Patent Publication Number: US-2020277174-A1

Title: Hand lift device

Description:
TECHNICAL FIELD 
     The present invention relates to a hand lift device and more particularly, to a hand lift device capable of loading boxed cargo. 
     BACKGROUND ART 
     In general, a hand lift device (a hand truck, a deck truck, etc.) is intended to load and carry heavy cargo. In the hand lift device, a method of loading the cargo on a loading plate, laying the loading plate at a certain angle and then carrying the cargo to a certain distance by using wheels, and a method of lifting up and down the loading plate for loading the cargo are used. 
     In a hand lift device in the related art, there is a problem in that an operator needs to load cargo by bending the body when loading the cargo on a loading plate that initially descends to the bottom in a process of loading multiple cargo on the loading plate and bends or stretches the body while loading the cargo in sequence to damage the body. On the other hand, there is also a problem in that even when the multiple cargo loaded on the loading plate of the hand lift device is unloaded, the operator bends or stretches the body to transfer the cargo. 
     In addition, the hand lift device needs to be laid down at a certain angle to carry the multiple loaded cargo, but due to the weight of the multiple cargo loaded on the hand lift device, the old and the infirm such as women are not easy to lay at a certain angle or directly stand the hand lift device. 
     As a prior art related with the present invention, Prior Art 1 discloses a hand truck capable of stably moving upward or downward cargo by rotatably climbing a climbing unit through internal power at a place where steps are formed at a regular height, such as stairs while moving in a stable structure by wheels and a climbing auxiliary unit in a flatland when moving cargo loaded on the hand truck. In the Prior Art 1, when the cargo moves from a high position to a low position or from the low position to the high position, a lift unit is provided, but the disclosed hand truck has a disadvantage that the structure is complicated, a self-weight is large, and a manufacturing cost is high. 
     Further, as the prior art related with the present invention, Prior Art 2 discloses a hand car having a driving function of moving the hand car forward or backward by power of a motor and a lifting function of lifting up or down a loading plate. 
     In the Prior Art 2, when the cargo moves from a high position to a low position or from the low position to the high position, a lift unit is provided, but when high-weight cargo is placed on the loading plate, a structure for firmly supporting a chain that gives the lift function is not separately provided and thus there is a limit in the load stability. 
     DISCLOSURE 
     Technical Problem 
     The present invention has been made to solve the above problems, and an object of the present invention is to provide a hand lift device in which a cargo loading unit is automatically lifted up or down to maintain loaded cargo at a predetermined height by detecting a height of the cargo loaded on the cargo loading unit so that an operator can load or lift up the cargo without bending the body. 
     Another object of the present invention is to provide a hand lift device in which even when high-weight loaded cargo is loaded on the cargo loading unit, a means of adding tension to a chain for lifting up or down the cargo loading unit is provided to adjust the tension of the chain and enhance the loading stability. 
     Yet another object of the present invention is to provide a hand lift device in which the cargo loading unit is detachably configured and a detachment method is simply configured to deviate from an inconvenient detachment method such as a conventional screw coupling method, thereby improving convenience of the user. 
     The objects of the present invention are not limited to the aforementioned object, and other objects, which are not mentioned above, will be apparent to a person having ordinary skill in the art from the following description. 
     Technical Solution 
     In order to achieve the above object, an exemplary embodiment of the present invention provides a hand lift device including: a frame portion including a vertical frame, a first sprocket installed on an upper end of the vertical frame, and a second sprocket installed on a lower end of the vertical frame; a chain installed to engage with the first sprocket and the second sprocket; a cargo loading unit which is connected with the chain and disposed to be liftable along the vertical frame to load cargo; a power transmission portion which provides a driving force to the chain so that the cargo loading unit is lifted up and down; a sensor portion which is installed in an area where the frame portion is formed to be positioned at an upper side in a range where the cargo loading unit is lifted up and down and includes a proximity sensor to sense the cargo loaded on the cargo loading unit; and a controller which controls lifting up and down of the cargo loading unit by adjusting the driving of the power transmission portion according to a sensing signal from the sensor portion. 
     The transmission portion may include an electric motor rotating forward and backward, and a driving shaft of the electric motor may provide a driving force to a rotational shaft of the second sprocket. 
     The cargo loading unit may include a loading member on which the cargo is loaded, a lifting member that lifts up and down along a guide rail formed on the vertical frame, and a coupling member that couples the loading member and the lifting member, and the chain may be connected to the lifting member and transmit a driving force from the power transmission portion to the cargo loading unit through the lifting member. 
     One end of the chain may be connected to the upper end of the lifting member, the other end of the chain may be connected to the lower end of the lifting member, and a chain tensioner providing the tension to the chain may be interposed in at least one point of points where the chain and the lifting member are connected. 
     The chain tensioner may be formed of a spring member in which both ends have a ring shape, one end is connected to the chain, and the other end is connected to the lifting member, or formed in an elastic structure which includes a support panel fastened to the lifting member, a chain connection portion of which one side is exposed outside the support panel through the support panel to be coupled to the chain and the other side is accommodated inside the lifting member, and a spring member elastically supporting the chain connection portion while being accommodated inside the lifting member, interposed between the chain connection portion and the support panel, and supported by the support panel. 
     The lifting member may include at least one protrusion, and the coupling member may include at least one engaging portion formed to engage with the protrusion. 
     The controller may control the driving of the power transmission portion to maintain a height of the upper end of the cargo loaded on the cargo loading unit at a predetermined height based on the sensing signal from the sensor portion. 
     The controller may control the lifting of the cargo loading unit by maintaining the driving of the power transmission portion when the cargo sensing signal is received from the sensor portion in the case of a load mode of driving the power transmission portion so that the cargo loading unit is lifted down, and stopping the driving of the power transmission portion when the cargo sensing signal is received from the sensor portion in the case of an unload mode of driving the power transmission portion so that the cargo loading unit is lifted up. 
     The sensor portion may further include a load cell which is installed on the cargo loading unit to sense the load of the cargo loaded on the cargo loading unit. 
     The hand lift device may further include a moving support portion which is detachably installed on the frame portion to support the frame portion and moves the frame portion to a predetermined position. 
     The moving support portion may include a frame support structure which has a slot which can accommodate a part of the frame portion therein to support the outer surface of the frame portion accommodated in the slot and is detachably coupled to the frame portion; support panels which are coupled to both ends of the frame support structure in a longitudinal direction of the frame support structure; wheels which are coupled to the support panels and are arranged behind the frame portion and perform rotational motion in a state of being grounded on the ground surface; and forks which are coupled to the support panel and disposed in front of the frame portion and have a caster at the end to switch the movement direction of the frame portion. 
     The support panel may be formed of a magnesium material, and the fork may be position-adjustable in a front-rear direction of the frame portion along the surface of the support panel. 
     The wheel may include a wheel motor which is coupled and supported to the support panel to generate a rotational force; and a wheel body which is rotatably coupled to the wheel motor and performs rotational motion through the rotational force transmitted from the wheel motor. 
     The hand lift device may further include a fixing support portion which is detachably installed on the frame portion and supported on the ground to support the frame portion in a direction perpendicular to the ground surface. 
     The fixing support portion may include a fixing panel formed in a flat plate and installed on the ground; and a vertical support frame which protrudes upward by a predetermined length in the vertical direction from the upper surface of the fixing panel to form a slot capable of accommodating a part of the frame portion therein and support the outer surface of the frame portion accommodated in the slot. 
     The vertical support frame may simultaneously support both side surfaces and the rear surface of the frame portion accommodated in the slot. 
     The hand lift device may further include a boarding portion which is installed on the frame portion and boardable while a user is standing or sitting. 
     The cargo loading unit may include a support frame which is installed on the frame portion to be lifted up and down; support arms which protrude from the end of the support frame in a predetermined length to form an accommodation space capable of accommodating the cargo therein and are disposed opposite to each other in the longitudinal direction of the support frame; and gripping blades which are rotatably installed on the support arms and disposed in the accommodation space in a horizontal state, and separated outwardly by rotating at a predetermined angle when the cargo is loaded and then retracted inwardly by an elastic force to support the outer surface of the cargo. 
     The support frame may include a vertical member which is installed on the frame portion; a horizontal member which is disposed horizontally below the vertical member and connected to the support arm to support the support arm; and a reinforcement member connecting the vertical member and the horizontal member. 
     The support arms may include a first arm disposed on one side of the horizontal member in a longitudinal direction of the horizontal member and a second arm disposed on the other side of the horizontal member in the longitudinal direction of the horizontal member, and the gripping blades may include a first blade rotatably installed on the first arm and a second blade rotatably installed on the second arm. 
     The first arm and the second arm may be coupled to the horizontal member in a detachable structure and relatively movable in the longitudinal direction of the horizontal member. 
     The support arms may be installed on the first arm and the second arm to support the first blade and the second blade, respectively, and further include grip space adjusting units which relatively move the first blade and the second blade to adjust a distance between the first blade and the second blade. 
     The grip space adjusting unit may include a guide rail provided on the upper surface of the support arm; a transport block provided on the guide rail and movable along the guide rail; a support bracket provided on the transport block and rotatably supporting the gripping blade; and a driving device which is provided on the upper surface of the support arm and coupled to the support bracket to move the support bracket. 
     When the cargo is unloaded, a distance between the first blade and the second blade may be smaller than a distance between the first blade and the outer surface of the cargo supported by the second blade. 
     The gripping blade may include a shaft portion rotatably coupled to the support arm; a blade body which extends from the shaft portion to one side to be disposed in the accommodation space and has a plurality of inclined guide surfaces formed on one side end and the other side end of the blade body in the longitudinal direction to guide the movement of the cargo when the cargo is loaded; and an elastic member which is provided around the shaft portion to elastically support the blade body and limits a rotational angle of the gripping blade. 
     The gripping blade may be rotatable at an angle of 0° to 90°. 
     The gripping blade may further include a guide roller which is installed on the end portion of the blade body and performs the rotational motion while being in contact with the outer surface of the cargo when the cargo is loaded. 
     The cargo loading unit may include a support frame which is installed on the frame portion to be lifted up and down; a driving portion which is installed on the support portion and extendable or contractible by performing linear motion in a horizontal direction; and a gripping portion which is rotatably coupled to both ends of the driving portion, forms an accommodation space capable of accommodating the cargo therein, and grips the cargo accommodated in the accommodation space by performing relative motion in the horizontal direction when the driving portion is driven. 
     The gripping portion may include a first support arm rotatably installed on one side of the driving portion; and a second support arm rotatably installed on the other side of the driving portion and disposed to face the first support arm to perform relative motion with respect to the first support arm. 
     The hand lift device may further include a cushioning portion provided on the support portion and supporting the gripping portion in the horizontal direction. 
