JP2009269137A - Oil pulse tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oil pulse tool formed compact in the longitudinal direction by improving the installation of the rotating position detection sensors and a torque detection sensor. <P>SOLUTION: This oil pulse tool 1 includes a motor 3, an oil pulse unit 4 driven by the motor 3, and an output shaft 5 which is connected to the main shaft 24 of the oil pulse unit 4 and to which an end tool is attached. The oil pulse tool includes the rotating position detection sensors 13a, 13b for detecting the rotating position of the output shaft 5 and the torque detection sensor 12 for detecting the occurrence of an impact torque. The rotating position detection sensors and the torque detection sensor are installed on the output shaft 5 at the generally same position in the axial direction. The torque detection sensor is installed on the inner peripheral side, and the rotating position detection sensors are installed on the outer peripheral side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an oil pulse tool that is rotationally driven by a motor and tightens a fastening member such as a bolt using an intermittent impact force generated by hydraulic pressure.

  As an impact tool for tightening screws, bolts, etc., an oil pulse tool that generates a striking force using hydraulic pressure is known. The oil pulse tool has a feature that operation noise is low because there is no collision between metals. As such an oil pulse tool, for example, there is Patent Document 1, an air motor is used as power for driving the oil pulse unit, and an output shaft of the air motor is directly connected to the oil pulse unit. When a trigger switch for operating the oil pulse tool is pulled, high-pressure air is supplied to the air motor.

Japanese Patent Laid-Open No. 2007-30056

  A conventional oil pulse tool is provided with a rotation position detection sensor that detects the rotation angle of the output shaft to which the tip tool is attached, and a torque detection sensor that detects the generation of torque at the time of impact. However, since these two sensors are provided at different positions in the axial direction of the output shaft, the length of the output shaft portion of the oil pulse tool is required to some extent, and the total length of the oil pulse tool is increased. there were.

  The present invention has been made in view of the above background, and an object of the present invention is to provide an oil pulse tool having a compact overall length by devising attachment of a rotational position detection sensor and a torque detection sensor.

  Another object of the present invention is to provide an oil pulse tool capable of improving the detection accuracy of both sensors by devising the mounting of a rotational position detection sensor and a torque detection sensor in the oil pulse tool.

  Of the inventions disclosed in the present application, typical features will be described as follows.

According to one aspect of the present invention, in an oil pulse tool having a motor, an oil pulse unit driven by the motor, and an output shaft connected to the shaft of the oil pulse unit and mounted with a tip tool, the rotation of the output shaft A rotational position detection sensor for detecting the position and a torque detection sensor for detecting the occurrence of impact torque are provided, and the rotational position detection sensor and the torque detection sensor are arranged so as to overlap in the axial direction of the output shaft.

  The term “overlapping” as used herein means that the axial lengths of both may be completely coincided with each other as well as a part of the axial lengths of both. As this structure, the strain gauge is preferably provided on the inner peripheral side, and the rotational position detection sensor is preferably provided on the outer peripheral side. Further, in the axial direction of the output shaft, the input / output transformer coil of the torque detection sensor is provided at a position adjacent to the rotational position detection sensor and the torque detection sensor.

  According to another feature of the present invention, the output shaft is rotatably fixed by the bearing, and the rotational position detection sensor is fixed not to the output shaft but to the bearing.

  According to still another feature of the present invention, the rotational position detection sensor is constituted by a rotor and a hall element, and the rotor is fixed to a rotating portion of the bearing.

  According to still another feature of the present invention, the output shaft has a reduced diameter of the rotational position detection sensor portion in the axial direction, and the strain gauge is fixed to a portion having a small diameter. The narrow-diameter portion has a substantially square cross section, and a strain gauge is attached to each plane located on the outer periphery of the cross section.

  According to the first aspect of the present invention, since the rotational position detection sensor and the torque detection sensor are arranged so as to overlap in the axial direction of the output shaft, the total length of the output shaft can be shortened and the total length (front-rear length) is short. An oil pulse tool can be realized.

  According to the invention of claim 2, since the rotational position detection sensor is provided on the inner peripheral side and the rotational position detection sensor is provided on the outer peripheral side, an oil pulse tool with good space efficiency and a short overall length (front and rear length) can be realized. . Further, since the rotational position detection sensor is arranged on the outer peripheral side, the diameter of the rotor of the rotational position detection sensor is increased, and the position detection accuracy is improved.

  According to the invention of claim 3, since the output shaft is rotatably fixed by the bearing and the rotational position detection sensor is fixed to the bearing, the rotational position detection sensor can be manufactured integrally with the bearing and can be easily assembled. A tool can be realized.

  According to the fourth aspect of the present invention, the rotational position detection sensor is composed of a rotor and a Hall element, and the rotor is fixed to the rotating part of the bearing, so that the rotating part of the bearing can have a role of holding the rotor. it can. As a result, the number of parts can be reduced.

  According to the invention of claim 5, since the diameter of the rotational position detection sensor portion is thin in the axial direction of the output shaft, and the strain gauge as the torque detection sensor is fixed to the thin portion, the use of space In addition to improved efficiency, the detection accuracy of the torque detection sensor can be improved.

  According to the sixth aspect of the present invention, the narrow-diameter portion has a substantially square cross section, and the strain gauges are attached to the planes positioned on the outer periphery of the cross section, so that the detection accuracy of the torque detection sensor can be further improved. .

  According to the seventh aspect of the present invention, the input / output transformer coil of the torque detection sensor is provided at a position adjacent to the rotational position detection sensor and the torque detection sensor in the axial direction of the output shaft. The wiring to the transformer coil can be made short, and a torque detection sensor that is easily affected by noise and has high detection accuracy can be realized.

  The above and other objects and novel features of the present invention will become apparent from the following description and drawings.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the present specification, the vertical and forward / backward directions will be described as the directions shown in FIG. FIG. 1 is a cross-sectional view showing an entire oil pulse tool according to an embodiment of the present invention.

