CN216299136U - Electric screwdriver - Google Patents

Abstract

The utility model discloses an electric screwdriver which comprises a striking shaft, a motor, a planetary speed reducing mechanism and a torque monitoring mechanism, wherein the striking shaft is connected with the motor through a screw; one end of the transmission shaft is clamped and tightly matched with an output shaft of the motor, and the other end of the transmission shaft is provided with a gear part which is internally meshed with and fixed with a sun gear of the planetary reduction mechanism; the torque monitoring mechanism comprises a driving shaft, a clutch sleeve, a steel ball and a displacement detector; the clutch sleeve, the clutch end I of the striking shaft and the clutch end II of the driving shaft are sleeved in sequence from outside to inside; the clutch end I is provided with a steel ball channel; the clutch end II is provided with a convex part; when the bulge part is aligned with the steel ball channel, the circular truncated cone-shaped inner wall of the clutch sleeve is extruded outwards along the radial direction, so that the clutch sleeve generates displacement along the axial direction, thereby realizing the purpose of converting the torque change of the electric screwdriver into the displacement change of the clutch sleeve, automatically controlling the motor according to the monitoring result and realizing the torque-fixing control. The transmission shaft, the motor and the planetary reduction mechanism are integrally assembled, low-speed high-torque output is met, motion transmission precision is improved, and fixed-torque control is facilitated.

Description

Electric screwdriver

Technical Field

The utility model relates to the field of electric tools, in particular to an electric screwdriver.

Background

The electric screwdriver is an electric tool which can convert kinetic energy generated by the rotation of an electric motor into deformation energy of a thread connecting piece in the outside, is used for screwing and disassembling the thread connecting piece, and can be widely applied to industries such as household appliances, automobiles, motorcycles and the like.

In order to ensure the assembly quality of the product, an operator often needs to enable the electric screwdriver to complete the installation of the internal thread connecting piece of the product with a specific torque, in other words, the electric screwdriver with the torque fixing function can ensure the installation effect of the internal thread connecting piece of the product, and further ensure the assembly quality of the product.

However, in the conventional electric screw drivers, part of the electric screw drivers cannot realize fixed-torque operation due to the limitation of functional principles; although some electric screwdrivers can realize fixed torque, the torque transmission precision and the detection precision are relatively low, so the fixed torque control effect of the electric screwdrivers is general, and the torque actually processed by the tool on the threaded coupling part has a large error with the expected torque of an operator, which not only affects the assembly quality of the product and the threaded coupling part thereof, but also is not beneficial to the service life of the electric screwdrivers and the operation safety.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide an electric screwdriver which can realize torque fixing operation with high torque transmission precision and torque detection precision.

In order to achieve the purpose, the utility model provides an electric screwdriver which comprises a shell, a striking shaft and a motor, a planetary speed reducing mechanism, a transmission shaft and a torque monitoring mechanism, wherein the striking shaft and the motor are arranged in the shell; one end of the transmission shaft is clamped and tightly matched with an output shaft of the motor, and the other end of the transmission shaft is provided with a gear part which is internally meshed with and fixed on a sun gear of the planetary reduction mechanism; the torque monitoring mechanism comprises a driving shaft, a clutch sleeve, a steel ball and a displacement detector;

the circular truncated cone-shaped inner wall of the clutch sleeve, the clutch end I of the striking shaft and the clutch end II of the driving shaft are sequentially sleeved from outside to inside; a plurality of steel ball channels which are annularly distributed and are penetrated along the radial direction are arranged in the circumferential direction of the clutch end I; a plurality of annularly distributed and radially extending protrusions are arranged on the circumferential direction of the clutch end II; the number of the steel balls, the number of the steel ball channels and the number of the convex parts are equal; any one of the convex parts is in contact fit with the inner wall of the clutch end I when the working torque does not reach a set value I, and rotates and pushes the steel ball to move outwards along the steel ball channel to squeeze the circular truncated cone-shaped inner wall when the working torque reaches the set value I; and the displacement detector automatically shuts down the motor when the displacement of the clutch sleeve reaches a set value II.

Preferably, the planetary reduction mechanism includes the sun gear, the planet gear, and a reducer housing; the sun wheel and the planet wheel are positioned and installed in the speed reducer shell; the surface of the speed reducer casing is provided with a mounting hole for the gear part to penetrate.

Preferably, the striking shaft, the driving shaft and the output shaft of the motor are connected in sequence; the small-diameter end of the circular truncated cone-shaped inner wall faces the striking shaft.

