JP2003165065A - Tightening tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique capable of judging accurately finish of tightening a screw and the like, even when hammering or the like is caused by looseness between a socket and a bolt. <P>SOLUTION: In this tightening tool of the present invention, rotation of a motor is transmitted to a load shaft 8 via an impact force generating mechanism 12, and the screw is tightened by rotation of the load shaft 8. A detector 10 is provided in the load shaft 8 to detect a rotational direction and a rotation angle change of the shaft 8. Stop of rotation of the screw or seating of the screw is judged based on the rotational direction and the rotation angle change of the shaft 8 detected by the detector 10, and the motor is stopped after a prescribed time counted form the stop of the rotation of the screw or the seating of the screw. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a tightening tool such as an impact wrench, an impact driver, and a torque wrench, in which rotation of a motor is transmitted to a load shaft through an impact force generating mechanism.

[0002]

2. Description of the Related Art With tightening tools such as impact wrenches,
Motor rotation impact force generation mechanism (for example, mechanical impact force generation mechanism that hits anvil (load shaft) with a hammer, oil unit that generates impact force with hydraulic pressure, etc.)
By transmitting to the load shaft via, the load shaft is rotated and screws such as bolts and nuts are tightened. Although this type of tightening tool can obtain a high tightening torque, it may cause damage to the screw due to over-tightening, or insufficient tightening torque due to early stopping of screw tightening due to fear of screw damage. Occurs. Therefore, a technique for making the screw tightening torque constant has been conventionally developed. In the related art, a rotation detection device that detects the rotation speed of the load shaft and a control device that controls the drive of the motor based on the rotation speed detected by the rotation detection device are provided. The control device stops driving the motor when the number of rotations of the load shaft detected by the rotation detection device becomes equal to or lower than a predetermined value. Therefore, according to this technique, while the rotation speed of the load shaft exceeds the predetermined value,
That is, while the load shaft is rotating, the motor is driven and the screws are tightened. On the contrary, when the rotation speed of the load shaft becomes equal to or lower than the predetermined value, it is determined that the tightening of the screws is completed and the rotation of the load shaft is stopped.

[0003]

[Patent Document 1] Japanese Patent Application Laid-Open No. 8-290368

[Patent Document 2] Japanese Patent Laid-Open No. 6-99362

[Patent Document 3] Japanese Patent Laid-Open No. 2001-277146

[0004]

However, in the above-described conventional technique, it is possible to accurately determine the completion of tightening of screws depending on the engagement state of the screw and the socket and the state of the screw and the member to be fastened. There were times when I couldn't. For example, there may be rattling between the socket (attached to the tip of the load shaft or the like) and the screw head that engages with the socket. In this case, when the impact force of the load shaft is transmitted to the screw, the load shaft repeats forward rotation (rotation in the screw tightening direction) and reverse rotation (rotation in the screw loosening direction) due to its reaction (hammering action). Tighten. For this reason, even if the tightening of the screws is completed, the socket (that is, the load shaft) repeats forward and reverse rotations due to hammering, and the rotation speed of the load shaft may not drop below a predetermined value. Therefore, it is impossible to determine the completion of screw tightening with the conventional technique. Further, for example, when there are burrs or the like on the screws and / or the member to be tightened, a high load may act on the load shaft at the timing before the completion of the tightening of the screws due to the burrs. When a high load acts on the load shaft, the number of rotations of the load shaft becomes a predetermined value or less, and therefore, in the conventional technique, it is determined that the tightening of screws is completed before the screw is completely tightened. The present invention has been made in view of the above circumstances, and an object thereof is to provide a technique capable of accurately determining completion of tightening of screws.

[0005]

In order to solve the above-mentioned problems, the tightening tool according to the first invention of the present application,
In a tightening tool that tightens screws by rotating the load shaft by transmitting the rotation of the motor to the load shaft through an impact force generation mechanism, a detection device that detects changes in the rotation direction and rotation angle of the load shaft is provided. Prepare With the above tightening tool, not only the change in the rotation angle of the load shaft but also the rotation direction is detected. Therefore, even if the load shaft repeats normal rotation and reverse rotation by hammering or the like, it is possible to distinguish whether the detected change in the rotation angle is the rotation of the load shaft in the normal rotation direction or the reverse rotation direction. Therefore, it is possible to accurately determine the completion of tightening of the screws and the seating of the screws.

The detection device has a first detection sensor for detecting a change in the rotation angle of the load shaft and a second detection sensor for detecting a change in the rotation angle of the load shaft. The detection signal output and the detection signal output from the second detection sensor are deviated by a first phase angle when the load axis rotates in the forward direction and by a second phase angle when the load axis rotates in the reverse direction. It is preferable that they are deviated. According to such a configuration, due to the phase shift between the detection signal output from the first detection sensor and the detection signal output from the second detection sensor,
It is possible to detect whether the load shaft is rotating normally or reversely.
Further, the change in the rotation angle of the load shaft can be detected by the detection signal of the first detection sensor and / or the detection signal of the second detection sensor. Here, the above "detection sensor"
As the above, various conventionally known ones can be used. For example, a photo interrupter (which optically detects a change in the rotation angle of the load shaft) arranged so as to sandwich the slit of the shield plate attached to the load shaft, or a change in the magnetic field due to the magnet attached to the load shaft is detected. A magnetic sensor or the like arranged as described above can be used. When the magnetic sensor is used, the influence of mechanical oil, dust, etc. is eliminated, so that the change in the rotation angle of the load shaft can be accurately detected.

When the first detection sensor and the second detection sensor are provided as described above, a bearing device for rotatably supporting the load shaft is further provided, and the bearing device is fixed to the load shaft. And an outer cylinder portion that rotatably supports the inner cylinder portion, wherein the first detection sensor and the second detection sensor are arranged in the outer cylinder portion. preferable. In such a configuration, the load shaft is fixed to the inner cylinder of the bearing device, and the first detection sensor and the second detection sensor are arranged on the outer cylinder supporting the inner cylinder. Therefore, the clearance between the inner cylinder portion (that is, the load shaft) and the outer cylinder portion (that is, the first detection sensor and the second detection sensor) is maintained substantially constant, and the detection accuracy of the rotation angle detection sensor is high. Can be improved. The bearing device and the detection device may be integrated as a sub-assembly by previously incorporating the first detection sensor and the second detection sensor in the outer cylinder part. In such a case, it is not necessary to adjust the arrangement positions of the two detection sensors in the final assembly process of the tightening tool, and the final assembly process can be simplified. In the above case, when magnetic sensors are used as the first detection sensor and the second detection sensor, a plurality of magnets are arranged at regular intervals on the inner cylinder wall surface facing the magnetic sensors, It is preferable that the magnetic poles of the plurality of magnets on the side facing the magnetic sensor are arranged so that the S poles and the N poles alternate.

The method of determining the motor stop timing using the above-described detection device includes a method of setting the motor stop timing when the rotation of the load shaft is stopped, and a motor stop timing based on when the screws are seated. A method of determining, etc. can be used. When the above method is used, in the tightening tool including any of the above-described detection devices, it is determined that the rotation of the load shaft is stopped from the rotation direction and the rotation angle change of the load shaft detected by the detection device. It is preferable to further include a control device that controls to stop the rotation of the motor after a predetermined time from the timing. With this configuration, the screws are further tightened after they are seated, and the motor is automatically stopped when the screws are no longer rotated in the screw tightening direction. For this reason, the motor is driven as long as the screw rotates, and when the screws stop rotating, the motor automatically stops. Therefore, overtightening of the screws is prevented. Here, the determination of the rotation stop of the screws is made by, for example, the amount of change in the rotation angle of the load shaft in the forward rotation direction and the amount of change in the rotation angle in the reverse rotation direction are balanced, and the load shaft rotates further in the forward rotation direction. It can be judged that the rotation of the screws has stopped when the rotation is stopped. Therefore, the control device rotates the load shaft alternately in the screw tightening direction and the screw loosening direction, and when the rotation angle change in the screw tightening direction does not exceed the rotation angle change in the screw loosening direction continues for a predetermined time. It is preferable to stop the rotation of the motor. A mechanical impact force generation mechanism, an oil unit, or the like can be used as the impact force generation mechanism of the tightening tool that adopts this method, but an impact force generation mechanism that uses hydraulic pressure of the oil unit or the like should be used. Is preferred. Since the impact force generating mechanism using hydraulic pressure can adjust the magnitude of the impact force by adjusting the hydraulic pressure, the tightening torque can be accurately controlled by operating until the screws do not rotate.