  The oil pulse tool 1 drives a motor 3 using electric power supplied from the outside by a power cord 2, drives an oil pulse unit 4 by the motor 3, and rotates on an output shaft 5 connected to the oil pulse unit 4. By applying force and striking force, rotation striking force is transmitted continuously or intermittently to a tip tool (not shown) such as a hexagon socket to perform operations such as nut tightening and bolt tightening.

  The power supplied by the power cord 2 is direct current or alternating current such as AC 100V. In the case of alternating current, a rectifier (not shown) is provided in the oil pulse tool 1 and converted to direct current, and then sent to the motor drive circuit. The motor 3 is a brushless DC motor having a rotor 3b having a permanent magnet on the inner peripheral side and a stator 3a having a winding wound around an iron core on the outer peripheral side. The motor 3 includes two bearings 10a and 10b. The rotating shaft is fixed and accommodated in the cylindrical body portion 6a of the housing. In the housing, the body portion 6a and the handle portion 6b are integrally made of plastic or the like. A drive circuit board 7 for driving the motor 3 is disposed behind the motor 3, and an inverter circuit composed of a semiconductor element such as an FET and the rotational position of the rotor 3b are detected on the circuit board. Therefore, a rotational position detecting element 42 such as a Hall element or Hall IC is mounted. A cooling fan unit 17 for cooling is provided at the rearmost end inside the body portion 6a of the housing.

  A trigger switch 8 is disposed in the vicinity of the attachment portion of the handle portion 6b of the housing extending downward from the body portion 6a at a substantially right angle, and is proportional to the amount of the trigger switch 8 pulled by the switch circuit board 14 provided immediately below. The signal is transmitted to the motor control board 9a. Below the handle portion 6b, there are provided three control boards 9, a motor control board 9a, a torque detection board 9b, and a rotational position detection board 9c. A plurality of light emitting diodes (LEDs) 18 are provided on the rotational position detecting substrate 9c, and the light from the light emitting diodes 18 is disposed so that it can be identified from the outside through a transmission window of a housing (not shown) or through a through hole. .

  In the oil pulse unit 4 built in the body portion 6 a of the housing, the rear liner plate 23 is directly connected to the rotating shaft of the motor 3, and the front main shaft 24 is directly connected to the output shaft 5. When the trigger switch 8 is pulled to start the motor 3, the rotational force of the motor 3 is transmitted to the oil pulse unit 4. When the oil pulse unit 4 is filled with oil and no load is applied to the output shaft 5 or when the load is small, the output shaft 5 is nearly rotated by the motor 3 only by the resistance of the oil. Rotate synchronously. When a strong load is applied to the output shaft 5, the rotation of the output shaft 5 and the main shaft 24 stops, and only the liner on the outer peripheral side of the oil pulse unit 4 continues to rotate. The pressure rapidly rises to generate an impact pulse, and the main shaft 24 is rotated by a strong spire-like torque, and a large tightening torque is transmitted to the output shaft 5. Thereafter, the same striking operation is repeated several times, and the fastening target is tightened with the set torque.

  The output shaft 5 is held at the rear end by a bearing 10 c and at the front by a metal bearing 16 in a case 15. The bearing 10c of the present embodiment is a ball bearing, but other bearings such as a needle bearing can be used. A rotational position detection sensor 13 is attached to the bearing 10c. The rotation position detection sensor 13 includes a permanent magnet 13a fixed to the inner ring of the ball bearing 10c and rotating in synchronization with the output shaft 5, a sensor housing fixed to the outer ring and covering the ball bearing, and a position detection element 13b such as a Hall IC. Consists of including. The permanent magnet 13a has a plurality of magnetic pole sets, and a connector 13c for transmitting the signal of the position detection element 13b to the outside is provided at one place on the outer peripheral side of the cover facing the permanent magnet 13a.

  On the inner peripheral side of the permanent magnet 13a, the diameter of the output shaft 5 is thin, and a strain gauge 12 as a torque detection sensor is attached to the thinned portion. On the front side of the location where the strain gauge 12 is attached, the diameter of the output shaft 15 is thick, and an input transformer set 11a for supplying a voltage to the strain gauge 12 at that location and the output from the strain gauge 12 are transmitted. An output transformer set 11b is provided. The input transformer set 11a and the output transformer set 11b include coils disposed on the inner peripheral side and the outer peripheral side, respectively. The inner peripheral side coil is fixed to the output shaft 5, and the outer peripheral side coil is fixed to the case 15. Input / output voltages to the input transformer set 11a and the output transformer set 11b are transmitted to the torque detection board 9b via the connector 11c. Each part mentioned above attached to the output shaft 5 is integrated in the cylindrical case 15, and the case 15 is attached to the trunk | drum 6a of a housing. In addition, a wiring cover 31 for covering connection wiring and the like is provided at the lower portion of the case 15.

  FIG. 2 is an enlarged cross-sectional view of the oil pulse unit 4 of FIG. The oil pulse unit 4 is mainly composed of two parts: a drive part that rotates in synchronization with the motor 3 and an output part that rotates in synchronization with the output shaft 5 to which the tip tool is attached. The drive portion that rotates in synchronization with the motor 3 includes a liner plate 23 that is directly connected to the rotation shaft of the motor 3, and an integrally formed liner 21 having an outer diameter that is fixed so as to extend forward on the outer peripheral side thereof. including. The output portion that rotates in synchronization with the output shaft 5 includes a main shaft 24 and blades 25a and 25b that are attached to grooves formed 180 degrees apart on the outer peripheral side of the main shaft 24 via springs. .

  The main shaft 24 is passed through an integrally molded liner 21 and is held so as to be able to rotate in a closed space formed by the liner 21 and the liner plate 23. Oil for generating torque is generated in the closed space. (Hydraulic oil) is filled. An O-ring 30 is provided between the liner 21 and the main shaft 24, and an O-ring 29 is provided between the liner 21 and the liner plate 23 to ensure airtightness between them. Although not shown, the liner 21 is provided with a relief valve for releasing the oil pressure from the high pressure chamber to the low pressure chamber, and the tightening torque can be adjusted by controlling the maximum oil pressure generated.

