Adjustable barbell structure and weight plate for it, as well as method for unlocking the weight plate.

Abstract

An adjustable barbell structure comprises an adjustable weight unit with weight plates, each having a first and a second connecting section on two sides, which are convex and concave connecting sections, respectively, by which the weight plates are connected to one another, and a handle assembly with at least one connecting element with a third connecting section, which is either convex or concave, for connecting to the first or second connecting section. The convex connecting section has an interior, a locking element located therein, and an actuating opening and a locking opening connected to the interior. The concave connecting section has a locking groove for engaging with the locking element.The locking piece can be switched between a locked position and a non-locking position by means of a control element that is inserted into the interior through the actuating opening, allowing the user to quickly and conveniently adjust the number of weight plates.

Description

BACKGROUND OF THE INVENTION 1. Technical Field

[0001] The present invention relates to dumbbells for fitness activities such as strength training and in particular to an adjustable dumbbell structure and a weight plate therefor, as well as a method for unlocking the weight plate, which allows the user to quickly and conveniently adjust the required number of weight plates to adapt the weight of the dumbbell to the fitness requirements of the user. 2. Description of the state of the art

[0002] Dumbbells are now commonly used training equipment. Conventional dumbbells are made from a single piece of metal and their weight cannot be adjusted. For training with varying resistance, a dumbbell set is required, which contains several dumbbells with different weights, such as the "intelligent strength training system" disclosed in Taiwanese patent application TW M581492. With some dumbbells, the user can adjust the total weight by adding or removing weight plates at both ends of the handle, as with the "easy storage dumbbell set" disclosed in Taiwanese patent application TW I576135.

[0003] With the type of dumbbell described above, where the user can add or remove weight plates to adjust the weight, the user's primary concern is the ease of adding and removing the weight plates. However, conventional dumbbells of this type are often still too cumbersome when it comes to weight adjustment. Some require the entire set of weight plates to be removed before the desired number of plates can be selected and attached, or they have overly complex mechanisms for adding and removing weight plates, which can sometimes lead to user errors in weight setting. The user may not realize that the dumbbell is too heavy or too light until they actually hold and use it.Furthermore, some barbells use a locking mechanism between the weight plates, requiring the user to operate a switch on each plate to either lock or unlock the connection when adjusting the weight. This means the user must operate the switch on each plate individually. If confusion arises during the adjustment process, the user must check the switches on each plate individually, which is excessively cumbersome. Additionally, the switches are overly complex and comprise numerous components, leading to increased maintenance and repair costs. SUMMARY OF THE INVENTION

[0004] The present invention was developed taking into account the aforementioned circumstances. A main objective of the present invention is to provide an adjustable barbell structure and a weight plate for it, as well as a method for unlocking the weight plate, which allows the user to quickly and conveniently adjust the number of weight plates of the barbell to adapt the weight of the barbell to the user's needs and to quickly readjust if the weight is unsuitable, thus saving adjustment time and preventing the barbell from having overly complex mechanisms, which would lead to high maintenance and repair costs.

[0005] To achieve the aforementioned objective, the present invention provides an adjustable dumbbell structure comprising at least one adjustable weight unit, a handle assembly, and at least one control element. The adjustable weight unit comprises several weight plates. The weight plates are stackable and detachably connected to one another. Each weight plate comprises a first connecting section and a second connecting section, each located on two sides of the weight plate. In any pair of adjacent weight plates, the first connecting section of one weight plate is detachably connected to the second connecting section of the other weight plate. The handle assembly comprises a handle and at least one connecting element attached to the handle. The connecting element comprises a third connecting section.The third connecting section is detachably connected to the first or second connecting section of one of the weight plates of the adjustable weight unit. The adjustable barbell structure comprises several concave connecting sections and several convex connecting sections. Each of the concave connecting sections includes at least one locking groove. Each of the convex connecting sections comprises an interior space, at least one locking element located within the interior space, and at least one operating port and at least one locking port communicating with the interior space. The locking element comprises a locking section. The locking element can be switched between a locked position and a non-locked position by being controlled by the control element inserted into the interior space through the operating port.The first connecting section of each of the weight plates is the aforementioned convex connecting section.

[0006] The second connecting section of each of the weight plates is the aforementioned concave connecting section. The third connecting section of the handle assembly is one of the aforementioned convex and concave connecting sections. When one of the convex connecting sections is connected to one of the concave connecting sections, the locking element of the convex connecting section is in the locked position, and the locking element protrudes from the locking opening and engages in the locking groove of the concave connecting section. When the locking element is moved to the non-locking position, the locking element is moved inward and disengaged from the locking groove.

[0007] To achieve the aforementioned objective, the present invention provides a weight plate of an adjustable dumbbell structure that can be unlocked by a control element. The weight plate comprises a concave connecting section and a convex connecting section, each located on two sides of the weight plate. The concave connecting section includes a locking groove. The convex connecting section comprises an interior space, a locking element arranged in the interior space, and an operating opening and a locking opening that are connected to the interior space. The locking element comprises a locking section. The locking element can be switched between a locked position and a non-locked position by actuating the control element, which is inserted into the interior space through the operating opening.When the locking element of the convex connecting section is in the locked position, its locking portion protrudes from the locking opening to engage with the locking groove of the concave connecting section of another weight plate. When the locking element of the convex connecting section is switched from the locked position to the non-locked position, its locking portion moves inward to disengage from the locking groove.

[0008] To achieve the aforementioned objective, the present invention provides a method for unlocking weight plates for an adjustable barbell structure. The method for unlocking weight plates comprises the following steps: Providing an adjustable barbell structure, wherein the adjustable barbell structure comprises multiple weight plates, the weight plates being detachably connected to one another in a stacked manner, each weight plate comprising a concave connecting section and a convex connecting section, the concave connecting section and the convex connecting section being located on two sides of the weight plate, the concave connecting section comprising a locking groove, the convex connecting section comprising an interior, a locking element arranged in the interior, an actuating opening, and a locking opening communicating with the interior, for each pair of adjacent weight plates, the convex connecting section of one of the weight plates being detachably connected to the concave connecting section of the other weight plate.so that a locking part of the locking piece of the convex connecting section protrudes from the locking opening and engages in the locking groove of the concave connecting section; Providing a control element and inserting the control element into the interior through the operating opening of one of the weight plates and connecting it directly or indirectly to the locking piece; and

[0009] Using the control element to move the locking piece, the locking part of the locking piece is moved towards the interior to be released from the locking groove.

[0010] Therefore, before using the adjustable barbell structure, the user can operate the control element on the operating opening of the convex connecting section of one of the weight plates, according to the desired number of weight plates. By operating the control element with a simple and quick movement to move the locking piece of the convex connecting section of the controlled weight plate to the unlocked position, the connection between the convex connecting section of the controlled weight plate and the concave connecting section of the adjacent weight plate can be released. At this point, the two weight plates can be separated, so that the barbell assembly is equipped with only the number of weight plates desired by the user.To reconnect the weight plates, the user simply needs to operate the control element again with the same quick and easy movement to move the locking piece of the convex connecting section of the weight plate to be connected to the unlocked position, allowing the convex connecting section to be coupled with the concave connecting section of the other weight plate. The weight plates can then be securely connected by switching the locking piece of the convex connecting section to the locked position. Therefore, the present invention allows the user to quickly and conveniently adjust the number of weight plates on the barbell to adapt the weight to the user's training needs. Even if the weight is unsuitable, it can be quickly readjusted, saving setup time.Furthermore, the structure of the present invention is not overly complex, thus avoiding high repair and maintenance costs. Another advantage of the present invention is that it is not limited to the existing number of weight plates. Users can increase or decrease the number of weight plates according to their own needs, allowing users of varying strength to use it.

