Motor driven impact wrench

Abstract

According to the high-precision rechargeable electric impact wrench with no reaction force according to an embodiment of the present invention, by applying a precision torque control function and a shut-off function, bolting work can be performed with an accurate torque value, thereby effectively resolving the problem of inaccuracy in torque control, which was a disadvantage of conventional impact wrenches. With this impact wrench according to an embodiment of the present invention, while retaining the advantages of an impact wrench, such as lightweight, low cost, and working speed, it is possible to achieve torque control precision comparable to that of a torque wrench.

Description

Technology Field

[0001] The present invention relates to an impact wrench, and more specifically, to a high-precision rechargeable electric impact wrench without a reaction force. Background Technology

[0002] An impact wrench is a tool that uses mechanical force to quickly and powerfully tighten nuts that are physically joined to bolts via threads by applying additional force in the rotational direction.

[0003] Impact wrenches come in pneumatic and electric types. Pneumatic impact wrenches are tools that utilize compressed air and are used when the workload is heavy or high torque is required. Electric impact wrenches are powered primarily by a battery, offer good portability, and the workload may vary depending on the battery status.

[0004] The operating mechanism of the impact wrench is such that when a load exceeding a certain amount is applied in the rotational direction, a special internal device hammers in the direction of rotation, applying a force up to the maximum output torque the impact wrench can generate, thereby enabling the tightening or loosening of bolts or nuts, and the rotation direction can be switched between forward and reverse using a rotation direction switching lever.

[0005] Conventional impact wrenches have the advantage of high working speeds (RPM), but they are prone to defects such as material breakage due to the inability to tighten to uniform torque values ​​because torque control is difficult and accuracy is low. Additionally, if unnecessary operation continues even after reaching the maximum torque, there is a risk of safety accidents caused by bolt breakage due to overtightening.

[0006] On the other hand, torque wrenches exist as tools that can be used for tightening or loosening bolts or nuts. Torque wrenches have the advantage of enabling precise torque operation by controlling the motor based on a torque value set by the user. However, torque wrenches have disadvantages, such as the necessity of securing space to support the reaction plate, being heavier than impact wrenches, being more expensive, and having a slower working speed.

[0007] Therefore, there is a need to develop an impact wrench that retains the advantages of lightweight, low cost, and working speed, which are inherent to impact wrenches, while resolving the problem of inaccurate torque control that was a disadvantage of impact wrenches and possessing torque control precision comparable to that of torque wrenches. Prior art literature

[0008] Korean Patent Publication No. 10-2022-0042375 (Published April 5, 2022) Korean Patent Publication No. 10-2022-0041852 (Published April 1, 2022) Korean Patent Registration No. 10-2184633 (Registered November 24, 2020) The problem to be solved

[0009] The present invention aims to provide an impact wrench that can resolve the problem of inaccuracy in torque control, which was a disadvantage of conventional impact wrenches, by enabling bolting work with accurate torque values ​​through the application of a precision torque control function and a shut-off function. means of solving the problem

[0010] According to one aspect of the present invention, an electric impact wrench is disclosed, comprising: an electric motor mounted within a main body housing and including a drive shaft capable of outputting power; a drive unit including a gear set coupled to the drive shaft of the electric motor and linked to the electric motor; a hammer unit connected to the drive unit; a handle housing integrally connected to the main body housing and manufactured in a handle shape in the lower direction of the main body housing; a battery unit mounted at the bottom of the handle housing; an operating switch installed at a predetermined position in the handle housing for user operation regarding whether the electric motor is operated; an operating switch for setting a target torque value; and a control unit mounted within the handle housing, including a motor driver that receives power from the battery unit and transmits a driving signal to the electric motor according to user operation of the operating switch, and performs a shut-off process to forcibly stop the driving of the electric motor when the torque value transmitted to a bolting work object through the hammer unit reaches a predetermined target torque value. Effects of the invention

[0011] According to the impact wrench according to an embodiment of the present invention, by applying a precision torque control function and a shut-off function, bolting work can be performed with an accurate torque value, thereby effectively resolving the problem of inaccuracy in torque control, which was a disadvantage of conventional impact wrenches. Brief explanation of the drawing

[0012] FIGS. 1 and 2 are drawings illustrating the external appearance of a high-precision rechargeable electric impact wrench without a reaction force according to an embodiment of the present invention. FIG. 3 is a block diagram of a high-precision rechargeable electric impact wrench without reaction force according to an embodiment of the present invention. FIG. 4 is a reference drawing for explaining the shut-off function of an electric impact wrench according to an embodiment of the present invention. Specific details for implementing the invention

[0013] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0014] In describing the present invention, detailed descriptions of related prior art are omitted if it is determined that such descriptions may unnecessarily obscure the essence of the invention. Furthermore, numbers used in the description of this specification (e.g., first, second, etc.) are merely identifiers to distinguish one component from another.