  FIG. 3 is a cross-sectional view taken along the line BB of FIG. Inside the liner 21 is formed a liner chamber having a cross section that forms four regions as shown in FIG. Blades 25 a and 25 b are fitted and inserted into two opposed groove portions on the outer peripheral portion of the main shaft 24 via springs, and attached to the circumferential direction by the springs so that the blades 25 a and 25 b abut against the inner surface of the liner 21. Be forced. On the outer peripheral surface of the main shaft 24 between the blades 25a and 25b, two convex seal surfaces 26a and 26b that are axially extending are provided. Convex seal surfaces 27a and 27b and convex portions 28a and 28b are formed on the inner peripheral surface of the liner 21.

  When the seating surface of the tightening bolt is seated when the oil pulse tool 1 is tightened, a load is applied to the main shaft 24, the main shaft 24 and the blades 25a and 25b are almost stopped, and only the liner 21 continues to rotate. As the liner 21 rotates with respect to the main shaft 24, an impact pulse is generated once per rotation. The oil pulse tool 1 is formed on the inner peripheral surface of the liner 21 when the impact pulse is generated. The convex seal surface 27a and the convex seal surface 26a formed on the outer peripheral surface of the main shaft 24 are in contact with each other. At the same time, the convex seal surface 27b and the convex seal surface 26b come into contact with each other. As described above, the pair of convex seal surfaces formed on the inner peripheral surface of the liner 21 and the pair of convex seal surfaces formed on the outer peripheral surface of the main shaft 24 are in contact with each other. It is divided into a chamber and two low-pressure chambers. An instantaneous strong rotational force is generated in the main shaft 24 due to the pressure difference between the high pressure chamber and the low pressure chamber.

  Next, the operation procedure of the oil pulse unit 4 will be described. First, when the trigger 8 is pulled, the motor 3 is rotated, and the liner 21 is rotated in synchronization therewith. In the present embodiment, the liner plate 23 is directly connected to the rotation shaft of the motor 3 and rotates at the same rotation speed. However, the present invention is not limited to this configuration, and may be connected via a speed reduction mechanism.

  (1) to (8) in FIG. 3 are views showing a state in which the liner 21 makes one rotation at a relative angle with respect to the main shaft 24. As described above, when no load is applied to the output shaft 5 or when the load is small, the main shaft 24 rotates almost in synchronization with the rotation of the motor 3 only by the resistance of oil. When a strong load is applied to the output shaft 5, the rotation of the main shaft 24 directly connected thereto stops and only the outer liner 21 continues to rotate.

  (1) in FIG. 3 is a diagram showing a positional relationship when a striking force is generated on the main shaft 24 by an impact pulse. The position shown in (1) is a “position where oil is sealed”, which is located once per rotation. Here, the convex sealing surfaces 27a and 26a, the sealing surface 27b and the sealing surface 26b, the blade 25a and the convex portion 28a, and the blade 25b and the convex portion 28b contact each other in the entire axial direction of the main shaft 24, respectively. As a result, the inner space of the liner 21 is divided into four chambers of two high-pressure chambers and two low-pressure chambers.

  Here, the high pressure and the low pressure are pressures of oil existing inside. Further, when the liner 21 is rotated by the rotation of the motor 3, the volume of the high pressure chamber decreases, so that the oil is compressed and a high pressure is instantaneously generated. This high pressure pushes the blade 5 toward the low pressure chamber. As a result, a powerful rotational torque is generated on the main shaft 24 by momentarily applying a rotational force via the upper and lower blades 5a, 5b. By forming this high-pressure chamber, a strong striking force that rotates the blades 25a, 25b in the clockwise direction in the drawing acts. The position shown in FIG. 3A is referred to as “blow position” in this specification.

  FIG. 3 (2) shows a state in which the liner 21 has rotated 45 degrees from the striking position. After passing the striking position shown in (1), the convex seal surfaces 27a and 26a, the convex seal surface 27b and the seal surface 26b, the blade 25a and the convex portion 28a, and the blade 25b and the convex portion 28b are in contact with each other. Is released, the space partitioned into the four chambers inside the liner 21 is released, and oil flows into each other space, so that no rotational torque is generated, and the liner 21 further rotates as the motor 3 rotates. .

  FIG. 3 (3) shows a state in which the liner 21 has rotated 90 degrees from the striking position. In this state, the blades 25a and 25b contact the convex seal surfaces 27a and 27b and retreat radially inward to a position where they do not protrude from the main shaft 24. Therefore, no rotational torque is generated without being affected by the oil pressure. The liner 21 rotates as it is.

  FIG. 3 (4) shows a state in which the liner 21 has rotated 135 degrees from the striking position. In this state, the inner space of the liner 21 communicates and no oil pressure change occurs, so that no rotational torque is generated on the main shaft.

  FIG. 3 (5) shows a state in which the liner 21 has rotated 180 degrees from the striking position. At this position, the convex seal surfaces 27b and 26a and the convex seal surface 27b and the seal surface 26b come close to each other, but do not come into contact with each other. This is because the convex seal surfaces 26a and 26b formed on the main shaft 24 are not in a symmetrical position with respect to the axis of the main shaft. Similarly, the convex sealing surfaces 27a and 27b formed on the inner periphery of the liner 21 are not in a symmetrical position with respect to the axis of the main shaft. Therefore, almost no rotational torque is generated at this position because it is hardly affected by oil. In addition, since the oil with which it is filled is viscous and the convex seal surfaces 27b and 26a or the convex seal surfaces 27a and 26b face each other, a slightly high pressure chamber is formed. ) To (4) and (6) to (8), a slight rotational torque is generated, but this rotational torque has no effect on tightening.

  The states (6) to (8) in FIG. 3 are substantially the same as (2) to (4), and no rotational torque is generated in these states. Further rotation from the state of (8) returns to the state of (1) of FIG. 3, the convex sealing surfaces 27a and 26a, the sealing surface 27b and the sealing surface 26b, the blade 25a and the convex portion 28a, the blade 25b. And the convex portion 28b contact each other in the entire axial direction of the main shaft 24, and thereby the inner space of the liner 21 is partitioned into four chambers of two high-pressure chambers and two low-pressure chambers. Torque is generated.