Preferably, the device further comprises a reference block arranged on the striking shaft and a spring I sleeved on the striking shaft; the reference block, the clutch sleeve and the motor are sequentially distributed along the axial direction of the striking shaft, and two axial ends of the spring I are respectively abutted to the clutch sleeve and the reference block.

Preferably, the torque monitoring mechanism further comprises a torque-fixing adjuster connected with the reference block and used for driving the reference block to move along the axial direction of the striking shaft.

Preferably, the casing is provided with a torque adjusting channel communicated to the torque fixing adjuster and a dust cover for shielding the torque adjusting channel.

Preferably, a retainer ring is sleeved on the periphery of the clutch end I, and the retainer ring slides along the axial direction of the striking shaft; ejector rods distributed in parallel are arranged on one side of the striking shaft; the clutch sleeve pushes the ejector rod to move along the axial direction of the ejector rod through the retainer ring; the displacement detector is arranged next to the ejector rod.

Preferably, the ejector rod is sleeved with a spring II; one axial end of the spring II is fixed relative to the shell, and the other axial end of the spring II is abutted against the stopper in the middle of the ejector rod; the displacement detector is specifically a proximity switch; the proximity switch is arranged at one end, far away from the spring II, of the ejector rod.

Preferably, a surface of the housing is provided with a first indicator light which is lit when the motor is started and a second indicator light which is lit when the motor is stopped.

Preferably, the electric vehicle further comprises a forward and reverse rotation control button which is arranged on the shell and connected with the motor; a third indicator light is arranged on the surface of the shell; the first indicator signal of the third indicator light corresponds to forward rotation of the motor, and the second indicator signal of the third indicator light corresponds to reverse rotation of the motor.

Compared with the prior art, the electric screwdriver provided by the utility model comprises a striking shaft, a motor, a planetary speed reducing mechanism, a transmission shaft and a torque monitoring mechanism; the transmission shaft is arranged between the motor and the planetary reduction mechanism, and the torque monitoring mechanism is arranged between the planetary reduction mechanism and the striking shaft.

In the electric screwdriver, one end of a transmission shaft is clamped and tightly matched with an output shaft of a motor, and the other end of the transmission shaft is provided with a gear part which is internally engaged and fixed with a sun gear of a planetary speed reducing mechanism.

In the electric screwdriver, a torque monitoring mechanism comprises a driving shaft, a clutch sleeve, a steel ball and a displacement detector; the driving shaft is connected to the output end of the planetary speed reducing mechanism, and the clutch end II of the driving shaft is connected to the clutch end I of the striking shaft through the clutch sleeve and the steel ball.

Wherein, the clutch sleeve is internally provided with a circular truncated cone-shaped inner wall, and the clutch sleeve, the clutch end I and the clutch end II are sequentially sleeved from outside to inside. A plurality of steel ball channels which are distributed in a circular array and are radially communicated are arranged in the circumferential direction of the clutch end I; a plurality of bulges distributed in a circular array are arranged in the circumferential direction of the clutch end II, and any bulge extends outwards to a bulge along the radial direction of the clutch end II; the steel ball is arranged in the steel ball channel of the clutch end I. The circumference of clutch end II is equipped with a plurality of bellying, has formed clutch end II's depressed part between two adjacent bellying. When the clutch end I is sleeved on the periphery of the clutch end II, the convex part contacts the inner wall of the clutch end I, and the concave part is separated from the inner wall of the clutch end I. When the concave part of the clutch end II is aligned with the steel ball channel of the clutch end I, the steel ball can be closer to the central shaft of the clutch end II along the through direction of the steel ball channel; and when the bulge part of the clutch end II is aligned with the steel ball channel of the clutch end I, the bulge part can eject the steel ball outwards along the through direction of the steel ball channel.

According to the magnitude relation between the resistance torque transmitted to the driving shaft by an external workpiece through the striking shaft and the driving torque transmitted to the driving shaft by the motor through the transmission shaft and the reducer assembly, the clutch end II can be kept relatively static with the clutch end I by the angle of the protruding part abutting against the clutch end I, the clutch end II can also rotate in the clutch end I until the protruding part is aligned with the steel ball channel, so that a steel ball is ejected outwards, the steel ball applies pressure to the clutch sleeve sleeved on the periphery of the clutch end I and the circular truncated cone-shaped inner wall of the clutch sleeve, the clutch sleeve generates displacement along the axial direction of the clutch sleeve, the torque conversion between the striking shaft and the driving shaft is converted into the displacement of the clutch sleeve, the torque monitoring mechanism detects the displacement by using the displacement detector and automatically turns off the motor when the displacement reaches a set value II, and the torque setting operation of the electric screwdriver is realized.

