JP2010120121A - Power tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power tool attaining high durability by increasing cooling efficiency of a power transmission mechanism including a motor, an oil pulse unit, and the like. <P>SOLUTION: The power tool has: the motor 3; the power transmission mechanism (4) for transmitting a rotational force of the motor; and a housing 6 for accommodating the motor 3 and the power transmission mechanism. The housing 6 has a cylindrical portion 6a and coaxially accommodates the motor and the power transmission mechanism at the cylindrical portion. A bearing retaining member 32 for retaining a bearing 10b and fixing the bearing 10b onto the housing 6a is provided between the power transmission mechanism and the motor. An air inlet for ventilating between the power transmission mechanism side and the motor side is provided in the bearing retaining member 32. The housing 6 has an air intake opening 31 and an air discharge opening therein. The outside air taken from the air intake opening 31 by a fan (17) is flowed so as to pass through the air inlet and discharged from the air discharge opening to the outside of the housing. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electric tool that is rotationally driven by a motor, and more particularly, to an electric tool that has improved durability and operability by improving a motor cooling mechanism.

  2. Description of the Related Art An oil pulse tool that generates a striking force using hydraulic pressure is known as an electric tool for tightening screws and bolts. Since the oil pulse tool does not collide with each other, it has a feature that the operation sound is lower than that of a mechanical impact tool. As such an oil pulse tool, for example, there is a technique disclosed in Patent Document 1, in which a motor is used as power for driving the oil pulse unit, and an output shaft of the motor is directly connected to the oil pulse unit. Since the temperature of the oil pulse unit increases with use, a fan is provided between the motor and the oil pulse unit (the front end side of the motor), and the motor is cooled by the fan. When a trigger switch for operating the oil pulse tool is pulled, a drive current is supplied to the motor. In Patent Document 1, a speed reducer is provided between a rotating shaft and an output shaft of a motor, and a small motor is driven at a high speed to ensure a necessary output torque, thereby reducing the size of the product.

JP 2005-40881 A

  The oil pulse tool uses hydraulic pressure to generate a striking force, and applies a striking force to a tip tool attached to the output shaft abruptly with a rotational force at a certain angle. At the time of hitting, the reaction force from the tip tool side is received, and this reaction force is applied to the support part of the reducer. Therefore, when a reducer is provided in an oil pulse tool, the reaction force increases and the impact is reduced. The vibration at the time increases. Therefore, in order to reduce the vibration at the time of hitting, it has been proposed to adopt a direct drive mechanism in which no speed reducer is provided between the rotating shaft of the motor and the oil pulse mechanism.

  However, in order to use the direct drive mechanism, the motor needs to be of a low speed and high torque type, which is larger than a high speed and low torque type using a general reduction gear. Furthermore, when a low-speed, high-torque motor is used, it is necessary to ensure sufficient strength of the bearing portion that supports the rotor. Furthermore, if the strength of the rotor support part is insufficient when a tool is used and a situation different from the intended purpose (dropping, etc.) occurs, the tool may be damaged by the inertia of the rotor. It is important that the support portion of the rotor has sufficient strength.

  After the impact in the oil pulse mechanism, the oil pal unit rotational speed is lowered by the reaction force from the tip tool side. However, in the brushless motor of the direct drive mechanism, the motor rotational speed is also lowered because there is no reduction gear. When a brushless DC motor is used, if the motor speed decreases due to the reaction force, a large current may be generated in the drive circuit, and the switching element may abnormally rise in temperature.

  The present invention has been made in view of the above background, and an object of the present invention is to provide an electric tool that has improved durability by improving the cooling efficiency of a power transmission mechanism such as a motor and an oil pulse unit.

  Another object of the present invention is to provide an electric tool that improves the strength of a bearing portion that supports a rotating shaft and realizes downsizing.

  Of the inventions disclosed in the present application, typical features will be described as follows.

  According to one aspect of the present invention, the motor includes a motor, a power transmission mechanism that is rotationally driven by the motor and transmits the rotational force of the motor, a housing that houses the motor and the power transmission mechanism, and a tip that is attached to the power transmission mechanism In a power tool that tightens a fastening member with a tool, a motor and a power transmission mechanism are housed inside the housing, and a single bearing for the rotating shaft of the motor is held between the power transmission mechanism and the motor, and the bearing is fixed to the housing. The bearing holding member for carrying out is provided, and the ventilation hole which ventilates between the power transmission mechanism side and the motor side was provided in this bearing holding member. An air intake port and an air discharge port are formed in the housing portion for housing the motor and the power transmission mechanism, and the outside air taken in from the air intake port by the fan flows through the ventilation port. It was configured to be discharged from the discharge port to the outside of the housing. That is, air can be moved between the power transmission mechanism side and the motor side by the ventilation port of the bearing holding member.

