CN202702198U

CN202702198U - Power tool

Info

Publication number: CN202702198U
Application number: CN201220290564XU
Authority: CN
Inventors: 庞晓丽; 钟红风
Original assignee: Positec Power Tools Suzhou Co Ltd
Current assignee: Positec Power Tools Suzhou Co Ltd
Priority date: 2011-08-06
Filing date: 2012-06-20
Publication date: 2013-01-30
Anticipated expiration: 2022-06-20
Also published as: CN102909678B; CN102909703B; CN104385206B; CN102909702B; CN104385205B; CN202702199U; CN104476472B; CN104385205A; CN102909679B; CN202702200U; CN102909676B; CN102909709A; CN102909676A; CN102909702A; CN102909677B; CN104801744B; CN102909679A; CN104385206A; CN202702201U; CN102909703A

Abstract

The utility model relates to a power tool which comprises a main case, a motor, an output shaft, a transmission mechanism, a work head support mechanism and a connecting shaft, wherein the motor is arranged in the main case and outputs rotary power; the output shaft is provided with a containing hole arranged in the axial direction and used for containing a work head; the transmission mechanism is arranged between the motor and the output shaft and can transmit the rotary power output by the motor to the output shaft; the work head support mechanism is arranged in the main case and is provided with a plurality of containing spaces arranged in parallel which are used for supporting the work head, and the work head support mechanism can be adjusted to a position where one of the containing spaces is axially corresponding to the output shaft; the connecting shaft is arranged in the main case and can move between two positions to drive the working position of the work head in the containing hole or the containing position of the work head in the work head support mechanism; and the transmission mechanism comprises a self-locking device, and the self-locking device is used for transmitting the rotary power of the motor to the output shaft in a single direction.

Description

Power tool

Technical Field

The utility model relates to a power tool especially relates to a can realize storage of working head and gun drill class power tool of quick replacement.

Background

Among the existing power tools of the gun drill type, electric drills, electric screwdrivers and impact drills are generally included.

A power screwdriver is a commonly used power tool for tightening screws onto a workpiece. When screws with different specifications need to be screwed down in the using process, different working heads, namely bits, need to be replaced according to the specifications of the screws, namely the originally installed working head needs to be taken down and then a working head with another structure is installed. In the use occasion that the working head needs to be replaced frequently, great inconvenience is brought to an operator, on one hand, the working head is troublesome to replace, and on the other hand, the taken-off working head is easy to lose everywhere. Although some of the hand tools can achieve storage and quick replacement of the working head, the hand tools are not suitable for use as professional tools in the industrial industry due to their inherent disadvantages, i.e., low torque and laborious operation, which makes the operator easily fatigued and inefficient.

Chinese utility model patent CN201086280Y discloses a multitool head electric tool, including electric tool main part and multitool head runner structure, multitool head runner structure includes a multitool head runner section of thick bamboo that can accept a plurality of tool bits, but multitool head runner section of thick bamboo endwise slip links to each other with the tool main part, when multitool head runner section of thick bamboo slides to the position of keeping away from the tool main part, thereby the rotatory multitool head runner section of thick bamboo of accessible selects the tool bit that needs. However, when the multi-cutter-head rotating-wheel cylinder is far away from the tool main body, the connecting shaft of the multi-cutter-head rotating-wheel cylinder is exposed outside, dust and powder can enter the inside of the electric tool or the inside of the multi-cutter-head rotating-wheel cylinder in the sliding process of the multi-cutter-head rotating-wheel cylinder, and the multi-cutter-head rotating-wheel cylinder cannot rotate to select the cutter head or directly cause the electric tool to be unusable after a long time. And the working head is propped against the workpiece when the multi-tool-bit electric tool works, so that the connecting shaft needs to bear the acting force in the opposite direction, the connecting shaft can bring pressure to the transmission mechanism, and the transmission mechanism can not transmit the torque to the connecting shaft, and the structure also ensures that the transmission of the multi-tool-bit electric tool is unreliable.

Moreover, if an operator closes the motor and manually rotates the cutter head, the cutter head can be triggered to drive the connecting shaft to rotate, so that the motor can be damaged by the rotation of the motor, the screw cannot be screwed up by manual operation, and great inconvenience is brought to the operator.

In addition, when changing the tool bit, need earlier return to the runner section of thick bamboo to the tool bit, in order to prevent that the tool bit from being held by magnet and leaving from the runner section of thick bamboo when the runner section of thick bamboo axial displacement, chinese utility model patent CN201086280Y discloses it prevents that the tool bit from breaking away from the runner section of thick bamboo through the mode of setting up solid fixed ring on the tool bit, but such tool bit needs to be customized specially for the use of instrument does not have the commonality. And the rotation of the tool bit driven directly by the spindle is relatively unstable because the longer the length of the spindle, the greater the run-out of the spindle, which brings some potential risks to the user of the tool. Furthermore, because the rotating wheel cylinder needs to move axially and be separated from the main shaft, dust and other impurities can easily enter the rotating wheel cylinder, and the rotating wheel cylinder cannot be cleaned.

SUMMERY OF THE UTILITY MODEL

To the not enough of prior art, the utility model aims to provide a convenient operation's power tool.

The utility model provides a technical scheme that its technical problem adopted is: a power tool, comprising: a housing; a motor disposed in the housing and outputting rotational power; the output shaft is provided with an accommodating hole which is axially arranged and used for accommodating the working head; the transmission mechanism is arranged between the motor and the output shaft and can transmit the rotary power output by the motor to the output shaft; the working head supporting mechanism is arranged in the shell and provided with a plurality of accommodating spaces which are used for supporting the working heads and are arranged in parallel, and the working head supporting mechanism can be adjusted to a position where one accommodating space axially corresponds to the output shaft; the connecting shaft is arranged in the machine shell and can move between two positions to drive the working head to be positioned at a working position in the accommodating hole or at an accommodating position of the working head supporting mechanism; the transmission mechanism comprises a self-locking device, and the self-locking device is used for transmitting the rotating power of the motor to the output shaft in a one-way mode.

