structures at both ends, since the thread in the handle is interlaced double thread and is engaged with the mirror-symmetric sliding keys on the two shaft tubes, this makes one rotation direction of the handle drive the two shaft tubes to synchronously extend towards each other, and the other rotation direction drives them to synchronously retract away from each other, the whole process always ensures that the weight center of gravity is located in the middle of the handle, thus ensuring that the dumbbell is balanced during weight adjustment and use, and one rotation can realize the weight adjustment to keep both sides balanced, which improves the convenience of operation.

[0021] Further, the self-locking block is provided with a button assembly, the button assembly is arranged in the end pivot structure, the shell of the end pivot structure is provided with an operation window, the button assembly corresponds to the operation window and interacts with the outside through the operation window.

[0022] By adopting the above technical scheme, the user can operate the button assembly through the operation window by using a thimble, pressing and the like.

[0023] Further, the self-locking block is provided with a button assembly, the button assembly is arranged in the end pivot structure, the end pivot structure is provided with a locking disc coaxially rotating with the handle, the circumferential direction of the locking disc is provided with at least one locking groove, the button assembly is fixedly connected with a locking pin, the locking pin can be matched and clamped into the locking groove in the reciprocating stroke of the button assembly, and the clamping of the locking pin into the locking groove limits the rotation of the locking disc.

[0024] By adopting the above technical scheme, the locking disc coaxially rotates with the handle, the locking groove is in the stroke range of the reciprocating movement of the locking pin with the button assembly, thus when the button assembly is not pressed, the locking pin is clamped into the locking groove, the locking disc is locked, so that the handle cannot rotate, only when the button is pressed, the locking pin will be out of the locking groove, realizing the unlocking of the handle, thus further locking the weight adjustment of the dumbbell, improving the safety of the product.

[0025] Further, the self-locking block is provided with a button assembly, the button assembly is arranged in the end pivot structure, the shell of the end pivot structure is provided with an observation window, the inside of the end pivot structure corresponding to the observation window is provided with an arc-shaped groove, the arc-shaped groove is provided with a swing block swingable in the stroke range of the arc-shaped groove, one end of the swing block is movably connected to the button assembly, the reciprocating movement of the button assembly drives the swing block to swing left and right in the arc-shaped groove, the size of the observation window is adapted to each swing stable position of the swing block.

[0026] By adopting the technical scheme, the unlocking / locking mark can be arranged on the swing block, the swing block swings left and right in the arc-shaped groove along with the pressing and rising of the button assembly, and the size of the observation window is just adapted to each swing stable position of the swing block, so that the unlocking mark can be displayed in the observation window when the button assembly is pressed, and the swing block swings to the other side to display the locking mark in the observation window when the button assembly is raised.

[0027] Further, the dumbbell comprises a disc movably connected to the central pipe group, the disc is axially provided with an assembly hole corresponding to the shaft pipe, and an inner groove is formed on the inner wall of the assembly hole, the position of the inner groove corresponds to the position of the self-locking block in the extended state, and the inner groove can cooperate with the self-locking block in the extended state to axially limit the disc.

[0028] By adopting the technical scheme, the inner groove is arranged in the assembly hole of the disc, and the self-locking block is correspondingly arranged to axially lock the disc, so that the change of the standard disc is simple, without the need of designing complex accessories, the production cost can be reduced, the expansion flexibility of the disc is higher, the disc is only needed to be simply modified in the assembly hole, the disc is not easy to loosen and fall off due to the rigid mechanical interlocking structure of the inner groove and the self-locking block, the multiple discs are stacked, the outermost disc is locked by the inner groove and the self-locking block, there is no looseness gap between the multiple discs, the dumbbell is improved in integrity, and no collision noise occurs in the use process.

[0029] Further, the assembly hole is a polygonal hole.

[0030] By adopting the technical scheme, the polygonal hole and the corresponding cross section on the shaft pipe can form a face contact type anti-torsion structure, so that the disc is prevented from rotating circumferentially on the shaft pipe, and the integrity and stability of the dumbbell are improved.

[0031] Further, the dumbbell comprises a placing base for placing the dumbbell, a jacking rod is arranged on the placing base, the self-locking block is provided with a button assembly, and the button assembly corresponds to the jacking rod.

[0032] By adopting the technical scheme, the user can operate the button assembly without manually pressing, and only needs to place the dumbbell on the base, so that the jacking rod can accurately jack the button assembly, and then trigger the self-locking block to retract to realize unlocking.

[0033] The present application has the following beneficial effects due to the adoption of the above technical scheme:

[0034] 1. The present application has low requirements for the disc, can use standard and non-intercepted dumbbell discs, ensures that the mass center of the disc is located at the center of the disc, can provide a stable and smooth motion trajectory, and reduces the risk of motion injury.

[0035] 2、The self-locking block design replaces the tailstock assembly, so the maximum adjustable weight of the dumbbell is no longer limited by the tailstock space type mechanical structure, and the maximum loading quantity only depends on the length of the shaft tube, so that the maximum weight can be easily expanded by only increasing the telescopic length of the shaft tube, and the design and upgrading flexibility is higher;

[0036] 3、The locking swing arm mechanism provides a geometric locking scheme, once the swing arm swings to the collinear dead point position, the mechanism enters a self-stabilizing state, without any spring, electromagnet and other continuous driving force to maintain locking, the self-locking block is locked by the two swing arms at the collinear dead point position, even if the self-locking block is extruded from outside to inside, it will not be driven inward, and has excellent anti-interference and locking reliability. BRIEF DESCRIPTION OF DRAWINGS

[0037] The application will be further described below in combination with the drawings:

[0038] Figure 1 It is a structural schematic view of the center tube group of the application;

[0039] Figure 2 It is a structural schematic view of the center tube group in a bird's eye view state;

[0040] Figure 3 It is a structural schematic view of Figure 2 the section structure of A-A;

