TECHNICAL FIELD

[0001] The present disclosure relates to hand tools. More particularly, the present disclosure relates to an energy-saving socket wrench and methods for operating the socket wrench. The socket wrench may be used to rapidly rotate fasteners such as bolts or nuts, thus, suitable for use during early stage of tightening or final stage of loosening. BACKGROUND

[0002] Socket wrenches are suitable for turning bolts or nuts that are only accessible from a small or narrow space or positioned in a deep recess. A socket wrench typically includes multiple sockets with a six-point opening or a twelve-point opening, a handle, a connecting rod and other accessories. Traditional socket wrenches are inconvenient to use because the socket wrench can only turn a nut or bolt for a certain angle after the socket is attached to the nut or bolt. The socket must be removed from the nut or bolt and re-attached to the nut or bolt in order to perform another turn. It usually takes multiple turns before the nut or bolt can be loosened or tightened. Such operation is not efficient because it takes a long time and consumes a large amount of energy.

[0003] Compared to traditional socket wrenches, two-direction socket wrenches are easier to use because two-direction wrenches can turn a nut or bolt when rotating the handle along both directions to tighten or loosen the nut or bolt. However, two-direction socket wrenches generally apply a large force on the nut or bolt and turn the nut or bolt slowly. Since a nut or bolt can be turned without a large force during an early stage of tightening or a final stage of loosening, the two-direction wrenches wastes time and energy, therefore, are also not efficient.

[0004] Therefore, there is a need for a socket wrench that is easy to use and/or efficient to use during an early stage of tightening or a final stage of loosening.

DISCLOSURE OF THE DISCLOSURE

[0005] One embodiment provides an energy saving socket wrench. The socket wrench includes a handle having a power input used to grip and tighten or loosen a fastener, and a power output to connect with the fastener to be tightened or loosened. The power output and the handle are fixedly connected without relative rotation during operation. The handle comprises an outer shell, and a speed increase assembly disposed inside the outer shell, wherein the speed increase assembly is connected to the power output.

[0006] Another embodiment provides an energy saving socket wrench including an outer shell, a power input, a rotating shaft disposed in the outer shell, wherein the rotating shaft has a first end and a second end, and the first end connected to the power input, and a self lock assembly coupled to the second end of the rotating shaft. The self lock assembly comprises a drive sub-assembly coupled the second end of the rotating shaft, and a driven sub-assembly. The socket wrench further includes a power output coupled the driven sub-assembly. An input force from the power input is transmitted to the power output, and a reaction force from the power output is not transmitted to the power input.

[0007] Another embodiment provides an energy saving socket wrench including an outer shell comprising a handle section, an electric drive mechanism disposed in the outer shell, a self lock assembly disposed in the outer shell. The self lock assembly comprises a drive sub-assembly, and a driven sub-assembly. The socket wrench further includes a speed reduce assembly disposed between the electric drive mechanism and the self lock assembly, and a power output coupled to the driven sub-assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.

[0009] Figure 1 is a schematic perspective view of a socket wrench according to one embodiment of the present disclosure.

[0010] Figure 2 is a schematic partial exploded view of the socket wrench of Figure 1 .

[0011] Figure 3 is a schematic sectional view of the socket wrench of Figure 1 . [0012] Figure 4 is a schematic perspective view of intermediate gears of the socket wrench of Figure 1 .

[0013] Figure 5 is a schematic perspective view of an electric socket wrench according to one embodiment of the present disclosure.

[0014] Figure 6 is a schematic exploded view of the electric socket wrench of Figure 5.

[0015] Figure 7 is a schematic sectional view of the electric socket wrench of Figure 5.

[0016] Figure 8 is a schematic perspective view of a worm and worm gear of the electric socket wrench of Figure 5.

[0017] Figure 9 is a schematic perspective view of an electric socket wrench according to one embodiment of the present disclosure.

[0018] Figure 10 is a schematic exploded view of the electric socket wrench of Figure 9.

[0019] Figure 1 1 is a schematic sectional view of the electric socket wrench of Figure 9.

[0020] Figures 12a -12c are schematic perspective views of the electric socket wrench of Figure 9 with a drive head at different angles.

