Mechanical torque limiting wrench

Abstract

The application discloses a mechanical limited force torque wrench, which comprises a wrench head, a force applying handle, a piston, a constant force spring for applying elastic force to the piston, a force reducing gear set arranged in the force applying handle, a force transmitting rack connected with the wrench head and engaged with the force reducing gear set, a force releasing gear set arranged in the force applying handle and engaged with the force reducing gear set, a reset mechanism for disengaging the force releasing gear set when the wrench releases force, and a rolling element arranged on the reset mechanism and in contact with the piston. The mechanical limited force torque wrench has the advantages that the handle rotating angle can be larger, the constant force precision is improved, and the product life is prolonged.

Description

Technical Field

[0001] This invention belongs to the field of wrench technology, specifically, this invention relates to a mechanical torque limiting wrench. Background Technology

[0002] Existing mechanical torque limiters mostly use a method of limiting force by flipping a block, lever, or piston lever to push a constant force spring to unload the force. This method has low precision and short lifespan, and has the following disadvantages:

[0003] 1) such as Figure 8 As shown, the flip block and spring structure has the flip block located between the inner rod and the piston. The inner rod is fixedly connected to the wrench head. Due to the friction between the flip block and the handle groove, the force unloading response sensitivity is reduced. Wear of the flip block changes its shape, affecting the accuracy of the fixed force and resulting in a short product handle.

[0004] 2) such as Figure 9 As shown, the lever structure restricts the rotation angle within the hollow handle, reducing the feel of unloading force.

[0005] 3) such as Figure 10 As shown, in the lever-piston structure, due to the radial force on the piston loaded by the lever, there is a large friction between the piston and the hollow handle wall, which affects the sensitivity of the unloading response and also affects the accuracy of the constant force.

[0006] All of the above structures have the following characteristics: when unloading force, the spring compression stroke is large, the spring deformation is large, and it is prone to fatigue hardening, resulting in reduced accuracy. Summary of the Invention

[0007] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention provides a mechanical torque limiting wrench, the purpose of which is to improve the accuracy of force setting, extend its service life, and improve the feeling of force release.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a mechanical torque limiting wrench, comprising a wrench head, a force application handle, a piston, a constant force spring that applies an elastic force to the piston, a force reduction gear set disposed inside the force application handle, a force transmission rack connected to the wrench head and meshing with the force reduction gear set, a force unloading gear set disposed inside the force application handle and meshing with the force reduction gear set, a reset mechanism for disengaging from the force unloading gear set when the wrench is unloaded, and a rolling element disposed on the reset mechanism and in contact with the piston.

[0009] At least one set of the reducing gear assembly is provided.

[0010] The reducing gear set includes a first large gear and a first small gear arranged coaxially and rotating synchronously, with the diameter of the first large gear being larger than the diameter of the first small gear.

[0011] The force reduction gear set is provided in one set, with the first large gear meshing with the force unloading gear set and the first small gear meshing with the force transmission rack.

[0012] The force-reducing gear set shall be provided in at least two sets. The force-transmitting rack meshes with the first pinion of the nearest force-reducing gear set, and the first large gear of the force-reducing gear set meshes with the first pinion of the adjacent force-reducing gear set. The force-unloading gear set meshes with the first large gear of the nearest force-reducing gear set, and the first pinion of the force-reducing gear set meshes with the first large gear of the adjacent force-reducing gear set.

[0013] The unloading gear set includes a second large gear and a second small gear that are coaxially arranged and rotate synchronously, with the diameter of the second large gear being larger than the diameter of the second small gear.

[0014] The second large gear meshes with the reset mechanism, and the first small gear meshes with the reducing gear set.

[0015] The second large gear is an incomplete gear, and the reset mechanism includes a reset gear that meshes with the second large gear.

