JP2002273667A - Impact wrench - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an impact wrench that can effect a reliable tightening operation by detecting electrical noise mixed in a torque signal and preventing a malfunction of the impact wrench despite a simple circuit structure. SOLUTION: The impact wrench 1 comprises a torque generating means 5 for generating pulse torque, a driving means 4 for driving the torque generating means 5, rotary shafts 9 and 10 engaged with a given screw part and rotated by the pulse torque to screw the engaged screw part into a given screwed part, a torque signal converting means 6 for converting the pulse torque into a pulse torque signal corresponding to a torque vague, a pulse counting means 22 for counting the number of pulses in the pulse torque signal, a pulse number comparing means 23 for comparing a preset pulse number and the pulse number counted by the pulse counting means 22 in a given time, and a stopping means 24 for stopping the driving means 4 according to the comparison result.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impact wrench for controlling a tightening torque, and more particularly to an impact wrench for detecting an abnormal tightening torque.

[0002]

2. Description of the Related Art A conventional impact wrench includes a rotating shaft,
It is configured to include a motor, a pulse unit that generates a pulsed torque, and a torque sensor that detects the torque, and the pulse unit is rotated by the motor to generate a pulsed torque, and the torque is applied to a rotating shaft. Had been raised. The impact wrench includes a controller that is electrically connected to the impact wrench and controls operation. The controller detects an electric signal from the torque sensor as a torque signal through an electric filter, and outputs the torque signal. The tightening torque was controlled based on the above.

[0003]

According to the conventional impact wrench as described above, a pulse-like torque is detected by an electric signal from a torque sensor. Noise was sometimes mixed. Since it is difficult to remove such electrical noise with an electrical filter, the electrical noise is input to the controller as a torque signal while being mixed. For this reason, when such an electrical noise is mixed into the torque signal, the impact wrench may malfunction and cause abnormal fastening such as insufficient fastening.

Accordingly, the present invention provides a highly reliable tightening operation by detecting electrical noise mixed in a torque signal to prevent malfunction of an impact wrench, while having a simple circuit configuration. An object of the present invention is to provide an impact wrench capable of performing the following.

[0005]

In order to achieve the above object, an impact wrench according to the first aspect of the present invention includes a torque generating means for generating a pulsed torque as shown in FIGS. Driving means 4 for driving torque generating means 5; rotating shaft 9 which engages with a predetermined threaded component, rotates by the pulsed torque, and screws the engaged threaded component into a predetermined threaded component. A torque signal converting means 6 for converting the pulsed torque into a pulse torque signal corresponding to the torque value; and a pulse counting means 22 for counting the number of pulses of the pulse torque signal.
A pulse number comparing means 23 for comparing a preset pulse number with a pulse number counted within a predetermined time by the pulse counting means 22; and a driving means 4 based on a comparison result of the pulse number comparing means 23. And stopping means 24 for stopping the operation.

With this configuration, the pulse counting means 2
2 and the number-of-pulses comparing means 23, the comparison result can be obtained by comparing the number of pulses set in advance with the number of pulses counted within a predetermined time. Further, since the stop means 24 is provided, the drive means 4 can be stopped based on the comparison result, so that the electric noise mixed in the torque signal can be detected and the erroneous operation of the impact wrench 1 can be detected with a simple circuit configuration. Operation can be prevented.

According to a second aspect of the present invention, the impact wrench according to the first aspect includes a torque control unit that stops the driving unit when the pulse torque signal value exceeds a threshold value. Good.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or corresponding members are denoted by the same or similar reference numerals, and duplicate description is omitted.

FIG. 1 is a schematic partial sectional view showing the structure of an impact wrench 1 according to a first embodiment of the present invention. The impact wrench 1 includes a case 2 and a grip 3. The case 2 incorporates an electric motor 4 as driving means and an oil pulse unit 5 as torque generating means. In the present embodiment, the torque generating means is an oil pulse unit. However, the torque generating means may generate a pulsed torque by, for example, connecting and disconnecting a clutch.