  According to another feature of the present invention, the fan is an electric fan provided behind the motor, and the electric fan is a centrifugal fan that is sucked in the axial direction and discharged in one direction in the circumferential direction. The bearing holding member is a metal member in which a circular through hole that accommodates the bearing is formed at the center, and the input of the motor rotation shaft and the power transmission mechanism is provided on the inner peripheral side of the bearing held in the through hole. The shafts are connected. A holding means for preventing the outer ring of the bearing from coming off in the axial direction is provided in the vicinity of the through hole of the bearing holding member.

  According to still another feature of the present invention, a plurality of ventilation holes are formed in the circumferential direction, and the number of ventilation holes is preferably a divisor (however, 2 or more) of the number of slots of the motor. Here, the divisor includes the same number as the number of slots (number divided by 1). The air intake is formed in the housing portion on the outer peripheral side of the power transmission mechanism, and the air discharge port is formed in the housing portion behind the motor. Furthermore, it is preferable to form the radial position on the inner peripheral side of the ventilation port so as to be located outside the radial position on the outer peripheral side of the rotor of the motor.

  According to the first aspect of the present invention, the bearing holding member for holding one bearing for the rotating shaft of the motor and fixing the bearing to the housing is provided between the power transmission mechanism and the motor, and the motor is mounted on the bearing holding member. Since the ventilation port for ventilating between the side and the power transmission mechanism side is provided, the cooling air can be passed from the power transmission mechanism side to the motor side or in the opposite direction, and the cooling effect can be enhanced. Further, since the bearing is held by the bearing holding member, the support portion of the rotor can be given strength and durability can be improved.

  According to the second aspect of the present invention, the air intake port and the air discharge port are formed in the housing, and the outside air taken in from the air intake port by the fan flows so as to pass through the ventilation port, and from the air discharge port to the outside of the housing. Since it is discharged, both the motor that easily generates heat and the power transmission mechanism can be effectively cooled.

  According to the invention of claim 3, the fan is an electric fan provided behind the motor, and can be controlled independently of the motor, so that an arbitrary air volume can be realized. Further, since the electric fan is a centrifugal fan that sucks in the axial direction and discharges it in one direction in the circumferential direction, a small fan can realize high blowing efficiency.

  According to the invention of claim 4, since the bearing holding member is a metal member in which a circular through hole for accommodating the bearing is formed in the center portion, the rigidity can be increased. In addition, since the rotating shaft of the motor and the input shaft of the power transmission mechanism are connected on the inner circumference side of the bearing held in the through hole, the impact force is dispersed by the bearing holding member even if an impact such as dropping is applied. Since it is transmitted, it is difficult to break and it is possible to improve durability.

  According to the invention of claim 5, since the holding means for preventing the outer ring of the bearing from coming off in the axial direction is provided in the vicinity of the through hole of the bearing holding member, an axial force is applied by an impact such as dropping. However, the bearing can be prevented from shifting.

  According to the sixth aspect of the present invention, since a plurality of ventilation holes are formed in the circumferential direction, the ventilation efficiency can be improved.

  According to the seventh aspect of the present invention, since the number of air vents is a divisor (however, 2 or more) of the number of slots in the motor, the cooling air can be effectively guided to the position of the motor winding.

  According to the eighth aspect of the present invention, the air intake is formed in the housing portion on the outer peripheral side of the power transmission mechanism and the air discharge port is formed in the housing portion on the rear side of the motor. Even when a mechanism that generates a large amount of heat is used, it can be effectively cooled.

  According to the ninth aspect of the present invention, since the radial position on the inner peripheral side of the ventilation port is located outside the radial position on the outer peripheral side of the rotor of the motor, the radial position is on the outer peripheral side of the winding of the stator that generates more heat. A lot of cooling air can be introduced, and the cooling effect can be further enhanced.

  According to the invention of claim 10, since the air movement between the power transmission mechanism side and the motor side is enabled by the ventilation port of the bearing holding member, the shape of the ventilation port is set to a desired location. It becomes possible to guide the cooling air.

  The above and other objects and novel features of the present invention will become apparent from the following description and drawings.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the present specification, an oil pulse tool will be used as an example of the electric tool, and the vertical and forward / backward directions will be described as directions shown in FIG.

  FIG. 1 is a cross-sectional view showing an entire oil pulse tool according to an embodiment of the present invention. The oil pulse tool 1 uses electric power supplied from the outside by a power cord 2, uses a motor 3 as a drive source, drives an oil pulse unit 4, which is a power transmission mechanism, by the motor 3, and is connected to the oil pulse unit 4. Further, by applying rotational force and impact force to the output shaft 5, the rotational impact force is transmitted continuously or intermittently to a tip tool (not shown) such as a socket bit to perform operations such as screw tightening and bolt tightening.

  The power supplied by the power cord 2 is a direct current power supply or an alternating current power supply such as AC 100V. In the case of alternating current, a rectifier (not shown) is provided in the oil pulse tool 1 and converted to direct current, and then sent to the motor drive circuit. It is done. The motor 3 is a brushless DC motor having a rotor 3b having a permanent magnet on the inner peripheral side and a stator having a winding 3c wound around an iron core 3a on the outer peripheral side, and includes two bearings 10a, 10b. The rotary shaft 11 is supported so as to be rotatable. The front bearing 10 b is a large-diameter bearing and is fixed in the cylindrical body portion 6 a of the housing 6 via the inner plate 32. The rear bearing 10a is a bearing having a smaller diameter than the front bearing 10b, and is fixed to a bearing holder 15 formed integrally with the body portion 6a. In the housing 6, the body portion 6a and the handle portion 6b are integrally manufactured by molding plastic or the like.

