CN110238800B

CN110238800B - Electric tool and torsion detecting device thereof

Info

Publication number: CN110238800B
Application number: CN201810193655.3A
Authority: CN
Inventors: 梁智翔
Original assignee: Mobiletron Electronics Co Ltd
Current assignee: Mobiletron Electronics Co Ltd
Priority date: 2018-03-09
Filing date: 2018-03-09
Publication date: 2022-04-05
Anticipated expiration: 2038-03-09
Also published as: CN110238800A

Abstract

A power tool, comprising: the device comprises a shell, and a motor, a transmission device, a torsion detection device and a control device which are arranged in the shell, wherein the shell is provided with a first positioning part; the transmission device comprises a rotating part for the tool head to be arranged, and the rotating part rotates along with the rotating shaft of the motor; the torsion detecting device comprises a planetary gear set, a fixed piece and a torsion detecting component, wherein the planetary gear set is arranged on the rotating piece, the fixed piece is sleeved on the planetary gear set, an inner gear ring of the fixed piece is meshed with the planetary gear, and the fixed piece is abutted against the shell and does not rotate along with the rotating piece. The torsion sensing assembly is arranged on the fixing piece. The control device controls the rotating shaft of the motor to stop rotating according to the sensing result of the torque sensing assembly. Therefore, the torsion can be accurately controlled.

Description

Electric tool and torsion detecting device thereof

Technical Field

The present invention relates to an electric tool, and more particularly to an electric tool with torque control function and a torque detection device thereof.

Background

The electric tool in the prior art, such as an electric screwdriver and an electric wrench, includes a control device, a motor, a transmission device and a torque detection device, wherein the control device is electrically connected to the motor and the torque detection device, a rotating shaft of the motor is connected to the transmission device, and a rotating shaft of the transmission device is provided for mounting a tool head. The torque force detecting device is arranged between the motor and the transmission device and is used for detecting the torque force between the rotating shaft of the motor and the transmission device. The control device controls the motor to stop rotating when the torque detected by the torque detecting device reaches a predetermined torque.

Although the torque control of the electric tool in the prior art can be achieved, the detected torque is the torque between the rotating shaft of the motor and the transmission device, and is still a distance away from the rotating shaft of the tool head, so that the error between the torque detected by the torque detection device and the torque actually applied to the rotating shaft still exists, and the torque actually output by the electric tool is inaccurate.

Disclosure of Invention

Accordingly, the present invention is directed to an electric tool and a torque detecting device thereof, which can achieve precise torque control.

In order to achieve the above object, the present invention provides a power tool for connecting a tool bit, comprising: the device comprises a shell, a motor, a transmission device, a torsion detection device and a control device, wherein the shell is provided with a first positioning part; the motor is arranged in the shell; the transmission device is arranged in the shell and connected with the rotating shaft of the motor, the transmission device comprises a rotating part for the tool head to be arranged, and the rotating part rotates along a preset axis along with the rotation of the rotating shaft of the motor; the torque force detecting device is arranged in the shell and comprises a planetary gear set, a fixed piece and a torque force sensing assembly, wherein the planetary gear set is arranged on the rotating piece, and the planetary gear set comprises a plurality of planetary gears which are driven by the rotating piece to move around the preset axis; the fixed piece is sleeved on the planetary gear set, the fixed piece is provided with an inner gear ring which is meshed with the planetary gear, and the fixed piece is also provided with a second positioning part which is abutted against the first positioning part of the shell so as to limit the fixed piece not to rotate along with the rotating piece; the torsion sensing assembly is arranged on the fixing piece and used for sensing torsion borne by the fixing piece; the control device is electrically connected with the torque sensing assembly and the motor, and controls the rotating shaft of the motor to stop rotating according to the sensing result of the torque sensing assembly.

The invention provides a torque force detection device of an electric tool, wherein the electric tool comprises a shell and a rotating piece positioned in the shell, and the shell is provided with a first positioning part; the torsion detecting device includes: the device comprises a planetary gear set, a fixed piece and a torque sensing assembly, wherein the planetary gear set is arranged on a rotating piece and comprises a plurality of planetary gears which are driven by the rotating piece to move around a preset axis; the fixed piece is sleeved on the planetary gear set, the fixed piece is provided with an inner gear ring which is meshed with the planetary gear, and the fixed piece is also provided with a second positioning part which is abutted against the first positioning part of the shell so as to limit the fixed piece not to rotate along with the rotating piece; the torsion sensing assembly is arranged on the fixing piece and used for sensing torsion borne by the fixing piece.

