WO2019105097A1

WO2019105097A1 - Precise electric screwdriver

Info

Publication number: WO2019105097A1
Application number: PCT/CN2018/104553
Authority: WO
Inventors: 龙军
Original assignee: 苏州多维思智能科技有限公司
Priority date: 2017-11-29
Filing date: 2018-09-07
Publication date: 2019-06-06

Abstract

A precise electric screwdriver, comprising a screwdriver bit and a housing (1). A motor (2) is provided in the housing (1); the screwdriver bit is positioned in front of the housing (1); a composite mechanism for implementing switching between manual and automatic modes is provided between the screwdriver bit and the motor (2); the proximal end (42) of an output shaft (4) of the composite mechanism is a step having a larger diameter than the distal end (41); the peripheral surface of the step is formed by a group of curved surfaces; the group of curved surfaces are formed by connecting outer convex surfaces (43) and inner concave surfaces (44) spaced from each other.

Description

Precision electric screwdriver

Technical field

The invention relates to a screwdriver, in particular to a screwdriver for tightening and unscrewing a screw and a nut, and integrating the manual and the automatic.

Background technique

A screwdriver is a tool used to twist a screw to force it into place. Usually, the screwdriver is divided into a common screwdriver, a combination screwdriver, and an electric screwdriver. The electric screwdriver is generally a combined screwdriver. Electric screwdrivers, as the name suggests, replace the manual installation and removal of screws with electric motors. Conventional small electric screwdrivers cannot be used manually without power. When used manually, the output shaft of the screwdriver is active and unlocked.

In the prior art, a hand-in-one screwdriver is also used, which adopts a one-way valve to limit the position, and realizes the manual integration. The one-way valve has a large volume and a large outer diameter, so that the volume of the screwdriver product and The outer diameter is also large, which is not convenient to carry and store. The Chinese patent CN 201410339537.0 improves the technology of hand-integration and adopts a composite mechanism comprising an output shaft, a support frame, a bearing seat and a plurality of pins which cooperate with each other. However: (1) the parts in the composite mechanism are relatively shaped, and the production cost is relatively large, especially the three-stage output shaft, which also leads to a longer overall length of the screwdriver; (2) the torque of the composite mechanism is small; 3) In the switching manual mode, the rotation of the output shaft has a long period of idle travel, and the user experience is not good; (4) the support frame and the housing are connected by sliding, if the two are close Contact will produce sliding friction, which will result in a loss of relatively large power. There will be noise when the screwdriver is used for a long time. However, if the two do not touch, the support frame will produce a certain sway when it is rotated, then: a, the user experience is not good, the feeling of hand tremor is serious; b, the whole batch of the screwdriver has been shaking for a long time, for the motor and the circuit The connection also has a relatively large hidden danger; c. Its single cylindrical outer casing also imposes high assembly requirements for the assembly of the internal mechanism; d, the noise generated by the motor can also be ignored.

Chinese patent CN 201410339624.6 also discloses an electric screwdriver with the same composite output mechanism, and the same composite output mechanism has the above technical problems. The difference is that the patent uses the integrated tubular casing of the original screwdriver and the motor casing to adopt the structure of the assembled casing, and is improved to adopt a mounting inner casing, which is assembled by the first one. The mounting shell and the second mounting shell are composed of a geared motor, a switch, a battery and a composite output mechanism. The structural form can achieve convenient and quick technical effects, but this also brings some problems: a. Due to the artificial addition of an inner casing, the cost will be greatly increased; b, the battery and other electrical components are connected by wires, and the wires need to be welded first and then placed in the installation. In the case, there is a problem that the wire arrangement is time-consuming and labor-intensive during assembly, and in many cases, the pressure line may cause the assembly to be unsatisfactory, or the assembly worker may inadvertently contact the wire with the battery or the electrical component. The assembly accident of the broken solder joint. This situation is not allowed in the assembly, which will lead to a significant increase in product defect rate.

Summary of the invention

The object of the present invention is to solve the above technical problems and to provide an ultra-quiet precision electric screwdriver of better use and high stability.