  A drive circuit board 7 for driving the motor 3 is disposed behind the motor 3. On the circuit board, an inverter circuit including a switching element 7a such as an FET (Field Effect Transistor) and a rotor 3b A position detection element such as a Hall IC for detecting the rotational position of the motor is mounted. A cooling fan unit 17 for cooling is provided near the inner rear end of the body portion 6a. The cooling fan unit 17 is an electric type that rotates independently of the motor 3, and can use a centrifugal fan that sucks from the vicinity of the front shaft and discharges it in one circumferential direction. Driven.

  The housing 6 has a handle portion 6b extending downward at a substantially right angle from the body portion 6a, and a trigger switch 8 is disposed in the vicinity of the attachment portion of the handle portion 6b. A switch circuit board 14 is provided inside the handle portion 6b, and a signal proportional to the amount by which the trigger switch 8 is pulled is transmitted to the motor control board 9a. A plurality of circuit boards 9 are disposed below the handle portion 6b, and include a motor control board 9a and a power supply circuit board 9b for a cooling fan.

  In the oil pulse unit 4 accommodated on the front side in the body portion 6a, the liner plate 23 as an input shaft is directly connected to the rotating shaft 11 of the motor 3, and the rotation of the motor 3 is directly transmitted without being decelerated. Therefore, on the inner side of the bearing 10 b, the connecting portion 23 a of the liner plate 23 is fitted into a hexagonal hole 11 f formed at the tip of the rotating shaft 11. As described above, the connecting portion between the liner plate 23 and the rotating shaft 11 is arranged at the same position in the axial direction as the inner plate 32, whereby the rigidity of the connecting portion can be increased.

  When the trigger switch 8 is pulled to start the motor 3, the rotation of the motor 3 is transmitted to the oil pulse unit 4. When the oil pulse unit 4 is filled with oil and no load is applied to the output shaft 5 or when the load is small, the oil pulse unit 4 outputs only in synchronism with the rotation of the motor 3 when the load is small. The shaft 5 rotates. When a strong load is applied to the output shaft 5, the rotation of the output shaft 5 stops, and only the liner on the outer peripheral side of the oil pulse unit 4 continues to rotate, and the oil pressure suddenly increases at one location per rotation. A large tightening torque (striking force) acts on the output shaft 5 to rotate the output shaft 5 with a large force. Thereafter, the same impact operation is repeated several times, and the striking force is intermittently transmitted repeatedly until the fastening target is tightened with the set torque.

  2 (1) is a cross-sectional view of the oil pulse unit 4 of FIG. 1, and FIG. 3 is a cross-sectional view of CC in FIG. It is sectional drawing shown. The oil pulse unit 4 is mainly composed of two parts: a drive part that rotates in synchronization with the motor 3 and an output part that rotates in synchronization with the output shaft 5 to which the tip tool is attached. The drive portion that rotates in synchronization with the motor 3 includes a liner plate 23 that is directly connected to the rotation shaft of the motor 3, a liner 21 that has a substantially cylindrical outer diameter that is fixed so as to extend forward on the outer peripheral side, and a liner. 21 includes a lower plate 26 fixed to the front inner peripheral side. The output portion that rotates in synchronization with the output shaft 5 includes a main shaft 24 and blades 25a and 25b (FIG. 3) attached to the main shaft 24 via springs.

  The main shaft 24 passes through the lower plate 26 and is held so as to be able to rotate in the liner 21. Between the liner 21 and the main shaft 24, hydraulic oil (oil) for generating torque is filled to form the liner 21. The oil is sealed by the liner plate 23 and the lower plate 26 attached to both ends of the plate. Between the lower plate 26 and the main shaft 24, and between the liner 21 and the liner plate 28, O-rings 27 and 28 are provided to ensure the airtightness between them. The liner 21 has a relief valve 22 for releasing the oil pressure from the high-pressure chamber to the low-pressure chamber, and can control the maximum pressure of the generated oil and adjust the tightening torque.

  Inside the liner 21 is formed a liner chamber having a cross section that forms approximately four regions as shown in FIG. Blades 25 a and 25 b are fitted and inserted into two opposed groove portions on the outer peripheral portion of the main shaft 24 via springs, and attached to the circumferential direction by the springs so that the blades 25 a and 25 b abut against the inner surface of the liner 21. Be forced. On the outer peripheral surface of the main shaft 24 between the blades 25a and 25b, two convex seal surfaces 26a and 26b that are axially extending are provided. Convex seal surfaces 27a and 27b and convex portions 28a and 28b are formed on the inner peripheral surface of the liner 21.