     The cargo loading unit may include a support frame which is installed on the frame portion to be lifted up and down; a tongs-shaped gripping portion which is rotatably installed on the support portion to form an accommodation space therein and grips the cargo accommodated in the accommodation portion while being separated outwardly or retracted inwardly during rotating; and a driving portion which is installed on the support portion to be connected to the end portion of the gripping portion accommodated in the support portion and pushes outwardly or pulls inwardly the end portion of the gripping portion by performing linear motion to adjust a rotational angle of the gripping portion. 
     The cargo loading unit may include a support frame which is installed on the frame portion to be lifted up and down; a rotation portion installed on the support portion and rotatable clockwise or counterclockwise; a tongs-shaped gripping portion which is installed on the rotation portion to form an accommodation space therein and separated outwardly or retracted inwardly by rotation and presses and supports the outer surface of the cargo accommodated in the accommodation space; and a driving portion including a first angle adjusting unit which is installed on the rotation portion and transmits a rotational force to the gripping portion to adjust a rotational angle of the gripping portion, and a second angle adjusting unit which is installed on the support portion and transmits a rotational force to the rotation portion to adjust a rotational angle of the rotation portion. 
     The support portion may include a support member which is axially coupled to the rotation portion to rotatably support the rotation portion; a lifting member which is installed on the frame portion to be lifted up and down; and a coupling member connecting the support member and the lifting member. 
     The rotation portion may include a bracket which forms an accommodation space capable of accommodating the gripping portion and the first angle adjusting unit therein and is rotatably coupled to the support member to be rotatable clockwise or counterclockwise on one surface of the support member when the second angle adjusting unit is driven; a driven gear provided between the bracket and the support member; a gear fixing member protruding outward from the bracket to fix the driven gear to the outer surface of the bracket; and a diaphragm provided on an inner surface of the bracket to divide a space in the bracket into a plurality of spaces. 
     The gripping portion may include a first support arm rotatably installed on one side of the bracket and a second support arm rotatably installed on the other side of the bracket and disposed opposite to the first support arm, and the first support arm and the second support arm may include a rotational shaft portion rotatably installed on the bracket and disposed in an inner space of the bracket; and a gripping body which is coupled with the rotational shaft portion to be disposed in an outer space of the bracket and separated outwardly or retracted inwardly by rotating together with the rotational shaft portion according to the driving of the first angle adjusting unit. 
     The first angle adjusting unit may include a first arm controller which is installed inside the bracket to rotate the first support arm and a second arm controller which is installed inside the bracket and disposed opposite to the first arm controller to rotate the second support arm, and the second angle adjusting unit may be installed on the support member and transmits the rotational force to the driven gear to rotate the bracket. 
     The first arm controller and the second arm controller may include a first power transmission gear which is installed around the rotational shaft portion to be rotatable together with the rotational shaft portion; a second power transmission gear which is rotatably installed inside the bracket and transmits the rotational force to the first power transmission gear to rotate the first power transmission gear; and a first driving device which is installed inside the bracket to be connected with the second power transmission gear and performs linear motion to rotate the second power transmission gear clockwise or counterclockwise. 
     The first driving device may include a linear actuator which is installed inside the bracket and performs linear motion in a longitudinal direction of the bracket; and a third power transmission gear which is installed on the linear actuator to be gear-engaged with the second power transmission gear and linearly moves to one side or the other side when the linear actuator is driven to rotate the second power transmission gear. 
     Effect 
     According to the embodiment of the present invention, since the operator can automatically load the cargo by controlling the cargo loading unit without manually loading the cargo, the hand lift device can operate faster than manual operation, load more cargo over the same time, and operate with a small number of persons, thereby reducing the cost. 
     Further, the proximity sensor for sensing the height of the cargo loaded on the cargo loading unit is provided and the loaded cargo is maintained at a predetermined height through the driving of the automatic operation mode, so that the operator can load or unload the cargo without bending the back, thereby solving the problem of chronic back pain of the operators who perform the simple repetition of the unloading operation and improving the operation efficiency of the operator. 
     Further, a means for applying a tension to the chain for lifting the cargo loading unit is provided to adjust the tension of the chain even when high-weight loaded cargo is loaded on the cargo loading unit, thereby increasing loading stability. 
     Further, the cargo loading unit is configured to be attached or detached and the attaching or detaching method is simply configured to deviate from an inconvenient attaching or detaching method such as a screw coupling method in the related art, thereby efficiently improving convenience of the operator. 
     Further, a gripping blade which is pressed against the outer surface of the cargo when the cargo is loaded on the cargo loading unit to be separated outwardly and then automatically retracted inwardly by an elastic force to support the outer surface of the cargo is provided, so that the operator can automatically load the cargo only by an operation of sliding the gripping blade to the outer surface of the cargo through the movement of the hand lift device without loading the cargo manually, thereby shortening significantly a cargo loading time and improving workability. 
     Further, when the cargo loading unit is lifted up through the hand lift device, the load acting on the cargo in the vertical direction is added to the gripping blade that supports the stepped portion of the cargo, and thus the gripping blade is further retracted inwardly toward the outer surface of the cargo, thereby strengthening the supporting force acting on the cargo and more stably fixing the cargo. 
     Further, the cargo loading unit includes a tongs-shaped gripping portion capable of gripping the cargo by adjusting the accommodation space through the relative motion, thereby easily gripping and loading the cargo having various sizes and shapes. 
     Further, since the cargo loading unit is provided with the rotation portion which is rotatable clockwise or counterclockwise, the cargo can be gripped at various positions, thereby increasing the usability and efficiently loading various types of cargo. 
     Further, the cargo loading unit includes the driving portion to which the linear actuator is applied to control the gripping portion, and thus the pressing force suitable for the cargo is finely adjusted according to the shape of the cargo, the material of the cargo or the hardness of the cargo, thereby stably loading the cargo. 
     Further, the loaded cargo can move in front, rear, left, right, upper and lower directions by the cargo loading unit and the moving support portion, thereby stably carrying and unloading the loaded cargo at various positions. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view illustrating a hand lift device according to an embodiment of the present invention. 
         FIG. 2  is a schematic side view illustrating the hand lift device according to the embodiment of the present invention. 
         FIG. 3  is a side view schematically illustrating an internal structure of the hand lift device according to the embodiment of the present invention. 
         FIG. 4  is an enlarged perspective view illustrating one section of the hand lift device according to the embodiment of the present invention. 
         FIG. 5  is an exploded perspective view illustrating a state in which a moving support portion is separated from a frame portion of the hand lift device according to the embodiment of the present invention. 
         FIG. 6  is a side view illustrating a state in which a fixing support portion is installed on the frame portion of the hand lift device according to the embodiment of the present invention. 
         FIG. 7  is a side view schematically illustrating a state in which a boarding portion is installed on the hand lift device according to the embodiment of the present invention. 
         FIG. 8  is a perspective view illustrating a hand lift device according to another embodiment of the present invention. 
         FIG. 9  is a side view schematically illustrating the hand lift device according to another embodiment of the present invention. 
         FIG. 10  is a side view schematically illustrating a driving method of the hand lift device according to another embodiment of the present invention. 
         FIG. 11  is a perspective view illustrating a part of the hand lift device according to another embodiment of the present invention to which a cargo loading unit is applied. 
         FIG. 12  is a perspective view illustrating a hand lift device according to yet another embodiment of the present invention to which a cargo loading unit is applied. 
         FIG. 13  is a perspective view illustrating the cargo loading unit illustrated in  FIG. 12 . 
         FIG. 14  is a cross-sectional view schematically illustrating a state in which a first blade is installed on a first arm of the cargo loading unit according to yet another embodiment of the present invention. 
         FIG. 15  is a plan view schematically illustrating a state in which a first arm and a second arm are installed on a horizontal member of the cargo loading unit according to yet another embodiment of the present invention. 
         FIG. 16  is a view schematically illustrating a state in which a first blade is installed on a first arm by a grip space adjusting unit in the cargo loading unit according to yet another embodiment of the present invention. 
         FIG. 17  is a plan view schematically illustrating a state in which cargo is not loaded on the cargo loading unit according to yet another embodiment of the present invention. 
         FIG. 18  is a view schematically illustrating a process in which cargo is loaded on the cargo loading unit according to yet another embodiment of the present invention. 
         FIG. 19  is a view schematically illustrating a state in which a guide roller is installed on a blade body of the cargo loading unit according to yet another embodiment of the present invention. 
         FIG. 20  is a perspective view illustrating a hand lift device according to still another embodiment of the present invention to which a cargo loading unit is applied. 
         FIG. 21  is a view schematically illustrating the cargo loading unit illustrated in  FIG. 20 . 
         FIG. 22  is a view schematically illustrating a modified example of the cargo loading unit according to still another embodiment of the present invention. 
         FIG. 23  is a view schematically illustrating another modified example of the cargo loading unit according to still another embodiment of the present invention. 
         FIG. 24  is a view schematically illustrating a first angle adjusting unit of the cargo loading unit of  FIG. 23 . 
         FIG. 25  is a view schematically illustrating another form of a chain tensioner. 
     
    
    
     BEST MODE 
     Hereinafter, various embodiments will be described in detail with reference to the accompanying drawings. The embodiments described in this specification may be variously modified. Specific embodiments are described in the drawings and may be described in detail in the detailed description. It should be understood, however, that the specific embodiments disclosed in the accompanying drawings are intended only to facilitate understanding of various embodiments. Accordingly, it is to be understood that the technical idea is not limited by the specific embodiments disclosed in the accompanying drawings, but includes all equivalents or alternatives included within the spirit and scope of the invention. 
     Terms including an ordinary number, such as first and second, are used for describing various constituent elements, but the constituent elements are not limited by the terms. The above terminologies are used only to discriminate one component from the other component. 
     In the present application, it should be understood that term “include” or “have” indicates that a feature, a number, a step, an operation, a component, a part or the combination thereof described in the specification is present, but does not exclude a possibility of presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations, in advance. It should be understood that, when it is described that an element is “coupled” or “connected” to another element, the element may be “directly coupled” or “directly connected” to the another element or “coupled” or “connected” to the another element through a third element. In contrast, it should be understood that, when it is described that an element is “directly coupled” or “directly connected” to another element, it is understood that no element is present between the element and the another element. 
     Meanwhile, the “module” or “portion” for the component used in this specification performs at least one function or operation. In addition, the “module” or “portion” may perform a function or operation by hardware, software, or a combination of hardware and software. Also, a plurality of “modules” or a plurality of “portions” except for the “module” or “portion” performed in specific hardware or performed in at least one processor may be combined into at least one module. A singular form may include a plural form if there is no clearly opposite meaning in the context. 
     In describing the present disclosure, a detailed explanation of known related technologies may be omitted to avoid unnecessarily obscuring the subject matter of the present disclosure. 