When the above method is used, it is necessary to determine the timing at which the screws are seated. To determine the seating of screws, (a) the time required for the load shaft to rotate in the screw tightening direction by the minimum resolution of the detection device, (b) the time interval of the detection signal output from one of the detection sensors, The seating of the screws can be determined based on the difference between the time intervals, the change over time of the time intervals, and the like. In other words, the physical quantities of the screws before and after the seating change greatly, so it is possible to determine the seating of the screws based on this change. In the case of (a) above, in a tightening tool including any of the above-described detection devices, a control device that controls a motor based on detection signals output from the first detection sensor and the second detection sensor. Further, the control device is required for the load shaft determined by the detection signals output from the first detection sensor and the second detection sensor to rotate in the screw tightening direction by the minimum resolution of the detection device. When the elapsed time exceeds the first predetermined value, it is preferable to stop the rotation of the motor after a predetermined time has elapsed from the timing when the first predetermined value was exceeded. With such a configuration, even when hammering or the like occurs before the screws are seated (for example, when the tapping screw is tightened), the seating of the screws is accurately detected, and the motor is driven for a predetermined time after the seating of the screws. The accuracy of the tightening torque of the screws can be improved by driving.

In the case of the above (b), the tightening tool provided with any of the above-mentioned detecting devices can have the following configuration, for example. That is, a control device for controlling the motor based on the detection signal output from the first detection sensor or the second detection sensor is provided, and the control device controls the time of the detection signal output from the first detection sensor. The state in which the interval exceeds the second predetermined value continues for the second predetermined number of times, or
Timing at which the second or third predetermined number of detection signals are output when the time interval of the detection signals output from the second detection sensor exceeds the third predetermined value for the third predetermined number of times It is preferable to stop the rotation of the motor after a lapse of a predetermined time from. Alternatively, the control device further includes a control device that controls the motor based on the detection signal output from the first detection sensor or the second detection sensor, and the control device controls the detection signal output from the first detection sensor. A state in which the difference in time interval exceeds a fourth predetermined value continues for a fourth predetermined number of times, or a state in which the difference in time interval of the detection signal output from the second detection sensor exceeds a fifth predetermined value is the fifth state. It is preferable to stop the rotation of the motor after a lapse of a predetermined time from the timing at which the last detection signal is output when the fourth or fifth predetermined number of times is continued, when the predetermined number of times is continued. Furthermore, a control device for controlling the motor based on a detection signal output from the first detection sensor or the second detection sensor is further provided, and the control device is a detection signal output from the first detection sensor. The state in which the amount of change in the time interval exceeds the sixth predetermined value continues for the sixth predetermined number of times, or the amount of change in the time interval of the detection signal output from the second detection sensor is set to the seventh predetermined value. When the value exceeding the value continues for the 7th predetermined number of times, the 6th or 7th
It is preferable to stop the rotation of the motor after a lapse of a predetermined time from the timing at which the last detection signal is output when the predetermined number of times has been continued.

Further, in the above case, the tightening tool provided with any of the above-mentioned detecting devices manages the tightening torque of the screws based on the number of times of the impact force generated after the screws are seated. You can also That is, the tightening tool includes an impact force detection unit that detects that an impact force is generated by the impact force generation mechanism, the first detection sensor, and the second detection sensor.
The control device controls the motor based on the detection signal output from the detection sensor and the presence or absence of the impact force detected by the impact force detection means. Then, the controller takes time required for the load shaft determined from the detection signals output from the first detection sensor and the second detection sensor to rotate in the screw tightening direction by the minimum resolution of the detection device. It is preferable to stop the rotation of the motor when is greater than the first predetermined value, and when the number of times of the impact force detected by the impact force detection means exceeds the first predetermined value and reaches the predetermined number. In the control device, the state in which the time interval at which the detection signal is output from the first detection sensor exceeds the second predetermined value continues for the second predetermined number of times, or the detection signal is output from the second detection sensor. When the output time interval exceeds the second predetermined value for a second predetermined number of times, the first
Alternatively, the rotation of the motor may be stopped when the number of times of the impact force detected by the impact force detection means reaches the predetermined number after the second predetermined number of detection signals are output. Further, the control device is configured such that a state in which the difference between the time intervals at which the detection signal is output from the first detection sensor exceeds a fourth predetermined value continues for a fourth predetermined number of times or is detected by the second detection sensor. When the difference between the time intervals at which the signals are output exceeds the fifth predetermined value for the fifth predetermined number of times, the detection signal of the fourth or fifth predetermined number of times is output and then detected by the impact force detection means. The rotation of the motor may be stopped when the number of times the impact force is applied reaches a predetermined number. Furthermore, the control device continues for a sixth predetermined number of times in which the amount of change over time in the time interval at which the detection signal is output from the first detection sensor exceeds a sixth predetermined value, or the second When the amount of change over time in the time interval at which the detection signal is output from the detection sensor exceeds the seventh predetermined value for the seventh predetermined number of times, the last detection signal when the sixth or seventh predetermined number of times continues The rotation of the motor may be stopped when the number of times of the impact force detected by the impact force detection means has reached a predetermined number after is output.

Further, in the above case, the tightening tool equipped with any of the above-mentioned detecting devices may manage the tightening torque of the screws by the rotation angle at which the load shaft rotates after the screws are seated. it can. That is, further comprising a control device that controls the motor based on the detection signals output from the first detection sensor and the second detection sensor,
The control device stops the rotation of the motor when the load shaft rotates a predetermined angle from the timing when it is determined that the screws are seated based on the detection signals output from the first detection sensor and the second detection sensor. It is preferable. Here, each of the above-described standards can be used as the standard for determining the seating of the screws.

As the impact force generating mechanism of the tightening tool which adopts the method of determining the motor stop timing by the above method, a mechanical impact force generating mechanism or an impact force generating mechanism utilizing hydraulic pressure such as an oil unit is used. Can be adopted. However, in the mechanical impact force generation mechanism, it is difficult to adjust the magnitude of the generated impact force unlike the hydraulic impact force reddening mechanism, so the above method works effectively. That is, the accuracy of the tightening torque of the screws can be improved by controlling the motor drive time from the seating of the screws and the number of times the impact force is generated.

