JP2004249423A - Motor-driven fastening tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor-driven fastening tool promoting heat radiation so that a temperature of an exothermic oil pulse mechanism part in work falls within an allowable range, easy in handling, and having no limitation in fastening capability and no restriction in continuous work. <P>SOLUTION: This motor-driven fastening tool has the oil pulse mechanism part for generating impact torque by being rotatably driven by an electric motor. A heat radiating projection is arranged on the outer periphery of the oil pulse mechanism part. The heat radiating projection is formed in a spiral shape, and an interval between the adjacent projections is set larger than clearance between an inner wall of an outer frame for housing the oil pulse mechanism part and the outer periphery of the heat radiating projection, and a slit parallel to the axis of the oil pulse mechanism part is also arranged. A wind window is arranged in the outer frame in response to both end positions of the heat radiating projection. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electric fastening tool provided with an oil pulse mechanism that is rotated and driven by an electric motor to generate an impact torque.
[0002]
[Prior art]
FIG. 6 shows an example of a conventional pneumatic fastening tool provided with an oil pulse mechanism. This pneumatic fastening tool has a housing 2, an air motor 8 rotated by compressed air in an outer frame 6, and a planetary gear mechanism 3 and an oil pulse mechanism 4 connected in front of the air motor 8. The oil pulse mechanism unit 4 fills and seals oil in a cavity formed in a liner 41 rotated by an air motor 8, and provides two blade insertion grooves 43 on an output shaft 42 coaxially fitted in the liner 41. The blade 44 is inserted into the blade insertion groove 43, and the blade 44 is constantly biased by the spring 47 in the outer peripheral direction of the output shaft 42 so as to abut the liner 41.
[0003]
The liner 41 is formed with four sealing portions projecting in a mountain shape on the inner peripheral surface (not shown), and among these, the tips of the blades 44 are in contact with each other to seal the inside of the cavity formed in the liner 41. The two seals are set so as to be rotated by 180 ° with respect to each other, and the other two seals contact the seal 46 formed on the outer peripheral surface of the output shaft 42 to seal the inside of the cavity formed in the liner 41. The seal portion is set such that the two seal portions are not symmetric with respect to each other, while being in the middle of being symmetric with each other by 180 °. Further, the output shaft 42 coaxially inserted into the liner 41 is set so that the two blades 44 are inserted into the blade insertion groove 43 and are rotated by 180 ° with respect to each other. The two seal portions protruding in a mountain shape are formed in the middle of the two blades 44 to be rotated by 180 ° so that they are not symmetrically rotated by 180 °, respectively, and the two seal portions formed in the liner 41 are formed. Is set so as to seal the cavity formed in the liner 41 in contact with the seal portion of the liner 41. Accordingly, when the liner 41 is rotationally driven by the air motor 8, when the seal portion of the liner 41 matches the tip of the blade 44 of the output shaft 42 and the seal portion of the liner 41 matches the seal portion of the output shaft 42, The cavity formed in the liner 41 is divided into four chambers, a high-pressure chamber and a low-pressure chamber, and generates one intermittent impact torque on the output shaft 42 for one rotation relative to the output shaft 42 of the liner 41. Can be. Also, when the air motor 8 is rotated in the reverse direction, one intermittent impact torque can be generated on the output shaft 42 for one rotation of the liner 41 relative to the output shaft 42 (for example, see Patent Document 1). reference.).
[0004]
An oil pulse mechanism using this method has been conventionally used as a low noise type because there is no collision between metals.
[0005]
The fastening tool by the oil pulse mechanism 4 generates friction because the oil is pushed out of the high-pressure chamber into the low-pressure chamber when the oil is compressed, and friction occurs when the blade 44 slides on the liner 41. Due to the heat generated by these, the temperature of the oil inside rises, the viscosity of the oil changes, and the output fluctuates. In the worst case, there is a problem that oil leaks due to a pressure increase in the oil pulse mechanism 4 due to heat generation.