[0011] The further scope of application of the present invention will become apparent from the detailed description below. It should be understood, however, that while the detailed description and specific examples represent preferred embodiments of the invention, they serve only for illustrative purposes, as various changes and modifications within the scope of the invention will be apparent to the person skilled in the art from this detailed description. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a composite perspective view of an adjustable dumbbell structure according to a first preferred embodiment of the present invention. Fig. Figure 2 is an exploded view of the adjustable dumbbell structure. Fig. Figure 3 is an exploded view showing a base and control element of the adjustable dumbbell structure. Fig. 4 and Fig. 5 are exploded perspective views of a positioning element of the base and the control element. Fig. Figure 6 is a sectional view of part of the base and control element along line 6-6 in Fig. 2. Fig. Figure 7 is a composite perspective view of a handle arrangement of the adjustable dumbbell structure. Fig. Figure 8 is a composite perspective view of a weight plate of the adjustable barbell structure of “”. Fig. Figure 9 is an exploded view of the weight plate. Fig. Figure 10 is another composite perspective view of the weight plate. Fig. Figure 11 is a sectional view of part of the handle assembly and weight plates of the adjustable barbell structure along line 11-11 in Fig. 2. Fig. Figure 12 is a sectional view of part of the adjustable barbell structure along line 12-12 in Fig. 1. Fig. Figure 13 is a top view of part of the adjustable dumbbell structure. Fig. Figure 14 is a perspective view of part of the adjustable dumbbell structure, showing that the control element is inserted into one of the weight plates. Fig. Figure 15 is a sectional view along line 15-15 in Fig. 14. Fig. 16 resembles Fig. 15, however, shows the state in which the control element has been inserted into the weight plate and a guide chamfer of a drive section of the control element pushes a column. Fig. 17 resembles Fig. Figure 16, however, shows the state in which the control element is further inserted into the weight plate and the column is elastically pressed by an elastic element to engage in an arc-shaped recess of the control element. Fig. Figure 18 is a composite perspective view of an adjustable dumbbell structure according to a second preferred embodiment of the present invention. Fig. Figure 19 is an exploded view of the adjustable dumbbell structure. Fig. Figure 20 is a composite perspective view of a weight plate of the adjustable barbell structure. Fig. Figure 21 is an exploded view of the weight plate. Fig. Figure 22 is an approximate top view of the weight plate, but does not show the second and third discs. Fig. 23 and Fig. Figure 24 shows sectional views of the adjustable barbell structure, illustrating the process of inserting a control element of the adjustable barbell structure into the weight plate. Fig. 25 and Fig. Figure 26 are composite perspective views of a weight plate and a control element of an adjustable dumbbell structure according to a third preferred embodiment of the present invention. Fig. Figure 27 is an exploded view of the weight plate and control element. Fig. 28 is a front view of Fig. 26, which shows that the control element is in a retracted position. Fig. 29 resembles Fig. 28, however, shows that the control element is in an extended position. Fig. 30 to Fig. Figure 32 are composite perspective views of a weight plate and a control element of an adjustable dumbbell structure according to a fourth preferred embodiment of the present invention. Fig. Figure 33 is an exploded view of the weight plate and control element. Fig. 34 is roughly a front view of Fig. 32, however, does not show a third plate and shows that the control element is in a first angular position. Fig. 35 resembles Fig. Figure 34, however, shows that the control element is in a second angular position. Fig. 36 and Fig. Figure 37 are composite perspective views of a weight plate of an adjustable dumbbell structure according to a fifth preferred embodiment of the present invention. Fig. Figure 38 is an exploded view of the weight plate and a control element. Fig. 39 is roughly a front view of Fig. Figure 37, however, additionally shows the control element, does not show a third plate and shows that a locking piece is in a non-locking position. Fig. 40 resembles Fig. Figure 39, however, shows that the locking piece is in a locking position. DETAILED DESCRIPTION OF THE INVENTION

[0012] It should first be noted that identical or similar reference numerals used in the following embodiments and the appendix drawings denote identical or similar elements or their structural features throughout the entire description for the purpose of a concise presentation of the present invention. It should be noted that, for the sake of clarity, the components and structures shown in the figures are not drawn to scale and are depicted in their actual size, and that the features mentioned in the individual embodiments can also be applied in the other embodiments if this is feasible in practice.When it is mentioned that one element is placed on top of another, this also means that the first-mentioned element is placed directly on top of the last-mentioned element, or that the first-mentioned element is placed indirectly on top of the last-mentioned element via one or more other elements between the first-mentioned and the last-mentioned element. When it is mentioned that one element is placed directly on top of another element, this means that no other element is placed between the first-mentioned and the last-mentioned element.

[0013] With reference to Fig. 1 and Fig. Figure 2 comprises an adjustable dumbbell structure 100 according to a first preferred embodiment of the present invention, comprising a base 10, two adjustable weight units 20, a handle assembly 30, and two control elements 40. In the figures of this embodiment, only one of the control elements 40 is shown, which is arranged on one side of the base 10. The other control element 40 is arranged on the other side of the base 10. Fig. 2 shows that the two adjustable weight units 20 and the handle arrangement 30 together form a dumbbell.

[0014] As in Fig. 2 to Fig. As shown in Figure 6, the base 10 comprises a frame 11 and two positioning elements 12, which are arranged on two sides of the inner wall of the frame 11. As shown in Fig. As shown in Figure 7, the handle assembly 30 comprises a handle 31 and two connecting elements 32, each of which is rigidly connected to two ends of the handle 31. As shown in Fig. 2 and Fig. As shown in Figures 8-10, each of the adjustable weight units 20 comprises several weight plates 21, which are detachably arranged one above the other. In this embodiment, each adjustable weight unit 20 comprises three weight plates, but the number of weight plates is not limited thereto. Each of the weight plates 21 comprises a first connecting section 211 and a second connecting section 212, each located on two sides of the weight plate. In any pair of adjacent weight plates 21, the first connecting section 211 of one of the weight plates is detachably connected to the second connecting section 212 of the other weight plate, so that the multiple weight plates 21 are stacked and connected to form the adjustable weight unit 20. Furthermore, each of the connecting elements 32 of the aforementioned handle arrangement 30 comprises a third connecting section 321.The two adjustable weight units 20 are each detachably connected to the third connecting sections 321 of the two connecting elements 32. Furthermore, each of the positioning elements 12 of the aforementioned base 10 comprises a fourth connecting section 123. In the Fig. In the state shown in Figure 1, the two adjustable weight units 20 are each detachably connected to the fourth connecting sections 123 of the two positioning elements 12.

[0015] Furthermore, the first connecting section 211 of each of the weight plates 21 is a convex connecting section 50, and the second connecting section 212 of each of the weight plates 21 is a concave connecting section 60. Since each of the third connecting sections 321 of the handle assembly 30 is connected in this embodiment to the first connecting section 211 of one of the weight plates 21, each of the third connecting sections 321 is identical to the second connecting section 212 of the weight plate 21. That is, each of the third connecting sections 321 is a concave connecting section 60. In addition, each of the fourth connecting sections 123 of the base 10 is connected in this embodiment to the second connecting section 212 of one of the weight plates 21, so that each of the fourth connecting sections 123 is identical to the first connecting section 211 of the weight plate 21.That is, each of the fourth connecting sections 123 is a convex connecting section 50. However, the present invention can be modified such that the third connecting section 321 of the handle assembly 30 is connected to the second connecting section 212 of the weight plate 21, and the fourth connecting section 123 of the base 10 is connected to the first connecting section 211 of the weight plate 21. In this case, the third connecting section 321 is a convex connecting section 50, and the fourth connecting section 123 is a concave connecting section 60.

[0016] The above description shows that the adjustable dumbbell structure 100 comprises several convex connecting sections 50 and several concave connecting sections 60. The connection between the weight plates 21, the connection between the weight plate 21 and the connecting element 32 of the handle assembly 30, and the connection between the weight plate 21 and the positioning element 12 of the base 10 are all realized by the connection of the convex connecting section 50 with the concave connecting section 60, which are described in more detail below.

[0017] As in Fig. 2 and Fig. As shown in Figure 3, the frame 11 of the base 10 comprises two frame plates 111. Each of the frame plates 111 comprises an extension section 111a and two connecting sections 111b, each extending perpendicularly from two ends of the extension section 111a. As shown in Fig. 4 and Fig. As shown in Figure 5, each of the positioning elements 12 comprises an outer piece 121 and a locking piece 122. The outer piece 121 is bolted to one side of the locking piece 122. The fourth connecting section 123 is bolted to the other side of the locking piece 122. The outer piece 121 comprises an inner surface 121a and an outer surface 121b opposite the inner surface 121a. The inner surface 121a is attached to the locking piece 122. The outer surface 121b has a connecting groove 121c. The two frame plates 111 are arranged symmetrically to each other on two opposite outer edges of each of the positioning elements 12. The two connecting sections 111b of each of the frame plates 111 are each bolted in the connecting grooves 121c of the outer pieces 121 of the two positioning elements 12.Thus, the frame 11, consisting of the two frame plates 111, comprises two opposing inner surfaces 112, and the two positioning elements 12 are each attached to the two inner surfaces 112. The fourth connecting sections 123 of the two positioning elements 12 are opposite each other so that they can each be detachably connected to the two adjustable weight units 20. In this way, the two positioning elements 12 and the frame 11 can be firmly connected to each other to form the base 10 for the barbell, which consists of the two adjustable weight units 20 and the handle assembly 30, which can be safely placed on the base 10 when not in use. Furthermore, the two adjustable weight units 20 are designed so that the user can remove a portion of the weight plates 21 to adjust the weight of the barbell. The removed weight plates 21 can be safely stored on the base 10.

[0018] As in Fig. As shown in Figure 5, between the outer piece 121 and the blocking piece 122 of each of the positioning elements 12 of the base 10, an intermediate storage space 124 and an access opening 125 connected to the intermediate storage space 124 are formed so that the control element 40 can be inserted into the intermediate storage space 124 through the access opening 125 for temporary storage. In other words, the intermediate storage space 124 is configured so that when the user does not need the control element 40, they can insert it into the intermediate storage space 124 ( ) to prevent the control element 40 from being lost. Furthermore, the outer piece 121 is formed with a buckle recess 121d, which is arranged according to the intermediate storage space 124 and the access opening 125, and an engagement rib 121f, which projects from each of the two side walls 121e of the buckle recess 121d.When the control element 40 is inserted into the intermediate storage space 124 through the access opening 125, a control section 41, located at the upper end of the control element 40, is exposed in the buckle recess 121d. Furthermore, the control section 41 of the control element 40 has several arcuate engagement recesses 411, the number and position of which correspond to those of the engagement ribs 121f. When the control element 40 is inserted into the intermediate storage space 124, the arcuate engagement recesses 411 engage with the engagement ribs 121f and are positioned to temporarily and more securely hold the control element 40 in the intermediate storage space 124, thus preventing it from falling out and being lost.