Preferably, the transmission mechanism includes a planetary gear reduction mechanism driven by a motor and a gear mechanism driven by the planetary gear reduction mechanism, and the self-locking device is disposed between the planetary gear reduction mechanism and the gear mechanism.

Preferably, the self-locking device comprises an adapter disc connected with the gear reduction mechanism and used for driving the gear mechanism, a fixed disc fixedly connected with the shell, and an intermediate transmission mechanism used for connecting the adapter disc and the fixed disc to realize one-way transmission.

Preferably, the planetary gear reduction mechanism comprises an output end planet carrier, an external spline is arranged on the switching disc, and the external spline is connected with an internal spline arranged on the output end planet carrier.

Preferably, the external spline and the internal spline are in loose fit along the circumferential direction.

Preferably, the intermediate transfer mechanism comprises at least one plane circumferentially arranged on the outer surface of the adapter plate, an inner circular surface of the fixed plate and at least one roller positioned between the plane and the inner circular surface of the fixed plate.

Preferably, the output end planet carrier comprises a plurality of legs extending between the plane and the inner circular surface, and the roller is located between two adjacent legs.

Preferably, the outer surface of the fixed disk is provided with a projection for fixedly connecting with the shell.

Preferably, the gear mechanism includes a first gear connected to the planetary gear reduction mechanism, a third gear for driving the output shaft, and a second gear meshed with both the first gear and the third gear.

Preferably, the connecting shaft is connected between a transmission mechanism and the output shaft, and the transmission mechanism transmits the rotary power output by the motor to the output shaft through the connecting shaft.

Compared with the prior art, the beneficial effects of the utility model are that: the utility model discloses a power tool makes power tool be suitable for the multiple mode operation through setting up self-lock device, makes things convenient for the operator to use in multiple occasion.

Drawings

Fig. 1 is a cross-sectional view of a preferred power tool of the present invention in an operational state.

Fig. 2 is a partially exploded perspective view of the power tool of fig. 1.

Fig. 3 is a schematic cross-sectional view of the power tool of fig. 1 taken along line E-E.

Figure 4 is a cross-sectional schematic view of another embodiment of the pinion mechanism of the power tool of figure 3.

Fig. 5 is a cross-sectional view of the power tool of fig. 1 in a state of changing the working head.

Fig. 6 is an exploded perspective view of the self-locking device portion of the power tool of fig. 5.

Fig. 7 is a sectional view taken along the direction F-F in fig. 5.

Fig. 8 is a reference view of the self-locking device in fig. 7 in a use state (when the output end planet carrier rotates counterclockwise).

Fig. 9 is a reference view of the self-locking device in fig. 7 in a use state (when the adapter plate rotates clockwise).

FIG. 10 is a schematic view of the first embodiment of the power tool of FIG. 1 limiting the rearward movement of the work head with respect to the connecting shaft when the work head is replaced.

Fig. 11 is a schematic view of the blocking member of fig. 10 in a position allowing movement of the connecting shaft.

FIG. 12 is a schematic view of the blocking member of FIG. 10 in a position to limit the backward movement of the working head.

FIG. 13 is a schematic view of the second embodiment of the power tool of FIG. 1 limiting the rearward movement of the work head with respect to the connecting shaft when the work head is replaced.

Fig. 14 is a schematic view of the blocking member of fig. 13 in a position allowing movement of the connecting shaft.

FIG. 15 is a schematic view of the blocking member of FIG. 13 in a position to limit the backward movement of the working head.

FIG. 16 is a schematic view of a third embodiment of the power tool of FIG. 1 limiting the rearward movement of the work head with the connecting shaft when the work head is replaced.

FIG. 17 is a schematic view of a fourth embodiment of the power tool of FIG. 1 limiting the rearward movement of the work head with respect to the connecting shaft when the work head is replaced.

Fig. 18 is a schematic view of the working head of fig. 16 restrained from backing up with the connecting shaft, wherein the connecting shaft drives the working head back to the storage clip and the connecting shaft is moved away from the storage clip.

FIG. 19 is a view similar to FIG. 18 with the storage clip rotated and the working head abutting the guide surface.

Fig. 20 is a view similar to fig. 18, with the storage clip rotated and the working head axially separated from the connecting shaft by the guide surface.

Wherein,

1. case 2, motor 3, transmission mechanism

4. Output shaft 6, battery 7, button switch

9. Working head 11, handle 13 and front shell

15. Guide groove 21, motor shaft 22, gear box

30. Pinion gear mechanism 31, planetary gear reduction mechanism 40, sleeve

41. Receiving hole 50, fixing block 51, connecting shaft

52. Storage clip 53, sliding cover 54, steel cap

56. U-shaped spring 57, spring plate 81 and limit block

131. Opening 133, opening 134, radial through hole

221. Partition 223, gearbox cover 225, arch

301. First gear 302, second gear 303, third gear

308. Gear shaft 313, output end planet carrier 321 and fixed disc

322. The transfer disc 323, the roller 511 and the magnet

512. Supporting end 521, accommodating bin 522, pressing plate

523. Opening 526. U-shaped groove 531. guide rail

535. First lug 536, second lug 537, antislip strip

571. Resilient end 2231, perforations 2232, stepped projections

2233. Guide surface 2233a, guide surface 3181, flat portion

3131 the leg 3211 secures the inner circumference of the pin 3212

3221 plane 3222 oblate hole 3223 spline tooth

Detailed Description

The utility model discloses among the preferred embodiment of power tool, power tool is the power screwdriver, can divide into pneumatic screwdriver, screwdriver and the electric screwdriver that surges according to the difference of power supply, also has the branch of direct current and interchange in the electric screwdriver, the utility model discloses preferably use direct current electric screwdriver to exemplify and carry out the concrete explanation.