[0006]
In the pneumatic fastening tool using the air motor 8, compressed air for rotating the air motor 8 is used, and the exhaust gas after the rotation of the air motor 8 flows to the outer periphery of the oil pulse mechanism 4. The compressed air is adiabatic-expanded and therefore cold, and the cold air forcedly cools the oil pulse mechanism 4 to solve the problem of heat generation. However, pneumatic fastening tools are inconvenient to handle because they require a compressor and an air hose.
[0007]
Although the electric fastening tool is easy to handle, there is no cold air as in the pneumatic fastening tool, and the oil pulse mechanism 4 cannot be forcibly cooled. Also, when a fan 12 is attached to the rotor 11 of the electric motor 1 and the wind generated by the fan 12 is directed to the oil pulse mechanism 4 and cooling is attempted, the wind is generated by the electric motor 1 due to the heat generated by the electric motor 1. Since such a cold wind does not occur, the oil pulse mechanism section 4 cannot be forcibly cooled only by the fan wind.
[0008]
As described above, the electric fastening tool cannot eliminate the heat generation, so that it is necessary to limit the tightening ability and restrict the continuous work so that the heat generation falls within the allowable temperature range of the oil pulse mechanism 4.
[Patent Document 1]
Japanese Utility Model Publication No. 4-51988 [0009]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to promote the heat radiation so that the temperature of the oil pulse mechanism that generates heat during work falls within an allowable range, to limit the fastening capacity, and to facilitate handling without restrictions on continuous work. It is to provide a simple electric fastening tool.
[0010]
[Means for Solving the Problems]
According to the present invention, in a motor-driven fastening tool provided with an oil pulse mechanism that is rotated and driven by an electric motor to generate an impact torque, a radiation projection is provided on an outer periphery of the oil pulse mechanism.
[0011]
The projections for heat dissipation are formed in a spiral shape, and the interval between adjacent projections is set to be larger than the clearance between the inner wall of the outer frame that houses the oil pulse mechanism and the outer periphery of the projections for heat dissipation. A slit parallel to the axis of the section is provided.
[0012]
Further, a wind window is provided on the outer frame in accordance with the positions of both ends of the heat radiation projection.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention will be described below with reference to the embodiments shown in FIGS. FIG. 1 is a sectional view of a main part of an electric fastening tool according to the present invention.
[0014]
In the schematic structure, an electric motor 1, a planetary gear mechanism 3, an oil pulse mechanism 4, a heat radiating protrusion 5, and an outer frame 6 are arranged in a housing 2 from the rear. The oil pulse mechanism 4 is of a known type using oil compression.
[0015]
The motor 1 is driven by a rechargeable battery (not shown) or a normal AC power supply (not shown), and the power of the motor 1 is transmitted to the planetary gear mechanism 3 via a pinion 31 connected to the tip of the motor 1. The oil pulse mechanism 4 is transmitted to drive the oil pulse mechanism 4. The oil pulse mechanism unit 4 fills and seals oil in a cavity formed in the liner 41 rotated by the electric motor 1, and forms two blade insertion grooves 43 on the output shaft 42 coaxially inserted in the liner 41. The blade 44 is inserted into the blade insertion groove 43, and the blade 44 is constantly urged in the outer peripheral direction of the output shaft 42 to come into contact with the liner 41, and the liner 41 is driven to rotate. When the seal formed on the inner peripheral surface of the oil shaft coincides with the seal 46 formed on the outer peripheral surface of the output shaft 42, pressure is generated in the oil pulse mechanism 4 and is generated as an impact torque from the output shaft 42, The tightening operation is performed via a tool (not shown).
[0016]
Due to the operation of the oil pulse mechanism 4, the oil in the oil pulse mechanism 4 generates heat due to friction when the oil is pushed from the high-pressure chamber to the low-pressure chamber and the sliding friction between the blades 44 and the liner 41. In order to dissipate this heat from the oil pulse mechanism 4, a heat radiation protrusion 5 is provided on the outer periphery of the oil pulse mechanism 4 so as to increase the external surface area as shown in FIG. The heat radiation projections 5 may be formed in a straight line or a circumferential direction in the axial direction. However, by setting them in a helical shape with a certain angle, the surface area can be maximized, and during the tightening operation, The heat radiation of the oil pulse mechanism 4 that generates heat can be promoted.