[0041] Figure 4 It is a structural schematic view of the shaft tube inside the center tube group of the application;

[0042] Figure 5 It is a structural schematic view of the shaft tube in the center tube group of the application;

[0043] Figure 6 It is a structural schematic view of the unlocking slide handle in the center tube group of the application;

[0044] Figure 7 It is a structural schematic view of the unlocking slide handle with a slide handle shell in the center tube group of the application;

[0045] Figure 8 It is a structural schematic view of the locking swing arm mechanism in a collinear dead point position of the application;

[0046] Figure 9 It is a structural schematic view of the self-locking block of the application;

[0047] Figure 10 It is a structural schematic view of the linkage arm and the unlocking slide handle in a cooperation state of the application;

[0048] Figure 11 It is a structural schematic view of the center tube group and the button assembly in a cooperation state of the application;

[0049] Figure 12 Structure diagram of the button assembly of the present application;

[0050] Figure 13 Structure diagram of the end pivot structure of the present application from the front view;

[0051] Figure 14 Structure diagram of the end pivot structure of the present application from the back view;

[0052] Figure 15 Structure diagram of the end pivot structure of the present application and the handle in the incomplete assembly state;

[0053] Figure 16 Structure diagram of the end pivot structure of the present application and the handle in the complete assembly state;

[0054] Figure 17 Structure diagram of the placing base of the present application;

[0055] Figure 18 Structure diagram of the disc of the present application;

[0056] Figure 19 Structure diagram of the dumbbell and the placing base of the present application in the combined state;

[0057] Figure 20 Structure diagram of the handle of the present application from the cross-sectional view;

[0058] Figure 21 Structure diagram of the locking swing arm mechanism of the present application in the state of releasing the collinear dead point position;

[0059] In the figure: 1 - central tube group; 11 - shaft tube; 111 - first shaft tube; 112 - second shaft tube; 12 - sliding key groove; 13 - sliding key; 131 - shaft inner tube; 2 - self-locking block; 21 - lock block through hole; 22 - linkage swing arm;

[0060] 3 - unlocking sliding handle; 31 - guide pin; 32 - vertical guide groove; 321 - floating seat; 33 - oblique guide groove; 34 - first return spring; 35 - locking swing arm mechanism; 36 - first swing arm; 37 - second swing arm; 38 - swing arm seat; 4 - linkage arm; 41 - first linkage arm; 42 - second linkage arm; 43 - translation sliding groove; 5 - button assembly; 51 - top contact; 52 - operation window; 53 - linkage arm mounting seat; 54 - second return spring; 55 - guide rib;

[0061] 6 - end pivot structure; 61 - journal; 62 - observation window; 63 - swing block; 64 - driving guide column; 65 - arc-shaped groove; 66 - end pivot front cover; 67 - end pivot rear cover; 7 - handle; 71 - shaft sleeve; 72 - locking disc; 73 - locking groove; 74 - locking pin; 75 - thread;

[0062] 8 - disc; 81 - assembly hole; 82 - inner groove; 9 - placing base; 91 - top rod; 92 - disc slot. DETAILED DESCRIPTION

[0063] It should be noted that the embodiments and features of the embodiments in the present application can be combined with each other without conflict. The technical solutions in the embodiments of the present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0064] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0065] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion.

[0066] Embodiment 1

[0067] A weight-adjustable dumbbell includes a center tube group 1 that can be bidirectionally and synchronously telescoped on an axis, and a handle 7 sleeved outside the center tube group 1, rotation of the handle 7 can drive the center tube group 1 to realize bidirectional and synchronous telescoping; a plurality of discs 8 are arranged at both ends of the dumbbell, when the center tube group 1 that is bidirectionally and synchronously telescoped cooperates with the discs 8 at both ends to increase or decrease, the number of discs 8 must be equal, so as to automatically maintain the perfect balance of the dumbbell.

[0068] In the present embodiment, the center tube group 1 includes two axial collinear shaft tubes 11, which are respectively a first shaft tube 111 and a second shaft tube 112, as shown in Figures 1-3 The two shaft tubes 11 are provided with an axial relative displacement variable stroke, that is, the first shaft tube 111 and the second shaft tube 112 can realize bidirectional and synchronous telescoping on the axis.

[0069] A sliding key 13 with a mirror image inclination angle is arranged on each of the two shaft tubes 11, as shown in Figure 1 、 Figure 2

[0070] Furthermore, the shaft tube 11 is sleeved with an inner shaft tube 131, as shown in Figure 3 、 Figure 4

[0071] The sliding key 13 is formed on the surface of the inner shaft tube 131, as shown in​​Figure 4 、 Figure 7 as shown in FIG. 6;

[0072] The shaft tube 11 is provided with a sliding key groove 12 corresponding to the sliding key 13, as shown in FIG. 6; Figure 5

[0073] The matching state of the two is that the shaft inner tube 131 is sleeved inside the shaft tube 11, and the sliding key 13 extends radially from the sliding key groove 12;

[0074] In this embodiment, the shaft inner tube 131 is inside the shaft tube 11, and the two are in interference fit, and the shaft inner tube 131 moves axially synchronously with the shaft tube 11;

[0075] Since the sliding key 13 extends radially from the sliding key groove 12, the limiting of the two further enables the shaft inner tube 131 to move axially synchronously with the shaft tube 11;

[0076] In this embodiment, the sliding key 13 is integrally formed with the shaft inner tube 131.