Further, another tightening tool according to the present invention may have a structure described below. That is, the rotation of the motor is transmitted to the load shaft through the impact force generating mechanism, and the tightening tool that tightens the screw by rotating the load shaft detects the change in the rotation angle of the load shaft and detects the change in the load shaft. A rotation detection device that outputs a detection signal each time it rotates a predetermined angle,
And a control device that controls the motor based on the detection signal output from the rotation detection device. Then, the control device outputs the detection signal for the fifth predetermined number of times when the state in which the time interval at which the detection signal is output from the rotation detection device exceeds the fifth predetermined value continues for the fifth predetermined number of times. The rotation of the motor is stopped after a predetermined time has passed from the timing. In addition, in a tightening tool that tightens screws by rotating the load shaft by transmitting the rotation of the motor to the load shaft and detecting the change in the rotation angle of the load shaft, A rotation detection device that outputs a detection signal each time it rotates by a predetermined angle, an impact force detection unit that detects that an impact force is generated by the impact force generation mechanism, and a detection signal and an impact force output from the rotation detection device. And a control device that controls the motor based on the presence or absence of the impact force detected by the detection means. Then, the control device outputs the detection signal for the fifth predetermined number of times when the state in which the time interval at which the detection signal is output from the rotation detection device exceeds the fifth predetermined value continues for the fifth predetermined number of times. The rotation of the motor is stopped when the number of impact forces detected by the impact force detection means reaches a predetermined number. Alternatively, the rotation of the motor is transmitted to the load shaft via the impact force generation mechanism, and the tightening tool that tightens the screw by rotating the load shaft detects the change in the rotation angle of the load shaft and A rotation detection device that outputs a detection signal each time it rotates a predetermined angle, and a control device that controls the motor based on the detection signal output from the rotation detection device are provided. Then, the control device, when the state in which the amount of change over time in the time interval at which the detection signal is output from the rotation detection device exceeds the sixth predetermined value continues for the sixth predetermined number of times, continues for the sixth predetermined number of times. The rotation of the motor is stopped after a lapse of a predetermined time from the timing at which the last detection signal is output. Furthermore, the rotation of the motor is transmitted to the load shaft via the impact force generation mechanism, and the tightening tool that tightens the screw by rotating the load shaft detects the change in the rotation angle of the load shaft and detects the change in the load shaft. A rotation detection device that outputs a detection signal each time it rotates a predetermined angle, an impact force detection unit that detects that an impact force has been generated by the impact force generation mechanism, and a detection signal and an impact that are output from the rotation detection device. And a control device that controls the motor based on the presence or absence of the impact force detected by the force detection means. Then, the control device, when the state in which the amount of change over time in the time interval at which the detection signal is output from the rotation detection device exceeds the sixth predetermined value continues for the sixth predetermined number of times, continues for the sixth predetermined number of times. The rotation of the motor is stopped when the number of times of the impact force detected by the impact force detection means reaches a predetermined number after the detection signal of the last is detected.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The tightening tool described in each of the above claims can be suitably implemented in each of the following modes. (Mode 1) The impact force generation mechanism has an oil unit that generates an impact force on the load shaft, and the output shaft of the oil unit is the load shaft. In such a form, the maximum value of the impact force transmitted to the load shaft can be adjusted by adjusting the maximum pressure generated in the oil unit. In addition, damage to the oil unit caused by continuing driving of the oil unit is prevented.

[0016]

[Embodiment] Next, an angle soft impact wrench according to an embodiment of the present invention will be described. FIG. 1 shows a partial cross-sectional side view of an angle soft impact wrench. Angle soft impact wrench 1 shown in FIG.
A motor M (not shown in FIG. 1; however, shown in FIG. 6) as a drive source is housed and fixed in the housing 3. The planetary gear mechanism 18 is connected to the output shaft 20 of the motor M, and the buffer mechanism 14 is connected to the output shaft 16 of the planetary gear mechanism 18.
The oil unit 12 is connected via. The oil unit 12 is a known device that instantaneously generates a large impact force (oil pulse) on the output shaft 8 by utilizing the pressure of oil contained therein. The oil pulse generated in the oil unit 12 is adjusted so that a predetermined tightening torque can be obtained by adjusting the maximum pressure value of the oil contained inside. The buffer mechanism 14 is the oil unit 1
It is a known mechanism (for example, No. 7-31281, etc.) for preventing the shock when the oil pulse is generated due to 0 from being directly transmitted to the planetary gear mechanism 16 side.
The output shaft 8 of the oil unit 12 is rotatably supported by a bearing device 10, which will be described in detail later, and the bevel gear 6 is connected to the tip thereof. The bevel gear 6 meshes with a bevel gear 4 provided at one end of a spindle 2 which is axially supported by the output shaft 8 in an orthogonal manner. At the other end of the spindle 2, a socket (not shown) that engages with the head of a bolt or nut is attached. Therefore, when the motor M rotates in the angle soft impact wrench 1, the rotation is decelerated by the planetary gear mechanism 16 and transmitted to the oil unit 12. Oil unit 12
Since the load on the spindle 2 (output shaft 8) is low in the initial stage of tightening the nuts, the rotation transmitted from the motor 22 is transmitted to the spindle 2 as it is without generating an oil pulse. Therefore, the spindle 2 is continuously rotated, and accordingly, the screws are continuously tightened. On the other hand, when the screws are tightened and the load on the spindle 2 (output shaft 8) becomes high, an oil pulse is generated from the oil unit 12, and the screws are tightened by the impact force.

Next, the bearing device 10 that rotatably supports the output shaft 8 of the oil unit 12 that operates as described above will be described with reference to FIGS. Here, FIG. 2 is a cross-sectional view showing the structure of the bearing device, FIG. 3 is a diagram schematically showing the positional relationship between the magnet incorporated in the bearing device and the rotation angle detection sensor, and FIGS. It is a figure which respectively shows the state of the detection signal output from two rotation angle detection sensors, when the shaft 8 rotates normally or reversely. As shown in FIG. 2, the bearing device 10 includes an inner cylinder 30 and an outer cylinder 34 that rotatably supports the inner cylinder 30. The inner cylinder 30 is formed with an insertion hole having substantially the same diameter as the outer diameter of the output shaft 8 of the oil unit 12 (slightly smaller than the outer diameter of the output shaft 8). The output shaft 8 of the oil unit 12 is press-fitted into the insertion hole from the right end side of the drawing, and the inner cylinder 30 is fixed to the output shaft 8 by this. Therefore, when the output shaft 8 rotates, the inner cylinder 30 rotates together with the output shaft 8. A cylindrical magnet mounting member 40 is fixed to the right end of the inner cylinder 30 in the drawing. A plurality of magnets 42 (indicated by 42a, 42b, 42c, ... In FIG. 3) are arranged on the outer periphery of the magnet mounting member 40 at equal intervals. As shown in FIG. 3, the magnets 42 are magnets 42a, 4 arranged so that the S poles are on the outer peripheral side.
2c .. and magnets 42b .., arranged so that the N pole is on the outer peripheral side, and the S pole is on the outer peripheral side.
42c ... And the magnets 42b ... whose N poles are on the outer peripheral side are arranged alternately. The center angles between adjacent magnets (for example, the angle formed by the center of the magnet 42a, the center of the magnet 42b, and the center of rotation of the inner cylinder 30) are the same angle α °, as shown in FIG.

The outer cylinder 34 is a cylindrical member having an inner diameter larger than that of the inner cylinder 30 as shown in FIG. A ball 32 is interposed between the inner cylinder 30 and the outer cylinder 34, and the inner cylinder 30 is rotatably assembled to the outer cylinder 34. Therefore, when the outer cylinder 34 is housed and fixed in the housing 3, the inner cylinder 30 (that is, the output shaft 8) moves to the outer cylinder 34 (that is, the
It will be rotatably supported with respect to the housing 3). A cylindrical sensor mounting member 36 is fixed to the right end of the outer cylinder 34 in the drawing. On the inner wall surface of the sensor mounting member 36 facing the magnet 42, the rotation angle detection sensor 38a,
38b is provided (see FIG. 3). The rotation angle detection sensors 38a and 38b are latch type Hall ICs that detect changes in the magnetic field and switch the state of the detection signal. In the rotation angle detection sensors 38a and 38b, the state of the output signal becomes LOW level when the magnetic field of the S pole side acts, and the state of the output signal becomes HIGH level when the magnetic field of the N pole side acts.
Therefore, when the rotation angle detection sensors 38a, 38b are located at positions facing the magnets 42a, 42c, ... With the outer circumference on the S pole side, the state of the detection signals output from the rotation detection sensors 38a, 38b becomes LOW level, At the position facing the magnets 42b, ... With the N pole side as the outer peripheral side, the state of the detection signals output from the rotation angle detection sensors 38a, 38b becomes HIGH level.