In summary, in the electric screwdriver provided by the utility model, on one hand, the transmission shaft is utilized to realize the integrated assembly of the motor and the planetary reduction mechanism, the assembly precision is improved, and the transmission characteristics of low rotating speed and high torque can be met; on the other hand, on the basis that the driving shaft truly and accurately reflects the actual torque of the motor, the torque monitoring mechanism is utilized to monitor the displacement of the clutch sleeve in real time and accurately, and whether the electric screwdriver realizes the fixed torque or not is judged according to whether the displacement reaches the set value II or not, so that the operating state of the electric screwdriver is automatically and accurately controlled.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

Fig. 1 is a schematic structural diagram of an electric screwdriver according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a torque monitoring mechanism provided in an embodiment of the present invention in a first state;

FIG. 3 is a cross-sectional view taken along line D-D of FIG. 2;

fig. 4 is a schematic structural diagram of a torque monitoring mechanism provided in an embodiment of the present invention in a second state;

FIG. 5 is a cross-sectional view taken along line E-E of FIG. 4;

FIG. 6 is a schematic view of a driving shaft according to an embodiment of the present invention in a first direction;

FIG. 7 is a schematic view of a drive shaft according to an embodiment of the present invention in a second orientation;

fig. 8 is an exploded view of the planetary reduction mechanism, the transmission shaft and the motor according to the embodiment of the present invention;

FIG. 9 is a schematic view of the assembly of the planetary reduction mechanism, the transmission shaft and the motor according to the embodiment of the present invention;

fig. 10 is a partial schematic view of an electric screwdriver provided in an embodiment of the present invention at a gear portion;

fig. 11 is a partial schematic view of a powered screwdriver at the end of a socket according to an embodiment of the present invention.

The device comprises a machine shell 1, a striking shaft 2, a clutch end I20, a steel ball channel 21, a motor 3, an output shaft 31, a planetary speed reducing mechanism 4, a sun gear 41, a planet gear 42, a speed reducer machine shell 43, a speed reducer bracket 44, a transmission shaft 5, a gear part 51, a sleeve end 52, a driving shaft 61, a clutch end II610, a boss 6101, a recess 6102, a clutch 62, a steel ball 63, a spring I8, a retainer ring 10, a mandril 11, a spring II12, a proximity switch 13, a lighting lamp 14, a control button 15 for positive and negative rotation, a switch 16 and a controller 17.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In order that those skilled in the art will better understand the disclosure, the utility model will be described in further detail with reference to the accompanying drawings and specific embodiments.

Referring to fig. 1 to 11, fig. 1 is a schematic structural view of an electric screwdriver according to an embodiment of the present invention; FIG. 2 is a schematic structural diagram of a torque monitoring mechanism provided in an embodiment of the present invention in a first state; FIG. 3 is a cross-sectional view taken along line D-D of FIG. 2; fig. 4 is a schematic structural diagram of a torque monitoring mechanism provided in an embodiment of the present invention in a second state; FIG. 5 is a cross-sectional view taken along line E-E of FIG. 4; FIG. 6 is a schematic view of a driving shaft according to an embodiment of the present invention in a first direction; FIG. 7 is a schematic view of a drive shaft according to an embodiment of the present invention in a second orientation; fig. 8 is an exploded view of the planetary reduction mechanism, the transmission shaft and the motor according to the embodiment of the present invention; FIG. 9 is a schematic view of the assembly of the planetary reduction mechanism, the transmission shaft and the motor according to the embodiment of the present invention; fig. 10 is a partial schematic view of an electric screwdriver provided in an embodiment of the present invention at a gear portion; fig. 11 is a partial schematic view of a powered screwdriver at the end of a socket according to an embodiment of the present invention. Fig. 9 to 11 are cross-sectional views, and the specific cross-sectional direction can be understood with reference to other drawings.

The utility model provides an electric screwdriver which comprises a striking shaft 2, a motor 3, a planetary speed reducing mechanism 4, a transmission shaft 5 and a torque monitoring mechanism. In the electric screwdriver, a transmission shaft 5 is provided between a motor 3 and a planetary reduction mechanism 4, and a torque monitoring mechanism is provided between the planetary reduction mechanism 4 and a striking shaft 2.