The oil pulse unit 5 includes an electric motor 4
To generate a hydraulic pressure P, and the generated hydraulic pressure P generates a pulsed torque T. The case 2 has a built-in torque sensor 6 for measuring the generated hydraulic pressure P. The torque sensor 6 is a converter that converts the hydraulic pressure P into an electric signal. When the hydraulic pressure P increases or decreases, the torque T increases or decreases as the hydraulic pressure P increases or decreases. Therefore, measuring the hydraulic pressure P corresponds to measuring the torque T. Therefore, the torque sensor 6 functions as torque signal conversion means. The torque T is converted by the torque sensor 6 into a pulse torque signal. The pulse torque signal is typically an electric signal. And the torque T corresponds to the pulse height of this pulse torque signal. In addition, instead of the torque sensor 6,
A strain gauge (not shown) may be attached to the rotating shaft 9 and used. Alternatively, a non-contact torque sensor may be used.

The grip 3 is formed in a shape that is easy for the user to use, and includes a trigger switch 7 and a connector 8 at the bottom. When the user presses the trigger switch 7, the electric motor 4 starts. The connector 16 has a cable 16
(See FIG. 2), and the controller 11 (see FIG.
See). The torque T generated by the oil pulse unit 5 can be taken out by the rotation of the rotating shaft 9 protruding from the case 2. Further, a socket 10 for screwing a threaded component into a predetermined threaded component is coupled to the tip of the rotating shaft 9.

FIG. 2 shows an impact wrench 1 (see FIG. 1).
1 is a block diagram illustrating a schematic configuration of a controller 11 of FIG. The controller 11 includes a control unit 21 and a storage unit 31
, A display unit 12, an input unit 13, a connector 14, and a power supply connector 15.

The display unit 12 can display, for example, a set torque, a torque T, and a tightening abnormality set by a user. The input unit 13 allows a user to input a desired torque or the like.

The storage unit 31 stores a cutoff torque 32 as a threshold value and a pulse monitoring time interval 33 as a predetermined time.
And the normal pulse number 34 as a preset pulse number
And the set rotation speed 35 of the electric motor 4 are stored. The cut-off torque 32 is typically a set torque. For example, if an error occurs between the actual tightening torque of the screw component and the set torque, the cut-off torque 32 is set to a value that corrects the error. You may make it set automatically.
The predetermined time, that is, the pulse monitoring time interval 33 is, for example, 0.2
The time may be set to 0.3 seconds, but an optimal time is set in consideration of the characteristics of the pulse torque signal. The normal pulse number 34 is the number of pulses that can be generated in the pulse monitoring time interval 33 if it is normal.

The control unit 21 controls the impact wrench 1 via the connector 14 and the cable 16.
The control unit 21 includes a pulse counting unit 22 as a pulse counting unit and a pulse comparing unit 23 as a pulse number comparing unit.
And a torque control unit 24 as a torque control means. The torque control unit 24 is also a stopping unit. The control unit 21 is typically a combination of logic circuits, but may be a microcomputer.

The pulse counting section 22 receives a pulse torque signal from the torque sensor 6 (see FIG. 1) and counts the number of actual pulses which is the number of pulses of the pulse torque signal input within the pulse monitoring time interval 33. Further, the pulse counting unit 2
2 continuously counts the number of actual pulses while the pulse torque signal is being input, that is, while the torque T is being generated, at every pulse monitoring time interval 33 (see FIG. 3A). The numbers are sequentially output to the pulse comparison unit 23. Also, the counting of the actual number of pulses is typically started at the starting point of the input pulse torque signal. For example, a pulse indicating that the screw component has tightened to some extent and the torque T has settled to some extent is generated several times. It may be a point in time after the occurrence. In addition, the pulse counting unit 22 may be configured to input only pulses whose pulse height of the pulse torque signal is equal to or greater than a certain value. By doing so, the pulse counting unit 22 does not count, for example, small electrical noise (low pulse height) among the electrical noises mixed in the pulse torque signal, and thus can count only the electrical noise that is originally desired to be detected.

