JP2011067910A - Wheel nut tightening tool for automobile tire replacement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tightening tool achieving an adequate tightening torque to wheel nuts during tire replacement operation. <P>SOLUTION: In the tightening tool, a wrench rotary shaft is interlockingly installed consecutively on an output shaft of a driving motor through a strike mechanism, and a nut holding tube is detachably installed consecutively at the distal end of the wrench rotary shaft. The wheel nuts screwed onto wheel bolts for fixing a tire wheel of an automobile to a hub are tightened at a prescribed torque by the nut holding tube. The number of revolutions of the driving motor until the tightening of the wheel nuts is completed within a predetermined period of time is controlled to be classified into a plurality of stages of revolution modes. The classified revolution modes respectively correspond to a plurality of tightening torque modes where a tightening torque previously adequately prescribed according to the type of the automobile is classified into a plurality of stages. Upon termination of the revolution of the driving motor, the adequate tightening torque to the wheel nuts is achieved. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a tightening tool used for tightening a wheel nut during an automobile tire replacement operation.

  2. Description of the Related Art Conventionally, there are tightening tools such as an impact driver or an impact wrench that are used for tightening a wheel nut during an automobile tire replacement operation. The tightening tool has a wrench rotating shaft (anvil) linked to the output shaft of the drive motor via a striking mechanism, a nut gripping cylinder detachably connected to the tip of the wrench rotating shaft, and a tire wheel of an automobile as a hub A wheel nut that is screwed to a wheel bolt to be fixed to the nut is tightened by a nut gripping cylinder (for example, a tightening tool described in Patent Document 1).

JP 2003-251573 A

  However, when performing tire replacement work using the tightening tool, an operator relies on the feeling of the tightening work. For this reason, although the skilled worker can make the fastening time substantially constant, the beginner cannot perform the work with the fastening time constant, and the torque fastening time varies among the workers.

  An object of the present invention is to provide a tightening tool configured to achieve a proper tightening torque to a wheel nut during a tire replacement operation.

  According to the first aspect of the present invention, a wrench rotation shaft is linked to the output shaft of the drive motor via a transmission mechanism, and a nut gripping cylinder is detachably connected to the tip of the wrench rotation shaft. The number of rotations of the drive motor until the completion of tightening of the wheel nut within a predetermined time in a wheel nut tightening tool for replacing an automobile tire configured to tighten the wheel nut with a specified torque by rotating the shaft through the nut gripping cylinder Are controlled by the control circuit unit so as to be classified into a plurality of rotation modes, and the classified rotation modes are a plurality of tightening torque modes in which the tightening torque properly defined in advance according to the vehicle type is classified into several stages. And that the tightening torque to the appropriate wheel nut is achieved by the end of rotation of the drive motor. A tightening tool of the wheel nut for automobile tire replacement and butterflies.

  In the invention according to claim 2, the transmission mechanism unit detects an impact mechanism unit that converts a continuous rotation operation of the drive motor into an impact operation that is an intermittent rotation operation, and detects the impact operation of the impact mechanism unit. The control circuit unit detects the output signal from the impact detection sensor and then detects that a predetermined time has elapsed, thereby detecting the drive motor. The wheel nut tightening tool for replacing a vehicle tire according to claim 1, wherein the tool is controlled to stop.

  The invention according to claim 3 is characterized in that the time from the start of hitting to the end of hitting in each tightening torque mode is the same, and the wheel nut for replacing an automobile tire according to claim 1 or 2 It is a tightening tool.

  (1) In the first aspect of the present invention, a wrench rotating shaft is linked to the output shaft of the drive motor via a transmission mechanism, and a nut gripping cylinder is detachably connected to the tip of the wrench rotating shaft. A drive motor for tightening a wheel nut within a predetermined time in a wheel nut tightening tool for replacing a vehicle tire configured to tighten a wheel nut with a specified torque via a nut gripping cylinder by rotation of a wrench rotating shaft The control circuit unit controls the number of rotations to be classified into a plurality of rotation modes, and the classified rotation modes are a plurality of tightening torques that are classified in advance according to the vehicle type of the vehicle. It is configured to correspond to the attached torque mode, and it is configured so that proper tightening torque to the wheel nut is achieved by the end of rotation of the drive motor. There.