In the electric screwdriver, one end part of the transmission shaft 5 is clamped and sleeved on the output shaft 31 of the motor 3 and is tightly matched and installed with the output shaft 31 of the motor 3, for example, the transmission shaft 5 is clamped and sleeved on the outer peripheral surface of the output shaft 31 through the inner cylinder wall of the sleeve end 52; the other end of the transmission shaft 5 has a gear portion 51 that engages with the sun gear 41 of the planetary reduction mechanism 4, that is, the central portion of the sun gear 41 of the planetary reduction mechanism 4 is provided with an inner tooth face, and the gear portion 51 of the transmission shaft 5 has an outer tooth face, so that the transmission shaft 5 is fixedly connected to the planetary reduction mechanism 4 in such a manner that the outer tooth face engages with the inner tooth face of the sun gear 41.

The external tooth flanks and the internal tooth flanks mesh with each other to fix the propeller shaft 5 and the planetary reduction gear 4 relative to each other, which means that the gear wheel 51 cannot rotate in the sun wheel 41, and the teeth in the circumferential direction of the gear wheel 51 are clamped in the tooth grooves of the sun wheel 41.

In the electric screwdriver, a torque monitoring mechanism comprises a driving shaft 61, a clutch sleeve 62, a steel ball 63 and a displacement detector; the drive shaft 61 is connected to the output end of the planetary reduction mechanism 4, and the drive shaft 61 is connected to the striking shaft 2 through a clutch sleeve 62 and a steel ball 63. The driving shaft 61 is provided with a clutch end II610, the striking shaft 2 is provided with a clutch end I20, a circular truncated cone-shaped inner wall is arranged in the clutch sleeve 62, the clutch end II610 penetrates through a hole of the clutch end I20, the circular truncated cone-shaped inner wall is sleeved on the periphery of the clutch end I20, and in short, the clutch sleeve 62, the clutch end I20 and the clutch end II610 are sequentially sleeved from outside to inside.

In the torque monitoring mechanism, a plurality of steel ball channels 21 distributed in a circular array are arranged in the circumferential direction of a clutch end I20, and any one steel ball channel 21 is arranged in a penetrating manner along the radial direction of the clutch end I20; a plurality of protrusions 6101 distributed in a circular row are arranged in the circumferential direction of the clutch end II610, and any one of the protrusions 6101 extends outward to a protrusion along the radial direction of the clutch end II 610; the steel ball 63 fits into the ball channel 21 of the clutch end I20. Generally, the number of the steel balls 63, the steel ball channels 21 and the bosses 6101 are equal, all the steel balls 63 are assembled in all the steel ball channels 21 in a one-to-one correspondence, and all the bosses 6101 are rotatable to be aligned with all the steel ball channels 21 one by one.

Since the plurality of protrusions 6101 are disposed in the circumferential direction of the clutch end II610, a recess 6102 of the clutch end II610 is formed between two adjacent protrusions 6101. When the clutch end I20 is sleeved on the outer periphery of the clutch end II610, the protrusion 6101 contacts the inner wall of the clutch end I20, and the recess 6102 is separated from the inner wall of the clutch end I20. When the recess 6102 of the clutch end II610 is aligned with the ball channel 21 of the clutch end I20, the ball 63 may be closer to the center axis of the clutch end II610 in the through direction of the ball channel 21; when the protrusion 6101 of the clutch end II610 is aligned with the ball channel 21 of the clutch end I20, the protrusion 6101 pushes the ball 63 outward along the through direction of the ball channel 21. Wherein, the recess 6102 may have a sliding curved surface extending smoothly and gently to the protrusion 6101 along the radial direction of the clutch end II610, as shown in fig. 6 and 7, which is beneficial to ensure that the clutch end II610 rotates smoothly in the clutch end I20 and pushes the steel ball 63 to move smoothly along the steel ball channel 21.

When the electric screwdriver is used, the clutch end I20 and the clutch end II610 have two motion states of relative rest and relative rotation according to the stress condition of the striking shaft 2 and the driving shaft 61 under different working states. The above-mentioned relative rest means that when the actual resistance torque transmitted from the external workpiece to the driving shaft 61 via the striking shaft 2 does not reach the preset resistance torque, the protrusion 6101 of the clutch end II610 abuts against the inner wall of the clutch end I20, and at this time, the friction between the protrusion 6101 and the inner wall is sufficient to maintain the relative rest of the clutch end I20 and the clutch end II610, so that the driving shaft 61 drives the striking shaft 2 to rotate synchronously. The relative rotation means that when the actual resistance torque transmitted from the external workpiece to the driving shaft 61 via the striking shaft 2 reaches the preset resistance torque, the friction force between the protrusions 6101 and the inner wall is not enough to maintain the relative standstill of the clutch end I20 and the clutch end II610, so that the clutch end II610 starts to rotate in the clutch end I20.

