JP3819078B2 - Electric rotary tool with built-in non-reaction clutch mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric rotary tool having a built-in clutch mechanism, and in particular, when a work torque of the electric rotary tool receives a load torque exceeding a certain level, this state is detected and the output shaft of the electric motor is changed to a work axis. Non-reaction clutch configured to prevent sudden repulsion due to the torque transmitted to the driven shaft and the torque adjustment spring, to make the impact vibration in the thrust direction non-reaction and to increase the torque accuracy The present invention relates to an electric rotary tool incorporating a mechanism.
[0002]
[Prior art]
Conventionally, in an electric rotary tool such as an electric screwdriver, when tightening of a screw or the like is completed, a driver bit coupled via the driven shaft of the output shaft of the electric motor is subjected to a load torque above a certain level. There is known a clutch mechanism configured to detect the rotation and block transmission of rotational output to the driven shaft.
[0003]
As a means for detecting such load torque, the rotational driving force from the output shaft of the electric motor is transmitted to the driven shaft through a reduction mechanism comprising a planetary gear mechanism, and a load torque of a certain level or more is applied to the driven shaft. In such a case, the internal gear that meshes with the planetary gear is known to be configured such that the clutch engagement is disengaged and the inside of the casing rotates to cut off the transmission of the rotational force from the output shaft to the driven shaft. (Japanese Patent Laid-Open No. 60-16370).
[0004]
However, in the conventional clutch mechanism, in order to lock the internal gear to the casing, a roller is embedded in a part of the internal gear, and a steel ball is elastically engaged with this roller in the thrust direction of the driven shaft. When a load torque of a certain level or more is applied, the roller gets over the steel ball and the transmission of the rotational force to the driven shaft is cut off. Therefore, when the roller gets over the steel ball, the spring release compression force acts on the member that contacts the steel ball and supports it by the elastic force of the torque adjusting spring. It collides violently with the outer surface of the internal gear via. The impact caused by this violent collision is transmitted as vibrations in the lateral direction of the driven shaft, that is, in the lateral direction, or in the vertical direction, that is, in the longitudinal direction. Was given as a vibration.
[0005]
Even in the case of a clutch mechanism using a method in which the internal gear is locked to the casing by the elastic clutch engagement of the steel ball, the ordinary electric rotary tool is more than the case of tightening the screws and the like. When the tightening screw is loosened, a high torque torque is required.
[0006]
Therefore, if a high torque torque is transmitted to the driven shaft during reverse rotation without changing the elasticity of the torque adjusting spring that pushes up the steel ball, it will be properly locked during reverse rotation of the internal gear. In addition, for example, it is necessary to cause the reverse end portion of the clutch engagement protrusion to protrude at a steep inclination angle or to further protrude the reverse end portion together therewith. For this reason, at the time of screw tightening, the steel ball riding on the protruding portion jumps over the protruding portion, jumps over the opposite end of the protruding portion, and violently collides with the outer surface of the internal gear, thereby vibrating the electric rotary tool. As a result, an unpleasant impact sound is produced.
[0007]
As described above, in the clutch mechanism using the steel ball, immediately after the tightening of the screw or the like is completed, the steel ball moves over the clutch cam surface provided with the roller by the elasticity of the torque adjusting spring. A phenomenon of bouncing on the cam surface occurs. For example, as shown in FIG. 6, the bounce phenomenon of the steel ball is transmitted as a vibration in the transverse direction with respect to the driven shaft, and generates a force FL in a loosening direction that is opposite to the tightening of a screw or the like. Problems arise.
[0008]
During the clutch operation of the clutch mechanism, the steel ball bounces off the cam surface and then violently collides with the outer surface of the internal gear, whereby the driven shaft transmits the longitudinal impact vibration with the generation of the impact sound. Is done. The vibration and impact sound generated in this way not only makes the operator operating the electric rotary tool uncomfortable, but also for products that are installed with screws etc., especially semiconductor parts and precision parts. In the screw tightening operation for assembling the above, such vibrations and shocks cause damage to these parts, resulting in the occurrence of defective products that cause malfunctions. In particular, with regard to impact, a causal relationship has been recognized in which vibration causes a product to go wrong.