[0021] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.

DETAILED DESCRIPTION

[0022] The present disclosure provides improvements to structure and operation methods of traditional socket wrenches to achieve rapid fastener turning and save energy. Socket wrenches according to embodiment of the present disclosure may be used to improve efficiency and save energy during an early stage of tightening or a final stage of loosening.

[0023] The socket wrench of the present disclosure includes a handle having a power input used to grip and tighten or loosen a fastener, and a power output to connect with the fastener to be tightened or loosened. The power output and the handle are fixedly connected without relative rotation during operation. The handle comprises an outer shell, and a speed increase assembly disposed inside the outer shell, wherein the speed increase assembly is connected to the power output.

[0024] Socket wrenches according to the present disclosure are described in detail with exemplary embodiments below. However, the present disclosure is not limited to the exemplary embodiments. Any change devised by persons skilled in the art falls within the scope of the protection of the present disclosure.

Embodiment 1

[0025] Figures 1 -3 schematically illustrate an energy-saving socket wrench according to one embodiment of the disclosure. The socket wrench may include an outer shell 1 . A rotating shaft and a self lock assembly are disposed in the outer shell 1 . A first end of the rotating shaft is coupled to a power input for receiving external force during operation. Alternatively, the power input and the rotating shaft may be formed in a unitary body. A second end of the rotating shaft is connected to the self lock assembly. The self lock assembly is configured to prevent the power output from rotating backwards. The self lock assembly includes a power output or a connection to couple with a power output end. The self lock assembly includes at least a drive sub-assembly and a driven sub-assembly. The drive sub-assembly is connected to the power input through the rotating shaft. The driven sub-assembly is connected to the power output or formed in a unitary body with the power output end. The drive sub-assembly drives and moves the driven sub-assembly while the driven sub-assembly cannot move the drive sub-assembly, thus, force from the power input may be transmitted to the power output while force from the power output cannot be transmitted to the power input.

[0026] In the embodiment of Figures 1 -3, the outer shell 1 may include two sections coupled together. For example, the outer shell 1 may include a chamber section 1 1 and a lid section 12 coupled to the chamber section 1 1 . The chamber section 1 1 may include a handle section 1 1 1 and a head section 1 12. The lid section 12 may include a handle section 121 and a head section 122. The handle sections 1 1 1 and 121 join together to form a handle. The head sections 1 12 and 122 join together to form a head. The handle and the head may be formed in a unitary body, fixedly coupled together, or removably connected with one another. In the embodiment of Figures 1 and 2, the chamber section 1 1 and the lid section 12 are coupled together by screws.

[0027] In the embodiment of Figures 1 -3, the drive sub-assembly includes a worm 2 and the driven sub-assembly includes a worm gear 3 meshing with the worm 2. The worm 2 may be fixedly or removably coupled to the rotating shaft. The worm gear 3 is coupled to the power output 31 . Alternatively, the worm gear 3 and the power output 31 may be formed in one piece. The power output 31 extends outside the outer shell 1 from the head. The worm gear 3 may be gears that are suitable to mesh with a worm and/or suitable to provide automatic lock against reverse rotation. In one embodiment, the worm gear 3 may be cylindrical a gear with slanted teeth for matching with the worm 2 and preventing reverse rotation. The power output 31 may be a shaft to securely connect with a socket. In one embodiment, the power output 31 may be a squared shaft. The power output 31 may connect with sockets to tighten or loosen fasteners. In one embodiment, sockets may encase over the power output 31 to receive power from the power output 31. Alternatively, the power output 31 may be formed in the form of a socket.

[0028] During operation, operator turns the power input 6 to rotate the worm 2, the worm 2 in turn drives the worm gear 3 to rotate, therefore, transferring the rotation from the power input 6 to rotation of the power output 31 to turn a bolt or nut. For example, rotation of the power input 6 may be transferred to a rapid rotation of the power output 31 to rapidly turning a bolt or nut during an early stage of tightening or a final stage of loosening.

