Fixed Torque Module for Power Tools

Abstract

To provide a fixed torque module which can output torque having magnitudes which varies between normal rotation and reverse rotation, maintains high rotation speed and high working efficiency, and achieve reduction of manufacturing costs.SOLUTION: A fixed torque module used in a power tool includes an annular transmission mechanism, two buffer units, an inner shaft unit, and an outer shaft unit. The annular transmission mechanism has a body, a connection part, a center shaft, two storage chambers, and two striking blocks. The two buffer units are arranged so as to occupy a part of the two storage chambers and reserve storage spaces in the storage chambers. The inner shaft unit has an inner disc body, two inner convex blocks, a shaft groove, a shaft part, and a fitting part. The center shaft of the annular transmission mechanism is inserted into the shaft grove. The outer shaft unit has an outer disc body, two outer convex blocks, a shaft sleeve, an operation end, a shaft hole, and a fitting groove. The fitting part of the inner shaft unit is fitted into the fitting groove.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a power tool, and more particularly to a fixed torque module used in a power tool.

Background Art

[0002] Power tools such as air tools, electric tools, and hydraulic drive tools tighten or loosen parts such as bolts or nuts by a tool head connected to a rotating shaft. When the rotating shaft is reversed to loosen a nut or bolt, it is necessary to generate a large torque in the power tool. To tighten a nut or bolt, if the torque generated by the forward rotation of the rotating shaft is not controlled within an appropriate range, the bolt or nut may be damaged due to being tightened too strongly, or it may often become difficult to attach or detach. Also, when attaching a tire, if the tightening torques of a plurality of nuts do not match, the stress magnitudes are not uniform, so the nuts that vibrate over a long period of time are likely to become loose, leading to danger.

[0003] In the case of an air tool that controls the output shaft torque by a hydraulic principle or a planetary gear reduction mechanism, high-precision machining of the structure is required, so the cost is high. Also, since the rotational speed is relatively low, the working efficiency is not very good. That is, finding a method that can control the magnitude of the output torque while maintaining high-speed rotation, and at the same time smoothing the machining and reducing the manufacturing process is a technical problem waiting to be solved in the industry.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The main object of the present invention is to provide a fixed torque module that can be applied to a power tool and output different magnitudes of torque by forward and reverse rotations.

[0005] Another object of the present invention is to provide a fixed torque module that can be applied to a power tool to increase the rotational speed and working efficiency and reduce the manufacturing cost.

Means for Solving the Problems

[0006] To solve the above problems, a fixed torque module is applied to a power tool. The power tool has an output part. The fixed torque module includes an annular transmission mechanism, two buffer units, an internal shaft unit, and an external shaft unit. The annular transmission mechanism has a main body, a connection part, a central shaft, two storage chambers, and two striking blocks. The connection part is connected to the output part of the power tool and is formed by extending from the main body. The central shaft is formed by extending from the main body in the direction opposite to the connection part. The two storage chambers are separately formed on both sides of the main body and the central shaft. The two striking blocks are formed by extending from the main body and are arranged so as to be away from the central shaft from the two storage chambers. The two buffer units occupy a part of the two storage chambers and are arranged to reserve a storage space in the storage chambers. The internal shaft unit has an internal disk body, two internal convex blocks, a shaft groove, a shaft part, and a fitting part. The two internal convex blocks are formed by extending from the internal disk body into the two storage spaces. The shaft groove is formed in the internal disk body. The central shaft of the annular transmission mechanism is inserted into the shaft groove. The shaft part is formed by extending from the internal disk body in the direction opposite to the two internal convex blocks. The fitting part is formed at the end part of the shaft part. The external shaft unit has an external disk body, two external convex blocks, a shaft sleeve, an operating end part, a shaft hole, and a fitting groove. The two external convex blocks are formed by extending from the external disk body to the main body of the annular transmission mechanism and are arranged outside the internal disk body. The shaft sleeve is formed by extending from the external disk body in the direction opposite to the two external convex blocks. The operating end part is arranged at the end part of the shaft sleeve. The shaft hole is formed by extending from the external disk body to the inside of the shaft sleeve. The shaft part of the internal shaft unit is inserted into the shaft hole. The fitting groove is formed at the inner end part of the shaft hole. The fitting part of the internal shaft unit fits into the fitting groove. The internal disk body is arranged between the external disk body and the main body of the annular transmission mechanism. When the annular transmission mechanism rotates in the first direction, the two striking blocks collide with the two external convex blocks and then transmit the rotational force to the external shaft unit. When the annular transmission mechanism rotates in the second direction opposite to the first direction, the two buffer units collide with the two internal convex blocks and then transmit the rotational force to the internal shaft unit, and transmit the rotational force to the external shaft unit through the fitting part and the fitting groove.