       FIG. 1  is a perspective view illustrating a hand lift device according to an embodiment of the present invention,  FIG. 2  is a schematic side view illustrating the hand lift device according to the embodiment of the present invention,  FIG. 3  is a side view schematically illustrating an internal structure of the hand lift device according to the embodiment of the present invention, and  FIG. 4  is an enlarged perspective view illustrating one section of the hand lift device according to the embodiment of the present invention. 
     Referring to  FIGS. 1, 2, and 3 , a hand lift device  2  (hereinafter, referred to as the ‘hand lift device  2 ’) according to the embodiment of the present invention includes a frame portion  21 , a chain  22  disposed in a longitudinal direction of the frame portion  21 , a cargo loading unit  1  configured to be connected to the chain  22  to load cargo, a power transmission portion  24  providing a driving force to the chain  22 , a sensor portion  25  sensing cargo (not illustrated) loaded on the cargo loading unit  1 , and a controller  26  controlling driving of the power transmission portion  24  according to a sensing signal from the sensor portion  25 . 
     The frame portion  21  includes a vertical frame  211 , a first sprocket  212 , and a second sprocket  213 . 
     A guide rail  214  is formed inside the vertical frame  211 , the first sprocket  212  is disposed on the upper side of the vertical frame  211 , and the second sprocket  213  is disposed on the lower side of the vertical frame  211 . 
     The chain  22  is installed to engage with the first sprocket  212  and the second sprocket  213 . The first sprocket  212  and the second sprocket  113  function as pulleys for supporting the chain  22  at the upper and lower ends of the vertical frame  211 , respectively. The first sprocket  212  and the second sprocket  213  are preferably installed on the vertical frame  211  so as to be symmetrically positioned at positions facing each other, respectively. 
     The chain  22  receives the driving force from the power transmission portion  24  to be described below to rotate by engaging with the first sprocket  212  and the second sprocket  213 . 
     The cargo loading unit  1  is configured to be connected to the chain  22  and move up and down along the guide rail  214  connected to the chain  22  and formed in the vertical frame  211 . In addition, the cargo loading unit  1  is configured so that the chain  22  is connected to the rear surface of the cargo loading unit  1  and the cargo is loaded on the front side of the cargo loading unit  1 . 
     Referring to  FIG. 4 , the cargo loading unit  1  may include a loading member  16  on which the cargo is loaded, a lifting member  14  which is connected to the chain  22  to lift up and down along the guide rail  214  formed on the vertical frame  211  when the chain  22  moves, and a coupling member  15  connecting the loading member  16  and the lifting member  14 . 
     The loading member  16  may include a vertical panel  16   a  coupled to the lifting member  14  by the coupling member  15  and a horizontal panel  16   b  formed in a flat plate shape to load the cargo. The vertical panel  16   a  and the horizontal panel  16   b  may be formed to be substantially at a right angle. 
     Here, at least one protruding portion  14   a  is formed on the lifting member  14  and at least one engaging portion  15   a  formed to engage with the protruding portion  14   a  is formed on the coupling member  15  so that the protruding portion  14   a  and the engaging portion  15   a  may be coupled to each other by a female-male fitting method. Accordingly, unlike a conventional bolt-nut coupling method in which a plurality of structures is connected to each other using a separate fastening tool, the cargo loading unit  1  may be rapidly attached or detached to or from the hand lift device  2  without a separate tool and the cargo loading unit  1  may be firmly fixed to the hand lift device  2 . However, the cargo loading unit  1  is not limited to those illustrated in  FIGS. 1 and 4 , and may be applied in various shapes. This will be described later. 
     The power transmission portion  24  includes an electric motor  241 . The electric motor  241  is preferably a brushless motor, and in addition, as the electric motor  241 , various known motors such as a stepping motor and a servo motor may be applied. 
     Referring to  FIG. 3 , a drive shaft of the electric motor  241  rotates by engaging with the second sprocket  213  and provides a driving force to the chain  22 . The chain  22  is sequentially gear-coupled to the first sprocket  212  and the second sprocket  213  and the driving force generated from the electric motor  241  is transmitted to the chain  22  through the second sprocket  213 . 
     The chain  22  is connected to the lifting member  14  and transmits the driving force from the power transmission portion  24  to the cargo loading unit  1  through the lifting member  14 . Specifically, one end of the chain  22  may be connected to the upper end of the lifting member  14 , and the other end of the chain  22  may be connected to the lower end of the lifting member  14 . 
     At this time, a chain tensioner  221  to provide tension to the chain may be interposed in at least one of the points where the chain  22  and the lifting member  14  are connected. 
     The chain tensioner  221  is a spring member having self-elasticity, and both end portions may be formed in an annular shape. The chain tensioner  221  has one end connected to the chain  22  and the other end connected to the lifting member  14  to apply tension to the chain  22  while mediating the connection between the chain  22  and the lifting member  14 . The chain tensioner  221  serves to keep the tension of the chain  22  at a predetermined level or more. When a heavy load is applied to the cargo loading unit  1 , the chain  22  may temporarily be sagged. At this time, the chain tensioner  221  may compensate for the sagging of the chain  22  using self-elasticity. 
     Meanwhile, the chain tensioner  221  may be formed in the form of an elastic structure that is coupled to the lifting member  14  and generates a predetermined elastic force to provide the tension to the chain  22 . 
     Referring to  FIG. 25 , the chain tensioner  221  may include a support panel  2211  fastened to the lifting member  14  through a plurality of fastening means, a chain connection portion  2212  of which one side is exposed outside the support panel  2211  through the support panel  2211  to be coupled to the chain  22  and the other side is accommodated inside the lifting member  14 , and a spring member  2213  elastically supporting the chain connection portion  2212  while being accommodated inside the lifting member  14 , interposed between the chain connection portion  2212  and the support panel  2211 , and supported by the support panel  2211 . Herein, the chain connection portion  2212  may be formed in a structure having a bolt portion connected to the chain  22  and a nut portion fastened to one side of the bolt portion and elastically supported by the spring member  2213 . Accordingly, the tension transmitted to the chain  22  may be adjusted through a process of tightening or loosening the bolt portion to which the chain  22  is connected. In addition, the spring member  2213  is interposed between the chain connection portion  2212  and the support panel  2211  so as to apply a reaction force in an opposite direction while being supported by the support panel  2211  to prevent the spring member from stretching indefinitely and prevent the chain from sagging even when the cargo having a limited weight or more is loaded. 
     However, the chain tensioner  221  is not necessarily limited thereto, and may be modified into various structures and shapes as long as it can compensate for the sagging of the chain  22 . 
     Therefore, the hand lift device  2  is provided with a means for applying tension to the chains  22  and  32  for lifting up and down the cargo loading unit  1 , thereby increasing the loading stability by adjusting the tension of the chain  22  even when the high-weight cargo is loaded on the cargo loading unit  1 . 
     On the other hand, a decelerator (not illustrated) for reducing the rotational force of the electric motor  241  may be further selectively provided between the electric motor  241  and the chain  22 . In this case, the rotational force of the electric motor  241  is transmitted to the chain  22  via the decelerator. Further, a worm (not illustrated) and a worm gear (not illustrated) may be included between the driving shaft of the electric motor  241  and the rotating shaft of the second sprocket  213 , respectively. 
     Referring back to  FIGS. 1 and 2 , the sensor portion  25  senses the cargo loaded on the cargo loading unit  1 . Specifically, the sensor portion  25  includes a proximity sensor  251  for sensing the cargo loaded on the cargo loading unit  1  and a sensor support portion  152  for supporting the proximity sensor  251 . 
     The proximity sensor  251  is a sensor for sensing an object when an object (cargo in the present invention) approaches, and various known proximity sensors such as a hall sensor and an optical sensor may be used. 
     The proximity sensor  251  is guided to move in a longitudinal direction of the vertical frame  211  in the range of both ends of a sensor guide  252 . At this time, even if the proximity sensor  251  is located at the lowermost position of the sensor guide  252 , it is preferable that the proximity sensor  251  is disposed at an upper side of a range in which the cargo loading unit  1  is lifted up and down. The sensor guide  252  may be configured in the form of a bracket to be detachable at any point of the vertical frame  211 . The proximity sensor  251  may move along a slot formed in the sensor guide  252  and may also be fixed by various attachment means such as a magnet. 
     In addition, the sensor portion  25  may further include a load cell  253 . 
     Referring to  FIG. 1 , the load cell  253  is installed on the cargo loading unit  1 , and may detect the load of the cargo loaded on the cargo loading unit  1  to transmit a signal of the detected load to the controller  26  to be described below. 
     The controller  26  controls the lifting of the cargo loading unit  1  based on the cargo sensing signal from the sensor portion  25 . Accordingly, the hand lift device  2  automatically adjusts the height of the cargo loading unit  1  according to the height of the loaded cargo or the load of the cargo. 
     Specifically, the controller  26  controls the lifting of the cargo loading unit  1  by controlling the driving of the power transmission portion  24  in accordance with the sensing signal transmitted from the proximity sensor  251  of the sensor portion  25 . 
     That is, the controller  26  controls the driving of the power transmission portion  24  to maintain the height of the upper end of the cargo loaded on the cargo loading unit  1  at a predetermined height, based on the cargo sensing signal from the sensor portion  25 . 
     Specifically, the controller  26  may transmit control commands to each configuration so as to operate in a ‘load mode’ of loading the cargo and an ‘unload mode’ of unloading the cargo. 
     The ‘load mode’ is an automatic operation mode when the operator loads the cargo on the cargo loading unit  1 . When a plurality of cargo is loaded, an operator typically loads one cargo and loads the next cargo on top of the cargo. In order to load the next cargo, the operator loads the next cargo by a height higher than the previously loaded cargo. At this time, a large load is applied to the back of the operator. 
     Therefore, in order to allow the operator to constantly maintain the height at which the cargo is lifted when the operator loads a plurality of cargo, the hand lift device  2  controls the driving of the power transmission portion  24  so that the cargo loading unit  1  is lifted down by the height of the previously loaded cargo. At this time, the controller  26  maintains the driving the power transmission portion  24  when the cargo sensing signal is received from the sensor portion  25 , and stops the driving the power transmission portion  24  when the receiving of the cargo sensing signal from the sensor unit  25  is stopped. 
     The ‘unload mode’ is an automatic operation mode when the operator unloads the cargo from the cargo loading unit  1 . When the plurality of cargo is unloaded, generally, the operator unloads one cargo and then unloads the next cargo below the cargo thereof. In order to unload the next cargo, the operator unloads the next cargo by bending the back at a height lower than the previously unloaded cargo. At this time, a large load is applied to the back of the operator. 
     Therefore, in order to allow the operator to constantly maintain the height at which the cargo is lifted when the operator unloads the plurality of cargo, the hand lift device  2  controls the driving of the power transmission portion  24  so that the cargo loading unit  1  is lifted up by the height of the previously unloaded cargo. At this time, the controller  26  maintains the driving the power transmission portion  24  when the cargo sensing signal is not received from the sensor portion  25 , and stops the driving the power transmission portion  24  when the cargo sensing signal is received from the sensor unit  25 . 
