CN220478018U - Chest expander - Google Patents

Abstract

The utility model discloses a chest expander, which comprises a flat shell with a containing cavity, a guide unit and a tension mechanism, wherein the guide unit and the tension mechanism are arranged in the containing cavity of the flat shell, the tension mechanism comprises a counterweight component and a pull-back device, the counterweight component comprises a magnetic resistance component and a driven turntable which are matched with each other, the magnetic resistance component applies resistance to the driven turntable, the pull-back device and the driven turntable are assembled in the containing cavity in parallel, the pull-back device and the driven turntable form transmission connection, a pull rope of the pull-back device is connected with the guide unit and extends out of the flat shell, so that the training of the body strength of a user is realized, meanwhile, the thickness of the chest expander is obviously reduced, the occupied space is obviously reduced, and the chest expander is convenient for the user to use or store and is suitable for being used in scenes such as families or offices.

Description

Chest expander

Technical Field

The utility model relates to the technical field of fitness equipment, in particular to a chest expander.

Background

Along with the continuous improvement of living standard, people pay more and more attention to physical health. Therefore, various fitness equipments are also spreading in our lives, and the chest expander is used as a fitness equipment for strength training, and is used for physical training in strength.

The existing chest expander adopts a driving component with a motor as a resistance source, the driving component with the motor outputs corresponding moment to a pull rope, a counter weight is simulated, and counter weight pulling force is generated on the pull rope, but the chest expander with the driving component with the motor has a complex structure, so that the chest expander has a large thickness, occupies more space and is inconvenient for users to use or store.

Disclosure of Invention

Therefore, the utility model aims to solve the problems and provide the chest expander, which can effectively reduce the thickness and is convenient for users to use or store.

In order to achieve the above purpose, the technical scheme provided by the utility model is as follows:

the utility model provides a chest expander, is in including having the flat casing that holds the cavity and setting is in direction unit and the pulling force mechanism in the holding the cavity of flat casing, the pulling force mechanism includes counter weight subassembly and pullback, the counter weight subassembly is including matched with magnetic resistance subassembly and driven carousel, the magnetic resistance subassembly is right the resistance is applyed to driven carousel, the pullback with driven carousel is assembled side by side in holding the cavity, the pullback with driven carousel forms the transmission and connects, the stay cord of pullback is connected direction unit and extends to outside the flat casing.

Further, the number of the tension mechanisms is two, and the two tension mechanisms are rotationally symmetrically arranged at the left side and the right side of the accommodating cavity; each tension mechanism is provided with a guide unit.

Further, still include adjustment mechanism, adjustment mechanism sets up hold the middle part of cavity, and be located between two pulling force mechanisms, adjustment mechanism includes driver and connecting unit, the driver is connected connecting unit, connecting unit connects the magnetic resistance subassembly.

Further, the connecting unit comprises a connecting sheet, a connecting rod and a pull rod, wherein the connecting sheet is rotatably assembled in the middle of the flat shell, the driver is fixedly assembled in the flat shell and is arranged in parallel with the connecting sheet in the front-back direction, one end of the connecting rod is connected with the driver, the other end of the connecting rod is hinged to the connecting sheet, one end of the pull rod is hinged to the connecting sheet, and the other end of the pull rod is hinged to the magnetic resistance assembly.

Further, the reluctance assembly includes a magnet and a bracket, the driven turntable having a soft magnetic property, the bracket being hinged to the flat housing; the support has the mounting lug that is located upper and lower both ends and outside protruding extension of mounting plate, two mounting lugs are the interval setting, and with the mounting plate is connected to form a holding tank, magnet fixed assembly is in on the mounting lug, driven carousel's part is inserted and is established in the holding tank.

Further, the pullback device comprises a rotary disc, a pull rope, a connecting shaft and a scroll spring, wherein the rotary disc is provided with a central through hole which is penetrated, the connecting shaft rotatably penetrates through the central through hole and is fixedly assembled in the flat shell, one end of the scroll spring is fixed on the connecting shaft, the other end of the scroll spring is fixed on the rotary disc, the pull rope is wound on the rotary disc, one end of the pull rope is fixed on the rotary disc, and the other end of the pull rope is connected with the guide unit and extends out of the flat shell.