Referring to FIGS. 3 and 4, electric noise mixed into the pulse torque signal will be described. Among the mixed electric noises, there are those having a pulse shape similar to the pulse shape of the torque T.
Further, among such electrical noises, there are those having a high value (high pulse height). When the torque control unit 24 described later inputs this electric noise, it determines that the cutoff torque 32 has been reached, stops the electric motor 4, and treats that the tightening work has been completed normally. Therefore, there is a possibility that a product that has not reached the set tightening torque may be shipped as it is.

In the method of counting the actual number of pulses by the pulse counting unit 22, the number of actual pulses during the generation of the torque T is not continuously counted at every pulse monitoring time interval Δt as described above. The number of actual pulses may be counted only for the first pulse monitoring time interval Δt (see FIG. 3B). In this way, when noise often occurs at the beginning of the pulse torque signal, without lowering the monitoring accuracy,
The number of times of counting by the pulse counting unit 22 can be greatly reduced.

The pulse counting section 22 may count the actual number of pulses within the past pulse monitoring time interval Δt every time one pulse is input (see FIG. 4A). in this case,
As shown in the figure, when the actual pulse number in the past Δt is counted from the occurrence of noise, even if the counted actual pulse number is the same as the normal pulse number, it is surely counted in the next pulse more than the normal pulse number. You. By doing so, the pulse counting unit 2
In No. 2, since the number of actual pulses is counted for each pulse, noise can be detected more quickly. Further, when the torque T reaches the cutoff torque 32, the number of actual pulses within the past pulse monitoring time interval Δt may be counted (see FIG. 4B). In this case, for example, the number of pulses generated within the monitoring time interval Δt may be counted based on the number of pulse torque signals input and stored in the past by a microcomputer and a clock (not shown). This way,
Since only the noise originally desired to be detected can be detected, the number of times of counting by the pulse counting unit 22 can be greatly reduced without lowering the monitoring accuracy.

The pulse comparing section 23 compares the actual number of pulses counted by the pulse counting section 22 with the normal pulse number 34 and outputs the result of the comparison to the torque control section 24. If the comparison result by the pulse comparison unit 23 indicates, for example, that the actual number of pulses is greater than the normal number of pulses 34, it is determined that the electrical noise is mixed, that is, it is determined to be abnormal. At this time, the pulse comparison unit 23 sets the past pulse monitoring time interval 33
Since the number of actual pulses that have occurred within the period is compared, if it is determined that an abnormality has occurred, it is determined that an abnormality has occurred within the past pulse monitoring time interval 33.

The torque control section 24 controls the electric motor 4. For example, when the trigger switch 7 of the impact wrench 1 is operated, the torque control unit 24 sends a motor power to the electric motor 4, the electric motor 4 rotates at a preset rotation speed 35, and the torque T becomes a cutoff torque. 3
When the number reaches 2, the motor voltage is controlled so as to stop the electric motor 4. The torque control unit 24 controls the motor voltage so as to stop the electric motor 4 when an abnormal comparison result is input from the pulse comparison unit 23. Further, the driving time of the electric motor 4 may be set in advance, and if the torque T does not reach the cutoff torque 32 within the set time, the electric motor 4 may be stopped.

A cable 16 is attached to the connector 14, and the impact wrench 1 and the controller 11 are connected by the cable 16. The pulse torque signal from the torque sensor 6 is sent to the control unit 21 via the cable 16, and the motor power is sent from the control unit 21 to the electric motor 4 via the cable 16. Also, the power connector 15
, An external power supply 18 is connected to the controller 11.

Next, the operation of the impact wrench 1 will be described with reference to FIGS.