Further, the rotation angle detecting sensors 38a, 38b
Are arranged at positions displaced by a central angle θ ° (θ = α ° / 2 in this embodiment), as well shown in FIG. Therefore, when the inner cylinder 30 (that is, the output shaft 8) rotates in the normal rotation direction, the state of the detection signals output from the rotation angle detection sensors 38a and 38b changes as shown in FIG. In order to specifically describe, for example, the rotation angle detection sensor 38a,
38b and the magnets 42a, 42b and 42c are in the state shown in FIG. In the state of FIG. 3, the rotation angle detection sensor 38
Since a is located at a position facing the magnet 42b (the N pole is on the outer peripheral side), the detection signal is at HIGH level. On the other hand, the rotation angle detection sensor 38b is connected to the magnet 42c that has already passed.
The detection signal is at the LOW level because (the S pole is on the outer peripheral side). When the inner cylinder 30 rotates by θ ° from this state, the magnet 42b (the N pole is on the outer peripheral side) comes to a position facing the rotation angle detection sensor 38b. Therefore, the detection signal output from the rotation angle detection sensor 38b switches from the LOW level to the HIGH level. At this time, the state of the detection signal of the rotation angle detection sensor 38a remains at the HIGH level. When the inner cylinder 30 is further rotated and the inner cylinder 30 is rotated by α ° from the state of FIG. 3, the magnet 42a (the S pole is on the outer peripheral side) comes to a position facing the rotation angle detection sensor 38a.
Therefore, the detection signal of the rotation angle detection sensor 38a is HIG.
It switches from H level to LOW level. Hereinafter, similarly, when the inner cylinder 30 (output shaft 8) rotates by the angle θ ° after the state of the detection signal of the rotation angle detection sensor 38a switches, the state of the detection signal of the rotation angle detection sensor 38b switches. Become. When the output shaft 8 rotates in the reverse rotation direction, the rotation angle detection sensor 38 is reversed, contrary to the above case.
The detection signals of a and 38b change as shown in FIG. That is, when the output shaft 8 further rotates by the angle θ ° after the state of the detection signal of the rotation angle detection sensor 38b is switched, the state of the detection signal of the rotation angle detection sensor 38a is switched.

As is clear from the above description, the rotation angle detection sensors 38a and 38b switch the level of the detection signal each time the inner cylinder 30 (that is, the output shaft 8 of the oil unit 12) rotates by α °. Therefore, the rotation angle detection sensors 38a and 38b are set to 1 each time the output shaft 8 rotates 2 × α °.
The microcomputer 50, which will be described later, detects the rising edge and the falling edge of the pulse wave and detects the change in the rotation angle of the output shaft 8. Therefore, if the edge of the pulse wave cannot be detected even if the output shaft 8 rotates (regardless of whether the output shaft 8 rotates forward or backward), the output shaft 8
The change in the rotation angle of is 0 °. That is, the minimum resolution of the rotation angle change (forward rotation direction and reverse rotation direction) of the output shaft 8 that can be detected by the rotation angle detection sensors 38a and 38b is 2 × α °. Further, the detection signals output from the two rotation angle detection sensors 38a and 38b are out of phase by θ °, and the direction in which the phases are deviated differs depending on the rotation direction of the output shaft 8. Therefore, the rotation direction of the output shaft 8 is detected by the phase shift of the detection signals output from the rotation angle detection sensors 38a and 38b. That is, the determination is made based on the input order of the detection signals (rising edge and falling edge) of the rotation angle detection sensor 38a and the detection signals (rising edge and falling edge) of the rotation angle detection sensor 38b. The detection signal shown in FIG. 8 will be specifically described as an example. In the example of FIG. 8, since the output shaft 8 is hammered within a narrow angle range, only the detection signal output from the one rotation angle detection sensor 38b becomes a pulse wave and the period during which the microcomputer 50 detects the signal is a period. Has occurred. First, the microcomputer 50 detects the rising edge of the detection signal from the rotation angle detection sensor 38a at time t1, and then detects the rising edge of the detection signal from the rotation angle detection sensor 38b at time t2. Therefore, at time t2, it is determined that the output shaft 8 is rotating normally. Further, at time t3, the falling edge of the detection signal from the rotation angle detection sensor 38a is detected, and thereafter, at time t4, the falling edge of the detection signal from the rotation angle detection sensor 38b is detected. For this reason, it is determined that the output shaft 8 is also rotating normally at times t3 and t4. On the other hand, at time t5, the rising edge of the detection signal from the rotation angle detection sensor 38b is detected. Therefore,
If the output shaft 8 is rotating in the forward direction, the rising edge from the rotation detection sensor 38a, which should be detected, is not detected, and the rising edge of the detection signal from the rotation angle detection sensor 38b is detected. It is determined that 8 is reversed. Similarly, at time t6, it is determined that the output shaft 8 is rotating normally, at time t7, it is determined that the output shaft 8 is rotating in the reverse direction, and at time t8, it is determined that the output shaft 8 is rotating normally. To be done. Then, at time t9, the rotation angle detection sensor 38a
Since the rising edge of the detection signal from is detected, it is determined that the output shaft 8 is rotating in the normal direction and that the output shaft is rotated in the normal direction by the minimum resolution. Time t1
Since the detection signals (rising edge and falling edge) detected at 0, t11, and t12 are in the order when the output shaft 8 is rotating normally, it is determined that the output shaft 8 is rotating normally. .

Angle soft impact wrench 1
Is provided with a trigger switch 22 for starting the motor M, and a battery pack 24 for supplying electric power to the motor M, the microcomputer 50 described below, and the like is detachably attached to the lower end of the housing 3. Has been.

Next, the structure of the control circuit of the angle soft impact wrench 1 will be described with reference to FIG. The control circuit of the angle soft impact wrench 1 according to the present embodiment mainly includes a microcomputer 50 housed in the housing 3. The microcomputer 50 includes a CPU 52, a ROM 54, a RAM 56 and an I / O 58.
It is a microcomputer in the form of a chip and is connected as shown in FIG. The ROM 54 of the microcomputer 50 stores a control program for automatically stopping the driving of the motor M, which will be described in detail later.
The rotation angle detection sensors (Hall IC) 38a, 38 described above
b is connected to a predetermined input port of the I / O 58, and the detection signals output from the rotation angle detection sensors 38a and 38b are input to the microcomputer 50. The battery pack 24, which is a power supply, is connected to the microcomputer 50 via a power supply circuit 64 and to the motor M via a drive circuit 62. Further, the motor M is controlled by the microcomputer 50 via the drive circuit 62 and the brake circuit 60.
When the motor M is driven, the output shaft 8 of the oil unit 12
Rotates, and the rotation angle detection sensors 38a, 38
A detection signal is input to the microcomputer 50 from b. The microcomputer 50 performs the process described below based on the input detection signal, and operates the brake circuit 60 at a predetermined timing to stop the motor M.

Next, the processing of the microcomputer 50 when tightening the nuts using the angle soft impact wrench 1 having the above-mentioned structure will be described with reference to the flow chart shown in FIG. FIG. 7 shows a flowchart of processing performed by the microcomputer 50. In order to tighten the nuts using the angle soft impact wrench 1, first, the operator engages the nuts with the socket attached to the tip of the spindle 2 and turns on the trigger switch 22. Trigger switch 2
When 2 is turned on, the microcomputer 50 starts the rotational driving of the motor M and performs the processing described below. In this embodiment, the trigger switch 22 is turned on.
Immediately after that, do not drive the motor M with maximum power,
Within a predetermined time after the trigger switch 22 is turned on, control for gradually increasing the rotation speed of the motor M (hereinafter referred to as soft start) is performed. The process for this soft start is
Since the processing is the same as the conventionally known processing, the procedure for stopping the driving of the motor M will be mainly described here.