The invention is achieved by the following technical solutions:

A precision electric screwdriver, comprising a screwdriver bit and a casing, wherein the casing is provided with a motor, the screwdriver bit is located in front of the casing, and the screwdriver bit and the motor are provided for manual operation. And a composite mechanism for automatic mode switching, the composite mechanism comprising:

a bearing housing including a stepped inner cavity and fixed to the housing

An output shaft interposed in the inner cavity of the bearing housing and having a distal end extending from a distal end of the bearing housing, the distal end of the output shaft having a hexagon socket for receiving the screwdriver bit, The proximal end of the output shaft is a step having a diameter larger than a distal end thereof, the step being matched with a stepped inner cavity of the bearing seat, the outer peripheral surface of the step being formed by a set of curved surfaces, the set of curved surfaces being spaced apart from each other The convex surface and the concave surface are connected,

And a rotating frame and a plurality of rollers disposed between the bearing housing and the output shaft, the rotating frame cooperates with the roller to drive the output shaft to realize an automatic mode of the precision electric screwdriver, the roller will be The output shaft and the bearing housing are fixed to each other to realize the manual mode of the precision electric screwdriver.

Preferably, the rotating frame comprises a back plate and a plurality of extending arms extending vertically, and the backing plate is provided with a linking shaft hole that is opposite to the shaft of the motor, so that the rotating frame and the motor are arranged The shaft is coupled, the extension arm extends between the proximal end of the output shaft and the bearing housing, the inner diameter of the extension arm is equivalent to the outer diameter of the outer convex surface, and the roller is axially disposed on the rotation Between the back plate of the frame and the stepped inner cavity of the bearing housing, circumferentially disposed between the inner concave surface and the bearing seat, and between the adjacent extending arms, the diameter of the roller is larger than the outer convex surface The distance between the bearing seats and the maximum distance between the inner concave surface and the bearing housing.

Preferably, in the automatic mode, the roller generates an oblique force in a rotational direction to the output shaft.

Preferably, the diameter of the roller is equal to the maximum distance between the concave surface and the bearing housing.

Preferably, a bracket is fixed in the housing, the motor is fixed inside the bracket, the composite output mechanism is located at a distal end of the bracket, and a battery is disposed at a proximal end of the bracket, and the bracket is also fixed There is a circuit board electrically connected to the positive and negative poles of the battery.

Preferably, the bracket comprises an annular body and two supporting pieces which are symmetric with each other and extend proximally along the axis of the bracket; the outer circumference of the annular body is provided with a protrusion for being inside the housing The grooves are matched to each other so that the two are radially fixed to each other; the distal end faces of the annular bodies cooperate with the projections in the housing to axially fix the two.

Preferably, the proximal end of the annular body of the bracket is further provided with an inward convex wall, and a wedge block disposed on the support piece cooperates to fix the motor axially inside the bracket. The flat surface of the motor cooperates with the inner surface of the leg to radially fix the motor to the bracket.

Preferably, the circuit board is fixed to the bracket by screws, and a first end thereof is located at a proximal end of the motor; and a second end of the circuit board includes positive and negative pole contacts of the battery, wherein a positive pole The contacts are in direct contact with the battery through the bayonet of the proximal end of the tab, and the negative contact is electrically coupled to the conductive barrel and/or the conductive spring at the proximal end of the battery.

Preferably, the housing is provided with two through holes, and two switch buttons respectively pass through the through holes to press the switch contacts of the circuit board, and the two ends of the switch buttons are respectively provided with barbs And for preventing the switch button from falling out of the through hole.

Preferably, an anti-friction pad is further disposed between the rotating frame and the bracket, and the anti-friction pad is sleeved outside the motor shaft of the motor.

Preferably, the bearing housing is fixed to the bracket by a shoulder.

In another aspect, the housing is a cylindrical structure having a receiving space formed by the first housing and the second housing being fixed together by a snap mechanism.

Preferably, the bearing housing is fixed to the housing by a shoulder.

Preferably, an anti-friction pad is further disposed between the bearing seat and the housing, and the anti-friction pad is sleeved outside the motor shaft of the motor.