[0029] During operation, as the power output 31 applies a force to a bolt or nut to turn the bolt or nut, the bolt or nut applies a relatively large reaction force to the power output 31 . The reaction force is then applied to the worm 2 through the worm gear 3 causing the worm gear 3 to lock with the worm 2 therefore preventing any reverse rotation of the worm 2 and the worm gear 3. This locking mechanism enables a smooth operation of tightening or loosening particularly when a relatively large rotational force is required to turn a bolt or nut and a relative large reaction force is generated during a final stage of tightening or an early stage of loosening.

[0030] The embodiment of Figures 1 -3 may further include a speed increase assembly attached to the rotating shaft. The speed increase assembly may be formed by ready to use speed increase gear assemblies. In one embodiment, the rotating shaft may include a first rotating shaft 4 and a second rotating shaft 5. A first end 41 of the first rotating shaft 4 is connected to the power input 6. As shown in Figure 2, the first end 41 includes a connection section 41 1 . The power input 6 includes a cylindrical body having a large outer diameter. The cylindrical body is encased over the connection section 41 1. The cylindrical body cannot rotate relatively to the connection section 41 1 . The ensure that the cylindrical body does not rotate relative to the connection section 41 1 , the connection section 41 1 may be a squared column and the cylindrical body may include a squared through hole or squared recess to receive the connection section 41 1 . Other than squared shape, interface between the connection section 41 1 and the power input 6 may be any suitable shape that can prevent slippage. In one embodiment, the interface between the connection section 41 1 and the power input 6 may be a circular and an adhesive may be applied between the connection section 41 1 and power input 6 to prevent relative rotation. Alternatively, the power input 6 may be unitarily formed with the first end 41 of the first rotating shaft 4.

[0031] A second end 42 of the first rotating shaft 4 is fixedly coupled to a first gear 7. The first gear 7 may encase the first rotating shaft 4 at the second end 42. Alternatively, the first gear 7 may be formed unitarily on the second end 42.

[0032] The second end 42 may have an inner receiving recess or an inner receiving hole 421 for encasing the second rotating shaft 5. A first end 51 of the second rotating shaft 5 may be inserted into the inner receiving recess or inner receiving hole 421 . A second end 52 of the second rotating shaft 5 may be a shaft of the worm 2. The worm 2 may be fixedly encased on the second end 52. A second gear 8 may be disposed on a middle section of the second rotating shaft 5 between the first end 51 and the second end 52. In one embodiment, the second gear 8 may be fixedly encased on the second rotating shaft 5. Alternatively, the second gear 8 and the second rotating shaft 5 may be formed in a unitary body.

[0033] A plurality of intermediate gears 9 may be coupled between the first gear 7 and the second gear 8. The plurality of intermediate gears 9 are positioned to mesh sequentially to form a transmission train between the first gear 7 and the second gear 8. The plurality of intermediate gears 9 may be coupled in series. In the embodiment of Figure 2, five intermediate gears 9 are coupled between the first gear 7 and the second gear 8. A position rod 10 may be used to position a portion of the plurality of intermediate gears 9. The position rod 10 may be fixed on an inner side of the outer shell 1 as shown in Figure 3. The plurality of intermediate gears 9 may be alternatively encased on the position rod 10 and the first end 51 of the second rotating shaft 5.

[0034] As shown in Figure 4, each of the plurality of intermediate gears 9 may include a large gear 91 and a small gear 92. The large gear 91 and the small gear 92 are coaxial but with different diameters. In one embodiment, the large gear 91 and the small gear 92 may be formed in a unitary body. The large gear 91 of each intermediate gear 9 meshes with the small gear 92 of the neighboring intermediate gear 9. Each pair of neighboring intermediate gears 9 are fixed on the position rod 10 and the first end 51 of the second rotating shaft 5 respectively. The small gear 92 of the intermediate gear 9 at a first end near the first rotating shaft 4 meshes the first gear 7 on the second end 42 of the first rotating shaft 4. The large gear 91 of the intermediate gear 9 at the opposite end meshes with the second gear 8 positioned between the first end 51 and the second end 52 of the rotating shaft 5. As shown in Figures 2 and 3, the large gear 91 of the upper most intermediate gear 9 on the position rod 10 meshes the second gear 8 which is positioned between the first end 51 and the second end 52 of the rotating shaft 5. The small gear 92 of the lower most intermediate gear 9 on the position rod 10 is coupled to the first gear 7 which is positioned on the second end 42 of the first rotating shaft 4. In the embodiment of Figures 1 -3, the first rotating shaft 4 is positioned inside the handle. The second rotating shaft 5, the position rod 10, the worm 2, and the worm gear 3 are positioned inside the head.