  Next, the mounting structure of the rotational position detection sensor and the torque detection sensor will be described with reference to FIG. FIG. 4 is a cross-sectional view taken along a line AA in FIG. A metal rotation position detection sensor cover 33 b that does not rotate is located inside the case 15. A cylindrical rotor 33a is provided on the inner peripheral side, and a permanent magnet 13a having a magnetic pole disposed in the circumferential direction is fixed to the outer periphery of the rotor 33a. The rotor 33a is fixed to the inner ring of the bearing 10c and rotates together with the inner ring. A position detection element 13b such as a Hall element is provided at one or a plurality of positions on the outer peripheral side of the permanent magnet 13a, and thereby the rotational position of the output shaft 5 can be accurately detected. The connector 34 is a connector for connecting the output of the position detection element 13b to the outside, and a connection line for connection from the position detection element 13b to the connector 34 is provided through a path not depicted in the sectional view. . The wiring cover 31 is a cover for forming a space through which the wiring for detecting the rotational position and the wiring for the torque detection sensor pass.

  The output shaft 5 is located in the space on the inner peripheral side of the rotor 33a. Here, as can be understood from FIG. 4, in the cylindrical output shaft 5, only the position where the strain gauge 12 is attached has a small diameter and a substantially square cross section. And the strain gauge 12 was provided in each of the four planes located in the outer periphery of a cross section. Thereby, the detection accuracy of torque can be improved.

  As described above, in this embodiment, since the rotational position detection sensor and the torque detection sensor are arranged at the same position in the axial direction of the output shaft or overlapped, the total length of the output shaft can be shortened. It is possible to realize an oil pulse tool with a short overall length (front / rear length). Further, since the rotational position detection sensor is arranged on the outer peripheral side, the diameter of the rotor of the rotational position detection sensor is increased, and the position detection accuracy is improved. In addition, since the output shaft is rotatably fixed by the bearing and the rotational position detection sensor is fixed to the bearing, the rotational position detection sensor can be manufactured integrally with the bearing, and an oil pulse tool that can be easily assembled can be realized. Further, the rotational position detection sensor is composed of a rotor and a hall element, and the rotor is fixed to the rotating part of the bearing, so that the role of holding the rotor can be given to the rotating part of the bearing, and the number of parts can be reduced. realizable.

  Next, the configuration and operation of the drive control system of the motor 3 will be described with reference to FIG. FIG. 5 is a block diagram showing the configuration of the drive control system of the motor 3. In the present embodiment, the motor 3 is a three-phase brushless DC motor. This brushless DC motor is an inner rotor type, and includes a rotor (rotor) 3b including a plurality of sets of permanent magnets (magnets) including N poles and S poles, and a star-connected three-phase fixing. In order to detect the rotational position of the stator 3a (stator) composed of the child windings U, V, and W and the rotational position of the rotor 3b, three rotational positions are arranged at predetermined intervals in the circumferential direction, for example, every 30 °. A detection element 42 is provided. Based on the position detection signals from these rotational position detection elements 42, the energization direction and time to the stator windings U, V, W are controlled, and the motor 3 rotates.

  The drive circuit 47 includes six switching elements Q1 to Q6 such as FETs connected in a three-phase bridge format. The gates of the six switching elements Q1 to Q6 connected in a bridge are connected to the control signal output circuit 46, and the drains or sources of the six switching elements Q1 to Q6 are star-connected stator windings. Connected to U, V, W. Thus, the six switching elements Q1 to Q6 perform a switching operation by the switching element drive signals (drive signals H1 to H6) input from the control signal output circuit 46, and are applied to the drive circuit 47. Is supplied to the stator windings U, V, and W as three-phase (U-phase, V-phase, and W-phase) voltages Vu, Vv, and Vw. Note that the DC power source 52 may be constituted by a secondary battery that is detachably provided.

  Of the switching element drive signals (three-phase signals) for driving the gates of the six switching elements Q1 to Q6, the three negative power supply side switching elements Q4, Q5, Q6 are converted into pulse width modulation signals (PWM signals) H4, The operation amount (stroke) of the trigger switch 8 is supplied to the motor 3 by changing the pulse width (duty ratio) of the PWM signal based on the detection signal of the applied voltage setting circuit 49. Is adjusted to control the start / stop and rotation speed of the motor 3.

  Here, the PWM signal is supplied to one of the positive power supply side switching elements Q1 to Q3 or the negative power supply side switching elements Q4 to Q6 of the drive circuit 47, and the switching elements Q1 to Q3 or the switching elements Q4 to Q6 are switched at high speed. As a result, the power supplied to each stator winding U, V, W from the DC power source is controlled. In this embodiment, since the PWM signal is supplied to the negative power supply side switching elements Q4 to Q6, the electric power supplied to the stator windings U, V, W by controlling the pulse width of the PWM signal. Can be adjusted to control the rotation speed of the motor 3.

  The oil pulse tool 1 is provided with a forward / reverse switching lever 51 for switching the rotational direction of the motor 3, and the rotational direction setting circuit 50 switches the rotational direction of the motor each time a change in the forward / reverse switching lever 51 is detected. Then, the control signal is transmitted to the calculation unit 41.

  Although not shown, the calculation unit 41 is a central processing unit (CPU) for outputting a drive signal based on the processing program and data, a ROM for storing the processing program and control data, and for temporarily storing data. RAM, a timer, and the like.

  The rotation angle detection circuit 44 is a circuit that receives a signal from the position detection element 13 b of the rotation position detection sensor 13 and detects the rotation position (rotation angle) of the output shaft 5, and outputs the detected value to the calculation unit 41. To do. The hit detection circuit 45 is a circuit that detects the timing of hitting by detecting the generation of torque using the signal of the strain gauge 12 as an input.