[0017]
The heat radiation projection 5 may be directly formed on the liner case 45 of the oil pulse mechanism 4 or may be formed as a separate metal part on the outer periphery of the oil pulse mechanism 4 (the outer periphery of the liner case 45). The same effect can be obtained by press fitting.
[0018]
FIG. 3 is an enlarged view of a portion A in FIG. The groove width B of the groove 51 formed by the heat radiating projection 5 is larger than the gap C formed by the inner wall of the outer frame 6 accommodating the oil pulse mechanism 4 and the outer shape of the heat radiating projection 5. Set. As described in the description of FIGS. 1 and 2, the projections 5 for heat radiation have a role of heat radiation, so that the gap C is preferably reduced as much as possible so that heat is easily transmitted to the outer frame 6. With this configuration, when the oil pulse mechanism 4 rotates, the inner wall of the outer frame 6 moves in the opposite direction, and the air in the groove 51 has air. A relative speed is generated by viscous force, and a flow is generated in a direction opposite to the rotational direction of the oil pulse mechanism 4. This air tends to flow on the lower side of the resistance, and the configuration in the outer frame 6 is larger in the groove width B than in the gap C. The air in the outer frame 6 is forcibly moved along the helical shape of the heat radiating projection 5 (as when the oil pulse mechanism 4 rotates clockwise). Therefore, a flow of air is formed in the outer shell 6 and heat can be radiated from the heat radiating projections 5. In addition, the heat in the outer frame 6 is agitated, so that heat can be efficiently transferred to the outer frame 6.
[0019]
FIG. 2 shows a clockwise rotation, and a leftward rotation causes the air flow to be in the opposite direction. Also, by changing the width and angle of the spiral groove 51 of the heat radiation projection 5, the direction in which air flows and the heat agitation force can be changed.
[0020]
FIG. 4 is an external view in which a slit 52 is provided on the heat radiation projection 5 in parallel with the axis of the oil pulse mechanism 4. While the oil pulse mechanism 4 is in operation, the flow of air can be formed in the outer frame 6 by the helical shape of the heat radiating projections 5 as described in FIG. 2, but this air follows the helical shape. By moving the inside of the groove portion 51 for a long time, that is, when the number of spiral shapes (the number of the heat radiation projections 5) is increased, the balance between the flow rate of air and the heat radiation from the heat radiation projections 5 is broken, and the heat quantity of the air is reduced. There is a possibility that the amount of heat transferred from the heat radiation projections 5 to the air is reduced due to saturation and the heat radiation effect is reduced. In addition, the air having the calorific value may act as a heat insulating material for blocking heat transfer to the outer frame 6. This can be estimated and prevented by calculating from the rotational speed during operation of the oil pulse mechanism 4, the average flow velocity and flow rate of air in the groove 51 obtained from the spiral shape, the surface area of the groove 51, and the amount of heat radiation. It is.
[0021]
As a method of preventing the increase in the number of helical strips (the number of heat radiation projections 5) and further increasing the heat radiation effect, as shown in FIG. By providing a slit 52 parallel to the core and dividing the spiral groove 51, the distance along the air flow (the length of the groove 51) is shortened, and the air is moved horizontally forward or backward through the slit 52. Then, there is a method of increasing the amount of heat transferred from the heat radiating projection 5 to the air by securing the air whose heat amount is not saturated. As shown by the arrow in FIG. 4 (when the oil pulse mechanism unit 4 rotates clockwise), it is possible to further promote the heat radiation by having the air move along the spiral shape and move the air horizontally through the slit 52.
[0022]
In the case of a continuous tightening operation, the heat generated by the oil pulse mechanism unit 4 increases, and may exceed the allowable heat amount of a method of transferring and radiating heat to the outer frame 6 or the air in the outer frame 6. The air flowing around the outer periphery of the oil pulse mechanism 4 becomes extremely hot, so that the oil pulse mechanism 4 cannot radiate heat.
