JP4947490B2 - Electric tool - Google Patents

Description

  The present invention relates to an electric tool using a brushless motor.

Generally, in a power tool, a brushless motor that does not require electrical connection using a brush and a commutator to a rotor attached to a rotating shaft may be used as a means for realizing miniaturization of the power tool. However, when a brushless motor is driven, a relatively large power loss is generated as heat, which affects the operation of the motor and causes a reduction in efficiency and failure. For this reason, a cooling structure for a brushless motor has been proposed in conventional power tools. For example, as a conventional brushless motor cooling structure, as disclosed in Patent Document 1 below, an opening for sucking outside air into a motor housing and an opening for discharging cooling air inside the housing to the outside of the housing. Are formed in the housing so as to be spaced apart from each other in the direction of the rotation axis with the stator interposed therebetween, and air is introduced into the housing and the cooling air is caused to flow by rotating a fan or a fan integrally attached to the rotation shaft. Thus, a structure for cooling the brushless motor has been proposed.
JP 2006-315121 A

  By the way, in the above structure, it is necessary to rotate the fan in order to introduce air into the housing from the outside and cause the cooling air to flow. When the fan is integrally attached to the rotor or the rotation shaft, the fan rotates together with the rotor and the rotation shaft. However, if the fan and the rotor or the rotating shaft are not sufficiently fixed, even if the rotor or the rotating shaft rotates, the fan will run idle and air cannot be introduced from the outside, cooling the brushless motor. There is a problem that you can not.

  In view of such circumstances, an object of the present invention is to provide an electric tool that reliably prevents idling of a fan that cools a brushless motor.

  In order to achieve the above object, an invention according to claim 1 is an electric tool, comprising a housing, a brushless motor held in the housing, and a fan fixed to the brushless motor. The brushless motor is located on the inner peripheral surface side of the stator, and is concentric with the stator and rotates on the inner surface of the stator. A rotor arranged in a possible manner, and a rotating shaft that penetrates the rotor concentrically and rotates integrally with the rotor, the rotor having an axial direction from the one end surface to the other end surface of the rotor A plurality of extending through holes are formed in a uniform arrangement in the circumferential direction of the rotor, a magnet is inserted into the through holes, and the fan is concentric with the rotating shaft and has an end abutting against the other end surface of the rotor Shaft portion and blade portion extending from the shaft portion A notch is formed at a position corresponding to the through hole at the end of the shaft, and a first region between the magnet and the through hole, and the first region The adhesive is integrally disposed in the second region in the notch portion that follows.

  The invention according to claim 2 is characterized in that, in addition to the feature according to claim 1, a concave portion or a convex portion is formed on the other axial end surface of the rotor, and the end portion of the rotor is formed at the end of the shaft portion. Protrusions or depressions that engage with the recesses or protrusions are formed.

  According to the electric tool according to claim 1, since the adhesive is integrally disposed in the first region between the magnet and the through hole and the second region in the cutout portion following the first region, The adhesive in the first region secures the magnet to the rotor, and the adhesive in the second region secures the rotor and fan. Even when it is necessary to abut the other end surface of the rotor and the end surface of the fan shaft for the purpose of improving the positional accuracy, by accommodating the adhesive in the notch formed in the end surface of the fan shaft, An adhesive surface between the other end surface of the rotor and the end surface of the shaft portion of the fan can be formed, and the rotor and the fan can be fixed to each other. Therefore, the idling of the fan can be prevented. Specifically, first, an adhesive is applied to the through hole, and the magnet is inserted into the through hole from one end surface side, whereby the adhesive is disposed in the first region and fixes the magnet to the through hole. At least a part of the adhesive applied to the through hole is pushed out of the through hole and accommodated in the second region in the notch portion following the first region. Therefore, the trouble of supplying an adhesive separately between the other end surface of the rotor and the shaft portion of the fan can be omitted, and the manufacturing process can be shortened.

  According to the electric power tool of the second aspect, in addition to the effect of the electric power tool according to the first aspect, a concave portion or a convex portion is formed on the other axial end surface of the rotor, and the concave portion of the rotor is formed on the end surface of the shaft portion. Alternatively, since the protrusions or depressions that engage with the protrusions are formed, the rotor and fan can be easily and accurately aligned by engaging the depressions or protrusions with the protrusions or depressions. Idling can be more effectively prevented.

  Hereinafter, an electric power tool according to an embodiment of the present invention will be described with reference to FIGS. 1 to 10. FIG. 1 shows an impact driver 1 as an example of an electric power tool according to an embodiment of the present invention. First, a schematic configuration of the impact driver 1 will be described with reference to FIG.