[0015] Furthermore, throughout the specification, when a component is referred to as being "connected" or "joined" with another component, it should be understood that the component may be directly connected or joined to the other component, but unless specifically stated otherwise, it may also be connected or joined through an intermediate component. Additionally, throughout the specification, when a part is described as "including" a component, unless specifically stated otherwise, this means that it does not exclude other components but may include additional components. Furthermore, terms such as "part" or "module" as used in the specification refer to a unit that processes at least one function or operation, and this implies that it may be implemented by one or more hardware or software, or a combination of hardware and software.

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

[0018] FIGS. 1 and 2 are drawings illustrating the exterior of a high-precision rechargeable electric impact wrench with no reaction force according to an embodiment of the present invention, FIG. 3 is a block diagram of a high-precision rechargeable electric impact wrench with no reaction force according to an embodiment of the present invention, and FIG. 4 is a reference drawing for explaining the shut-off function of an electric impact wrench according to an embodiment of the present invention.

[0020] Referring to FIGS. 1 to 3, an electric impact wrench (100) according to an embodiment of the present invention comprises: an electric motor (110) mounted within a main body housing (102) and including a drive shaft capable of outputting power; a drive unit (120) including a gear set coupled to the drive shaft of the electric motor (110) and linked to the electric motor (110); a hammer unit (130) connected to the drive unit (120); a handle housing (104) integrally connected to the main body housing (102) and manufactured in a handle shape in the lower direction of the main body housing (102); a battery unit (150) mounted at the bottom of the handle housing (104); an operating switch (140) installed at a predetermined position on the handle housing (104) for user operation regarding whether the electric motor (110) is operated; and an operating switch (145) for setting a target torque value. It may be implemented by including a motor driver (162) that is mounted within the handle housing (104), receives power from the battery unit (150), and transmits a driving signal to the electric motor (110) according to user operation of the operating switch (140), and a control unit (160) that performs a shut-off process to forcibly stop the driving of the electric motor (110) when the torque value transmitted to the bolting work object through the hammer unit (130) reaches the preset target torque value.

[0021] According to an embodiment of the present invention, the hammer unit (130) may be a two-hammer type. In addition, the battery unit (150) may be a rechargeable battery.

[0023] In one embodiment, the control unit (160) can calculate a unit torque value corresponding to a single strike operation by the hammer unit (130) according to a driving signal transmitted to the electric motor (110) through the motor driver (162) when the target torque value required for bolting fastening or bolting unfastening operation on the bolting work target is set by the operation switch (145).

[0024] Accordingly, the control unit (160) can calculate the number of target hits required to reach the target torque value using the calculated unit torque value, or calculate the unit time required for one hit operation to calculate the target hit maintenance time required to achieve the number of target hits.

[0026] Additionally, the control unit (160) may include a current measuring unit (164) that measures the current on the motor power supply line supplied from the battery unit (150) to the electric motor (110) according to a driving signal to be transmitted to the electric motor (110).

[0027] Accordingly, the control unit (160) receives a switch operation signal according to user operation regarding the operation switch (140), and at the time the switch operation signal is received, the drive signal is transmitted to the electric motor (110) through the motor driver (162), and at the same time, the operation of the current measuring unit (164) is activated from the time the switch operation signal is received to monitor the current on the motor power supply line.

[0029] Accordingly, the control unit (160) can determine that the point in time when the current value measured by the current measuring unit (164) is greater than a preset deviation by detecting whether the difference between the current value measured by the current measuring unit (164) when the hammer unit (130) is in a no-load state, where the hammer unit (130) is not being applied to the bolting work target, and the current value measured by the current measuring unit (164) when the hammer unit (130) is in a load state, where the hammer unit (130) is being directly applied to the bolting work target, is greater than a preset deviation, while the hammer unit (130) is in a no-load state during the hammering work during the hammering work during the hammering work during the hammering work during the hammering work, according to the switch operation signal according to the operation switch (140), is the point in time when the current value exceeds the deviation. This is because the no-load state and the load state can be distinguished by utilizing the fact that the current value in the no-load state and the current value in the load state have a difference between current values ​​greater than a predetermined deviation.

[0031] Accordingly, the control unit (160) can control the torque value transmitted to the bolting work target through the hammer unit to accurately reach the target torque value by maintaining the motor driving operation through the electric motor for the calculated target number of hits or the calculated target hit maintenance time based on the point in time when the load state is entered, and then executing a shut-off process to forcibly release the motor driving operation.