Once clutch end II610 is rotated within clutch end I20 until boss 6101 is aligned with ball channel 21, for a single boss 6101, boss 6101 will eject ball 63 outward in the direction of penetration of ball channel 21; for all the protrusions 6101, all the protrusions 6101 push all the steel balls 63 to spread outward around the clutch end II610 at the same time. Because the two ends of the steel ball channel 21 in the penetrating direction respectively face the clutch end II610 and the circular truncated cone-shaped inner wall of the clutch sleeve 62, all the steel balls 63 which diffuse outward with the clutch end II610 as the center exert an acting force on the circular truncated cone-shaped inner wall, and on the premise that the steel balls 63 are constrained by the steel ball channel 21 and cannot generate axial displacement along the clutch sleeve 62, the acting force can cause the clutch sleeve 62 and the circular truncated cone-shaped inner wall to generate axial displacement along the clutch sleeve 62.

It can be seen that the torque monitoring mechanism can convert the torque change between the driving shaft 61 and the striking shaft 2 into a displacement change, so as to detect the displacement of the clutch sleeve 62 by using the displacement detector, thereby determining whether the working torque of the electric screwdriver reaches the set value of the user. The displacement detector of the torque monitoring mechanism is connected with the motor 3, when the displacement detector detects that the displacement of the clutch sleeve 62 reaches a set value II, which means that the working torque of the electric screwdriver reaches a set value I, the motor 3 can be automatically shut down, the output shaft 31 of the motor 3 does not work on the striking shaft 2 through the driving shaft 61 any more, so that a user can be ensured to accurately control the actual working torque of the electric screwdriver at the set value I of the user.

In summary, the electric screwdriver utilizes the torque monitoring mechanism to convert the torque change between the driving shaft 61 and the striking shaft 2 into the displacement change of the clutch sleeve 62 and monitor the displacement, and simultaneously, the motor 3 is automatically controlled according to the monitoring result, so as to realize the accurate control of the torque of the electric screwdriver. In the torque monitoring mechanism, the motion parameters of the driving shaft 61 and the clutch end II610 thereof actually represent the motion parameters of the motor 3, and since the motor 3 is connected to the driving shaft 61 through the planetary reduction mechanism 4, the electric screwdriver utilizes the transmission shaft 5 to connect the motor 3 and the planetary reduction mechanism 4, on one hand, the low-speed high-torque output of the electric screwdriver is realized, and the torque monitoring mechanism is convenient to monitor the displacement of the clutch sleeve 62; on the other hand, the integrated assembly effect of the motor 3 and the planetary reduction mechanism 4 is improved, the motion transmission precision of the planetary reduction mechanism 4 between the motor 3 and the driving shaft 61 is improved, the driving shaft 61 can truly and reliably reflect the actual motion state of the output shaft 31 of the motor 3, and a solid and reliable guarantee is provided for the torque monitoring mechanism to play a role.

The electric screwdriver provided by the utility model is further described with reference to the accompanying drawings and the embodiment.

The planetary reduction mechanism 4 adopted for the present invention may include a sun gear 41, a planet gear 42 and a reducer housing 4343; the sun wheel 41 and the planet wheel 42 are positioned and arranged in a reducer shell 4343; the surface of the reducer housing 4343 is provided with a mounting opening through which the gear portion 51 can be inserted.

The sun wheel 41 and the planet wheels 42 are positioned and mounted in a reducer housing 4343, for example, the reducer housing 4343 is provided with a reducer support 44 fixed opposite to the reducer housing 4343, a plurality of planet wheels 42 are distributed around the sun wheel 41 and are engaged with the external tooth surface of the sun wheel 41, and any one of the planet wheels 42 is also engaged with the internal tooth ring of the detector support.