When the trigger switch 22 is turned on, FIG.
As shown in, the microcomputer 50 first resets the auto stop timer and starts counting (step S10). The auto stop timer is a timer for determining whether or not to stop the motor M, and stops the driving of the motor M when the auto stop timer reaches a preset set value as described later. When the auto stop timer is initialized, the soft start timer is then reset and counting is started (step S12). The soft start timer is a timer for determining whether or not the motor M is drive-controlled by soft start. In step S14, the value of the variable R that stores the reverse rotation amount of the output shaft 8 is cleared (step S14). next,
It is determined whether the trigger switch 22 is ON (step S16). If the trigger switch 22 is not in the ON state [NO in step S16], step S42
And the motor M is stopped (step S42). Therefore, when the operator who turns on the trigger switch 22 turns off the trigger switch 22 during the screw tightening work, the motor M is stopped even during the tightening work. On the other hand, when the trigger switch 22 is in the ON state [YES in step S16], the rotation angle detection sensor 38
The state of the detection signals output from a and 38b is confirmed (step S18). Specifically, the rotation angle detection sensor 3
By checking the state of the input port to which the detection signals of 8a and 38b are input, it is checked whether or not the pulse edge of the detection signal is detected.

In step S20, it is determined whether or not the pulse edge of the detection signal has been detected by the process of step S18 (step S20). Rotation angle detection sensor 38
When the pulse edge of the detection signal output from a or 38b is not detected [NO in step S20]
Determines whether or not the soft start is completed (step S36). Specifically, it is determined whether or not the soft start timer, which has started counting in step S12, has exceeded a predetermined time (time to drive the motor M by soft start). If the soft start is completed [YES in step S36], the process proceeds to step S40. On the other hand, if the soft start is not completed [NO in step S36], the process proceeds to step S35, the auto stop timer is reset and restarted, and then the process returns to step S16 to repeat the process from step S16. Therefore, in this embodiment, the auto stop timer is reset and the motor M is not automatically stopped by the microcomputer 50 when the soft start is not completed. When the process proceeds to step S40, it is determined whether the auto stop timer matches the set value (step S40). When the auto stop timer is equal to or greater than the set value [YES in step S40], the motor M is stopped (step S42), and when the auto stop timer does not match the set value [N in step S40]
In the case of O], the process returns to step S16, and step S16
The process from is repeated.

On the other hand, when the pulse edge of the detection signal output from the rotation angle detection sensor 38a or 38b is detected by the processing of step S20 described above [step S2
When 0 is YES], it is determined whether or not the rotation direction of the output shaft 8 is the forward rotation direction (step S24). Specifically, the determination is made based on the phase difference between the detected detection signal (pulse edge) of the rotation angle detection sensor 38a and the detected signal (pulse edge) of the rotation angle detection sensor 38b. That is, as shown in FIG. 4, when the detection signal of the rotation angle detection sensor 38b is delayed by θ °, it is determined that the output shaft 8 has rotated in the normal direction, and as shown in FIG. 5, the detection signal of the rotation angle detection sensor 38a is θ °. When it is delayed by a certain amount, it is determined that the output shaft 8 has reversed.

When the output shaft 8 is not rotating in the forward direction [NO in step S24], the output shaft 8 is rotating in the reverse direction, so 1 is added to the variable R for storing the reverse rotation amount. (Step S26). After that, the process proceeds to step S36, and the same process as the above-mentioned process is performed. Therefore, if the soft start is completed, the auto stop timer is not reset and the step S
40 determinations will be made.

On the contrary, when the output shaft 8 is rotating in the forward direction [YES in step S24], it is determined whether or not the stored reverse rotation amount R is 0 (step S3).
0). That is, in the tightening tool, the output shaft 8 repeats normal rotation and reverse rotation due to rattling of the socket and hammering action. Therefore, even if the output shaft 8 rotates in the forward direction, whether the nuts are tightened by that (whether the nuts are rotated) or whether the output shaft 8 is returned to its original position by a hammering action or the like is determined. It cannot be judged. Therefore, by determining whether or not the stored reverse rotation amount R is 0, it is determined whether or not the screw tightening is performed by the rotation in the normal rotation direction. When the stored reverse rotation amount R is not 0 [NO in step S30], the process proceeds to step S32, 1 is subtracted from the reverse rotation amount R (step S32), and the process proceeds to step S36. That is, when the reverse rotation amount R is not 0, the nuts are not tightened due to the rotation of the output shaft 8, and it is determined that the nuts are stopped. Therefore, if the soft start is completed, the automatic stop timer is determined. On the other hand, when the stored reverse rotation amount R is 0 [YES in step S30], it is determined that the screw has been tightened and rotated by the rotation of the output shaft 8 in the forward rotation direction, and the automatic stop timer is reset and restarted. After performing (step S35), the process returns to step S16 and the process from step S16 is repeated.

As is apparent from the above description, in the angle soft impact wrench 1 of this embodiment, the motor M is driven when the trigger switch 22 is turned ON, and at the same time, the output shaft 8 is detected by the detection signals of the rotation angle detection sensors 38a and 38b. The rotation angle change and the rotation direction of are detected. The auto stop timer is reset and the motor M is driven as long as the output shaft 8 rotates in the normal direction. When the output shaft 8 stops rotating, the auto stop timer starts counting and the motor M is automatically driven. Controlled to stop.
Here, when the output shaft 8 repeats the reverse rotation and the normal rotation by hammering, the reverse rotation amount R is obtained from the detected rotation direction of the output shaft 8 and it is determined whether or not the screws are stopped. Then, even if the rotation in the forward rotation direction is detected, the reverse rotation amount R is 0.
Unless (normal rotation from the original position), it is determined that the screws are stopped, and the auto-stop timer continues counting. Therefore, even if the reverse rotation and the normal rotation are repeated by hammering, the drive of the motor M is stopped after the set time has elapsed as long as the screws are stopped. Therefore, it is possible to prevent the screws from being overtightened, and it is possible to accurately control the tightening torque of the screws. Particularly, in the angle soft impact wrench 1 of this embodiment, since the oil unit 10 is used as a device for generating an impact force, the impact force applied to the output shaft 8 can be controlled to a constant value, and tightening can be performed. The torque accuracy can be further improved. Further, since the auto stop function does not work during the soft start, even if the rotation of the screws is stopped during the soft start, the motor M is driven and stopped for the set time after the end of the soft start. Therefore, the set impact force acts on the screw,
The soft start function prevents the tightening torque from decreasing in accuracy. Further, in the present embodiment, the bearing device 1
By arranging the rotation angle detection sensors 38a and 38b at 0, the positional relationship between the rotation angle detection sensors 38a and 38b and the clearance between the rotation angle detection sensors 38a and 38b and the output shaft 8 are kept substantially constant. Be drunk Therefore, the rotation direction and the rotation angle change of the output shaft 8 can be accurately detected.

(Embodiment 2) Next, a tightening tool (angle soft impact wrench) according to a second embodiment of the present invention will be described with reference to the drawings. The tightening tool according to the second embodiment has the same mechanical structure as the tightening tool according to the first embodiment. However, the second embodiment is different from the first embodiment in that the timer is started from the timing when the seating of the screws is detected and the motor is stopped when the timer reaches the set time. Therefore, regarding the mechanical configuration of the tightening tool according to the second embodiment, the reference numerals of the first embodiment are used and the description thereof is omitted, and only the points different from the first embodiment will be described.

