JP4103626B2 - Electric fastening tool - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric fastening tool including an oil pulse mechanism that is rotationally driven by an electric motor to generate impact torque.
[0002]
[Prior art]
FIG. 6 shows an example of a pneumatic fastening tool provided with a conventional oil pulse mechanism. In this pneumatic fastening tool, an air motor 8 that is rotated by compressed air in a housing 2 and an outer frame 6, and a planetary gear mechanism portion 3 and an oil pulse mechanism portion 4 are connected in front of the air motor 8. The oil pulse mechanism 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 that is coaxially inserted in the liner 41. The blades 44 are fitted into the blade insertion grooves 43, and the blades 44 are always urged by the springs 47 in the outer peripheral direction of the output shaft 42 so as to come into contact with the liner 41.
[0003]
The liner 41 is formed with four seal portions (not shown) projecting in a mountain shape on the inner peripheral surface, and of these, the tip of the blade 44 contacts and seals the inside of the cavity formed in the liner 41. The two seal portions are set so as to rotate 180 ° relative to each other, and are in contact with the seal portion 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 so that the two seal portions are not subject to rotation by 180 ° between the two seal portions in the middle. Further, the output shaft 42 fitted coaxially in the liner 41 is set so that the two blades 44 are inserted into the blade insertion groove 43 and are mutually rotated by 180 °. Two seal portions protruding in a mountain shape are formed in the middle of the two blades 44 that are 180 ° rotation targets so as not to rotate 180 °, and two seal portions 41 are formed on the liner 41. The cavity formed in the liner 41 in contact with the seal portion is set to be sealed. Accordingly, when the liner 41 is rotated by the air motor 8, the seal portion of the liner 41 and the tip of the blade 44 of the output shaft 42 are matched, and the seal portion of the liner 41 and the seal portion of the output shaft 42 are matched. 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 do. Further, when the air motor 8 is reversed, one intermittent impact torque can be generated on the output shaft 42 for one rotation relative to the output shaft 42 of the liner 41 (for example, 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 from the high pressure chamber to the low pressure chamber when the oil is compressed, and frictional resistance is generated when the blade 44 slides with the liner 41. Due to the heat generated by these, the temperature of the internal oil rises, the viscosity of the oil changes and the output fluctuates. At worst, there is a problem that oil leaks due to an increase in pressure in the oil pulse mechanism 4 due to heat generation.
[0006]
In the pneumatic fastening tool using the air motor 8, compressed air that rotates the air motor 8 is used, and the exhaust gas after rotating the air motor 8 flows to the outer periphery of the oil pulse mechanism unit 4. Since the compressed air is adiabatically expanded, the compressed air is cold, and the oil pulse mechanism 4 is forcibly cooled with the cold air to solve the problem of heat generation. However, the pneumatic fastening tool is inconvenient to handle because it requires a compressor and an air hose.
[0007]
The electric fastening tool is easy to handle, but there is no cold air as in the pneumatic fastening tool, and the oil pulse mechanism 4 cannot be forcibly cooled. Further, even when a fan 12 is attached to the rotor 11 of the electric motor 1 and the wind generated by the fan 12 is applied to the oil pulse mechanism 4 to attempt cooling, the electric motor 1 generates heat and the wind is compressed air. Since it does not become such a cold wind, the oil pulse mechanism unit 4 cannot be forcibly cooled only by this fan wind.
[0008]
As described above, the electric fastening tool cannot eliminate heat generation, and it is necessary to limit the tightening capability and limit the continuous operation so that the heat generation is within the allowable temperature range of the oil pulse mechanism unit 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 heat dissipation so as to keep the temperature of the oil pulse mechanism that generates heat during work within an allowable range, and it is easy to handle without limitation of tightening ability and restriction of continuous work. Is to provide a simple electric fastening tool.
[0010]
[Means for Solving the Problems]
The present invention is characterized in that, in an electric fastening tool including an oil pulse mechanism portion that is rotationally driven by an electric motor and generates an impact torque, a heat dissipation protrusion is provided on the outer periphery of the oil pulse mechanism portion.
[0011]
The heat dissipating protrusion has a spiral shape, and the interval between adjacent protrusions 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 heat dissipating protrusion, and further, the oil pulse mechanism A slit parallel to the axis of the part is provided.