[0009]
In addition, the vibration generated by the operation of the clutch mechanism shortens the durability of the electric rotary tool, and even if the operator who operates it strongly holds the electric rotary tool, it causes blurring when screw tightening is completed, The screw that had been tightened was to be loosened. That is, there is a problem that the torque value at the time of screw tightening is not fixed and becomes unstable, and the actual screw tightening state cannot be confirmed.
[0010]
Furthermore, the horizontal and vertical impact vibrations transmitted to the driven shaft during the clutch operation may cause tendonitis in the worker who grasps the electric rotary tool for a long time. It also had an adverse effect.
[0011]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to solve the above-mentioned problem, when the steel ball acting on the clutch cam surface gets over the engaging protrusion of the cam surface when the clutch operation is performed. Is set so that it does not abruptly collide with the outer surface of the internal gear, but is fixed to the inner peripheral surface of the gear case via a one-way clutch. Reduce frictional resistance during internal gear rotation and effectively achieve power transmission to the work shaft during reverse rotation to prevent impact vibration and improve torque accuracy during screw tightening It is an object of the present invention to provide an electric rotary tool having a built-in reactionless clutch mechanism.
[0012]
In this case, since there is no reaction at the time of clutch operation, it is difficult to instantly check the clutch operation state. Therefore, an electric circuit linked to the clutch mechanism is provided for the convenience of the operator. It is an object of the present invention to provide an electric rotary tool having a built-in non-reaction clutch mechanism provided with means for providing external display such as light emission during clutch operation.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, an electric rotary tool incorporating a non-reaction clutch mechanism according to the present invention has a driven shaft as a work shaft coupled to an output shaft of an electric motor via a reduction mechanism comprising a planetary gear mechanism. when more than a predetermined value of the load torque is applied against the driven shaft, an electric rotary tool having a built-in configuration the clutch mechanism so as to perform a clutch operation of blocking engagement with the output shaft and the driven shaft, the planetary It is fixedly placed in the cylindrical casing of the electric rotary tool via a one-way clutch on the outer periphery of the internal gear that is arranged so as to mesh with the gear mechanism, and is held by a part of this internal gear via a torque adjustment spring. A clutch cam surface is formed with a protrusion that performs a clutch operation that elastically abuts and locks the steel ball to be cut off to disengage the output shaft from the driven shaft. When the load torque exceeds the preset torque value and the steel ball gets over the protrusion on the clutch cam surface, the clutch cam surface is formed and the internal gear is driven so that the steel ball is slowly restored. A protrusion formed on the clutch cam surface of the internal gear in an electric rotary tool that is set so as to be rotatable only in the reverse direction of the shaft and further includes a non-reaction clutch mechanism provided with means for externally displaying the clutch operation. Is characterized in that the portion that abuts when the steel ball crosses the protrusion is made of an elastic buffer member .
[0014]
In this case, the non-reaction clutch mechanism is connected to the output shaft of the electric motor via a planetary gear mechanism and a one-way clutch on the inner periphery of a gear case fixed in a cylindrical casing surrounding the planetary gear mechanism. An internal gear that meshes with the planetary gear is housed and disposed, and a steel ball is fitted to the gear case at the axial contact surface between the internal gear and the gear case, and is opposed to the internal gear to the internal gear. A clutch cam surface having a protrusion engaging with the steel ball is formed, and the steel ball is elastically held by a sleeve having a resilient action in the thrust direction of the driven shaft via a torque adjusting spring, and screwed. When the load torque on the driven shaft is below the specified value during operation, the internal gear is locked to the gear case and the load torque is The internal gear rotates in the direction opposite to the rotation direction of the driven shaft when the shaft exceeds the upper limit, and the steel ball gets over the protrusion on the clutch cam surface and interrupts the engagement between the output shaft and the driven shaft. It can be configured to perform a clutch operation.