  When the seating surface of the tightening bolt is seated when the oil pulse tool 1 is tightened, a load is applied to the main shaft 24, the main shaft 24 and the blades 25a and 25b are almost stopped, and only the liner 21 continues to rotate. Along with the rotation of the liner 21 due to the rotation of the motor 3, an impact pulse is generated once per rotation. When this shock pulse is generated, the oil pulse tool 1 has a convex seal formed on the inner peripheral surface of the liner 21. The convex seal surface 26 a formed on the outer surface of the main shaft 24 is in contact with the surface 27 a. At the same time, the convex seal surface 27 b formed on the inner peripheral surface of the liner 21 and the convex seal surface 26 b formed on the outer peripheral surface of the main shaft 24 come into contact. As described above, the pair of convex seal surfaces formed on the inner peripheral surface of the liner 21 and the pair of convex seal surfaces formed on the outer peripheral surface of the main shaft 24 are in contact with each other. It is partitioned into a chamber H and two low pressure chambers L. Then, the main shaft 24 rotates to tighten the tightening bolt due to the pressure difference between the high pressure chamber H and the low pressure chamber L.

  Next, the operation procedure of the oil pulse unit 4 will be described. First, the motor 3 is rotated by pulling the trigger 8, and the liner 21 is rotated in synchronization therewith. (1) to (8) in FIG. 3 are views showing a state in which the liner 21 makes one rotation at a relative angle with respect to the main shaft 24. As described above, when no load is applied to the output shaft 5 or when the load is small, the main shaft 24 rotates almost in synchronization with the rotation of the motor 3 only by the resistance of oil. When a strong load is applied to the output shaft 5, the rotation of the main shaft 24 directly connected thereto stops and only the outer liner 21 continues to rotate.

  (1) in FIG. 3 is a diagram showing a positional relationship when a striking force is generated on the main shaft 24 by an impact pulse. The position shown in (1) is a position for sealing oil at one place per rotation. Here, the convex sealing surfaces 27a and 26a, the sealing surface 27b and the sealing surface 26b, the blade 25a and the convex portion 28a, and the blade 25b and the convex portion 28b contact each other in the entire axial direction of the main shaft 24, respectively. As a result, the inner space of the liner 21 is divided into four chambers of two high-pressure chambers and two low-pressure chambers.

  Here, the high pressure and the low pressure are pressures of oil existing inside. Further, when the liner 21 is rotated by the rotation of the motor 3, the volume of the high pressure chamber decreases, so that the oil is compressed and a high pressure is instantaneously generated. This high pressure pushes the blade 5 toward the low pressure chamber. As a result, a strong torque is generated on the main shaft 24 by momentarily acting through the upper and lower blades 25a and 25b. By forming this high-pressure chamber, a strong striking force that rotates the blades 25a, 25b in the clockwise direction in the drawing acts. The position shown in FIG. 3A is referred to as “blow position” in this specification.

  FIG. 3 (2) shows a state in which the liner 21 has rotated 45 degrees from the striking position. After passing the striking position shown in (1), the convex seal surfaces 27a and 26a, the convex seal surface 27b and the seal surface 26b, the blade 25a and the convex portion 28a, and the blade 25b and the convex portion 28b are in contact with each other. Is released, the space partitioned into the four chambers inside the liner 21 is released, and oil flows into the mutual space, so that no torque is generated, and the liner 21 further rotates as the motor 3 rotates.

  FIG. 3 (3) shows a state in which the liner 21 has rotated 90 degrees from the striking position. In this state, since the blades 25a and 25b are in contact with the convex seal surfaces 27a and 27b and do not protrude from the main shaft 24 and retreat to the inside in the radial direction, no torque is generated without being affected by the oil pressure. The liner 21 rotates as it is. FIG. 3 (4) shows a state in which the liner 21 has rotated 135 degrees from the striking position. In this state, the inner space of the liner 21 communicates and no oil pressure change occurs, so that no rotational torque is generated on the main shaft.

  FIG. 3 (5) shows a state in which the liner 21 has rotated 180 degrees from the striking position. At this position, the convex seal surfaces 27b and 26a and the convex seal surface 27b and the seal surface 26b come close to each other, but do not come into contact with each other. This is because the convex seal surfaces 26a and 26b formed on the main shaft 24 are not in a symmetrical position with respect to the axis of the main shaft. Similarly, the convex sealing surfaces 27a and 27b formed on the inner periphery of the liner 21 are not in a symmetrical position with respect to the axis of the main shaft. Therefore, torque is hardly generated at this position because it is hardly affected by oil. The generated torque is not zero because the oil filled inside is viscous, and when the convex seal surfaces 27b and 26a or the convex seal surfaces 27a and 26b face each other, it is slightly slightly. Since a high pressure chamber is formed, a slight rotational torque is generated unlike (2) to (4) and (6) to (8).