The socket 10 is connected to the rotating shaft 9. The connector 8 of the impact wrench 1 and the connector 14 of the controller 11 are connected by a cable 16. An external power supply 18 is connected to a power supply connector 15 of the controller 11.

Next, a tightening torque of a work (not shown) (threaded part and threaded part) is set by the input unit 13. Then, the set torque is stored in the storage unit 31 as the cutoff torque 32.

Next, the user grips the grip 3, engages the tip of the socket 10 with a threaded component (not shown), and pulls the trigger switch 7 forward. The control unit 21 detects that the trigger switch 7 has been pulled, and sets the electric motor 4 at the set rotation speed 35 stored in the storage unit 31 by the torque control unit 24.
To rotate. The rotation of the electric motor 4 causes the oil pulse unit 5 to generate a pulsed torque T, and the socket 10 rotates. The screw component is screwed into a threaded component (not shown) by the rotation of the socket 10.

At the same time, the torque sensor 6 measures the torque T and outputs a pulse torque signal to the control unit 21. When the control section 21 receives the pulse torque signal, the pulse counting section 22 counts the number of actual pulses input within the pulse monitoring time interval 33. Then, the actual number of pulses is sequentially output to the pulse comparison unit 23.

The pulse comparing section 23, which receives the actual pulse number from the pulse counting section 22, outputs the actual pulse number and the normal pulse number 3
Compare with 4. When the actual number of pulses is equal to or smaller than the normal number of pulses 34, the pulse comparing unit 23 determines that electric noise is not mixed in the pulse torque signal,
The comparison result that the signal is normal is output to the torque control unit 24. If the actual number of pulses is larger than the normal number of pulses 34, it is determined that electric noise is mixed, and a comparison result having an abnormal signal is output to the torque control unit 24. Also,
If the comparison result is normal, the comparison result may not be output to the torque control unit 24. In this way, the pulse comparing section 23 constantly monitors whether or not electric noise is mixed in the pulse torque signal input from the torque sensor 6.

The torque control unit 24 which has received the comparison result from the pulse counting unit 22 continues to rotate the electric motor 4 when the comparison result is normal, and when the comparison result is abnormal, the electric motor 4 4 is stopped, and at the same time, the display unit 12 displays that an abnormality has occurred.

If the comparison result is normal, the torque control unit 24 rotates the electric motor 4 at the set rotation speed 35, and stops the rotation of the electric motor 4 when the torque T exceeds the cutoff torque 32. . Then, the control unit 21
Indication 1 that the tightening operation with the set torque has been completed normally
2 is displayed.

Next, referring to a block diagram of FIG. 5, an impact wrench 10 according to a second embodiment of the present invention will be described.
1 will be described. This figure shows the impact wrench 101
FIG. 2 is a block diagram showing a configuration of a controller 111. The impact wrench 101 has basically the same configuration as the impact wrench 1 in the first embodiment, but includes an air motor 104 instead of the electric motor 4 as driving means. The air motor 104 includes a controllable solenoid valve 104a. Air motor 10
4 is typically a vane motor. The solenoid valve 104a is normally open, that is, the compressed air is supplied to the air motor 104.

The impact wrench 101 includes an oil pulse unit 105 and a torque sensor 106 similar to those of the first embodiment. The oil pulse unit 105 is driven to rotate by an air motor 104, and a pulse torque T Is generated, and the torque sensor 106
The pulse torque T is converted into a pulse torque signal. The pulse torque signal is typically an electric signal. And the torque T corresponds to the pulse height of this pulse torque signal.

Further, the impact wrench 101 includes a start valve 107, a connector 108a, and an air connector 108b instead of the trigger switch 7. The start valve 107 is normally in a closed state, and is opened by pressing the start valve 107. When the user presses the start valve 107, the air motor 104 is started. A cable 116 is attached to the connector 108a, and is connected to the controller 111. An air hose 119 is attached to the air connector 108b to supply compressed air to the impact wrench 101.