[0015]
As means for externally displaying the clutch operation, there is provided switch means for detecting the displacement of the clutch cam surface due to the clutch operation to open and close the electric circuit, and charging the electric circuit provided with the switch means with a predetermined amount of electricity. It is characterized by connecting a capacitor for discharging and a light emitting diode.
[0016]
Further, the protrusion formed on the clutch cam surface of the internal gear has an inclined surface that protrudes at a required inclination angle facing the steel ball, a flat surface that continues to the inclined surface, and a gentle inclination angle thereafter. It is possible to set the inclined surface that terminates at the slow inclination angle over a range that is approximately ½ of the entire circumference of the clutch cam surface.
[0019]
The one-way clutch that surrounds and holds the internal gear includes a ring member in which a plurality of rollers are fitted and arranged on the inner peripheral surface at a predetermined interval in the circumferential direction, and in the fitting groove of the roller, Each of the rollers can be constructed by inserting wedge pieces so as to allow rolling in only one direction.
[0020]
【Example】
Next, an embodiment of the electric rotary tool incorporating the non-reaction clutch mechanism according to the present invention will be described in detail with reference to the accompanying drawings.
[0021]
FIG. 1 is a schematic cross-sectional view of an essential part showing an embodiment of an electric rotary tool according to the present invention. That is, in FIG. 1, reference numeral 10 indicates a gripping portion of an electric rotary tool having an electric motor (not shown) built therein, and a non-reaction clutch mechanism 12 is provided at the tip of the gripping portion 10.
[0022]
However, the non-reaction clutch mechanism 12 fixes the pinion gear 16 to the tip of the output shaft 14 of the electric motor, and meshes and connects the speed reduction mechanism including the planetary gear mechanism 18 via the pinion gear 16. An internal gear 22 that meshes with the planetary gear 20 is disposed on the outer periphery of the planetary gear mechanism 18.
[0023]
The internal gear 22 is press-fitted and fixed to an inner peripheral portion of a gear case 26 fixedly disposed in the cylindrical casing 24 via a one-way clutch 28 so as to be rotatable in a predetermined direction. In this case, when the one-way clutch 28 rotates the output shaft 14 of the electric motor in the forward direction, the planetary gear mechanism 18 rotates in the same direction as the output shaft 14. At this time, the internal gear 22 is connected to the planetary gear mechanism 18. Is coupled to the one-way clutch 28 so as to be rotatable in the opposite direction.
[0024]
However, as shown in FIG. 2, for example, the one-way clutch 28 includes a ring member 32 in which a plurality of rollers 30 having a small frictional contact resistance are fitted and arranged on the inner peripheral surface at a predetermined interval in the circumferential direction. A wedge piece 36 is inserted into the fitting groove 34 of the roller 30 so as to allow the roller 30 to roll only in one direction. Therefore, by inserting and fixing the internal gear 22 so as to be in pressure contact with the surface of the roller 30, the internal gear 22 is prevented from rolling to the side where the wedge piece 36 of the roller 30 is inserted. Therefore, the rotation is prevented, and the rotation is smoothly performed in the opposite direction.
[0025]
Further, the closed bottom surface portion 22a of the internal gear 22 has a central portion passing through a driven shaft 38 that is coaxially connected to the output shaft 14 via the planetary gear mechanism 18, and is outside the closed bottom surface portion 22a. A clutch cam surface provided with a protrusion 40 for performing a clutch operation is formed on the bottom surface (see FIG. 3A).