[0035] To use the socket wrench to tighten a fastener, such as a bolt or nut, attach a socket to the power output 31 , encase the socket around the fastener, then rotate the large diameter cylinder of the power input 6 clockwise to pre-tighten the fastener. When it becomes difficult to rotate the power input 6, the early stage of tightening or pre-tightening is complete. At this time, grip the handle of the outer shell 1 and turn the handle along a tightening direction to tighten the fastener. The fastener is therefore tightened with rapidly and easily. To use the socket wrench to loosen a fastener, such as a bolt or nut, attached a socket to the power output, encase the socket around the fastener, grip the handle of the outer shell 1 and turn the handle along a loosening direction to loosen the fastener. Once the fastener becomes loose, rotate the large diameter cylinder of the power input 6 counter clockwise, therefore completely loosen or remove the fastener. The above operation is only one example. The present disclosure is not limited to the above example. Socket wrench of the present disclosure may be configured to tighten a fastener by turning the power input 6 counter clockwise and to loosen a fastener by turning the power input 6 clockwise.

Embodiment 2

[0036] Figure 5 schematically illustrates an energy-saving electric socket wrench according to the present disclosure. The electric socket wrench includes an outer shell 1 . The outer shell 1 may include a handle section. The outer shell 1 includes two sections that may be assembled together. The outer shell 1 may include a recess body 1 1 ' and a lid 12' as shown in Figure 6. The recess body 1 1 ' includes a recess to accommodate components of the socket wrench. The recess body 1 1 ' and the lid 12' may be attached together to form the outer shell 1 . The outer shell 1 provides the handle section at a distal end from a power output of the socket wrench. An electric drive assembly, a self lock assembly, and a speed reduce assembly may be disposed inside the outer shell 1 . The speed reduce assembly may be disposed between the electric drive assembly and the self lock assembly. The self lock assembly includes a power output. Alternatively, the self lock assembly may be coupled to a power output. The self lock assembly includes at least a drive sub-assembly and a driven sub-assembly. The drive sub-assembly is connected to the electric drive assembly. The driven sub-assembly is connected to the power output. The drive sub-assembly drives and moves the driven sub-assembly while the driven sub-assembly cannot drive and move the drive sub-assembly.

[0037] In the present embodiment, the self lock assembly includes a power output 31 . To pre-tighten or further loosen a fastener, turn on the electric drive assembly so that the electric drive assembly drives the speed reduce assembly and the self lock assembly, thus transmitting power to the power output 31 . During a final stage of tightening or an early stage of loosening when a large force is needed to turn a fastener, turn off the electric drive assembly and use the socket wrench as a manual socket wrench. When the electric drive assembly is turn off, grip the handle and turn the socket wrench. The self lock assembly prevents the reactive force from the fastener to rotate the speed reduce assembly backwards, therefore facilitating operation of the socket wrench.

[0038] In the embodiment shown in Figures 6 and 7, the self lock assembly may include one drive sub-assembly and one drive sub-assembly. Alternatively, the self lock assembly may include multiple drive sub-assemblies and/or multiple driven sub-assemblies. In the embodiment of Figures 6 and 7, the drive sub-assembly includes a worm 2 and the driven sub-assembly includes the worm gear 3 coupled to the worm 2. The worm 2 may be fixedly or removably connected to the speed reduce assembly. In the present embodiment, the worm 2 is removably connected to the speed reduce assembly. The worm gear 3 is coupled to the power output 31. The worm gear 3 may be fixedly or removably coupled to the power output 31 . Alternatively, the worm gear 3 and the power output 31 may be formed in a unitary body. In the present embodiment, the worm gear 3 and the power output 31 are formed in one piece. The power output 31 may be a plug or a socket. In the present embodiment, the power output 31 is a square shaped plug.