[0033] At this time, the control unit (160) can control the motor driving operation through the electric motor (110) to be maintained for the calculated target number of hits or the calculated target hit maintenance time, even when the switch operation signal through the operation switch (140) is released.

[0034] In addition, at this time, the control unit (160) can execute a shut-off process to forcibly release the motor driving operation through the electric motor (110) after the motor driving operation is maintained for the calculated target number of hits or the calculated target hit maintenance time, even when the switch operation signal through the operation switch (140) is maintained.

[0036] Referring to FIG. 4, a shut-off processing method according to the prior art is schematically illustrated. That is, the prior shut-off processing method focuses on safety control to prevent torque exceeding a set torque from being applied through an impact wrench.

[0037] On the other hand, according to the impact wrench according to the embodiment of the present invention described above, the time from when the actual load state is entered until the time when the target torque value is accumulated and reached is accurately calculated to enable precise torque control, and by executing a shut-off function based on the calculated value, the problem of inaccuracy in torque control, which was a disadvantage of conventional impact wrenches, can be resolved.

[0039] Although the present invention has been described above with reference to embodiments thereof, those skilled in the art will readily understand that various modifications and changes can be made to the present invention without departing from the spirit and scope of the invention as described in the following claims.

[0041] The present invention was filed as a result of the research and development project [R&D] Platform R&D, with the Korea Institute of Construction & Living Environment as the lead organization, under the project name "Technology Development for Fostering Leading Companies in Root Industries" and the project name "Development of a Reaction-Free High-Precision Rechargeable Battery Type 350 N.m Class Impact Torque Wrench."

Claims

Claim 1 As an electric impact wrench, the device comprises: an electric motor mounted within a main body housing and including a drive shaft capable of outputting power; a drive unit including a gear set coupled to the drive shaft of the electric motor and linked to the electric motor; a hammer unit connected to the drive unit; a handle housing integrally connected to the main body housing and manufactured in a handle shape in the lower direction of the main body housing; a battery unit mounted at the bottom of the handle housing; an operating switch installed at a predetermined position on the handle housing for user operation regarding whether the electric motor is operating; an operating switch for setting a target torque value; and a control unit including a motor driver mounted within the handle housing, supplied with power from the battery unit, and transmitting a drive signal to the electric motor according to user operation of the operating switch, and executing a shut-off process to forcibly stop the operation of the electric motor when the torque value transmitted to the bolting work object through the hammer unit reaches a preset target torque value.An electric torque wrench comprising, wherein the control unit, in accordance with a switch operation signal according to the operation switch, detects whether the difference between the current value measured by the current measuring unit when the striking action of the hammer unit is in a no-load state where the striking action of the hammer unit is not applied to the bolting work target, and the current value measured by the current measuring unit when the striking action of the hammer unit is in a load state where the striking action of the hammer unit is directly applied to the bolting work target, is greater than or equal to a preset deviation, thereby determining the point in time when the load state is entered when a difference greater than the deviation occurs, and based on the point in time when the load state is entered, maintains the motor driving operation through the electric motor for the calculated target number of strikes or the calculated target striking maintenance time, and then executes a shut-off process to forcibly release the motor driving operation, thereby controlling the torque value transmitted to the bolting work target through the hammer unit to accurately reach the target torque value. Claim 2 The electric impact wrench according to claim 1, wherein the control unit, when the target torque value required for bolting fastening or bolting unfastening work on the bolting work target is set by the operating switch, calculates a unit torque value corresponding to a single striking operation by the hammer unit according to a driving signal to be transmitted to the electric motor through the motor driver, calculates the number of target strikes required to reach the target torque value using the calculated unit torque value, or calculates the unit time required for the single striking operation to calculate the target striking holding time required to achieve the number of target strikes, and includes a current measuring unit that measures the current on the motor power supply line supplied from the battery unit to the electric motor according to the driving signal to be transmitted to the electric motor, and receives a switch operating signal according to user operation regarding the operating switch, and simultaneously causes the driving signal to be transmitted to the electric motor through the motor driver from the time the switch operating signal is received, and activates the operation of the current measuring unit from the time the switch operating signal is received to monitor the current on the motor power supply line. Electric impact wrench. Claim 3 An electric impact wrench according to claim 2, wherein the control unit controls the motor driving operation through the electric motor to be maintained for the calculated target number of hits or the calculated target hit maintenance time even when the switch operating signal through the operating switch is released, and executes a shut-off process to forcibly release the motor driving operation after the motor driving operation through the electric motor is maintained for the calculated target number of hits or the calculated target hit maintenance time even when the switch operating signal through the operating switch is maintained.

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