[0026]
Therefore, as one embodiment of the present invention, the protrusion 40 on the clutch cam surface provided on the closed bottom surface portion 22a of the internal gear 22 is, for example, a driven shaft 38 as shown in FIGS. During forward rotation, the steel ball 42 protrudes at the required inclination angle (inclined surface 23a) in the required angle range in the same direction as the direction in which the steel ball 42 abuts, that is, the normal rotation direction of the driven shaft 38 (indicated by arrow R). At the same time, a required flat portion (flat surface 23b) is formed continuously, and then, it is formed so as to end at a gentle inclination angle (inclined surface 23c). The protrusion 40 has, for example, a portion 23a protruding at a required inclination angle substantially the same as that of a conventional roller, and a portion 23c having a gentle inclination angle is formed on the closed bottom surface portion 22a of the internal gear 22. It is configured so as to gradually decrease over approximately half of the entire circumference.
[0027]
In the embodiment shown in FIG. 1, a driver bit for tightening a screw or bolt is detachably connected to the tip of the driven shaft 38.
[0028]
In addition, a hole 44 for fitting a steel ball 42 is provided on the bottom surface of the gear case 26 at a position corresponding to the protrusion 40 provided on the internal gear 22. Thereby, the steel ball 42 is elastically engaged with the protrusion 40 provided on the outer bottom portion of the internal gear 22 by the sleeve 48 pushed upward by the torque adjusting spring 46 formed of a coil spring.
[0029]
In the non-reaction clutch mechanism 12 configured as described above, when the screw tightening operation is performed, the steel ball 42 and the protrusion 40 are elastically engaged in the thrust direction of the driven shaft 38, and the internal gear 22 is engaged with the gear case 26. Since the rotation driving force transmitted through the output shaft 14 is transmitted to the planetary gear 20 through the pinion gear 16 and revolves while rotating, the planetary gear mechanism is engaged. The driven shaft 38 coupled to the rotary shaft 18 is driven to rotate, and a screw or bolt is tightened.
[0030]
When the tightening torque (load torque) in a tightening operation of a screw or the like reaches a predetermined torque value set in advance, the rotation of the driven shaft 38 stops, and the rotational force transmitted from the output shaft 14 of the electric motor is It is transmitted to the internal gear 22 through the pinion gear 16 through the rotation of the planetary gear 20 of the planetary gear mechanism 18. When the load torque exceeds a predetermined value, the steel ball 42 that is elastically engaged with the protrusion 40 provided on the outer bottom portion of the closed bottom surface portion 22a of the internal gear 22 is pushed downward, and the protrusion The part 40 gets over the steel ball 42 and the engagement between the protrusion 40 and the steel ball 42 is released. That is, the clutch operation is achieved. As a result, the internal gear 22 rotates in the gear case 26 together with the planetary gear 20, and transmission of the rotational driving force from the output shaft 14 to the driven shaft 38 is cut off.
[0031]
In this case, that is, when the engagement between the protrusion 40 and the steel ball 42 is released, the sleeve 48 is pushed downward against the elasticity of the torque adjusting spring 46. Therefore, as shown in FIG. 1, a limit switch 50 is arranged close to the sleeve 48, and the limit switch 50 is operated in accordance with the clutch operation to energize a required electric circuit. Can do.
[0032]
Therefore, the electric circuit operated by the limit switch 50 can be configured, for example, as shown in FIG. That is, in FIG. 4, reference numeral SW1 is a power switch of the electric rotary tool, SW2 is a forward / reverse switching switch, ZD is a constant voltage diode, M is an electric motor, and these are limit switches 50 having normally open contacts. And connected to be cut off. Further, the diode D, the capacitor C, the resistor R, and the light emitting diode LED are connected and arranged as shown in the figure via the limit switch 50 to constitute an external display means 52 for externally displaying the clutch operation. In this case, the light emitting diode LED may be installed by selecting a location that is easily visible to the electric rotary tool. Various signal generating elements can be used instead of the light emitting diode LED.