  The impact driver 1 includes a housing 2 constituting an outer shell. The housing 2 includes a motor housing portion 21, a power transmission housing portion 22 formed continuously with the motor housing portion 21, the motor housing portion 21 and the power transmission. The handle housing portion 23 hangs down from the housing portion 22.

  The motor housing portion 21 has a cylindrical shape, and houses a brushless motor 30 serving as a driving source, a circuit board 40 that controls the brushless motor 30, and a fan 50. An air inflow hole 21a for injecting air from the outside of the housing 2 is formed at the rear of the motor housing portion 21, and an air exhaust hole 21b for discharging air to the outside is formed at the front of the motor housing portion 21. Has been. An air passage 21c is defined between the outer side of the brushless motor 30 and the inner peripheral surface 21A of the motor housing 21, and the air passage 21c communicates between the air inflow hole 21a and the air discharge hole 21b. .

  The power transmission housing part 22 accommodates the power transmission mechanism part 60. The power transmission mechanism section 60 includes a speed reduction mechanism section composed of a planetary gear 61 and a ring gear 62, and a spindle 63 and a hammer 65 that is disposed on the spindle 63 so as to be slidable back and forth and is given a striking force by a spring 64. This is a well-known configuration including an impact mechanism portion and an anvil 66 that can receive a rotary tool by a hammer 65 and can hold a tip tool (not shown). The power transmission mechanism 60 transmits the rotational force of the brushless motor 30 to the anvil 66 as a rotational impact force. The hammer 65 is provided with a protruding portion (not shown). Further, the anvil 66 is provided with a recess (not shown) corresponding to the protrusion of the hammer 65. When the brushless motor 30 is driven, the rotational force transmitted from the rotating shaft 35 of the brushless motor 30 is decelerated by the planetary gear 61 and the ring gear 62, and the rotational force is transmitted to the spindle 63 to start the screw tightening operation. When a load exceeding a predetermined level is not applied to the anvil 66, the hammer 65 and the anvil 66 rotate together to obtain a rotational force by fitting the convex portion of the hammer 65 and the concave portion of the anvil 66. On the other hand, when the anvil 66 is loaded with a predetermined load or more, the anvil 66 is locked and does not rotate, the convex portion of the hammer 65 and the concave portion of the anvil 66 are disengaged, and the hammer 65 moves forward and hits by the action of the spring 64. You will gain power.

  A lower end portion of the handle housing portion 23 is configured to be detachable from a battery pack case 71 that accommodates a battery pack 70 made of a lithium ion secondary battery, a nickel-cadmium secondary battery, or the like (not shown). The handle housing portion 23 is provided with a trigger switch 24 and accommodates wiring such as a lead wire 43 for supplying power from the battery pack 70 to the brushless motor 30 and a part of the motor drive circuit. When the battery pack case 71 is attached to the handle housing portion 23, the battery pack 70 and the motor drive circuit device are electrically connected via the trigger switch 24. The housing 2 will be described below with the anvil 66 side as the front, the air inflow hole side 21a as the rear, the motor housing portion 21 and the power transmission housing portion 22 as the upper side, and the battery pack case 71 side as the lower side.

  According to the impact driver 1 configured as described above, when the operator pulls the trigger switch 24 while holding the handle housing portion 23, the trigger switch 24 is turned on, and the driving force from the brushless motor 30 is transmitted. The screw 63 can be tightened by applying a rotational striking force to the tip tool mounted on the anvil 66.

  Next, with reference to FIG. 2 thru | or FIG. 10, the structure of the brushless motor 30 and the fan 50 of this Embodiment is demonstrated. The brushless motor 30 is a brushless motor including a stator 31 having a cylindrical outer shape, a coil 32, a rotor 33 disposed in an inner peripheral portion of the stator 31, and a rotating shaft 35 that rotates integrally with the rotor 33. is there. The rotor 33 and the rotating shaft 35 are disposed concentrically with the stator 31.

  The stator 31 includes a cylindrical portion and a plurality of teeth that protrude radially inward from the inner peripheral surface side of the cylindrical portion and extend in the axial direction of the cylindrical portion. An insulating member 81 and an insulating member 82 are attached to both ends of the stator 31 so as to cover the teeth. Specifically, an insulating member 81 is attached to the rear end of the stator 31, and an insulating member 82 is attached to the front end of the stator 31. The insulating member 81 and the insulating member 82 are held by the stator 31 by winding the coil 32 around the teeth covered with the insulating member 81 and the insulating member 82. The coil 32 is sequentially wound around a plurality of teeth and connected to a motor drive circuit, thereby forming a star-connected three-phase coil.