[0012]
The outer frame may be provided with wind windows in accordance with the positions of both ends of the heat dissipation protrusion.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the embodiments shown in FIGS. FIG. 1 is a cross-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 portion 3, an oil pulse mechanism portion 4, a heat dissipation protrusion 5, and an outer frame 6 are arranged in the housing 2 from the rear. The oil pulse mechanism unit 4 is of a known type utilizing 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. Then, the oil pulse mechanism 4 is transmitted. The oil pulse mechanism unit 4 fills and seals oil in a cavity formed in a liner 41 rotated by the electric motor 1, and has two blade insertion grooves 43 on an output shaft 42 that is coaxially inserted in the liner 41. The blade 41 is fitted and inserted into the blade insertion groove 43, and the blade 44 is constantly urged in the outer peripheral direction of the output shaft 42 so as to come into contact with the liner 41. By rotating the liner 41, the liner 41 is driven. When the seal portion formed on the inner peripheral surface of the shaft and the seal portion 46 formed on the outer peripheral surface of the output shaft 42 coincide with each other, pressure is generated in the oil pulse mechanism portion 4, and is generated as an impact torque from the output shaft 42. Tightening work is performed via a tool (not shown).
[0016]
Due to the operation of the oil pulse mechanism 4, heat is generated in the oil pulse mechanism 4 due to friction when oil is pushed out from the high pressure chamber to the low pressure chamber and sliding friction between the blades 44 and the liner 41. In order to dissipate this heat from the oil pulse mechanism 4, a heat dissipating protrusion 5 is provided on the outer periphery of the oil pulse mechanism 4 so as to increase the outer surface area as shown in FIG. 2. The heat-dissipating protrusions 5 may be formed in a straight line or a circumferential direction in the axial direction, but the surface area can be maximized by setting it in a spiral shape with a certain angle. The heat release of the oil pulse mechanism 4 that generates heat can be promoted.
[0017]
The heat-dissipating protrusions 5 may be directly machined and configured on the liner case 45 of the oil pulse mechanism unit 4, or the outer periphery of the oil pulse mechanism unit 4 (the outer periphery of the liner case 45) as a separate metal part. The same effect can be obtained by press fitting.
[0018]
FIG. 3 shows an enlarged view of part A of FIG. The groove width B of the groove 51 formed by the heat radiating protrusion 5 is larger than a gap C formed by the inner wall of the outer frame 6 that houses the oil pulse mechanism 4 and the outer shape of the heat radiating protrusion 5. Set. As described in the description of FIGS. 1 and 2, the heat dissipating protrusion 5 has a role of heat dissipation. Therefore, it is preferable to make the gap C as small as possible so that heat can be easily transferred 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 the viscous force, and a flow in a direction opposite to the rotation direction of the oil pulse mechanism unit 4 is generated. This air tends to flow in the direction of lower resistance, and the structure in the outer frame 6 has a larger groove width B than the gap C. Therefore, the air flows preferentially in the groove 51, and the arrow ( The air in the outer frame 6 is forcibly moved along the helical shape of the heat-dissipating protrusion 5 as in the case of the oil pulse mechanism 4 rotating clockwise. Accordingly, an air flow can be formed in the outer shell 6 to radiate heat from the heat radiating protrusion 5. Further, the heat in the outer frame 6 is agitated, and the heat can be efficiently transferred to the outer frame 6.
[0019]
FIG. 2 shows the case of right rotation, and the air flow is reversed in the case of left rotation. In addition, by changing the width and angle of the spiral groove 51 of the heat dissipating protrusion 5, the air flowing direction and the heat stirring force can be changed.
[0020]
FIG. 4 is an external view in which a slit 52 is provided in the heat dissipation projection 5 in parallel with the axis of the oil pulse mechanism 4. While the oil pulse mechanism 4 is in operation, it has been described in the description of FIG. 2 that the air flow can be formed in the outer frame 6 by the helical shape of the heat dissipation protrusion 5. If the groove 51 is moved for a long time, that is, if the number of spiral stripes (the number of the heat dissipation protrusions 5) is increased, the balance between the air flow rate and the heat dissipation from the heat dissipation protrusions 5 is lost, and the amount of heat of the air is reduced. The amount of heat transfer from the heat dissipation protrusion 5 to the air may be reduced and the heat dissipation effect may be reduced. In addition, the air having a saturated amount of heat may serve as a heat insulating material that blocks 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 the air in the groove 51 obtained from the spiral shape, the surface area of the groove 51 and the heat radiation amount. It is.