[0033]
Thus, when the reactionless clutch mechanism 12 according to the present invention operates, the protrusion 40 of the clutch cam surface formed on the outer bottom portion of the internal gear 22 has a positive shaft 38 as shown in FIG. When the steel ball 42 is pushed down to return to its original position, the steel ball 42 protrudes at the required inclination angle in the same direction as the rolling direction and then terminates at a gentle inclination angle. There is no sudden collision with the outer bottom of the internal gear 22. Accordingly, there is no impact caused by the steel ball 42 colliding with the internal gear 22, so that no impact vibration or impact sound is generated on the electric rotary tool. In this case, the clutch operating state can be immediately confirmed by the external display means 52.
[0034]
In the present invention, in the non-reaction clutch mechanism 12, the internal gear 22 is fixed to the inner peripheral portion of the gear case 26 via the one-way clutch 28 having the above-described configuration, so that the driven shaft 38 is rotated forward. In the meshing connection with the planetary gear 20 when performing the clutch operation, the rotational drive force of the output shaft 14 accompanying the rotation stop of the driven shaft 38 can be rotated so as to be smoothly absorbed. As a result, the accuracy of the screw tightening torque can be significantly increased.
[0035]
On the other hand, during the reverse rotation of the output shaft 14, the rotation of the internal gear 22 in the revolving direction of the planetary gear 20 is immediately blocked by the one-way clutch 28, and all the rotational driving force is efficiently transmitted to the driven shaft 38. Is done. As a result, a high torque torque can be transmitted to the driven shaft 38 when the screw is removed.
[0036]
Thus, in the electric rotary tool incorporating the non-reaction clutch mechanism 12 of the present invention, when the load torque on the driven shaft 38 exceeds the preset torque setting value and the clutch operation is performed, the protrusion 40 is When the steel ball 42 is overcome, the protrusion 40 and the steel ball 42 are disengaged, and the pushed-down steel ball 42 does not suddenly collide with the outer bottom of the internal gear 22 when returning to its original position. It is important to set so that the return operation is performed slowly. Therefore, in this case, improving the shape of the protrusion as in the embodiment shown in FIG. 3 is merely an example. That is, for example, a protrusion formed on the clutch cam surface of the internal gear so that the pressed steel ball 42 comes into contact with the outer bottom portion of the internal gear 22 so as not to suddenly collide when returning to the original position. In the part, the part that abuts when the steel ball crosses the protruding part is configured with an elastic buffer member, or the torque adjusting spring is configured so as to be gradually elastically restored upon compression release, Means such as partially changing the material of the portion on which the steel ball acts can be employed.
[0037]
The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the spirit of the present invention.
[0038]
【The invention's effect】
As is apparent from the above-described embodiments, the electric rotary tool incorporating the non-reaction clutch mechanism according to the present invention couples the driven shaft as the work shaft to the output shaft of the electric motor via the speed reduction mechanism including the planetary gear mechanism. and, when the load torque of a predetermined value or more with respect to the driven shaft is applied, met electric rotating tool with a built-in configuration the clutch mechanism so as to perform a clutch operation of blocking engagement with the output shaft and the driven shaft Then, it is fixedly arranged in the cylindrical casing of the electric rotary tool on the outer periphery of the internal gear arranged so as to mesh with the planetary gear mechanism through a one-way clutch, and a torque adjusting spring is provided in a part of the internal gear. A clutch cam surface having a protrusion that performs a clutch operation to elastically abut and lock the steel ball held through the output shaft and disconnect the engagement between the output shaft and the driven shaft. When the load torque exceeds the preset torque value and the steel ball gets over the protrusion on the clutch cam surface, the clutch cam surface is formed and the internal gear is set so that the steel ball is slowly restored. Is formed on the clutch cam surface of the internal gear in an electric rotary tool incorporating a non-reaction clutch mechanism provided with means for externally displaying the clutch operation. The projecting portion is made of an elastic buffer member at the part that abuts when the steel ball crosses the projecting portion, so that the steel ball acting on the clutch cam surface when the clutch operation is performed in the screw tightening operation. When overcoming the engagement protrusion on the cam surface, the steel ball can be brought into contact slowly with the outer surface of the internal gear to prevent impact vibration. At the same time, the clutch operating state can be easily confirmed, and the internal gear is fixed to the inner peripheral surface of the gear case via a one-way clutch, so that friction during rotation of the internal gear during clutch operation is achieved. The resistance can be reduced, the torque accuracy of the tightening torque can be improved, and the power transmission to the work shaft during the reverse rotation drive can be effectively achieved.