  The control signal output circuit 46 forms a drive signal for alternately switching predetermined switching elements Q1 to Q6 based on the output signals of the rotation direction setting circuit 50 and the rotor position detection circuit 43, and controls the drive signal. The signal is output to the signal output circuit 46. As a result, the predetermined windings of the stator windings U, V, and W are alternately energized to rotate the rotor 3b in the set rotation direction. In this case, the drive signal applied to the negative power supply side switching elements Q4 to Q6 of the drive circuit 47 is output as a PWM modulation signal based on the output control signal of the applied voltage setting circuit 49. The current value supplied to the motor 3 is measured by the current detection circuit 49, and the value is fed back to the calculation unit 41 so as to be adjusted to the set driving power. The PWM signal may be applied to the positive power supply side switching elements Q1 to Q3.

  Next, control for changing the power supplied to the motor 3 in conjunction with the impact of the oil pulse unit 4 will be described with reference to FIGS.

  FIG. 6 (1) is a diagram showing the relationship between the tightening torque and time until the oil pulse unit 4 is hit and tightened to the set torque in the prior art. At the time of bolt tightening, the oil pulse tool 1 rotates in synchronization with the liner 21 and the main shaft 24 until the seating surface of the tightening bolt is seated. However, when a load is applied to the main shaft 24, the main shaft 24 is almost stopped. Thus, only the liner 21 continues to rotate. Then, intermittent tightening torque is transmitted to the output shaft 5 by the action of the oil pulse unit. FIG. 6 (1) shows this state. The vertical axis is the magnitude of the tightening torque, and the horizontal axis is the time. The numbers above the spire-like torque curve generated intermittently are the number of pulses (hitting). Here, small pulses 61 to 67 are generated on the right side of the large spire-shaped pulse. The generation principle of the pulses 61 to 67 will be further described with reference to FIG.

  FIG. 6 (2) is a diagram showing the rotation state of the liner 21 with respect to the output shaft 5 at the time of hitting. For example, the situation of the seventh to eighth hits 68 in FIG. 6 (1) is shown. . In FIG. 6 (2), when the motor 3 makes one rotation under normal rotation control (path indicated by circle 1 in the figure) and reaches the fifth impact position, the liner 21 and the motor 3 are caused by the reaction force received from the output shaft 5. Is reversed by a certain distance (route indicated by circle 3 in the figure). This distance is not constant depending on the magnitude of the reaction force, the viscosity of the oil filled in the oil pulse unit 4, and the like, but when it is large, the rotation angle may return about 60 degrees. Usually, only one impact is not sufficient to fasten the fastening member, so the motor 3 must be rotated forward again. For this reason, predetermined driving power is supplied to the motor 3, but if the driving power for normal rotation is supplied when the motor 3 is rotating in reverse (the path indicated by circle 3 in the figure), a large amount of current flows to generate heat. Inefficient and wasteful of electricity. Therefore, in this embodiment, the driving power in the path of the circle 3 is reduced as compared with the normal time.

  Further, when the motor 4 starts to rotate forward (the path indicated by circle 4 in the figure), if the motor 3 is accelerated vigorously, there is little when it reaches the striking position (position between the circle 4 and circle 5 in the figure). A pulse 64 is generated while torque is applied. However, as can be understood from FIG. 6 (1), this torque is much smaller than the torque striking force performed by regular striking, and therefore has no effect on fastening of the fastening member. Therefore, it is preferable to rotate the motor 3 slowly so that no pulse is generated at the striking position between the circle 4 and the circle 5 in (2). In general, the torque generated when the oil pulse unit 4 passes the striking position has a property that it is large at high speed and small at low speed due to the viscosity of the oil. Therefore, in the present invention, the motor 3 is controlled so that the acceleration of the motor 3 is slowed down and rotated at a low speed until a pulse position between the circle 4 and the circle 5 in FIG. To do. Therefore, in the acceleration of the circle 4 in the figure, the driving power supplied to the motor 3 is reduced. After passing the striking position, the acceleration of the motor 3 is returned to the normal control again and repeated until the fastening member is fastened with a predetermined torque.

  Note that the power control described above may be made finer, and control may be performed so as to reduce the influence received by the motor 3 at the moment of striking by reducing the power supply in the section of the circle 2 immediately before the striking position. Further, in the section of the circle 5 immediately after passing the striking position again, the motor 3 may not be suddenly accelerated, but may be accelerated after the influence of the oil viscosity near the striking position is eliminated.

  FIG. 7 is a diagram showing an example of the effective value of the electric power supplied to the motor 3 at the rotational position shown in FIG. The electric power supplied to the motor 3 during the normal rotation in the section 1 of the circle 1 is supplied when the electric power is reduced to about 75% immediately before the hit position of the circle 2 and the motor 3 is reversed in the section 3 of the circle 3 When the motor 3 stops rotating and the motor 3 stops rotating, the power to be supplied is further reduced to accelerate the motor 3 slowly (section 4). After passing the striking position and passing the section of circle 5, the electric power supplied during normal rotation is restored (section of circle 1). In this figure, it is expressed as an effective value of electric power. For example, the control by the PWM (Pulse Width Modulation) method is used, and the ratio (duty ratio) between the time when the switch of the DC power supply is ON and the time when it is OFF. The ratio) may be lowered at the positions of the circle 3 and the circle 4 compared to the position of the circle 1. Further, at the positions of the circles 2 and 5, the duty ratio may be controlled to be lower than that of the circle 1 position. Furthermore, as a power control method, the supplied voltage may be controlled to be low by a PAM method (Pulse Amplitude Modulation) that changes the voltage itself.

  Next, the control procedure of the motor 3 according to the embodiment of the present invention will be described using the flowchart of FIG. In the present embodiment, it is assumed that the motor 3 rotates at a PWM duty of 100% in a section between circle 1 and circle 2 in FIG. 6B (step 81). This state changes depending on the amount by which the trigger switch 8 is pulled. In the present embodiment, for simplicity of explanation, the amount pulled by the trigger switch 8 is assumed to be 100%, and this rotation state is “normal rotation”. That's it. Next, the motor 3 rotates to detect whether the liner 21 has reached the striking position shown in FIG. 6B and whether the motor 3 has been reversed by the striking (step 82). The inversion of the motor 3 can be detected by using a rotational position detecting element 42 attached to the drive circuit board 7 of the motor 3. If the motor is not reversed, the process returns to step 81. If the motor is reversed, the process proceeds to step 83.