[0007] Due to the above-described structural features, when the fixed torque module rotates forward (rotates in the second direction) or reverses (rotates in the first direction), torques of different magnitudes can be output, and high rotational speed and good working efficiency can be maintained, so that the manufacturing cost can be reduced.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7a

Figure 7b

Figure 8a

Figure 8b

Figure 9

Figure 10

Best Mode for Carrying Out the Invention

[0009] Hereinafter, the fixed torque module used in the power tool according to the present invention will be described based on three embodiments and drawings.

[0010] (First Embodiment) As shown in FIGS. 1 to 4, the fixed torque module 1 according to the first embodiment of the present invention is mounted in the power tool 2. The power source of the power tool 2 is not particularly limited, and it may be electrically, pneumatically or hydraulically driven. In the present embodiment, the power tool 2 is an air tool.

[0011] The power tool 2 operates the striking mechanism via the air motor 3, and the rotational power of the air motor 3 is transmitted forward by the striking mechanism. In FIG. 2, the front is denoted by F. The rear is denoted by B. The power tool 2 has an output portion 4. The output portion 4, that is, the striking mechanism transmits the rotational power of the air motor 3. Since the air motor 3 and the striking mechanism of the power tool 2 are not technical features of the present invention, detailed description thereof will be omitted. In another embodiment, the output shaft 5 of the air motor 3 or another component can be used as the striking mechanism, that is, the output portion 4.

[0012] The fixed torque module 1 includes an annular transmission mechanism 10, two buffer units 20, an internal shaft unit 30, and an external shaft unit 40.

[0013] The annular transmission mechanism 10 is manufactured by metal processing and has a cylindrical main body 11, a connecting portion 12, a central shaft 14, two storage chambers 16 and two striking blocks 18. The connecting portion 12 is connected to the output portion 4 of the power tool 2 and is formed by extending rearward from the main body 11. The central shaft 14 is formed by extending forward from the main body 11, that is, in the direction opposite to the connecting portion 12. The two storage chambers 16 are separately formed on both sides of the main body 11 and the central shaft 14. The two striking blocks 18 are formed by extending forward from the main body 11 and are arranged so as to be separated from the central shaft 14 from the two storage chambers 16. The connecting portion 12 has a columnar shaft portion 121 and two impact portions 122. The two impact portions 122 are formed by extending from the columnar shaft portion 121 and can withstand the intermittent strikes of the striking mechanism. The connecting portion 12 is provided such that its structure corresponds to the output portion 4. In other words, if the cross-section of the outer peripheral edge portion of the columnar shaft portion 121 is non-circular, it can receive the rotational power of the output portion 4. The central shaft 14 is located at the center of rotation of the main body 11. The two storage chambers 16 have the same shape and correspond to the central shaft 14. The two striking blocks 18 are arranged outside the two storage chambers 16, their positions correspond to the central shaft 14, and their shapes are arc-shaped, but are not limited thereto. That is, the shapes of the storage chambers 16 and the striking blocks 18 may vary depending on the situation.

[0014] The two buffer units 20 are arranged to occupy a part of the two storage chambers 16 and reserve a storage space 17 in the storage chambers 16, and each has an arc-shaped elastic body 22, two sheet-like elastic portions 24 and a block 26. The elastic body 22 is made of a natural polymer material or a synthetic polymer material that can be elastically deformed and absorb impacts, such as rubber or silicon. The two sheet-like elastic portions 24 are made of a metal material and are connected in parallel to the convex side 221 of the elastic body 22. As shown in FIG. 7b, since there is a gap 161 between the concave side 222 of the elastic body 22 and the inner wall of the storage chamber 16, the elastic body 22 can be greatly deformed and the buffer space can be increased. The two sheet-like elastic portions 24 can produce a buffer effect by the support of the elastic body 22. The block 26 is made of a metal material and has a considerable thickness and impact resistance, so the two sheet-like elastic portions 24 are protected by the block 26 and are less likely to be damaged by continuous impacts.

