Built-in dynamic torque sensor and intelligent tightening tool

Abstract

The utility model relates to the field of auxiliary equipment for tightening screws, in particular to a built-in dynamic torque sensor and an intelligent tightening tool, which comprises a rotating piece with a deformation part and an electric brush, a resistance strain gauge is arranged on the deformation part; the rotating piece transmits torque to a resistance strain gauge on the deformation part in any rotating direction; the electric brush and the resistance strain gauge are conducted, the electric brush is used for transmitting a detection signal after resistance change to the processor, the built-in dynamic torque sensor can keep a power-on state during rotation and can directly measure the torque of an object during rotation, the function of considering the rotation of the object can be directly connected with the output shaft end of a driving source, and at the moment, the torque can be directly measured. Torque measured and calculated by the built-in dynamic torque sensor is real torque of the bit, and the bit has the advantage of being high in precision.

Description

Technical Field

[0001] The utility model relates to the field of auxiliary equipment for tightening screws, especially an intelligent tightening tool with a built-in dynamic torque sensor. Background Art

[0002] As a power-driven tool, it usually has a torque sensor inside. The torque sensor is used to measure the output torque when rotating or turning an object. Appropriate torque can ensure that the screw can achieve the expected tightening effect, so it will not be over-tightened and damaged.

[0003] Generally, the torque sensor in an electric screwdriver uses a resistance strain gauge. The resistance strain gauge can convert the change in strain on a mechanical component into a change in resistance, and then output a voltage, and obtain the torque through calculation. The technology of torque sensors using resistance strain gauges has basically matured.

[0004] The torque sensor has a first connection part, a deformation part, and a second connection part arranged in the following order. Usually, the motor shaft is connected to the first connection part through a flange. During rotation, due to the existence of torque, the deformation of the deformation part will cause a certain difference in the positions of the first connection part and the second connection part. At this time, the strain device on the deformation part can detect the torque of the motor shaft. However, the second connection part drives the bit through a speed reducer. Under this multi-stage transmission, a part of the force has been consumed. For example, part of the torque is consumed in the speed reducer. Obviously, the torque measured in this way has low accuracy and is far from the real data of the bit torque.

[0005] In addition, in the traditional structure of an electric screwdriver, when measuring torque, the torque of the bit is transmitted through multiple stages. For example, it needs to be transmitted through a speed reducer before reaching the strain device. Therefore, the problem of untimely detection of the bit torque leads to a certain delay in the control of the motor. That is to say, when the motor stops, the torque on the screw has exceeded the best tightening effect, resulting in low assembly accuracy or even unqualified situations. Summary of the Utility Model

[0006] To solve the above problems, the utility model provides an intelligent tightening tool with a built-in dynamic torque sensor. The built-in dynamic torque sensor in this electric screwdriver can directly calculate the torque of the bit and has the characteristics of high response and high accuracy.

[0007] To achieve the above purpose, the technical solution adopted by the utility model is:

[0008] An internal dynamic torque sensor, characterized in that it comprises: a rotating member with a deformation part and a brush; a resistance strain gauge is arranged on the deformation part; the rotating member transmits torque to the resistance strain gauge on the deformation part in any rotation direction; the brush is electrically connected to the resistance strain gauge, and the brush is used to transmit the detection signal after the resistance value changes to a processor.

[0009] Further, the brush comprises a first conductor and a conductive slip ring. An insulating sleeve is assembled on the rotating member, and the conductive slip ring is sleeved on the insulating sleeve; the conductive slip ring is electrically connected to the resistance strain gauge, and the first conductor is a stationary component, and the current is transmitted to the resistance strain gauge by leaning on the conductive slip ring.

[0010] Further, the leaning is that the first conductor is tangential to the outer ring surface of the conductive slip ring.

[0011] Further, at least two conductive slip rings are provided, which are respectively electrically connected to the input end and the output end of the resistance strain gauge, and are arranged on the insulating sleeve in sequence with a gap therebetween. An isolation ring is provided between the conductive slip rings for filling the above gap. The diameter of the isolation ring is larger than the diameter of the conductive slip ring, so that the first conductor leaning on the conductive slip ring is constrained by the adjacent isolation rings and is positioned on the conductive slip ring.

[0012] Further, it further comprises a grounding brush ring, which is sleeved on the rotating member and is electrically connected to the second conductor of the brush.

[0013] Further, it further comprises a sleeve. The rotating member rotates freely in the sleeve. A fixing frame is arranged in the sleeve, and the first conductor is assembled on the fixing frame to form a stationary component.

[0014] Further, the rotating member has an input end connected to a driving source and an output end connected to a bit. The brush is arranged on the input end, and the deformation part is arranged between the input end and the output end.

[0015] Further, the first conductor and the second conductor are brush wires.