Further, the pullback device and the driven turntable form a transmission connection through a conveyor belt.

Further, the conveyor belt conveyor further comprises a tensioner, wherein the tensioner is arranged corresponding to the conveyor belt so as to adjust the tightness of the conveyor belt.

Further, the guide unit includes support frame, spacing axle, first leading wheel and second leading wheel, support frame fixed assembly is in hold on the lateral wall of cavity, spacing axle rotatable assembly is in on the support frame, first leading wheel with the second leading wheel is all assembled on the support frame, just the axis of first leading wheel with the axis mutually perpendicular of second leading wheel, spacing axle corresponds first leading wheel, just spacing axle with the wheel face of first leading wheel is the interval setting, the support frame has the guide through-hole, the guide through-hole is located the second leading wheel with between the first leading wheel, the stay cord of pullback ware is around locating behind the part wheel face of second leading wheel, through the guide through-hole, again around locating the part wheel face of first leading wheel, later wear to establish first leading wheel with clearance between the spacing axle, after that extend to outside the flat shell.

Further, the flat shell comprises a mounting frame and a supporting frame with a hollowed middle, the guide unit is assembled on the supporting frame, the mounting frame comprises an upper mounting plate and a lower mounting plate, the upper mounting plate and the lower mounting plate are respectively and fixedly assembled in openings on the upper side and the lower side of the supporting frame, and the opening is jointly surrounded by the supporting frame to form the accommodating cavity.

The technical scheme provided by the utility model has the following beneficial effects:

the counterweight component and the pullback device are arranged in the flat shell in parallel, the driving component with a motor is replaced by the counterweight component and the pull mechanism matched with the pullback device, and the guide unit matched with the counterweight component is arranged in the flat shell, so that the thickness of the pullback device is obviously reduced while the force training of the pullback device to a user is realized, the occupied space is obviously reduced, the use or the storage of the pullback device by the user is facilitated, and the pullback device is suitable for being used in scenes such as families or offices.

Drawings

FIG. 1 is a schematic view of a portion of a chest expander in an embodiment;

FIG. 2 is a schematic diagram of a chest expander according to an embodiment;

FIG. 3 is a schematic view of a flat housing in an embodiment;

FIG. 4 is a schematic diagram of a magnetoresistive assembly according to an embodiment;

FIG. 5 is a schematic view of an adjustment mechanism according to an embodiment;

fig. 6 is an enlarged schematic view of the region a in fig. 2.

Detailed Description

For further illustration of the various embodiments, the utility model is provided with the accompanying drawings. The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate embodiments and together with the description, serve to explain the principles of the embodiments. With reference to these matters, one of ordinary skill in the art will understand other possible embodiments and advantages of the present utility model. The components in the figures are not drawn to scale and like reference numerals are generally used to designate like components.

The utility model will now be further described with reference to the drawings and detailed description.

Referring to fig. 1 to 6, as an exercise machine for strength training, a chest expander comprises a flat housing 1 having a housing cavity (not shown), a guide unit 5 and a tension mechanism 4 disposed in the housing cavity of the flat housing 1, the tension mechanism 4 comprising a weight assembly 3 and a retractor 2, the weight assembly 3 comprising a reluctance assembly 32 and a driven turntable 31 which are matched, the reluctance assembly 32 exerting resistance to the driven turntable 31, the retractor 2 and the driven turntable 31 being assembled in parallel in the housing cavity, the retractor 2 and the driven turntable 31 forming a transmission connection; the pull cord 21 of the retractor 2 is connected to the guide unit 5 and extends out of the flat housing 1.

The reluctance assembly 32 and the driven turntable 31 cooperate with each other to form a magnetic force for preventing the driven turntable 31 from rotating, and a user applies an upward pulling force to the pull cord 21 of the retractor 2 to overcome the resistance between the reluctance assembly 32 and the driven turntable 31 (i.e., the magnetic force formed between the reluctance assembly 32 and the driven turntable 31) to drive the rotating portion (i.e., the rotating disc) of the retractor 2 to rotate, thereby realizing a weight pulling force.