Referring to fig. 1 to 3, the dc electric screwdriver includes a housing 1, a motor 2, a battery 6, a transmission mechanism 3, a connecting shaft 51, a working head support mechanism, and an output shaft 4. The casing 1 is assembled by two half shells of bilateral symmetry through the closure of screws (not shown), and it has horizontal part and the handle 11 part that is the obtuse angle K setting with the horizontal part, the utility model discloses preferred angle K is between 100 degrees to 130 degrees, and it can be more comfortable when holding handle 11 operation like this. A push button switch 7 is provided on the upper portion of the handle 11 portion, a battery 6 is fixed to the rear portion of the handle 11 portion, and a transmission mechanism 3 is accommodated in the horizontal portion of the housing 1. As a preferred embodiment, the battery 6 may be a lithium ion battery. It should be noted that the lithium ion battery referred to herein is a generic term of a rechargeable battery in which a negative electrode material is a lithium element, and may be constructed in many systems, such as a "lithium manganese" battery, a "lithium iron" battery, and the like, depending on a positive electrode material. In the present embodiment, the lithium ion battery is a lithium ion battery having a rated voltage of 3.6V (volts). Of course, the battery 6 may also be of a nickel cadmium, nickel hydrogen, or the like, of a type well known to those skilled in the art.

The transmission mechanism 3 includes, from back to front (rear on the right side of the drawing), a planetary gear reduction mechanism 31 driven by the motor 2 and a pinion mechanism 30, wherein the pinion mechanism 30 is connected to a connecting shaft 51, and transmits the rotational motion of the motor 2 to the output shaft 4 through the connecting shaft 51. The working head supporting mechanism is used for storing different working heads, the working heads mainly refer to cross screwdriver heads, straight screwdriver heads, drill heads and the like commonly used by electric screwdrivers, and different working heads can be quickly replaced when the electric screwdrivers tighten or loosen different screws by axially moving the connecting shaft 51 through the working head supporting mechanism or leaving the working head supporting mechanism and adjusting the position of the working head supporting mechanism.

According to the above constitution of the electric screwdriver, the electric screwdriver can be divided into a motor section D where a motor is provided, a transmission section C where a transmission mechanism 3 is provided, a storage section B where a storage clip is provided, and an output section a where an output shaft is provided, in this order from back to front (with the right side of the drawing as the back).

The motor 2 in the preferred embodiment of the present invention is an electric motor having a motor shaft 21 extending forwardly from a motor housing. The motor is fixed in the machine shell 1, a gear box 22 is fixed in the machine shell 1 and positioned at the front part of the motor, the gear box 22 is used for accommodating the planetary gear speed reducing mechanism 31 and the pinion mechanism 30, the planetary gear speed reducing mechanism 31 and the pinion mechanism 30 are separated by arranging a partition board 221 between the planetary gear speed reducing mechanism 31 and the pinion mechanism 30, and a gear box cover board 223 is arranged between the gear box 22 and the working head supporting mechanism, so that the transmission mechanism 3 and the working head supporting mechanism can be separated, namely, the transmission mechanism 3 and the working head supporting mechanism are independent. The pinion mechanism 30 includes a first gear 301 connected to the planetary gear speed reduction mechanism 31 via a gear shaft 308 in a torque transmittable manner, a third gear 303 connected to the connecting shaft 51, and a second gear 302 meshing with both the first gear 301 and the third gear 303, wherein the gear shaft 308 may be provided integrally with the first gear 301, and the second gear 302 transmits the rotation of the first gear 301 to the third gear 303, and both ends of each gear are supported by bushings. The middle part of the partition 221 is provided with a hole for the shaft of the first gear 301 to pass through, the end face of the partition 221 is provided with a groove for mounting a shaft sleeve, a rear shaft sleeve for supporting the pinion mechanism 30 is fixed on the partition 221, a front shaft sleeve is fixed on a gear box cover plate 223, and the gear box cover plate 223 is fixedly connected with the gear box 22 through screws, buckles and the like, so that the pinion mechanism 30 and the planetary gear speed reducing mechanism 31 can be separated and can be sealed at the same time, dust, powder and the like are prevented from entering the transmission mechanism 3, and the leakage of lubricating oil can also be prevented.

Referring to fig. 3, the center lines of the first gear 301, the second gear 302 and the third gear 303 are arranged on the same straight line, in order to make the transmission more stable, the transmission ratio from the first gear 301 to the third gear 303 is 1:1, so that the first gear 301 to the second gear 302 can be in speed-increasing transmission, the second gear 302 to the third gear 303 can be in speed-reducing transmission, if the reference circle diameters of the first gear 301 and the third gear 303 are equal, the reference circle diameter of the second gear 302 is smaller than the reference circle diameters of the first gear 301 and the third gear 303, the arrangement can ensure the optimal layout when the centers of the three gears are coaxial, and the occupied space is the minimum. However, if the electric screwdriver is relatively small, the second gear 302 may need to have a smaller number of teeth, which results in less teeth meshing with each other at the same time, and the strength of the transmission pair is reduced, which makes the transmission unstable. If the second gear 302 is eliminated and the first gear 301 and the third gear 303 are arranged to be directly meshed, the motion can also be transmitted, but the diameters of the first gear 301 and the third gear 303 must be increased, and the larger arrangement of the first gear 301 and the third gear 303 tends to increase the volume of the electric screwdriver. Therefore, referring to fig. 4, the second gear 302 can be eccentrically arranged relative to the connecting line of the rotation centers of the first gear 301 and the third gear 303, so that the size of the second gear 302 is not too small, and the size of the three gears in the parallel arrangement direction is not too large, so that the transmission among the three gears can be ensured to be relatively stable, the preferable eccentric size L is 0.1 to 0.3 times of the reference circle diameter of the first gear 301, and in addition, the reference circle diameter of the first gear 301 is 1.1 to 1.5 times of the reference circle diameter of the second gear 302, so that the high bearing capacity among the three gears is ensured, the efficiency is high, and the service life is long. In addition, the three gears can make the inner space of the tool more compact, so that the appearance of the outside is not influenced.