The torque force sensing component of the torque force sensing device indirectly senses the torque force applied to the rotating part, and the control device controls the rotating shaft of the motor to stop rotating according to the sensing result of the torque force sensing component, so that accurate torque force control is achieved.

Drawings

Fig. 1 is a partial perspective view of a power tool according to a first preferred embodiment of the present invention.

Fig. 2 is a partially exploded perspective view of the electric power tool of the preferred embodiment.

Fig. 3 is another partially exploded perspective view of the power tool of the preferred embodiment.

Fig. 4 is a partial sectional view of the electric power tool of the above preferred embodiment.

Fig. 5 is a sectional view taken in the direction of 5-5 of fig. 2.

FIG. 6 is a block diagram of the electrical connection of the control device according to the above preferred embodiment.

Fig. 7 is a schematic diagram illustrating a relationship between voltage and time corresponding to the torque detected by the torque detecting device according to the above preferred embodiment.

Fig. 8 is a partial perspective view of a power tool according to a second preferred embodiment of the present invention.

Fig. 9 is a partially exploded perspective view of the electric power tool of the above preferred embodiment.

Fig. 10 is a partial sectional view of the electric power tool of the above preferred embodiment.

Fig. 11 is a partial perspective view of a power tool according to a third preferred embodiment of the present invention.

Fig. 12 is a partially exploded perspective view of the electric power tool of the above preferred embodiment.

Fig. 13 is a partial sectional view of the electric power tool of the above preferred embodiment.

Fig. 14 is a schematic diagram illustrating a relationship between voltage and time corresponding to the torque detected by the torque detecting device according to the above preferred embodiment.

[ notation ] to show

100 electric tool

10 housing 102a first positioning portion of housing 102

12 motor 122 shaft 14 transmission device

16 reducer 18 rotating member 20 drive shaft

22 output shaft 24 clutch 242 first blocking wall

244 second blocking wall 246 ball 248 spring

26 third baffle 28 torsion detecting device 30 planetary gear set

302 planetary gear 32 fixed member 32a internal gear ring

32b second locator portion 34 retaining ring 342 first ring segment

344 second ring segment 344a recess 36 liner

362 engaging slot 362a boss 38 torque sensing assembly

40 control device 42 activation switch

200 electric tool

44 rotating member 46 drive shaft 48 output shaft

50 Clutch 502 first blocking wall 504 second blocking wall

52 torsion detecting device 54 planetary gear set 542 baffle plate

542a hexagonal hole 544 planetary gear 56 fixture

58 bushing 582 incorporates the trough 582a recess

60 second ring segment 602a projection of retaining ring 602

300 electric tool

62 rotating member 64 drive shaft 66 output shaft

68 planetary gear set

V predetermined voltage

Detailed Description

In order that the invention may be more clearly described, preferred embodiments will now be described in detail with reference to the accompanying drawings. Referring to fig. 1 to 6, an electric tool 100 according to a first preferred embodiment of the present invention includes a housing 10, a motor 12, a transmission 14, a torque detection device 28 and a control device 40, wherein:

the housing 10 is formed by combining two housings 102 (only one housing is shown in fig. 1), the housing 10 has at least one first positioning portion 102a, in this embodiment, the two housings 102 each have a first positioning portion 102a, and the first positioning portion 102a is a positioning column.

The motor 12 is disposed in the housing 10. The transmission 14 is disposed in the housing 10 and connected to the rotating shaft 122 of the motor 12, the transmission 14 includes a speed reducer 16 and a rotating member 18, in this embodiment, the speed reducer 16 is a planetary speed reducer; the rotating member 18 is connected to a power output shaft (not shown) of the speed reducer 16, and the rotating member 18 rotates along a predetermined axis with the rotation of the rotating shaft 122 of the motor 12. One end of the rotatable member 18 is provided for mounting a tool bit (not shown).