When the user applies a pulling force to the pulling rope 21 along the extending direction (i.e., upward direction) of the guiding unit 5, the reluctance component 32 applies a resistance to the driven turntable 31, and is connected with the driving of the pullback device 2 through the driven turntable 31, so that the pullback device 2 is limited by the resistance, the pulling force of the pulling rope 21 of the pullback device 2 pulled upwards by the user continuously overcomes the resistance limitation to drive the rotation part of the pullback device 2 to rotate, and the resistance at this time is a counterweight pulling force, and meanwhile, the rotation torque of the elastic part (i.e., the scroll spring) of the pullback device 2 is increased.

When the pull rope 21 of the pullback device 2 is retracted and the user does not actively apply the upward pulling force, the rotation torque of the elastic part of the pullback device 2 overcomes the resistance limitation of the counterweight assembly 3 on the rotation part of the pullback device 2, so that the rotation part of the pullback device 2 rotates, the pull rope 21 is wound back on the rotation part of the pullback device 2, and the repeated circulation is performed in this way, and further the training of the body strength by the user is realized, so that the body-building effect is achieved.

The counterweight assembly 3 and the pullback device 2 are arranged in the flat shell 1 in parallel, the driving assembly with a motor is replaced by the tension mechanism 4 matched with the counterweight assembly 3 and the pullback device 2, and the matched guide unit 5 is arranged in the flat shell 1, so that the thickness of the pullback device is obviously reduced while the force training of the pullback device on a user is realized, the occupied space is obviously reduced, the use or the storage of the pullback device is facilitated for the user, and the pullback device is suitable for being used in scenes such as families or offices.

In another preferred embodiment, the flat housing 1 includes a mounting frame 11 and a supporting frame 13 with a hollow middle, the guide unit 5 is assembled on the supporting frame 13, the mounting frame 11 includes an upper mounting plate 111 and a lower mounting plate 112, and the upper mounting plate 111 and the lower mounting plate 112 are respectively and fixedly assembled in openings on the upper and lower sides of the supporting frame 13, and are enclosed together with the supporting frame 13 to form the accommodating cavity.

In particular, the length of the flat housing 1 in the lateral direction and the width thereof in the front-rear direction are both larger than the height of the flat housing 1 in the up-down direction.

The end of the pull rope 21 outside the flat shell 1 is provided with a handle 211, so that a user can conveniently apply pulling force to the pull rope 21, and the pull rope is convenient for the user to perform pulling force training movement more comfortably.

The braced frame 13 is flat, and mounting bracket 11 sets up in flat braced frame 13, and pullback 2 and driven carousel 31 set up side by side and rotatable assembly in mounting bracket 11 in the width direction of flat casing 1, and guide unit 5 is located braced frame 13's side and corresponds the exit that stay cord 21 extended from the gyration of pullback 2 to form the appearance structure of the apparent less chest expander of thickness, and then reduce the whole occupation space of chest expander, convenience of customers uses or accomodates, is fit for using in scene such as family or office.

Of course, the structure of the flat housing 1 is not limited thereto, and for example, the flat housing 1 may further include an upper cover and a rear housing, wherein the upper cover is covered on the rear housing to completely wrap the accommodating cavity, the supporting frame 13 and the mounting frame 11 in the flat housing 1, so that the overall appearance of the chest expander is more attractive.

In another preferred embodiment, the number of the tension mechanisms 4 is two, the two tension mechanisms 4 are rotationally symmetrically arranged at the left side and the right side of the accommodating cavity, each tension mechanism 4 is provided with one guide unit 5, so that the structure is simple, the stress distribution of the structure is uniform, the two tension mechanisms 4 and the two guide units 5 are reasonably arranged at corresponding mounting positions in a manner of fully utilizing the space in the accommodating cavity of the flat shell 1, so as to realize the thickness reduction effect of the chest expander, and the chest expander formed by the two tension mechanisms 4 and the corresponding guide units 5 can synchronously perform collaborative training on the left and right moving parts (such as two hands) of the body of a user, so that the body of the user reciprocates in a manner of elastic action, the training action of the user is more coordinated, and the user is not easy to feel tired and monotone in the training.

Specifically, the chest expander still includes adjustment mechanism 6, adjustment mechanism 6 sets up hold the middle part of cavity, and be located between two pulling force mechanisms 4, adjustment mechanism 6 includes driver 61 and connecting unit (not shown), driver 61 connects the connecting unit, the connecting unit is connected the reluctance unit 32 is adjusted pulling force mechanism 4's resistance through adjustment mechanism 6 to satisfy different users ' training intensity's requirement, perhaps with the required training intensity of matching same user at different training periods, effectively utilize simultaneously hold the regional space in middle part in cavity.