  Thus, by selecting the tightening with the specified torque according to the vehicle type from the rotation modes classified into several stages by the operator, the selected rotation mode is set to the specified torque according to the vehicle type by the end of the rotation of the drive motor. It corresponds to the tightening torque mode that achieves the tightening operation at the same time, so that no variation occurs among workers regardless of who performs the tightening operation, and it is safe even if they are not skilled workers. Tightening work can be performed with confidence, and stable torque management can be performed. Furthermore, only by selecting the rotation mode corresponding to the vehicle type of the tire change, it is possible to deal with the tire change of any vehicle type with one tightening tool.

  In addition, since the wheel nut is automatically stopped before reaching a properly specified tightening torque, it is possible to prevent the wheel bolt from being broken and the wheel nut from being damaged due to excessive tightening.

  (2) In the present invention described in claim 2, the transmission mechanism section converts the continuous rotation operation of the drive motor into an impact operation that is an intermittent rotation operation, and an impact mechanism It is provided with an impact detection sensor that detects an operation and outputs an output signal, and the control circuit unit detects an elapse of a predetermined time after detecting an output signal from the impact detection sensor, The drive motor is controlled to stop.

  In this way, after detecting the output signal from the impact detection sensor, the drive motor is controlled to stop by detecting that a predetermined time has elapsed, so it is just before reaching each specified tightening torque. Can automatically stop and prevent breakage of the wheel bolt due to overtightening.

  (3) In the present invention according to claim 3, since the time from the start of the hit to the end of the hit is always the same regardless of the type of tire and each tightening torque mode, the operator always has a fixed tightening time. Tightening work can be performed and tightening torque can be managed with peace of mind.

It is the perspective view which showed the whole structure of the clamping tool in this embodiment. It is the side view which showed the whole structure where the clamping tool in this embodiment fractured | ruptured partially. It is the perspective view which showed the structure of the operation panel of the clamping tool in this embodiment. It is explanatory drawing which showed the method of the strength switch of the strength switch of the fastening tool in this embodiment. It is the front view which showed the structure of the drive motor of the clamping tool in this embodiment. It is the block diagram which showed the structure of the control circuit of the clamping tool in this embodiment. It is a timing chart which detects the hit | damage start of the clamping tool in this embodiment. It is the flowchart which showed the control method of the clamping tool in this embodiment. It is a graph which shows the relationship between the impact time of the clamping tool in this embodiment, and a clamping torque. It is explanatory drawing which showed the attachment method of the wheel nut by the clamping tool in this embodiment. It is explanatory drawing which showed the usage method of a torque wrench.

  Below, the tightening tool in this embodiment is demonstrated, referring drawings. The tightening tool in the present embodiment is an impact wrench A for tightening a wheel nut for automobile tire replacement work. As shown in FIG. 1, the impact wrench A has a fuselage housing part 50 and an upper part of the fuselage housing part. 50 is provided with an operation panel housing portion 52 disposed at a lower portion of the battery pack 50 and a battery pack portion 6 detachably disposed at a lower portion of the operation panel housing portion 52.

  As shown in FIG. 2, the fuselage housing unit 50 includes a drive motor 2 at the rear end thereof, an inverter circuit 3 for driving the drive motor 2, and a control circuit unit 4 for controlling the inverter circuit 3 at the lower end thereof. It has. The drive motor 2, the inverter circuit 3, and the control circuit unit 4 will be described in detail later.

  In addition, a transmission mechanism 5 for transmitting the rotational power of the drive motor 2 to a nut gripping cylinder 41 that is a tip tool (not shown) is disposed at an intermediate portion of the body housing portion 50. Furthermore, an anvil 13 as a wrench rotation shaft that transmits the rotational impact force of the transmission mechanism 5 to the tip tool is attached to the tip portion of the body housing portion 50.

  As shown in FIG. 2, the transmission mechanism unit 5 includes a reduction mechanism unit 9 including a planetary gear 7 and a ring gear 8 that engage with a gear 31 attached to the output shaft of the drive motor 2, a spindle 10, and a spindle. On the anvil 13 and the anvil 13, which can hold the nut gripping cylinder 41, the impact mechanism portion 5 a composed of a hammer 12 urged toward the anvil 13, which will be described later, by a spring 11 that is arranged to be movable back and forth on 10. It is provided with a protrusion 13a that engages with the protrusion 12a of the hammer 12 and rotates the anvil 13 when a hammering impact of the hammer 12 is applied.