  In step 83, the PWM duty ratio of the drive power to the motor 3 is reduced to 50%. The reason why the power is reduced in this way is that if the PWM duty ratio is kept at 100% in the circled section 3 in FIG. 6, the efficiency is poor. Further, if the PWM duty ratio is set to 0%, the reverse rotation brake of the motor 3 is not applied, so that a certain amount of drive power is required.

  Next, it is detected whether the reversal of the motor 3 is stopped (step 84). Whether or not the motor has stopped can be detected by the output of a rotational position detecting element 42 such as a Hall IC attached to the drive circuit board 7 of the motor 3. When the reversal of the motor 3 is stopped, the control is shifted to the normal rotation of the motor 3 (step 85). At this time, the PWM duty ratio is suppressed to about 25% until passing through the section 4 shown in FIG. 6 so that no pulse is generated when passing the striking position (step 86). When the passage of the hit occurrence position is detected in step 87, the limitation on the drive power of the motor 3 is released, the PWM duty ratio is set to 100%, and the motor 3 is driven so as to reach the next hit position as fast as possible.

  According to the control in the embodiment described above, the electric power supplied to the electric motor is reduced immediately before or when the impact force is transmitted to the output shaft, and the electric motor whose rotation is disturbed by the pulsed torque is After passing the striking position, the electric power is returned to the normal electric power, so that it is possible to reduce the electric power consumed when the rotation of the motor is disturbed during the generation of the pulsed torque, and to prevent the generation of heat due to the electric power. .

  Next, a second modification of the control procedure of the motor 3 according to the embodiment of the present invention will be described using the flowchart of FIG. It is assumed that the motor 3 normally rotates at a PWM duty of 100% in a section between circle 1 and circle 2 in FIG. 6B (step 91). Next, the motor 3 rotates and the liner 21 reaches the strike position shown in FIG. 6 (2), and it is detected whether or not the rotation of the motor 3 is stopped, that is, locked by the strike (step 92). Whether or not the motor 3 is locked can be detected by using a rotational position detecting element 42 attached to the drive circuit board 7 of the motor 3. Here, being locked indicates that there are almost no paths of circles 3 and 4 in FIG. 6B. If the motor is not locked in step 92, the process returns to step 91. If it is locked, the process proceeds to step 93.

  In step 93, the PWM duty ratio of the drive power to the motor 3 is reduced to 50%. The reason why the power is reduced in this way is that a large amount of current flows when 100% driving power is applied to the locked motor 3. Further, since the position after locking is in the vicinity of the hitting position, it is better not to make it 100% until it passes the hitting position.

  Next, it is detected whether or not the liner 21 has passed the impact occurrence position (step 94). If it has not passed, step 94 is repeated, and if it has passed, the process proceeds to step 95, where the PWM duty ratio is suppressed to about 25% so that no pulse is generated when passing the striking position (step 95). . Then, it is determined whether or not it has been rotated by a predetermined angle indicated by a circle 5 in FIG. 6 (2) (step 96), and when it is detected that the rotation has been performed, the restriction on the driving power of the motor 3 is released, and the PWM duty ratio is set. Drive at 100% (step 97). Whether or not the rotation has been made by a predetermined angle can be identified by using the output of the rotational position detection element 42 and the output of the rotational position detection sensor 13.

  According to the control of the second modification described above, the motor can be smoothly rotated because the electric power is returned to the normal power after passing through the impact position and having no influence.

  Next, a third modification of the control procedure of the motor 3 according to the embodiment of the present invention will be described using the flowchart of FIG. The motor 3 is assumed to normally rotate at a PWM duty of 100% in the section between circle 1 and circle 2 in FIG. 6B (step 101). Next, the motor 3 rotates to detect whether or not the liner 21 has reached the strike position shown in FIG. 6 (2) and has been hit (step 102). Whether or not hitting has been performed can be detected using the output of the torque detection sensor (strain gauge 12). If no hit is detected in step 102, the process returns to step 101. If detected, the process proceeds to step 103. In step 103, the PWM duty ratio of the drive power to the motor 3 is reduced to 50%. Next, in step 104, it is detected whether or not a predetermined time has passed, and when the passage is detected, the restriction on the driving power of the motor 3 is released and the PWM duty ratio is driven at 100% (step 105). Whether or not a certain time has passed since the impact has occurred can be detected by a microcomputer built in the calculation unit 41 using a timer. Therefore, the third modification can be applied to a drive source that does not have the rotational position detection element 42, for example, a DC motor, provided with a torque detection sensor.

  Next, a fourth modification of the control procedure of the motor 3 according to the embodiment of the present invention will be described using the flowchart of FIG. It is assumed that the motor 3 normally rotates at a PWM duty of 100% in the section between circle 1 and circle 2 in FIG. 6B (step 111). Next, it is detected whether the motor 3 has rotated and the liner 21 has reached the striking position shown in FIG. 6B (step 112). Here, the meaning of “arrival” not only means completely matching the hitting position, but also means a predetermined range before and after the hitting position, and particularly preferably the range of circle 2 in FIG. In order to determine whether or not the hit position has been reached, the previous hit position is stored in the calculation unit 41.

  If the hit position has not been reached, the process returns to step 111, and if reached, the process proceeds to step 113. In step 113, the PWM duty ratio of the driving power to the motor 3 is reduced to 50%. Next, it is detected whether or not an impact has been made (step 114). Whether or not hitting has been performed can be detected using the output of the torque detection sensor (strain gauge 12). When the hit is made, the rotation angle of the motor 3 at the time of hit is stored in the calculation unit (step 115). Further, not only the rotation angle of the motor 3 but also the rotation position of the output shaft 5 may be stored together.

  Next, after the motor 3 reverses or stops, it rotates forward to detect whether it has passed the impact occurrence position (step 116), and when it passes, the PWM duty ratio of the drive power to the motor 3 is reduced to 25% ( Step 117). Next, it is detected in step 118 whether or not the motor has been rotated by a predetermined angle. If the motor has rotated, the restriction on the driving power of the motor 3 is released and the PWM duty ratio is driven at 100% (step 119). Accordingly, in the fourth modification, the power supplied to the motor is reduced immediately before the pulse position generated in the oil pulse unit, so that adverse effects due to the driving power flowing in the motor when an impact force is generated are reduced. be able to. In addition, a torque detection sensor that detects the occurrence of impact force is provided, and the power supplied to the motor is adjusted based on the output of the torque detection sensor, so the timing for reducing the drive power of the motor can be detected in a simple manner. can do.