In this embodiment, the rotating member 18 includes a transmission shaft 20, an output shaft 22 and a clutch 24 disposed between the transmission shaft 20 and the output shaft 22, wherein one end of the transmission shaft 20 is connected to the speed reducer 16, and the transmission shaft 20 drives the output shaft 22 to rotate through the clutch 24. The output shaft 22 is for mounting a tool bit. More specifically, the clutch 24 includes a first blocking wall 242, a second blocking wall 244 and a plurality of balls 246 disposed between the two

blocking walls

242, 244, and a spring 248, wherein the first blocking wall 242 is connected to the output shaft 22, the second blocking wall 244 is connected to the transmission shaft 20, and the spring 248 is sleeved on the transmission shaft 20 and pushes the second blocking wall 244 toward the first blocking wall 242. In addition, the output shaft 22 is further provided with a third blocking wall 26, and the third blocking wall 26 is separated from the first blocking wall 242 by a distance.

The torque detecting device 28 is disposed in the housing 10 and includes a planetary gear set 30, a fixed member 32 and a torque sensing element 38, wherein the planetary gear set 30 is disposed on the rotating member 18, and more specifically, the planetary gear set 30 is connected to the clutch 24. The planetary gear set 30 includes a plurality of planetary gears 302 driven by the rotating member 18 to move around the predetermined axis. In this embodiment, the planetary gear 302 is pivoted to the first blocking wall 242, and the position of the planetary gear 302 is limited by the third blocking wall 26 to prevent the planetary gear 302 from being disengaged. In practice, the third blocking wall 26 may not be provided, and only a limiting part is provided on the pivot of the planetary gear 302 to prevent the planetary gear 302 from separating.

The fixed member 32 is sleeved on the planetary gear set 30, the fixed member 32 has an inner ring gear 32a engaged with the planetary gear 302, and the fixed member 32 further has at least one second positioning portion 32b abutting against the first positioning portion 102a of the housing 10 to limit the fixed member 32 from rotating with the rotating member 18. In this embodiment, the fixing element 32 includes a positioning ring 34 and a bushing 36, two opposite positions of the positioning ring 34 respectively have a second positioning portion 32b, and the second positioning portion 32b is a positioning hole, for example, for a positioning column of the first positioning portion 102a to penetrate. The bushing 36 has the inner ring 32a, and the retaining ring 34 is coupled to one end of the bushing 36. More specifically, one end of the bushing 36 is recessed to form a coupling groove 362, and the positioning ring 34 is coupled to the coupling groove 362. The wall surface of the coupling groove 362 has a plurality of projections 362 a; the positioning ring 34 includes a first ring segment 342 and a second ring segment 344 that are divided into an inner side and an outer side and connected to each other, the first ring segment 342 has the second positioning portion 32b on the outer periphery thereof, and the second ring segment 344 has a plurality of concave portions 344a on the outer periphery thereof. The second ring segment 344 is located in the coupling groove 362, and the convex portion 362a of the coupling groove 362 extends into the concave portion 344a of the second ring segment 344.

The torque sensing assembly 38 is disposed on the fixing member 32, and is configured to sense a torque applied to the fixing member 32 and output a corresponding voltage. In the embodiment, the torque sensing element 38 is a strain gauge, and the torque sensing element 38 is disposed on the positioning ring 34, more specifically, on a surface of the first ring segment 342 opposite to the groove surface of the engaging groove 362. In practice, the torque sensing assembly 38 may also be disposed on the bushing 36, such as on the groove surface of the engaging groove 362. The securing member 32 may also be of unitary design.

The control device 40 is electrically connected to the torque sensing assembly 38 and the motor 12, and the control device 40 controls the rotating shaft 122 of the motor 12 to stop rotating according to the sensing result of the torque sensing assembly 38. In this embodiment, the control device 40 is further electrically connected to a start switch 42, and when the start switch 42 is activated, the control device 40 controls the rotating shaft 122 of the motor 12 to rotate, so as to drive the rotating member 18 to rotate through the speed reducer 16. Referring to fig. 5, since the fixed member 32 is stationary relative to the housing 10 and the planetary gear 302 moves around the inner ring gear 32a of the fixed member 32, when the rotating member 18 rotates smoothly, the torque sensing assembly 38 can sense the torque applied to the fixed member 32 and output a corresponding voltage, i.e., indirectly sense the torque of the rotating member. Referring to fig. 7, waveforms of voltage changes corresponding to the torque sensed by the torque sensing component 38 during the process of increasing the torque on the rotating member 18 to the clutch 24 to generate the clutching are shown. From the above voltage variation, a predetermined voltage V can be set in the control device 40, and when the control device 40 determines that the voltage output by the torque sensing element 38 reaches the predetermined voltage V (corresponding to the torque reaching a predetermined torque), the control device controls the rotating shaft 122 of the motor 12 to stop rotating, and then the voltage output by the torque sensing element 38 may rise to a peak value due to the inertia of the rotating element 18 until the voltage drops after the clutch 24 is disengaged. Therefore, the control device 40 can achieve accurate torque control. The clutch 24 is used as a buffer, and is not easy to generate vibration when the rotation shaft 122 stops rotating, so that a user can obtain a better hand feeling when holding the electric power tool 100.