  The operation of the transmission mechanism unit 5 when the impact wrench A is driven will be described. First, rotation is transmitted from the spindle 10 to the anvil 13 via the hammer 12 while the load is small. That is, the rotation of the spindle 10 is transmitted to the anvil 13 in a state where the protrusion 12 a of the hammer 12 and the anvil 13 (protrusion 13 a) are engaged.

  On the other hand, when the load increases, the hammer 12 moves back toward the drive motor against the elastic force of the spring 11 (right direction in FIG. 2) and receives the bias of the elastic force of the spring 11. Rotate in state. Thereafter, when the protrusion 12a of the hammer 12 gets over the protrusion 13a of the anvil 13 as the spindle 10 rotates, the hammer 12 moves forward (to the left in FIG. 2), and the protrusion 12a of the hammer 12 moves to the anvil. By colliding with the 13 projections 13 a, the hammer 12 applies a striking force generated by the collision to the anvil 13 as a rotational force, and transmits the rotation and striking force to the nut gripping cylinder 41 to perform the screw tightening operation. By alternately moving the hammer 12 forward and backward, it is possible to continuously perform screw tightening operations by applying a rotational force and a striking force to the anvil 13.

  A trigger switch 14 that adjusts the rotational speed of the drive motor 2 is disposed at the center of the body housing portion 50. The operator can adjust and drive the output torque of the impact wrench A by the pulling operation and the pulling amount of the trigger switch 14. A forward / reverse switching lever 15 for switching forward / reverse rotation of the drive motor 2 is provided above the trigger switch 14. When the trigger switch 14 is operated with the forward / reverse switching lever 15 in the forward rotation side, the nut gripping cylinder 41 rotates in the clockwise direction and can be tightened with a screw or the like. Conversely, when the forward / reverse switching lever 15 is set to the reverse side, the drive motor 2 can be rotated counterclockwise to loosen a screw or the like. The forward / reverse switching of the drive motor 2 may be switched between forward rotation and reverse rotation each time it is pressed by a push button arranged in the impact wrench A, and is not limited to the lever system.

  The battery pack unit 6 is detachably mounted on a battery pack case 6a that is disposed at the lower end of the body housing unit 50 and accommodates a battery pack (not shown) made of a lithium ion battery serving as a drive power source for the drive motor 2. Has been. Note that the external power source of the drive motor 2 is not limited to a lithium ion battery, and a nickel-cadmium battery, a nickel metal hydride battery, or a commercial AC power source may be used.

  As shown in FIG. 3, on the surface of the operation panel housing portion 52, a single / continuous display lamp 53, a strength display lamp 54, a battery remaining amount display panel 55, a battery remaining amount display switch 56, a light on / off switch 57. Is arranged.

  Further, a single / repetitive changeover switch 58 and a strength changeover switch 59 are disposed on the side surface of the operation panel housing portion 52.

  When the single / repetitive changeover switch 58 is operated to set the continuous mode, the drive motor 2 rotates and rotates the anvil 13 via the hammer 12 while the trigger switch 14 is operated (while it is retracted). The rotational force and the striking force are transmitted to the nut, and the nut gripping cylinder 41 can be used to tighten a screw or the like.

  On the other hand, when the single shot / repetitive changeover switch 58 is operated to set the single shot mode, the collision between the hammer 12 and the anvil 13, that is, the impact (impact operation) is output from the impact detection sensor 27. When a predetermined time (0.8 seconds) is struck, the drive motor 2 is stopped regardless of the operation of the trigger switch 14, and the tightening operation of the wheel nut is stopped.

  As shown in FIG. 3, the strength changeover switch 59 is a switch that can set four levels of striking force in this embodiment. As shown in FIG. 4, by operating this strength changeover switch 59 several times, the rotational speed of the drive motor can be adjusted in four stages of 2600 rpm, 2000 rpm, 1200 rpm, 800 rpm. The rotation mode can be set.

  Next, the structure of the drive motor 2 will be described with reference to FIG. As shown in FIG. 5, the drive motor 2 is a brushless DC motor. The drive motor 2 is not limited to a brushless DC motor, and may be a commutator motor.