The surface of the reducer housing 4343 is provided with a mounting opening through which the gear portion 51 can be inserted. The mounting opening is aligned with the inner flank of the sun gear 41 and is sized slightly larger than the gear portion 51. The reducer housing 4343 with the mounting port can integrate all parts of the planetary reduction mechanism 4 into a modular assembly, so that the whole planetary reduction mechanism 4 can be replaced in an electric screwdriver in an assembly mode. Meanwhile, the reducer housing 4343 with the mounting opening also provides a structural basis for mounting operation for the sun gear 41 of the transmission shaft 5 inserted into the planetary reduction mechanism 4 quickly, which is beneficial to simplifying the assembly difficulty of the transmission shaft 5 and the planetary reduction mechanism 4 with a plurality of parts.

In the torque monitoring mechanism of the present invention, the striking shaft 2, the drive shaft 61, and the output shaft 31 of the motor 3 are connected in this order.

Taking the orientation shown in fig. 1 as an example, the striking shaft 2, the driving shaft 61 and the output shaft 31 of the motor 3 are sequentially distributed and connected from left to right, and a user engages and disengages the left end of the striking shaft 2 to connect with an external workpiece, so as to apply work to the workpiece, and tighten or loosen the workpiece.

In the above configuration, the clutch sleeve 62 may be attached at an angle such that the small diameter end of the circular truncated cone-shaped inner wall faces the striking shaft 2. The axial two ends of the circular truncated cone-shaped inner wall are respectively a large-diameter end and a small-diameter end, and the diameter of the small-diameter end is smaller than that of the large-diameter end. When all the steel balls 63 are pushed by all the protrusions 6101 and spread outward to the peripheral side of the drive shaft 61, all the steel balls 63 push the clutch sleeve 62 and the circular truncated cone-shaped inner wall thereof to move toward the small-diameter end of the clutch sleeve 62, that is, to move from right to left in the horizontal direction of fig. 1. This direction of movement of the clutch sleeve 62 is adapted to the shape and size of the striking shaft 2 at the clutch end I20, which is advantageous for the installation and placement of the displacement detector in the housing 1.

Further, the torque monitoring mechanism further comprises a reference block and a spring I8; the reference block is arranged on the striking shaft 2, and the spring I8 is sleeved on the striking shaft 2. The reference block, the clutch sleeve 62 and the motor 3 are distributed in sequence along the axial direction of the striking shaft 2. The spring I8 is arranged between the reference block and the clutch sleeve 62, and the axial two ends of the spring I8 are respectively abutted against the reference block and the clutch sleeve 62.

Therefore, when the clutch sleeve 62 is pressed by the steel ball 63 to be linearly displaced in the axial direction thereof, the clutch sleeve 62 compresses the spring I8 toward the reference block. Once the motor 3 is automatically turned off, the spring I8 expands in return to push the clutch sleeve 62 to move toward the motor 3, and the clutch sleeve 62 applies a force to the clutch end II610 through the steel ball 63, so that the clutch end II610 rotates from the state shown in fig. 4 and 5 back to the state shown in fig. 2 and 3.

As described above, the torque monitoring means determines whether the operating torque of the electric screwdriver reaches a set value corresponding to a predetermined value that the user should input in advance to the electric screwdriver according to his/her own needs, based on the displacement amount of the clutch sleeve 62, and automatically turns off the motor 3 when the operating torque of the electric screwdriver reaches the set value. Based on the connection relationship of the spring I8 in the torque monitoring mechanism, the spring I8 not only can realize the automatic reset of the torque monitoring mechanism, but also can be used for adjusting the set value of the electric screwdriver to realize the fixed-torque adjustment.

The specific means that the pre-pressure in the spring I8 is adjusted by adjusting the distance between the reference block and the clutch sleeve 62 by adopting the spring I8, so that the acting force required when the steel ball 63 pushes the clutch sleeve 62 to move for a specific displacement is changed. The larger the acting force is, the larger the set value of the electric screwdriver is, the larger the torque needs to be transmitted to the driving shaft 61 by the striking shaft 2 from the external workpiece, so that the motor 3 can be automatically turned off after working for a period of time; the smaller the force, the smaller the setting of the electric screwdriver, and the smaller the torque transmitted from the external workpiece to the driving shaft 61 via the striking shaft 2, the motor 3 can be automatically turned off after a certain time.

As to the manner in which the fixed-torque adjuster effects the reference block approaching and moving away from the clutch sleeve 62, this includes, but is not limited to, the use of a transmission assembly having an adjusting toothed disc as the primary structure. In addition, in order to adjust the pre-pressure of the spring I8 through the fixed-torque adjuster, the machine shell 1 is provided with a torque adjusting channel and a dust cover; the casing 1 is located to the one end of transferring the passageway, with external intercommunication, transfers the other end of turning the button the passageway and extends to and surely turns round the regulator, and convenience of customers operates, adjusts the passageway and blocks through the dust cover, avoids external impurity to get into casing 1.