     That is, the hand lift device  2  is provided with the proximity sensor  251  for sensing the height of the cargo loaded on the cargo loading unit  1  and allows the loaded cargo to be maintained at a predetermined height through the driving of the above-described automatic operation mode (load mode or unload mode), thereby loading or unloading the cargo without bending the back of the operator. Thus, the hand lift device  2  may not only solve the problem of the chronic back pain of the operators who perform the conventional simple repetition of loading and unloading but also significantly contribute to the operation efficiency of the operators. 
     Further, the controller  26  controls the lifting of the cargo loading unit  1  by controlling the driving of the power transmission portion  24  in accordance with the sensing signal transmitted from the load cell  253  of the sensor portion  25 . 
     That is, according to the selected drive mode, the controller  26  compares the cargo sensing signal transmitted from the sensor portion  25 , that is, the signal relating to the load of the cargo loaded on the cargo loading unit  1 , with a predetermined reference signal to control the driving of the power transmission portion  24  and maintain the height of the upper end of the cargo loaded on the cargo loading unit  1  at a predetermined height. 
     Specifically, in the ‘load mode’ in which the power transmission unit  24  is driven so that the cargo loading unit  1  is lifted down, the controller  26  compares the cargo sensing signal received from the sensor portion  25  with a preset first reference signal in real time and maintains the driving of the power transmission portion  24  until the cargo sensing signal reaches the first reference signal. Here, the first reference signal may be set to a signal corresponding to the total load of the cargo to be loaded. 
     On the contrary, in the ‘unload mode’ in which the power transmission unit  24  is driven so that the cargo loading unit  1  is lifted up, the controller  26  compares the cargo sensing signal received from the sensor portion  25  with a preset second reference signal in real time and maintains the driving of the power transmission portion  24  until the cargo sensing signal reaches the second reference signal. Here, the second reference signal may be set to a signal corresponding to a value of zero. 
     In addition, the hand lift device  2  may include a control portion  27  configured to allow an operator to control the operation of the hand lift device  2 . 
     The control portion  27  includes a power supply switch capable of turning on/off the operating power of the electric motor  241 , a joystick capable of lifting up the cargo loading unit  1  to an arbitrary position, a manual operation switch for setting the hand lift device  2  to operate in a manual mode, an automatic operation switch for automatically setting the power transmission portion  24  to be controlled based on the sensing signal from the sensor portion  25 , and the like. However, the control portion  27  is not limited thereto, and may further include various control means for controlling the hand lift device  2 . 
     In addition, the hand lift device  2  includes a battery  216  for supplying power. The battery  216  may be accommodated below the hand lift device  2  together with the controller  26 . 
     Further, the hand lift device  2  of the present invention may further include a moving support portion  28 . 
       FIG. 5  is an exploded perspective view illustrating a state in which the moving support portion  28  is separated from the frame portion  21  of the hand lift device  2  according to the embodiment of the present invention. 
     Referring to  FIGS. 1 and 5 , the moving support portion  28  is detachably mounted on the frame portion  21  to support the frame portion  21  and move the frame portion  21  to a predetermined position. 
     The moving support portion  28  may include a frame support structure  281 , a pair of support panels  282 , a pair of wheels  283 , and a pair of forks  284 . 
     The frame support structure  281  has a slot  281   a  which can accommodate a part of the frame portion  21  therein to support the outer surface of the frame portion  21  accommodated in the slot  281   a  and may be detachably coupled to the frame portion  21 . For example, the frame support structure  281  may be detachably coupled to the frame portion  21  using a separate fastening means such as bolts and nuts. 
     The pair of support panels  282  is coupled to both ends of the frame support structure  281  in a longitudinal direction of the frame support structure  281 , respectively, and is coupled to the pair of wheels  283  and the pair of forks  284  to be described below to support the pair of wheels  283  and the pair of forks  284 . For example, the pair of support panels  282  may be coupled to both ends of the frame support structure  281  using a separate fastening means such as bolts and nuts, respectively, and the pair of support panels  282  may have a plurality of fastening holes for fastening. 
     Further, the pair of support panels  282  may be formed of a non-ferrous metal material. 
     More specifically, the pair of support panels  282  may be formed of a magnesium material having a predetermined thickness. However, the pair of support panels  282  is not necessarily limited to the material thereof, and may be formed of aluminum or a magnesium alloy which contains magnesium as a main component, if necessary. 
     The pair of wheels  283  is coupled to the support panels  282  and is arranged behind the frame portion  21  and performs rotational motion in a state of being grounded on the ground surface so that the frame portion  21  loaded with the cargo may move to a predetermined position. 
     Here, the pair of wheels  283  may be formed as a motor-integrated structure capable of generating power by itself to perform rotational motion. 
     More specifically, the pair of wheels  283  may include a wheel motor  2831  which is coupled to and supported to the support panels  282  and generates a rotational force, and a wheel body  2832  which is rotatably coupled to the wheel motor  2831  and performs rotational motion through the rotational force transmitted from the wheel motor  2831 . For example, the wheel motor  2831  is connected to a battery  216  to receive power, and is electrically connected to the controller  26  and the control portion  27  to control a rotational direction, a rotational speed, and the like through the operation of the control portion  27 . 
     Therefore, the hand lift device  2  can be moved to front, rear, left, right, upper and lower sides through the cargo loading unit  1  and the moving support portion  28 , so that the loaded cargo may be stably carried and unloaded to various positions. 
     The pair of forks  284  may be coupled to the support panel  282  and disposed in front of the frame portion  21  and may have a caster  285  at the end to switch the movement direction of the frame portion  21 . 
     Therefore, when the height of the cargo loaded on the hand lift device  2  is large, the operator may load the cargo directly onto the forks  284  by separating the cargo loading unit  1  from the frame portion  21 , and may also easily switch the movement position in a desired direction through the caster  285  when the hand lift device  2  is moved. For example, the caster  285  may be formed in the form of a wheel that is rotatably coupled to a pair of forks  284  on the ground and performs rotational motion along the ground. 
     Further, the pair of forks  284  can be positioned in the front and rear direction of the frame portion  21  along the surface of the support panel  282 . 
     Accordingly, the operator may adjust the length of the fork  284  according to the weight and the size of the cargo to be loaded, thereby stably distributing the load acting on the frame portion  21 . 
     For example, a plurality of fastening holes may be formed in a longitudinal direction of the support panel  282 , and fastening holes corresponding to at least one of the plurality of fastening holes may be formed in the pair of forks  284 . Accordingly, the pair of forks  284  may be disposed at a position corresponding to any of the plurality of fastening holes described above, and then fixed to the support panel  282  through a separate fastening means such as bolts and nuts. 
     Meanwhile, referring to  FIGS. 1 and 2 , the hand lift device  2  may further include a handle bar  215 . 
     The handle bar  215  is provided on the rear surface of the frame portion  21  and can adjust a position in the longitudinal direction of the frame portion  21  and can also adjust a height while being fixed to any one position of the frame portion  21 . 
     Accordingly, the operator can stably grip the handle bar  215  at various positions, and can also steer the hand lift device  2  using the handle bar  215  in a state in which the pair of wheels  283  is driven. 
     Further, although not illustrated in the drawings, the handle bar  215  may further include an auxiliary control means (not illustrated) capable of controlling the hand lift device  2 . Thus, the user may easily operate the hand lift device  2  while gripping the handle bar  215 . 
     Further, the hand lift device  2  may further include a fixing support portion  29 . 
       FIG. 6  is a side view illustrating a state in which the fixing support portion  29  is installed on the frame portion  21  of the hand lift device  2  according to the embodiment of the present invention. 
     Referring to  FIG. 6 , the fixing support portion  29  is detachably mounted on the frame portion  21 , and may be supported on the ground to support the frame portion  21  in a direction perpendicular to the ground. 
     The fixing support portion  29  may include a fixing panel  291  and a vertical support frame  292 . 
     The fixing panel  291  is formed in a flat plate and installed on the ground so as to support the vertical support frame  292  to be described below and distribute the load acting in the vertical direction from the vertical support frame  292  to the ground. 
     The vertical support frame  292  protrudes upward by a predetermined length in the vertical direction from the upper surface of the fixing panel  291  to form a slot  292   a  capable of accommodating a part of the frame portion  21  therein and support the outer surface of the frame portion  21  accommodated in the slot  292   a . Here, the vertical support frame  292  may be configured to simultaneously support both side surfaces and the rear surface of the frame portion  21  accommodated in the slot  292   a.    
     Further, the hand lift device  2  may further include a boarding portion  40 . 
       FIG. 7  is a side view schematically illustrating a state in which the boarding portion  40  is installed on the hand lift device  2 . 
     Referring to  FIG. 7 , the boarding portion  40  may be installed at a rear portion of the frame portion  21 , and may be formed in a boardable structure while the user is standing or sitting. 
     For example, the boarding portion  40  may be formed in a boardable foothold while the user is standing as illustrated in  FIG. 7A , and may be formed in a boardable chair while the user is sitting as illustrated in  FIG. 7B . In addition, in order to prevent the hand lift device  2  from tilting toward the rear side during boarding of the user, a separate caster (not illustrated) may be further provided at the lower side of the boarding portion  40  to be supported on the ground to distribute the load acting to the boarding portion  40  to the ground. However, the boarding portion  40  is not necessarily limited thereto, and may be modified and applied to various structures and forms. 
     As described above, since the hand lift device  2  can allow the operator to automatically load the cargo by the cargo loading unit  1  without manually loading the cargo, the hand lift device  2  can operate faster than manual operation, load more cargo over the same time, and operate with a small number of persons, thereby reducing the cost. 
     Hereinafter, a hand lift device  3  according to another embodiment of the present invention will be described. 
     For reference, each configuration for describing the hand lift device  3  according to another embodiment of the present invention uses the same reference numeral used for describing the hand lift device  2  for convenience of description, and the same or duplicated description will be omitted. 
       FIG. 8  is a perspective view illustrating a hand lift device  3  according to another embodiment of the present invention,  FIG. 9  is a side view schematically illustrating the hand lift device  3  according to another embodiment of the present invention, and  FIG. 10  is a side view schematically illustrating a driving method of the hand lift device  3  according to another embodiment of the present invention. 
     Referring to  FIGS. 8 and 9 , a hand lift device  3  according to another embodiment of the present invention includes a frame portion  31 , a chain  32  disposed in a longitudinal direction of the frame portion  31 , a cargo loading unit  1  configured to be connected to the chain  32  to load cargo, a power transmission portion  34  providing a driving force to the chain  32 , a sensor portion  35  sensing cargo loaded on the cargo loading unit  1 , and a controller  36  controlling driving of the power transmission portion  34  according to a sensing signal from the sensor portion  35 . 