  The drive motor 2 includes a rotor 2a configured by embedding two pairs of permanent magnets 2c, and six salient poles 2e. The salient pole 2e has a three-phase stator of U phase, V phase, and W phase. A stator 2b around which a winding 2d is wound is provided. Note that the structure of the rotor 2a and the stator 2b, such as the arrangement of the permanent magnets 2c and the number of permanent magnets, and the number of salient poles of the stator 2b, are not limited to those described above.

  Further, a plurality of magnetic sensors, for example, Hall ICs 17 to 19 (shown in FIG. 6) are provided so as to correspond to the permanent magnet 2c of the rotor 2a, and the magnetic force of the permanent magnet 2c is detected by the Hall ICs 17 to 19. The rotational position of the rotor 1a can be detected. In the drive motor 2 in this configuration, the drive motor 2 rotates the rotor 2a by energizing an appropriate stator winding 2d based on the rotation position detection signal of the rotor 2a detected by the Hall ICs 17-19. 2 can be driven. Further, as will be described later, the rotational speed of the drive motor 2 can be detected based on the rotor information from the Hall ICs 17 to 19.

  Next, the configuration of the drive circuit of the drive motor 2 will be described with reference to FIGS. As shown in FIG. 2, the drive circuit of the drive motor 2 includes an inverter circuit 3, a control circuit unit 4, and the battery pack unit 6.

  As shown in FIG. 6, the inverter circuit 3 is composed of, for example, a three-phase inverter in which six switching elements Q1 to Q6 are connected in a three-phase bridge, and according to a signal from the control circuit unit 4 as described later. Then, the DC voltage supplied from the battery pack unit 6 is switched through the control signal output circuit 29, and the energization to the stator winding 2d of each phase is switched at a predetermined timing to drive the drive motor 2. In addition, the voltage applied to the drive motor 2 is controlled by PWM control of the switching elements Q1 to Q6, and the output torque of the drive motor 2 is controlled.

  That is, by controlling the motor applied voltage, that is, the motor input, it is possible to control the motor output torque, that is, the motor driving current. That is, when the motor applied voltage is large, the motor output torque is large, and when it is small, the torque is small. Depending on the operating condition of the drive motor 2, a large current flows through the switching elements Q1 to Q6, and high-speed switching is performed. Therefore, the switching elements Q1 to Q6 generate a large amount of heat, and the inverter circuit 3 is forcibly cooled. A method is needed.

  As a countermeasure, a wind window is provided by a fan (not shown) that rotates together with the drive motor 2 by providing a wind window on the portion of the fuselage housing 50 where the switching elements Q1 to Q6 are provided, that is, on the side opposite to the motor side of the inverter circuit 3 shown in FIG. Cooling is achieved by arranging the switching elements Q1 to Q6 in the flow path of the air sucked from the air.

  As shown in FIG. 6, the control circuit unit 4 includes a calculation unit 20, an applied voltage setting circuit 21, an applied voltage maximum value setting circuit 22, a rotation direction setting circuit 23, a rotor position detection circuit 24, a rotation speed detection circuit 25, The impact detection circuit 26 includes a impact detection circuit 26, a temperature rise measurement circuit 28, and a control signal output circuit 29.

  The arithmetic unit 20 has a timer (not shown) for outputting a drive signal based on the processing program and data, a ROM for storing a program and control data corresponding to a flowchart to be described later, and a temporary storage for data. It is constituted by a microcomputer including a RAM, a timer and the like.

  When the applied voltage maximum value setting circuit 22 detects the operation of the strength changeover switch 59, the applied voltage maximum value setting circuit 22 changes the maximum value of the applied voltage of the drive motor 2 in a stepwise manner. In this embodiment, it can be set in four stages, and the PWM duty of the switching elements Q1 to Q6 can be set to 20%, 45%, 75%, and 100% each time the strength changeover switch 59 is pressed.

  Based on the setting signal from the applied voltage maximum value setting circuit 22 and the pulling amount of the trigger switch 14, the applied voltage setting circuit 21 sets the maximum motor applied voltage set by the strength changeover switch 59 even when the trigger switch 14 is fully pulled. When the value does not exceed the value, an applied voltage to be supplied to the drive motor 2, that is, a PWM duty of the switching elements Q1 to Q6 described later is set in conjunction with the pulling amount of the trigger switch 14, and otherwise, the set motor applied voltage is set. The maximum value is set.