Further preferably, the connection unit includes a connection piece 62, a connection rod 63, and a pull rod 64, where the connection piece 62 is rotatably assembled in the middle of the flat housing 1, the driver 61 is fixedly assembled in the flat housing 1 and is disposed in parallel with the connection piece 62, one end of the connection rod 63 is connected with the driver 61, the other end is hinged to the connection piece 62, one end of the pull rod 64 is hinged to the connection piece 62, and the other end is hinged to the reluctance component 32.

In this embodiment, the flat housing 1 further includes a fixing plate 12, the fixing plate 12 is fixedly assembled in the middle of the supporting frame 13, the number of the installation frames 11 is two, the two installation frames 11 are respectively arranged at the left side and the right side of the supporting frame 13 in a rotationally symmetrical manner, so as to correspond to the two tension mechanisms 4, and the cavity formed by connecting the supporting frame 13, the two installation frames 11 and the 1 fixing plate 12 is a containing cavity of the flat housing 1, and also, the connecting piece 62 is assembled in the middle of the fixing plate 12 in a pin shaft connection manner and forms a first hinge point, at this time, the connecting piece 62 is also located in the middle of the containing cavity, and the driver 61 is fixed at the front of the fixing plate 12 in a riveting manner and is arranged in parallel with the connecting piece 62 in the front-rear direction.

The two tension mechanisms 4 are a first tension mechanism (not shown) located at the left side and a second tension mechanism (not shown) located at the right side, the number of the connecting pieces 62 and the connecting rods 63 is 1, the number of the tie rods 64 is two, the two tie rods 64 are located at the front side and the rear side of the connecting piece 62 (i.e., the width direction of the flat housing 1), and the two tie rods 64 are a first tie rod (not shown) located at the front side of the connecting piece 62 and a second tie rod (not shown) located at the rear side of the connecting piece 62 in sequence.

The connecting piece 62 is provided with 1 protruding connecting convex block (not shown), one end of the connecting rod 63 is connected with the driver 61, the other end of the connecting rod 63 is hinged with the connecting convex block at the second hinging point 621, and the driver 61 drives the connecting rod 63 to move so as to drive the connecting piece 62 to rotate around the first hinging point as a center in a certain angle range on the fixed plate 12.

The first pull rod hinged connection piece 62 is at a third hinged point 622, the second pull rod hinged connection piece 62 is at a fourth hinged point 623, and the third hinged point 622 and the fourth hinged point 623 are circumferentially arranged on a concentric circular arc taking the first hinged point as the same circle center.

The first pull rod articulates the reluctance component 32 of the first tension mechanism, so that the reluctance component 32 of the first tension mechanism and the adjusting mechanism 6 form an articulated connection to realize the adjustment of the resistance.

The second pull rod is hinged with the magnetic resistance component 32 of the second tension mechanism, so that the magnetic resistance component 32 of the second tension mechanism is connected with the adjusting mechanism 6 to realize the adjustment of resistance.

In another preferred embodiment, the reluctance assembly 32 includes a magnet 322 and a bracket 321, the driven turntable 31 has soft magnetism, the bracket 321 is hinged to the flat housing 1, the bracket 321 has a bracket plate 3211 and mounting protrusions 3212 located at upper and lower ends of the bracket plate 3211 and extending outwards in a protruding manner, the two mounting protrusions 3212 are disposed at a distance, and are connected with the bracket plate 3211 to form a receiving groove 323, the magnet 321 is fixedly mounted on the mounting protrusions 3212, and a portion of the driven turntable 31 is inserted into the receiving groove 323.

When the driver 61 drives the connecting rod 63 to move upwards, the connecting rod 63 drives the connecting piece 62 to rotate around the first hinge point by a certain angle in a clockwise direction, and then synchronously drives the pull rod 64 to move in the first direction, so as to drive the bracket 321 to drive the magnet 322 to be away from the axis of the driven turntable 31, the area of the driven turntable 31 in the accommodating groove 323 is reduced, and the resistance of the magnetic resistance component 32 to the magnetic force of the driven turntable 31 is also reduced so as to reduce the counterweight pulling force of the chest expander and reduce the training strength of the chest expander.