[0077] Both ends of the handle 7 are provided with end pivot structures 6, as shown in FIG. 7; Figure 16 The handle 7 rotates relative to the end pivot structures 6 at both ends, that is, the end pivot structures 6 at both ends enable the handle 7 to rotate independently;

[0078] The two rotation directions of the handle 7 respectively control the extension and retraction of the two shaft tubes 11;

[0079] Further, the handle 7 is formed with interlaced double-threaded threads 75 inside, which respectively engage with the two sliding keys 13, and the threads 75 are uniformly distributed inside the handle 7, as shown in FIG. 8;

[0080] Figure 20 Through the cooperation of the threads 75 and the sliding keys 13, the rotation of the handle 7 in one clockwise direction controls the synchronous extension of the two shaft tubes 11 to both ends, and the rotation of the handle 7 in the other clockwise direction controls the synchronous retraction of the two shaft tubes 11 inward.

[0081] In this embodiment, the end pivot structure 6 is composed of an end pivot front cover 66 and an end pivot rear cover 67, as shown in FIG. 9 and FIG. 10;

[0082] The end pivot structure 6 is connected with the handle 7, and is provided with a shaft neck 61 for cooperating with a shaft sleeve 71 to realize stable connection, and the shaft neck 61 is formed on one side of the end pivot front cover 66, as shown in FIG. 11; Figure 11 Figure 15

[0083] The handle 7 is provided with the shaft sleeve 71 at both ends, as shown in FIG. 12 and FIG. 13; Figure 13

[0084] The handle 7 is provided with the shaft sleeve 71 at both ends, as shown in FIG. 12 and FIG. 13; Figure 15 Figure 20 The handle 7 is provided with the shaft sleeve 71 at both ends, as shown in FIG. 12 and FIG. 13;​​​​​​

[0085] When the handle 7 is rotatably connected between the two end pivot structures 6, the shaft neck 61 is inserted and nested in the inner hole of the shaft sleeve 71, and the two are clearance fitted; the shaft neck 61 and the shaft sleeve 71 are cooperatively capable of bearing loads from the radial direction, thereby improving the stability of the connection between the handle 7 and the end pivot structure 6.

[0086] Further, a ball type positioning pin is arranged between the shaft sleeve 71 and the shaft neck 61, a plurality of blind holes are formed on the surface of the shaft neck 61, and elastic members and balls are arranged in the blind holes; the elastic members continuously apply a pre-pressing force to the balls in the outward direction, and the inner wall of the shaft sleeve 71 is provided with corresponding recesses; when the handle 7 is rotated relative to the end pivot structure 6, the balls on the shaft neck 61 will roll on the smooth inner wall of the shaft sleeve 71; when rotated to a specific position, the balls will pop out and cooperate with the recesses to emit a “click” sound, thereby prompting the user to rotate to the position; when the handle 7 is continuously rotated, a certain force can overcome the elastic force of the elastic members, and then the balls will be separated from the recesses and continue to roll on the inner wall of the shaft sleeve 71.

[0087] The end pivot structure 6 is located between the handle 7 and the disc 8, and the shaft tube 11 is extended to the two ends to cooperate with the disc 8 when the handle 7 is rotated, so the shaft tube 11 is an active through hole in the end pivot structure 6 as shown in FIG. 1. Figure 16

[0088] The first shaft tube 111 and the second shaft tube 112 are synchronously extended from the end faces of the end pivot structures 6 at the two ends to hang a certain number of discs 8, and the hanging mode of the shaft tube 11 and the disc 8 is that the shaft axis direction of the shaft tube 11 penetrates the shaft center of the disc 8.

[0089] Further, the shaft center of the disc 8 is provided with an assembly hole 81, and the cross section of the shaft tube 11 is adapted to the assembly hole 81 and can penetrate the assembly hole 81.

[0090] Further, the assembly hole 81 is a polygonal hole.

[0091] The cross section of the shaft tube 11 is matched, the shaft tube 11 is inserted into the polygonal hole, and the relative rotation between the shaft tube 11 and the assembly hole 81 is naturally limited by the polygonal cooperation; thereby the disc 8 and the central tube group 1 are circumferentially positioned, and the shaking of the dumbbell caused by the rotation of the disc 8 in use is avoided.

[0092] In this embodiment, the assembly hole 81 is a quadrangular hole as shown in FIG. 2. Figure 18

[0093] In this embodiment, the inner wall of the assembly hole 81 is radially formed with an inner groove 82 as shown in FIG. 3. Figure 18

[0094] In order to meet the requirements of hanging the disc 8 while being axially stable, in this embodiment, the central tube group 1 is provided with at least one set of radially opposite self-locking blocks 2.

[0095] ​​​Specifically, in this embodiment, each shaft tube 11 has a pair of radially opposing self-locking blocks 2 at one end, such as... Figure 1 , Figure 3 As shown;

[0096] The surface of the shaft tube 11 is symmetrically provided with locking block through holes 21, such as Figure 5 As shown;

[0097] The self-locking block 2 is movably embedded in the surface of the shaft tube 11, that is, the self-locking block 2 can extend out of the surface of the shaft tube 11 through the locking block through hole 21, or it can be retracted into the shaft tube 11.

[0098] When the first shaft tube 111 and the second shaft tube 112 each pass through the end pivot structure 6 and are mounted on the discs 8 at both ends:

[0099] After the first shaft tube 111 and the second shaft tube 112 extend out, they are each mounted with the same number of disks 8 at both ends; according to Figure 1 As shown, the self-locking block 2 is located at one end of the two shaft tubes 11 that are far apart from each other. It will be referred to as the outermost end of the shaft tube 11 in the following text. That is, no matter how many disks 8 are mounted on the shaft tube 11, the self-locking block 2 located at the outermost end of the shaft tube 11 will correspond to the inner groove 82 of the outermost disk 8 on the shaft tube 11. After the self-locking block 2 extends out of the surface of the shaft tube 11, it is inserted into the inner groove 82 of the outermost disk 8, and thus achieves axial locking with the outermost disk 8. Since the self-locking block 2 is located at the outermost end of the shaft tube 11, its axial locking with the outermost disk 8 also axially locks all the disks 8 between the outermost disk 8 and the end pivot structure 6.