Preferably, the housing is further provided with a battery and a circuit board provided with a switch, the housing is provided with a switch button for controlling the switch, and a non-slip sleeve sleeved outside the housing; the shell The front end of the body is respectively provided with a front locking sleeve and a rear locking sleeve; the rear locking sleeve is disposed between the tail cover and the housing, the tail cover is screwed with the housing, and the front locking sleeve is inside LED light pipe and lampshade are provided.

Preferably, a sealing ring is disposed between the bearing housing and the output shaft for forming a closed space between the bearing housing and the proximal end of the output shaft.

Preferably, the distal end of the output shaft is flush with the distal end of the bearing housing.

Preferably, the distal end of the output shaft has a hexagon socket for receiving the screwdriver bit and has a magnet inside.

The beneficial effects of the present invention are mainly embodied in:

1. In the automatic mode, the roller of the present invention generates an oblique thrust in the direction of rotation of the output shaft, so that the torque of the precision electric screwdriver of the present invention is increased;

2. In the manual mode, the output shaft of the present invention does not substantially generate a rotating idle stroke, and the user experience is good;

3. The special-shaped structure of the output shaft is eliminated, which makes the manufacturing more convenient, and the overall length of the precision electric screwdriver of the invention can be shortened and the cost is reduced;

4, the bracket is set, the electrical components in the housing can be installed and positioned on the mechanism first, and then the welding electrical connection is realized, so that the electrical connection is more reliable and simple, and there is no hidden danger of leakage and power failure;

5, the bracket setting, can also be used directly as a welding fixture, no need to set aside;

6. The distal end of the output shaft is flush with the distal end of the bearing housing, so that the mating length of the two is greatly increased, the stability of the transmission is improved, and the hand tremor feeling brought by the prior art is reduced, and the drop is achieved. The purpose of noise;

7. The cylindrical shape structure of the output shaft is more compact and the cost is lower;

8. The setting of the friction reducing pad can reduce the friction between the rotating frame and the housing, improve the driving efficiency and reduce the energy consumption;

9. The sealing ring on the outer side of the output shaft can form a closed space between the bearing seat and the proximal end of the output shaft, and the lubricating oil placed in the space can greatly increase the mute effect of the entire screwdriver.

DRAWINGS

Figure 1 is a schematic exploded view of a preferred embodiment of the present invention;

Figure 2 is a front elevational view of a preferred embodiment of the present invention;

Figure 3 is an enlarged view of a portion A of Figure 2;

Figure 4 is an enlarged view of a portion B of Figure 1;

Figure 5 is a cross-sectional view taken along line C-C of Figure 2;

Figure 6 is a force diagram of a roller in an automatic mode in accordance with a preferred embodiment of the present invention;

Figure 7 is a force diagram of a prior art roller in an automatic mode;

Figure 8 is a schematic exploded view of a second embodiment of the present invention;

Figure 9 is a front elevational view of a second embodiment of the present invention;

Figure 10 is an enlarged view of a portion D in Figure 9;

Figure 11 is a schematic view showing the structure of a stent according to a second embodiment of the present invention.

Detailed ways

The above described objects, features, and advantages of the present invention will become more apparent from the detailed description of the embodiments.

The present invention discloses a precision electric screwdriver, such as the preferred embodiment shown in Figures 1-5, including a screwdriver bit and housing 1. The screwdriver bit is located at a distal end of the housing 1. In the present invention, the "distal end" and "proximal end" are definitions for the user. The end farther from the user is the "distal end", and the end closer to the user is the "near end". In this embodiment, the housing 1 is a cylindrical structure having a receiving space formed by the first housing 101 and the second housing 102 fixed together by the locking mechanism 103, which is simple and convenient, and has higher reliability. . Of course, further ultrasonic welding, or other means of attachment that can be conceived by those skilled in the art, are possible.

The housing 1 of the housing 1 is provided with a motor 2, a battery 7 and a circuit board 8 provided with a switch. The housing is provided with a switch button 9 for controlling the switch, and the circuit board 8 is provided by the switch button. 9 Start and drive the motor 7 forward or reverse. An anti-slip sleeve 10 is optionally sleeved on the outside of the housing for ergonomic design.