Further, the outer periphery of the clutch end I20 can be sleeved with a retaining ring 10, and the retaining ring 10 slides along the axial direction of the striking shaft 2; one side of the striking shaft 2 is provided with a mandril 11 parallel to the striking shaft 2; the displacement detector is disposed next to the jack 11. The clutch sleeve 62 pushes the ejector rod 11 to move through the retainer ring 10, and the displacement detector indirectly judges the displacement of the clutch sleeve 62 through the moving distance of the ejector rod 11.

The displacement detector may comprise a proximity switch 13, which proximity switch 13 is aligned with the rod axial end of the push rod 11. When the push rod 11 moves under the action of the clutch sleeve 62 and the retainer ring 10, the rod body shaft end of the push rod 11 moves relative to the proximity switch 13, so that the proximity switch 13 acquires a moving signal of the push rod 11.

Compare in the displacement that adopts displacement detector direct detection separation and reunion cover 62, add retaining ring 10 and ejector pin 11 between separation and reunion cover 62 and displacement detector, be favorable to the overall arrangement of the different spare parts of reasonable adjustment in casing 1, under the prerequisite of the displacement of realizing detecting separation and reunion cover 62, simplify the shape structure of separation and reunion cover 62, conveniently adopt among the prior art common all kinds of displacement detector to come the displacement of short-term test separation and reunion cover 62.

In order to improve the operation convenience of the electric screwdriver, the torque transmission mechanism further comprises a spring II12 sleeved on the ejector rod 11, and the spring II12 is used for realizing the reset of the ejector rod 11. One axial end of the spring II12 is fixed relative to the casing 1, and the other axial end of the spring II12 abuts against a stopper in the middle of the ejector rod 11; the proximity switch 13 is arranged at one end of the ejector rod 11 far away from the spring II 12.

In order to facilitate the operation of a user, the electric screwdriver further comprises a first indicator light and a second indicator light which are arranged on the surface of the machine shell 1; the first indicator lamp is turned on when the motor 3 is started, and the second indicator lamp is turned on when the motor 3 is turned off. Through first pilot lamp and second pilot lamp, the user can judge directly perceivedly fast that motor 3 stops the state, this electric screwdriver of better use.

The first indicator light and the second indicator light can be distinguished only by different installation positions of the first indicator light and the second indicator light on the machine shell 1, and can also be distinguished by combining the light colors of the first indicator light and the second indicator light. For example, the first indicator light is a red light which is continuously turned on when the electric screwdriver is turned on and the torque does not reach the set value I; the second indicator light is a green light which is turned on when the torque of the electric screwdriver reaches the set value I, and at the same time, the motor 3 is also automatically turned off according to the detection result of the displacement detector. The actions of the motor 3 and various indicator lights described above can be collectively controlled by the controller 17.

The electric screwdriver also comprises a forward and reverse rotation control button 15 which is arranged on the shell 1 and connected with the motor 3; meanwhile, a third indicator light is arranged on the surface of the machine shell 1; the first indicator signal of the third indicator lamp corresponds to the forward rotation of the motor 3, and the second indicator signal of the third indicator lamp corresponds to the reverse rotation of the motor 3. The first indicator signal and the second indicator signal of the third indicator light may be distinguished by a flashing state of the third indicator light, or may be distinguished by a color of the third indicator light, for example, if the third indicator light indicates that the electric screwdriver is in a reverse rotation state by a blue light, the third indicator light may indicate that the electric screwdriver is in a forward rotation state by turning off the third indicator light or extending other than blue.

In addition, the electric screwdriver may further include a fourth indicator light for displaying the amount of power of the battery pack in the casing 1. For example, when the fourth indicator light emits yellow light, it means that the battery pack of the electric screwdriver is about to be dead, and an operator is required to charge or replace the battery pack in time.

Besides the above-mentioned various indicator lights, the electric screwdriver can be provided with an illuminating lamp 14 at the front end of the casing 1, so as to meet the requirement that the electric screwdriver is used in an environment with insufficient light. The switch 16 of the electric screwdriver can be arranged at the inner corner of the handle of the machine shell 1, so that an operator can conveniently press the switch 16 when holding the handle of the machine shell 1.