[0016] The reset mechanism also includes a rotating mechanism that is coaxial with and rotatable from the reset gear. The rolling element is disposed on the rotating mechanism, and a one-way mechanism is provided in the rotating mechanism or the reset gear.

[0017] The mechanical torque limiting wrench also includes a force adjustment mechanism disposed inside the force application handle, and the constant force spring is located between the piston and the force adjustment mechanism.

[0018] The mechanical torque limiter of the present invention reduces wear and improves the accuracy of force setting by setting a rolling element to contact the piston; moreover, the gear transmission reduces the spring compression force and improves the spring fatigue life, thereby increasing the service life of the product. Attached Figure Description

[0019] This manual includes the following figures, which illustrate the following:

[0020] Figure 1 This is a longitudinal sectional view of the mechanical torque limiting wrench of the present invention;

[0021] Figure 2 This is a cross-sectional view of the mechanical torque limiting wrench of the present invention;

[0022] Figure 3 This is a structural schematic diagram of the mechanical torque limiting wrench of the present invention;

[0023] Figure 4 This is a schematic diagram of the structure of the second largest gear;

[0024] Figure 5 This is a schematic diagram of the rotating mechanism;

[0025] Figure 6 This is a sectional view of the rotating mechanism;

[0026] Figure 7 It is an assembly drawing of the rotating mechanism and the rolling elements;

[0027] Figure 8 This is a schematic diagram of the structure of a torque wrench that uses a flipping block in the prior art;

[0028] Figure 9 This is a schematic diagram of a torque wrench using a lever structure in the prior art;

[0029] Figure 10 This is a schematic diagram of a torque wrench using a lever-piston structure in the prior art;

[0030] The markings in the diagram are as follows: 1. Wrench head; 2. Second shaft; 3. Force transmission rack; 5. Reducer gear set; 7. Unloading gear set; 8. Return gear; 9. Rotating mechanism; 10. One-way mechanism; 11. Rolling element; 12. Third shaft; 13. Fourth shaft; 14. First shaft; 15. Piston; 16. Constant force spring; 17. Force adjustment mechanism; 18. Force application handle; 19. Return spring. Detailed Implementation

[0031] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, in order to help those skilled in the art to have a more complete, accurate and in-depth understanding of the concept and technical solutions of the present invention, and to facilitate its implementation.

[0032] It should be noted that in the following embodiments, the terms "first", "second", "third" and "fourth" do not represent an absolute distinction in structure and / or function, nor do they represent the order of execution, but are merely for the convenience of description.

[0033] Example 1

[0034] like Figures 1 to 3 As shown, this embodiment provides a mechanical torque limiting wrench, including a wrench head 1, a force application handle 18, a piston 15, a constant force spring 16 that applies an elastic force to the piston 15, a force reduction gear set 5 disposed inside the force application handle 18, a force transmission rack 3 connected to the wrench head 1 and meshing with the force reduction gear set 5, a force unloading gear set 7 disposed inside the force application handle 18 and meshing with the force reduction gear set 5, a reset mechanism for disengaging from the force unloading gear set 7 when the wrench is unloaded, and a rolling element 11 disposed on the reset mechanism and in contact with the piston 15.

[0035] Specifically, such as Figures 1 to 3 As shown, the force-applying handle 18 is a hollow tubular structure. The wrench head 1 is located outside the force-applying handle 18. The force-transmitting rack 3 is mounted on the force-applying handle 18 via the second shaft 2. One end of the force-transmitting rack 3 is fixedly connected to the wrench head 1, and the other end of the force-transmitting rack 3 is provided with a tooth groove that meshes with one end of the force-reducing gear set 5. When the force-reducing gear set 5 cannot rotate, the force-transmitting rack 3 and the wrench head 1 cannot rotate around the second shaft 2. The operating force acting on the force-applying handle 18 drives the wrench head 1 to rotate through the second shaft 2, thereby causing the entire mechanical torque-limiting wrench to rotate and perform tightening operations.