Of course, two gears may be provided as necessary, one being connected to the planetary gear speed reduction mechanism 31 and the other being connected to the connecting shaft 51. In addition, the transmission mechanism 3 is not limited to the above-described form, and the transmission mechanism 3 may include only the planetary gear speed reduction mechanism 31, or only the pinion gear mechanism 30, or other rotational motion transmission mechanisms such as a ratchet mechanism, a worm gear mechanism, and the like. The planetary gear reduction mechanism 31 has a three-stage reduction system, the motor shaft 21 extends to be meshed with the planetary gear reduction mechanism 31, the planetary gear reduction mechanism 31 transmits the rotation motion to the pinion mechanism 30, the pinion mechanism 30 drives the connecting shaft 51 to rotate, and the connecting shaft 51 drives the output shaft to rotate. When the motor 2 is operated, the output shaft 4 finally outputs the motor through the planetary gear reduction mechanism 31 and the pinion mechanism 30. It can be seen that the drive train in this embodiment is a motor-transmission-connecting shaft-output shaft, i.e. the connecting shaft is part of the drive train. In addition, the speed reducing mechanism is composed of a three-stage planetary speed reducing system and a two-stage parallel shaft speed reducing system to obtain the desired output speed, and in other embodiments, the speed reducing mechanism may only include a two-stage planetary speed reducing system or other speed reducing systems according to the required output speed.

Referring to fig. 5, 6, and 7, the planetary gear reduction mechanism 31 includes an output-side carrier 313. The electric screwdriver is provided with a self-locking device between the planetary gear speed reducing mechanism 31 and the pinion mechanism 30, the self-locking device comprises a fixed disc 321, a plurality of fixed pins 3211 are uniformly arranged on the outer side of the circumference of the fixed disc 321, the fixed pins 3211 are tightly connected with the gear box 22 into a whole, so that the fixed disc 321 is in a static state relative to the machine shell 1 and the gear box 22, and an inner circular surface 3212 is formed on the inner side of the circumference of the fixed disc 321. Within the inner circular surface 3212, an adapter 322 is disposed, and a flat square hole 3222 is disposed at a central portion of the adapter 322. One end of the gear shaft 308 is connected with the first gear 301, the other end is provided with a flat part 3181, and the adapter disc 322 and the gear shaft 308 are connected into a whole through the flat square hole 3222 and the flat part 3181, so that the adapter disc and the gear shaft 308 can rotate together. The connection used may be a spline connection as is customary to those skilled in the art and other connections are readily conceivable. The self-locking device further includes a plurality of support legs 3131 protruding from an end surface of the output end planet carrier 313 toward the first gear 301, and the support legs 3131 are fixedly disposed on the output end planet carrier 313.

A plurality of planes 3221 are formed on the outer side of the circumference of the adapter disc 322, a connecting portion is arranged at one end, close to the output end planet carrier 313, of the adapter disc 322, the connecting portion adopts spline teeth 3223, and the adapter disc 322 is loosely matched with the output end planet carrier 313 through the spline teeth 3223. A roller 323 is respectively arranged between the fixed disc 321 and the adapter disc 322, and more particularly, between the inner circle surface 3212 of the fixed disc 321 and the plane 3221 of the adapter disc 322, and the roller 323 abuts against the inner circle surface 3212 and the plane 3221 and can roll on the position. In addition, a leg 3131 of the output side carrier 313 is interposed between each of the rollers 323, that is, the leg 3131 is disposed between the inner circular surface 3212 of the fixed disk 321 and the outer circular surface of the adaptor disk 322. The supporting leg 3131 is in clearance fit with both the inner circumferential surface 3212 of the fixing disk 321 and the adaptor disk 322, so that the supporting leg 3131 can rotate around the center of the adaptor disk 322.

Referring to fig. 8, when the push button switch 7 is triggered, taking the rotation output of the motor 2 in the counterclockwise direction as an example, the rotation torque generated by the motor 2 is transmitted to the output end planet carrier 313, and the output end planet carrier 313 rotates a certain angle relative to the adapter 322 in spline connection with the output end planet carrier 313, at this time, the support leg 3131 of the output end planet carrier rotates along with the output end planet carrier 313 in the corresponding direction. When the supporting leg 3131 rotates for a small displacement, it abuts against the roller 323, and since the roller 323 moves from the small end to the large end of the wedge surface formed between the inner circular surface 3212 and the plane 3221 of the adapter 322, the roller 323 can be pushed by the supporting leg 3131 of the output end planet carrier to rotate along with the output end planet carrier 313 until the output end planet carrier 313 contacts with the side surface of the spline 3223 of the adapter 322, and at this time, the supporting leg 3131 of the output end planet carrier and the roller 323 drive the adapter 322 to rotate together. In this way, the rotation torque of the motor 2 is transmitted to the gear shaft 308 fixedly connected to the adapter plate 322, and further transmitted to the first gear 301, and transmitted to the output shaft 4 through the second gear 302, the third gear 303 and the connecting shaft 51, so that the output shaft 4 drives the working head 9 to rotate.

With further reference to fig. 9, when the push switch 7 is turned off, the motor 2 stops rotating without a rotational torque output. At this time, no matter the operator twists the output shaft 4 or the working head 9 accommodated in the output shaft 4 in the clockwise direction or the counterclockwise direction, it is shown that the gear shaft 308 slightly rotates along with the corresponding direction, and since the gear shaft 308 and the adapter disc 322 are connected into a whole through the flat square, the adapter disc 322 also rotates along with the gear shaft 308 in the corresponding direction. And the roller 323 rolls from the position shown by the dotted line to the position shown by the solid line, because the roller 323 moves from the large end to the small end of the wedge surface formed between the inner circular surface 3212 and the plane 3221 of the adapter disc 322, at this time, the plane 3221 of the fixed disc 321, the inner circular surface 3212, and the plane 3221 of the adapter disc 322 are wedged tightly with each other, the gear shaft 308 cannot drive the output end planet carrier support 41 to rotate, that is, the gear shaft 308 is automatically locked, that is, the rotational motion cannot be transmitted from the output shaft 4 to the output end planet carrier 313. Due to the arrangement of the self-locking structure, an operator can select to manually rotate the electric screwdriver to screw the screw. The electric screwdriver is particularly suitable for stopping the motor 2 through the button switch 7 under the condition that the electric screwdriver is used for screwing the screw to be basically in place in the electric mode, and rotating the electric screwdriver to screw the screw to be in place in the manual mode, so that the phenomenon that the screw is over-screwed in the electric mode to cause the screw to be slipped out of teeth is avoided. The electric screwdriver is a screwdriver integrating hand operation and electric operation, and is convenient to operate and carry.