     Referring to  FIG. 10 , the power transmission portion  34  includes an electric motor  341 , a rotational shaft  342  engaging with a driving shaft of the electric motor  341 , and a third sprocket  343  connected to the rotational shaft  342 . 
     The chain  32  may be sequentially gear-coupled to a first sprocket  312 , a third sprocket  343 , and a second sprocket  313 . Accordingly, when a driving force is generated from the electric motor  341 , the driving force is transmitted to the chain  32  through the third sprocket  343 . 
     The third sprocket  343  is disposed between the first sprocket  312  and the second sprocket  313  and disposed to deviate from a straight path formed by the first sprocket  312  and the second sprocket  313 . For example, the chain  32  connecting the first sprocket  312 , the third sprocket  343  and the second sprocket  313  is disposed in the shape of a “C” in the vicinity of the third sprocket  343 . 
     The power transmission portion  34  further includes a fourth sprocket  344  and a reinforcement chain  345 . 
     The fourth sprocket  344  is disposed to deviate from a straight path formed by the first sprocket  312  and the second sprocket  313 . Further, the fourth sprocket  344  is spaced apart from the third sprocket  343 . 
     At this time, the reinforcement chain  345  is installed to surround the third sprocket  343  and the fourth sprocket  344 , and is gear-coupled to the third sprocket  343  and the fourth sprocket  344 . The reinforcement chain  345  is disposed to face the chain  32  and the third sprocket  343  in different directions and the chain  32  and the reinforcement chain  345  rotate forward and backward by the driving force of the electric motor  341  transmitted through the third sprocket  343 . 
     The fourth sprocket  344  and the reinforcement chain  345  may complement the driving stability while the chain  32  receives the driving force by the third sprocket  343 . Specifically, the third sprocket  343  serves as a shaft, and the fourth sprocket  344 , which is a separate shaft, is added to the power transmission portion  34  in which the chain  32  rotates, thereby preventing the chain  32  from sliding in a direction opposite to the rotation direction from the third sprocket  343 . 
     Meanwhile, the power transmission portion  34  may further include a fifth sprocket  346  and a sixth sprocket  347 . 
     The fifth sprocket  346  may be disposed at an arbitrary point between the first sprocket  312  and the third sprocket  343  and the sixth sprocket  347  may be disposed at an arbitrary point between the third sprocket  343  and the second sprocket  313 . At this time, the fifth sprocket  346  and the sixth sprocket  347  may press the chain  32  in the direction in which the chain  32  surrounds the third sprocket  343 . 
     The fifth sprocket  346  and the sixth sprocket  347  provide a path through which the chain  32  moves and may add additional tension to the chain  32  to prevent the chain  32  from loosening. That is, the fifth sprocket  346  and the sixth sprocket  347  function to hold the tension of the chain  32  at a predetermined level or more. 
     Meanwhile, although not illustrated in the drawing, the hand lift device  3  according to another embodiment of the present invention may further include a chain tensioner (not illustrated) separately provided. The chain tensioner may compensate the sagging of the chain  32  by using self-elasticity. 
     The chain tensioner may be, for example, in the form of a spring member or a structure capable of generating an elastic force of which both ends are connected to the fifth sprocket  346  and the sixth sprocket  347 . The spring member may press the chain  32  using the self-elastic force generated between the fifth sprocket  346  and the sixth sprocket  347 . 
     Hereinafter, various embodiments of a cargo loading unit  1  applied to a hand lift device  3  will be described. 
     For reference, each configuration for describing the cargo loading unit  1  applied to the hand lift device  3  uses the same reference numerals used for describing the hand lift device  2  for convenience of description, and the same or duplicated description will be omitted. 
       FIG. 11  is a perspective view illustrating a part of the hand lift device according to another embodiment to which a cargo loading unit is applied. 
     Referring to  FIG. 11 , the cargo loading unit  1  may include an extension portion  11  and a hook portion  12  positioned at the end of the extension portion  11 . 
     That is, the cargo loading unit  1  may be formed in such a manner that a part of the cargo is hooked on the hook portion  12  to lift the cargo. 
     In addition, the cargo loading unit  1  may be formed in a shape capable of supporting the edge of the cargo through a plurality of rotatable blades. 
       FIG. 12  is a perspective view illustrating a hand lift device according to yet another embodiment to which a cargo loading unit is applied and  FIG. 13  is a perspective view illustrating the cargo loading unit illustrated in  FIG. 12 . 
     Referring to  FIGS. 12 and 13 , the cargo loading unit  1  may include a support frame  11 . 
     The support frame  11  may be mounted on the hand lift device  2  and can be lifted up and down through the hand lift device  2  and may be formed in the form of a plurality of structures. 
     More specifically, the support frame  11  may include a vertical member  111  provided on the hand lift device  2 , a horizontal member  112  which is horizontally arranged on the lower side of the vertical member  111  and connected to a support arm  12  to be described below to support the support arm  12 , and a reinforcement member  113  for connecting the vertical member  111  and the horizontal member  112 . 
     Further, the cargo loading unit  1  may include the support arm  12 . 
     The support arm  12  protrudes from the end of the support frame  11  in a predetermined length toward the forward direction of the hand lift device  2  and may form an accommodation space capable of accommodating the cargo therein. The support arms  12  may be disposed opposite to each other in the longitudinal direction of the support frame  11 , that is, the longitudinal direction of the horizontal member  112 . 
     More specifically, the support arm  12  may include a first arm  12   a  disposed on one side of the horizontal member  112  in the longitudinal direction of the horizontal member  112 , and a second arm  12   b  disposed on the other side of the horizontal member  112  in the longitudinal direction of the horizontal member  112 . 
       FIG. 14  is a cross-sectional view schematically illustrating a state in which a first blade is installed on a first arm of the cargo loading unit according to yet another embodiment. 
     Referring to  FIG. 14A , the first arm  12   a  and the second arm  12   b  may have a hollow tubular structure. A support structure  121  may be formed on the upper surfaces of the first arm  12   a  and the second arm  12   b  to have a shaft portion  131  and an elastic member  133  of a gripping blade  13  to be described below. For example, the support structure  121  is formed in a tunnel structure penetrating the inside thereof and may be formed on the middle or end portion in a width direction (X-axis direction) of each of the arms  12   a  and  12   b  on the upper surface of each of the arms  12   a  and  12   b . Here, referring to  FIG. 14B , when the support structure  121  is formed on the end portion of each of the arms  12   a  and  12   b , a support piece  127  supporting the lower surface of the gripping blade  13  may be further included on the side surface of each of the arms  12   a  and  12   b  opposed to each other. 
     Further, the first arm  12   a  and the second arm  12   b  are coupled to the horizontal member  112  in a detachable structure and can relatively move in the longitudinal direction of the horizontal member  112 . 
       FIG. 15  is a plan view schematically illustrating a state in which the first arm and the second arm are installed on the horizontal member of the cargo loading unit according to yet another embodiment. 
     Referring to  FIGS. 14 and 15 , the first arm  12   a  and the second arm  12   b  may include a first structure  122  and a second structure  123 . 
     The first structure  122  is disposed on the outer side of the horizontal member  112  and is exposed in the outer space and may have a support structure  121  on one side of which the gripping blade  13  and the elastic member  133  are installed. 
     The second structure  123  is inserted into the first structure  122  to support the load of the first structure  122  and a part of the second structure  123  is accommodated in the inner space of the horizontal member  112 , and when a driving device  125  of the first arm  12   a  and the second arm  12   b  is driven, the second structure  123  can be moved along a guide groove  112   a . For example, the length of a part of the second structure  123  that is inserted into the first structure  122  corresponds to the entire length of the first structure  122 , or may be formed in a half of the entire length of the first structure  122 . 
     On each end of the first arm  12   a  and the second arm  12   b , a plurality of pinion gears  124  which is opposite to the upper and lower sides of a rack gear  112   b  to generate a rotational force and movable along the rack gear  112   b  and a driving device  125  transmitting the rotational force to the plurality of pinion gears  124  may be provided. For example, the driving device  125  of the first arm  12   a  and the driving device  125  of the second arm  12   b  may be simultaneously controlled, and generate rotational forces in different directions during driving to enable the relative movement of the first arm  12   a  and the second arm  12   b . However, the driving device  125  is not necessarily limited thereto, and may be modified and applied in various forms within conditions that can realize the relative movement of the first arm  12   a  and the second arm  12   b.    
     Therefore, when a control command is transmitted to the driving device  125  of the first arm  12   a  and the driving device  125  of the second arm  12   b , the respective driving devices  125  are rotated in different directions and move along the rack gear  112   b , and as a result, the first arm  12   a  and the second arm  12   b  perform relative movement to adjust the size of the accommodation space. 
     Here, the horizontal member  112  is formed in a hollow tubular structure, and parts of the first arm  12   a  and the second arm  12   b  may be accommodated therein, and one side of the horizontal member  112  may have a guide groove  112   a  which is in contact with the outer surfaces of the first arm  12   a  and the second arm  12   b  in a longitudinal direction to guide the movement of the first arm  12   a  and the second arm  12   b . At the inner side of the horizontal member  112 , a rack gear  112   b  which is gear-engaged with a pinion gear  124  provided on each of the first arm  12   a  and the second arm  12   b  to guide the movement of the pinion gear  124  may be provided. 
       FIG. 16  is a view schematically illustrating a state in which the first blade is installed on the first arm by a grip space adjusting unit in the cargo loading unit according to yet another embodiment. 
     Referring to  FIG. 16 , the support arms  12  are installed on the first arm  12   a  and the second arm  12   b  to support a first blade  13   a  and a second blade  13   b  to be described below, respectively, and may further include a plurality of grip space adjusting units  126  for relatively moving the first blade  13   a  and the second blade  13   b  to adjust a distance between the first blade  13   a  and the second blade  13   b.    
     The grip space adjusting unit  126  may include a guide rail  126   a  provided on the upper surface of the support arm  12  and a transport block  126   b  provided on the guide rail  126   a  and movable along the guide rail  126   a . In addition, the grip space adjusting unit  126  may include a support bracket  126   c  provided on the transport block  126   b  and rotatably supporting the gripping blade  13 . Here, at the center of the upper side of the support bracket  126   c , a support structure  121  to which the shaft portion  131  of the gripper blade  13  is rotatably coupled is formed, and the gripping blade  13  which is rotatably coupled to the support structure  121  may be supported on the surface of the support bracket  126   c  and disposed horizontally when the cargo is unloaded. The gripping space adjusting unit  126  may include a driving device  126   d  which is provided on the upper surface of the support arm  12  and coupled to the support bracket  126   c  to move the support bracket  126   c . For example, the driving device  126   d  may be applied to a linearly movable hydraulic device or the like, but is not limited thereto, and may be modified and applied in various forms. 
     Further, the cargo loading unit  1  may include the gripping blade  13 . 
     Referring to  FIGS. 13 and 14 , the gripping blade  13  may be rotatably installed on the support arm  12  to be disposed horizontally in the accommodation space. 