  The states (6) to (8) in FIG. 3 are substantially the same as (2) to (4), and no torque is generated in these states. Further rotation from the state of (8) returns to the state of (1) of FIG. 3, the convex sealing surfaces 27a and 26a, the sealing surface 27b and the sealing surface 26b, the blade 25a and the convex portion 28a, the blade 25b. And the convex portion 28b contact each other in the entire axial direction of the main shaft 24, and thereby the inner space of the liner 21 is partitioned into four chambers of two high-pressure chambers and two low-pressure chambers. Torque is generated.

  As described above, during the tightening operation, the oil is heated due to repeated pressurization and decompression of the viscous oil. Also, the rotation of the motor 3 is controlled at the time of striking, and in some cases, the rotation stops (locks) or reverses slightly, so an excessive current flows through the inverter circuit and the stator winding of the motor 3. The line 3c and the switching element 7a generate heat. As a countermeasure against this heat generation, a cooling fan unit 17 is provided as shown in FIG.

  Returning to FIG. 1, the cooling fan unit 17, the motor 3, and the oil pulse unit 4 are housed in the body portion 6 a of the housing 6, and the oil pulse unit 4, the motor 3, The cooling fan units 17 are installed in the order. Strictly speaking, the oil pulse unit 4 and the motor 3 are preferably arranged on the same axis, but the cooling fan unit 17 may not be completely on the same axis, and its central axis may be slightly shifted. The rotating shaft of the cooling fan unit may be arranged at an angle from the rotating shaft 11 of the motor 3.

  Since the oil in the oil pulse unit 4 has a large characteristic change due to heat and needs to be cooled most, it is efficient to cool the introduced outside air in this order. Accordingly, in the present embodiment, a plurality of air intakes 31 are formed on the side of the portion of the body portion 6a where the oil pulse unit 4 is provided, and the cooling fan unit 17 is driven to pass through the air intake 31. And the atmosphere was sucked from the outside. Although only one air intake 31 is shown in FIG. 1, the longitudinal direction of the air intake 31 is output as eight slit-like air intakes 31 in total, four on the right side of the body portion 6a and four on the left side. It is formed so as to be substantially parallel to the shaft 5. Note that the shape of the air inlet 31 has a relatively high degree of freedom, and the direction of the slit may be the circumferential direction of the body portion 6a, or any other shape.

  The outside air introduced from the air intake port 31 cools the oil pulse unit 4, passes through the vent hole 32 d of the inner plate 32, and flows to the motor 3 side. In the motor 3, it flows through the space between the rotor 3 d, the iron core 3 a, and the winding 3 c, flows backward, and cools the mounted electronic elements on the drive circuit board 7 provided behind the motor 3 in the axial direction and perpendicularly. . Thereafter, the air is sucked from the vicinity of the shaft in the cooling fan unit 17, is discharged in the circumferential direction from the discharge port 17 a by the fan, passes through an air discharge port described later formed in the body portion 6 a, and is discharged to the outside of the housing 6. .

  In the present embodiment, since the brushless motor of the direct drive mechanism is used, the number of rotations of the motor 3 at the time of striking is reduced, so that a large current flows through the winding 3c and the temperature of the switching element 7a is likely to rise. Therefore, by providing the drive circuit board 7 in the vicinity of the cooling fan unit 17, that is, on the rear side of the motor 3, the amount of cooling air in the vicinity of the switching element 7 a can be increased and the cooling efficiency can be improved. Improves durability.

  The cooling fan unit 17 is driven separately from the drive of the motor 3. Thereby, even when the rotation of the motor 3 is stopped, the oil pulse unit 4 and the motor 3 that have generated heat can be cooled. The cooling fan unit 17 is installed in the body portion 6 a of the housing 6 via the elastic body 30. Thereby, the vibration which the pulse unit part 4 causes at the time of impact is suppressed from being transmitted to the cooling fan unit 17, and the cooling fan unit 17 is prevented from being damaged. Further, when the cooling fan unit 17 is driven, noise accompanying rotational vibration is generated. However, since the cooling fan unit 17 is installed in the body portion 6a of the housing 6 via the elastic body 30, the vibration noise is suppressed. Is possible. By making the elastic body 30 into a foam material, it is possible to reduce the weight while enhancing the vibration control effect.

  The motor rotor 3 b is provided on the rotating shaft 11. FIG. 2B is an enlarged view of the rotating shaft 11 of FIG. 1, and the rotating shaft 11 is supported by a bearing 10 b on the side coupled to the oil pulse unit 4. The bearing 10b has a larger diameter than the bearing 10a, and the portion to which the bearing 10a is attached is a small diameter portion 11a whose diameter is slightly narrower than the shaft diameter portion 11b, and the portion to which the bearing 10b is attached. Is a large-diameter portion 11c whose diameter is slightly larger than that of the shaft-diameter portion 11b. A flange 11d whose diameter extends radially outward is formed in a part of the large-diameter portion 11c, and the bearing 10b is inserted into the large-diameter portion 11c from the front shaft end portion of the rotating shaft 11, and the rear end of the inner ring Is positioned so as to contact the flange 11d. Then, the bearing 35 b is fixed with respect to the rotating shaft 11 by mounting the tome 35 in the annular groove 11 e.

