Electric fastening tool

Abstract

To provide an electric fastening tool capable of reliably suppressing a temperature rise of an electric motor and a temperature rise of a switching element that controls rotation of the electric motor.SOLUTION: An electric fastening tool 1 includes an electric motor M and an impact torque generating device P filled with working oil. The electric fastening tool transmits the rotational force of the electric motor M to the impact torque generating device P so as to generate impact torque. A motor shaft 14 of the electric motor M and a rotational force input portion 10 of the impact torque generating device P are mounted via a flange member 5 so as to rotate integrally and be thermally conductive to the flange member 5.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electric fastening tool. [Background technology]

[0002] BACKGROUND ART Conventionally, electric fastening tools have been used to fasten bolts and nuts with a predetermined torque (see, for example, Patent Documents 1 to 3).

[0003] However, in recent years, as electric tightening tools have become smaller and more powerful, when the electric tightening tool is used frequently, there has been a problem that the heat generated by the electric motor reduces work efficiency, shortens the life of the switching element, and in some cases may even lead to damage.

[0004] To address this problem, as disclosed in Patent Documents 1 and 2, cooling structures and other measures have been devised to prevent temperature rises in the electric motor and in the switching elements that control the rotation of the electric motor from becoming a practical problem. However, these conventional measures have been insufficient to resolve the above-mentioned problems, or have placed restrictions on the device configuration. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-58186 [Patent Document 2] Japanese Patent Application Publication No. 2016-221632 [Patent Document 3] Japanese Patent Application Publication No. 2018-144142 Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the problems associated with the conventional electric fastening tools described above, the present invention aims to provide an electric fastening tool that can reliably suppress temperature increases in the electric motor and in the switching elements that control the rotation of the electric motor. [Means for solving the problem]

[0007] In order to achieve the above object, the electric tightening tool of the present invention comprises an electric motor and an impact torque generating device filled with hydraulic oil, and is configured to transmit the rotational force of the electric motor to the impact torque generating device to generate impact torque, and is characterized in that the motor shaft of the electric motor and the rotational force input part of the impact torque generating device are attached to the flange member so as to rotate together and to be thermally conductive to the flange member via the flange member.

[0008] In this case, the flange member may have a cylindrical portion that covers the outer periphery of the impact torque generating device.

[0009] Also, cooling fins may be formed on the surface of the cylindrical portion.

[0010] Furthermore, the surface of the flange member may be coated with a heat-dissipating paint. [Effects of the Invention]

[0011] According to the electric fastening tool of the present invention, by reliably suppressing the temperature rise of the electric motor and the temperature rise of the switching element that controls the rotation of the electric motor, even if the electric fastening tool is used frequently, the heat generated by the electric motor does not reduce the work efficiency or shorten the life of the switching element. This eliminates the need for a large torque, and the increased moment of inertia generated when the electric motor rotates due to the mass of the flange member makes it possible to generate a stronger impact torque, which in turn makes it possible to make the electric fastening tool smaller and more powerful. [Brief explanation of the drawings]

[0012] [Figure 1] 1A and 1B are explanatory views showing an embodiment of an electric fastening tool of the present invention, in which (a) is an overall view showing the internal structure, and (b) is a partial view showing the internal structure of a modified example. [Figure 2] FIG. 2 is an explanatory diagram showing the internal structure of the vane air motor. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electric fastening tool according to the present invention will now be described with reference to the accompanying drawings.

[0014] FIG. 1 shows an embodiment of an electric fastening tool according to the present invention. This electric fastening tool 1 comprises an electric motor M and an impact torque generating device P filled with hydraulic oil, and transmits the rotational force of the electric motor M to the impact torque generating device P to generate impact torque. The motor shaft 14 of the electric motor M and the rotational force input part 10 of the impact torque generating device P are arranged to rotate together via a flange member 5 and are attached to the flange member 5 in a manner that allows thermal conduction.

[0015] The electric motor M may be an inner rotor motor, as used in this embodiment, in which a rotor 15 having a cylindrical magnet 11 attached to the inner periphery of a stator 3 equipped with a coil 2 rotates, or an outer rotor motor, in which a cylindrical rotor having a magnet attached to the inner periphery of the stator rotates on the outer periphery of the stator.

[0016] The rotation of the rotor 15 of the electric motor M is transmitted from a motor shaft 14 that rotates integrally with the rotor 15 to a flange member 5 that is supported via a bearing 20 on a housing 4 that accommodates the electric motor M.

[0017] The impact torque generating device P can suitably be a hydraulic device, such as that described in Patent Document 3, in which the rotational force of an electric motor M is transmitted to the impact torque generating device P, thereby rotating a liner 9 filled with hydraulic oil inside the impact torque generating device P, and when multiple sealing surfaces formed on the inner surface of the liner 9 match with the sealing surfaces and / or vanes formed on the outer surface of the main shaft 8, an impact torque is generated in the main shaft 8, thereby tightening or loosening bolts, nuts, etc. engaged with the tip of the main shaft 8.

[0018] The rotation of the motor shaft 14 of the electric motor M is transmitted to the liner upper cover, which is the rotational force input portion 10 of the impact torque generating device P, via the flange member 5, causing the liner 9 to rotate. The flange member 5 and the liner upper cover, which is the rotational force input portion 10 of the impact torque generating device P, are connected by a pin-shaped connecting portion 6 or a hexagonal connecting portion 13, so that they rotate integrally.