[0019] With reference to the Fig. 4 to 10 Each of the convex connecting sections 50 of the adjustable dumbbell structure 100, i.e., each of the fourth connecting sections 123 and the first connecting sections 211 in this embodiment, comprises a first plate 51, a second plate 52, and a third plate 53. The first plate 51, the second plate 52, and the third plate 53 are stacked to form an interior space 54. More precisely, the first plate 51 has a locking opening 512 formed on an outer edge 511 of the first plate 51, and a locking piece receiving groove 513 extending from the locking opening 512 in a first direction (i.e., the positive direction of the Y-axis, which is in Fig. 4 and Fig. (as shown in Figure 9) extends into the first plate 51, meaning that the locking element receiving groove 513 is connected to the locking opening 512. The second plate 52 has an actuating opening 522 formed on an outer edge 521 of the second plate 52, and a control element receiving groove 523 extending from the actuating opening 522 in a second direction (i.e., the negative direction of the Z-axis, which is shown in Figure 9). Fig. 4 and Fig. (as shown in Figure 9) extends into the second plate 52, meaning that the control element receiving groove 523 is connected to the actuating opening 522. The control element receiving groove 523 extends in the same direction as the intermediate storage space 124 of the base 10. The actuating opening 522 and the access opening 125 point in the same direction. The control element receiving groove 523 and the locking piece receiving groove 513 together form the interior 54. That is, the operating opening 522 and the locking opening 512 are connected to the interior 54. The third plate 53 has a slide rail 531 that extends transversely along the Y-axis, meaning that the slide rail 531 runs parallel to the receiving groove 513 for the locking piece. In this embodiment, each of the convex connecting sections 50 is formed at its upper end with the operating opening 522 and on its side surface with the locking opening 512.However, the positions of the operating opening 522 and the locking opening 512 are not limited to this in the present invention.

[0020] Each of the convex connecting sections 50 further comprises an elastic locking device 70, which is mounted in the interior 54. In other words, the adjustable dumbbell structure 100 comprises several elastic locking devices 70. The number of elastic locking devices 70 corresponds to the number of convex connecting sections 50. Each of the elastic locking devices 70 comprises an elastic element 71, a locking piece 72, and a column 73. The elastic element 71 comprises a first end 711 and a second end 712. The first end 711 is attached to the inner surface of the interior 54. The second end 712 is attached to one end of the locking piece 72. In this embodiment, the locking piece receiving groove 513 is provided with a recess-shaped position limiting part 514.The first end 711 of the elastic element 71 is received in the position limiting part 514 and is elastically pressed against the base surface of the position limiting part 514. The second end 712 is attached to the locking piece 72. The locking piece 72 is slidably arranged in the locking piece receiving groove 513. The column 73 is attached to one side of the locking piece 72 and projects into the control element receiving groove 523. The terminal end of the column 73 is slidably arranged in the slide rail 531 of the third plate 53. In this way, the part of the column 73 that is located in the control element receiving groove 523 is positioned according to the operating opening 522, as shown in [reference]. Fig. Figure 13 shows that the column 73 is partially located below the operating opening 522. Therefore, when the user inserts the control element 40 through the operating opening 522 into the control element receiving groove 523, as shown in Figure 13, the column 73 is partially located below the operating opening 522. Fig. As shown in Figure 14, the control element 40 is pressed onto the column 73 to actuate the elastic locking device 70, which is described in more detail below.

[0021] With reference to the Fig. 7 to 9 Each of the concave connecting sections 60 of the adjustable dumbbell structure 100, i.e., each of the third connecting sections 321 and the second connecting sections 212 in this embodiment, comprises a main plate 61, two front plates 62, and two rear plates 63. The two rear plates 63 are spaced apart from each other and attached to one side of the main plate 61. The two front plates 62 are then stacked on top of the two rear plates 63. A mounting groove 64 is formed between the main plate 61, the two front plates 62, and the two rear plates 63. At least one of the front plates 62 is provided with a locking groove 621 on a side facing the mounting groove 64. The convex connecting sections 50 are detachably connected to the mounting grooves 64 of the concave connecting sections 60. That is, as in Fig. As shown in Figure 11, the multiple weight plates 21 of each of the adjustable weight units 20 are stacked and connected to one another by the connection of the convex connecting section 50 to the concave connecting section 60, and the convex connecting section 50 of one of the weight plates 21 is connected to the concave connecting section 60 of the handle assembly 30. Furthermore, as shown in Fig. Figure 12 shows the concave connecting section 60 of a further weight plate 21 of each of the adjustable weight units 20 being connected to the convex connecting section 50 of the base 10. The convex connecting sections 50 are connected to the concave connecting sections 60 such that the locking piece 72 of each of the convex connecting sections 50 engages in the locking groove 621 of the associated concave connecting section 60, as explained in more detail below.

[0022] As in Fig. As shown in Figure 15, when one of the convex connecting sections 50 and one of the concave connecting sections 60 are joined together, the locking element 72 of the convex connecting section 50 is elastically pressed by the elastic element 71, which normally positions it in a locking position P1. When the locking element 72 is in the locking position P1, a locking part 721 of the locking element 72 protrudes from the locking opening 512. The locking element 72 of the convex connecting section 50 is located according to the locking groove 621 of the concave connecting section 60. Therefore, when the locking element 72 is in the locking position P1, its locking part 721 can engage in the locking groove 621 of the concave connecting section 60. At this point, the convex connecting section 50 and the concave connecting section 60 are firmly and reliably connected to each other.After the user has inserted the control element 40 into the actuating opening 522 of one of the convex connecting sections 50, the control element 40 is inserted into the control element receiving groove 523 to actuate the column 73, which is located in the interior 54, as shown in . Fig. 16, to press, causing the column 73 to move along the slide rail 531 and causing the locking piece 72 to move along the locking piece receiving groove 513 towards the elastic element 71 to a non-locking position P2, as shown in Fig. 17 shown. In this process, the locking piece 72 elastically compresses the elastic element 71, and the locking part 721 of the locking piece 72 is moved towards the interior 54 and released from the locking groove 621, so that the convex connecting section 50 and the concave connecting section 60 can be separated from each other.

[0023] The assembly and disassembly method described above for the convex connecting section 50 and the concave connecting section 60 is applied not only between the weight plates 21, but also between the adjustable weight unit 20 and the connecting element 32 of the handle assembly 30, and between the adjustable weight unit 20 and the positioning part 12 of the base 10. When the first connecting section 211 of the adjustable weight unit 20 is connected to the third connecting section 321 of the handle assembly 30, the locking element 72 of the first connecting section 211 is in the locking position P1 and is engaged with the locking groove 621 of the third connecting section 321.If the user wishes to disconnect the first connecting section 211 from the third connecting section 321, they simply need to insert the control element 40 through its operating opening 522 into the first connecting section 211 to move the locking piece 72 of the first connecting section 211 to the non-locking position P2, thus allowing the adjustable weight unit 20 and the handle assembly 30 to be separated. When the second connecting section 212 of the adjustable weight unit 20 is connected to the fourth connecting section 123 of the base 10, the locking piece 72 of the fourth connecting section 123 is in the locked position P1 and engages with the locking groove 621 of the second connecting section 212.If the user wishes to separate the second connection section 212 from the fourth connection section 123, he simply needs to insert the control element 40 through its operating opening 522 into the fourth connection section 123 to move the locking piece 72 of the fourth connection section 123 into the non-locking position P2, so that the adjustable weight unit 20 and the base 10 can be separated from each other.

[0024] To enable the control element 40 to move the locking piece 72 smoothly, the control element 40 has a special configuration in this embodiment. The control element 40 comprises a body section 42, a positioning section 43, and a drive section 44, which are connected downwards from the control section 41 in that order. The control section 41 is designed as a long sheet and is hollow in its center. The body section 42 is designed as an elongated strip. The positioning section 43 is located at the lower end of the body section 42 and is narrower than the body section 42. The drive section 44 is a conical plate. More precisely, the positioning section 43 is provided with an arcuate recess 431 at a position corresponding to the column 73 when the control element 40 is inserted into the interior 54 of the convex connecting section 50.After the drive section 44 of the control element 40 has pressed the column 73 for displacement and the elastic element 71 has been simultaneously compressed when the column 73 is positioned according to the arcuate recess 431, the compressed elastic element 71 elastically returns to its original position to elastically press the column 73 so that it engages in the arcuate recess 431, thus limiting the length by which the locking piece 72 projects from the locking opening 512. For example, in this embodiment, the locking piece 72 is limited so that it does not project from the locking opening 512 at all, as shown in [reference]. Fig. 17 shown. This also allows the control element 40 to be held in a suitable position to prevent it from falling during use.

[0025] To enable the drive section 44 of the control element 40 to move the column 73 smoothly, the drive section 44 of the control element 40 is formed with two guide chamfers 442 between its terminal end 441 and the arcuate recess 431. In this embodiment, the drive section 44 of the control element 40 can be provided with the guide chamfer 442 only on one side, corresponding to the column 73, without the need for the guide chamfers 442 to be present on both sides. Each of the columns 73 is cylindrical. After the drive section 44 of the control element 40 has been inserted through the actuating opening 522 into the convex connecting section 50, the guide chamfer 442 of the drive section 44 gradually pushes the column 73 to move, as shown in Fig. 16 shown. In this way, the column 73 can be moved more reliably in order to move the locking piece 72 more reliably into the non-locking position P2.