[0036] like Figure 1 and Figure 2 As shown, in this embodiment, one set of reducing gear set 5 is provided. The reducing gear set 5 includes a first large gear and a first small gear that are coaxially arranged and rotate synchronously. The diameter of the first large gear is larger than the diameter of the first small gear. The first large gear and the first small gear are arranged on the third shaft 12, which is arranged on the force application handle 18. The axes of the third shaft 12 and the second shaft 2 are parallel. The first large gear and the first small gear are coaxially fixedly connected. The first large gear meshes with the unloading gear set 7, and the first small gear meshes with the force transmission rack 3.

[0037] like Figure 1 and Figure 2 As shown, the unloading gear set 7 includes a second large gear and a second small gear that are coaxially arranged and rotate synchronously. The diameter of the second large gear is larger than the diameter of the second small gear. The second large gear and the second small gear are mounted on a fourth shaft 13, which is mounted on a force application handle 18. The axes of the fourth shaft 13, the third shaft 12, and the second shaft 2 are parallel, with the third shaft 12 located between the second shaft 2 and the fourth shaft 13. The second large gear and the second small gear are coaxially fixedly connected. The second large gear meshes with the reset mechanism, and the first small gear meshes with the second large gear of the unloading gear set 5.

[0038] like Figure 1 , Figure 2 and Figure 4 As shown, the second large gear is an incomplete gear. The reset mechanism includes a reset gear 8 that meshes with the second large gear. The reset gear 8 is a cylindrical gear. The teeth of the second large gear do not cover the entire pitch circle. The second large gear has a toothed area with evenly distributed teeth and a toothless area with missing teeth. The toothed area meshes with the reset gear 8. During tightening, the reset gear 8 meshes with the toothed area of ​​the second large gear, and the second large gear can drive the reset gear 8 to rotate. When the tightening force reaches the preset value, the wrench needs to release the force. At this time, the second large gear rotates to the state where the toothless area is opposite the reset gear 8, and the second large gear can no longer drive the reset gear 8 to rotate.

[0039] like Figure 1 and Figure 2 As shown, the reset mechanism also includes a rotating mechanism 9 that is coaxial with and rotatable from the reset gear 8. The rotating mechanism 9 and the reset gear 8 are mounted on the first shaft 14, which is mounted on the force application handle 18. The axes of the first shaft 14, the fourth shaft 13, the third shaft 12, and the second shaft 2 are parallel. The first shaft 14 is located between the fourth shaft 13 and the piston 15.

[0040] like Figure 1 and Figure 2 As shown, piston 15 is movably disposed inside force-applying handle 18. Piston 15 can move along the length of force-applying handle 18. Force spring 16 is used to apply an elastic force to piston 15 to keep it in contact with rolling element 11. Force spring 16 pushes piston 15 to move. Rolling element 11 is rotatably disposed on rotating mechanism 9. The axis of rolling element 11 is parallel to the axis of first shaft 14. Piston 15 is located between rolling element 11 and force spring 16. Rolling element 11 is a bearing or roller. The outer circular surface of rolling element 11 is in contact with end face of piston 15. Rolling friction is formed between rolling element 11 and piston 15, which can reduce wear and help improve the accuracy of force application.

[0041] like Figure 1 and Figure 2 As shown, the reset gear 8 and the rotating mechanism 9 can rotate relative to each other, and the reset gear 8 and the rotating mechanism 9 can only rotate relative to each other in one direction. The rotating mechanism 9 or the reset gear 8 is provided with a one-way mechanism 10, which is a one-way bearing or a one-way ratchet. The one-way mechanism 10 is provided between the rotating mechanism 9 and the first shaft 14 or between the reset gear 8 and the first shaft 14.