[0039]
That is, as a non-reaction clutch mechanism, for example, a driven shaft is coupled to an output shaft of an electric motor via a planetary gear mechanism, and a one-way clutch is provided on an inner peripheral portion of a gear case fixed in a cylindrical casing surrounding the planetary gear mechanism. An internal gear that meshes with the planetary gear is housed and disposed, and a steel ball is fitted to the gear case at an axial contact surface between the internal gear and the gear case, and the internal gear is opposed to the internal gear. A clutch cam surface having a protrusion engaging with a steel ball is formed, and the steel ball is elastically held by a sleeve having a resilient action in the thrust direction of the driven shaft via a torque adjusting spring, and screw tightening operation is performed. If the load torque on the driven shaft is less than the predetermined value, the internal gear is locked to the gear case and the load torque is When the constant torque is exceeded, the internal gear rotates in the direction opposite to the direction of rotation of the driven shaft, and the steel ball gets over the protrusion on the clutch cam surface and disconnects the output shaft from the driven shaft. As shown in FIG. 5, it was confirmed that the lateral vibration generated during the clutch operation in the conventional electric rotary tool can be almost completely removed by the configuration that performs the clutch operation.
[0040]
Similarly, according to the electric rotary tool incorporating the non-reaction clutch mechanism of the present invention, it is possible to almost eliminate vertical vibrations, thereby reliably preventing the generation of impact vibrations and impact sounds. Can do. Incidentally, as a result of measuring the vibration in the longitudinal direction, it was confirmed that according to the present invention, it can be reduced to about 1/30 compared with the conventional apparatus.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of an essential part showing an embodiment of an electric rotary tool incorporating a non-reaction clutch mechanism according to the present invention.
2 is an enlarged cross-sectional view of a principal part taken along line II-II of the reactionless clutch mechanism shown in FIG.
FIG. 3 is an explanatory view of a main part showing an example of a shape configuration of a protrusion provided on an internal gear having a clutch function in the non-reaction clutch mechanism shown in FIG. 1, wherein (a) is a bottom view; (B) is a schematic side view seen from the B direction of (a), (c) is a schematic side view seen from the C direction of (a), and (d) is a schematic side view seen from the D direction of (a). FIG.
FIG. 4 is an electric circuit diagram showing an embodiment of external display means for externally displaying the clutch operation in the electric rotary tool incorporating the non-reaction clutch mechanism according to the present invention.
FIG. 5 is a left-right shock vibration waveform diagram generated on the driven shaft when the clutch of the electric rotary tool incorporating the non-reaction clutch mechanism according to the present invention is operated.