[0016] An intelligent tightening tool comprises an output shaft end and a driving source that provides power to the bit, and further comprises the above-mentioned internal dynamic torque sensor. The internal dynamic torque sensor is arranged between the output shaft end and the bit, and is used to transmit the torque of the output shaft end to the bit and simultaneously detect the torque on the bit.

[0017] Further, the internal dynamic torque sensor has an input end and an output end, and a deformation part arranged between the input end and the output end; the brush is arranged on the input end; the input end is connected to the output shaft end of the driving source, and the output end is connected to the bit.

[0018] The beneficial effects of the present utility model:

[0019] 1. The built-in dynamic torque sensor of the present utility model can maintain a powered-on state during rotation and can directly measure the torque when an object rotates. This function that takes into account the rotation of the object can be directly connected to the output shaft end of the drive source in the field of electric screwdrivers. At this time, the torque measured by the built-in dynamic torque sensor is the true torque of the bit, featuring high precision.

[0020] 2. This built-in dynamic torque sensor is connected to the output shaft end of the drive source. This implementation method of directly collecting the torque of the bit can improve the response speed of the electric screwdriver and can timely adjust the drive source to ensure the best tightening effect for the screw.

[0021] 3. The present utility model uses a brush structure for wired connection. Compared with the wireless transmission connection method, the wired connection has stronger anti-interference ability, more stable transmission of detection signals, faster response, no delay, and more accurate measured torque. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a perspective view of the electric screwdriver.

[0023] Figure 2 is Figure 1 a perspective view of the interior.

[0024] Figure 3 is a perspective view of the built-in dynamic torque sensor.

[0025] Figure 4 is Figure 3 an exploded schematic view of

[0026] Figure 5 is a distribution schematic view of the conductive slip ring and the grounding brush ring.

[0027] Figure 6 is the front view after the conductive slip ring, the grounding brush ring and the conductor are connected.

[0028] Figure 7 is Figure 6 a perspective view of

[0029] Figure 8 is a perspective view of the built-in dynamic torque sensor.

[0030] Figure 9 is Figure 8 an enlarged schematic view of part A of

[0031] Figure 10 is a perspective view of the reducer.

[0032] Figure 11 is Figure 10 an exploded view of

[0033] Figure 12 is Figure 2 a partial sectional view of...

[0034] Figure 13 is a Wheatstone bridge circuit diagram. Specific embodiments

[0035] Figure 1 is a perspective view of the intelligent tightening tool being an electric screwdriver.

[0036] Figure 2 is an exploded view of the intelligent tightening tool being an electric screwdriver, combined with Figure 1 、 Figure 2 and Figure 12 , the electric screwdriver is composed of the following parts:

[0037] a housing 1 and a motor 2, a speed reducer 3, an internal dynamic torque sensor 4 located inside the housing 1, and a bit 5.

[0038] The motor 2 and the speed reducer 3 form a drive source. The internal dynamic torque sensor 4 is sleeved on the output shaft end of the drive source. The output end of the internal dynamic torque sensor 4 is connected to the bit 5 to measure the torque on the output shaft end, which is equal to the current torque of the bit 5.

[0039] As Figures 3 - 4 shown, the internal dynamic torque sensor 4 is composed of an inner cylinder 400, a resistance strain gauge (not shown in the figure), a brush 401, and a sleeve 402. The inner cylinder 400 and the sleeve 402 have a coincident central axis. The inner cylinder 400 is a rotating part. The inner cylinder 400 is arranged inside the sleeve 402 and rotates inside the sleeve 402 by means of bearings 403 provided at both ends. A partial area on the inner cylinder 400 is a deformation part A - 400. The resistance strain gauge is attached to the deformation part A - 400. When the inner cylinder 400 rotates, due to the existence of a reaction force, the deformation part A - 400 will deform. For the resistance strain gauge attached to the deformation part A - 400, it will also change its shape accordingly with the deformation of the deformation part A - 400. At this time, the resistance value in the resistance strain gauge is related to the cross-sectional area. When the cross-sectional area changes, the current passing through the resistance strain gauge also changes. The processor obtains the current torque of the bit 5 based on this change;

[0040] The brush 401 is used to conduct and connect with the resistance strain gauge when the inner cylinder 400 rotates, and the detected signal after the resistance value changes reaches the control board (not shown in the figure) that controls the rotation of the motor 2.

[0041] Traditional bit torque detection, such as the structure shown in Patent 202410011024.0, is a static detection method that utilizes the reaction force generated by the motor to provide torque. The torque transmission path obtained by the built-in dynamic torque sensor is: bit - reducer - built-in dynamic torque sensor. Since the torque is transmitted through the reducer, torque loss occurs, and the longer transmission path also requires more time, resulting in slower detection accuracy of the torque magnitude and detection timeliness.

[0042] Since the detected torque is directly transmitted from the bit 5 to the built-in dynamic torque sensor.