When the driver 61 drives the connecting rod 63 to move downward, the connecting rod 63 drives the connecting piece 62 to rotate around the first hinge point by a certain angle in a counterclockwise direction, so as to drive the bracket 321 and the magnet 322 to approach the axis of the driven turntable 31, the area of the driven turntable 31 located in the accommodating groove 323 is increased, and the resistance of the magnetic resistance component 32 to the magnetic force of the driven turntable 31 is also increased, so that the counterweight pulling force of the chest expander is increased, and the training strength of the chest expander is enhanced.

In a specific implementation, the driven turntable 31 is made of soft magnetic metal (such as carbon steel, etc.), the magnets 322 are made of permanent magnets (such as permanent ferrite materials or neodymium iron boron permanent magnet materials, etc.), the number of the magnets 322 is 6, however, in other embodiments, the number of the magnets 322 is determined according to the resistance requirement of the chest expander, for example, the number of the magnets 322 is 4, 8 or 10, etc.

The number of the reluctance components 32 is two, namely a first reluctance component (not shown) and a second reluctance component (not shown), the first reluctance component is the reluctance component 32 of the first tension mechanism, the second reluctance component is the reluctance component 32 of the second tension mechanism, the first reluctance component comprises a first bracket (not shown) and a first magnet (not shown), the second reluctance component comprises a second bracket (not shown) and a second magnet (not shown), the front end of the first bracket is hinged with the fixed plate 12 at a fifth hinging point (not shown) so that the first reluctance component can rotate around the fifth hinging point under the action of external force (namely, the driving force from the adjusting mechanism 6) to enable the first magnet to be close to or far from the axis of the driven turntable 31 of the first tension mechanism, and the rear end of the second bracket is hinged with the fixed plate 12 at a sixth hinging point (not shown) so that the second reluctance component can rotate around the sixth hinging point (namely, the driving force from the adjusting mechanism 6) to enable the first magnet to be close to or far from the driven turntable 31 under the action of the driving force from the adjusting mechanism.

Of course, the structure of the adjusting mechanism 6 is not limited to this, and the reluctance component 32 is connected by an electric screw, so that the resistance range of the reluctance component 32 to the driven turntable 31 can be adjusted.

The reluctance component 32 may be replaced by a component composed of a support made of a magnetizing coil and a soft magnet, and the magnetic force of the reluctance component 32 to the movable turntable 31 is adjusted by adjusting the current of the magnetizing coil, so that the counterweight pulling force can be adjusted, and the chest expander does not need the adjusting mechanism 6, thereby simplifying the structure.

In another preferred embodiment, the pull-back device 2 includes a rotary disc (not shown) having a central through hole (not shown) provided therethrough, a pull cord 21, a connecting shaft (not shown) rotatably penetrating the central through hole and fixedly assembled in the flat housing 1, and a scroll spring (not shown) having one end fixed to the connecting shaft and the other end fixed to the rotary disc, the pull cord 21 wound around the rotary disc, and one end of the pull cord 21 fixed to the rotary disc and the other end connected to the guide unit 5 and extending out of the flat housing 1, the scroll spring being an elastic portion of the pull-back device 2, and the rotary disc being a rotary portion of the pull-back device 2.

When a user applies an upward pulling force to the pulling rope 21, the pulling rope 21 drives the rotary disk to rotate, and simultaneously the spiral spring of the pullback device 2 is deformed to increase the rotation torque of the spiral spring of the pullback device 2, so as to be used as a power source for reversing (namely, rotating) the rotary disk.

When the user releases the pulling force applied to the pull rope 21, the turning torque of the pullback device 2 overcomes the resistance limitation of the counterweight assembly 3 to the pullback device 2, so that the pullback disc turns, and the pull rope 21 is wound back on the pullback disc, so that the action effect that the pull rope 21 is retracted on the pullback disc in a winding manner is realized.

More specifically, the pullback device 2 and the driven turntable 31 form a transmission connection through a conveyor belt 7, so that the pullback device 2 drives the driven turntable 31 to rotate, and the driven turntable 31 is reacted to the pullback device 2 under the resistance of the reluctance component 32.