[0026] As described above, during operation the user simply needs to pull out and insert the control element 40 to adjust the number of weight plates in each adjustable weight unit 20 and thus set the weight of each adjustable weight unit 20. First, pull out the control element 40 that was previously inserted into the base 10. Then, according to the desired number of weight plates, insert the control element 40 into the operating opening 522 of the convex connecting section 50 of one of the weight plates 21. For example, if the user wants the adjustable weight unit 20, which is combined with each connecting element 32 of the handle assembly 30, to have only two weight plates 21, they insert the control element 40 as shown in the diagram. Fig. Figure 14 shows that the control element 40 is inserted into the actuating opening 522 and moved continuously to push the column 73. The column 73 is pushed by the control element 40 to move laterally. The moving column 73 drives the locking piece 72 to move along with it. The moving locking piece 72 pushes the elastic element 71 and compresses it elastically. Simultaneously, the locking part 721 of the locking piece 72 gradually leaves the locking groove 621. After the locking piece 72 has been completely moved out of the locking groove 621, the user can hold the handle 31 to lift it, along with the adjustable weight units 20 connected to the connecting elements 32, and remove it from the base 10, allowing the user to perform a fitness exercise.For the user, adjusting the weight of the adjustable weight unit 20 is quick and easy, requiring only the effort of pulling out and inserting the control element 40. Furthermore, determining the currently selected weight is simpler based on the position of the control element 40. In contrast, conventional technology requires adjusting the switching structures of the weight plates individually, which is time-consuming, prone to errors, and too labor-intensive and expensive to repair and maintain. The present invention saves not only time and effort for the user, but also time and money on repairs and maintenance.

[0027] With reference to Fig. 18 to Fig. 24 is an adjustable dumbbell structure 200 according to a second preferred embodiment of the present invention, a kettlebell. Although the adjustable dumbbell structures 100, 200 of the first and second preferred embodiments are different types of dumbbell structures, they use a similar type of weight plate combination. The main difference between the adjustable dumbbell structure 200 of this embodiment and the first preferred embodiment is that the adjustable dumbbell structure 200 of this embodiment comprises only one adjustable weight unit 20, and the interior 54 of each weight plate 21A in this embodiment is equipped with two elastic locking devices 70. The structure of this embodiment is described in more detail below.

[0028] The adjustable barbell structure 200 comprises an adjustable weight unit 20, a handle assembly 30, a control element 40, and a base 80. The adjustable weight unit 20 comprises several weight plates 21A, which are stackable and detachably connected to one another. In this embodiment, the adjustable weight unit 20 comprises three weight plates 21A, but the number of weight plates 21A is not limited. Each of the weight plates 21A comprises a first connecting section 211 and a second connecting section 212, each located on opposite sides of the weight plate 21A. In any pair of adjacent weight plates 21A, the first connecting section 211 of one weight plate is detachably connected to the second connecting section 212 of the other weight plate, so that the multiple weight plates 21A are stacked and connected to form the adjustable weight unit 20.The handle assembly 30 comprises a handle 31 and a connecting element 32 attached to the handle 31. The handle 31 is curved, and both of its ends are attached to the connecting element 32. The connecting element 32 comprises a base plate 322 and a third connecting section 321. One side of the base plate 322 is integrally connected to the handle 31. The third connecting section 321 is bolted to another side of the base plate 322. The third connecting section 321 is detachably connected to the first connecting section 211 of one of the weight plates 21A of the adjustable weight unit 20. The base 80 comprises a bottom plate 81 and a fourth connecting section 82 located on one side of the bottom plate 81. The fourth connecting section 82 is detachably connected to the second connecting section 212 of one of the weight plates 21A of the adjustable weight unit 20.

[0029] Furthermore, the first connecting section 211 of each of the weight plates 21A is a convex connecting section 50, and the second connecting section 212 of each of the weight plates 21A is a concave connecting section 60. Since the third connecting section 321 of the handle assembly 30 is connected to the first connecting section 211 of one of the weight plates 21A in this embodiment, the third connecting section 321 is identical to the second connecting section 212 of the weight plate 21A. That is, the third connecting section 321 is a concave connecting section 60. Additionally, the fourth connecting section 82 of the base 80 is connected to the second connecting section 212 of one of the weight plates 21A in this embodiment, so that the fourth connecting section 82 is identical to the first connecting section 211 of the weight plate 21A. That is, the fourth connecting section 82 is a convex connecting section 50.However, the present invention can be modified such that the third connecting section 321 of the handle assembly 30 is connected to the second connecting section 212 of the weight plate 21A, and the fourth connecting section 82 of the base 80 is connected to the first connecting section 211 of the weight plate 21A. In this case, the third connecting section 321 is a convex connecting section 50, and the fourth connecting section 82 is a concave connecting section 60.

[0030] From the above description, it is evident that the adjustable barbell structure 200 comprises several convex connecting sections 50 and several concave connecting sections 60. The connection between the weight plates 21A, the connection between the weight plate 21A and the connecting element 32 of the handle assembly 30, and the connection between the weight plate 21A and the base 80 are all realized by connecting the convex connecting section 50 with the concave connecting section 60. The technical features and effects in this respect are similar to those of the first preferred embodiment, but exhibit some structural differences. The following description focuses primarily on these differences.

[0031] The base plate 81 of the base 80 comprises an upper plate 811 and a lower plate 812. The lower plate 812 is attached to one side of the upper plate 811. The fourth connecting section 82 is located on the other side of the upper plate 811. Between the upper plate 811 and the lower plate 812, two intermediate storage slots 813 and an access opening 814 are formed, which is connected to the two intermediate storage slots 813. The control element 40 comprises a control section 41 and two extension sections 45 extending from the control section 41. The base plate 81 of the base 80 is configured such that the two extension sections 45 of the control element 40 can be inserted through the access opening 814 into the two intermediate storage slots 813, so that the control element 40 is temporarily stored in the base plate 81 to prevent it from being lost.

[0032] Each of the convex connecting sections 50 of the adjustable dumbbell structure 200, i.e., each of the fourth connecting section 82 and the first connecting sections 211 in this embodiment, comprises a base plate 55 and a first plate 51, a second plate 52, and a third plate 53, which are stacked on the base plate 55 in that order and fastened with bolts. The first plate 51, the second plate 52, and the third plate 53 have a similar function to those in the first preferred embodiment, being stacked to form the interior 54. However, the first plate 51 in this embodiment has two oppositely oriented locking openings 512 and two locking-piece receiving grooves 513, each communicating with the two locking openings 512, and is installed therein with two elastic locking devices 70. Fig. Figure 20 shows only one of the locking openings 512, located on one side of the convex connecting section 50. The opposite side has the other locking opening 512. The locking pieces 72 of the two elastic locking devices 70 are each arranged in the two locking piece receiving grooves 513. The second plate 52 in this embodiment consists of three elongated plates 524, which are spaced apart, forming between them two actuation openings 522 and two control element receiving grooves 523, each of which is connected to the two actuation openings 522 so that the two extension sections 45 of the control element 40 can each be inserted through the two actuation openings 522 into the two control element receiving grooves 523 in order to press the columns 73 of the two elastic locking devices 70.Provided that each weight plate has two elastic locking devices 70, the weight plate may still be provided with only one actuating opening 522 and only one control element receiving groove 523, as long as the control element 40 inserted into the control element receiving groove 523 can simultaneously depress the columns 73 of the two elastic locking devices 70. The third plate 53 has two sliding slots 531. The columns 73 of the two elastic locking devices 70 are each arranged to slide within the two sliding slots 531. It should be noted that the convex connecting section 50 in the present invention is not limited to the sliding slot 531, as long as another mechanism for limiting the elastic locking device 70 is present in the interior 54. For example, the control element receiving groove 523 can be configured to limit the position of the column 73.However, the slide rail 531 can control the position of the column 73 and the locking piece 72 more precisely, thereby making the locking and non-locking relationship between the convex connecting section 50 and the concave connecting section 60 more reliable.

[0033] The elastic locking device 70 in this embodiment differs primarily from that in the first preferred embodiment in that each elastic locking device 70 comprises two elastic elements 71 ( ) and the inner surface of the interior 54 is correspondingly recessed with two position limiting parts 514 in the locking piece receiving groove 513. The locking piece 72 is likewise correspondingly recessed with two position limiting parts 722. The first end 711 and the second end 712 of each of the elastic elements 71 are received in the position limiting part 514 in the locking piece receiving groove 513 and the position limiting part 722 of the locking piece 72, respectively, and are elastically pressed onto their inner surfaces. In the present invention, however, the number of elastic elements 71 of the elastic locking assembly 70 is unlimited.Depending on the different design requirements, a different number of elastic elements 71 can be provided.

[0034] Each of the concave connecting sections 60 of the adjustable dumbbell structure 200, i.e., each of the third connecting sections 321 and the second connecting sections 212 in this embodiment, is similar to that in the first preferred embodiment, but the main difference between them is that the concave connecting section 60 in this embodiment comprises two opposing locking grooves 621. That is, the two locking grooves 621 point in opposite directions. The multiple weight plates 21A of the adjustable weight unit 20 are stacked and connected to one another by combining the convex connecting section 50 with the concave connecting section 60, and the convex connecting section 50 of one of the weight plates 21A is connected to the concave connecting section 60 of the handle assembly 30.Furthermore, the concave connecting section 60 of another weight plate 21A of the adjustable weight unit 20 is connected to the convex connecting section 50 of the base 80. The convex connecting sections 50 are connected to the concave connecting sections 60 such that the two locking pieces 72 of each of the convex connecting sections 50 engage with the two locking grooves 621 of the associated concave connecting section 60, as explained in more detail below.