[0015] The inner shaft unit 30 has an inner disk body 31, two inner convex blocks 32, a shaft groove 34, a shaft portion 35, and a fitting portion 38. The two inner convex blocks 32 are formed to extend from the rear side of the inner disk body 31 into the two storage spaces 17. The shaft groove 34 is formed on the rear side of the inner disk body 31. The central shaft 14 of the annular transmission mechanism 10 is inserted into the shaft groove 34. The shaft portion 35 is formed to extend forward from the inner disk body 31, that is, in a direction opposite to the two inner convex blocks 32. The fitting portion 38 is formed at the end portion 36 of the shaft portion 35. The two inner convex blocks 32 are arc-shaped elongated blocks, and the two blocks 26 are arranged side by side to maintain the two blocks 26 between the sheet-like elastic portion 24 and the inner convex block 32. In another embodiment, if the thickness of the two sheet-like elastic portions 24 increases, the arrangement of the block 26 can be omitted, and the two sheet-like elastic portions 24 can be positioned between the inner convex block 32 and the elastic body 22. The elastic body 22 and the sheet-like elastic portion 24 protrude in an arc shape toward the inner convex block 32. The central shaft 14 of the annular transmission mechanism 10 is inserted into the shaft groove 34 to maintain the inner shaft unit 30 and the annular transmission mechanism 10 coaxially and can be rotated. Since the shape of the shaft portion 35 gradually increases from the middle portion 37 to both ends, the middle portion 37 is twisted and deformed to absorb a part of the rotational torque, and by maintaining sufficient structural strength, it can withstand the rotational force and avoid breaking. The fitting portion 38 has two flat surfaces 39. Specifically, if the cross section of the outer peripheral edge portion of the fitting portion 38 is non-circular, rotational power can be transmitted to the outer shaft unit 40.

[0016] The external shaft unit 40 has an external disk body 41, two external convex blocks 42, a shaft sleeve 44, an operating end 46, a shaft hole 47, and a fitting groove 49. The two external convex blocks 42 are formed to extend from the external disk body 41 to the main body 11 of the rear annular transmission mechanism 10 and are arranged outside the inner disk body 31. The shaft sleeve 44 is formed to extend forward from the external disk body 41, that is, in the direction opposite to the two external convex blocks 42. The operating end 46 is arranged at the end portion 45 of the shaft sleeve 44. The shaft hole 47 is formed to extend from the external disk body 41 to the inside of the shaft sleeve 44. The shaft portion 35 of the internal shaft unit 30 is inserted into the shaft hole 47. The fitting groove 49 is formed at the inner end portion 48 of the shaft hole 47. The fitting portion 38 of the internal shaft unit 30 fits into the fitting groove 49. As shown in FIG. 5, the two external convex blocks 42 are arc-shaped elongated blocks. The two external convex blocks 42 and the two striking blocks 18 are arranged to cross outside the internal shaft unit 30. The shaft portion 35 of the internal shaft unit 30 is inserted into the shaft sleeve 44 from the shaft hole 47. The operating end 46 is square prism-shaped, but is not limited thereto and may be tubular. If the cross section of the outer peripheral edge portion of the operating end 46 is non-circular, the operating end 46 can transmit rotational power. When proceeding with the work, if a tool head (not shown in the figure), for example, a socket wrench, is fitted to the operating end 46, a nut or a bolt can be turned. As shown in FIG. 5, since the fitting groove 49 has a shape of the inner peripheral edge portion corresponding to the fitting portion 38 and has two flat surfaces 491, the external shaft unit 40 is driven by the internal shaft unit 30. In another embodiment, since the cross section of the inner peripheral edge portion of the fitting groove 49 is non-circular, the external shaft unit 40 can receive the rotational force of the internal shaft unit 30.

[0017] As shown in FIGS. 2 and 6, the inner disk body 31 is disposed between the outer disk body 41 and the main body 11 of the annular transmission mechanism 10. FIG. 7a is a perspective view showing a state where the user reverses the output part 4 by the power tool 2. When the user rotates (reverses) the output part 4 of the power tool 2 counterclockwise to loosen the nut, as shown in FIG. 7a, the annular transmission mechanism 10 rotates in the first direction D1 (i.e., counterclockwise) after receiving the driving force of the output part 4, and the two striking blocks 18 collide with the two external convex blocks 42 to transmit the rotational force to the external shaft unit 40. Since the two striking blocks 18 and the two external convex blocks 42 are far from the central axis 14, that is, the distance between the force point and the fulcrum is large, a relatively large rotational torque can be generated. As shown in FIG. 7b, since there is a gap between the inner wall of the storage chamber 16 of the annular transmission mechanism 10 and the two inner convex blocks 32, the rotational force of the annular transmission mechanism 10 is not transmitted to the inner shaft unit 30.