Further preferably, the tensioner further comprises a tensioner 8, the tensioner 8 being arranged in correspondence of the belt 7 to adjust the tightness of the belt 7.

In this embodiment, the tensioner 8 includes a pulley (not shown), a limit screw (not shown), a fixing frame (not shown) and a slider (not shown), the fixing frame is fixed on an inner wall surface (i.e., an inner surface of a lateral wall of the supporting frame 13 in a width direction) perpendicular to the length direction of the accommodating cavity, the slider is slidably assembled on the fixing frame, the limit screw penetrates through one end of the fixing frame, which is away from the slider, in a threaded connection manner, the limit screw penetrates through a part of the slider to be abutted on the slider, the slider is away from an end part of the limit screw to be fixedly assembled with the pulley, and a part of the pulley surface is abutted on a part of the conveyor belt 7 between the pullback device 2 and the driven turntable 31, and the slider is driven to slide back and forth on the fixing frame by adjusting a fixed position of the limit screw so as to adjust tightness of the pulley to the conveyor belt 7.

In another preferred embodiment, the guiding unit 5 includes a supporting frame 51, a limiting shaft 54, a first guiding wheel 52 and a second guiding wheel 53, the supporting frame 51 is fixedly assembled on a side wall of the accommodating cavity, the limiting shaft 54 is rotatably assembled on the supporting frame 51, the first guiding wheel 52 and the second guiding wheel 53 are assembled on the supporting frame 51, the axis of the first guiding wheel 52 and the axis of the second guiding wheel 53 are perpendicular to each other, the limiting shaft 54 corresponds to the first guiding wheel 52, the limiting shaft 54 and the wheel surface of the first guiding wheel 52 are arranged at intervals, the supporting frame 51 has a guiding through hole 511, the guiding through hole 511 is located between the second guiding wheel 53 and the first guiding wheel 52, the pull rope 21 of the pull-back device 2 is wound on a part of the wheel surface of the second guiding wheel 53, passes through the guiding through the through hole 511, and then winds on a part of the wheel surface of the first guiding wheel 52, and then passes through the first guiding wheel 52 and the flat shaft 54, and extends out of the limiting housing 1.

In specific implementation, the supporting frame 51 includes a first supporting frame (not shown) and a second supporting frame (not shown), the first guiding wheel 52 is assembled on the first supporting frame, the second guiding wheel 53 is assembled on the second supporting frame, the side wall of the accommodating cavity is the side wall of the supporting frame 13, the outer circumferential surface of the rotating disc is provided with a placing groove (not shown) for accommodating the pull rope 21, the pull rope 21 is wound in the placing groove so as to be convenient for accommodating, and the pull rope 21 is limited so as to prevent the pull rope 21 from sliding out of the rotating disc.

The second guide wheel 53 limits the pull rope 21, so that the pull rope 21 is not easy to be pulled out from the placement groove of the turntable during the process of pulling out the turntable.

The position of the pull rope 21 extending from the second guide wheel 53 is fixed by the guide through hole 511 to prevent the pull rope 21 from being easily pulled out from the wheel surface of the second guide wheel 53, and then the pull rope 21 is limited by the first guide wheel 52 to extend from the first guide wheel 52 to the upper side of the flat housing 1, so that the pull rope 21 is conveniently pulled by a user.

The pull cord 21 is simultaneously restricted on the tread of the first guide wheel 52 by the first guide wheel 52 and the restricting shaft 54, and the pull cord 21 is prevented from being easily pulled out of the tread of the first guide wheel 52 when the user performs the tension training exercise.

Of course, the structure of the guiding unit 5 is not limited thereto, and the guiding unit 5 may further include a steerable steering member fixed on the supporting frame 51, where the first guiding wheel 52 is disposed on the steering member, and the steering member may horizontally rotate relative to the supporting frame 51 to implement multi-angle drawing, so that the structure of the guiding unit 5 may be determined according to the drawing direction of the pull rope 21 by the user and different specific training manners, which will not be described herein.

While the utility model has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the utility model as defined by the appended claims.