[0100] The outermost end of the shaft tube 11 is provided with at least one set of radially opposed self-locking blocks 2 for cooperating with the disc 8 to achieve axial locking. Compared with existing dumbbells with quick weight adjustment, the requirements for the disc 8 are lower, and standard, unnotch-free discs 8 can be used, ensuring that the center of mass of the disc 8 is located at the center of the disc 8. At the same time, the design of the self-locking block 2 replaces the tailstock assembly, and the maximum adjustable weight of the dumbbell is no longer limited by the mechanical structure of the tailstock space. The weight of the dumbbell can be expanded simply by replacing the disc 8 on the shaft tube 11 with a larger and heavier one, or by increasing the telescopic length of the shaft tube 11. This design and upgrade are more flexible.

[0101] The shaft tube 11 is provided with an unlocking slide handle 3, which has a variable stroke that can slide along the axial direction of the shaft tube 11; furthermore, the unlocking slide handle 3 is located inside the shaft tube 11 and can slide axially within the shaft tube 11.

[0102] Each pair of self-locking blocks 2 is linked with a set of locking swing arm mechanisms 35 composed of two diametrically opposed swing arms, the locking swing arm mechanisms 35 are connected between the self-locking blocks 2 and the unlocking slide handle 3, by controlling the axial sliding of the unlocking slide handle 3, the two swing arms of the locking swing arm mechanisms 35 will swing accordingly, and then drive the self-locking blocks 2 to extend or retract.

[0103] In this embodiment, the two diametrically opposed swing arms of the locking swing arm mechanisms 35 are respectively a first swing arm 36 and a second swing arm 37;

[0104] Wherein, one end of each of the first swing arm 36 and the second swing arm 37 is hinged with the upper and lower self-locking blocks 2, and the other end of the two swing arms is connected to the unlocking slide handle 3, as shown in Figure 6 、 Figure 7 ;

[0105] It should be noted that the two swing arms in this application specifically refer to the first swing arm 36 and the second swing arm 37 included in the locking swing arm mechanisms 35;

[0106] Further, the end of the unlocking slide handle 3 is provided with a swing arm seat 38, and the ends of the two swing arms are hinged with the unlocking slide handle 3 through the swing arm seat 38, as shown in Figure 7 、 Figure 8 ;

[0107] The shaft tube 11 is sleeved with an inner shaft tube 131, and the unlocking slide handle 3 is axially sleeved in the inner shaft tube 131, as shown in Figure 6 、 Figure 7 ;

[0108] The self-locking blocks 2 extend to one side of the inner shaft tube 131 and form a linkage swing arm 22, and the self-locking blocks 2 are hinged with the inner shaft tube 131 through the linkage swing arm 22, as shown in Figure 7 ;

[0109] Through the cooperation of the locking swing arm mechanisms 35, the unlocking slide handle 3 and the self-locking blocks 2, the axial reciprocating sliding of the unlocking slide handle 3 realizes the control of the extension and retraction of the self-locking blocks 2, and the specific working principle is as follows:

[0110] The first swing arm 36 and the second swing arm 37 convert their own swing into the radial displacement of the self-locking blocks 2 by being hinged with the self-locking blocks 2; the first swing arm 36 and the second swing arm 37 convert the axial movement of the unlocking slide handle 3 into the swing movement of the two swing arms by being hinged with the unlocking slide handle 3 through the swing arm seat 38; the hinge between the self-locking blocks 2 and the inner shaft tube 131 limits the movement of the self-locking blocks 2 within the stroke range;

[0111] The axial reciprocating movement of the unlocking slide handle 3 can drive the first swing arm 36 and the second swing arm 37 to swing, so that the first swing arm 36 and the second swing arm 37 swing between the collinear dead point position and the parallel position, as shown in Figure 8 、 Figure 21As shown, this causes the self-locking block 2 to reciprocate radially; when the first swing arm 36 and the second swing arm 37 swing to the collinear dead point position under the push of the unlocking slider 3, as shown... Figure 8 As shown, at this time, the self-locking block 2 is fully extended from the surface of the shaft tube 11. In this state, the self-locking block 2 can be inserted into the inner groove 82 of the corresponding disk 8 to axially lock the disk 8.

[0112] When the first swing arm 36 and the second swing arm 37 move to the position shown in the figure Figure 8 When the two swing arms are in the collinear dead position, the self-locking block 2, which is pushed out of the surface of the shaft tube 11 by the two swing arms, provides a geometric locking solution. Compared with existing technologies that require continuous driving force to maintain the locking state, such as locking by spring force or electric drive, the external compressive force applied to the self-locking block 2 is transmitted along the axis of the swing arms and cannot generate an effective torque to rotate the two swing arms. That is, the locking swing arm mechanism 35 provides a geometric locking solution. Once the two swing arms form a collinear dead position, their axis at that time is collinear with the radial extension direction of the self-locking block 2. Figure 8 As shown, the mechanism enters a self-stabilizing state, requiring no continuous driving force from springs, electromagnets, etc. to maintain the lock. This eliminates the possibility of accidental unlocking due to power failure, external vibration, or accidental contact from a physical principle perspective. The self-locking block 2 is locked by two swing arms at collinear dead points. Even if the self-locking block 2 is pressed from the outside to the inside, it will not be driven inward, thus possessing excellent anti-interference and locking reliability.

[0113] The self-locking block 2, which is locked by the collinear dead point position of the first swing arm 36 and the second swing arm 37 and extends out of the shaft tube 11, can only be actively broken by the axial sliding of the unlocking handle 3, causing the two swing arms to swing towards a position approaching parallel. Figure 21 As shown, by releasing the collinear dead point position of the two swing arms, the self-locking block 2 will be driven to retract radially into the shaft tube 11, and the self-locking block 2 and the inner groove 82 will achieve axial unlocking.

[0114] The self-locking block 2 is equipped with a button assembly 5, which can drive the unlocking slider 3 to perform reciprocating axial movement.