While the self-locking device is disposed between the planetary gear reduction mechanism 31 and the pinion gear mechanism 30 in the above-mentioned embodiment, it is easy for those skilled in the art to think that the self-locking device is disposed at other positions between the motor 2 and the output shaft 4 to realize the unidirectional transmission of the motor 2 to the output shaft 4, such as between the motor 2 and the planetary gear reduction mechanism 31, between the pinion gear mechanism 30 and between the connecting shaft 51, etc. The structural style of the self-locking device is not limited to the above embodiment, and any self-locking device capable of realizing one-way transmission can be applied to the preferred electric screwdriver of the utility model.

The casing 1 is slidably connected with a sliding cover 53, and the sliding cover 53 can drive the connecting shaft 51 to move axially. The edge of the sliding cover 53 is provided with a guide track 531, and correspondingly, the housing 1 is provided with a guide groove 15, and the sliding cover 53 is installed in the guide groove 15 through the guide track 531 and can slide axially relative to the housing 1. Of course, the sliding cover 53 may be provided with a guide groove, and the sliding cover 53 may be moved by providing a guide rail on the housing 1.

The section of the handle part of the common standard working head is in a regular hexagon shape, namely the handle part forms a torque stress part of the working head, the output shaft 4 is provided with an axially penetrating accommodating hole 41, the accommodating hole 41 is arranged in a hexagonal hole form matched with the torque stress part of the working head, and the working head is arranged in the accommodating hole to enable the working head to be in a working position, so that the torque transmission is realized. Of course, the working head may be non-standard, that is, the cross section of the torque bearing part is polygonal, and the corresponding receiving hole is set to be polygonal matched with the torque bearing part, so that the torque transmission can be realized. The output shaft 4 is supported in the axial opening 131 of the front housing 13 by a bushing 40. the bushing 40 provides radial support for the output shaft 4, although radial support of the output shaft 4 may be provided by bearings. The utility model discloses a connecting axle 51 also is the hexagon, is equipped with the hexagonal hole in the third gear 303 for join in marriage with connecting axle 51 and join in marriage rotatory power transmission and give connecting axle 51, connecting axle 51 inserts output shaft 4 like this and can drive output shaft 4 rotatory, and then drives working head 9 through output shaft 4 and rotate, can use standard's working head 9 like this, need not to set up the hole of acceping working head 9 on connecting axle 51 in addition, avoids the weight and the volume of connecting axle 51 diameter too big increase complete machine. Therefore, the working head 9 is directly driven to rotate to form an output shaft, the torque transmission distance is shortened, and the tool is more reliable to use. However, it is easy for those skilled in the art to substitute other transmission methods, for example, the connecting shaft directly drives the working head to rotate, that is, the connecting shaft is directly connected to the working head in a manner of transmitting torque, or the output shaft is directly driven by a gear, and the connecting shaft is only used for pushing out the working head and driving the working head to return to the storage clip, that is, the transmission chain is a motor-transmission mechanism-output shaft, that is, the connecting shaft does not serve as a part of the transmission chain.

Referring to fig. 1, 2, 5 and 6, the connecting shaft 51 is a hexagonal shaft, a fixing block 50 is axially fixed on the connecting shaft 51, and the sliding cover 53 can drive the connecting shaft 51 to move by connecting with the fixing block 50. The inside of the sliding cover 53 is provided with a first bump 535 and a second bump 536 at an interval along the axial direction of the connecting shaft 51, in the working state of the electric screwdriver, the first bump 535 and the fixed block 50 have a distance S at an interval along the axial direction, when the sliding cover 53 slides backwards, i.e. slides towards the direction of the motor 2, and after the distance S is slid, the first bump 535 and the fixed block 50 are axially abutted, so that the sliding cover 53 drives the fixed block 50 to drive the connecting shaft 51 to axially move backwards, otherwise, the second bump 536 drives the connecting shaft 51 to axially move forwards. In addition, when the electric screwdriver is operated, the working head 9 needs to be axially abutted against a screw or a workpiece, so that the working head 9 can be acted by a reverse axial force and can generate backward movement of the connecting shaft 51.

The fixed block 50 is a square hollow shape, the connecting shaft 51 is provided with a supporting end 512 connected with the fixed block 50, the supporting end 512 is arranged to be cylindrical, a round hole or a U-shaped hole is formed in one side edge of the fixed block 50, the supporting end 512 is rotatably supported on the fixed block 50 through the round hole and the U-shaped hole, and the supporting end 512 extends into the hollow part of the fixed block 50 and can be provided with an annular groove so that a retainer ring can be assembled to limit the axial movement of the connecting shaft 51. The diameter of the support end 512 is preferably smaller than the diameter of the circle circumscribing the hexagon of the connecting shaft 51, so that the volume of the fixing block 50 can be reduced and the overall structure of the tool can be more compact. The other side edge, opposite to the round hole or the U-shaped hole, of the fixing block 50 abuts against the end portion of the supporting end 512, wherein the end portion of the supporting end 512 is arranged in a conical shape, so that the connecting shaft 51 is in point contact with the fixing block 50, because the electric screwdriver needs to axially abut against the working head 9 on a workpiece when in operation, the working head 9 can be acted by a reverse axial force, the axial force can be transmitted to the connecting shaft 51, large forced friction can be generated between the connecting shaft 51 and the fixing block 50, the friction can be reduced by means of point contact, and the service life of the connecting shaft 51 is prolonged. In addition, the connecting shaft 51 and the fixing block 50 can be made of metal, so that the abrasion degree between the connecting shaft 51 and the fixing block 50 is reduced. Also, the fixing block 50 may be connected by a plurality of square hollow shapes to increase strength, and two or three square hollow shapes are preferably used as in the present embodiment. The fixed block 50 can also have other advantages, such as that the connecting shaft 51 can be rotatably supported on the fixed block 50 without using a bearing for supporting, thereby reducing the volume and cost of the tool; the area of the side part of the fixed block 50 is large, so that the limit block 81 is convenient to abut against the fixed block 50 to limit the connecting shaft 51 axially, and the sliding cover 53 is also convenient to drive the connecting shaft 51 to move in an abutting manner with the fixed block 50; the hollow part of the fixing block 50 can also play a role in the sliding cover 53 having an idle stroke relative to the connecting shaft 51 (i.e., the sliding cover 53 moves without the connecting shaft 51 moving), so that the sliding cover 53 only needs to be provided with a bump to drive the connecting shaft 51 to move back and forth, thereby facilitating the sliding cover 53 to operate the limiting block 81 to lock and unlock the connecting shaft 51.