The screwdriver bit is located in front of the casing 1, and a composite mechanism for realizing manual and automatic mode switching is disposed between the screwdriver bit and the motor 2. Specifically, the composite mechanism includes:

The bearing housing 3, including the stepped inner cavity, is fixed to the housing 1 by a shoulder 31 as shown in FIG. 3;

An output shaft 4 is inserted through the inner cavity of the bearing housing 3 and has a distal end 41 extending from a distal end of the bearing housing 3, and a distal end 41 of the output shaft 4 has a receiving portion for receiving the screwdriver bit The inner end of the output shaft 4 is a step having a diameter larger than the distal end 41 thereof. The step is matched with the stepped inner cavity of the bearing housing 3 to prevent the output shaft 4 from being detached from the housing 1. Fall out axially;

And a rotating frame 5 and a plurality of rollers 50 disposed between the bearing housing 3 and the output shaft 4.

Specifically, the rotating frame 5 includes a backing plate 52 and a plurality of extending arms 51 extending vertically, and the backing plate 52 is provided with a linkage shaft hole that is opposite to the crankshaft of the motor 2, and the motor 2 After the crankshaft is inserted into the linkage shaft hole, the rotating frame 5 can be driven to rotate together.

The automatic and manual mode switching of the present invention is similar to the prior art, in which the rotating frame 5 cooperates with the roller 50 to drive the output shaft 4 to realize an automatic mode of the precision electric screwdriver, the roller 50 will output the output The shaft 4 and the bearing housing 3 are fixed to each other to realize the manual mode of the precision electric screwdriver.

The present invention is characterized in that the outer peripheral surface of the step of the output shaft 4 is formed by a set of curved surfaces which are connected by mutually overlapping outer convex surfaces 43 and concave surfaces 44. An extension arm 51 of the rotating frame extends between the proximal end 42 of the output shaft and the bearing housing 3. The inner diameter of the extension arm 51 is equivalent to the outer diameter of the outer convex surface 43. The roller 50 is axially Between the back plate 52 of the rotating frame and the stepped inner cavity of the bearing housing 3, circumferentially disposed between the inner concave surface 44 and the bearing housing 3, and located between adjacent extending arms 51, The diameter of the roller 50 is larger than the distance between the outer convex surface 43 and the bearing housing 3 and is equivalent to the maximum distance between the inner concave surface 44 and the bearing housing 3.

6 and 7, in the automatic mode, the roller 50 generates an oblique force D1 in the rotational direction of the output shaft 4. Prior Art In the automatic mode, the roller 50 produces a vertical centripetal force D2 to the output shaft 4. Thus, under the same driving force F, the driving force D1=N*Cos b1+F*Sin c1 of the concave surface 44 of the present invention, the driving force D2=N*Cos a1 of the prior art to the output shaft, wherein F : The driving force of the motor to the roller in the automatic mode, N: the reaction force of the bearing seat against the roller, D1: the reaction force of the concave shaft facing the roller in the output shaft, D2: the reaction of the output shaft plane of the prior art to the roller Force, a1: the angle between the bearing seat and the reaction force of the roller and the axis, b: the angle between the reaction force of the output shaft arc facing the roller and the axis (visible in the figure), b1: the bearing seat to the roller The angle of force of the reaction force in the direction of D1 force action, c1: the angle between the driving force of the motor and the vertical direction, L1/L2: the force arm of the roller respectively acting on the output shaft. As can be seen from the drawing, the driving force: D1>D2, driving force arm: L1>L2, the driving torque of the output shaft of the invention: M1=D1*L1, the driving torque of the prior art to the output shaft: M2=D2 *L2, available from above, M1>M2, which increases the torque of the precision electric screwdriver of the present invention, and the driving efficiency is greater than that of the prior art electric screwdriver.

Preferably, the diameter of the roller 50 can be selected to be substantially equal to the maximum distance between the concave surface 44 and the bearing housing 3. Thus, in the manual mode of the present invention, the output shaft does not substantially generate a rotational idle motion, and the user experience is good.