In the tightening tool of the second embodiment, the time intervals (ΔTa, ΔTb) of the detection signals (pulse edges) output from the rotation angle detection sensors 38a, 38b and the output shaft 8 are set by the rotation angle detection sensors. 38a, 38b minimum resolution (2 × α
The time (ΔTc,
The seating of the screws is detected based on ΔTd). That is, in the second embodiment, attention is paid to the fact that the above ΔTa, ΔTb, ΔTc, and ΔTd greatly change before and after the seating of the screws, and the seating of the screws (stop timing of the motor M) is determined based on these. To control the tightening torque of screws. Here, the relationship between the detection signals of the rotation angle detection sensors 38a and 38b and the above ΔTa, ΔTb, ΔTc, and ΔTd is shown in FIG.
Is schematically shown. As is clear from FIG. 8, ΔT
a and ΔTb are times measured without considering the rotation direction of the output shaft 8, and ΔTc and ΔTd are times measured with consideration of the rotation direction of the output shaft 8. The reason why the seating is determined using ΔTa and ΔTb is to determine the seating of a tapping screw or the like where an impact force is generated before the seating, and ΔTc and ΔTb
The reason for determining the seating using Td is to determine the seating of a normal mechanical screw in which an impact force is generated after the seating. This is because in the case of a tapping screw or the like, a certain amount of load acts on the output shaft from the initial stage of tightening the screw, and even if ΔTc and ΔTd are monitored, the change is small before and after seating. Also, in the case of ordinary mechanical screws, the output shaft 8 rotates at a substantially constant speed until the screws are seated, and the rotational speed of the output shaft 8 rapidly decreases after seating. Therefore, ΔTc and ΔTd should be monitored. The seating of screws can be detected with high accuracy.

Microcomputer 5 according to the second embodiment
9 and 10 show flowcharts of the processing performed in 0. As shown in FIG. 9, when the trigger switch 22 is turned on, the microcomputer 50 first sets ΔTa and ΔT.
The timers for measuring b, ΔTc, and ΔTd are reset to start counting (step S101), and the soft start timer is reset to start counting (step S103). When each timer is initialized, the value of the variable R that stores the reverse rotation amount of the output shaft 8 is cleared (step S105). Also, the number of judgments N
The values of a and Nb are reset (step S107). The number of determinations Na is incremented by 1 when ΔTa exceeds a predetermined threshold value T1, and cleared when ΔTa does not exceed it. Similarly, the determination count Nb is incremented by 1 when ΔTb exceeds a predetermined threshold T1, and cleared when ΔTb does not exceed. Therefore, the determination times Na and Nb are the times at which ΔTa and ΔTb successively exceed the threshold value T1.

Next, it is determined whether or not the trigger switch 22 is ON (step S109). Trigger switch 2
If 2 is not in the ON state [NO in step S109], the process proceeds to step S165 in FIG. 10 to stop the motor M. On the other hand, when the trigger switch 22 is in the ON state [YES in step S109], the state of the detection signals output from the rotation angle detection sensors 38a and 38b is confirmed (step S111). In step S113,
It is determined whether or not the pulse edge of the detection signal has been detected by the process of step S111. Rotation angle detection sensor 3
When the pulse edge of the detection signal output from 8a or 38b is not detected [NO in step S113], the process proceeds to step S115 to determine whether or not the soft start is completed.

When the soft start is completed [YES in step S115], the process proceeds to step S157. On the other hand, if the soft start is not completed [NO in step S115], the flow advances to step S133 to reset ΔTa, ΔTb, ΔTc, and ΔTd and restart. When step S133 ends, the process returns to step S109 and the processes from step S109 are repeated. Therefore, also in the second embodiment, in the state where the soft start is not completed, the microcomputer 5
The motor M is not automatically stopped by 0.
When the process proceeds to step S157, it is determined whether ΔTc or ΔTd exceeds a predetermined threshold value T2. If ΔTc or ΔTd does not exceed the threshold value T2 [NO in step S40], the process returns to step S109 and the process from step S109 is repeated. On the other hand, when ΔTc or ΔTd exceeds the threshold value T2 [YES in step S157], it is determined that the screws are seated and the motor stop process is performed (step S1).
59).

The motor stop processing in step S159 will be described with reference to FIG. In the motor stop process, first, the seated timer is reset and started (step S161). There is a pair of seated timers for measuring the motor drive time after the screws are seated. Step S163
Then, it is determined whether or not the post-seating timer started in step S161 exceeds the set time. When the seated timer is longer than the set time [step S163
If YES in step S.], the motor M is stopped, and if the after-seating timer is less than the set time [YES in step S163], the process waits until the after-seat timer reaches or exceeds the set time. Therefore, when it is determined that the screws are seated in step S157 of FIG. 9 (that is, YES in step S157), the motor M is stopped when the set time has elapsed from that time. Therefore, the tightening torque accuracy of the screws can be improved by driving the motor M for a set time after the screws are seated.

When the pulse edge of the detection signal output from the rotation angle detection sensor 38a or 38b is detected by the process of step S113 [YES in step S113.
In case of], it is determined whether or not the rotation direction of the output shaft 8 is the forward rotation direction (step S117). When the output shaft 8 does not rotate in the forward direction [NO in step S117]
Means that the output shaft 8 is rotating in the reverse rotation direction, so 1 is added to the variable R that stores the reverse rotation amount (step S119). On the contrary, when the output shaft 8 is rotating in the forward direction [YES in step S117], the stored reverse rotation amount R
Is determined to be 0 (step S121). When the stored reverse rotation amount R is not 0 [NO in step S121], 1 is subtracted from the reverse rotation amount R (step S12).
3). On the other hand, when the stored reverse rotation amount R is 0 [YES in step S121], it is determined whether the detection signal detected in step S113 is the detection signal from the rotation angle detection sensor 38a (S125). Rotation angle detection sensor 3
If the detection signal is output from 8a [step S1
If YES in 25], ΔTc is reset and restarted (S127). If it is output from the rotation angle detection sensor 38b (NO in step S125), ΔTd is reset and restarted ( S12
9). Therefore, when the output shaft 8 does not rotate in the forward rotation direction beyond the rotation angle in the reverse rotation direction, ΔTc and ΔTd are not reset, and the count is continued. Therefore, even if hammering or the like occurs, the seating of the screws can be accurately detected.

In step S131, it is determined whether or not the soft start is completed. If the soft start is completed [YES in step S131], the process proceeds to step S135. On the other hand, if the soft start has not been completed [NO in step S131], the flow advances to step S133 to reset ΔTa, ΔTb, ΔTc, and ΔTd and restart. When step S133 ends, the process returns to step S109 and returns to step S109.
The process from is repeated.

In step S135, first, the detection signal detected in step S111 is the rotation angle detection sensor 3
It is determined whether or not the detection signal is output from 8a (step S135). When the detection signal detected in step S111 is the detection signal output from the rotation angle detection sensor 38a [in the case of YES in step S135]
Determines whether ΔTa exceeds a predetermined threshold T1 (S137). If ΔTa does not exceed the predetermined threshold value T1 [NO in step S137], the determination count Na is reset (S143) and the process proceeds to step S145.
When ΔTa exceeds a predetermined threshold value T1 [step S13
If YES in 7], it is further determined whether or not the value of the determination number Na is "1" (S139). Number of judgments Na
If the value of is not "1" [NO in step 139], the determination count Na is set to "1" (step S14
1) If the number of determinations Na is “1” [step S139
If YES, the process proceeds to step S159 and the motor M
To stop. Therefore, in the present embodiment, the motor M cannot be stopped unless the number of times ΔTa exceeds the threshold value T1 continues for a predetermined number of times (two times in the present embodiment). Therefore, even if ΔTa temporarily exceeds the threshold value T1 due to burrs or the like, the motor M is not stopped. When the operation proceeds to step S145, the rotation detection sensor 38a
In order to measure the time from when the detection signal to be output next is received, ΔTa is reset and restarted (step S145). Then, the process proceeds to step S157 already described.