     More specifically, the gripping blade  13  may be supported on the surface of each of the arms  12   a  and  12   b  when the cargo is unloaded to be horizontally disposed in the accommodation space, or supported on the surface of the support piece  127  provided on the side surface of each of the arms  12   a  and  12   b  to be horizontally disposed in the accommodation space. 
     Here, the gripping blade  13  may include a first blade  13   a  rotatably installed on the first arm  12   a  and a second blade  13   b  rotatably installed on the second arm  12   b.    
       FIG. 17  is a plan view schematically illustrating a state in which cargo is unloaded on the cargo loading unit according to yet another embodiment of the present invention and  FIG. 18  is a view schematically illustrating a process in which cargo is loaded on the cargo loading unit according to yet another embodiment of the present invention. 
     Referring to  FIG. 17 , when the cargo is unloaded, a distance D between the first blade  12   a  and the second blade  12   b  may be smaller than a distance D′ between the first blade  12   a  and the outer surface of the cargo supported by the second blade  12   b.    
     Referring to  FIGS. 13 and 14 , the gripping blade  13  may include a shaft portion  131 , a blade body  132 , and an elastic member  133 . 
     The shaft portion  131  is rotatably coupled to the support structure  121  formed on the upper surface of the support arm  12  and may be formed in the longitudinal direction at one end of the blade body  132 . 
     The blade body  132  extends from the shaft portion  131  to one side to be disposed in the accommodation space and may be rotated clockwise or counterclockwise together with the shaft portion  131  when the shaft portion  131  is rotated. In addition, a plurality of inclined guide surfaces  132   a  may be formed on one side and the other side of the blade body  132  in the longitudinal direction to guide the movement of the cargo when the cargo is loaded. For example, the plurality of inclined guide surfaces  132   a  is formed in a structure in which the width of the cross section is gradually narrowed in a direction in which the cargo enters the accommodation space when the cargo is loaded, so that the cargo is not caught by the outer surface of the cargo when the cargo is loaded to be guided to the accommodation space. 
     The elastic member  133  is provided around the shaft portion  131  to elastically support the blade body  132 . Further, the elastic member  133  may restrict a rotational angle of the gripping blade  13 . Here, the gripping blade  13  supported by the elastic member  133  may be rotated at an angle between 0° and 90°. For example, the elastic member  133  may act as a return spring which includes a first support wire member supported by the support arm  12 , a second support wire member supporting the blade body  132 , and a coil-shaped body provided around the shaft portion  131  to connect the first support wire member and the second support wire member. 
     Accordingly, as illustrated in  FIG. 18 , the gripping blade  13  rotates at a predetermined angle when the cargo is loaded to be separated outwardly, and then retracts inward by an elastic force to support the outer surface of the cargo. 
     More specifically, the first blade  13   a  and the second blade  13   b , which are horizontally disposed on the surfaces of the arms  12   a  and  12   b , slid along the outer surface of the cargo through the forward movement of the hand lift device  2 , and simultaneously are pressed against the outer surface of the cargo to be separated outwardly. The first blade  13   a  and the second blade  13   b  that are separated outwardly are supported on the outer surface of the cargo to maintain in the outwardly separated state and then retracts inward by an elastic force of the elastic member  133  to support the outer surface of the cargo when the cargo reaches a central point between the first blade  13   a  and the second blade  13   b  When reaching the center point. 
     On the other hand, when the cargo loading unit  1  is lifted up by the hand lift device  2 , the gripping blade  13  lifts up the cargo by supporting a stepped portion A 1  provided on the upper edge of the cargo. At this time, the load acting on the cargo in a vertical direction is added to the gripping blade  13  that supports the stepped portion A 1  of the cargo. Accordingly, the gripping blade  13  further retracts inwardly toward the outer surface of the cargo due to the load acting on the cargo in the vertical direction when the cargo is lifted up, and as a result, a support force acting on the cargo is strengthened to further stably fix the cargo. 
     For reference, the cargo loadable on the cargo loading unit  1  may be formed in a box form which is opened at the top and may accommodate the cargo therein. In addition, on the upper edge of the cargo, a bending portion A 2  which protrudes from the outer surface in a predetermined length to form the stepped portion A 1  may be formed. Here, a plurality of bending portions A 2  may be formed on the outer surface of the cargo to be spaced at predetermined intervals along the height of the cargo, and accommodating grooves A 3  which can accommodate a part of the gripping blade  13  may be formed among the plurality of bending portions A 2 . 
     Further, the gripping blade  13  may further include a guide roller  134 . 
       FIG. 19  is a view schematically illustrating a state in which the guide roller is installed on the blade body of the cargo loading unit according to yet another embodiment of the present invention. 
     Referring to  FIG. 19 , the guide roller  134  is installed at the end of the blade body  132 , and may perform the rotational motion while being in contact with the outer surface of the cargo when the cargo is loaded. 
     In addition, the hand lift device  2  may further include a plurality of angle adjusting means (not illustrated) which are installed inside the support arm  12  in the longitudinal direction of the support arm  12  and connected with the gripping blade  13  to rotate the gripping blade  13  at a predetermined angle during driving. 
     For example, the angle adjusting means may include a first gear portion which is installed on the shaft portion  131  of the gripping blade  13  to rotate the shaft portion  131 , a second gear portion which is installed inside the support arm  12  to be gear-engaged with the first gear portion and transmits a rotational force to the first gear portion, and a power portion which is installed inside the support arm  12  to be connected to the second gear portion and generates power according to a control command transmitted from the hand lift device  2  to transmit the rotational force to the second gear portion. 
     Therefore, the hand lift device  2  includes a gripping blade  13 , which is pressed against the outer surface of the cargo when the cargo is loaded on the cargo loading unit  1  and separated outwardly and then automatically retract inwardly by an elastic force to support the outer surface of the cargo, so that the operator can automatically load the cargo only by the operation of simply sliding the gripping blade  13  to the outer surface of the cargo through the movement of the hand lift device  2  without manually loading the cargo, thereby significantly shortening a cargo loading time and improving workability. 
     In addition, when the cargo loading unit  1  is lifted up through the hand lift device  2 , the load acting on the cargo in the vertical direction is added to the gripping blade  13  that supports the stepped portion of the cargo. Accordingly, the gripping blade  13  further retracts inwardly toward the outer surface of the cargo, thereby strengthening the supporting force acting on the cargo and more stably fixing the cargo. 
     In addition, when the cargo is loaded, the gripping blade  13  supports the bottom surface of the cargo and supports the circumferential surface of the cargo accommodated in the accommodation space without lifting up to lower the center of gravity of the loaded cargo, thereby more stably loading the cargo. 
     Further, the cargo loading unit  1  may be formed in a shape which can grip the outer surface of the cargo through a tongs-shaped gripping means. 
       FIG. 20  is a perspective view illustrating a hand lift device according to still another embodiment of the present invention to which a cargo loading unit is applied and  FIG. 21  is a plan view schematically illustrating the cargo loading unit illustrated in  FIG. 20 . 
     Referring to  FIGS. 20 and 21 , the cargo loading unit  1  may include a support portion  11 . 
     The support portion  11  may be formed in a plurality of structures that is installed on the hand lift device  2  to be lifted up and down and coupled to each other. 
     In addition, the support portion  11  may include a support member  111  having a driving portion  14  to be described below installed therein. 
     More specifically, the support member  111  may be formed in a structure having a ‘C’-shaped cross section to form an accommodation space for accommodating the gripping portion  13  and the driving portion  14  therein. In addition, a support structure may be further formed inside the support member  111  to stably fix the driving portion  14 . 
     Meanwhile, the end portion of the support member  111  facing the accommodation space may be formed to protrude forward by a predetermined length so as to support a part of the cargo when the cargo is placed in the accommodation space. 
     The support portion  11  may include a lifting member  112  installed on the hand lift device  2  to lift up and down and a coupling member  113  connecting the support member  111  and the lifting member  112 . For example, the lifting member  112  and the coupling member  113  may have protrusions and grooves corresponding to each other, and may be coupled by a male-female fitting method at the time of coupling. 
     Further, the cargo loading unit  1  may include the driving portion  14 . 
     The driving portion  14  is installed on the support portion  11  to be connected with the end portion of the gripping portion  13  accommodated in the support portion  11  and can be extended or contracted by performing linear motion in a horizontal direction. Accordingly, the driving portion  14  may push the gripping portion  13  connected to both ends outward or pull the gripping portion  13  inward to adjust the size of the accommodation space. 
     More specifically, the driving portion  14  is provided with a monodrum linear actuator that can be extended or contracted by performing the linear motion in the horizontal direction, so that both end portions may be connected to the respective support arms  13   a  and  13   b  of the gripping portion  13 . The driving unit  14  is extended or contracted by performing the linear motion in the horizontal direction so that the support arms  13   a  and  13   b  coupled to both ends thereof relatively move in the horizontal direction, thereby adjusting the size of the accommodating space formed inside the respective support arms  13   a  and  13   b  or gripping the outer surface of the cargo accommodated in the accommodation space. However, the driving portion  14  is not necessarily limited to the linear actuator, and may be modified and applied in various configurations within conditions capable of performing the same function. 
     Further, the cargo loading unit  1  may include the gripping portion  13 . 
     The gripping portion  13  is formed in a tongs shape to be rotatably coupled to both ends of the driving portion  14  and may form an accommodation space capable of accommodating the cargo therein. In addition, the gripping portion  13  may grip the cargo accommodated in the accommodation space by performing the relative motion in a horizontal direction when the driving portion  14  is driven. That is, the gripping portion  13  performs relative movement through the driving portion  14  to adjust the size of the accommodation space according to the size of the cargo to be loaded, then accommodates the cargo in the accommodation space, and presses the outer surface of the cargo accommodated in the accommodation space to grip the cargo. At this time, the gripping portion  13  gripping the cargo may be rotated at a predetermined angle around the coupling point with the driving portion  14  so as to correspond to the outer surface of the gripped cargo. 
     The gripping portion  13  may include a first support arm  13   a  which is rotatably installed on one side of the driving portion  14  and a second support arm  13   b  which is rotatably installed on the other side of the driving portion  14  and disposed opposite to the first support arm  13   a  to perform the relative movement with respect to the first support arm  13   a.    
     The first support arm  13   a  and the second support arm  13   b  may include a rotational shaft portion  131  which is rotatably installed on the end of the driving portion  14  and disposed in the inner space of the support portion  11 , and a gripping body  132  which is connected to the rotational shaft portion  131  to grip the cargo. 
     The gripping body  132  is coupled to the rotational shaft portion  131  so that one side may be disposed in the outer space of the support portion  11  and the other side may be disposed in the inner space of the support portion  11 . 
     In addition, the gripping body  132  may include a rotary blade  1321  and a gripping member  1322 . 