Briefly describe the switching of the manual and automatic modes of the present invention:

The first is the automatic mode operation principle. By controlling the switch button 9 to adjust the forward and reverse rotation of the motor 2 to select to tighten or remove the screw, the control switch button 9 drives the motor 2 to work, the shaft of the motor drives the rotating frame 5 to rotate, and the extension of the support frame 5 The arm 51 drives the roller 50. The roller 50 is engaged with the concave surface 44 of the output shaft and drives the output shaft 4 to rotate. Specifically, the extension arm 51 generates the force in FIG. 6 on the roller 50, and the force passes through the roller. 50 acts on the output shaft 4, and the output shaft 4 finally drives the screwdriver bit to rotate.

Followed by the manual operation principle, when the motor does not work or under the fine operation requirements, directly tighten or remove the screw. When the screwdriver bit rotates the screw, the screwdriver bit produces a reaction force to the output shaft 4 due to the The diameter of the roller 50 is substantially equal to the maximum distance between the concave surface 44 and the bearing housing 3, so when the output shaft 4 rotates, the reaction force generated on the roller 50 is transmitted to the bearing housing 3, and at this time, the output shaft 4, the roller The column 50 and the bearing block 3 are relatively fixed to each other. Since the bearing housing 3 and the housing 1 are fixed, the output shaft 4, the roller 50, the bearing housing 3, the housing 1 and the screwdriver bit are relatively fixed. The batch is consistent with the normal screwdriver usage method, and the user experience is good due to the drastic reduction or even the idle stroke of the output shaft 4.

As shown in FIG. 1 and FIG. 3, an anti-friction pad 91 is further disposed between the bearing housing 3 and the housing 1, and the anti-friction pad 91 is sleeved outside the motor shaft of the motor 2, which can be reduced. The friction between the rotating frame and the housing improves driving efficiency and reduces energy consumption. The two-stage output shaft 4 is more convenient to manufacture, and the overall length of the precision electric screwdriver of the present invention can be shortened, the cost is reduced, and the connection mechanism with the bearing housing 3 is not required.

In the preferred embodiment, the front end of the housing 1 is respectively provided with a front locking sleeve 11 and a rear locking sleeve 12. The rear locking sleeve 12 is disposed between the tail cover 13 and the housing 1 , and the tail cover 13 is screwed to the housing 1 . The front locking sleeve 11 is provided with an LED light tube 14 and a lamp cover 15 . Such front and rear locking mechanisms make the overall reliability of the present invention even higher. Of course, the battery in the present invention may be a dry battery or a rechargeable battery. When a rechargeable battery is used, the housing 1 includes a charging circuit, and the tail cover 13 may be directly welded and integrated with the housing 1.

8 to 11 disclose a second embodiment of the present invention, which, like the prior art, includes a screwdriver bit and a housing 1 in the shape of a circular tube. The housing 1 is provided with a motor 2, the screwdriver A composite output mechanism for manual and automatic mode switching is provided between the head and the motor 2.

In this embodiment, a bracket 300 is fixed in the housing 1 , and the bracket may be made of metal or plastic. The specific structure is as shown in FIG. 11 , and the bracket 300 includes a ring body 3001 and Two struts 3002 symmetrical to each other and extending proximally along the axis of the bracket 300; the outer circumference of the annular body 3001 is provided with a protrusion 3003 for matching the groove 16 in the housing 1 The tight fits are such that the two are radially fixed to each other; the distal end face 3004 of the annular body 3001 cooperates with the projections in the housing 1 to axially fix the two.

The proximal end of the annular body 3001 of the bracket 300 is further provided with an inward convex wall 3005 (shown in FIG. 10), and the supporting piece 3002 is provided with a wedge block 3006, which cooperate with each other to the motor 2 The motor shaft of the motor 2 is directed to the distal end and protrudes from a circular hole formed by the convex wall 3005. The motor 2 has a flat surface 21 that cooperates with the inner surface of the support piece 3002 to radially fix the motor to the bracket 300. Thus, it is very simple to assemble the motor 2, and the motor 2 can be placed between the convex wall 3005 of the bracket 300 and the wedge block 3006. Because of the radially extending structure of the support piece 3002, it has a certain elasticity and is suitable for mounting a motor. Of course, if the shape of the motor changes, the support piece 3002 simply changes its shape to fit the motor.