Claims (10)

1. The utility model provides a chest expander, includes the flat casing that has the accommodation cavity and sets up direction unit and pulling force mechanism in the accommodation cavity of flat casing, its characterized in that:

the tension mechanism comprises a counterweight assembly and a pullback device, the counterweight assembly comprises a magnetic resistance assembly and a driven turntable which are matched, and the magnetic resistance assembly applies resistance to the driven turntable;

the pullback device and the driven turntable are assembled in the accommodating cavity in parallel;

the pullback device and the driven turntable form transmission connection; the pull rope of the pullback device is connected with the guide unit and extends out of the flat shell.

2. The chest expander of claim 1, wherein: the number of the tension mechanisms is two, and the two tension mechanisms are rotationally symmetrically arranged at the left side and the right side of the accommodating cavity; each tension mechanism is provided with a guide unit.

3. The chest expander of claim 2, wherein: the adjusting mechanism is arranged in the middle of the accommodating cavity and is positioned between the two tension mechanisms; the adjusting mechanism comprises a driver and a connecting unit, wherein the driver is connected with the connecting unit, and the connecting unit is connected with the magnetic resistance assembly.

4. A chest expander according to claim 3, wherein: the connecting unit comprises a connecting sheet, a connecting rod and a pull rod, wherein the connecting sheet is rotatably assembled in the middle part in the flat shell, the driver is fixedly assembled in the flat shell and is arranged in parallel with the connecting sheet front and back, one end of the connecting rod is connected with the driver, and the other end of the connecting rod is hinged with the connecting sheet; one end of the pull rod is hinged to the connecting sheet, and the other end of the pull rod is hinged to the magnetic resistance assembly.

5. The chest expander of claim 1 or 2 or 3 or 4, wherein: the reluctance assembly comprises a magnet and a bracket, the driven turntable has soft magnetism, and the bracket is hinged with the flat shell; the bracket is provided with a bracket plate and mounting lugs which are positioned at the upper end and the lower end of the bracket plate and extend outwards in a protruding mode, the two mounting lugs are arranged at intervals and are connected with the bracket plate to form a containing groove, and the magnet is fixedly assembled on the mounting lugs; and a part of the driven turntable is inserted into the accommodating groove.

6. The chest expander of claim 1, wherein: the pull-back device comprises a rotary disc, a pull rope, a connecting shaft and a scroll spring, wherein the rotary disc is provided with a central through hole which is penetrated, the connecting shaft can be rotatably penetrated through the central through hole and is fixedly assembled in the flat shell, one end of the scroll spring is fixed on the connecting shaft, and the other end of the scroll spring is fixed on the rotary disc; the stay cord twine in the gyration dish, just the one end of stay cord is fixed on the gyration dish, the other end is connected the guide unit and extend to outside the flat shell.

7. The chest expander of claim 1, wherein: the pullback device and the driven turntable form transmission connection through a conveyor belt.

8. The chest expander of claim 7, wherein: the conveyor belt is characterized by further comprising a tensioner which is arranged corresponding to the conveyor belt so as to adjust the tightness of the conveyor belt.

9. The chest expander of claim 1, wherein: the guide unit comprises a support frame, a limiting shaft, a first guide wheel and a second guide wheel, wherein the support frame is fixedly assembled on the side wall of the accommodating cavity, the limiting shaft is rotatably assembled on the support frame, the first guide wheel and the second guide wheel are assembled on the support frame, and the axis of the first guide wheel and the axis of the second guide wheel are mutually perpendicular; the limiting shaft corresponds to the first guide wheel, and the limiting shaft and the wheel surface of the first guide wheel are arranged at intervals; the support frame is provided with a guide through hole, and the guide through hole is positioned between the second guide wheel and the first guide wheel; the pull rope of the pull-back device passes through the guide through hole after being wound on part of the wheel surface of the second guide wheel, then passes through the gap between the first guide wheel and the limiting shaft after being wound on part of the wheel surface of the first guide wheel, and then extends out of the flat shell.

10. The chest expander of claim 1, wherein: the flat shell comprises a mounting frame and a supporting frame with a hollowed middle, the guide unit is assembled on the supporting frame, the mounting frame comprises an upper mounting plate and a lower mounting plate, the upper mounting plate and the lower mounting plate are respectively and fixedly assembled in openings on the upper side and the lower side of the supporting frame, and the openings and the supporting frame are jointly surrounded to form the accommodating cavity.