In addition, as will be readily understood by those skilled in the art, if the transmission chain of the power screwdriver does not include a connecting shaft, that is, the output shaft is directly driven to rotate by the pinion mechanism, then there will be relative rotation between the working head and the connecting shaft, and friction will inevitably be generated, so that the friction can be reduced as long as a point contact is formed between the working end of the connecting shaft provided with the magnet and the working head, and the service life of the tool can be prolonged.

Of course, there are many ways for the sliding cover 53 to drive the connecting shaft 51 to move, for example, a ring groove surrounding the periphery of the connecting shaft 51 may be provided on the connecting shaft 51, and the sliding cover 53 extends into the ring groove through a pin or a wire ring to connect with the connecting shaft 51, so that the rotation of the connecting shaft 51 is not affected, and the sliding cover 53 drives the connecting shaft 51 to move is also not affected. The front end of the connecting shaft 51 is provided with a magnet 511 for attracting the working head 9, when the working head 9 is selected, the sliding cover 53 can be operated to drive the connecting shaft 51 to pass through the working head supporting mechanism, the working head 9 is attracted by the magnet 511 on the connecting shaft 51, and leaves the working head supporting mechanism under the pushing of the connecting shaft 51 to enter the output shaft 4.

The housing 1 includes a front case 13 connected to a front end thereof, and a part of the working head support mechanism is housed in the front case 13 and the other part is covered by the slide cover 53 and exposed as the slide cover 53 moves. The utility model discloses preferred working head supporting mechanism is cylindric storage clip 52, and convenient the rotation, occupation space is little simultaneously, can set to square, triangle-shaped, banding certainly, support form etc.. When the electric screwdriver is operated, the sliding cover 53 abuts against the front housing 13, so that the storage clip 52 and the connecting shaft 51 can be closed. The gear box cover plate 223 is provided with a hole for the connecting shaft 51 to pass through, the gear box 22 extends around the axis of the connecting shaft 51 to form an arch 225, the arch 225 can be integrally or separately arranged with the gear box 22, the connecting shaft 51 can be partially sealed by the arrangement of the arch 225, when the working head 9 of the electric screwdriver is replaced, namely the sliding cover 53 moves to the rearmost position, the connecting shaft 51 cannot be exposed, and therefore dust, powder and the like can be prevented from entering the tool. Furthermore, the gearbox cover 223 extends to the end face of the arch 225, so that the transmission 3 is closed together in its entirety in the axial direction. In the working process, the sliding cover 53 can seal the storage clip, so that dust is prevented from entering, when the working head needs to be replaced, the sliding cover 53 is removed to expose the storage clip 52, different working heads are convenient to select, and thus the sliding cover 53 needs to have a certain length, when the sliding cover 53 moves to the working position abutted against the front shell 13, the sliding cover 53 is axially overlapped with the storage part B and the transmission part C, and when the sliding cover 53 moves to the position where the working head can be replaced, the sliding cover 53 is axially overlapped with the motor part D and is partially axially overlapped with the transmission part C. Of course, there are many ways to move the sliding cover 53, for example, the sliding cover 53 can be rotatably installed on the housing 1, and can rotate between two positions for covering the storage clip 52 and exposing the storage clip 52; or may be opened or closed in a manner similar to a sliding door; or pivotally connected to the housing 1, etc., to close the storage clamp 52 during operation and expose the storage clamp 52 when the working head needs to be replaced.

The upper part of the front shell 13 is provided with an opening part 133, the bottom of the front shell 13 is provided with a radial opening 134 which is opposite to the opening part 133 in the radial direction, the sliding cover 53 is operated to move towards the direction of the motor 2, the connecting shaft 51 moves to a position separated from the storage clamp 52 along with the sliding cover 53, so that the storage clamp 52 can be ejected out of the opening part 133 and removed by directly extending fingers into the radial opening 134, and then another storage clamp provided with a different working head is installed into the machine shell from the opening part 133 for use.

The storage clamp 52 is rotatably supported between the gear box cover plate 223 and the output shaft 4, a plurality of working head accommodating chambers 521 are uniformly distributed on the storage clamp 52 along the circumferential direction, that is, the working heads have a plurality of accommodating spaces, and the plurality of accommodating spaces are arranged in parallel along the rotation axis of the storage clamp 52. The working head accommodating bin 521 is partially closed along the axial direction of the storage clamp 52, and partially opened at the outer circumference, so that an operator can easily see the shape of the head of the working head 9 from the opened part when selecting the working head 9, and the operator can quickly select the required working head 9. Of course, it is easy for those skilled in the art to understand that the working head storage bin 521 can also be fully enclosed, and only the corresponding position needs to be marked, or the storage clip 52 can be made transparent directly, so that the identification can be facilitated. In addition, elastic positioning can be performed between the storage clamp 52 and the gear box cover plate 223, that is, a positioning groove 522 is arranged at a position, corresponding to the working head 9, on the end surface of the storage clamp 52 facing the gear box cover plate 223, the positioning groove 522 corresponds to the accommodating bin 521, and a steel cap or a spring plate pressed by a spring is arranged on the gear box cover plate 223, so that a prompt sound falling into the positioning groove 522 is given out when the storage clamp rotates one working head 9, and an operator can avoid the rotation angle of the storage clamp 52 from being staggered with the connecting shaft 51 when selecting the working head 9.