[0042] If the one-way mechanism 10 is located between the rotating mechanism 9 and the first shaft 14, then the reset gear 8 is fixedly connected to the first shaft 14. The first shaft 14 is rotatably mounted on the force application handle 18. The one-way mechanism 10 and the rotating mechanism 9 are connected to the first shaft 14. The one-way mechanism 10 has two states depending on the direction of rotation: a locked state and a rotating state. In the tightening direction, the inner and outer rings of the one-way mechanism 10 cannot rotate relative to each other. In this state, the rotating mechanism 9 and the first shaft 14 are circumferentially fixed, and the reset gear 8, the rotating mechanism 9, and the first shaft 14 can rotate synchronously. The reset gear 8 drives the rotating mechanism 9 to rotate around its axis and transmits torque through the first shaft 14. The torque from the force transmission rack 3 is transmitted sequentially to the reset gear 8 and the rotating mechanism 9 through the reducing gear set 5 and the unloading gear set 7. In the loosening direction, the inner and outer rings of the one-way mechanism 10 can rotate freely, the one-way mechanism 10 slips out, and cannot transmit torque. The reset gear 8 and the rotating mechanism 9 can rotate relative to each other, but cannot transmit torque.

[0043] like Figure 1 and Figure 2As shown, the mechanical torque limiter of the present invention also includes a force adjustment mechanism 17 disposed inside the force application handle 18, and a constant force spring 16 is located between the piston 15 and the force adjustment mechanism 17. The force adjustment mechanism 17 is used to adjust the preload of the constant force spring 16.

[0044] like Figure 1 As shown, a return spring 19 is provided inside the force-applying handle 18 to apply an elastic force to the force-transmitting rack 3. When the tightening operation stops and the force on the force-applying handle 18 disappears, the return spring 19 pushes the force-transmitting rack 3 to drive the wrench head 1 to rotate around the second axis 2 in the opposite direction to the tightening operation. Since the one-way mechanism 10 is in the rotating state, the force-transmitting rack 3 is reset, and the wrench can perform the next tightening operation.

[0045] The working principle of the mechanical torque limiting wrench in this embodiment is as follows:

[0046] When tightening is performed, the upward force applied by the operator to the force application handle 18 causes the force transmission rack 3 to tend to rotate around the second shaft 2 in the first direction. Since the one-way mechanism 10 is locked, the reset gear 8 and the rotating mechanism 9 cannot rotate relative to each other. The force transmission rack 3 tends to drive the reduction gear set 5 and the unloading gear set 7 to rotate. Because the piston 15 presses the rolling element 11 under the spring force applied by the constant force spring 16, it prevents the reduction gear set 5, the unloading gear set 7, the reset gear 8 and the rotating mechanism 9 from rotating, so that the force transmission rack 3 cannot rotate around the second shaft 2. The force applied to the force application handle 18 drives the entire wrench to rotate through the second shaft 2, thus performing the tightening operation.

[0047] When the tightening force reaches the preset value, the rolling element 11 overcomes the spring force of the constant force spring 16 and pushes the piston 15 to move away from the first shaft 14, compressing the constant force spring 16. The rolling element 11 and the return gear 8 rotate in the second direction, while the unloading gear set 7 rotates in the first direction. When the tooth gap of the second large gear of the unloading gear set 7 is opposite to the return gear 8, the unloading gear set 7 disengages from the return gear 8. The unloading gear set 7 cannot drive the return gear 8 to rotate, and the force transmission rack 3 and the force reduction gear set 5 rotate rapidly, thus releasing the force of the wrench.

[0048] When the tightening operation stops and the force acting on the force application handle 18 disappears, the force transmission rack 3 rotates and resets around the second shaft 2 in the second direction under the action of the return spring 19. At the same time, it drives the reducing gear set 5 to rotate, the unloading gear set 7 rotates and resets, and the reset gear 8 can rotate freely around the shaft in the first direction (the free rotation direction of the one-way bearing). The reset gear 8 can rotate relative to the rotating mechanism 9, and the second large gear of the unloading gear set 7 re-engages with the reset gear 8. The piston 15 resets, preparing for the next tightening operation.