Fig. 8 to 10 show an electric tool 200 (not shown) according to a second preferred embodiment of the present invention, which has a structure substantially the same as that of the first embodiment, wherein the rotating member 44 also includes a transmission shaft 46, an output shaft 48 and a clutch 50 disposed between the transmission shaft 46 and the output shaft 48, and the clutch 50 also has a first blocking wall 502, a second blocking wall 504 and a plurality of balls (not shown) disposed between the two blocking

walls

502, 504. In contrast, the planetary gear set 54 of the torque detection device 52 of the present embodiment is disposed on the transmission shaft 46. The planetary gear set 54 includes two baffles 542, the two baffles 542 are disposed on the transmission shaft 46, and the planetary gear 544 is pivotally disposed between the two baffles 542. More specifically, the two blocking plates 542 each have a non-circular hole, such as a hexagonal hole 542a, the hexagonal hole 542a is through which the transmission shaft 46 passes, and the transmission shaft 46 has a hexagonal outer peripheral shape matching the hexagonal hole 542 a.

In addition, the slot wall of the engaging slot 582 of the bushing 58 of the fixing member of the torque detecting device 52 has a plurality of recesses 582a, and the second ring segment 602 of the positioning ring 60 has a plurality of protrusions 602a to fit into the recesses 582 a.

When the rotating member 44 rotates, the control device 40 controls the rotating shaft 122 of the motor 12 to stop rotating when the voltage corresponding to the torque force sensed by the torque force sensing assembly 38 reaches the predetermined voltage V (i.e. the torque force reaches the predetermined torque force). Thereby, also an accurate torque control can be achieved.

Fig. 11 to 13 show an electric power tool 300 (not shown) according to a third preferred embodiment of the present invention, which has substantially the same structure as the second embodiment, except that no clutch is provided between the transmission shaft 64 and the output shaft 66 of the rotating member 62, and the planetary gear set 68 is provided on the transmission shaft 64. In this embodiment, the transmission shaft 64 is integrally connected to the output shaft 66. In fact, the transmission shaft 64 and the output shaft 66 may be detachably connected, for example, they are connected in a matching manner; or one with a convex part and the other with a corresponding concave part. Of course, the transmission shaft 64 and the output shaft 66 may be indirectly connected, such as through a sleeve or coupling.

Referring to fig. 14, in the present embodiment, when the rotating member 62 rotates smoothly, the torque sensing assembly 38 can sense the torque applied to the fixing member 56 and output a corresponding voltage. When the torque of the rotating member 62 increases, so that the voltage corresponding to the torque sensed by the torque sensing element 38 reaches the predetermined voltage V (i.e. the torque reaches the predetermined torque), the control device 40 controls the rotating shaft 122 of the motor 12 to stop rotating under the condition, and then the voltage output by the torque sensing element 38 decreases.

Accordingly, the electric tool of the invention can detect the voltage corresponding to the torque output of the rotating part through the torque sensing component of the torque detecting device, and the control device controls the rotating shaft of the motor to stop rotating according to the sensing result of the torque sensing component, thereby achieving accurate torque control.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A power tool for connection to a tool bit, comprising:

a housing having a first positioning portion;

a motor disposed in the housing;

the transmission device is arranged in the shell and connected with the rotating shaft of the motor, the transmission device comprises a rotating part for the tool head to be arranged, and the rotating part rotates along a preset axis along with the rotation of the rotating shaft of the motor;