[0021]
As a method of further increasing the heat dissipation effect while preventing this when the number of spiral streaks (the number of heat dissipation protrusions 5) is increased, the heat dissipation protrusion 5 has a shaft of the oil pulse mechanism 4 as shown in FIG. A slit 52 is provided in parallel with the core, and the spiral groove 51 is divided to shorten the distance along the air flow (the length of the groove 51) and to move the air horizontally forward or backward through the slit 52. There is a method of improving the amount of heat transfer from the heat dissipating projection 5 to the air by securing air in which the amount of heat is not saturated. As shown by the arrows in FIG. 4 (when the oil pulse mechanism 4 rotates clockwise), heat can be further promoted by having both the movement of the air along the spiral shape and the horizontal movement of the air through the slit 52.
[0022]
When the continuous tightening operation is performed, heat generation of the oil pulse mechanism unit 4 increases, which may exceed the allowable heat amount of the method of transferring heat to the outer frame 6 or the air in the outer frame 6 to dissipate heat. The air flowing around the outer periphery of the oil pulse mechanism 4 becomes very hot, and the oil pulse mechanism 4 cannot radiate heat.
[0023]
Therefore, as shown in FIG. 5, the outer frame 6 is provided with air windows 7 serving as air intake and exhaust holes in accordance with the positions of both ends of the heat dissipation projection 5. Since the gap C constituted by the inner wall of the outer frame 6 that houses the oil pulse mechanism 4 and the outer shape of the heat-dissipating protrusion 5 is made as small as possible, the groove 51 has a lower resistance when air passes through it. Flowing. Therefore, if the wind window 7 is provided at a position without the heat-dissipating protrusion 5 greatly deviated from the positions of both ends, the resistance of the clearance C is high and the air flow is deteriorated. However, by providing the wind window 7 in the outer shell 6 so as to match the positions of the both ends of the heat dissipation projection 5, the shape is opened on the groove 51, and when the heat dissipation protrusion 5 passes through the wind window 7, The air pressure increases on the surface on the rotation direction side of the heat dissipating protrusion 5 and the air pressure decreases on the surface on the opposite side to generate a pump action, and air can be taken into the groove 51 to form an air flow.
[0024]
Therefore, it is configured so that outside air is always taken in while the oil pulse mechanism unit 4 is rotating, and the inside air that has reached a high temperature is discharged, and heat dissipation can be further promoted.
[0025]
【The invention's effect】
According to the present invention, the heat radiating protrusion is provided on the outer periphery of the oil pulse mechanism so as to increase the outer surface area, and the heat radiating protrusion is set to be spiral to promote heat dissipation of the oil pulse mechanism. And the groove width of the heat dissipating protrusion is set to be larger than the clearance formed by the inner wall of the outer frame that houses the oil pulse mechanism and the outer shape of the heat dissipating protrusion. By providing a slit horizontally with respect to the axis of the oil pulse mechanism, an air flow can be formed in the outer frame to promote heat dissipation.
[0026]
Further, air that has become hot from a wind window serving as an air intake / exhaust hole provided in the outer frame in accordance with the positions of both ends of the heat dissipation protrusion is forced to move inside the outer frame along the shape of the heat dissipation protrusion. By setting it to be moved and exhausted, it is possible to provide an electric fastening tool that is easy to handle and has no limitation on the tightening capability and no restriction on continuous work.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing an embodiment of the present invention.
FIG. 3 is an enlarged view of a portion A in FIG.
FIG. 4 is an external side view of an oil pulse mechanism showing an embodiment of the present invention.
FIG. 5 is a cross-sectional view showing an embodiment of the present invention.
FIG. 6 is a cross-sectional view showing a pneumatic fastening tool provided with a conventional 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 dissipation projection, 6 is an outer frame, 7 is an air 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 portion, and 52 is a slit.

Claims (4)

An electric motor;
An oil pulse mechanism that is rotationally driven by the electric motor to generate impact torque;
An outer frame for housing the oil pulse mechanism,
In the electric fastening tool with
A protrusion extending obliquely with respect to the rotation direction of the oil pulse mechanism is provided on the surface of the oil pulse mechanism, and a wind window is provided in the outer frame in accordance with the positions of both ends in the axial direction of the protrusion. An electric fastening tool characterized in that air flows along the protrusion when the mechanism portion rotates. The electric fastening tool according to claim 1, wherein a plurality of the protrusions are provided at intervals in the rotation direction. The electric fastening tool according to claim 1 or 2, wherein a plurality of the protrusions are provided at intervals in the axial direction. A plurality of the projections are provided at intervals in the axial direction and the rotation direction, and a slit formed between the projections adjacent to each other in the rotation direction is arranged in the axial direction, thereby forming a slit extending in the axial direction. The electric fastening tool according to claim 1, wherein:

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