FIG. 6 is a left and right impact vibration waveform diagram generated on a driven shaft when a clutch of an electric rotary tool provided with a conventional clutch mechanism is operated.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Holding part 12 Non-reaction clutch mechanism 14 Output shaft 16 Pinion gear 18 Planetary gear mechanism 20 Planetary gear 22 Internal gear 22a Closed bottom part 23a Inclined surface 23b of required inclination angle Flat surface 23c Inclined surface 24 of gentle inclination angle Cylindrical shape Casing 26 Gear case 28 One-way clutch 30 Roller 32 Ring member 34 Fitting groove 36 Wedge piece 38 Drive shaft 40 Protruding portion 42 Steel ball 44 Hole portion 46 Torque adjusting spring 48 Sleeve 50 Limit switch 52 External display means

Claims (5)

When a driven shaft as a work shaft is coupled to the output shaft of the electric motor via a speed reduction mechanism including a planetary gear mechanism, and when a load torque of a predetermined value or more is applied to the driven shaft, the output shaft and the driven shaft the electric rotating tool with a built-in clutch mechanism configured to perform a clutch operation to cut off the engagement with the electric rotating through a one-way clutch to the outer periphery of the internal gear that surrounds arranged to the planetary gear mechanism meshes A steel ball that is fixedly placed in the cylindrical casing of the tool and elastically abuts and locks a steel ball held through a torque adjustment spring on a part of this internal gear to engage the output shaft and the driven shaft. A clutch cam surface having a protrusion for performing a clutch operation is formed, and when the driven shaft rotates forward, the load torque exceeds a preset torque value, and the steel ball rides on the protrusion on the clutch cam surface. When exceeding, the means for forming a clutch cam surface and set pivotably internal gear only in the reverse direction of the driven shaft, to further external display the clutch operation to perform slow return movement of the steel balls In the electric rotary tool with built-in non-reaction clutch mechanism,
Electric rotation with built-in non-reaction clutch mechanism, characterized in that the protrusion formed on the clutch cam surface of the internal gear is made of an elastic buffer member at the part where the steel ball abuts when it exceeds the protrusion tool.   The non-reaction clutch mechanism has a driven shaft coupled to an output shaft of an electric motor via a planetary gear mechanism, and a planetary gear connected to the inner periphery of a gear case fixed in a cylindrical casing surrounding the planetary gear mechanism via a one-way clutch. An internal gear that meshes with the gear is housed and disposed, and a steel ball is fitted to the gear case on the contact surface in the axial direction of the internal gear and the gear case, and the steel ball is opposed to the internal gear and opposed to the steel ball. A clutch cam surface having a protrusion for engaging the clutch is formed, and the steel ball is elastically held by a sleeve having a resilient action in the thrust direction of the driven shaft via a torque adjusting spring, and is driven during screw tightening operation. When the load torque on the shaft is below the specified value, when the internal gear is locked to the gear case and the load torque exceeds the set torque The internal gear rotates in the direction opposite to the rotation direction of the driven shaft so that the steel ball moves over the protrusion on the clutch cam surface and performs a clutch operation to cut off the engagement between the output shaft and the driven shaft. The electric rotary tool which built the non-reaction clutch mechanism of Claim 1 comprised.   The means for externally displaying the clutch operation is provided with switch means for detecting the displacement of the clutch cam surface due to the clutch operation to open / close the electric circuit, and charging / discharging the electric circuit provided with the switch means with a predetermined amount of electricity. The electric rotary tool incorporating the non-reaction clutch mechanism according to claim 1, wherein the electric rotary tool is constructed by connecting a capacitor and a light emitting diode.   The protrusion formed on the clutch cam surface of the internal gear is opposed to the steel ball and protrudes at a required inclination angle, a flat surface continuous to the inclined surface, and then ends at a gentle inclination angle. The non-reaction clutch mechanism according to claim 1, wherein the non-reaction clutch mechanism comprises an inclined surface, and the inclined surface that terminates at a slow inclination angle is set over a range that is approximately ½ of the entire circumference of the clutch cam surface. Built-in electric rotary tool.   The one-way clutch that surrounds and holds the internal gear is composed of a ring member in which a plurality of rollers are fitted and arranged on the inner circumferential surface at a predetermined interval in the circumferential direction, and the rollers are respectively placed in the fitting grooves of the rollers. The electric rotary tool incorporating the non-reaction clutch mechanism according to claim 1, wherein a wedge piece is inserted so as to allow rolling only in one direction.

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