  An inner plate 32 is mounted on the outer ring side of the bearing 10b, and the front end of the outer ring is positioned so as to contact the flange 32c. The plate 33 is screwed with a screw 34, whereby the bearing 10b is fitted to the inner plate 32. Fix it. The inner plate 32 is a plate-like member having substantially the same thickness as the bearing 10b and is preferably made of a metal such as an aluminum alloy or a stainless alloy. Further, on both the inner ring and the outer ring side of the bearing 10b, a retaining is provided so that the bearing 10b does not move in the axial direction (front-rear direction) with respect to the inner plate 32. By holding the bearing 10b with a relatively large diameter in this way, the rotation axis of the tool from the rear or front of the tool body under a condition different from the original situation when using a tool such as a drop. Even when an abrupt load is generated on the side, the bearing 10b mainly receives the load due to the inertial force of the oil pulse unit 4 and the rotor 3b. Therefore, the strength of the fixed portion of the bearing 10a is the load applied during the rotation operation. It will be better if you endure only. Therefore, the thickness of the support portion (bearing holder 15) of the bearing 10a can be reduced, and the tool can be reduced in size. Furthermore, since the bearing 10a and the bearing holder 15 can be reduced in size, it is possible to increase the passage area of the cooling air flowing through the rear end of the motor 3, the amount of cooling air can be increased, and the cooling performance is improved.

  FIG. 4 is a perspective view showing the cooling fan unit 17 and the elastic body 30. The cooling fan unit 17 is provided with a suction port 17c for sucking air in the axial direction, and houses a rotating fan and a fan housing 17b for guiding the sucked and discharged air in a desired direction. A general-purpose blower fan having a discharge port 17a for discharging. The elastic body 30 is affixed to the cooling fan unit 17 with an adhesive, a double-sided tape, or the like, which reduces the vibration transmitted to the cooling fan unit 17 as well as an adhesive function for fixing the cooling fan unit 17 to the inner wall of the housing 6. Performs vibration control functions. Further, the elastic body 30a performs a sealing function for blocking the discharge port 17a from the space on the suction port 17c side.

  FIG. 5 is a cross-sectional view taken along line AA in FIG. 1 and shows a situation when the cooling fan unit 17 is installed inside the body portion 6 of the housing 6. The cooling fan unit 17 is fixed so that the discharge port 17 a faces the air discharge port 37 formed in the body portion 6 a of the housing 6. Although the cooling fan unit 17 has a mounting hole 17d for mounting, the cooling fan unit 17 is disposed in the space surrounded by the rear end portion of the housing 6, so that the double-sided tape is not firmly fixed with screws. It is sufficient to fix using a sealing material such as. However, it goes without saying that the screws may be fixed together.

  A buffer region 33 is provided between the discharge port 17 a and the air discharge port 37. As a result, the cross-sectional area of the air discharge port 37 can be made larger than that of the discharge port 17a. Even when a plurality of ribs are provided in the air discharge port 37 to prevent foreign matter from flowing in, the outflow from the air discharge port 37 can be prevented. Loss can be reduced. Further, by providing the seal-like elastic body 30a so as to surround the discharge port 17a and a part of the fan housing 17b, the cooling fan unit 17 is held by the elastic body 30a and flows into the buffer region 33 from the discharge port 17a. The cooling air can flow backward to the motor 3 side.

  FIG. 6 is a partial perspective view showing the internal shape of the right side of the rear end portion of the body portion 6a of the housing 6 to which the cooling fan unit 17 is attached. Here, the housing 6 can be divided into two in a vertically extending plane passing through the axial direction, and the right side indicates a side located on the right side when viewed by the operator when the operator holds the oil pulse tool with the right hand. A bearing holder 15 serving as a fixing portion for holding the bearing 10a is integrally formed at the rear end portion of the body portion 6a. A cooling fan unit 17 is fixed to the rear of the body holder 6a, and the discharge port 17 side of the cooling fan unit 17 is fixed. Ribs 16 are formed to separate the first space (buffer region 33). Four slit-like air discharge ports 37 extending in the vertical direction are formed behind the ribs. On the upper and lower sides of the bearing holder 15, two screw holes 13 for screwing to the left housing 6 are formed. Although not shown, the internal shape of the left side of the rear end portion of the body portion 6a is such that the rib 16 and the air discharge port 37 are not formed, but the screw hole 13 and the bearing holder 15 are formed.

  In FIG. 6, it can be understood that there is no opening in the rear end surface of the housing 6. This is because a blower fan whose discharge side is not the rear side but a side is used as the cooling fan unit 17. If another type of cooling fan is used, an air discharge port is provided on the rear end surface of the housing 6. Also good.