[0115] In this embodiment, the button assembly 5 is located within the end pivot structure 6, and it is capable of radial reciprocating motion within the end pivot structure 6;

[0116] Furthermore, the end pivot structure 6 includes a front end pivot cover 66 and a rear end pivot cover 67, such as... Figure 11 , Figure 15 As shown, after the front cover 66 and the rear cover 67 of the end pivot are closed, a cavity space is formed in the middle, and the button assembly 5 is movably disposed in this cavity space.

[0117] In this embodiment, a guide rib 55 is provided on the inner side wall of the end pivot rear cover 67, such as... Figure 11 ,Figure 13 as shown;

[0118] Two guide ribs 55 are symmetrically arranged on the left and right, forming a guide rail structure in the cavity space of the end pivot structure 6, which just accommodates the button assembly 5 and limits its movement track. The button assembly 5 can only move radially and reciprocally within the range of the guide rail;

[0119] The bottom end of the button assembly 5 is formed with a top contact 51, as shown in Figure 12 ;

[0120] The bottom of the end pivot structure 6 is provided with an operation window 52 for operating the button assembly 5, as shown in Figure 13 , the position of the operation window 52 corresponds to the top contact 51;

[0121] The user can touch the top contact 51 through the operation window 52, thereby pushing the button assembly 5 to move upward;

[0122] Above the top contact 51, the button assembly 5 is formed with a linkage arm mounting seat 53, as shown in Figure 12 ;

[0123] The button assembly 5 is provided with a linkage arm 4, which is used for transmission between the button assembly 5 and the unlocking handle 3;

[0124] In this embodiment, the linkage arm 4 is a long strip structure connected to two button assemblies 5 at the same time, as shown in Figure 10 , Figure 11 ; The two button assemblies 5 are respectively connected to the left and right ends of the same linkage arm 4. Only when the two button assemblies 5 move upward at the same time, the linkage arm 4 can be effectively controlled to displace upward;

[0125] In this embodiment, the linkage arm mounting seat 53 is a clamping groove structure matched with the shape of the linkage arm 4, as shown in Figure 12 ; The linkage arm mounting seat 53 is in interference fit with the linkage arm 4.

[0126] The linkage arm 4 displaces upward as the two end button assemblies 5 synchronously lift upward, which can drive the unlocking handle 3 to axially slide;

[0127] The cooperation between the linkage arm 4 and the unlocking handle 3 is as follows:

[0128] The unlocking handle 3 is provided with a vertical guide groove 32, and a guide pin 31 is movably and horizontally inserted into the vertical guide groove 32, as shown in Figure 6 ;

[0129] Specifically, the end of the unlocking handle 3 away from the swing arm seat 38 is provided with a floating seat 321, as shown in Figure 6 ; The floating seat 321 is fixedly connected to the end of the unlocking handle 3, and the vertical guide groove 32 is throughly formed in the floating seat 321.

[0130] The floating seat 321 is slidably connected in the shaft inner tube 131 with the unlocking handle 3, and the shaft inner tube 131 is fixedly sleeved in the shaft tube 11, as shown in the figure. Figures 3-7

[0131] Corresponding transverse through openings are provided with inclined guide grooves 33 on the shaft tube 11 and the shaft inner tube 131, as shown in the figure. Figures 3-5 The shaft inner tube 131 is fixedly positioned with the shaft tube 11, and the two correspondingly provided through inclined guide grooves 33 can be penetrated by the guide pin 31 from both sides of the shaft tube 11.

[0132] The vertical guide groove 32 corresponds to the inclined guide groove 33, and the guide pin 31 can slide along the direction of the groove hole when penetrating the vertical guide groove 32; the guide pin 31 can slide along the direction of the groove hole when penetrating the inclined guide groove 33; the guide pin 31 is simultaneously arranged in the two guide groove structures, and by applying an upward driving force to the guide pin 31, the guide pin 31 will slide obliquely upward along the inclined guide groove 33, so as to Figure 3 For reference, the oblique upward sliding of the guide pin 31 should drive the unlocking handle 3 to slide obliquely upward to the far end side of the locking swing arm mechanism 35, but the unlocking handle 3 is limited by the shaft inner tube 131 and can only slide axially in the shaft inner tube 131; the vertical guide groove 32 provides a longitudinal sliding space for the guide pin 31 and releases the longitudinal constraint of the guide pin 31, that is, the guide pin 31 still slides obliquely upward, but the longitudinal traction force of the guide pin 31 will not be transmitted to the unlocking handle 3, but will be "yielded" by the vertical guide groove 32; thus, the external force driving the guide pin 31 to slide obliquely upward will in turn drive the unlocking handle 3 to slide away from the self-locking block 2; conversely, the guide pin 31 slides obliquely downward, driving the unlocking handle 3 to slide toward the self-locking block 2.

[0133] In the embodiment, the unlocking handle 3 is provided with a first reset spring 34, as shown in the figure. Figure 3 Figure 4

[0134] The first reset spring 34 is sleeved on the unlocking handle 3, one end of which is fixedly connected with the swing arm seat 38, as shown in the figure. Figure 6

[0135] The other end of the first reset spring 34 abuts against the shaft inner tube 131, as shown in the figure. Figure 7

[0136] When the unlocking handle 3 is driven by the guide pin 31 to slide away from the self-locking block 2, the first reset spring 34 between the swing arm seat 38 and the shaft inner tube 131 will be squeezed to accumulate potential energy; when the guide pin 31 loses the driving force to slide obliquely upward, the first reset spring 34 will rebound to push the swing arm seat 38, so that the unlocking handle 3 slides toward the self-locking block 2 again, as shown in the figure. Figure 3 ​​​​​As shown, that is, after the first reset spring 34 rebounds, the unlocking handle 3 is reset to the state that the self-locking block 2 extends out of the shaft tube 11 and is locked in cooperation with the inner groove 82, and the two swing arms are reset to the co-linear dead point position.