  The motor drive circuit will be described. The motor drive circuit includes a circuit board 40, is electrically connected to the coil 32, and has a function of driving the rotor 33 to rotate. The terminal of the coil 32 is electrically connected to the circuit board 40. The motor drive circuit includes an inverter circuit composed of a well-known bridge circuit for supplying a drive current to the coil 32 of the brushless motor 30, a control circuit composed of a CPU for controlling the inverter circuit, and the like. The circuit board 40 is formed with an inverter circuit provided with a switching element, and control circuits other than the inverter circuit are appropriately arranged on several boards (not shown).

  The circuit board 40 is fixed so that the front surface 40 </ b> A that is the surface of the circuit board 40 on the insulating member 81 side is in close contact with the insulating member 81. The front surface 40 </ b> A of the circuit board 40 includes a Hall element 41 for detecting the rotational position of the rotor 33, and a lead wire 43 that energizes the circuit board 40 is electrically connected. The rear surface 40B, which is the surface on the anti-insulating member 81 side of the circuit board 40, includes six FETs 42, which are the above-described switching elements for turning on and off the current flowing through the coil 32. The FET 42 is provided on the circuit board 40. The coil 32 is electrically connected via a wiring pattern. Further, the coil 32 terminal for the neutral point of each of the three-phase coils 32 of the stator 31 is electrically connected via the wiring pattern of the drive control circuit board so that the coil 32 is star-connected. It is made.

  The rotor 33 is press-fitted coaxially to a rotating shaft 35 supported at both ends so as to be rotatable by bearings supported by the motor housing portion 21, and rotates integrally with the rotating shaft 35. As shown in FIGS. 3 to 7, the rotor 33 has a through hole 33 a and a positioning hole 33 b that extend in the axial direction of the rotary shaft 35 from the rear end surface 33 </ b> A to the front end surface 33 </ b> B. Are formed in an even array of four in the circumferential direction. A permanent magnet member 37 is inserted into and fixed to the through hole 33a via an adhesive 91.

  A fan 50 is fixed to the front side of the rotating shaft 35 and on the air discharge hole 21 b side of the motor housing portion 21. When the brushless motor 30 is driven, the fan 50 rotates integrally with the rotary shaft 35, sucks external air from the air inflow hole 21a, and discharges it to the outside through the air passage 21c and the air discharge hole 21b. As shown in FIGS. 8 and 9, the fan 50 includes a shaft portion 51 that is concentric with the rotation shaft 35 and whose end surface 51 </ b> A contacts the other end surface 33 </ b> B of the rotor 33, and a blade portion that includes a plurality of blades extending from the shaft portion 51 52. On the end surface 51A of the shaft portion 51, a cutout portion 51a for accommodating the adhesive 91 is formed at a position corresponding to the through hole 33a of the rotor 33. As shown in FIG. 6 and FIG. 10, the adhesive 91 pushed out when the permanent magnet member 37 is inserted into the through hole 33 a of the rotor 33 is accommodated in the notch 51 a. Specifically, the adhesive 91 is first applied to the through hole 33a of the rotor 33, and the permanent magnet member 37 is inserted into the through hole 33a from the one end surface 33A side of the rotor 33, whereby the adhesive 91 is in the first region. The permanent magnet member 37 is fixed to the through hole 33a. At least a part of the adhesive 91 applied to the through-hole 33a is pushed out of the through-hole 33a and accommodated in the second region in the notch 51a following the first region. Further, a projection 51 </ b> B is provided on the end surface 51 </ b> A of the shaft portion 51 of the fan 50 at a position corresponding to the positioning hole 33 a of the rotor 33.

  According to such a configuration, the adhesive 91 is integrally disposed in the first region between the permanent magnet member 37 and the through hole 33a and the second region in the notch 51a following the first region. Therefore, the adhesive 91 in the first region fixes the permanent magnet member 37 to the rotor 33, and the adhesive 91 in the second region fixes the rotor 33 and the fan 50. Even when it is necessary to bring the other end surface 33B of the rotor 33 into contact with the end surface 51A of the shaft portion 51 of the fan 50 for the purpose of improving the positional accuracy, the notch portion 51a formed on the end surface 51A of the shaft portion 51 of the fan 50. Since the adhesive 91 is accommodated in this, an adhesive surface between the other end surface 33B of the rotor 33 and the end surface 51A of the shaft portion 51 of the fan 50 can be formed, and the rotor 33 and the fan 50 can be fixed to each other. . Therefore, idling of the fan 50 can be prevented. Further, after applying the adhesive 91 to the through-hole 33a formed in the rotor 33, the permanent magnet member 37 is inserted from the one end face 33A side, and at least a part of the adhesive 91 is pushed out from the through-hole 33a. By being accommodated in 51a, the trouble of separately supplying the adhesive 91 between the other end surface 33B of the rotor 33 and the shaft portion 51 of the fan 50 can be omitted, and the manufacturing process can be shortened. Further, since the permanent magnet member 37 is inserted from the one end face 33A side, at least a part of the adhesive 91 is pushed out from the other end face 33B side of the through hole 33a. Accordingly, the adhesive 91 is not pushed out from the one end surface 33A side of the through hole 33a, and there is no possibility that the adhesive 91 contacts the Hall element 41 provided on the front surface 40A of the circuit board 40.