a torque detecting device disposed in the housing and including a planetary gear set, a fixed member and a torque sensing assembly, wherein the planetary gear set is disposed on the rotating member, and the planetary gear set includes a plurality of planetary gears driven by the rotating member to move around the predetermined axis; the fixed part is sleeved on the planetary gear set, the fixed part is provided with an inner gear ring meshed with the planetary gear, the fixed part is also provided with a second positioning part abutted against the first positioning part of the shell so as to limit the fixed part not to rotate along with the rotating part, the fixed part comprises a positioning ring and a lining, the inner side and the outer side of the positioning ring are divided into a first ring section and a second ring section, the first ring section of the positioning ring is provided with the second positioning part, the lining is provided with the inner gear ring, and the second ring section of the positioning ring is combined at one end of the lining; the torsion sensing assembly is arranged on one surface of the first ring segment of the positioning ring, which faces the lining, and is used for sensing torsion borne by the fixing piece; and

and the control device is electrically connected with the torque sensing assembly and the motor and controls the rotating shaft of the motor to stop rotating according to the sensing result of the torque sensing assembly.

2. The power tool of claim 1, wherein an end of the bushing is recessed to form a coupling groove, and the positioning ring is disposed in the coupling groove.

3. The power tool of claim 1, wherein the rotating member includes a transmission shaft, an output shaft, and a clutch disposed between the transmission shaft and the output shaft, the transmission shaft driving the output shaft to rotate through the clutch; the output shaft is provided for installation; the planetary gear set is connected with the clutch.

4. The power tool as claimed in claim 3, wherein the clutch comprises a first blocking wall and a second blocking wall, and a plurality of balls are disposed between the first blocking wall and the second blocking wall, wherein the first blocking wall is connected to the output shaft, and the second blocking wall is connected to the transmission shaft; the planet gear is pivoted on the first blocking wall.

5. The electric tool according to claim 3, wherein the control device controls the rotation shaft of the motor to stop rotating when the voltage corresponding to the torque sensed by the torque sensing assembly reaches a predetermined voltage.

6. The power tool of claim 1, wherein the rotating member includes a transmission shaft, an output shaft, and a clutch disposed between the transmission shaft and the output shaft, the transmission shaft driving the output shaft to rotate through the clutch; the output shaft is provided for installation; the planetary gear set is arranged on the transmission shaft.

7. The power tool of claim 6, wherein the planetary gear set comprises two baffles, the two baffles are disposed on the transmission shaft, and the planetary gear is pivotally disposed between the two baffles.

8. The power tool of claim 6, wherein the control device controls the rotation shaft of the motor to stop rotating when the voltage corresponding to the torque sensed by the torque sensing assembly reaches a predetermined voltage.

9. The power tool of claim 1, wherein the rotatable member includes a drive shaft and an output shaft connected, the drive shaft rotating the output shaft; the output shaft is provided for installation; the planetary gear set is arranged on the transmission shaft.

10. The power tool of claim 9, wherein the planetary gear set comprises two baffles, the two baffles are disposed on the transmission shaft, and the planetary gear is pivotally disposed between the two baffles.

11. The electric tool according to claim 9, wherein the control device controls the rotation shaft of the motor to stop rotating when the voltage corresponding to the torque sensed by the torque sensing assembly reaches a predetermined voltage.

12. A torque force detection device of an electric tool comprises a shell and a rotating piece, wherein the shell is provided with a first positioning part; the torsion detecting device includes:

the planetary gear set is arranged on the rotating piece and comprises a plurality of planetary gears which are driven by the rotating piece to move around a preset axis;

the fixing piece is sleeved on the planetary gear set and provided with an inner toothed ring meshed with the planetary gear, the fixing piece is also provided with a second positioning part abutted against the first positioning part of the shell so as to limit the fixing piece not to rotate along with the rotating piece, the fixing piece comprises a positioning ring and a lining, the inner side and the outer side of the positioning ring are divided into a first ring section and a second ring section, the first ring section of the positioning ring is provided with the second positioning part, the lining is provided with the inner toothed ring, and the second ring section of the positioning ring is combined at one end of the lining;

and the torsion sensing assembly is arranged on one surface of the first ring segment of the positioning ring, which faces the lining, and is used for sensing the torsion borne by the fixing piece.

13. The torque detecting device of an electric tool according to claim 12, wherein an end of the bushing is recessed to form a coupling groove, and the positioning ring is disposed in the coupling groove.

14. The torque detecting device of an electric tool according to claim 12, wherein the planetary gear set includes two baffles, the two baffles are used for the transmission shaft to pass through, and the planetary gear is pivotally disposed between the two baffles.