[0137] The guide pin 31 transversely penetrates the oblique guide groove 33, and the two ends thereof extend out of the two sides of the shaft tube 11 for connection with the linkage arm 4, as shown in Figure 2 As shown, in the embodiment, the two sides of the shaft tube 11 are each provided with the linkage arm 4;

[0138] Through the transmission of the linkage arms 4 on the two sides to the guide pin 31 simultaneously, the stability of the movement of the guide pin 31 can be improved;

[0139] Each linkage arm 4 on the side is a long strip structure capable of connecting the button assembly 5 at two ends simultaneously, as shown in Figure 1 、 Figure 2 As can be seen, each linkage arm 4 on the side is also capable of connecting with the guide pin 31 provided on the first shaft tube 111 and the second shaft tube 112 simultaneously;

[0140] In this way, when the button assemblies 5 at two ends move upward simultaneously, the linkage arms 4 located at the two sides of the shaft tube 11 are lifted upward, and the linkage arms 4 on the two sides are lifted upward synchronously, which can stably control the guide pin 31 to move obliquely upward, and then the guide pin 31 pulls the unlocking handle 3 to move axially away from the self-locking block 2, thereby realizing the control unlocking of the locking swing arm mechanism 35.

[0141] In the embodiment, the linkage arm 4 is horizontally provided with a translation sliding groove 43, as shown in Figure 10 、 Figure 11 The length of the translation sliding groove 43 is adapted to the displacement stroke length of the shaft tube 11, the guide pin 31 is movably connected in the translation sliding groove 43, and the guide pin 31 can displace along the slot hole direction of the translation sliding groove 43;

[0142] The guide pin 31 will translate with the expansion and contraction of the shaft tube 11, and therefore it cannot be fixedly connected to the linkage arm 4. The translation sliding groove 43 with a length adapted to the displacement stroke length of the shaft tube 11 is provided on the linkage arm 4, and the guide pin 31 can translate with the shaft tube 11 while being connected to the linkage arm 4, which ensures that the expansion and contraction of the shaft tube 11 are not restricted by the guide pin 31 and the linkage arm 4.

[0143] In the embodiment, the button assembly 5 is provided with a second reset spring 54;

[0144] Further, one side of the button assembly 5 is provided with a mounting groove for accommodating the second reset spring 54, the bottom of the mounting groove is a boss, the second reset spring 54 is placed in the mounting groove, and the bottom end of the second reset spring 54 abuts against the boss, as shown in Figure 11 、 Figure 15 As can be seen, each linkage arm 4 on the side is also capable of connecting with the guide pin 31 provided on the first shaft tube 111 and the second shaft tube 112 simultaneously;

[0145] The other end of the second reset spring 54 can abut against the surface of the shaft tube 11 and realize compression of the second reset spring 54 with upward displacement of the button assembly 5, when the user controls the upward displacement of the button assembly 5 in the two end pivot structures 6 at the same time by operating the window 52, the second reset spring 54 abuts against the shaft tube 11 with displacement of the button assembly 5 and is compressed and deformed, when the pushing force driving the upward displacement of the button assembly 5 is removed, the second reset spring 54 can realize automatic reset of the button assembly 5 through rebound;

[0146] In the linkage system of the button assembly 5 and the self-locking block 2, when the first swing arm 36 and the second swing arm 37 move to the collinear dead point position, it corresponds to that the self-locking block 2 completely extends out of the surface of the shaft tube 11 and realizes axial locking with the disc 8, and also corresponds to that the unlocking slide handle 3 is not pulled backward by the guide pin 31; when the button assembly 5 is displaced upward, the guide pin 31 is moved obliquely upward by the linkage arm 4, which corresponds to that the unlocking slide handle 3 is pulled backward by the guide pin 31, the unlocking slide handle 3 is pulled backward, which actively breaks the collinear dead point position of the first swing arm 36 and the second swing arm 37, and also corresponds to that the axial locking of the self-locking block 2 with the disc 8 is released;

[0147] Since the unlocking slide handle 3 is pulled backward in the state, the first reset spring 34 accumulates potential energy for rebound, so when the button assembly 5 is released and the unlocking slide handle 3 is reset and rebounded by the first reset spring 34, the linkage button assembly 5 will naturally return downward, so in this embodiment, the second reset spring 54 plays a role in further controlling the reset of the button assembly 5.

[0148] In order to achieve the effect that the handle 7 is locked synchronously relative to the end pivot structure 6 when the self-locking block 2 is locked with the disc 8, the handle 7 is fixedly connected at both ends with a locking disc 72, as shown in Figure 15 ;

[0149] The locking disc 72 is coaxially rotatably connected with the handle 7, and the locking disc 72 is arranged in the cavity space of the end pivot structure 6 through the end pivot front cover 66;

[0150] The locking disc 72 is circumferentially provided with six symmetrically arranged locking grooves 73, as shown in Figure 15 ;

[0151] The center line direction of the locking disc 72 corresponds to the button assembly 5, as shown in Figure 15 ;

[0152] One side of the button assembly 5 is formed with a locking pin 74, as shown in Figure 12 ;

[0153] The locking pin 74 corresponds to the locking groove 73 in the vertical direction; further, only when the button assembly 5 is in the reset state, the locking pin 74 is inserted into the locking groove 73 and limited in the circumferential direction;

[0154] The reset state of the button assembly 5 is that the button assembly 5 is not displaced upward; in application, when the button assembly 5 is displaced upward, the axial locking between the self-locking block 2 and the disc 8 is released, and at this time Figure 12 The gap below the locking pin 74 shown in the figure corresponds to the locking groove 73, that is, the locking pin 74 is separated from the locking groove 73, and the button assembly 5 is released from the limiting of the locking disc 72, so that the disc 8 and the handle 7 are simultaneously released from the locking; when the button assembly 5 is released, the button assembly 5 returns to the reset state under the action of the linkage system of the button assembly 5 and the self-locking block 2 and the second reset spring 54, at this time the locking pin 74 is inserted into the locking groove 73 and limited in the circumferential direction, and the locking disc 72 cannot rotate in the circumferential direction, because the locking disc 72 is coaxially connected with the handle 7, and then the effect of locking the disc 8 in the axial direction and locking the handle 7 relative to the end pivot structure 6 is realized.