  The rotor position detection circuit 24 detects the outputs of the Hall ICs 17 to 19 and detects the rotor position of the drive motor 2 based on the signals. The rotor position detection means of the drive motor 2 may be a sensorless system that detects the rotor position based on the induced voltage of the stator winding 2d, and is limited to the rotor position detection circuit 24 using the Hall ICs 17 to 19 described above. It is not something that can be done.

  The rotation speed detection circuit 25 detects the motor rotation speed from the time interval of the signals of the three-phase stator winding 2d output from the Hall ICs 17-19.

  The control signal output circuit 29 supplies a PWM signal to the switching elements Q1 to Q6 based on the output from the arithmetic unit 20. By controlling the pulse width of the PWM signal, the number of rotations of the drive motor 2 in the rotation direction set by adjusting the power supplied to each armature winding U, V, W can be controlled.

  Further, a hitting impact detection sensor 27 for detecting an impact caused by hitting during an impact operation is disposed on the control circuit unit 4. The signal from the impact detection sensor 27 is an analog signal having a different amplitude, period, and frequency depending on the impact of the impact, and this analog signal is digital so that the operation unit 20 described later can be recognized by the impact detection circuit 26. Signal or pulse signal. In the present embodiment, an acceleration sensor using a piezoelectric effect is used as the impact detection sensor 27. However, the impact sensor is not limited to the acceleration sensor as long as it can detect an impact.

  The arithmetic unit 20 controls the motor applied voltage by PWM control of the switching elements Q1 to Q6 of the inverter circuit 3 based on the information of the applied voltage setting circuit 21 and the information of the applied voltage maximum value setting circuit 22, and the rotation direction. Based on information from the setting circuit 23 and the rotor position detection circuit 24, the predetermined switching elements Q1 to Q6 are switched to energize the predetermined stator winding 2d to rotate the drive motor 2 in the set rotation direction. Let

  Further, the drive motor 2 is controlled according to the operation mode set by the mode switch 30. Based on the output signal of the rotational speed detection circuit 25, the rotational speed of the drive motor 2 is detected and the impact operation is detected. A signal from the impact detection sensor 27 is input via the impact detection circuit 26 to detect an impact (impact action).

  Next, the control method of the impact wrench A, which is the main object of the present invention, will be described. In the present invention, the impact detection sensor 27 is used as a detection method for the impact operation.

  The impact detection sensor 27 outputs a detection signal when detecting an impact at the time of impact impact, detects the detection signal by the impact impact detection circuit 26, and outputs the information to the calculation unit 20. The signal output from the impact detection circuit 26 is composed of a plurality of pulse signals. The pulse signal is proportional to the impact impact force, and the greater the impact force, the more pulse signals are output.

  That is, the greater the motor applied voltage (PWM duty) and the greater the motor output, the greater the impact force, so the impact sensor 27 outputs more impact signals to the impact sensor 26 in a single impact operation. The impact detection circuit 26 converts this signal into a pulse signal that can be recognized by the calculation unit 20 and outputs the pulse signal to the calculation unit 20.

  As shown in FIG. 7, when the arithmetic unit 20 detects a pulse signal from the impact detection circuit 26 at time T, the internal counter is activated to start counting for a predetermined time Ta, and within a predetermined time Ta range in advance. When the set number of pulse signals are counted, it is determined that there has been an impact action impact.

  Specifically, as shown in Table 1, the predetermined time Ta for detecting the impact impact and the count value for detecting the pulse signal are variable according to the magnitude of the motor applied voltage (PWM duty), and the motor applied voltage is 20%. 45% and 1 count, and 75% and 100% count 2 times. Thereby, it is possible to more reliably perform hit detection using the hit impact detection sensor 27.

  Next, a control method of the control circuit will be described in detail with reference to FIG. First, as shown in FIG. 8, when the drive motor 2 is started in the single-shot mode (S100), the arithmetic unit 20 detects the presence or absence of a pulse signal obtained by converting the signal from the impact detection sensor 27 by the impact detection circuit 26. (S301). When a signal from the impact detection sensor 27, that is, a pulse signal is detected (Yes in S301), the number of pulses CNT_S of the pulse signal is counted (S302), and a timer for measuring a predetermined time Ta has started time measurement. Is determined (S303).

  When time measurement has not started (Yes in S303), that is, when a pulse signal is detected for the first time at time T shown in FIG. 7, a timer for a predetermined time Ta is started (S304), and within the predetermined time Ta The number of pulses at CNT_S is counted. Thereafter, it is determined whether or not the predetermined time Ta has elapsed (S305). If not, the process returns to S301.