The composite output mechanism is located at the distal end of the bracket 300. The proximal end of the bracket 300 is provided with a battery 7. The circuit board 8 is also fixed in the bracket 300. The circuit board 8 can be a flexible circuit board or It is an ordinary printed circuit board. The circuit board 8 is electrically connected to the positive and negative poles of the battery 7. The battery 7 may be a common battery such as a dry battery 7 or an integrally charged lithium battery 7, a nickel hydrogen battery 7.

As shown in FIG. 9, the circuit board 8 is fixed to the bracket 300 by screws 22, and one end is located at the proximal end of the motor 2. One end of the circuit board 8 includes positive and negative two-pole contacts of the battery 7, wherein the positive contact contacts the battery 7 through the bayonet 3007 of the proximal end of the support 3002, and the negative contact is located at the The conductive tube 39 at the proximal end of the battery 7 and the conductive spring 38 are electrically connected. The conductive spring 38 is pressed by the tail cap 13.

The other end of the circuit board 8 includes a metal piece conductor 85 extending distally and electrically connected to an LED lamp board 14, the LED light board 14 being snapped by the LED lamp cover 15 The distal end of the housing 1.

The housing 1 is provided with two through holes 17 through which two switch buttons 9 are respectively pressed against the switch contacts 81 of the circuit board 8, and the two ends of the switch button 9 are respectively A barb 94 is provided for preventing the switch button 9 from falling out of the through hole 17. Thus, the switch button 9 is mounted on the housing 1 and the assembly fault tolerance is relatively high.

8 and 10, the composite output mechanism of the present invention includes: a bearing housing 3, an output shaft 4, and a rotating frame 5 and a plurality of rollers disposed between the bearing housing 3 and the output shaft 4 50. The bearing housing 3 includes a stepped inner cavity and is fixed to the bracket 300. The bearing housing 3 is fixed to the bracket 300 by a shoulder 31. The output shaft 4 is inserted into the inner cavity of the bearing housing 3 and the distal end thereof is flush with the distal end of the bearing housing 3, so that the mating length of the two is greatly increased, and the stability of the transmission is improved. The hand-feeling sensation brought by the small prior art achieves the purpose of noise reduction.

The distal end of the output shaft 4 has a hexagon socket for receiving the screwdriver bit and has a magnet 93 inside thereof, and the proximal end of the output shaft 4 is a step having a diameter larger than a distal end thereof, the step and the step The stepped inner cavity of the bearing housing 3 is matched, and the outer peripheral surface of the step is formed by a set of curved surfaces formed by connecting mutually convex outer and inner concave surfaces, and the rotating frame 5 is matched with the roller 50. Driving the output shaft 4 to implement an automatic mode of the screwdriver, the roller 50 fixing the output shaft 4 and the bearing housing 3 to each other to implement a manual mode of the screwdriver.

Specifically, the rotating frame 5 includes a backing plate 14 and a plurality of vertically extending plurality of extending arms 81. The backing plate 14 is provided with a linkage shaft hole that is opposite to the shaft of the motor 2, so that the rotation The frame 5 is coupled to the crankshaft of the motor, and the extension arm 81 extends between the proximal end of the output shaft and the bearing housing 3. The roller 50 is axially disposed on the back plate 14 and the bearing housing 3. The stepped inner chambers are circumferentially disposed between the output shaft 4 and the bearing housing 3 and between the adjacent extension arms 81.

The automatic and manual mode switching of the present invention is similar to the prior art, in which the rotating frame 5 cooperates with the roller 50 to drive the output shaft 4 to realize an automatic mode of the precision electric screwdriver, the roller 50 will output the output The shaft 4 and the bearing housing 3 are fixed to each other to realize the manual mode of the precision electric screwdriver. The outer peripheral surface of the step of the output shaft 4 is formed by a set of curved surfaces which are connected by mutually convex outer and inner concave surfaces. In the automatic mode, the roller 50 generates an oblique force in the rotational direction of the output shaft 4, so that the torque in the automatic mode of the present invention is increased, and the driving efficiency is greater than that of the prior art electric screwdriver. The diameter of the roller 50 can be selected to be substantially equal to the maximum distance between the concave surface and the bearing housing 3, so that in the manual mode of the present invention, the output shaft does not substantially generate a rotating idle stroke, and the user experience is good. The switching of the manual and automatic modes of the present invention is substantially similar to the prior art and will not be described again.