[0155] An observation window 62 is formed on the top surface of the end pivot structure 6, as shown in Figure 13 、 Figure 15 ;

[0156] An arc-shaped groove 65 is formed on the inner wall of the end pivot front cover 66, as shown in Figure 14 ; The arc-shaped groove 65 provides a swing track;

[0157] A swing block 63 swingable along the swing track of the arc-shaped groove 65 is movably arranged in the arc-shaped groove 65; one end of the swing block 63 is movably connected to the button assembly 5, as shown in Figure 12 ;

[0158] Specifically, a driving guide column 64 is formed on one side of the button assembly 5, as shown in Figure 15 ;

[0159] The swing block 63 is hinged to the end of the button assembly 5 through the cylindrical driving guide column 64 and swingably arranged in the arc-shaped groove 65; with the up-down reciprocating motion of the button assembly 5, the swing block 63 can swing in the circumferential direction in the arc-shaped groove 65 along the track of the arc-shaped groove 65;

[0160] Further, the size of the observation window 62 is adapted to each swing stable position of the swing block 63;

[0161] Specifically, each swing stable position of the swing block 63 is provided with a mark, respectively "lock" and "unlock", when the button assembly 5 is upwardly displaced, the swing block 63 swings along the arc-shaped slot 65 to the stable position of the "unlock" mark under the pushing of the button assembly 5, the "unlock" mark can be seen from the observation window 62; when the button assembly 5 returns to the reset state, the swing block 63 swings to another stable position in the opposite direction under the downward displacement of the button assembly 5, the "lock" mark is exposed to the observation window 62; thus the user can clearly know whether the dumbbell is currently in the locked state or not through the observation window 62.

[0162] In the embodiment, the dumbbell is provided with a placing base 9, as shown in Figure 17 ;

[0163] The placing base 9 is provided with a plurality of disc grooves 92 which can be used to prevent the disc 8, as shown in Figure 17 , Figure 19 ;

[0164] The placing base 9 is provided with a top rod 91 corresponding to the position of the operation window 52, the length of the top rod 91 corresponds to the stroke of the upward displacement of the button assembly 5, as shown in Figure 17 ;

[0165] Thus when the dumbbell is placed on the placing base 9, the top rod 91 is inserted into the operation window 52, the button assembly 5 is upwardly displaced under the pushing of the top rod 91, the self-locking block 2 is retracted into the shaft tube 11, the axial locking of the self-locking block 2 and the disc 8 is released, at this time the handle 7 restores the rotatable, the shaft tube 11 can be adjusted to be telescopic; when the dumbbell is taken up from the placing base, the top rod 91 is out of the operation window 52, it no longer applies the continuous pushing force to the button assembly 5, the button assembly 5 is reset to make the self-locking block 2 locked with the disc 8, at the same time the handle 7 is locked and can no longer be rotated.

[0166] Embodiment 2

[0167] The embodiment is different from the embodiment 1 in that in the embodiment, the shaft tube 11 is directly telescopically sleeved in the shaft tube 11 without the shaft inner tube 131, the linkage swing arm 22 of the extension section of the self-locking block 2 is directly hinged with the inner wall of the shaft tube 1; thus the self-locking block 2 is hinged with the inner wall of the shaft tube 11, which can also achieve the purpose of limiting the stroke range of the self-locking block 2.

[0168] In the embodiment, the through assembly hole 81 which is centrally provided in the disc 8 is a hexagonal hole;

[0169] The shape of the shaft tube 11 corresponds to the hexagonal hole, and the radial opposite self-locking block 2 and the locking swing arm mechanism 35 in the button assembly 5 system are still used, which can be correspondingly arranged on any two symmetrical shaft tube 11 surfaces of the hexagonal section of the shaft tube 11.

[0170] In the embodiment, the linkage arm mounting seat 53 is provided with a loose clamping structure, and the linkage arm mounting seat 53 is clamped and fixed with the linkage arm 4 through the clamping structure.

[0171] In the embodiment, the locking disc 72 is provided with eight symmetrical locking grooves 73.

[0172] Embodiment 3

[0173] The embodiment differs from the embodiment 1 in that, in the embodiment, the shaft inner tube 131 in the shaft tube 11 is sleeved on the shaft tube 11, and the two are gap-fitted and fixed through a positioning pin; in this way, the shaft inner tube 131 can be conveniently disassembled and replaced during later maintenance.

[0174] In the embodiment, the locking swing arm mechanism 35 includes two groups of symmetrical swing arms, and the two groups of swing arms are respectively connected with two groups of symmetrical self-locking blocks 2 and movably embedded on the surface of the shaft tube 11.

[0175] In the embodiment, the assembly hole 81 in the center of the disc 8 is a five-edged hole; the five-edged hole corresponds with the shaft tube 11 to realize the circumferential limiting of the disc 8, and the five-edged hole does not affect the mutual symmetry of the two groups of self-locking blocks 2 on the shaft tube 11; and the inner recess 82 formed in the assembly hole 81 corresponds with the self-locking block 2.

[0176] In the embodiment, the linkage arm mounting seat 53 is provided with a spring pin structure, and the linkage arm mounting seat 53 is pin-fixed with the linkage arm 4 through the spring pin structure.