  On the other hand, if the pulse signal is not detected in S301 (No in S301), the process proceeds to S305, but since the timer has not started, it is determined in S305 that the predetermined time Ta has not elapsed, the process returns to S301, and the pulse signal is This process is repeated until it is detected. If the timer has already been started in S303, the process proceeds to S305 without restarting the timer, and the pulse signal number CNT_S is counted until a predetermined time Ta elapses.

  In S305, when the predetermined time Ta has elapsed since the timer was started at time T, the threshold value CNT_th of the number of pulse signals within the predetermined time Ta corresponding to the motor applied voltage (PWM duty) is set. This threshold value CNT_th is stored in advance in the arithmetic unit as shown in FIG. 6, and is set according to the motor applied voltage (S306). As the motor applied voltage (PWM duty) increases, the impact torque increases, so the signal from the impact detection sensor 27, that is, the pulse signal also increases. Therefore, when the motor applied voltage is large, the threshold is set larger than when the motor applied voltage is small.

  Thereafter, the actual number of pulse signals CNT_S is compared with the set threshold value CNT_th (S307). If the number of pulse signals is larger than the threshold value, it is determined that the impact operation has been performed once (S308).

Thereafter, the timer Tb is started (S309), and it is determined whether or not 0.8 seconds have elapsed. If it has elapsed, the motor is stopped and the impact operation is ended (S311).
Although the present invention has been described above, the time from hit detection to stop is not limited to 0.8 seconds, but should be determined according to the bolt size and the material to be fastened.

  In the impact wrench A of the present invention, a wrench rotation shaft is linked to the output shaft of the drive motor via a striking mechanism, and a nut gripping cylinder 41 is detachably connected to the tip of the wrench rotation shaft. In order to fix the tire wheel 60 (shown in FIG. 10) to the hub, a wheel nut 62 screwed to a wheel bolt is configured to be tightened with a specified torque by the nut gripping cylinder 41.

  That is, the impact wrench A in the present embodiment is configured such that the tightening torque is determined based on the relationship between the rotation speed of the drive motor 2 and the impact time. The impact wrench A in this embodiment has four stages of tightening torque modes, and in each of the tightening torque modes, the rotational speed of the drive motor can be changed from small to large.

  As shown in FIG. 4, in each tightening torque mode, the rotation of the drive motor 2 can be set in four stages from weak to strong depending on the number of times the strong / weak switch 59 is pressed. Depending on the number of times the strength changeover switch 59 is pressed, the switch selection information is supplied to the arithmetic unit 20, and the arithmetic unit supplies the control signal output circuit 29. The control signal output circuit 29 is based on the output from the arithmetic unit 20. The PWM signal is supplied to the switching elements Q1 to Q6. The number of rotations of the drive motor 2 in the rotational direction set by adjusting the power supplied to each armature winding U, V, W by controlling the pulse width of the PWM signal is controlled.

  In this way, the rotational speed of the drive motor 2 is set to four stages of rotation modes of 2600 times / minute, 2000 times / minute, 1200 times / minute, and 800 times / minute.

  FIG. 9 is a graph showing the relationship between the impact time and the tightening torque. As shown in FIG. 9, in each tightening torque mode, a curve is drawn such that the tightening torque increases as the impact time elapses.

  In the impact wrench A having such characteristics, the striking operation is stopped after 0.8 seconds regardless of each tightening torque mode. That is, the control circuit unit 4 stops the drive motor 2 by detecting that a predetermined time has elapsed after detecting the output signal from the impact detection sensor 27. Table 1 shows the tightening torque in each tightening torque mode that stops after 0.8 seconds from the start of tightening.

  As shown in Table 2, when the impact time is completed after 0.8 seconds, the tightening torque in the switching “1” mode is about 30 N · m, and the tightening torque in the switching “2” mode is about 50 N. M, the tightening torque in the switching “3” mode is approximately 70 N · m, and the tightening torque in the switching “4” mode is approximately 90 N · m. As described above, the rotation mode selected by the strength switching switch 59 is configured to correspond to four tightening torque modes in which the tightening torque appropriately defined in advance according to the vehicle type is classified into four stages. Yes.