On the other hand, when the detection signal detected in step S111 is the detection signal output from the rotation angle detection sensor 38b [NO in step S135], ΔT
It is determined whether or not b exceeds a predetermined threshold T1 (S1
47). When ΔTb does not exceed the predetermined threshold value T1 [NO in step S147], the determination count Nb is reset (S153), and the process proceeds to step S155. When ΔTb exceeds a predetermined threshold value T1 [YE in step S147]
In the case of S], it is further determined whether or not the number of determinations Nb is "1" (S149). If the determination number Nb is not "1" [NO in step 149], the determination number Nb is set to "1" (step S151), and if the determination number Nb is "1" [YES in step S149], the step is performed. In step S159, the motor stop process is performed. Therefore, as in the case of ΔTa described above, the motor M is not stopped unless the number of times ΔTb exceeds the threshold value T1 continues for a predetermined number of times (two times in this embodiment). In step S155, ΔTb is reset and restarted in order to measure the time until the detection signal output next from the rotation detection sensor 38b is received (step S155).
Then, the process proceeds to step S157 already described.

According to the second embodiment described above, ΔTa, Δ
The seating of screws is detected from the time measured by four timers Tb, ΔTc, and ΔTd, and the motor M is driven for a set time after the seating of screws is detected. Can be improved. Also, since the seating of screws is detected by four timers, ΔTa, ΔTb, ΔTc, and ΔTd, both types of screws such as tapping screws that generate impact force before seating and mechanical screws that generate impact force after seating. It is possible to accurately detect the sitting of a class.

In the second embodiment described above, the time interval ΔTa of the detection signal output from the rotation angle detection sensor 38a is set.
The stop timing of the motor M is determined based on the time interval ΔTb of the detection signal output from the rotation angle detection sensor 38b, but in addition to this, for example, the difference of ΔTa (one before the measured ΔTa. It is also possible to determine the stop timing of the motor M based on the difference between the measured ΔTa) and the difference between the ΔTb (the measured ΔTa minus the immediately preceding measured ΔTa). ΔTa,
By using the difference of ΔTb as a reference, the changes in ΔTa and ΔTb before and after seating become clearer, and the seating of screws can be detected with good accuracy. That is, by using the difference between ΔTa and ΔTb as a reference, the motor M may be changed due to voltage fluctuation or the like.
The seating of the screws can be accurately detected even when the number of revolutions changes and the rotation speed of the output shaft 8 changes.

The motor M is based on the difference between ΔTa and ΔTb.
FIG. 11 shows a flowchart for determining the stop timing of. As is apparent from FIG. 11, the flowchart shown in FIG. 11 is substantially the same as that shown in FIG. 9, and is a process for simply calculating the difference between ΔTa and ΔTb (step S203, steps S239 to S251, step S2).
53 to S265) is different from that shown in FIG. Only different parts will be described below. The motor stop process of step S269 in FIG. 11 is the same as the motor stop process shown in FIG.
The description of the motor stop process of 9 is omitted. If NO in step S211 in FIG.
The same applies to the case of 0 in step S165.

Step S203 is for saving ΔTa and ΔTb.
This is a process of resetting (ΔTa, ΔTb measured immediately before). As will be described later, when ΔTa and ΔTb are measured, ΔTa and ΔTb measured immediately before are subtracted from the measured ΔTa and ΔTb to obtain the difference between ΔTa and ΔTb. With reference to FIG. 8, for example, when ΔTb (j) is measured, ΔTb (j−1) measured immediately before is subtracted from the ΔTb (j) to calculate the difference of ΔTb. Therefore, in the processing of step S203, ΔTa and ΔTb measured and stored immediately before are reset.

The processing of steps S239 to S251 is processing when the detection signal output from the rotation angle detection sensor 38a is detected by the microcomputer 50. In step S239, it is determined whether the stored ΔTa is “0” (S137). That is, since the difference in ΔTa cannot be calculated during the first ΔTa measurement after the saving ΔTa is reset in step S203, it is first determined whether or not the saving ΔTa is “0”. When ΔTa for storage is “0” [step S239
In case of YES], the judgment number Na is reset (S
247), the currently counted ΔTa (i) is replaced with the saving ΔTa (S249). With this, when the detection signal from the rotation angle detection sensor 38a is detected next time, the difference of ΔTa can be calculated. When step S249 ends, the Δ that is currently counted is
Ta (i) is reset and the process proceeds to step S267. Therefore, if ΔTc and ΔTd do not exceed the threshold value T2, the process returns to step S211, and the processing from step S211 is repeated.

On the other hand, when the storage ΔTa is not "0" [NO in step S239], the value obtained by subtracting the stored ΔTa from the currently counting ΔTa (i) (that is, the difference of ΔTa) ) Exceeds a predetermined threshold T3 (step S241). ΔTa
If (i) -ΔTa does not exceed the threshold value T3 [NO in step S241], the process proceeds to step S247 and the process from step S247 is repeated. Therefore, the determination count Na is reset, the storage ΔTa is updated, and the currently counting ΔTa is reset. On the contrary, when ΔTa (i) −ΔTa exceeds the threshold value T3 [YES in step S241], it is further determined whether or not the value of the determination count Na is “1” (S243).
When the value of the judgment number Na is not "1" [step 243]
In the case of NO], the number of determinations Na is set to "1" (step S245), and the process proceeds to step S251. On the contrary, when the determination number Na is "1" [YES in step S243], the process proceeds to the motor stop process of step S269. Therefore, even in the case shown in FIG. 11, as in the second embodiment,
If the number of times ΔTa (i) −ΔTa exceeds the threshold value T3 does not reach the predetermined number (two times in this example), the motor M cannot be stopped.

The processing of steps S253 to S265 is processing when the detection signal output from the rotation angle detection sensor 38b is detected by the microcomputer 50. This processing is basically the above-described steps S239-
Since it is the same as the processing of S251 and is simply the difference between ΔTa and ΔTb, its detailed description is omitted.

Although some embodiments of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. For example, in the above-described first embodiment, the rotation of the motor M is stopped when it is determined that the rotation of the screws has stopped, but the rotation of the motor M occurs when a predetermined time has elapsed after the screws stopped. May be stopped. In this case, since the tightening of the screw is continued for a predetermined time after the rotation is stopped, the tightening torque is further prevented from being insufficient. Even if the screw rotation does not stop completely, such as when tightening a wood screw, the timer setting value can be adjusted to stop the motor when the screw rotation speed falls below a certain value. It is possible to make it the form. Furthermore, the present invention is not limited to such an example, and is applicable to a tightening tool that counts the number of impact forces (striking) applied to a load shaft and stops driving the motor M when the number of striking reaches a predetermined number. It can also be applied. In such a tightening tool, for example, an impact detection sensor that detects an impact applied to the load shaft is separately provided. Then, similarly to each of the above-described embodiments, the rotation stop of the screws is judged from the rotation direction and the rotation angle change of the load shaft, and the number of hits detected by the hit detection sensor after the screws stop rotating is the set number. Stops driving the motor only when counted. According to such a configuration, even if a hit occurs before the screws are seated due to burrs or the like, the hit before the seat is not counted, and the load shaft is hit a predetermined number of times after the screws are seated. Motor stops. Therefore, the tightening torque of the screws is constant, and the accuracy of the tightening torque can be improved. Further, although the oil unit is used for the impact force generation mechanism in the above-mentioned embodiment, as the mechanism for generating the impact force,
The present invention can also be applied to various other mechanisms, for example, a tightening tool having a mechanical impact force generating mechanism that strikes the anvil with a hammer. Further, in the case of a tool having a function of switching between normal rotation / reverse rotation, by comparing the input of the changeover switch with the rotation direction of the output shaft by the rotation angle detection sensors 38a, 38b, it is possible to prevent wiring mistakes during assembly. An abnormal condition can be found. Further, the seating of the screws is determined by the change with time of the time interval of the detection signal output from the rotation angle detection sensor (that is, the rotation acceleration obtained by further differentiating the rotation speed of the output shaft determined by the time interval of the detection signal). You can Since the rotational acceleration of the output shaft largely changes before and after the screws are seated, it is possible to detect the seating of the screws using this. Also,
In the second embodiment described above, the motor is stopped and then the motor is stopped for a set time, but the invention is not limited to such an example, and the impact force generated after the screws are seated is not limited to this example. The motor may be stopped when the number of times reaches the set number. With such a configuration, the tightening torque of the screws is highly likely to be proportional to the number of times the impact force is generated (the number of times after the seat is seated) (for example, a tightening tool having a mechanical impact force generation mechanism). Is effective against. Further, it is possible to stop the motor when the output shaft rotates by a set angle after the screws are seated. Since the tightening torque of the screws is determined by the rotation angle after the screws are seated and the material of the member to be tightened, such a configuration is an effective method for all tightening tools.