[0035] As in Fig. 23 and Fig. As shown in Figure 24, the two locking pieces 72 in each of the convex connecting sections 50 can be simultaneously controlled by the control element 40, which is inserted into the interior 54 through the operating opening 522. This allows them to be switched between a locking position P1 and a non-locking position P2, and the two locking pieces 72 to be moved in opposite directions. That is, when the two locking pieces 72 are moved from their respective locking positions P1 to their respective non-locking positions P2, the two locking pieces 72 are moved towards each other; when the two locking pieces 72 are moved from their respective non-locking positions P2 to their respective locking positions P1, the two locking pieces 72 are moved away from each other.When the locking piece 72 is in the locking position P1, a locking part 721 of the locking piece 72 protrudes from the locking opening 512.

[0036] When one of the convex connecting sections 50 and one of the concave connecting sections 60 are joined together, the locking element 72 of the convex connecting section 50 is elastically pressed by the elastic element 71, which normally positions it in the locking position P1 and engages in the locking groove 621 of the concave connecting section 60. At this point, the convex connecting section 50 and the concave connecting section 60 are firmly and reliably engaged with each other.After the user has inserted the control element 40 into the actuating opening 522 of one of the convex connecting sections 50, the control element 40 pushes the columns 73 of the two elastic locking devices 70 located in the interior 54, thereby moving the locking pieces 72 of the two elastic locking devices 70 in opposite directions to their respective non-locking positions P2 and releasing them from the locking grooves 621, so that the convex connecting section 50 and the concave connecting section 60 can be separated from each other.The method of joining and separating the convex connecting section 50 and the concave connecting section 60 described above is applied not only between the weight plates 21A, , but also between the weight plate 21A of the adjustable weight unit 20 and the connecting element 32 of the handle assembly 30, as well as between the weight plate 21A of the adjustable weight unit 20 and the base 80.

[0037] The control element 40 in this embodiment also has the configuration to displace the locking piece 72 so that it moves more smoothly, similar to the first preferred embodiment. As in Fig. As shown in Figure 23, each extension section 45 of the control element 40 comprises a body section 42, a positioning section 43, and a drive section 44, connected in that order from the control section 41. The drive section 44 has a guide chamfer 442. The positioning section 43 has an arcuate recess 431. After the drive section 44 of the control element 40 is inserted into the actuating opening 522, the guide chamfer 442 of the drive section 44 gradually pushes the column 73 into displacement. In this way, the column 73 can be moved more reliably to move the locking piece 72 more reliably into the non-locking position P2.When the two columns 73 are positioned according to the arcuate recesses 431, the compressed elastic elements 71 elastically return to their original position, pressing the two columns 73 elastically into engagement with the arcuate recesses 431 and limiting the lengths by which the two locking pieces 72 protrude from the two locking openings 512. This also allows the control element 40 to be correctly positioned to prevent it from falling during use.

[0038] This allows the user to quickly remove or add weight plates 21A to the adjustable barbell structure 200 by simply pulling out and inserting the control element 40. This method saves time and effort and makes it easy to determine the currently selected weight based on the position of the control element 40. Furthermore, the structure of the present invention is not overly complex, thus saving time and money on repairs and maintenance.

[0039] Regardless of whether it is the type with two adjustable weight units 20 according to the first preferred embodiment or the type with only one adjustable weight unit 20 according to the second preferred embodiment, the locking mechanism between the convex connecting section 50 and the concave connecting section 60 is not limited to that provided in the aforementioned embodiments.It is only required that the convex connecting section 50 has an interior 54, a locking element 72 arranged in the interior 54, and an operating opening 522 and a locking opening 512 that communicate with the interior 54; that the concave connecting section 60 has a locking groove 621 that can engage with the locking element 72, which is located at the locking position P1; and that the convex connecting section 50 is configured such that a control element 40 can be inserted through the operating opening 522 into the interior 54 to switch the locking element 72 between the locking position P1 and the non-locking position P2. The following third to fifth preferred embodiments are examples that use different locking mechanisms to achieve similar effects to the first and second preferred embodiments.

[0040] It should be noted that in the first and second preferred embodiments described above, the control element 40 is inserted into the interior 54 through the operating opening 522 of the convex connecting section 50 only when it needs to be actuated. In the third to fifth preferred embodiments described below, however, the control element is located in the interior 54 without being removed. Therefore, each convex connecting section 50 is equipped with a control element. When the present invention refers to the control element being inserted into the interior through the operating opening, this includes both the case where the control element is inserted into the interior through the operating opening only when it needs to be actuated and the case where the control element remains permanently inserted into the interior.

[0041] With reference to the Fig. 25 to Fig. Figure 29 shows a weight plate 21B and a control element 40 according to the third preferred embodiment of the present invention to illustrate the locking mechanism between the convex connecting section 50 and the concave connecting section 60 of this embodiment. This locking mechanism is applicable between the weight plates 21B, between the weight plate 21B and a base 10 or base 80, as described above, and between the weight plate 21B and a handle assembly 30, as described above.

[0042] The weight plate 21B in this embodiment is similar to that in the first preferred embodiment, but has one essential difference: the control element 40 is arranged in the control element receiving groove 523 such that the control element 40 can be switched between a retracted position P3 and an extended position P4 by a linear movement by a user. Furthermore, the control element 40 comprises an inclined guide groove 46 and two positioning holes 47, 48. The first plate 51 of the convex connecting section 50 is accordingly provided with a positioning post 515. In addition, the locking piece 72 is only attached to the post 73, but not connected to an elastic element. The column 73 is inserted through the inclined guide groove 46 and the control element receiving groove 523 and into the slide rail 531 of the third plate 53.When the control element 40 is in the retraction position P3, the positioning column 515 is located in the positioning hole 47, the column 73 is located at an upper end 461 of the inclined guide groove 46, and the locking piece 72 is in the locking position P1. That is, at this point, the locking part 721 of the locking piece 72 protrudes from the locking opening 512 and can engage with the locking groove 621 of the concave connecting section 60.When the user pulls the control element 40 upwards, the positioning column 515 leaves the positioning hole 47, the control element 40 slides upwards along the control element receiving groove 523, and the column 73 is pressed by the inner wall of the inclined guide groove 46 to slide along the inclined guide groove 46, and the slider 531 slides along the slide rail 531 to move the locking piece 72, sliding along the locking piece receiving groove 513, thereby gradually moving the locking part 721 of the locking piece 72 towards the interior 54. When the control element 40 is in the extension position P4, the positioning column 515 is in the positioning hole 48, the column 73 is at a lower end 462 of the inclined guide groove 46, and the locking piece 72 is in the non-locking position P2.That is, at this point the locking part 721 of the locking piece 72 is retracted into the interior 54 without engaging with the locking groove 621 of the concave connecting section 60.

[0043] Consequently, in this embodiment, the locking mechanism between the convex connecting section 50 and the concave connecting section 60 allows the user to switch the locking element 72 between the locked position P1 and the unlocked position P2 simply by moving the control element 40 linearly, i.e., by pulling it up or pushing it down. Therefore, the user can quickly and conveniently adjust the number of weight plates on the barbell to adapt its weight to their needs. Furthermore, the structure of the present invention is not overly complex, thus saving time and money on repairs and maintenance.

[0044] With reference to Fig. 30 to Fig. Figure 35 shows a weight plate 21C and a control element 40 according to a fourth preferred embodiment of the present invention to illustrate the locking mechanism between the convex connecting section 50 and the concave connecting section 60 of this embodiment. This locking mechanism is applicable between the weight plates 21C, between the weight plate 21C and a base 10 or base 80, as described above, and between the weight plate 21C and a handle assembly 30, as described above.

[0045] The weight plate 21C in this embodiment is similar to that in the first preferred embodiment, but has one essential difference: the first plate 51 of the convex connecting part 50 has two locking openings 512 pointing in opposite directions and two locking piece receiving grooves 513, each of which is connected to the two locking openings 512. A locking piece 72 is mounted in each locking piece receiving groove 513. Each locking piece 72 is secured to a pillar 73. The front plate 62 of the concave connecting section 60 is correspondingly provided with locking grooves 621 that can engage with the two locking pieces 72. In addition, the first plate 51 is provided with a pivot axis 516. The control element 40 is correspondingly provided with a pivot hole 49.The pivot axis 516 is inserted into the pivot hole 49, so that the control element 40 is positioned in the control element receiving groove 523 such that the control element 40 can be switched between a first angular position P5 and a second angular position P6 by pivoting it. The control element 40 also includes two inclined guide grooves 46, each located on opposite sides of the pivot hole 49. The two columns 73 are each positioned in one of the two inclined guide grooves 46.

[0046] When the control element 40 is in the first angular position P5, the control section 41 of the control element 40 is deflected at its upper end to one side of the actuating opening 522, and the two locking pieces 72 are in their respective locking positions P1. That is, at this point, the locking parts 721 of the two locking pieces 72 protrude from the two locking openings 512 and can engage with the locking grooves 621 of the concave connecting section 60.When the user pushes the control section 41 of the control element 40 to the other side of the actuating opening 522, the two columns 73 are pushed through the inner walls of the two inclined guide grooves 46 to move in opposite directions and slide easily in the inclined guide grooves 46, causing the two locking pieces 72 to slide in opposite directions along the two locking piece receiving grooves 513, thereby gradually moving the locking parts 721 of the two locking pieces 72 towards the interior 54. When the control element 40 is in the second angular position P6, the two locking pieces 72 are in their respective non-locking positions P2. This means that at this point the locking parts 721 of the two locking pieces 72 are retracted into the interior 54 without engaging with the locking grooves 621 of the concave connecting section 60.

[0047] Consequently, in this embodiment, the locking mechanism between the convex connecting section 50 and the concave connecting section 60 allows the user to switch the two locking pieces 72 between the locked position P1 and the unlocked position P2 by simply pivoting the control element 40. Therefore, the user can quickly and conveniently adjust the number of weight plates on the barbell to adapt its weight to their needs. Furthermore, the structure of the present invention is not overly complex, thus saving time and money on repairs and maintenance.