The controller 111 includes a control unit 121, a storage unit 131, and a display unit 1 as in the first embodiment.
12, an input unit 113, a connector 114, and a power supply connector 115.

The storage section 131 stores a cutoff torque 132 as a threshold, a pulse monitoring time interval 133 as a predetermined time, and a normal pulse number 134 as a preset number of pulses. And cutoff torque 1
32, pulse monitoring time interval 133, normal pulse number 134
Are set in the same way as in the first embodiment.

The control unit 121 includes a controller 111,
The control unit 121 controls the impact wrench 101 via the cable 116. The control unit 121 includes a pulse counting unit 122 as a pulse counting unit, a pulse comparing unit 123 as a pulse number comparing unit, and a torque controlling unit. A solenoid control unit 124 is provided. Further, the solenoid control section 124 is also a stopping means. The pulse counting section 122 and the pulse comparing section 123 are the same as those described in the first embodiment.

The solenoid control unit 124 controls the air motor 1
04 is controlled. For example, the solenoid control unit 124
Controls the solenoid valve 104a so as to stop the air motor 104 rotating when the start valve 107 of the impact wrench 1 is operated when the torque T reaches the cutoff torque 132. Further, the solenoid control unit 124 controls the solenoid valve 104a so as to stop the air motor 104 when an abnormal comparison result is input from the pulse comparison unit 123. Further, the driving time of the air motor 104 is set in advance, and the torque T is adjusted to the cutoff torque 1 within the set time.
If it does not reach 32, the air motor 104 may be stopped.

The connector 114 has a cable 116 attached thereto, and is connected to the impact wrench 101 and the controller 11.
1 are connected by a cable 116. The pulse torque signal from the torque sensor 106 is sent to the control unit 121 via the cable 116, and is sent to the solenoid valve 104a.
Is supplied from the control unit 121 to the solenoid valve 104a via the cable 116. Further, an external power supply 118 is connected to the controller 111 via the power supply connector 120.

The operation of the impact wrench 101 will be described with reference to FIG.

First, the socket 110 is connected to the rotating shaft 109. Impact wrench 10 by cable 116
The first connector 108a and the connector 114 of the controller 111 are connected. An external power supply 118 is connected to a power supply connector 115 of the controller 111. Then, an air hose 119 is connected to the air connector 108b, and compressed air is supplied to the impact wrench 101.

Next, a tightening torque of a work (not shown) (a screw part and a threaded part) is set by the input unit 113. The set torque is stored in the storage unit 131 as the cutoff torque 132.

Next, the user engages the distal end of the socket 110 with a screw component (not shown) and presses the starting valve 107.
The start valve 107 is opened by being pressed, and the compressed air is supplied to the air motor 104. As a result, the air motor 104 starts rotating. Air motor 1
The oil pulse unit 105 generates a pulse-like torque T by the rotation of 04, and the socket 110 rotates together with the rotating shaft 109. The screw component is screwed into a threaded component (not shown) by the rotation of the socket 110.

At the same time, the torque sensor 106 measures the torque T and outputs a pulse torque signal to the control unit 121.
When the control unit 121 receives the pulse torque signal, the pulse counting unit 122 counts the number of actual pulses input within the pulse monitoring time interval 133. And the actual number of pulses is
The signals are sequentially output to the pulse comparison unit 123.

The pulse comparator 123, which has received the actual number of pulses from the pulse counter 122, compares the actual number of pulses with the normal number of pulses 134. When the actual pulse number is equal to or less than the normal pulse number 134, the pulse comparison unit 123 determines that the pulse torque signal is free of electrical noise and that the signal is normal. Wait for input. If the actual number of pulses is larger than the normal number of pulses 134, it is determined that electric noise is mixed, and a comparison result having an abnormal signal is output to the solenoid control unit 124. In this way, the pulse comparison unit 123 constantly monitors the pulse torque signal input from the torque sensor 106 for any electric noise.