When the electric screwdriver needs to work, the connecting shaft 51 moves forwards under the driving of the sliding cover 53 to push the selected working head to enter the output shaft 4, when the working head needs to be replaced, the connecting shaft 51 moves backwards under the driving of the sliding cover 53, and because the magnet 511 is arranged at the end, in contact with the working head, of the connecting shaft 51, the connecting shaft 51 can drive the working head to return to the accommodating bin 521 of the working head storage clamp. If the connecting shaft 51 continues to move backwards, the working head is driven to come out of the accommodating bin 521, so that the working head cannot be replaced, and if an operator does not find that the storage clamp is rotated, the tool is likely to be damaged. The present invention proposes four solutions to solve this problem, which are explained below.

Referring to fig. 2 and 10 to 12, a first embodiment for limiting the backward movement of the working head 9 with the connecting shaft 51 is shown. The end of the storage clip 52 facing the gear housing 22 is provided with a pressure plate 522, the pressure plate 522 can rotate along with the storage clip 52, the pressure plate 522 can be arranged integrally with the storage clip 52 or separately, and the embodiment is preferably arranged separately, which is convenient for processing and easy for assembling. The pressing plate 522 is provided with an opening 523 corresponding to the accommodating bin 521 for passing through the connecting shaft 51, a U-shaped groove 526 is arranged on the end surface of the opening 523 facing the storage clamp and used for accommodating the U-shaped spring 56, part of the U-shaped spring 56 is overlapped with the opening 523 in a free state, and the design of the U-shaped groove 526 reserves a space for elastic deformation of the U-shaped spring 56. Since the number of the accommodating chambers 521 of the present invention is preferably 6, the number of the corresponding openings 523 is also 6, and the number of the U-shaped grooves 526 and the U-shaped springs 56 is also 6, it is obvious to those skilled in the art that only one opening 523, one U-shaped groove 526 and one U-shaped spring 56 may be provided, that is, the pressing plate 522 is fixedly disposed relative to the gear box 22, so that the same opening 523 is passed through by the connecting shaft 51 each time, and the rotating storage clamp 52 is not affected to select a working head. When the connecting shaft 51 is retracted and moves backward with the working head under the action of the magnet 511, the U-shaped spring 56 is elastically deformed and caught on the connecting shaft 51, that is, the U-shaped spring 56 is in the first position allowing the connecting shaft 51 to move (refer to fig. 13). Because the end of the connecting shaft 51 connected with the working head and the end of the working head connected with the connecting shaft 51 are both chamfered or rounded, when the end of the connecting shaft 51 connected with the working head 9 leaves the opening 523 of the pressing plate 522, the U-shaped spring 56 returns to a free state to block part of the opening 522, and the working head 9 is blocked by the U-shaped spring 56 as the connecting shaft 51 continues to retreat, that is, the U-shaped spring 56 is in the second position for limiting the retreat of the working head 9 (refer to fig. 14). Thus, the connecting shaft 51 is separated from the working heads 9, and the storage clamp can be rotated arbitrarily to select another working head 9 as desired. In order to prevent the U-shaped spring 56 from causing resistance to the rotation of the connecting shaft 51 when the power screwdriver is in operation, an annular groove 512 surrounding the connecting shaft 51 for a circle may be provided on the connecting shaft 51 at a position axially corresponding to the U-shaped spring 56, so that the U-shaped spring 56 does not cause resistance to the rotation of the connecting shaft 51, and the U-shaped spring 56 guides the working head back into the storage clamp 52.

Referring to fig. 13 to 15, a second embodiment for limiting the backward movement of the working head 9 with the connecting shaft 51 is shown. An elastic sheet 57 is fixed on the gear box cover plate 223, the elastic sheet 57 is arranged between the storage clamp 52 and the gear box cover plate 223, at least one elastic tail end 571 is arranged on the elastic sheet 57, and the elastic tail end 571 partially extends into a hole in the gear box cover plate 223, so that the working head 9 can be clamped through elastic deformation of the elastic tail end 571, and the working head 9 is prevented from leaving the storage clamp 52 when the connecting shaft 51 retreats. Referring to fig. 14, the resilient tip 571 is in a first position allowing movement of the connection shaft 51; referring to fig. 15, the resilient tip 571 is in a second position that limits the working head 9 from retracting. According to the present embodiment, it is easy for those skilled in the art to think that the elastic tip 571 can be directly clamped on the gear box cover plate 223, or a rigid fixing piece can be provided, which can move between two positions of partially shielding the hole on the gear box cover plate 223 and leaving the hole on the gear box cover plate 223 through the elastic action, thereby achieving the separation between the working head 9 and the connecting shaft 51 and guiding the working head 9 back to the storage clip 52.

Referring to fig. 16, a third embodiment for limiting the backward movement of the working head with the connecting shaft is shown. A through hole 2231 is formed in the gear box cover plate 223 corresponding to the connecting shaft 51, a step protrusion 2232 is formed on the end surface of the gear box cover plate 223 adjacent to the storage clip 52, the step protrusion 2232 surrounds the rotation center of the storage clip 52 and is arranged corresponding to the storage bin 521, the step protrusion 2232 is broken at the through hole 2231, guide surfaces 2233 are arranged on the portions, located on the two sides of the through hole, of the step protrusion 2232, the height of the guide surfaces 2233 increases progressively from the through hole 2231 along the direction of the working head rotating along with the storage clip, that is, the height of the guide surfaces 2233 increases progressively from the through hole 2231 to the two sides, so that two guide surfaces are formed, and the position of the working head can be guided no matter whether the storage clip 52.

Referring to fig. 17, a fourth embodiment for limiting the backward movement of the working head with the connecting shaft is shown. The guide surface 2233a is directly arranged on the end surface of the gear box cover plate 223, the guide surface 2233a is arranged around the through hole 2231, and the height of the guide surface 2233a increases progressively from the through hole 2231 to the outside, so that an annular guide surface 2233a is formed, which is beneficial to processing and can ensure that the position of the working head can be guided when the storage clamp rotates forwards and backwards.