[0048] With reference to the Fig.Figures 36 to 40 show a weight plate 21D and a control element 90 according to a fifth preferred embodiment of the present invention to illustrate the locking mechanism between the convex connecting section 50 and the concave connecting section 60 of this embodiment. This locking mechanism is applicable between the weight plates 21D, between the weight plate 21D and a base 10 or base 80, as described above, and between the weight plate 21D and a handle assembly 30, as described above.

[0049] The weight plate 21D in this embodiment is similar to that in the first preferred embodiment, but has one essential difference: the convex connecting section 50 comprises two first plates 51, each arranged on opposite sides of the second plate 52. The two first plates 51 are shaped oppositely in the left and right directions, such that the convex connecting section 50 has two locking openings 512 pointing in opposite directions and two locking-piece receiving grooves 513, each of which communicates with the two locking openings 512. A locking piece 72 is mounted in each locking-piece receiving groove 513. However, in this embodiment, there can only be one first plate 51 and only one locking piece 72.Furthermore, in each of the aforementioned embodiments, the control element 40 is configured to indirectly drive the locking piece 72 to move through the column 73, but in this embodiment, the control element 90 is configured to be rotated by the user to directly drive the locking piece 72 to move. The control element 90 is provided at its lower end with a gear section 91. Each of the locking pieces 72 is correspondingly provided with a rack section 723. The rack sections 723 of the two locking pieces 72 engage with the gear section 91 of the control element 90. The second plate 52 is provided with a control element receiving groove 523, the shape of which corresponds to the control element 90 and the locking pieces 72, so that the control element 90 can be rotatably arranged in the control element receiving groove 523.When the control element 90 is rotated, the gear section 91 drives the two locking pieces 72 to move in opposite directions between their respective locking positions P1 and non-locking positions P2. When the two locking pieces 72 are in their locking positions P1, the locking parts 721 of the two locking pieces 72 protrude from the two locking openings 512 and can engage with the locking grooves 621 of the concave connecting section 60. When the two locking pieces 72 are in their non-locking positions P2, the locking parts 721 of the two locking pieces 72 are retracted into the interior 54 without engaging with the locking grooves 621 of the concave connecting section 60.

[0050] Consequently, in this embodiment, the locking mechanism between the convex connecting section 50 and the concave connecting section 60 allows the user to switch the two locking pieces 72 between the locked position P1 and the unlocked position P2 by simply rotating the control element 90. Therefore, the user can quickly and conveniently adjust the number of weight plates on the barbell to adapt its weight to their needs. Furthermore, the structure of the present invention is not overly complex, thus saving time and money on repairs and maintenance.

[0051] In summary, the present invention provides a method for unlocking weight plates for an adjustable barbell structure, comprising the following steps.

[0052] Providing an adjustable barbell structure, for example, but not limited to, the type according to the first or second preferred embodiment. The adjustable barbell structure comprises several weight plates that are detachably arranged one above the other, for example, but not limited to, the weight plates 21, 21A-21D in the first to fifth preferred embodiments. Each of the weight plates comprises a concave connecting section 60 and a convex connecting section 50, each located on two sides of the weight plate. The concave connecting section 60 comprises a locking groove 621 or may comprise several locking grooves 621.The convex connecting section 50 comprises an interior 54, a locking element 72 (or several locking elements 72) arranged in the interior 54, and an operating opening 522 and a locking opening 512 (or several locking openings 512) that communicate with the interior 54. For each pair of adjacent weight plates, the convex connecting section 50 of one weight plate is detachably connected to the concave connecting section 60 of the other weight plate, such that a locking part 721 of the locking element 72 of the convex connecting section 50 projects from the locking opening 512 and engages in the locking groove 621 of the concave connecting section 60.

[0053] Providing a control element, such as, but not limited to, the control elements 40 and 90 in the first to fifth preferred embodiments, and inserting the control element into the interior 54 through the operating opening 522 of one of the weight plates and connecting it directly or indirectly to the locking element 72. For example, in the fifth preferred embodiment, the control element 90 is directly connected to the locking element 72, and in the first to fourth preferred embodiments, the control element 40 is indirectly connected to the locking element 72. The control element can be inserted into the interior 54 as needed or left permanently in the interior 54.

[0054] Use the control element to move the locking piece 72 so that the locking part 721 of the locking piece 72 is moved towards the interior 54 to be released from the locking groove 621.

[0055] The method for unlocking the weight plates for the adjustable barbell structure according to the present invention allows the user to quickly and conveniently adjust the number of weight plates in the barbell to adapt the weight to their needs. Even if the weight is unsuitable, it can be quickly readjusted, saving setup time. Furthermore, this prevents the barbell from having overly complex mechanisms, thus avoiding high maintenance and repair costs.

[0056] The description of the invention indicates that it can be varied in many ways. Such variations are not to be considered as deviations from the scope of the invention, and all modifications that are obvious to a person skilled in the art are to be included in the scope of the following claims. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] TW M581492

[0002] TW I576135

[0002]