As shown in FIG. 8 and FIG. 10, an anti-friction pad 91 is disposed between the rotating frame 5 and the bracket 300, and the anti-friction pad 91 is sleeved outside the motor shaft of the motor 2. This can reduce the friction between the bracket and the housing, improve driving efficiency and reduce energy consumption. The cylindrical outer shape structure of the output shaft 4 of the present invention is more compact and lower in cost.

A sealing ring 92 is disposed between the bearing housing 3 and the output shaft 4, so that the bearing housing 3 and the proximal end of the output shaft 4 can form a closed space, and lubricating oil can be placed in the space, so that the friction reducing pad can be used. The effect of 91 is greatly enhanced, and the mute effect of the entire screwdriver is greatly increased.

In order to make the silent effect of the screwdriver of the present invention better, it is also possible to wrap a layer of EVA muffler cotton on the outer circumference of the motor 2. In this way, the noise of the motor itself is greatly reduced. This is very helpful for workers who need to work in a quiet environment.

While the present invention has been described in its preferred embodiments, the present invention is not intended to be limited thereto, and the present invention may be modified and improved without departing from the spirit and scope of the invention. The scope of protection is defined by the terms of the claims.

Claims

A precision electric screwdriver, comprising a screwdriver bit and a casing (1), wherein the casing (1) is provided with a motor (2), the screwdriver bit being located in front of the casing (1) A composite mechanism for realizing manual and automatic mode switching is provided between the screwdriver bit and the motor (2), wherein the composite mechanism comprises

a bearing housing (3) including a stepped inner cavity and fixed to the housing (1),

An output shaft (4) is inserted through the inner cavity of the bearing housing (3) and has a distal end (41) extending from a distal end of the bearing housing (3), a distal end of the output shaft (4) (41) having a hexagon socket for receiving the screwdriver bit, the proximal end (42) of the output shaft (4) being a step having a diameter larger than a distal end thereof (41), the step and the bearing seat ( 3) The stepped inner cavity is matched, the outer peripheral surface of the step is formed by a set of curved surfaces, and the set of curved surfaces are formed by connecting mutually convex outer convex surfaces (43) and inner concave surfaces (44).