[0019] The flange member 5 may be disk-shaped or may have a cylindrical portion 5a that covers the outer periphery of the impact torque generating device P used in this embodiment. The flange member 5 can be made of a metal material such as iron or stainless steel.

[0020] In addition, by forming circumferential grooves at equal intervals on the outer peripheral surface of the cylindrical portion 5a of the flange member 5, A plurality of rib-like cooling fins 12 may be formed on the surface of the portion 5a to increase the surface area of ​​the flange member 5, or the surface of the flange member 5 may be coated with a heat-dissipating paint. This allows the heat dissipation performance of the flange member 5 to be improved.

[0021] Furthermore, a cooling fan 7 is provided to supply cooling air toward the cylindrical portion 5a of the flange member 5 that serves as a heat sink.

[0022] According to this electric fastening tool 1, the motor shaft 14 of the electric motor M and the rotational force input portion 10 of the impact torque generating device P are attached to the flange member 5 so as to rotate as a unit and to be thermally conductive thereto, so that the heat (thermal energy) generated by the electric motor M and the impact torque generating device P can be dissipated from the flange member 5. This reliably suppresses the temperature rise of the electric motor M, the switching elements that control the rotation of the electric motor M, and the impact torque generating device P. This prevents a decrease in work efficiency or a shortened lifespan of the switching elements due to the heat generated by the electric motor M and the impact torque generating device P, even when the electric fastening tool 1 is used frequently. This, combined with the fact that the increased moment of inertia generated when the electric motor M rotates due to the mass of the flange member 5 makes it possible to generate a stronger impact torque, makes it possible to make the electric fastening tool 1 smaller and more powerful.

[0023] Here, when an outer rotor motor is used for electric motor M, the rotor itself becomes the outer diameter of the motor, so the moment of inertia is larger than in an inner rotor motor in which rotor 15 is located inside stator 3, and a higher output torque can be obtained. However, because the stator and coil, which are the heat generating parts, are located inside the rotor, there is a problem that the heat dissipation performance is inferior to that of an inner rotor motor in which stator 3 with coil 2, which is the heat generating part, is located on the outer periphery of rotor 15 used in this embodiment. However, according to the present invention, this problem can be solved by improving heat dissipation performance.

[0024] Incidentally, vane air motors are widely used as power sources for this type of fastening tool, in addition to electric motors M. In the case of a vane air motor used in a pneumatic fastening tool, as shown in Figure 2, it is made up of an air motor rotor 17 incorporating several vanes 16 and a housing 18, and the output of the vane air motor is transmitted to the impact torque generator by connecting the impact torque generator to a coupling that is tightly fitted or integrated with the air motor rotor. This vane air motor receives compressed air from an air supply port 19, which enters the chamber separated by the vanes 16 and rotates the rotor. The vanes 16, which begin to rotate together with the rotor, are pressed against the inner wall of the housing 18 by centrifugal force, providing a reliable seal and ensuring stable operation. However, in pneumatic fastening tools, it is difficult to obtain sufficient motor output in the low rotation range immediately after starting, and if a flange member 5 with a large mass is attached, the torque required to start the vane air motor increases, which may prevent smooth fastening. On the other hand, the electric motor M has torque characteristics different from those of the vane air motor, and can output maximum torque immediately after the motor is started, and can transmit sufficient rotational force to the flange member 5 and the impact torque generating device P. From this, it can be said that an electric fastening tool using an electric motor M can fully utilize the effect of the moment of inertia added by the flange member 5, which has a large mass, immediately after starting, making it possible to perform high-torque fastening, and the combination of the electric motor M and the flange member 5 is highly compatible.

[0025] The electric tightening tool of the present invention has been described above based on its embodiments, but the present invention is not limited to the configuration described in the above embodiments, and the configuration can be changed as appropriate within the scope of the spirit of the present invention. [Industrial Applicability]

[0026] The electric fastening tool of the present invention has the characteristic of being able to reliably suppress the temperature rise of the electric motor and the temperature rise of the switching element that controls the rotation of the electric motor, and therefore can be widely used in electric fastening tools equipped with electric motors. [Explanation of symbols]

[0027] 1 Electric fastening tool 2 coils 3 Stator 4. Housing 5 Flange member 5a Cylindrical part 6 Joint part 7 Cooling fan 8 Main shaft 9 Liner 10 Rotational force input part (liner top cover) 11 Magnet 12 Cooling fins 13 Joint 14 motor shaft 15 rotors 16 vanes 17 Air motor rotor 18 Housing 19 Air supply port 20 Bearings M Electric motor P Impact torque generator

Claims

1. An electric fastening tool comprising an electric motor and an impact torque generating device filled with hydraulic oil, the rotational force of the electric motor being transmitted to the impact torque generating device to generate impact torque, characterized in that the motor shaft of the electric motor and the rotational force input part of the impact torque generating device are attached to the flange member so as to rotate integrally with each other and to be thermally conductive thereto.

2. 2. The electric fastening tool according to claim 1, wherein the flange member has a cylindrical portion that covers the outer periphery of the impact torque generating device.

3. 3. The electric fastening tool according to claim 2, wherein a cooling fin is formed on the surface of the cylindrical portion.

4. 4. The electric fastening tool according to claim 1, wherein a heat-dissipating paint is applied to the surface of the flange member.

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