     The rotary blade  1321  may be coupled to the rotational shaft portion  131  to be rotatable together with the rotational shaft portion  131  and may be provided in plural in an axial direction of the rotational shaft portion  131 . 
     The gripping member  1322  is attached to the inner surface of the plurality of rotary blades  1321  and may be in close contact with the outer surface of the cargo to support the cargo when the cargo is loaded. 
     Here, the gripping member  1322  may be formed with a plurality of gripping surfaces. 
     More specifically, the gripping member  1322  is provided with a gripping surface S 1  which is formed in an arc shape facing the outside in the horizontal direction (X-axis direction) to support the outer surface of the cargo, and a separation prevention surface S 2  which is extended from the gripping surface S 1  and formed in an arc shape facing the inside in the horizontal direction (X-axis direction) to support the end portion of the cargo. In this case, a space between the plurality of gripping surfaces S 1  may be formed to be larger than the space between the plurality of separation prevention surface S 2 . However, the plurality of gripping surfaces formed on the gripping member  1322  is not necessarily limited thereto, but may be applied to the opposite case, or may be modified and applied into various shapes within conditions capable of performing the same function. 
     Meanwhile, a plurality of through holes may be formed in the gripping body  132  to reduce the weight of the gripping body  132 . On the one surface of the gripping member  1322  that is in contact with the cargo, a material having a large surface resistance may be coated or attached, or a protrusion and the like may be further formed so as to more stably grip the cargo when the cargo is loaded. 
     Further, the cargo loading unit  1  may further include a cushioning portion  15 . 
     The cushioning portions  15  are provided at both ends of the support portion  11  in the longitudinal direction of the support portion  11  and connected to the support arms  13   a  and  13   b  of the gripping portion  13 , respectively, to support the gripping portion  13  in the horizontal direction. For example, the cushioning portion  15  may be applied as a shock absorber including a cylinder filled with a cushioning agent such as gas, and a rod installed in the cylinder and linearly moving in the axial direction to transmit a load to the cushioning agent. However, the cushioning portion  15  is not necessarily limited thereto, and may be modified and applied in various configurations within conditions capable of performing the same function. 
     On the other hand, the cargo loading unit  1  may be formed in a different shape from the above. 
       FIG. 22  is a view schematically illustrating a modified example of the cargo loading unit according to still another embodiment of the present invention. 
     Referring to  FIGS. 20 and 22 , the cargo loading unit  1  may include a support portion  11 . 
     The support portion  11  may be formed in a plurality of structures that is installed on the hand lift device  2  to be lifted up and down and coupled to each other. 
     The support portion  11  may include a support member  111 . 
     The support member  111  is provided with a driving portion  14  to be described below therein and may be rotatably coupled with the gripping portion  13  to be described below. 
     More specifically, the support member  111  may be formed in a structure having a ‘C’-shaped cross section to form an accommodation space for accommodating the gripping portion  13  and the driving portion  14  therein. In addition, in the support member  111 , a plurality of coupling holes to which the gripping portion  13  is rotatably coupled may be formed. 
     The support portion  11  may include a lifting member  112  installed on the hand lift device  2  to lift up and down and a coupling member  113  connecting the support member  111  and the lifting member  112 . For example, the lifting member  112  and the coupling member  113  may have protrusions and grooves corresponding to each other, and may be coupled by a male-female fitting method at the time of coupling. 
     Further, the cargo loading unit  1  may include the gripping portion  13 . 
     The gripping portion  13  is formed in a tongs shape to be rotatably installed on the support portion  11  and may form an accommodation space capable of accommodating the cargo therein. In addition, the gripping portion  13  is connected with the driving portion  14  to be described below and is separated by rotating outward or retracted by rotating inward according to the driving of the driving portion  14 . Accordingly, the gripping portion  13  adjusts the size of the accommodation space according to the size and appearance of the cargo to be loaded and then accommodates the cargo in the accommodation space, and presses the outer surface of the cargo accommodated in the accommodation space to grip the cargo. 
     In addition, the gripping portion  13  may include a first support arm  13   a  which is rotatably installed on one side of the support portion  11  and a second support arm  13   b  which is rotatably installed on the other side of the support portion  11  and disposed opposite to the first support arm  13   a.    
     The first support arm  13   a  and the second support arm  13   b  perform relative motion through the driving portion  14  to be described below and may be rotated at a predetermined angle. For example, the first support arm  13   a  and the second support arm  13   b  may be rotated at angles between 0° and 180°. 
     Each of the first support arm  13   a  and the second support arm  13   b  may include a rotational shaft portion  131  which is rotatably installed on support portion  11  and disposed in the inner space of the support portion  11 , and a gripping body  132  which is connected to the rotational shaft portion  131  to grip the cargo. 
     The gripping body  132  is coupled to the rotational shaft portion  131  so that one side may be disposed in the outer space of the support portion  11  and the other side may be disposed in the inner space of the support portion  11  to be coupled to the driving portion  14 . Accordingly, the gripping body  132  may be rotated together with the rotational shaft portion  131  according to the driving of the driving unit  14  to be separated outward or retracted inward to grip the outer surface of the cargo. 
     In addition, the gripping body  132  may include a rotary blade  1321  and a gripping member  1322 . 
     The rotary blade  1321  may be coupled to the rotational shaft portion  131  to be rotatable together with the rotational shaft portion  131  and a plurality of rotary blades may be provided in an axial direction of the rotational shaft portion  131  and some thereof are accommodated into the support portion  11  to be coupled to the angle adjusting portion  14 . Here, one end of the driving portion  14  is coupled to a part of the rotary blade  1321  accommodated in the support portion  11 , and a slot through which one end of the driving portion  14  is movable during the driving of the driving portion  14  may be formed. However, the rotary blade  1321  is not necessarily coupled to the driving portion  14  through its structure, and may be connected to the driving portion  14  through various structures within the conditions capable of performing the same function. 
     The gripping member  1322  is attached to the inner surface of the plurality of rotary blades  1321  and may be in close contact with the outer surface of the cargo when the cargo is loaded to support the cargo. 
     Here, the gripping member  1322  may be formed with a plurality of gripping surfaces. 
     More specifically, the gripping member  1322  is provided with a gripping surface S 1  which is formed in an arc shape facing the outside in the horizontal direction (X-axis direction) to support the outer surface of the cargo, and a separation prevention surface S 2  which is extended from the gripping surface S 1  and formed in an arc shape facing the inside in the horizontal direction (X-axis direction) to support the end portion of the cargo. In this case, a space between the plurality of gripping surfaces S 1  may be formed to be larger than the space between the plurality of separation prevention surface S 2 . However, the plurality of gripping surfaces formed on the gripping member  1322  is not necessarily limited thereto, but may be applied to the opposite case, or may be modified and applied into various shapes within conditions capable of performing the same function. 
     Meanwhile, a plurality of through holes may be formed in the gripping body  132  to reduce the weight of the gripping body  132 . On the one surface of the gripping member  1322  that is in contact with the cargo, a material having a large surface resistance may be coated or attached, or a protrusion and the like may be further formed so as to more stably grip the cargo when the cargo is loaded. 
     Further, the cargo loading unit  1  may include the driving portion  14 . 
     The driving portion  14  is installed on the support portion  11  to be connected with the end portion of the gripping portion  13  accommodated in the support portion  11  and pushes outwardly or pulls inwardly the end portion of the gripping portion  13  by performing the linear motion to adjust a rotational angle of the gripping portion  13 . 
     More specifically, the driving portion  14  may be applied as a linear actuator which is connected to both the support arms  13   a  and  13   b  of the gripping portion  13  to pull inwardly or push outwardly the end portions of both the support arms  13   a  and  13   b  of the gripping portion  13  through the linear motion. For example, the linear actuator includes a linear motor installed in the center of the inside of the support portion  11 , and a linear shaft which is installed in the linear motor, extended or contracted in both directions of the linear motor in the X-axis direction when the linear motor is driven to perform the linear motion, and coupled to both the support arms  13   a  and  13   b  of the gripping portion  13 . However, the linear actuator is not necessarily limited thereto, and may be modified and applied in various configurations within conditions capable of performing the same function. 
       FIG. 23  is a view schematically illustrating another modified example of the cargo loading unit according to still another embodiment of the present invention and  FIG. 24  is a view schematically illustrating a first angle adjusting unit of the cargo loading unit of  FIG. 23 . 
     Referring to  FIGS. 20 and 23 , the cargo loading unit  1  may include a support portion  11 . 
     The support portion  11  may be formed in a plurality of structures that is installed on the hand lift device  2  to be lifted up and down and coupled to each other. 
     In addition, the support portion  11  may include a support member  111  which is axially coupled to a rotation portion  12  to be described below and rotatably supports the rotation portion  12 . 
     The support member  111  may include a panel portion  111   a , a shaft portion  111   b , and a bearing portion  111   c.    
     The panel portion  111   a  may be installed on the coupling member  113  and formed in a plate-like structure having a predetermined thickness. For example, the panel portion  111   a  may be formed with an upper-lower symmetrical structure in which the width of the cross section is gradually decreased toward the central portion in the vertical direction. However, the panel portion  111   a  is not limited thereto, and may be modified and applied into various shapes. 
     The shaft portion  111   b  may protrude from the central portion of the panel portion  111   a  by a predetermined length. For example, the shaft portion  111   b  may be integrally formed with the panel portion  111   a  or may be coupled to the panel portion  111   a  through a fastening means. 
     The bearing portion  111   c  is provided around the shaft portion  111   b  to support the rotation portion  12  to be described below and may distribute the axial load applied from the rotation portion  12  when the rotation portion  12  is rotated. For example, the bearing portion  111   c  may include an outer shell and an inner shell, a ball that performs rolling motion between the outer shell and the inner shell, and a cage that supports the ball. 
     The support portion  11  may include a lifting member  112  installed on the hand lift device  2  to lift up and down and a coupling member  113  connecting the support member  111  and the lifting member  112 . For example, the lifting member  112  and the coupling member  113  may have protrusions and grooves corresponding to each other, and may be coupled by a male-female fitting method at the time of coupling. 
     Further, the cargo loading unit  1  may include the rotation portion  12 . 
     The rotation portion  12  is installed on the support portion  11  and can be rotated clockwise or counterclockwise through the driving of the driving portion  14  to be described below or can also be rotated at a predetermined angle. 
     The rotation portion  12  may include a bracket  121 , a driven gear  122 , a gear fixing member  123 , and a diaphragm  124 . 
     The bracket  121  is formed in a structure having a ‘C’ shaped cross section to form an accommodation space for accommodating the gripping portion  13  to be described below and the first angle adjusting unit  141  of the driving portion  14 . The bracket  121  is coupled to the shaft portion  111   b  of the support member  111  and connected to the driven gear  122  to be described below and can be rotated clockwise or counterclockwise on one side of the panel portion  111   a  at the time of driving a second driving portion  142  transmitting the rotational force to the driven gear  122 . For example, the bracket  121  can be rotated at an angle of 0° to 360° together with the driven gear  122 , and the bracket  121  may be formed with a plurality of coupling holes to which the gripping portion  13  to be described below can be coupled. 