[0039] When using the electric socket wrench during an early stage of tightening or a final stage of loosening, turn on the electric drive assembly to rotate the worm 2, the worm 2 then drives and rotates the worm gear 3 and transmitting the power to the power output 31 .

[0040] When using the electric socket wrench during a final stage of tightening or an early stage of loosening, turn off the electric drive assembly, grip the handle section of the outer shell to turn the socket wrench manually. When the power output 31 rotates, the worm 2 and the worm gear 3 lock with each other so that the worm 2 and the worm gear 3 do not rotate, thus, any reaction force from the fastener cannot be transmitted to the speed reduce assembly, thus facilitating a smooth operation of tightening or loosen when a relative large force is applied to the fastener.

[0041] In the embodiment of Figures 6 and 7, the speed reduce assembly includes a re-direction assembly and a reduce assembly connected together. The re-direction assembly is used to change direction or angle of the transmission. The re-direction assembly is connected to the electric drive assembly. The reduce assembly is connected to the worm 3 of the self lock assembly.

[0042] According to the present embodiment, the re-direction assembly may include a gear assembly having a first bevel gear 50 and a second bevel gear 60. The first bevel gear 50 and the second bevel gear 60 mesh with each other. The first bevel gear 50 is coupled to an output of the electric drive assembly. The second bevel gear 60 is coupled to the reduce assembly. The reduce assembly may also include a first gear 70 and a second gear 80 meshing with the first gear 70. The first gear 70 and the second bevel gear 60 of the re-direction assembly are positioned in co-axial manner. In one embodiment, the first gear 70 and the second bevel gear 60 are both coupled to a cylindrical body to form a machine part. The cylindrical body may be a hollow cylinder. A position rod 13 may be inserted through the hollow cylinder to secure the first gear 70 and the second bevel gear 60 to the outer shell 1 . The position rod 13 may be secured to a protruding plate 12A on the lid 12'. The second gear 80 is coaxially connected with the worm 2 of the self lock assembly. In one embodiment, the worm 2 is hollow with a longitudinal central opening. The second gear 80 includes a central shaft 801 . The central shaft 801 may be inserted into the central opening of the worm 2 and secured therein by an alignment structure. Exemplary alignment structure may be a dowel pin and an alignment opening. As shown in Figure 8, the second gear 80 may include two dowel pins formed thereon or attached thereto. The worm 2 has two alignment notches 21 , 22 corresponding to the two dowel pins on the second gear 80. In one embodiment, the second gear 80 may be hollow having a longitudinal central opening. A cylindrical pole 14 may be inserted into the central opening of the second gear 80. As shown in Figures 6 and 7, the cylindrical pole 14 may be secured to the recess body 1 1 ' of the outer shell 1 . The diameter of the first gear 70 is smaller than the diameter of the second gear 80 to facilitate speed reducing. In the present embodiment, the ratio of the diameter of the diameter of the first gear 70 over the diameter of the second gear 80 may be selected according to operation requirement.

[0043] In one embodiment, the electric drive assembly includes a power source 90, a switch 101 , and an electric motor 100. An output of the electric motor 100 is connected to the first bevel gear 50 of the re-direction assembly. In this embodiment, the output of the electric motor 100 is an output shaft as shown in Figure 7. In one embodiment, the switch 101 may be a three-position switch having a front position, a middle position and a back position. When the switch 101 is at the front position, the electric motor 100 drives the worm 2 to rotate along clockwise direction. When the switch 101 is at the back position, the electric motor 100 drives the worm 2 to rotate along counter clockwise direction. When the switch is at the middle position, the electric motor 100 is turned off so that the socket wrench may be operated manually to tighten or loosen a fastener. The power source 90 may be one or more batteries. In one embodiment, the power source 90 may include four rechargeable batteries. The outer shell 1 includes a battery recharge interface 102 to facilitate battery recharge. The power source 90 may be any suitable power source.

[0044] In one embodiment, the electric drive assembly may further an overload protection to prevent damage to the electric motor 100 from overloading. The overload protection may be installed inside the outer shell 1 .

Embodiment 3

[0045] Figures 9 -1 1 and 12a-12c schematically illustrate another energy saving electric socket wrench according to one embodiment of the present disclosure. The electric socket wrench may include a handle. As shown in Figure 9, the handle may have a power input 310 for griping or applying forces to tighten or loosen a fastener.