[0043] In terms of the structure of this embodiment, the brush 401 can provide current to the strain gauge in the rotating state. For a continuously rotating component like the bit 5, this built-in dynamic torque sensor 4 perfectly fits the usage scenario of detecting this type of bit 5, directly detecting the torque of the bit 5, with higher detection accuracy. At the same time, the solution of directly detecting the torque of the bit 5 can effectively improve the response speed of the control of the motor 2 (the control board can timely stop the power output of the motor 2 to the bit 5).

[0044] The brush 401 includes a first conductor 401a and a conductive slip ring 401b. An insulating sleeve 404 is sleeved on the inner cylinder 400, and the conductive slip ring 401b is sleeved on the insulating sleeve 404 and conducts with the strain gauge. The first conductor 401a is a stationary component. After leaning on the conductive slip ring 401b, it transmits current to the strain gauge. The contact between the first conductor 401a and the conductive slip ring 401b enables the conductive slip ring 401b to maintain the output from the strain gauge to the control board even when it rotates following the inner cylinder 400. The structure is simple and highly practical (the processor is set on the control board).

[0045] Generally, the connection relationship between the brush 401 and the conductive slip ring 401b is that the brush 401 is tangential to the outer ring surface of the conductive slip ring 401b, which is beneficial to increasing the contact area between the brush 401 and the conductive slip ring 401b and strengthening the stability of conduction.

[0046] In the embodiment, there are two strain gauges, and correspondingly, four conductive slip rings 401b are provided. Any two conductive slip rings 401b correspond to the positive and negative poles of one strain gauge, and the other two conductive slip rings 401b correspond to the positive and negative poles of the other strain gauge. Of course, there is also a grounding brush ring 405, which is sleeved on the inner cylinder 400 and conducts with the second conductor 401c in the brush 401 (as Figures 6 - 9 shown), and the grounding brush ring is electrically connected to the bit 5 for receiving the static electricity transmission on the bit 5 and transmitting the static electricity to the grounding wire.

[0047] In a preferred embodiment, specifically, in this embodiment, 4 resistance strain gauges are provided in the deformation part A-400, preferably evenly distributed on the deformation part A-400; as Figure 13 shown in the Wheatstone bridge circuit, the 4 resistance strain gauges in this embodiment are connected in the circuit shown in Figure 13 . Specifically, the 4 resistance strain gauges correspond to R1, R2, R3, and R4 respectively. Figure 13 The corresponding connection points ABCD in Figure 13 are respectively connected to the conductive slip rings 401b in the brush 401; as shown in y , the bridge supply voltage input at the AC point is U0, and the output voltage of the bridge is U Y = U0(R1R3 - R2R4) / ((R1 + R2)(R3 + R4)), and based on the resistance change value and the calibrated torque or the calibrated standard curve, the required detected torque is obtained; as a preferred implementation method, 4 resistance strain gauges with the same initial resistance value are provided in this embodiment. The characteristic of the resistance strain type sensor is that the resistance value of the resistance strain gauge changes with the strain of the elastic body, but the change amount of this resistance value is very small and difficult to directly detect. Therefore, in this embodiment, using the Wheatstone bridge to indirectly measure the resistance value change of the resistance strain gauge will be more accurate.

[0048] As shown in Figure 5 , further, the conductive slip rings 401b are distributed in an intermittent manner, and an isolation ring 406 for filling the above gap is provided between the conductive slip rings 401b. This is to avoid the occurrence of a short circuit. In addition, the diameter of the isolation ring 406 is larger than the diameter of the conductive slip ring 401b, so that a slip ring groove is formed between two adjacent conductive slip rings 401b. In this way, the first conductor 401a resting on the conductive slip ring 401b will be restricted by the adjacent isolation ring 406 and positioned on one of the conductive slip rings 401b. Under this design, it is beneficial to the use safety.

[0049] The first conductor 401a and the second conductor 401c are inclined and shoot outwards. A fixing frame 407 is provided in the sleeve 402. After the first conductor 401a and the second conductor 401c are connected inside the sleeve 402, the first conductor 401a and the second conductor 401c form stationary components.

[0050] The above-mentioned conductors are all brush wires, and wear-resistant conductive coatings are applied on the surfaces of the brush wires, the conductive slip rings 401b, and the grounding brush ring 405, thereby improving the service life of the brush.

[0051] It should be noted that the built-in dynamic torque sensor of the present utility model has an input end and an output end. Specifically, the input end and the output end are the two ends of the inner cylinder 400. The deformation part A-400 is located between the input end and the output end. The conductive slip ring 401b is sleeved on the input end. The purpose of this design is to make the detected torque not include the torque generated by the friction between the conductor and the conductive slip ring 401b and the grounding brush ring 405, thereby improving the detection accuracy.