     Meanwhile, the end portion of the bracket  121  facing the accommodation space may be formed to protrude forward by a predetermined length so as to support a part of the cargo when the cargo is placed in the accommodation space. 
     In addition, the bracket  121  may be formed in a structure that is extendable in the longitudinal direction (X-axis direction). 
     More specifically, the bracket  121  has an outer portion (not illustrated) which forms an outer shape and is rotatably provided on the bearing portion  111   c  with a driven gear  122  to be described below at one side, and an inner portion (not illustrated) which is installed inside the outer portion and linearly movable in the longitudinal direction (X-axis direction) along the inner surface of the outer portion. Here, the gripping portion  13  and the driving portion  14  to be described below are provided in the inner portion, and a power transmission means (not illustrated) provided in the outer portion to linearly move the inner portion may be provided between the outer portion and the inner portion. 
     Accordingly, the bracket  121  may be extended or contracted by a predetermined length in the longitudinal direction (X-axis direction) according to the transmitted control command to variably adjust the size of the accommodation space formed inside the gripping portion  13 , thereby loading the cargos having more various sizes. 
     The driven gear  122  is disposed between the bracket  121  and the panel portion  111   a  and installed around the bearing portion  111   c  and may be rotated together with the bracket  121  when receiving the rotational force. For example, the driven gear  122  may be rotated by receiving a rotational force from the second angle adjusting unit  142  of the driving portion  14  to be described below and may be fixed to one surface of the bracket  121  through the gear fixing member  123  to be described below. 
     The gear fixing member  123  protrudes outward from the outer surface of the bracket  121  to be coupled to the driven gear  122 , thereby fixing the driven gear  122  to the outer surface of the bracket  121 . For example, the gear fixing member  123  is formed in a tubular structure in which a stepped portion is formed in the periphery and a bearing portion  111   c  is accommodated in the inner side and coupled to the inner surface of the driven gear  122  to support the driven gear  122  while being fixed to the outer surface of the bracket  121 , thereby preventing the driven gear  122  from being separated. However, the gear fixing member  123  is not necessarily limited to the shape thereof, and may be modified and applied in various configurations within conditions capable of performing the same function. 
     The diaphragm  124  may be disposed at an inner central portion of the bracket  121  and protrude from the inner surface of the bracket  121  by a predetermined length. Through this, the diaphragm  124  may not only divide the internal space of the bracket  121  into a plurality of spaces but also reinforce the rigidity of the bracket  121  by supporting the inner central portion of the bracket  121  formed in a ‘C’ shape. 
     Further, the cargo loading unit  1  may include the gripping portion  13 . 
     The gripping portion  13  is formed in a tongs shape to be rotatably installed on the rotation portion  12  and may form an accommodation space capable of accommodating the cargo therein. In addition, the gripping portion  13  is connected with the driving portion  14  to be described below and is separated by rotating outward or retracted by rotating inward by a rotational force received from the driving portion  14 . Accordingly, the gripping portion  13  adjusts the size of the accommodation space according to the size and appearance of the cargo to be loaded and then accommodates the cargo in the accommodation space, and presses the outer surface of the cargo accommodated in the accommodation space to support the cargo. 
     In addition, the gripping portion  13  may include a first support arm  13   a  which is rotatably installed on one side of the bracket  121  and a second support arm  13   b  which is rotatably installed on the other side of the bracket  121  and disposed opposite to the first support arm  13   a.    
     The first support arm  13   a  and the second support arm  13   b  perform relative motion through the driving portion  14  to be described below and may be rotated at a predetermined angle. For example, the first support arm  13   a  and the second support arm  13   b  may be rotated at angles between 0° and 180°. 
     Each of the first support arm  13   a  and the second support arm  13   b  may include a rotational shaft portion  131  which is rotatably installed on bracket  121  and disposed in the inner space of the bracket  121 , and a gripping body  132  which is connected to the rotational shaft portion  131  to grip the cargo. 
     The gripping body  132  is coupled with the rotational shaft portion  131  and disposed in the outer space of the bracket  121  and may be separated outwardly or retracted inwardly by rotating together with the rotational shaft portion  131  according to the driving of the first angle adjusting unit  141  to grip the outer surface of the cargo. 
     In addition, the gripping body  132  may include a rotary blade  1321  and a gripping member  1322 . 
     A plurality of rotary blades  1321  may be provided in an axial direction of the rotational shaft portion  131  and integrally coupled to the rotational shaft portion  131  to rotate together with the rotational shaft portion  131  clockwise or counterclockwise when the driving portion  14  is driven. 
     The gripping member  1322  is attached to the inner surface of the plurality of rotary blades  1321  and may be in close contact with the outer surface of the cargo when the cargo is loaded to support the cargo. 
     Here, the gripping member  1322  may be formed with a plurality of gripping surfaces. 
     More specifically, the gripping member  1322  is provided with a gripping surface S 1  which is formed in an arc shape facing the outside in the horizontal direction (X-axis direction) to support the outer surface of the cargo, and a separation prevention surface S 2  which is extended from the gripping surface S 1  and formed in an arc shape facing the inside in the horizontal direction (X-axis direction) to support the end portion of the cargo. In this case, a space between the plurality of gripping surfaces S 1  may be formed to be larger than the space between the plurality of separation prevention surface S 2 . However, the plurality of gripping surfaces formed on the gripping member  1322  is not necessarily limited thereto, but may be applied to the opposite case, or may be modified and applied into various shapes within conditions capable of performing the same function. 
     Meanwhile, a plurality of through holes may be formed in the gripping body  132  to reduce the weight of the gripping body  132 . On the one surface of the gripping member  1322  that is in contact with the cargo, a material having a large surface resistance may be coated or attached, or a protrusion and the like may be further formed so as to more stably grip the cargo when the cargo is loaded. 
     Further, the gripping body  132  may be formed in a multi joint structure. 
     More specifically, the gripping body  132  may include a plurality of joint bodies, a link member connecting the plurality of joint bodies to each other, and a power means which is installed on the plurality of joint bodies to adjust the size between the plurality of joint bodies through the control command. 
     Accordingly, the gripping body  132  may perform joint motion to load cargo having various sizes and shapes, and further stably grip the outer surface of the cargo. 
     Further, a plurality of gripping bodies  132  are provided inside the bracket  121 , and may be individually driven in a vertical direction (Z-axis direction). 
     Accordingly, the plurality of gripping bodies  132  may stably grip cargo having a non-uniform outer shape at a plurality of positions through separate driving. 
     Further, the cargo loading unit  1  may include the driving portion  14 . 
     The driving portion  14  may be installed on the support portion  11  and the rotation portion  12  and transmit the rotational force to the rotation portion  12  and the gripping portion  13  to adjust the rotational angle of the rotation portion  12  and the gripping portion  13 . 
     Referring to  FIGS. 23 and 24 , the driving portion  14  may include a first angle adjusting unit  141  and a second angle adjusting unit  142 . 
     The first angle adjusting unit  141  includes a first arm controller  141   a  which is installed inside the bracket  121  to rotate the first support arm  13   a  and a second arm controller  141   b  which is provided inside the bracket  121  and disposed opposite to the first arm controller  141   a  to rotate the second support arm  13   b.    
     Here, the first arm controller  141   a  and the second arm controller  141   b  may include a first power transmission gear  1411 , a second power transmission gear  1412 , and a first driving device  1413 . 
     The first power transmission gear  1411  may be installed around the rotational shaft portion  131  and rotatable together with the rotational shaft portion  131 . 
     The second power transmission gear  1412  is rotatably provided on the inside of the bracket  121  and gear-engaged with the first power transmission gear  1411  and a third power transmission gear  1413   b  to be described below, and transmits a rotational force to the first power transmission gear  1411  while rotating at the time of driving the first driving device  1413  to rotate the first power transmission gear  1411 . 
     The first driving device  1413  is installed inside the bracket  121  and connected to the second power transmission gear  1412  and may perform linear motion to rotate the second power transmission gear  1412  clockwise or counterclockwise. 
     Here, the first driving device  1413  may include a linear actuator  1413   a  and a third power transmission gear  1413   b.    
     The linear actuator  1413   a  is installed inside the bracket  121  and can perform linear motion in the longitudinal direction of the bracket  121 . For example, the linear actuator  1413   a  includes a linear motor, a linear shaft which is provided on the linear motor to be rotated and has a spiral groove formed on the outer surface thereof, and a transport block which is installed on the linear shaft, linearly moves upon rotation of the linear shaft, and has a third power transmission gear  1413   b  installed on one surface. However, the linear actuator  1413   a  is not necessarily limited thereto, and may be modified and applied in various configurations within conditions capable of performing the same function. 
     The third power transmission gear  1413   b  is installed on the linear actuator  1413   a  to be gear-engaged with the second power transmission gear  1412  and may linearly move to one side or the other side upon driving of the linear actuator  1413   a  to rotate the second power transmission gear  1412 . For example, the third power transmission gear  1413   b  may be applied as a rack gear. 
     The second angle adjusting unit  142  is installed on the support member  111  and may transmit the rotational force to the driven gear  122  to rotate the bracket  121 . 
     More specifically, the second angle adjusting unit  142  may include a second driving device  1421  which is installed and fixed on the support member  111 , and a drive gear  1422  which is connected to the second driving device  1421  and gear-engaged with the driven gear  122  and generates a rotational force when the second driving device  1421  is driven to rotate the driven gear  122 . 
     Therefore, the hand lift device  2  is provided with the gripping portion  13  having a tongs shape capable of gripping the cargo by adjusting the accommodation space through the relative movement of the cargo loading unit  1 , thereby easily gripping and loading the cargo having various sizes and shapes. 
     In addition, since the hand lift device  2  is provided with the rotation portion  12  which is rotatable clockwise or counterclockwise, the cargo can be gripped at various positions, thereby increasing the usability and efficiently loading various types of cargo. 
     Further, by controlling the gripping portion  13  through the driving portion  14  to which the linear actuator is applied, the pressing force suitable for the cargo is finely adjusted according to the shape of the cargo, the material of the cargo or the hardness of the cargo so as to stably load the cargo. 
     In addition, when the cargo is loaded, the gripping portion  13  supports the bottom surface of the cargo and supports the circumferential surface of the cargo accommodated in the accommodation space without lifting up to lower the center of gravity of the loaded cargo, thereby more stably loading the cargo. 
     While the embodiments of the present invention have been illustrated and described above, the present invention is not limited to the aforementioned specific embodiments, various modifications may be made by a person with ordinary skill in the technical field to which the present invention pertains without departing from the subject matters of the present invention that are claimed in the claims, and these modifications should not be appreciated individually from the technical spirit or prospect of the present invention.