Claims

[1] Adjustable barbell structure (100, 200), wherein the adjustable barbell structure (100, 200) characterized by is that it includes: at least one adjustable weight unit (20), wherein the adjustable weight unit (20) comprises several weight plates (21, 21A, 21B, 21C, 21D), wherein the weight plates (21, 21A, 21B, 21C, 21D) are detachably stacked, each of the weight plates (21, 21A, 21B, 21C, 21D) comprising a first connecting section (211) and a second connecting section (212), wherein the first connecting section (211) and the second connecting section (212) are each located on two sides of the weight plate (21, 21A, 21B, 21C, 21D), wherein for each pair of adjacent weight plates (21, 21A, 21B, 21C, 21D) the first connecting section (211) of one of the weight plates (21, 21A, 21B, 21C, 21D) is detachably connected to the second connecting section (212) of the other of the weight plates (21, 21A, 21B, 21C, 21D); a handle arrangement (30) with a handle (31) and at least one connecting element (32) attached to the handle (31), wherein the connecting element (32) has a third connecting section (321), the third connecting section (321) being detachably connected to the first connecting section (211) or the second connecting section (212) of one of the weight plates (21, 21A, 21B, 21C, 21D) of the adjustable weight unit (20); and at least one control element (40, 90); wherein the adjustable dumbbell structure (100, 200) comprises several concave connecting sections (60) and several convex connecting sections (50); each of the concave connecting sections (60) comprises at least one locking groove (621); each of the convex connecting sections (50) comprises an interior space (54), at least one locking element (72) arranged in the interior space (54), and at least one operating opening (522) and at least one locking opening (512) communicating with the interior space (54); the locking element (72) comprises a locking part (721); the locking element (72) can be switched between a locking position (P1) and a non-locking position (P2) by means of the control element (40, 90) which is inserted into the interior space (54) through the operating opening (522); the first connecting section (211) of each of the weight plates (21, 21A, 21B, 21C, 21D) is the convex connecting section (50);the second connecting section (212) of each of the weight plates (21, 21A, 21B, 21C, 21D) is the concave connecting section (60); the third connecting section (321) of the handle assembly (30) is either the convex connecting section (50) or the concave connecting section (60); when one of the convex connecting sections (50) is combined with one of the concave connecting sections (60), the locking piece (72) of the convex connecting section (50) is in the locking position (P1) and the locking part (721) of the locking piece (72) protrudes from the locking opening (512) and engages in the locking groove (621) of the concave connecting section (60); and when the locking piece (72) is moved into the non-locking position (P2), the locking part (721) is moved towards the interior (54) and released from the locking groove (621). [2] Adjustable dumbbell structure (100, 200) according to claim 1, characterized by, that the third connecting section (321) of the connecting element (32) of the handle assembly (30) is the concave connecting section (60) for the locking piece (72) of one of the first connecting sections (211) of the adjustable weight unit (20), which engages with the locking groove (621) of the third connecting section (321) when the locking piece (72) is in the locking position (P1). [3] Adjustable dumbbell structure (100) according to claim 1, characterized by , that the adjustable dumbbell structure (100) comprises two of the adjustable weight units (20); the handle assembly (30) comprises two such connecting elements (32); the two connecting elements (32) are each attached to two ends of the handle (31); the two adjustable weight units (20) are each detachably connected to the third connecting sections (321) of the two connecting elements (32). [4] Adjustable dumbbell structure (100) according to claim 3, characterized by , that the adjustable dumbbell structure (100) further comprises a base (10); the base (10) comprises a frame (11) and two positioning elements (12); the frame (11) comprises two opposing inner surfaces (112); the two positioning elements (12) are each attached to the two inner surfaces (112); each of the positioning elements (12) comprises a fourth connecting section (123); the fourth connecting sections (123) of the two positioning elements (12) are opposite each other and are each detachably connected to the two adjustable weight units (20); each of the fourth connecting sections (123) is either the convex connecting section (50) or the concave connecting section (60). [5] Adjustable dumbbell structure (100) according to claim 4, characterized by, that the fourth connecting section (123) of each of the positioning elements (12) of the base (10) is the convex connecting section (50) for the locking groove (621) of one of the second connecting sections (212) of each of the adjustable weight units (20) to engage with the locking piece (72) of the fourth connecting section (123) which is located at the locking position (P1); the third connecting section (321) of each of the connecting elements (32) of the handle assembly (30) is the concave connecting section (60) for the locking piece (72) of one of the first connecting sections (211) of each of the adjustable weight units (20) to engage with the locking groove (621) of the third connecting section (321) when the locking piece (72) is located at the locking position (P1). [6] Adjustable dumbbell structure (100) according to claim 4, characterized by, that each of the positioning elements (12) of the base (10) comprises an outer piece (121) and a blocking piece (122); the outer piece (121) is attached to one side of the blocking piece (122); the fourth connecting section (123) is attached to another side of the blocking piece (122); an intermediate storage space (124) and an access opening (125) connected to the intermediate storage space (124) are formed between the outer piece (121) and the blocking piece (122) so that the control element (40) can be inserted into the intermediate storage space (124) through the access opening (125) for intermediate storage. [7] Adjustable dumbbell structure (100) according to claim 6, characterized by, that the outer piece (121) has an inner side (121a) and an outer side (121b) facing away from the inner side (121a); ​​the inner side (121a) is attached to the blocking piece (122); the outer side (121b) is recessed with a connecting groove (121c); the frame (11) comprises two frame plates (111); each of the frame plates (111) comprises an extension section (111a) and two connecting sections (111b), each extending perpendicularly from two ends of the extension section (111a); and the two connecting sections (111b) of each of the frame plates (111) are each connected to the connecting grooves (121c) of the outer pieces (121) of the two positioning elements (12). [8] Adjustable dumbbell structure (100) according to claim 6, characterized by, that the outer part (121) is further formed with a buckle recess (121d) which is arranged according to the intermediate storage space (124) and the access opening (125), and has an engagement rib (121f) which projects from each of the two side walls (121e) of the buckle recess (121d); the control element (40) has several arcuate engagement recesses (411); when the control element (40) is inserted through the access opening (125) into the intermediate storage space (124), the control element (40) is partially exposed in the buckle recess (121d), and the arcuate engagement recesses (411) engage and are positioned in the engagement ribs (121f). [9] Adjustable dumbbell structure (200) according to claim 1, characterized by, that the adjustable dumbbell structure (200) comprises only a single adjustable weight unit (20); the handle assembly (30) comprises only a single connecting element (32); the handle (31) is curved and both ends of the handle (31) are attached to the connecting element (32). [10] Adjustable dumbbell structure (200) according to claim 9, characterized by , that the adjustable dumbbell structure (200) further comprises a base (80); the base (80) comprises a fourth connecting section (82); the fourth connecting section (82) of the base (80) is detachably connected to one of the first connecting sections (211) and the second connecting sections (212) of one of the weight plates (21A) of the adjustable weight unit (20); and the fourth connecting section (82) is either the convex connecting section (50) or the concave connecting section (60). [11] Adjustable dumbbell structure (200) according to claim 10, characterized by, that the fourth connecting section (82) of the base (80) is the convex connecting section (50) for the locking groove (621) of one of the second connecting sections (212) of the adjustable weight unit (20) to engage with the locking piece (72) of the fourth connecting section (82) which is located at the locking position (P1); the third connecting section (321) of the connecting element (32) of the handle assembly (30) is the concave connecting section (60) for the locking piece (72) of one of the first connecting sections (211) of the adjustable weight unit (20) which can engage with the locking groove (621) of the third connecting section (321) when the locking piece (72) is located at the locking position (P1). [12] Adjustable dumbbell structure (200) according to claim 10, characterized bythat the base (80) comprises a base plate (81); the base plate (81) comprises an upper plate (811) and a lower plate (812); the lower plate (812) is attached to one side of the upper plate (811); the fourth connecting section (82) is arranged on another side of the upper plate (811); at least one intermediate storage slot (813) and an access opening (814) connected to the intermediate storage slot (813) are formed between the upper plate (811) and the lower plate (812) so that the control element (40) can be inserted into the intermediate storage slot (813) through the access opening (814) for temporary storage. [13] Adjustable dumbbell structure (100, 200) according to claim 1, characterized by, that the adjustable dumbbell structure (100, 200) comprises several elastic locking devices (70); each of the convex connecting sections (50) is provided in its interior (54) with at least one of the elastic locking devices (70); each of the elastic locking devices (70) comprises an elastic element (71), a locking piece (72) and a column (73); the elastic element (71) comprises a first end (711) and a second end (712); the first end (711) is attached to an inner surface of the interior (54); the second end (712) is attached to one end of the locking piece (72); the locking section (721) of the locking piece (72) is located at another end of the locking piece (72); the locking piece (72) is elastically pressed by the elastic element (71) to be normally positioned at the locking position (P1);the column (73) is attached to one side of the locking piece (72) and arranged according to the operating opening (522); the control element (40) is detachably inserted into the interior (54) of any one of the convex connecting sections (50); after the control element (40) has been inserted into the operating opening (522) of any one of the convex connecting sections (50), the control element (40) pushes the column (73) in the interior (54), whereby the pushed column (73) moves the locking piece (72) into the non-locking position (P2) and elastically compresses the elastic element (71). [14] Adjustable dumbbell structure (100, 200) according to claim 13, characterized by, that each of the concave connecting sections (60) has two of the aforementioned locking grooves (621) in opposite directions; each of the convex connecting sections (50) has two of the aforementioned locking openings (512) in opposite directions and two locking piece receiving grooves (513) which are each connected to the two locking openings (512); each of the convex connecting sections (50) is provided in its interior (54) with two of the aforementioned elastic locking devices (70); the locking pieces (72) of the two elastic locking devices (70) are each arranged in the two locking piece receiving grooves (513);When the control element (40) is inserted into the operating opening (522) of one of the convex connecting sections (50), the control element (40) pushes the columns (73) of the two elastic locking devices (70) located in the interior (54) to move the locking pieces (72) of the two elastic locking devices (70) in opposite directions into their respective non-locking positions (P2). [15] Adjustable dumbbell structure (100, 200) according to claim 14, characterized by, that the control element (40) comprises a control section (41) and two control element extension sections (45) extending from the control section (41); each of the convex connecting sections (50) comprises two of the aforementioned actuating openings (522) and two control element receiving grooves (523), each of which is connected to the two actuating openings (522); when the control element (40) is inserted into one of the convex connecting sections (50), the two extension sections (45) are each inserted through the two actuating openings (522) into the two control element receiving grooves (523) in order to each press the columns (73) of the two elastic locking devices (70). [16] Adjustable dumbbell structure (100, 200) according to claim 13, characterized by, that each of the convex connecting sections (50) comprises a first plate (51), a second plate (52) and a third plate (53); the first plate (51), the second plate (52) and the third plate (53) are stacked to form the interior (54); the first plate (51) comprises a transversely recessed receiving recess (513) for a locking element and a position limiting element (514) arranged in the receiving recess (513) for a locking element; the second plate (52) has a vertically recessed receiving recess (523) for a control element; the third plate (53) comprises a transversely extending slide rail (531); the first ends (711) of the elastic elements (71) of the elastic locking devices (70) are attached to the position limiting parts (514) of the first plates (51) of the convex connecting sections (50);the columns (73) of the elastic locking devices (70) are slidably arranged in the sliding slots (531) of the third plates (53) of the convex connecting sections (50); after insertion into the operating opening (522) of any one of the convex connecting sections (50), the control element (40) is inserted into the control element receiving groove (523) of the second plate (52) to press the column (73), causing the column (73) to move along the sliding rail (531) of the third plate (53) and causing the locking piece (72) to move towards the elastic element (71) and compress the elastic element (71), while