  Next, a method for tightening a tire for an automobile using the impact wrench A having the above-described tightening characteristics will be described. First, the nut gripping cylinder 41 is attached to the tip of the anvil 13. Next, the forward / reverse switching lever 15 is pushed to set the rotation direction of the anvil 13. Further, a battery pack case 6 a containing a lithium ion battery is attached to the battery pack unit 6.

  Thereafter, as shown in FIG. 10, in order to fix the tire wheel 60 of the automobile to the hub, the wheel nut 62 that is screwed to the wheel bolt is held by the nut holding cylinder 41, and thereafter various settings of the impact wrench A are made. Do. That is, the single / repetitive changeover switch 58 is operated to set the single-shot mode, and the strong / weak changeover switch 59 is operated several times so that the rotational speed of the drive motor is 2600 rpm / 2000, 2000 rpm / 1200, 1200 rpm. Set the rotation mode to either 1 / min or 800 rpm.

  Then, while holding the impact wrench A, the nut gripping cylinder 41 is brought into contact with the wheel bolt, and then the trigger switch 14 is retracted. Then, impact is started by the impact wrench A, and tightening is stopped 0.8 seconds after the start of impact. As a result, the impact wrench A in the present embodiment is used to tighten until just before the specified torque.

  Finally, as shown in FIG. 11, the torque wrench 61 set to the specified torque is tightened until a “click” sound is heard. Thereby, it can confirm that it tightened with the prescription | regulation torque. As a result, the impact wrench A according to the present embodiment is used to tighten to a level just before the specified torque, so that the tightening operation up to the specified torque can be shortened.

  The impact wrench A of the present embodiment is tightened with the same striking time even when the tightening torque of a normal vehicle and the tightening torque of a light vehicle are different. Table 3 shows a setting example of the tightening torque of the ordinary vehicle and the tightening torque of the light vehicle.

  That is, regardless of the vehicle type, the time from the start of impact to the end of tightening is made constant at 0.8 seconds, and the tightening with the specified torque in the vehicle type is achieved by the rotational speed of the drive motor 2. In this way, the tightening torque according to the vehicle type in each tightening torque mode does not cause variation among workers regardless of the worker performing the tightening work, and it is not necessary to be an expert. Can work with peace of mind and perform stable torque management. Furthermore, by selecting a tightening torque mode corresponding to the vehicle type for tire replacement, it is possible to handle tire replacement for all vehicle types with a single tightening tool.

  As a result, by selecting the rotation mode classified by the operator, the drive time of the drive motor 2 until the tightening of the wheel nut 62 within a predetermined time is constant in the selected rotation mode. Since the automatic stop is performed before reaching the tightening torque defined as appropriate, it is possible to prevent the wheel bolt from being broken and the wheel nut from being damaged due to excessive tightening.

A Impact wrench 2 Drive motor 4 Control circuit section 5 Transmission mechanism section 13 Anvil (wrench rotation shaft)
5a Impact mechanism section 27 Impact detection sensor 62 Wheel nut

Claims (3)

A wrench rotary shaft is linked to the output shaft of the drive motor via the transmission mechanism,
A nut nut that can be attached to and detached from the tip of the wrench rotating shaft is detachably connected, and the wheel nut for exchanging automobile tires is configured such that the wheel nut is tightened to a specified torque via the nut gripping cylinder by rotation of the wrench rotating shaft. In the tightening tool,
The number of rotations of the drive motor until the tightening of the wheel nuts within a predetermined time is controlled to be classified into a plurality of rotation modes by the control circuit unit,
The classified rotation modes are configured to correspond to a plurality of tightening torque modes in which the tightening torque properly defined in advance according to the vehicle type is classified into several stages,
A wheel nut tightening tool for replacing a vehicle tire, wherein an appropriate tightening torque to the wheel nut is achieved by the end of rotation of the drive motor. The transmission mechanism includes an impact mechanism that converts a continuous rotation operation of the drive motor into a batting operation that is an intermittent rotation operation, and a batting impact that detects the batting operation of the impact mechanism and outputs an output signal. A detection sensor,
The control circuit unit controls the drive motor to stop by detecting that a predetermined time has elapsed after detecting an output signal from the impact detection sensor. Wheel nut tightening tool for automotive tire replacement as described.   3. The wheel nut tightening tool for replacing a vehicle tire according to claim 1, wherein the time from the start of hitting to the end of hitting in each tightening torque mode is the same. 4.