[0177] The above are only specific embodiments of the present application, but the technical features of the present application are not limited to this. Any simple change, equivalent replacement or modification made on the basis of the present application to realize basically the same technical effect is covered in the protection scope of the present application.

Claims

1. A central tube group for heavy training equipment, comprising two shaft tubes (11) arranged in a same axis, and the two shaft tubes (11) can be axially displaced relative to each other, characterized in that: the shaft tube (11) is provided with at least one set of radially opposite self-locking blocks (2), the self-locking blocks (2) are movably embedded on the surface of the shaft tube (11), and the self-locking blocks (2) can be radially extended and retracted relative to the surface of the shaft tube (11); the shaft tube (11) is provided with an unlocking handle (3), and the unlocking handle (3) can slide along the axis of the shaft tube (11); each set of self-locking blocks (2) is linked with a set of locking swing arm mechanisms (35), the locking swing arm mechanisms (35) comprise two radially opposite swing arms, and the unlocking handle (3) drives the self-locking blocks (2) through the locking swing arm mechanisms (35); one end of the swing arm is movably connected to the self-locking block (2), and the other end is movably connected to the unlocking handle (3), and the axial sliding of the unlocking handle (3) can drive the two swing arms to swing between a co-linear dead point position and a parallel position; when the two swing arms are in the co-linear dead point position, the axes of the two swing arms are co-linear with the radial extension and retraction direction of the self-locking block (2), and the self-locking block (2) extends out of the surface of the shaft tube (11), and the self-locking block (2) in this state cannot be retracted by being pressed from the outside. the unlocking handle (3) is provided with a vertical guide groove (32), a guide pin (31) is movably embedded in the vertical guide groove (32) in a horizontal direction, and the guide pin (31) can move along the groove hole direction of the vertical guide groove (32); the unlocking handle (3) is externally provided with a separate inclined guide groove (33) independent of the unlocking handle (3), the inclined guide groove (33) is formed on the surface of the shaft tube (11), the guide pin (31) is connected to the inclined guide groove (33), and the guide pin (31) can slide along the groove hole direction of the inclined guide groove (33). One end of the unlocking handle (3) is provided with a first return spring (34), and the first return spring (34) is used for elastically returning the unlocked handle (3) after sliding. The self-locking block (2) is provided with a button assembly (5), the button assembly (5) is provided with a linkage arm (4), the linkage arm (4) is connected between the button assembly (5) and the guide pin (31), and the linkage arm (4) is used for transmitting the driving force of the button assembly (5) to the guide pin (31). The linkage arm (4) is provided with a horizontal translation sliding groove (43), the length of the translation sliding groove (43) is adapted to the displacement stroke length of the shaft tube (11), and the guide pin (31) is embedded in the translation sliding groove (43) and can slide along the groove hole direction of the translation sliding groove (43).

2. The center tube stack for a weight training machine of claim 1 wherein: Both ends of the handle (7) are connected with end pivot structures (6), and the handle (7) rotates relative to the end pivot structures (6) at both ends; the two shaft tubes (11) are respectively provided with sliding keys (13), and the inclination angles of the two sliding keys (13) are mirror-symmetrically arranged; the handle (7) is formed with a double-threaded screw (75) in a staggered manner, and the screw (75) is engaged with the two sliding keys (13) respectively.

3. The center tube stack for a weight training machine of claim 2 wherein: ​ 4. The center tube stack for a weight training machine of claim 2 wherein: ​ 5. The center tube stack for a weight training machine of claim 4 wherein: ​ 6. A dumbbell using the central tube set according to any one of claims 1 to 5, comprising a grip (7) fitted outside the central tube set (1), characterized in that: ​ 7. The dumbbell of claim 6, wherein: The self-locking block (2) is provided with a button assembly (5), the button assembly (5) is placed in the end pivot structure (6), the shell of the end pivot structure (6) is provided with an operation window (52), the button assembly (5) corresponds to the operation window (52) and interacts with the outside through the operation window (52).

8. The dumbbell of claim 6, wherein: The self-locking block (2) is provided with a button assembly (5), the button assembly (5) is placed in the end pivot structure (6), the end pivot structure (6) is provided with a locking disc (72) coaxially rotating with the handle (7), at least one locking groove (73) is arranged in the circumferential direction of the locking disc (72), the button assembly (5) is fixedly connected with a locking pin (74), the locking pin (74) can be matched and clamped into the locking groove (73) in the reciprocating stroke of the button assembly (5), and the locking pin (74) clamped into the locking groove (73) can limit the rotation of the locking disc (72).

9. The dumbbell of claim 6, wherein: The self-locking block (2) is provided with a button assembly (5), the button assembly (5) is placed in the end pivot structure (6), the shell of the end pivot structure (6) is provided with an observation window (62), the end pivot structure (6) corresponding to the observation window (62) is provided with an arc-shaped groove (65) inside, the arc-shaped groove (65) is provided with a swing block (63) swingable in the stroke range of the arc-shaped groove (65), one end of the swing block (63) is movably connected to the button assembly (5), and the button assembly (5) reciprocating will drive the swing block (63) to swing left and right in the arc-shaped groove (65), and the size of the observation window (62) is adapted to each swing stable position of the swing block (63).

10. The dumbbell of claim 6, wherein: The disc (8) movably connected to the central pipe group (1) is axially provided with an assembly hole (81) corresponding to the shaft pipe (11) for insertion, and the inner wall of the assembly hole (81) forms an inner groove (82), the position of the inner groove (82) corresponds to the position of the self-locking block (2) in the extended state, and the inner groove (82) can cooperate with the self-locking block (2) in the extended state to axially limit the disc (8).

11. The dumbbell of claim 10, wherein: The assembly hole (81) is a polygonal hole.

12. The dumbbell of claim 6, wherein: The placing base (9) for placing the dumbbell is provided with a top rod (91), the self-locking block (2) is provided with a button assembly (5), and the button assembly (5) corresponds to the top rod (91).

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