  Next, a fifth modification of the control procedure of the motor 3 according to the embodiment of the present invention will be described using the flowchart of FIG. The motor 3 is assumed to normally rotate at a PWM duty of 100% in the section between circle 1 and circle 2 in FIG. 6B (step 121). Next, it is detected whether the motor 3 has rotated and the liner 21 has reached the previous striking position (step 122). Whether or not the previous hit position has been reached is determined based on the position stored in the calculation unit 41. If the hit position has not been reached, the process returns to step 121, and if reached, the process proceeds to step 123. In step 123, the PWM duty ratio of the drive power to the motor 3 is reduced to 75%. Next, in step 124, it is detected whether or not the motor 3 is reversed by the impact. If the motor has been reversed, the PWM duty ratio of the drive power to the motor 3 is reduced to 50%, and the rotation angle of the motor 3 at the time of reversal is stored in the computing unit 41 (steps 125 and 126).

  Next, it is detected whether the reversal of the motor 3 is stopped (step 127). If the stop of the motor 3 can be detected, control for rotating the motor in the forward direction is started (steps 127 and 128). At this time, the PWM duty ratio is suppressed to about 25% so that no pulse is generated when passing the striking position (step 129). When the passage of the hit occurrence position is detected in step 130, the restriction on the drive power of the motor 3 is released, the PWM duty ratio is driven at 100%, and the motor 3 is driven so as to reach the next hit position as fast as possible. (Step 131).

  As described above, according to the present embodiment, since the drive current is limited when the motor is reversed or stopped after being hit, unnecessary power is not consumed. Consumption efficiency can be improved and generation of heat can also be prevented. Furthermore, according to the present embodiment, when passing through the striking position again, since it is passed at a low speed, no pulse is generated, so that useless striking can be prevented and smooth tightening work can be performed.

  Next, a method for detecting the performance deterioration of the oil pulse unit 4 will be described with reference to FIGS. In the present embodiment, the focus is mainly on the performance degradation of the oil pulse unit 4 due to oil leakage, and an alarm is generated for the operator before the oil leakage becomes serious.

  FIG. 13 shows the striking position indicated by 68 in FIG. 6 (1), that is, the position showing the torque peak value. It is a figure which shows the time until it passes through a certain position and reaches | attains a striking position again. (1) is a diagram showing the relationship between torque generated by a new oil pulse unit 4 and time. Due to the viscosity of the oil, the torque when passing through the impact position of the oil pulse unit 4 has the property of being high at high speed and low at low speed. As shown in FIG. 13 (1), after the large torque is generated once at the positions where the convex seal surfaces 27a and 26a and 27b and 26b face each other (the seventh hit), the liner 21 is subjected to a reaction. It takes the time of T1 to reversely rotate, to start normal rotation again by the rotational force of the motor 3, and to pass through the striking position again. A slight torque is generated at a position rotated 180 degrees from the striking position, but it is not shown here. Then, the next hitting position (eighth hit) is reached, and tightening torque is generated.

  On the other hand, FIG. 13B is data showing the relationship between the torque generated by the oil pulse unit 4 whose performance has deteriorated due to oil leakage or the like and the time. From the generation of the tightening torque at the striking position (seventh striking), it takes time T2 for the motor 3 to start rotating in reverse and then to pass through the striking position again to generate a small torque. As can be understood by comparing FIGS. 13 (1) and (2), the oil pulse unit 4 in which oil leakage has occurred due to long-term use, life, etc. has a shorter passage time T until a small torque is generated. , T1> T2. A decrease in performance can be detected from the amount of time reduction.

  In addition, by continuously using the oil pulse tool 1, the temperature of the oil in the oil pulse unit 4 rises, and the passage time T also changes due to the temperature rise. In this case, the original value is restored when the oil is cooled. Therefore, it is possible to detect an oil leak by detecting a change with passage of time T during cooling or at the same temperature. Further, the passage time T varies depending on the rotation speed of the motor 3. Therefore, when detecting the passage time T, it is preferable to always monitor the passage time T under the same conditions.

  When oil leakage of the oil pulse unit 4 occurs, the resistance due to the oil in the liner 21 decreases. As a result, the motor 3 starts rotating in the reverse direction from the striking position and then starts to rotate forward, and again passes through the striking position (2 ), Only T2 time is required. Therefore, the occurrence of oil leakage can be predicted or detected in advance by monitoring how this time changes with time.

  FIG. 14 is a flowchart illustrating a procedure for detecting oil leakage using the passage time T. In FIG. 14, a tightening operation is performed by applying a tightening torque as shown in FIG. 13 (1) (step 141). The number of fastenings at this time is recorded in the memory device of the calculation unit 41. The total number may be recorded, or data for every predetermined number may be recorded, for example, every 100 or every 500. Further, not only the number information such as the 100th and 500th information but also the date / time information corresponding to the number information may be recorded.

  Next, the passage time T between the first torque and the second torque when reaching the set torque at the time of tightening is acquired (step 143). In FIG. 6 (1), since the set torque has been reached at the seventh hit, the passing time T at the seventh hit is recorded, so the time interval T2 at this time is recorded (step 144). . Next, the reference values T1 and T2 recorded in advance in the calculation unit 41 are calculated (step 145). Here, for example, T1−T2, but the present invention is not limited to this, and an operation such as T1 / T2 may be performed.

  In step 146, if T1-T2 <reference value 1, there is a high possibility that oil leakage will occur, so a deterioration prior notice is made (step 147). This notification may be displayed on another display unit by turning on the light-emitting diode 18, sounding a buzzer, or the like. Next, in step 148, if T1−T2 <reference value 2, then it is no longer suitable for continuous use. Therefore, an instruction to replace the oil pulse unit 4 is given by notification to that effect, or oil is used as necessary. The operation is stopped so that the pulse tool 4 is not operated (step 149). Here, the reference value 2 is shorter than the reference value 1.