[0046] The electric socket wrench also includes a power output to connect with a fastener to be loosened or tightened. During operation, the power output and the handle of the electric socket wrench are fixedly connected without rotation relative to each other. The power output and the power input are located at opposite ends of the socket wrench.

[0047] The handle includes a hollow shell body. A speed increase assembly may be disposed inside the hollow shell body. The speed increase assembly may be used to rapidly rotate a fastener during an early stage of fastening or a final stage of loosening to save energy. The speed increase assembly may be connected to the power output. Alternatively, the speed increase assembly may be formed in a unitary body with the power output. The speed increase assembly is designed such that any reaction force from applied to the power output cannot rotate the speed increase assembly in a reverse direction. [0048] In one embodiment, the handle may include two chamber body sections 31 1 ' and 312'. The two chamber body sections 31 1 ' and 312' may attach to each other and enclose a chamber to hold the speed increase assembly. The two chamber body sections 31 1 ' and 312' may open along a longitudinal direction of the handle. The two chamber body sections 31 1 ' and 312' may be identical or of different sizes.

[0049] The electric socket wrench further includes a head pivotably connected to the handle. The head may include a head cover 321 and a head seat 322. The head cover 321 and the head seat 322 may be removably assembled together to form the head. The head includes a chamber. The power output extends outside the head.

[0050] As shown in Figure 10, the head and the handle are connected by a shaft 17. The head may pivot about the shaft 17 relative to the handle for an angle between 0 degree and 90 degree. The head may rotate about the shaft 17 to a desired position and remain in the desired position. When the head rotates relative to the handle, the power output rotates along with the head therefore allowing adjustment of the direction of the power output. The relative rotation of the head and the handle enables the socket wrench to operate at a widened range of angles. A position element or position assembly, such as a ball and spring position assembly or other structures, may be used to maintain the position of the head.

[0051] The power output may be a socket or a column configured to connect to a socket. In the embodiment of Figure 10, the power output is a squared column to securely connect to a socket. A socket may be encased around the squared column to tighten or loosen a fastener. Since a large force is usually applied to turn the handle during the early stage of loosening or the final stage of tightening, the power output and the handle are fixedly connected during operation to insure efficient power transfer. Any suitable connection between the power output and handle may be used.

[0052] A speed increase assembly according to one embodiment of the present disclosure is described in detail below. However, the present disclosure is not limited to this embodiment. Any change devised by persons skilled in the art falls within the scope of the present disclosure.

[0053] The speed increase assembly may include a power input and a self lock assembly. The self lock assembly includes at least one drive sub- assembly and one driven sub-assembly. The drive sub-assembly is connected to the power input. An input force from the power input drives and rotates the drive sub-assembly. The drive sub-assembly then drives the driven sub-assembly. The driven sub-assembly may be connected to or formed together with the power output to transfer the input force to a fastener and turn the fastener. However, the reaction force from the fastener will not drive and rotate the drive sub-assembly. Figure 10 illustrates one exemplary embodiment of the drive sub-assembly. The drive sub-assembly includes a worm 2 and a worm gear 3 that meshes with the worm 2. The worm gear 3 and the power output 31 are formed in one piece. Alternatively, the worm gear 3 may be fixedly coupled to the power output 31 .

[0054] In this embodiment, the power input may be an electric powered input. The electric powered input may include an electric drive assembly and a speed reduce assembly. The speed reduce assembly may be connected with the drive sub-assembly, i.e. the worm 2.

[0055] In the present disclosure, the speed reduce assembly includes a re-direction assembly and a reduce assembly connected to the re-direction assembly. The reduce assembly is configured to reduce rotational speed and increase torque or rotational force. The re-direction assembly is connected to the electric powered input. The reduce assembly is connected to the worm 2 of the self lock assembly.

[0056] In one embodiment, the re-direction assembly includes a first bevel gear 50' and a second bevel gear 60'. The first bevel gear 50' is coupled to an output of the electric powered input. The second bevel gear 60's is coupled to the reduce assembly.