  Next, the shape of the inner plate 32 and the flow of the cooling air passing through the inner plate 32 will be described with reference to FIGS. 7 is a cross-sectional view taken along the line CC in FIG. The inner plate 32 includes a plurality of support columns 32c that connect between the annular inner peripheral ring 32a and the outer peripheral ring 32b, thereby forming a plurality of vent holes 32d through which cooling air passes. Here, as can be understood from the figure, the number and position of the support pillars 32c in the circumferential direction coincide with the positions of the gaps between the windings 3c of the motor 3. Accordingly, since the ventilation port 32d is arranged at a position facing the winding 3c of the motor 3, the air flowing from the oil pulse unit 4 side to the motor 3 side through the ventilation port 32d always hits the winding 3c. . Further, in the radial direction, the positions of the inner peripheral ring 32a and the outer peripheral ring 32b of the inner plate are set so as to substantially coincide with the inner peripheral side and outer peripheral side positions of the winding 3c of the motor 3, respectively.

  FIG. 8 is a cross-sectional view of the stator portion of the motor 3 in the B-B portion of FIG. 1, and a cross-sectional view of the stator 3 b portion of the motor 3. The stator has a winding 3c wound around an iron core 3a, and a slot (winding gap) 3d is provided between the windings 3c. As can be understood from this figure, in the present embodiment, the windings of the motor 3 are densely wound around the outer peripheral portion, and the number of turns of the inner peripheral portion is reduced.

  FIG. 9 is a cross-sectional view taken along a line DD in FIG. 7, showing a positional relationship between the inner plate 32 and the brushless motor stator portion, and a partial cross-sectional view showing a flow of air flowing from the inner plate 32 to the stator. is there. From this figure, the positional relationship between the column 32c of the inner plate 32 and the slot 3d can be well understood. As shown in FIG. 9, the cooling air taken in from the air intake 31 passes through the ventilation port 32d, flows into the space in which the motor 3 of the body portion 6a is disposed, and passes through the front portion of the winding 3c of the motor 3 Pass through to the slot 3d. When a brushless motor is used as the motor 3, since the heat generation of the winding 3c is large, the cooling air can be efficiently cooled by passing the front part of the winding 3c.

  FIG. 10 is a modification of the embodiment shown in FIGS. In this modification, the number of support posts 42c formed on the inner plate 42 is three, and the number of the six slots 3d is halved. Thus, the cooling efficiency can be improved without matching the number of slots 3d of the motor 3 with the number of ventilation openings 32d of the inner plate 32. However, when the number of slots 3d of the motor 3 and the number of vent holes 32d of the inner plate 32 are matched as shown in FIG. 7, the cooling efficiency can be improved most. In FIG. 10, the inner diameter of the vent hole 42d of the inner plate 42, that is, the inner peripheral ring 42a is set slightly larger than the outer diameter of the rotor 3b. As a result, the cooling air passing through the ventilation port 42d is likely to hit the outer peripheral side of the winding 3c of the rotor 3b, and the cooling efficiency can be further improved.

  FIG. 11 is a view for explaining the arrangement relationship between the oil pulse unit 4 and the handle portion in the present embodiment. The oil pulse mechanism is a low-noise hitting mechanism, and although the vibration at the time of hitting is small, the reaction force (displacement) at the time of hitting becomes large. Since the recoil is a circular motion around the hit source, the recoil increases as the distance from the hit source increases. In the present invention, by bringing the oil pulse unit 4 and the handle portion 6a close to each other in the front-rear direction, the grip portion becomes close to the impact source, and the reaction at the grip position is reduced. Specifically, in the oil pulse tool in which the front end portion of the oil pulse unit 4 is adjacent to the front end portion of the body portion 6 a of the housing 6, the handle portion 6 b of the housing 6 is provided substantially directly below the oil pulse unit 4. Therefore, the line 53 obtained by extending the longitudinal center line 52 of the handle portion 6b and the intersection 53 intersecting the center axis of the output shaft 5 are arranged in the arrangement of the oil pulse unit 4 when viewed in the axial direction (front-rear direction) of the output shaft 5. It exists in the position 51. Further, when the rear end position of the oil pulse unit 4 is compared with the most retracted position on the front side of the handle part, the rear end position of the oil pulse unit 4 is arranged rearward as indicated by an arrow range 54. . If comprised in this way, when tip tools, such as a socket, are attached to the output shaft 5, since the center-of-gravity position of the whole tool will be near a handle, the balance at the time of work will be good, and the operability will be improved. .

  As described above, in the electric power tool according to the present embodiment, the motor and the power transmission mechanism (oil pulse unit) can be cooled with high efficiency using an inexpensive general-purpose cooling fan, thereby improving durability. be able to. Further, by driving the fan asynchronously with the rotation of the motor, it is possible to improve the cooling efficiency of the switching element portion of the motor. Furthermore, the electric tool which can improve the intensity | strength of the bearing part which supports a rotor is realizable.

  As mentioned above, although demonstrated based on embodiment which shows this invention, this invention is not limited to the above-mentioned form, A various change is possible within the range which does not deviate from the meaning. For example, in the present embodiment, an example of an oil pulse tool using a brushless DC motor has been described as an example of an electric tool. However, the present invention is not limited to this, and the same applies to an arbitrary electric tool such as an electric drill or an electric glider. Applicable. Also, the type of motor to be used is not limited to a brushless DC motor, but may be a brushed DC motor or an AC motor.