  As described above, according to the present embodiment, an alarm is issued in advance before the life of the oil pulse unit 4 reaches the end of its life, so that each part inside the pulse tool 1 can be used continuously without recognizing the end of the life. Can be prevented from being affected by oil leakage. Therefore, the operator can surely know the possibility of performance degradation and oil leakage. Furthermore, since the performance degradation of the oil pulse unit is detected by comparing the measured transit time with the transit time stored in the memory device, each tool is not affected by the individual differences of the tool itself. It is possible to detect performance degradation with high accuracy.

  If the control shown in FIGS. 8 to 12 is executed, the generation of a small torque may be suppressed and the passing time T may not be measured. In this case, the motor 3 is supplied only when the passing time T is measured. It is better to measure without controlling to lower the driving voltage. As another method, when the passage time T decreases, the interval between the seventh and eighth impacts is shortened as a result. Therefore, the performance degradation may be detected by the change in the interval between the impacts.

  Further, as another method, instead of measuring the passing time T, the reversal angle until the motor stops rotating due to an impact and the motor stops is measured. You may comprise so that a performance fall may be detected.

  As mentioned above, although demonstrated based on embodiment which shows this invention, this invention is not limited to the above-mentioned form, A various change is possible within the range which does not deviate from the meaning. For example, although an example using a brushless DC motor as a drive source of an oil pulse tool has been described, a DC motor using a brush can be similarly applied. The same applies to an air motor as a drive source.

It is sectional drawing which shows the whole impact driver which concerns on embodiment of this invention. It is an expanded sectional view of the oil pulse unit 4 of FIG. FIG. 3 is a cross-sectional view taken along the line B-B in FIG. It is sectional drawing of the AA part of FIG. It is a block diagram which shows the structure of the drive control system of the motor 3 which concerns on embodiment of this invention. (1) is a diagram showing the relationship between the tightening torque and time until the oil pulse unit 4 is struck and tightened to the set torque in the prior art. It is a figure which shows the rotation condition of the liner 21 with respect to the output shaft 5 at the time of being performed. It is a figure which shows an example of the effective value of the electric power supplied to the motor 3 in the rotation position of the liner 21 shown in FIG. It is a flowchart explaining the control procedure of the motor by embodiment of this invention. It is a flowchart which shows the 2nd modification of the control procedure of the motor 3 by embodiment of this invention. It is a flowchart which shows the 3rd modification of the control procedure of the motor 3 by embodiment of this invention. It is a flowchart which shows the 4th modification of the control procedure of the motor 3 by embodiment of this invention. It is a flowchart which shows the 5th modification of the control procedure of the motor 3 by embodiment of this invention. FIG. 7 is a diagram showing the time from the impact position shown in FIG. 6 until the motor 3 reversely rotates, starts normal rotation, passes through the impact position again, and reaches the next impact position. FIG. 2 is a diagram showing the relationship between the torque generated by the pulse unit 4 and time, and (2) is a diagram showing the relationship between the torque generated by the oil pulse unit 4 whose performance has deteriorated due to oil leakage or the like and time. 4 is a flowchart illustrating a procedure for detecting oil leakage of the oil pulse unit 4.

Explanation of symbols

1 Oil Pulse Tool 2 Power Cord 3 Motor 3a Motor Stator 3b Motor Rotor 4 Oil Pulse Unit 5 Output Shaft 6a Housing Body 6b Housing Handle
7 Drive circuit board 8 Trigger switch 9 Control board
9a Motor control board 9b Torque detection board 9c Rotation position detection board 10a, 10b, 10c Bearing
11a Input transformer set 11b Output transformer set 11c Connector
DESCRIPTION OF SYMBOLS 12 Strain gauge 13 Rotation position detection sensor 13a Permanent magnet 13b Position detection element 14 Switch circuit board 15 Case 16 Metal bearing 17 Cooling fan 18 Light emitting diode 21 Liner 23 Liner plate 24 Main shaft
25a, 25b blade
26a, 26b Convex seal surface 27a, 27b Convex seal surface 28a, 28b Convex part 29, 30 O-ring 31 Wiring cover 33a Rotor 33b Rotation position sensor cover 34 Connector 41 Calculation part 42 Rotation position detection element 43 Rotor position Detection circuit
44 Rotation angle detection circuit 45 Impact detection circuit 46 Control signal output circuit 47 Drive circuit 48 Current detection circuit 49 Applied voltage setting circuit 50 Rotation direction setting circuit 51 Forward / reverse switching lever 52 DC power supply

Claims (7)

In an oil pulse tool having a motor, an oil pulse unit driven by the motor, and an output shaft connected to the shaft of the oil pulse unit and mounted with a tip tool,
A rotational position detection sensor for detecting the rotational position of the output shaft and a torque detection sensor for detecting the occurrence of impact torque;
An oil pulse tool, wherein the rotational position detection sensor and the torque detection sensor are arranged so as to overlap in the axial direction of the output shaft.   2. The oil pulse tool according to claim 1, wherein the torque detection sensor is provided on an inner peripheral side, and the rotational position detection sensor is provided on an outer peripheral side.   The oil pulse tool according to claim 2, wherein the output shaft is rotatably fixed by a bearing, and a rotational position detection sensor is provided in the bearing. The rotational position detection sensor is composed of a rotor and a hall element,
The oil pulse tool according to claim 3, wherein the rotor is fixed to a rotating portion of the bearing.   The diameter of the rotational position detection sensor portion in the axial direction of the output shaft is small, and a strain gauge is fixed to the thin portion of the diameter as the torque detection sensor. Oil pulse tool.   6. The oil pulse tool according to claim 5, wherein the narrow-diameter portion has a substantially square cross section, and a strain gauge is attached to each plane located on the outer periphery of the cross section. The oil pulse tool according to claim 2, wherein a coil of an input / output transformer of the strain gauge is provided at a position adjacent to the rotational position detection sensor and the torque detection sensor in the axial direction of the output shaft. .

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