[0057] The reduce assembly may be a gear assembly including a first gear 70' and a second gear 80' meshing with the first gear 70'. The first gear 70' and the second bevel gear 60' of the re-direction assembly are positioned in co-axial manner. In one embodiment, the first gear 70' and the second bevel gear 60' are both coupled to a hollow cylindrical body to form a machine part. The machine part may be secured the connection point of the handle and the head through a shaft 16 of an intermediate gear. The second gear 80' is coaxially connected with the worm 2 of the self lock assembly. In one embodiment, the worm 2 is hollow with a longitudinal central opening. The second gear 80' includes a central shaft 801 '. The central shaft 801 ' may be inserted into the central opening of the worm 2 and secured therein by an alignment structure. The head may pivot relative to the handle through the shaft 17. The diameter of the first gear 70' is smaller than the diameter of the second gear 80' to facilitate speed reducing. In the present embodiment, the ratio of the diameter of the diameter of the first gear 70' over the diameter of the second gear 80' may be selected according to operation requirement.

[0058] In one embodiment, the electric drive assembly includes sequentially connected a power source 90', a switch 101 ', and an electric motor 100'. An output of the electric motor 100' is connected to the first bevel gear 50' of the re-direction assembly. In this embodiment, the output of the electric motor 100' is an output shaft as shown in Figure 10. In one embodiment, the switch 101 ' may be a three-position switch having a front forward position, a middle stop position and a back reverse position. When the switch 101 ' is at the middle stop position, push the front forward position of the switch 101 ', the electric motor 100' will drive the worm 2 to rotate along clockwise direction; and push the back reverse position of the switch 101 ', the electric motor 100' will drive the worm 2 to rotate along counter clockwise direction. When switch 101 ' is at the front forward position or the back reverse position, push the front forward position of the back reverse position to set the switch 101 ' to the middle stop position therefore turning off the electric motor 100'. The switch 101 ' allows the socket wrench to turn a fastener by forward rotation and reverse rotation therefore convenient to use. The forward position and the reverse position may be switched. The electric drive assembly further includes a switch seat 102' matching the switch 101 '. The power source 90' may be rechargeable batteries. The outer shell 1 includes a battery recharge interface 14 to facilitate battery recharge. In one embodiment, the electric drive assembly may further include a battery protection board 13. The power source 90' may be other suitable power source according to available technology.

[0059] The electric drive assembly further includes an overload protection assembly disposed in the outer shell 1 . The overload protection assembly is configured to prevent damage caused by overloading. The electric drive assembly further includes a battery status light 15 to indicate the status of the batteries and provide reminders for recharge.

[0060] To tighten a bolt or nut using the electric socket wrench according to this embodiment, first push the switch 101 ' to the front forward position so that the electric motor 100' rotates the power output 31 through the power transmission assembly to pre-tighten the bolt or nut as shown in Figure 1 1 . When the pre-tighten stage ends, push the switch 101 ' to the middle stop position to turn off the electric motor 100', then turn the power input 310 of the handle to transfer power directly to the power output 31 and perform the final stage of tightening. When the bolt or nut to be turned is in a slanted position, manually rotate the head about the shaft 17 relative to the handle. Figures 12a, 12b, 12c schematically illustrate various angles between the handle and the head. Therefore, the angle of applied force may be adjusted according the position of the bolt or nut before tightening the bolt or nut by the operation described above.

[0061] To loosen a bolt or nut using the electric socket wrench according to this embodiment, first turn the handle at the power input 310 to transfer the power directly to the power output 31 to start loosening the bolt or nut. Then push the switch 101 ' to the back reverse position so that the electric motor 100' rotates the power output 31 through the power transmission assembly to completely loosen or remove the bolt or nut as shown in Figure 1 1. When the work is complete, push the switch 101 ' to the middle stop position.

[0062] It should be noted that the above described operations are only examples. Embodiments of the present disclosure are not limited to the above examples.

[0063] The present disclosure provides an energy saving socket wrench which improves the operation of fastener handling when large forces are not necessary, for example during an early stage of tightening or a final stage of loosening. The socket wrench according to the present disclosure is fast and easy to operate, with simple structure, convenient to manufacture, with a low cost, may be used in a wide range of fields.

[0064] While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.