[0023]
Therefore, as shown in FIG. 5, the outer frame 6 is provided with wind windows 7 serving as air intake and exhaust holes in accordance with the positions of both ends of the heat radiation projections 5. Since the gap C formed by the inner wall of the outer frame 6 accommodating the oil pulse mechanism 4 and the outer shape of the heat radiating protrusion 5 is minimized, the groove 51 having a low resistance when air passes therethrough is used. Flows through. For this reason, if the wind window 7 is provided at a position where the heat radiation projections 5 are largely deviated from the positions at both ends, the resistance of the gap C is high, and the flow of air is deteriorated. However, by providing the wind window 7 in the outer shell 6 at the positions of both ends of the heat radiating projection 5, the wind window 7 is opened above the groove 51, and when the heat radiating projection 5 passes through the wind window 7, The air pressure increases on the surface on the rotation direction side of the heat radiating projection 5 and the air pressure decreases on the opposite surface, and a pump action is generated, so that air can be taken into the groove 51 to form a flow of air.
[0024]
Therefore, it is configured that the outside air is always taken in while the oil pulse mechanism 4 is rotating, and the inside air that has become high temperature is exhausted, so that heat radiation can be further promoted.
[0025]
【The invention's effect】
According to the present invention, heat radiation projections are provided on the outer periphery of the oil pulse mechanism so as to increase the outer surface area, and the heat radiation projections are set to be helical to promote heat radiation of the oil pulse mechanism. The groove width of the heat radiation projection is set to be larger than the gap formed by the inner wall of the outer frame that houses the oil pulse mechanism and the outer shape of the heat radiation projection. By providing the slit horizontally with respect to the axis of the oil pulse mechanism, it is possible to form a flow of air in the outer frame and promote heat radiation.
[0026]
Further, the hot air is forcibly forced into the outer frame along the shape of the heat radiation projection through a wind window serving as an air intake / exhaust hole provided on the outer frame at positions of both ends of the heat radiation projection. By setting it to be moved and exhausted, it is possible to provide an easy-to-handle electric fastening tool that does not limit the fastening capacity, restrict continuous work, and the like.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an embodiment of the present invention.
FIG. 2 is a sectional view showing an embodiment of the present invention.
FIG. 3 is an enlarged view of a portion A in FIG. 1;
FIG. 4 is an external side view of an oil pulse mechanism showing an embodiment of the present invention.
FIG. 5 is a sectional view showing an embodiment of the present invention.
FIG. 6 is a sectional view showing a conventional pneumatic fastening tool provided with an oil pulse mechanism.
[Explanation of symbols]
1 is an electric motor, 2 is a housing, 3 is a planetary gear mechanism, 4 is an oil pulse mechanism, 5 is a heat radiation projection, 6 is an outer frame, 7 is a wind window, 8 is an air motor, 11 is a rotor, and 12 is a fan. 31 is a pinion, 41 is a liner, 42 is an output shaft, 43 is a blade insertion groove, 44 is a blade, 45 is a liner case, 46 is a seal portion, 47 is a spring, 51 is a groove, and 52 is a slit.

Claims (5)

What is claimed is: 1. An electric fastening tool comprising an oil pulse mechanism section that is driven to rotate by an electric motor to generate an impact torque, wherein a radiation projection is provided on an outer periphery of the oil pulse mechanism section. The electric fastening tool according to claim 1, wherein the heat-radiating projection has a spiral shape. The electric fastening tool according to claim 2, wherein an interval between the adjacent heat radiation protrusions is set to be larger than a clearance between an inner wall of an outer frame that houses the oil pulse mechanism and an outer periphery of the heat radiation protrusion. . 4. The electric fastening tool according to claim 3, wherein a slit parallel to the axis of the oil pulse mechanism is provided in the projection for heat radiation. The electric fastening tool according to claim 4, wherein wind windows are provided on the outer frame at positions of both ends of the heat radiation projection.

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