The electric screwdriver provided by the utility model is described in detail above. The principles and embodiments of the present invention are explained herein using specific examples, which are presented only to assist in understanding the method and its core concepts. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

Claims (10)

1. An electric screwdriver comprises a shell (1), a striking shaft (2) and a motor (3) which are arranged in the shell (1), and is characterized by further comprising a planetary speed reducing mechanism (4), a transmission shaft (5) and a torque monitoring mechanism; one end of the transmission shaft (5) is clamped and tightly matched with an output shaft (31) of the motor (3), and the other end of the transmission shaft (5) is provided with a gear part (51) which is internally meshed with and fixed with a sun gear (41) of the planetary reduction mechanism (4);

the torque monitoring mechanism comprises a driving shaft (61), a clutch sleeve (62), a steel ball (63) and a displacement detector;

the circular truncated cone-shaped inner wall of the clutch sleeve (62), the clutch end I (20) of the striking shaft (2) and the clutch end II (610) of the driving shaft (61) are sequentially sleeved from outside to inside; a plurality of steel ball channels (21) which are annularly distributed and are penetrated along the radial direction are arranged on the circumferential direction of the clutch end I (20); a plurality of annularly distributed and radially extending protrusions (6101) are arranged on the circumferential direction of the clutch end II (610); the number of the steel balls (63), the number of the steel ball channels (21) and the number of the convex parts (6101) are equal; any one boss (6101) is in contact fit with the inner wall of the clutch end I (20) when the working torque does not reach a set value I, and rotates and pushes the steel ball (63) to move outwards along the steel ball channel (21) to squeeze the circular truncated cone-shaped inner wall when the working torque reaches the set value I; the displacement detector automatically shuts down the motor (3) when the displacement of the clutch sleeve (62) reaches a set value II.

2. Electric screwdriver according to claim 1, characterised in that said planetary reduction mechanism (4) comprises said sun (41), planet (42) and a reducer casing (43); the sun wheel (41) and the planet wheel (42) are positioned and installed in the speed reducer shell (43); the surface of the speed reducer casing (43) is provided with a mounting opening through which the gear part (51) can penetrate.

3. The electric screwdriver according to claim 1, characterized in that said striking shaft (2), said driving shaft (61) and said output shaft (31) of said motor (3) are connected in sequence; the small-diameter end of the circular truncated cone-shaped inner wall faces the striking shaft (2).

4. The electric screwdriver according to claim 3, characterized by further comprising a reference block arranged on said striking shaft (2) and a spring I (8) sleeved on said striking shaft (2); the reference block, the clutch sleeve (62) and the motor (3) are sequentially distributed along the axial direction of the striking shaft (2), and two axial ends of the spring I (8) are respectively abutted to the clutch sleeve (62) and the reference block.

5. The electric screwdriver according to claim 4, wherein said torque monitoring mechanism further comprises a torque setting adjuster connected to said reference block for moving said reference block in the axial direction of said striking shaft (2).

6. The electric screwdriver according to claim 5, wherein said casing (1) is provided with a torque adjusting channel connected to said torque setting adjuster and a dust cover shielding said torque adjusting channel.

7. The electric screwdriver according to claim 4, characterized in that the outer circumference of the clutch end I (20) is sleeved with a retaining ring (10), and the retaining ring (10) slides along the axial direction of the striking shaft (2); ejector rods (11) which are distributed in parallel are arranged on one side of the striking shaft (2); the clutch sleeve (62) pushes the ejector rod (11) to move along the axial direction of the ejector rod (11) through the retainer ring (10); the displacement detector is arranged next to the ram (11).

8. The electric screwdriver according to claim 7, characterized in that the ejector pin (11) is sleeved with a spring II (12); one axial end of the spring II (12) is fixed relative to the shell (1), and the other axial end of the spring II abuts against a blocking body (111) in the middle of the ejector rod (11); the displacement detector is embodied as a proximity switch (13); the proximity switch (13) is arranged at one end of the ejector rod (11) far away from the spring II (12).

9. The electric screwdriver according to any one of claims 1 to 8, characterized in that the surface of said casing (1) is provided with a first indicator light that is lit when said motor (3) is activated and a second indicator light that is lit when said motor (3) is deactivated.

10. The electric screwdriver according to any one of claims 1 to 8, further comprising a forward and reverse rotation control button disposed on the casing (1) and connected to the motor (3); a third indicator light is arranged on the surface of the machine shell (1); the first indicator signal of the third indicator light corresponds to forward rotation of the motor (3), and the second indicator signal of the third indicator light corresponds to reverse rotation of the motor (3).

Images