[0049] The first direction and the second direction are two opposite directions of rotation. For example, if the first direction is counterclockwise, then the second direction is clockwise.

[0050] The mechanical torque limiting wrench of this embodiment has the following advantages:

[0051] 1) The circular motion of the gears avoids the limitation of the rotation stroke by the hollow handle wall, allowing for a larger rotation angle of the handle when unloading force;

[0052] 2) The transmission between gears avoids the influence of friction on transmission accuracy;

[0053] 3) The gear moves in a circular motion and does not move along the axial direction of the handle, which reduces the spring compression stroke during unloading and improves the spring life;

[0054] 4) It avoids the impact of wear on the tilting block structure on the accuracy of the constant force;

[0055] 5) Gear transmission reduces force, lowers spring compression force, and improves spring fatigue life, which in turn improves product life.

[0056] Example 2

[0057] In this embodiment, at least two sets of reducing gear sets 5 are provided. The force transmission rack 3 meshes with the first pinion of the nearest reducing gear set 5, and the first large gear of the reducing gear set 5 meshes with the first pinion of the adjacent reducing gear set 5. The unloading gear set 7 meshes with the first large gear of the nearest reducing gear set 5, and the first pinion of the reducing gear set 5 meshes with the first large gear of the adjacent reducing gear set 5.

[0058] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution; or the direct application of the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A mechanical torque limiting wrench comprising a wrench head, a force applying handle, a piston, a constant force spring applying an elastic force to the piston, and a force reducing gear set arranged inside the force applying handle, characterized in that: The wrench head is connected with a force transmission rack, which is engaged with the force reduction gear set; a force release gear set is arranged inside the force applying handle and engaged with the force reduction gear set; a reset mechanism is arranged for disengaging the force release gear set when the wrench releases force; and a rolling element is arranged on the reset mechanism and in contact with the piston.

2. The mechanical torque wrench of claim 1, wherein: The force reduction gear set is arranged with at least one set.

3. The mechanical torque wrench of claim 1, wherein: The force reduction gear set comprises a first large gear and a first small gear arranged coaxially and rotating synchronously, the diameter of the first large gear being larger than that of the first small gear.

4. The mechanical torque wrench of claim 3, wherein: The force reduction gear set is arranged with one set, the first large gear is engaged with the force release gear set, and the first small gear is engaged with the force transmission rack.

5. The mechanical torque wrench of claim 3, wherein: The force reduction gear set is arranged with at least two sets, the force transmission rack is engaged with the first small gear of the nearest force reduction gear set, the first large gear of the force reduction gear set is engaged with the first small gear of the adjacent force reduction gear set; and the force release gear set is engaged with the first large gear of the nearest force reduction gear set, the first small gear of the force reduction gear set is engaged with the first large gear of the adjacent force reduction gear set.

6. The mechanical torque wrench of any one of claims 1 to 5, wherein: The force release gear set comprises a second large gear and a second small gear arranged coaxially and rotating synchronously, the diameter of the second large gear being larger than that of the second small gear.

7. The mechanical torque wrench of claim 6, wherein: The second large gear is engaged with the reset mechanism, and the first small gear is engaged with the force reduction gear set.

8. The mechanical torque wrench of claim 7, wherein: The second large gear is an incomplete gear, and the reset mechanism comprises a reset gear engaged with the second large gear.

9. The mechanical torque wrench of claim 8, wherein: The reset mechanism further comprises a rotating mechanism arranged coaxially with the reset gear and rotatable, the rolling element is arranged on the rotating mechanism, and a one-way mechanism is arranged in the rotating mechanism or the reset gear.

10. The mechanical torque wrench of any one of claims 1 to 5, wherein: A force adjustment mechanism is arranged inside the force applying handle, and the constant force spring is located between the piston and the force adjustment mechanism.

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