[0052] It should also be noted that the inner cylinder 400, which serves as the input end and the output end of the built-in dynamic torque sensor, is detachably connected to the speed reducer 4 and the bit 5. The inner cylinder 400 is sleeved on the output shaft end of the speed reducer 4. The outer end of the inner cylinder 400 has a triangular opening that is adapted to the triangular shape at the inner end of the bit 5. After the bit 5 passes through the opening, due to the shape constraint, the bit 5 rotates following the inner cylinder 400. At the same time, the inner cylinder 400 is arranged in the sleeve 402 through the bearing 403, and the brush wire is fixed in the sleeve 402 through the fixing bracket 407. In this setting mode, the built-in dynamic torque sensor can be separated from the bit 5 and the speed reducer 4 integrally, which is conducive to conveniently and quickly replacing the damaged built-in dynamic torque sensor alone, thereby reducing the usage cost.

[0053] As Figures 10 - 11 shown, the speed reducer 3 includes a planetary gear set 31 and an output main shaft 33. The planetary gear set 31 has two layers. The output main shaft 33 is connected to one of the planetary gear sets 31. The teeth 32' on the inner ring surface of the rotating shell 32 mesh with the two layers of planetary gear sets 31. Any one of the planetary gear sets 31 drives the rotating shell 32 to rotate, and the rotating shell 32 will drive the other layer of planetary gear set 31 to rotate. Since the planetary gear set 31 is a prior art, its specific structure will not be described in detail here.

[0054] The driving source formed by combining the motor 2 and the speed reducer 3 is one of the implementation modes and does not further limit the driving source. In another implementation, the driving source is a pneumatic motor. Of course, the driving source can also be other implementation modes.

[0055] The above implementation modes only describe the preferred implementation modes of the present utility model and do not limit the scope of the present utility model. Without departing from the design spirit of the present utility model, various deformations and improvements made by those of ordinary engineering and technical personnel in the art to the technical solutions of the present utility model should fall within the protection scope determined by the claims of the present utility model.

Claims

1. An internal dynamic torque sensor, characterized in that, It includes: a rotating part with a deformation part and a brush; a resistance strain gauge is arranged on the deformation part; the rotating part transmits torque to the resistance strain gauge on the deformation part in any rotation direction; the brush is electrically connected to the resistance strain gauge, and the brush is used to transmit the detection signal after the resistance value changes to the processor.

2. The built-in dynamic torque sensor according to claim 1, characterized in that, The brush includes a first conductor and a conductive slip ring. An insulating sleeve is assembled on the rotating part, and the conductive slip ring is sleeved on the insulating sleeve; the conductive slip ring is electrically connected to the resistance strain gauge, and the first conductor is a stationary component, and the current is transmitted to the resistance strain gauge by leaning on the conductive slip ring.

3. The built-in dynamic torque sensor according to claim 2, characterized in that, The leaning is that the first conductor is tangential to the outer ring surface of the conductive slip ring.

4. The built-in dynamic torque sensor according to claim 2, characterized in that, There are at least two conductive slip rings, which are respectively electrically connected to the input end and the output end of the resistance strain gauge, and are arranged on the insulating sleeve in sequence with a gap. An isolation ring is arranged between the conductive slip rings to fill the above gap. The diameter of the isolation ring is larger than the diameter of the conductive slip ring, so that the first conductor leaning on the conductive slip ring is constrained by the adjacent isolation rings and is positioned on the conductive slip ring.

5. The built-in dynamic torque sensor according to claim 2, characterized in that, It also includes a grounding brush ring, which is sleeved on the rotating part and is electrically connected to the second conductor of the brush.

6. The built-in dynamic torque sensor according to claim 2, wherein It also includes a sleeve. The rotating part rotates freely in the sleeve. A fixing frame is arranged in the sleeve, and the first conductor is assembled on the fixing frame to form a stationary component.

7. The built-in dynamic torque sensor according to claim 1, wherein The rotating part has an input end connected to the drive source and an output end connected to the bit. The brush is arranged on the input end, and the deformation part is arranged between the input end and the output end.

8. A built-in dynamic torque sensor according to any one of claims 2-6, characterized in that, The first conductor and the second conductor are brush wires.

9. An intelligent tightening tool, comprising a driving source that provides power to a bit at the output shaft end, characterized in that, It also includes the built-in dynamic torque sensor according to any one of the above claims 1-8. The built-in dynamic torque sensor is arranged between the output shaft end and the bit, and is used to transmit the torque of the output shaft end to the bit and simultaneously detect the torque on the bit.

10. An intelligent tightening tool according to claim 9, characterized in that, The built-in dynamic torque sensor has an input end and an output end, and a deformation part arranged between the input end and the output end; the brush is arranged on the input end; the input end is connected to the output shaft end of the drive source, and the output end is connected to the bit.

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