The solenoid control unit 124 that has received the comparison result indicating that the signal is abnormal from the pulse counting unit 22 closes the solenoid valve 104a and shuts off the supply of compressed air to the air motor 104. As a result, the air motor 104 stops. At the same time, the display unit 112 displays that an abnormality has occurred.

If the result of comparison continues to be normal, the solenoid control unit 124 closes the solenoid valve 104a when the torque T exceeds the cutoff torque 132, shuts off the supply of compressed air to the air motor 104, and turns off the air motor. The rotation of 104 is stopped. And the control unit 121
Displays on the display unit 112 that the tightening operation with the set torque has been completed normally.

As described above, the impact wrench 101
Can detect the electric noise mixed in the pulse torque signal and prevent the malfunction of the impact wrench 101 even when the air motor 104 is used as the driving means.

[0048]

As described above, according to the present invention, a torque generating means for generating a pulsed torque, a driving means for driving the torque generating means, a predetermined threaded component, A rotating shaft that is rotated by a torsion-like torque to screw the engaged threaded part into a predetermined threaded part, a torque signal converter that converts the pulse-like torque into a pulse torque signal corresponding to the torque value, A pulse counting means for counting the number of pulses of the pulse torque signal; a pulse number comparing means for comparing a preset pulse number with a pulse number counted within a predetermined time by the pulse counting means; A stopping means for stopping the driving means based on a comparison result of the means, so that the noise mixed in the torque signal can be detected with a simple circuit configuration. And it makes it possible to provide an impact wrench can do work with reliable clamping by preventing malfunction of the impact wrench.

[Brief description of the drawings]

FIG. 1 is a schematic partial sectional view showing a configuration of an impact wrench according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a controller of the impact wrench of FIG. 1;

FIG. 3 is a diagram illustrating electrical noise according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating electrical noise in FIG. 3;

FIG. 5 is a block diagram illustrating a configuration of an impact wrench and a controller according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Impact wrench 2 Case 3 Grip 4 Electric motor 5 Oil pulse unit 6 Torque sensor 7 Trigger switch 8 Connector 9 Rotating shaft 10 Socket 11 Controller 12 Display unit 13 Input unit 14 Connector 15 Power supply connector 16 Cable 21 Control unit 22 Pulse counting unit 23 Pulse comparison unit 24 Torque control unit 31 Storage unit 32 Cut-off torque 33 Pulse monitoring time interval 34 Regular pulse number 35 Set rotation speed

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Hotta Fukushima Prefecture, Shirakawa-shi, Futoshiishi, Yokomine 12 (72) Inventor Takashi Eguchi 1 Toyota Town, Toyota-shi, Aichi Prefecture Toyota Motor Corporation (72) Inventor Tatsuya Mizobe 1 Toyota Town, Toyota City, Aichi Prefecture F-term in Toyota Motor Corporation (reference) 3C038 AA01 AA03 AA04 BC03 BC04 BC07 CA01 CA04 CA06 CB02 CB06 CC04 EA01 EA02 EA03 EA06

Claims (2)

[Claims] A torque generating means for generating a pulse-shaped torque; a driving means for driving the torque-generating means; engaging with a predetermined screw component, and rotating by the pulse-shaped torque; A rotating shaft for screwing the set screw part into a predetermined threaded part; torque signal converting means for converting the pulsed torque into a pulse torque signal corresponding to the torque value; a pulse for counting the number of pulses of the pulse torque signal Counting means; comparing a preset number of pulses with the number of pulses counted within a predetermined time by the pulse counting means; and a pulse number comparing means; Stopping means for stopping the means; impact wrench. 2. The impact wrench according to claim 1, further comprising: torque control means for stopping the driving means when the pulse torque signal value exceeds a threshold value.