Further, the technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Further, the technique illustrated in the present specification or the drawings achieves a plurality of purposes at the same time, and achieving the one purpose among them has technical utility.

[Brief description of drawings]

FIG. 1 is a partial sectional side view of an angle soft impact wrench according to the present embodiment.

FIG. 2 is a sectional view showing the structure of the bearing device.

FIG. 3 is a diagram schematically showing a positional relationship between a magnet incorporated in the bearing device and a rotation angle detection sensor.

FIG. 4 is a diagram showing a state of detection signals output from two rotation angle detection sensors when the output shaft rotates in the normal direction.

FIG. 5 is a diagram showing a state of detection signals output from two rotation angle detection sensors when the output shaft rotates in the reverse direction.

FIG. 6 is a block diagram showing a configuration of a control circuit of the angle soft impact wrench.

FIG. 7 is a flowchart of motor auto stop processing performed by a microcomputer.

FIG. 8 is a diagram schematically showing the relationship between detection signals of rotation angle detection sensors 38a and 38b and ΔTa, ΔTb, ΔTc, and ΔTd.

FIG. 9 is a flowchart of motor auto stop processing performed by the microcomputer of the second embodiment.

FIG. 10 is a flowchart of motor stop processing.

FIG. 11 is a flowchart of a motor auto stop process that is a modification of the second embodiment.

[Explanation of symbols]

1 ... Angle soft impact wrench 8 ... Output shaft 10 ... Bearing device 12 ... Oil unit 22..Trigger switch 30 ... Inner cylinder 34 ... Outer cylinder 36..Sensor mounting member 38a, 38b ... Rotation angle detection sensor 40..Magnet mounting member 42 ... Magnet

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Manabu Tokunaga             3-11-8 Sumiyoshi-cho, Anjo City, Aichi Stock             Company Makita F-term (reference) 3C038 AA01 BC04 CA05 EA06

Claims (11)

[Claims] 1. A tightening tool for tightening a screw by transmitting the rotation of a motor to a load shaft through an impact force generating mechanism and rotating the load shaft to change a rotation direction and a rotation angle of the load shaft. A tightening tool comprising a detection device for detecting. 2. The detection device includes a first detection sensor that detects a change in the rotation angle of the load shaft, and a second detection sensor that detects a change in the rotation angle of the load shaft. The detection signal output from the sensor and the detection signal output from the second detection sensor are the first when the load shaft rotates in the forward direction.
2. The tightening tool according to claim 1, wherein the tightening tool shifts by a second phase angle when the load axis reverses, and the shift angle shifts by a second phase angle. 3. A bearing device for rotatably supporting the load shaft is further provided, and the bearing device includes an inner cylinder part fixed to the load shaft and an outer cylinder part rotatably supporting the inner cylinder part. And the first detection sensor and the second
The tightening tool according to claim 2, wherein the detection sensor is provided. 4. A control device for controlling the rotation of the motor to stop after a predetermined time from the timing when it is determined that the rotation of the load shaft has stopped based on the rotation direction and the rotation angle change of the load shaft detected by the detection device. The tightening tool according to any one of claims 1 to 3, further comprising: 5. The control device is configured such that a load shaft rotates alternately in a screw tightening direction and a screw loosening direction, and a rotation angle change in the screw tightening direction does not exceed a rotation angle change in the screw loosening direction continues for a predetermined time. The tightening tool according to claim 4, wherein the rotation of the motor is stopped when the tightening is performed. 6. A control device for controlling a motor based on detection signals output from the first detection sensor and the second detection sensor, the control device comprising the first detection sensor and the second detection sensor. When the time required for the load shaft, which is determined from the detection signal output from the detection sensor of the above, to rotate in the screw tightening direction by the minimum resolution of the detection device exceeds the first predetermined value, the first predetermined value The tightening tool according to claim 2 or 3, wherein the rotation of the motor is stopped after a predetermined time has elapsed from the timing of exceeding. 7. An impact force detecting means for detecting that an impact force is generated by the impact force generating mechanism, a detection signal output from the first detection sensor and a second detection sensor, and an impact force detecting means. A control device for controlling the motor based on the presence or absence of the detected impact force is further provided, and the control device is a load determined from the detection signals output from the first detection sensor and the second detection sensor. When the time required for the shaft to rotate in the screw tightening direction by the minimum resolution of the detection device exceeds the first predetermined value, the impact force detected by the impact force detection means after exceeding the first predetermined value. The tightening tool according to claim 2 or 3, wherein the rotation of the motor is stopped at a timing when the number of times reaches a predetermined number. 8. A control device for controlling a motor based on a detection signal output from the first detection sensor or the second detection sensor, the control device output from the first detection sensor. The state in which the time interval of the detection signal exceeds the second predetermined value continues for the second predetermined number of times, or the time interval of the detection signal output from the second detection sensor exceeds the third predetermined value in the third state. The tightening according to claim 2 or 3, wherein when the predetermined number of times is continued, the rotation of the motor is stopped after a predetermined time elapses from the timing when the detection signal of the second or third predetermined number of times is output. tool. 9. A control device that controls a motor based on a detection signal output from the first detection sensor or the second detection sensor, wherein the control device outputs from the first detection sensor. The state in which the difference between the time intervals of the detection signals exceeds the fourth predetermined value continues for the fourth predetermined number of times, or the difference between the time intervals of the detection signals output from the second detection sensor exceeds the fifth predetermined value. 7. When the state continues for a fifth predetermined number of times, the rotation of the motor is stopped after a predetermined time has elapsed from the timing at which the last detection signal when the fourth or fifth predetermined number of times continued was output. The tightening tool according to 2 or 3. 10. A control device for controlling a motor based on a detection signal output from the first detection sensor or the second detection sensor, the control device being output from the first detection sensor. The state in which the amount of change in the time interval of the detection signal exceeds the sixth predetermined value continues for the sixth predetermined number of times, or the amount of change in the time interval of the detection signal output from the second detection sensor with time. When the state of exceeding the seventh predetermined value continues for the seventh predetermined number of times, the rotation of the motor is stopped after a predetermined time elapses from the timing at which the last detection signal is output when the sixth or seventh predetermined number of times continues. The tightening tool according to claim 2 or 3, characterized in that. 11. A control device for controlling a motor based on a detection signal output from the first detection sensor and the second detection sensor, the control device comprising the first detection sensor and the second detection sensor. 4. The tightening according to claim 2, wherein the rotation of the motor is stopped when the load shaft rotates by a predetermined angle from the timing when it is determined that the screws are seated based on the detection signal output from the detection sensor of FIG. Attached tool.