simultaneously releasing the locking piece (72) from the locking groove (621). [17] Adjustable dumbbell structure (100, 200) according to claim 13, characterized by, that the control element (40) comprises a control section (41), a body section (42), a positioning section (43) and a drive section (44) connected to each other in this order; the positioning section (43) is formed with an arc-shaped recess (431) at a position corresponding to the column (73) when the control element (40) is inserted into the interior (54) of the convex connecting section (50); After the control element (40) has moved the column (73) through the drive section (44) and the elastic element (71) is simultaneously compressed when the column (73) is located according to the arc-shaped recess (431), the compressed elastic element (71) elastically returns to its original position to elastically push the column (73) so that it engages in the arc-shaped recess (431), and limits a length by which the locking piece (72) protrudes from the locking opening (512). [18] Adjustable dumbbell structure (100, 200) according to claim 17, characterized by , that the drive section (44) of the control element (40) is formed with a guide chamfer (442) between its terminal end (441) and the arc-shaped recess (431); each of the columns (73) is cylindrical; after the drive section (44) of the control element (40) has been inserted into the actuating opening (522) of the convex connecting section (50), the guide chamfer (442) of the drive section (44) gradually displaces the column (73). [19] Adjustable dumbbell structure (100) according to claim 1, which characterized by The adjustable dumbbell structure (100) includes: a base (10) comprising a frame (11) and two positioning elements (12), wherein the frame (11) comprises two opposing inner surfaces (112), wherein the two positioning elements (12) are each arranged on the two inner surfaces (112), wherein each of the positioning elements (12) comprises a fourth connecting section (123), wherein the fourth connecting sections (123) of the two positioning elements (12) are opposite each other and form the convex connecting sections (50); wherein two of the adjustable weight units (20) are each detachably connected to the two positioning elements (12) of the base (10), wherein the second connecting section (212) of one of the weight plates (21) of each of the adjustable weight units (20) is detachably connected to the fourth connecting section (123) of the associated positioning element (12); wherein the handle arrangement (30) comprises the handle (31) and two connecting elements (32) each connected to two ends of the handle (31), wherein the two adjustable weight units (20) are each detachably connected to the two connecting elements (32), wherein the third connecting section (321) of each of the connecting elements (32) is the concave connecting section (60) and is detachably connected to the first connecting section (211) of one of the weight plates (21) of the associated adjustable weight unit (20); Several elastic locking devices (70), each arranged in the interiors (54) of the convex connecting sections (50), each of the elastic locking devices (70) comprising an elastic element (71), a locking piece (72) and a column (73), the elastic element (71) comprising a first end (711) and a second end (712), the first end (711) being elastically pressed against an inner surface of the interior (54), the second end (712) being attached to one end of the locking piece (72), the locking section (721) of the locking piece (72) being located at another end of the locking piece (72) and being elastically pressed by the elastic element (71) to normally protrude from the locking opening (512) and engage with the locking groove (621) of the concave connecting section (60),wherein the column (73) is attached to one side of the locking piece (72) and is arranged according to the operating opening (522); and, the control element (40) is detachably inserted into the interior (54) of any of the convex connecting sections (50) after the control element (40) has been inserted into the actuating opening (522) of any of the convex connecting sections (50), the control element (40) presses the column (73) which is located in the interior (54), whereby the pressed column (73) drives the locking piece (72) to elastically compress the elastic element (71), and at the same time releases the locking piece (72) from the locking groove (621). [20] Adjustable dumbbell structure (100, 200) according to claim 1, characterized by, that each of the concave connecting sections (60) comprises a main plate (61), two front plates (62) and two rear plates (63); the two rear plates (63) are attached to one side of the main plate (61); the two front plates (62) are each stacked on top of the two rear plates (63); a mounting groove (64) is formed between the main plate (61), the two front plates (62) and the two rear plates (63); at least one of the front plates (62) is formed on one side of it in the direction of the mounting groove (64) with the locking groove (621); and the convex connecting sections (50) are detachably connected to the mounting grooves (64). [21] Adjustable dumbbell structure (100, 200) according to claim 1, characterized by, that each of the convex connecting sections (50) comprises a receiving recess (513) for the locking piece and a receiving recess (523) for the control element; that the receiving recess (513) for the locking piece is connected to the locking opening (512); that the locking piece (72) is arranged in the locking piece receiving groove (513) and slides along the locking piece receiving groove (513) between the locking position (P1) and the non-locking position (P2); and that the receiving recess (523) for the control element is connected to the actuating opening (522) for the control element (40, 90), which is to be arranged in the receiving recess (523) for the control element. [22] Adjustable dumbbell structure (100, 200) according to claim 21, characterized by, that each of the convex connecting sections (50) comprises a first plate (51), a second plate (52) and a third plate (53); the first plate (51), the second plate (52) and the third plate (53) are stacked to form the interior (54); the locking opening (512) is formed on an outer edge (511) of the first plate (51); the locking element receiving groove (513) extends from the locking opening (512) in a first direction into the first plate (51); the actuating opening (522) is formed on an outer edge (521) of the second plate (52); the control element receiving groove (523) extends from the actuating opening (522) in a second direction into the second plate (52); and the first direction and the second direction are perpendicular to each other. [23] Adjustable dumbbell structure (100, 200) according to claim 21, characterized by , that the adjustable dumbbell structure (100, 200) includes several of the controls (40); Each of the convex connecting sections (50) is equipped with one of the control elements (40); the control element (40) is arranged in the control element receiving groove (523) such that the control element (40) can be switched between a retraction position (P3) and an extension position (P4) by being moved linearly in direction () by a user; the control element (40) includes an inclined guide groove (46); a column (73) is attached to the locking piece (72); the column (73) is arranged in the inclined guide groove (46); When the control element (40) is switched between the retraction position (P3) and the extension position (P4), the control element (40) pushes the column (73) so that it slides along the inclined guide groove (46) to drive the locking piece (72) so that it switches between the locking position (P1) and the non-locking position (P2). [24] Adjustable dumbbell structure (100, 200) according to claim 21, characterized by, that the adjustable dumbbell structure (100, 200) includes several of the control elements (40); each of the convex connecting sections (50) is equipped with one of the control elements (40); the control element (40) is arranged in the control element receiving groove (523) such that the control element (40) can be switched between a first angular position (P5) and a second angular position (P6) by pivoting it by a user; the control element (40) includes an inclined guide groove (46); a column (73) is attached to the locking piece (72); the column (73) is arranged in the inclined guide groove (46); and when the control element (40) is switched between the first angular position (P5) and the second angular position (P6), the control element (40) pushes the column (73) to move and drives the locking piece (72) to switch between the locking position (P1) and the non-locking position (P2). [25] Adjustable dumbbell structure (100, 200) according to claim 24, characterized by, that each of the convex connecting sections (50) comprises two of the said locking openings (512) in opposite directions, two of the said locking piece receiving grooves (513) which are each connected to the two locking openings (512), two locking pieces (72) which are each arranged in the two locking piece receiving grooves (513), and two columns (73) which are each attached to the two locking pieces (72); the control element (40) comprises two inclined guide grooves (46); the two columns (73) are each arranged in the two inclined guide grooves (46);and when the control element (40) is switched between the first angular position (P5) and the second angular position (P6), the control element (40) pushes the two columns (73) to move and drives the two locking pieces (72) to move in opposite directions in order to switch between the locked position (P1) and the non-locked position (P2). [26] Adjustable dumbbell structure (100, 200) according to claim 21, characterized by, that the adjustable dumbbell structure (100, 200) includes several of the control elements (90); each of the convex connecting sections (50) is equipped with one of the control elements (90); the control element (90) is rotatably arranged in the control element receiving groove (523) by a user; the control element (90) includes a gear section (91); the locking piece (72) includes a rack section (723); the rack section (723) engages with the gear section (91); and when the control element (40, 90) is rotated, the gear section (91) drives the locking piece (72) to move between the locked position (P1) and the unlocked position (P2). [27] Adjustable dumbbell structure (100, 200) according to claim 26, characterized by, that each of the convex connecting sections (50) has two of said locking openings (512) in opposite directions, comprises two locking piece receiving grooves (513) which each communicate with the two locking openings (512), and two locking pieces (72) which each are arranged in the two locking piece receiving grooves (513); the rack sections (723) of the two locking pieces (72) engage with the gear section (91) of the control element (90); and when the control element (90) is rotated, the gear section (91) drives the two locking pieces (72) to move in opposite directions between the locked position (P1) and the non-locked position (P2). [28] Weight plate (21, 21A, 21B, 21C, 21D) of an adjustable barbell structure (100, 200) which can be unlocked by a control element (40, 90), wherein the weight plate (21, 21A, 21B, 21C, 21D) characterized byis that this comprises a concave connecting section (60) and a convex connecting section (50), wherein the concave connecting section (60) and the convex connecting section (50) are each arranged on two sides of the weight plate (21, 21A, 21B, 21C, 21D), wherein the concave connecting section (60) comprises a locking groove (621), the convex connecting section (50) comprises an interior (54), a locking element (72) is arranged in the interior (54), and an actuating opening (522) and a locking opening (512) are provided which are connected to the interior (54), wherein the locking element (72) comprises a locking part (721), and wherein the locking element (72) can be switched between a locking position (P1) and a non-locking position (P2) by means of the control element (40, 90) is controlled, which is introduced into the interior (54) through the operating opening (522),when the locking element (72) of the convex connecting section (50) is in the locking position (P1), wherein the locking part (721) of the locking element (72) protrudes from the locking opening (512) to engage with the locking groove (621) of the concave connecting section (60) of another of the weight plates (21, 21A, 21B, 21C, 21D), when the locking element (72) of the convex connecting section (50) is switched from the locking position (P1) to the non-locking position (P2), wherein the locking part (721) of the locking element (72) is moved towards the interior (54) to be released from the locking groove (621). [29] Method for unlocking weight plates for an adjustable barbell structure (100, 200), wherein the method for unlocking weight plates characterized by The key is that it includes the following steps: Providing an adjustable barbell structure (100, 200), wherein the adjustable barbell structure (100, 200) comprises several weight plates (21, 21A, 21B, 21C, 21D), the weight plates (21, 21A, 21B, 21C, 21D) being removably arranged one above the other, each of the weight plates (21, 21A, 21B, 21C, 21D) comprising a concave connecting section (60) and a convex connecting section (50), the concave connecting section (60) and the convex connecting section (50) being arranged on two sides of the weight plate (21, 21A, 21B, 21C, 21D), the concave connecting section (60) comprising a locking groove (621), and the convex connecting section (50) comprising an interior (54), comprising a locking piece (72) arranged in the interior (54) and an actuating opening (522) and a locking opening (512) which are connected to the interior (54), wherein for each pair of adjacent weight plates (21, 21A, 21B, 21C,21D) has an actuating opening (522) and a locking opening (512) which are connected to the interior (54), wherein the convex connecting section (50) of one of the weight plates (21, 21A, 21B, 21C, 21D) is detachably connected to the concave connecting section (60) of the other of the weight plates (21, 21A, 21B, 21C, 21D) such that a locking part (721) of the locking piece (72) of the convex connecting section (50) projects out of the locking opening (512) and engages in the locking groove (621) of the concave connecting section (60); Providing a control element (40, 90) and inserting the control element (40, 90) into the interior (54) through the operating opening (522) of one of the weight plates (21, 21A, 21B, 21C, 21D) and connecting it directly or indirectly to the locking piece (72); and Using the control element (40, 90) to move the locking piece (72), thereby moving the locking section (721) of the locking piece (72) towards the interior (54) to be released from the locking groove (621).

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