It is sectional drawing which shows the whole oil pulse tool which concerns on embodiment of this invention. (1) is an enlarged sectional view of the oil pulse unit 4 in FIG. 1, and (2) is an enlarged sectional view of the rotating shaft 11 in FIG. It is sectional drawing in the axial direction and vertical surface of the oil pulse unit 4, Comprising: It is the figure which showed the motion of one rotation in the use condition of the oil pulse unit 4 in eight steps. It is the perspective view seen from the front of the cooling fan unit 17 of FIG. It is sectional drawing of the AA part of FIG. 1 of FIG. 1, and is the rear view which looked at the cooling fan unit 17 from back. FIG. 6 is a partial perspective view showing an internal shape of a rear end portion right side of a body portion 6a of the housing 6. FIG. 2 is a cross-sectional view taken along a line CC in FIG. 1 and shows a positional relationship between an inner plate 32 and a winding 3c of a motor 3. It is sectional drawing of the stator part of the motor 3 in the BB part of FIG. FIG. 8 is a cross-sectional view taken along a line DD in FIG. 7, showing a positional relationship between the inner plate 32 and the winding 3 c of the motor 3 and a flow of air flowing from the inner plate 32 toward the winding 3 c. . It is a figure which shows the inner plate 42 which concerns on the 2nd Embodiment of this invention, and is a figure which shows the shape in the cross section of CC part of FIG. It is a figure for demonstrating the arrangement | positioning relationship of the oil pulse unit 4 and handle | steering-wheel part of the oil pulse tool which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Oil pulse tool 2 Power cord 3 Motor 3a Iron core 3b (Motor) rotor 3c Coil 4 Oil pulse unit 5 Output shaft 6 Housing 6a (Housing) Body part 6b (Housing) Handle part 7 Drive circuit board 7a Switching Element 8 Trigger switch 9 Circuit board 9a Motor control board 9c Power supply circuit boards 10a, 10b, 10c Bearing
11 (motor) rotating shaft 11a narrow diameter part
11b Shaft diameter part 11c Large diameter part 11d Flange 11e Ring groove 11f Hexagonal hole 13 Screw boss 14 Switch circuit board
15 Bearing holder 16 Rib 17 Cooling fan unit 17a Discharge port 17b Fan housing 17c Suction port 17d Mounting hole 21 Liner 22 Relief valve 23 Liner plate 24 Main shaft 25a, 25b Blade 27, 28 O-ring 31 Air intake port 32, 42 Inner plate 32a, 42a Inner ring 32b, 42b (inner plate) Outer ring 32c, 42c (inner plate) strut
32d, 42d (Inner plate) Ventilation port 33 Plate 34 Screw 35 Tomewa 37 Air outlet

Claims (10)

A motor, a power transmission mechanism that is rotationally driven by the motor and transmits the rotational force of the motor, and a housing that houses the motor and the power transmission mechanism, and a fastening member is tightened by a tip tool attached to the power transmission mechanism In power tools,
Housing the motor and the power transmission mechanism in the housing;
A bearing holding member is provided between the power transmission mechanism and the motor to hold one bearing for the rotating shaft of the motor and to fix the bearing to the housing.
An electric tool characterized in that the bearing holding member is provided with a ventilation port for allowing ventilation between the power transmission mechanism side and the motor side. An air intake port and an air discharge port are formed in a portion of the housing that houses the motor and a portion that houses the power transmission mechanism,
A fan for generating an air flow is provided in the housing, and the outside air taken in by the fan from the air intake port flows through the ventilation port, and is discharged from the air discharge port to the outside of the housing. The electric tool according to claim 1, wherein   The said fan is an electric fan provided in the back of the said motor, This electric fan is a centrifugal fan which attracts | sucks to an axial direction and is discharged | emitted by one direction of the circumferential direction. Power tools.   The bearing holding member is a metal member in which a circular through hole that accommodates the bearing is formed at a central portion, and on the inner peripheral side of the bearing held in the through hole, the rotating shaft of the motor and the The power tool according to claim 2, wherein an input shaft of the power transmission mechanism is connected.   The electric tool according to claim 4, wherein holding means for preventing an outer ring of the bearing from coming off in an axial direction is provided in the vicinity of the through hole of the bearing holding member.   The power tool according to claim 4 or 5, wherein a plurality of the ventilation holes are formed in a circumferential direction.   The power tool according to claim 6, wherein the number of the ventilation openings is a divisor (however, two or more) of the number of slots of the motor.   The said air intake is formed in the housing part of the outer peripheral side of the said power transmission mechanism, and the said air discharge port is formed in the housing part of the back of the said motor. The electric tool as described in.   The power tool according to claim 8, wherein a radial position on the inner peripheral side of the ventilation port is formed to be located outside a radial position on the outer peripheral side of the rotor of the motor. The electric tool according to claim 1, wherein movement of air between the power transmission mechanism side and the motor side is enabled by the ventilation port of the bearing holding member.

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