[0018] When the user rotates the output part 4 of the power tool 2 clockwise (forward rotation) to tighten the nut, as shown in Fig. 8a, the annular transmission mechanism 10 rotates in the second direction D2 opposite to the first direction D1 (i.e., clockwise), and in order to separate the two striking blocks 18 from the two external convex blocks 42, the rotational force is not transmitted from the annular transmission mechanism 10 to the external shaft unit 40. As shown in Fig. 8b, if the two blocks 26 of the two buffer units 20 are made to collide with the two internal convex blocks 32, the rotational force is transmitted from the annular transmission mechanism 10 to the internal shaft unit 30 and then to the external shaft unit 40 via the fitting part 38 and the fitting groove 49. Since the two internal convex blocks 32 are close to the central axis 14, that is, the distance between the force point and the fulcrum is small, the rotational torque is relatively small. Since the fitting part 38 and the fitting groove 49 are close to the axis of the central axis 14, the rotational torque is reduced. The elastic body 22 and the sheet-like elastic part 24 of the buffer unit 20 can absorb the rotational force of the annular transmission mechanism 10. Since the shaft part 35 of the internal shaft unit 30 has an elongated structure, the shaft part 35 can be twisted and deformed to absorb the torque. Due to the above-described structural features, the output forward rotation torque can be reduced. Specifically, according to the test results, it was found that the forward rotation torque drops to 1 / 4 of the reverse rotation torque. That is, if the output reverse rotation torque is 400 Newton meters, the output forward rotation torque is 100 Newton meters. Since the forward rotation torque is adjusted according to the customer's needs, an output of a fixed torque can be achieved.

[0019] Summarizing the above, the fixed torque module 1 according to the present invention can output torques of different magnitudes depending on forward and reverse rotations. Since the external shaft unit 40 rotates together with the output part 4 of the power tool 2, it does not reduce the rotational speed during output, and maintains the rotational speed between 8000 and 9000 rpm when rotating forward or reverse, and can maintain good working efficiency. Compared with the hydraulic mechanism, the processing accuracy of the accessories is not so high, so not only can the simplification of processing and the reduction of manufacturing costs be achieved, but also it has the power to form a market.

[0020] (Second Embodiment) FIG. 9 is a perspective view showing a fixed torque module 1a according to the second embodiment of the present invention. The differences from the first embodiment are as follows. In the second embodiment, the connection portion 12a of the annular transmission mechanism 10a is composed of a hexagonal columnar shaft portion 121a for corresponding to the output portions of different power tools.

[0021] (Third Embodiment) FIG. 10 is a perspective view showing a fixed torque module 1b according to the third embodiment of the present invention. The differences from the first embodiment are as follows. In the third embodiment, the connection portion 12b of the annular transmission mechanism 10b has a square fitting hole 13b for corresponding to the output portions of different power tools. Due to the above-described structural features, the fixed torque module 1b can be put on the square columnar output shaft of a commercially available power tool. That is, the application range of the present invention can be increased.

[0022] The connection portion of the annular transmission mechanism 10 is not limited to the above, and may be a columnar shaft portion whose cross section of the outer peripheral edge portion is non-circular. The fitting hole is not limited to the above, and the cross section of the inner peripheral edge portion may be non-circular. The buffer unit is not limited to the above, and may be a member capable of absorbing an acting force, such as a spring.

[0023] As described above, the present invention is not limited to the above embodiments, and can be implemented in various forms without departing from the spirit of the invention.

Explanation of Reference Numerals

[0024] 1, 1a, 1b: Fixed torque module 2: Power tool 3: Air motor 4: Output portion 5: Output shaft 10, 10a, 10b: Annular transmission mechanism 11: Main body 12, 12a, 12b: Connection portion 121, 121a: Columnar shaft portion 122: Impact-receiving portion 13b: Fitting hole 14: Central axis 16: Storage chamber 161: Gap 17: Storage space 18: Impact block 20: Buffer unit 22: Elastic body 221: Convex side 222: Concave side 24: Sheet-like elastic part 26: Block 30: Internal shaft unit 31: Internal disk body 32: Internal convex block 34: Axial groove 35: Shaft part 36: End part 37: Middle part 38: Fitting part 39: Flat surface 40: External shaft unit 41: External disk body 42: External convex block 44: Shaft sleeve 45: End part 46: Actuating end part 47: Axial hole 48: Inner end part 49: Fitting groove 491: Flat surface B: Rear D1: First direction D2: Second direction F: Front