  In addition, a positioning hole 33b is formed in the other end surface 33B of the rotor 33, and a projection 51B that engages with the positioning hole 33b of the rotor 33 is provided on the end surface 51A of the shaft portion 51 of the fan 50. By engaging the projection 51B with the protrusion 51B, the positioning of the rotor 33 and the fan 50 can be easily and accurately performed, and the idling of the fan 50 can be more effectively prevented.

  The electric power tool of the present invention is not limited to the above-described embodiment, and various changes can be made without departing from the scope of the present invention.

  In the above embodiment, as shown in FIGS. 5 and 6, the diameter of the shaft portion 51 of the fan 50 is smaller than the distance between the opposing through holes 33 a of the rotor 33, and the adhesive 91 is formed with the through holes 33 a. The rotor 33 and the fan 50 are not limited to this, although they are accommodated in the notch 51a through the other end surface 33B from between the permanent magnet member 37 and the permanent magnet member 37. For example, the distance between the opposing through holes 33a and the diameter of the shaft portion 51 of the fan 50 are the same, and the adhesive 91 is accommodated directly between the through hole 33a and the permanent magnet member 37 into the notch 51a. May be. Further, when the diameter of the shaft portion 51 of the fan 50 is made larger than the distance between the opposing through holes 33a, a concave portion is formed at a position facing the through holes 33a, and the adhesive 91 is permanently attached to the through holes 33a. You may accommodate in a recessed part directly from between magnet members 37.

  In the above-described embodiment, the positioning hole 33b of the rotor 33 is a through hole extending in the axial direction of the rotary shaft 35 from the one end surface 33A on the rear side to the other end surface 33B on the front side. It is not limited to. For example, instead of the positioning hole 33b, a concave portion that engages with the protrusion 51B formed on the end surface 51A of the shaft portion 51 of the fan 50 may be formed. Further, a convex portion is provided in place of the positioning hole 33b formed in the other end surface 33B of the rotor 33, and a recess that engages with the convex portion is formed in place of the protrusion 51B provided on the end surface 51A of the shaft portion 51 of the fan 50. May be.

  The power tool of the present invention can be suitably used for a tool that generates heat, such as an impact driver.

1 is an overall cross-sectional view of a power tool according to an embodiment of the present invention. It is a principal part enlarged view of FIG. It is a perspective view of a rotor and a fan of an electric power tool concerning an embodiment of the invention. It is the top view seen from arrow IV in FIG. It is sectional drawing along the VV line in FIG. It is sectional drawing along the VI-VI line in FIG. It is a perspective view which shows the rotor of the electric tool which concerns on embodiment of this invention. It is a perspective view which shows the fan of the electric tool which concerns on embodiment of this invention. It is the top view seen from arrow IX in FIG. It is sectional drawing along the XX line in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Impact driver 2 Housing 30 Brushless motor 31 Stator 32 Coil 33 Rotor 33A One end surface 33B Other end surface 33a Through hole 33b Positioning hole 35 Rotating shaft 37 Permanent magnet member 50 Fan 51 Shaft portion 51A End surface 51B Protrusion 51a Notch portion 52 Blade portion 91 Adhesion Agent

Claims (2)

A housing;
A brushless motor held in the housing;
A fan fixed to the brushless motor,
The brushless motor includes a cylindrical stator supported on the inner surface of the housing;
A coil wound around the stator;
A rotor located on the inner peripheral surface side of the stator, concentrically with the stator and rotatably disposed;
A rotating shaft that penetrates the rotor concentrically and rotates integrally with the rotor,
A plurality of through holes extending from one end surface of the rotor to the other end surface in the axial direction of the rotating shaft are formed in the rotor in a uniform arrangement in the circumferential direction of the rotor, and magnets are inserted into the through holes,
The fan has a shaft portion that is concentric with the rotating shaft and has an end portion that abuts against the other end surface of the rotor, and a blade portion that extends from the shaft portion. A notch is formed at a position corresponding to the through hole,
An electric power tool, wherein an adhesive is integrally disposed in a first region between the magnet and the through hole and a second region in the cutout portion following the first region.   A concave portion or a convex portion is formed on the other axial end surface of the rotor, and a projection or a recess engaging with the concave portion or the convex portion of the rotor is formed on the end portion of the shaft portion. The power tool according to claim 1.

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