And a rotating frame (5) and a plurality of rollers (50) disposed between the bearing housing (3) and the output shaft (4), the rotating frame (5) cooperates with the roller (50) to drive the output The shaft (4) implements an automatic mode of the precision electric screwdriver, and the roller (50) fixes the output shaft (4) and the bearing housing (3) to each other to realize a manual mode of the precision electric screwdriver.
A precision electric screwdriver according to claim 1, wherein said rotating frame (5) comprises a backing plate (52) and a plurality of vertically extending plurality of extending arms (51), said backing plate (52) being provided a linkage shaft hole that is opposite to the shaft of the motor (2) such that the rotating frame (5) is coupled to the shaft of the motor, and the extension arm (51) extends into the vicinity of the output shaft Between the end (42) and the bearing housing (3), an inner diameter of the extension arm (51) is equivalent to an outer diameter of the outer convex surface (43), and the roller (50) is axially disposed on the rotating frame Between the back plate (52) and the stepped inner cavity of the bearing housing (3), circumferentially disposed between the concave surface (44) and the bearing housing (3), and located in the adjacent extension arm (51) The diameter of the roller (50) is greater than the distance between the outer convex surface (43) and the bearing housing (3) and is equivalent to the maximum distance between the inner concave surface (44) and the bearing housing (3). .
The precision electric screwdriver according to claim 1, wherein in the automatic mode, the roller (50) generates an oblique force in a rotational direction to the output shaft (4).
The precision electric screwdriver of claim 1 wherein the diameter of the roller (50) is equal to the maximum distance between the inner concave surface (44) and the bearing housing (3).
The precision electric screwdriver of any one of claims 1 to 4, wherein a bracket (300) is fixed in the housing (1), and the motor (2) is fixed inside the bracket (300). The composite output mechanism is located at a distal end of the bracket (300), a proximal end of the bracket (300) is provided with a battery (7), and a circuit board (8) is further fixed in the bracket (300). The circuit board (8) is electrically connected to the positive and negative poles of the battery (7).
A precision electric screwdriver according to claim 5, wherein said bracket (300) comprises a torus (3001) and two branches that are symmetrical to each other and extend proximally along the axis of said bracket (300) a sheet (3002); a protrusion (3003) is disposed on an outer circumference of the torus (3001) for matching a groove (16) in the housing (1), so that the two The radial end faces (3004) of the annular body (3001) cooperate with the projections in the housing (1) to axially fix the two.
The precision electric screwdriver according to claim 6, wherein the proximal end of the annular body (3001) of the bracket (300) is further provided with an inward convex wall (3005), and is disposed at the branch a wedge block (3006) on the sheet (3002) that cooperate to axially fix the motor (2) axially inside the bracket (300), the flat surface (21) of the motor (2) and the The inner surfaces of the segments (3002) cooperate to radially fix the motor to the bracket (300).
The precision electric screwdriver according to claim 7, wherein said circuit board (8) is fixed to said bracket (300) by a screw (22), and the first end thereof is located at said motor (2) a proximal end of the circuit board (8) comprising positive and negative pole contacts of the battery (7), wherein the positive contact contacts the bayonet of the proximal end of the tab (3002) (3007) Directly in contact with the battery (7), the negative contact is electrically connected to a conductive tube (39) and/or a conductive spring (38) located at the proximal end of the battery (7).
The precision electric screwdriver according to claim 8, wherein the housing (1) is provided with two through holes (17) through which two switch buttons (9) respectively pass ( 17) pressing the switch contact (81) of the circuit board (8), the two ends of the switch button (9) are respectively provided with barbs (94) for preventing the switch button (9) from being The through hole (17) falls out.
The precision electric screwdriver according to claim 9, wherein an anti-friction pad (91) is further disposed between the rotating frame (5) and the bracket (300), and the friction reducing pad (91) Nested outside the motor shaft of the motor (2).
A precision electric screwdriver according to claim 10, wherein said bearing housing (3) is fixed to said bracket (300) by a shoulder (31).
A precision electric screwdriver according to any one of claims 1 to 4, wherein said housing (1) is passed through a latching mechanism (103) by a first housing (101) and a second housing (102) A cylindrical structure having a receiving space formed by being fixed together.
A precision electric screwdriver according to claim 12, wherein said bearing housing (3) is fixed to said housing (1) by a shoulder (31).
The precision electric screwdriver according to claim 13, wherein an anti-friction pad (91) is further disposed between the bearing housing (3) and the housing (1), and the friction reducing pad (91) ) is sleeved outside the motor shaft of the motor (2).
The precision electric screwdriver according to claim 14, wherein a battery (7) and a circuit board (8) provided with a switch are disposed in the housing, and the housing is provided with a switch for controlling the switch a switch button (9), and a non-slip sleeve (10) sleeved outside the casing; the two ends of the casing (1) are respectively provided with a front locking sleeve (11) and a rear locking sleeve (12) The rear locking sleeve (12) is disposed between the tail cover (13) and the housing (1), the tail cover (13) is screwed to the housing (1), and the front locking sleeve (11) ) There are LED light pipes (14) and lamp covers (15).
A precision electric screwdriver according to any one of claims 1 to 4, characterized in that a seal ring (92) is provided between the bearing housing (3) and the output shaft (4) for The bearing housing (3) forms a closed space with the proximal end of the output shaft (4).
A precision electric screwdriver according to any one of claims 1 to 4, characterized in that the distal end of the output shaft (4) is flush with the distal end of the bearing block (3).
A precision electric screwdriver according to any one of claims 1 to 4, wherein the distal end of the output shaft (4) has a hexagon socket for receiving the screwdriver bit and has a magnet (93) therein. .