Claims

1. A fixed torque module used in a power tool having an output part, comprising an annular transmission mechanism, two buffer units, an internal shaft unit, and an external shaft unit, wherein the annular transmission mechanism has a main body, a connection part, a central shaft, two storage chambers, and two striking blocks; the connection part is connected to the output part of the power tool, is formed by extending from the main body; the central shaft is formed by extending from the main body in a direction opposite to the connection part; the two storage chambers are separately formed inside the main body and on both sides of the central shaft; the two striking blocks are formed by extending from the main body and are arranged so as to be away from the central shaft from the two storage chambers, the two buffer units occupy a part of the two storage chambers and are arranged to reserve a storage space in the storage chambers, the internal shaft unit has an internal disk body, two internal convex blocks, a shaft groove, a shaft part, and a fitting part; the two internal convex blocks are formed by extending from the internal disk body into the two storage spaces; the shaft groove is formed in the internal disk body; the central shaft of the annular transmission mechanism is inserted into the shaft groove; the shaft part is formed by extending from the internal disk body in a direction opposite to the two internal convex blocks; the fitting part is formed at the end part of the shaft part, the external shaft unit has an external disk body, two external convex blocks, a shaft sleeve, an operating end part, a shaft hole, and a fitting groove; the two external convex blocks are formed by extending from the external disk body to the main body of the annular transmission mechanism and are arranged outside the internal disk body; the shaft sleeve is formed by extending from the external disk body in a direction opposite to the two external convex blocks; the operating end part is arranged at the end part of the shaft sleeve; the shaft hole is formed by extending from the external disk body into the inside of the shaft sleeve; the shaft part of the internal shaft unit is inserted into the shaft hole; the fitting groove is formed at the inner end part of the shaft hole; the fitting part of the internal shaft unit is fitted into the fitting groove, the internal disk body is arranged axially between the external disk body and the main body of the annular transmission mechanism. When the annular transmission mechanism rotates in the first direction, the two striking blocks collide with the two external convex blocks and then transmit the rotational force to the external shaft unit. There is a gap between the inner wall of the storage chamber of the annular transmission mechanism and the two internal convex blocks, and the rotational force is not transmitted from the annular transmission mechanism to the internal shaft unit. When the annular transmission mechanism rotates in the second direction opposite to the first direction, the two buffer units collide with the two internal convex blocks and then transmit the rotational force to the internal shaft unit. Subsequently, the rotational force transmitted to the internal shaft unit by the fitting portion and the fitting groove is transmitted to the external shaft unit. Since the two striking blocks separate from the two external convex blocks, the rotational force is not transmitted from the annular transmission mechanism to the external shaft unit. The fixed torque module is a module that outputs torques of different magnitudes in the forward rotation, which is the second direction, and the reverse rotation, which is the first direction. The operating end rotates the tool head fitted to the operating end in the forward or reverse direction. Since the distances of the two external convex blocks from the central axis are greater than those of the two internal convex blocks, the rotational torque in the first direction is greater than the rotational torque in the second direction. A fixed torque module used for a power tool, characterized in that.

2. The buffer unit has an elastic body and one or more sheet-like elastic parts, and one or more of the sheet-like elastic parts are located between the internal convex block and the elastic body. The fixed torque module used for the power tool according to claim 1, characterized in that.

3. The elastic body is made of a natural polymer material or a synthetic polymer material. The fixed torque module used for the power tool according to claim 2, characterized in that.

4. The buffer unit further has a block, and the block is located between the sheet-like elastic part and the internal convex block. The fixed torque module used for the power tool according to claim 2, characterized in that.

5. The elastic body and the sheet-like elastic part protrude in an arc shape toward the internal convex block. The fixed torque module used for the power tool according to claim 2, characterized in that.

6. The connecting portion of the annular transmission mechanism is composed of a columnar shaft portion with a non-circular cross-section at the outer peripheral edge, or has a fitting hole with a non-circular cross-section at the inner peripheral edge, and is a fixed torque module used for the power tool according to claim 1.

7. The shaft portion of the internal shaft unit is provided such that its shape gradually increases from the middle portion to both end portions, and is a fixed torque module used for the power tool according to claim 1.

8. The fitting portion of the internal shaft unit has a non-circular cross-section at the outer peripheral edge, The fitting groove of the external shaft unit has a non-circular cross-section at the inner peripheral edge, and is a fixed torque module used for the power tool according to claim 1.

9. The outer peripheral edge or the inner peripheral edge of the operating end portion has a non-circular cross-section, and is a fixed torque module used for the power tool according to claim 1.

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