When separating the working head from the connecting shaft 51 and guiding the working head 9 back to the storage clip 52 in the third and fourth embodiments as described above, the guide surfaces function the same, taking the third embodiment as an example, the specific operation principle of the guide surface 2233 is shown in fig. 18 to 20, when the working head needs to be replaced, the sliding cover 53 is operated to drive the connecting shaft 51 to move until the connecting shaft 51 is separated from the storage clamp 52 along the axial direction (i.e. the axial direction is not overlapped), the working head is still jointed with the connecting shaft 51 under the suction force of the magnet 511 on the connecting shaft 51 and partially exceeds the end surface of the storage clamp 52, the storage clamp 52 is rotated, the working head moves along with the storage clamp 52 and is abutted against the guide surface 2233, thus, when the storage clip 52 is rotated, the working head 9 slides to the position where the end surface of the working head 9 is flush with the end surface of the storage clip 52 by the guide surface 2233, and the rotation of the storage clip 52 is not affected.

Although the storage clip 52 can be normally rotated if the stroke of the movement of the connecting shaft 51 and the dimensional accuracy and the assembly accuracy of the storage clip 52 and the internal structure of the tool are set, the connecting shaft 51 can only drive the working head 9 to move to the position where the end surface of the working head is flush with the end surface of the storage clip 52, in this way, the high requirements on the processing accuracy and the assembly accuracy of parts are required, the cost of the electric screwdriver is increased, and the dimension between the parts generates errors along with continuous friction in use, and the storage clip 52 is still clamped by the working head 9 or the storage clip 52 is clamped by the connecting shaft 51, so that the storage clip 52 cannot normally rotate. It is also considered that the working head and the gear case cover plate 223, the connecting shaft 51 and the storage clamp 52 may interfere in the rotation process under the influence of comprehensive factors such as manufacturing precision, shaking clearance, materials and the like. By providing a guide surface, a large margin is left for the movement of the connecting shaft 51, so that the geometry at the fitting location is improved, and the possibility of interference of various parts during the rotation of the storage clamp 52 is eliminated. This reduces costs significantly without requiring high manufacturing and assembly accuracy, and the storage clip 52 is less likely to become jammed and thus increases the useful life of the tool.

According to the principle of movement between the working head 9 and the guide surface 2233, the guide surface 2233 may be an inclined surface, a curved surface, an arc surface, etc., in this embodiment, an inclined surface is preferred, the inclined surface has an inclination angle α relative to the end surface of the storage clamp 52, the length of the inclined surface is approximately multiplied by sin α, so that the larger the angle α is, the larger the movement margin of the connecting shaft 51 is, the larger the force required for rotating the storage clamp 52 to drive the working head 9 to move along the inclined surface is, and in order to balance the two relatively, the inclination angle α of the inclined surface is preferably between 10 degrees and 30 degrees, so that the storage clamp 52 does not need to be rotated by a large amount of force, and the sufficient movement margin of the connecting shaft 51 is ensured.

The above definitions of the various elements are not limited to the various specific configurations or shapes mentioned in the embodiments, and may be easily and commonly replaced by those skilled in the art. For example, the motor can be a gasoline engine or a diesel engine and the like to replace the motor; the working head can be a polygon with any regular cross section; in addition, in the above embodiment, the relative axial movement between the connecting shaft and the working head storage clamp may be fixing of the connecting shaft, while the working head storage clamp can move axially and rotate, and the connecting shaft may be coaxial with the motor shaft.

Claims

1. A power tool, comprising:

a housing;

a motor disposed in the housing and outputting rotational power;

the output shaft is provided with an accommodating hole which is axially arranged and used for accommodating the working head;

the transmission mechanism is arranged between the motor and the output shaft and can transmit the rotary power output by the motor to the output shaft;

the working head supporting mechanism is arranged in the shell and provided with a plurality of accommodating spaces which are used for supporting the working heads and are arranged in parallel, and the working head supporting mechanism can be adjusted to a position where one accommodating space axially corresponds to the output shaft;

the connecting shaft is arranged in the machine shell and can move between two positions to drive the working head to be positioned at a working position in the accommodating hole or at an accommodating position of the working head supporting mechanism;

the method is characterized in that: the transmission mechanism comprises a self-locking device, and the self-locking device is used for transmitting the rotating power of the motor to the output shaft in a one-way mode.

2. The power tool of claim 1, wherein: the transmission mechanism comprises a planetary gear speed reducing mechanism driven by a motor and a gear mechanism driven by the planetary gear speed reducing mechanism, and the self-locking device is arranged between the planetary gear speed reducing mechanism and the gear mechanism.

3. The power tool of claim 2, wherein: the self-locking device comprises an adapter disc connected with the gear reduction mechanism and used for driving the gear mechanism, a fixed disc fixedly connected relative to the shell, and an intermediate transmission mechanism used for connecting the adapter disc and the fixed disc to realize one-way transmission.

4. The power tool of claim 3, wherein: the planetary gear speed reducing mechanism comprises an output end planet carrier, an external spline is arranged on the switching disc, and the external spline is connected with an internal spline arranged on the output end planet carrier.

5. The power tool of claim 4, wherein: the external spline and the internal spline are in loose fit along the circumferential direction.

6. The power tool of claim 4, wherein: the middle transfer mechanism comprises at least one plane arranged on the outer surface of the adapter disc along the circumferential direction, an inner circular surface of the fixed disc and at least one roller positioned between the plane and the inner circular surface of the fixed disc.

7. The power tool of claim 6, wherein: the output end planet carrier comprises a plurality of support legs extending between the plane and the inner circular surface, and the roller is positioned between two adjacent support legs.

8. The power tool of claim 3, wherein: the outer surface of the fixed disc is provided with a bulge for fixedly connecting with the shell.

9. The power tool of claim 2, wherein: the gear mechanism includes a first gear connected to the planetary gear reduction mechanism, a third gear for driving the output shaft, and a second gear simultaneously engaged with the first gear and the third gear.

10. The power tool of claim 1, wherein: the connecting shaft is connected between the transmission mechanism and the output shaft, and the transmission mechanism transmits the rotary power output by the motor to the output shaft through the connecting shaft.