JP6277634B2 - Portable cutting machine - Google Patents

Description

  The present invention relates to a portable cutting machine.

  As shown in FIGS. 5 and 6, the conventional portable cutting machine 101 includes a housing 102, a commutator motor 103 as a drive source, a rotational drive transmission mechanism 104 connected to the commutator motor 103, and this rotation. Mainly from a saw blade 105 rotated by a drive transmission mechanism 104, a handle 106 extended from the housing 102, and a base 107 that rotatably supports the housing 102 and abuts against a workpiece. It is configured.

  The housing 102 includes a motor housing 121 that houses the commutator motor 103, a gear case 122 that houses the rotational drive transmission mechanism 104, a saw cover 123 that covers the upper half of the outer peripheral surface of the saw blade 105, and a lower part of the outer periphery of the saw blade 105. It is comprised from the safety cover 28 which covers half. An opening is formed in the base 107, and the saw blade 105 protrudes downward from the opening.

  In the portable cutting machine 101, the commutator motor 103 is disposed on one side of the commutator motor 103 with the gear case 122 interposed therebetween, and the saw blade 105 and the saw cover 123 are disposed on the other side. The handle 106 extends upward from the housing 102. The handle 106 is provided with a switch 124 for turning on and off the energization of the commutator motor 103. A portable cutting machine configured in this way is described in Patent Document 1, for example.

JP 2002-346953 A

  The portable cutting machine described above is a tool for cutting, for example, wood, which is a member to be cut. The basic performance required for this type of tool is cutting performance and operability.

  For this reason, by adopting a brushless motor instead of the commutator motor of the portable cutting machine described above, the cutting performance is improved by increasing the efficiency of the motor, and the operability is improved by reducing the overall length of the motor and reducing the size and weight. Can be achieved.

  However, when a brushless motor is employed, the center of gravity of the portable cutting machine moves from the lower side of the handle to the saw blade side due to the reduction in size and weight by shortening the total length of the motor. Therefore, in the conventional portable cutting machine 101, when the operator grips the handle 106 and works, the portable cutting machine 101 is inclined toward the saw blade 105, and the operability during work is reduced. There was a problem to do.

  The present invention has been made to solve the above problems. An object of the present invention is to provide a portable cutting machine that can solve the problems that occur when adopting a brushless motor and can improve the operability during work.

  The present invention includes a housing, a brushless motor having an output shaft housed in the housing and extending to one side, a cutting blade that is rotationally driven by the output shaft of the brushless motor and cuts a workpiece. A base provided in the housing and having an opening for projecting the cutting blade; and a handle provided in the housing, wherein the handle is provided between the brushless motor and the cutting blade. In the portable cutting machine, a high specific gravity material is provided on the output shaft of the brushless motor on the side opposite to the cutting blade from the handle.

The high specific gravity material is preferably provided on the output shaft on the side opposite to the cutting blade from the rotor of the brushless motor, and the high specific gravity material is preferably formed of a sleeve attached to the output shaft.

A substrate for controlling the brushless motor is provided in the housing, a field effect transistor for controlling the brushless motor is provided on the substrate, and a blade for cooling the field effect transistor is provided on the sleeve. Preferably it is.

  It is preferable that the blades are formed radially on the outer periphery of the sleeve.

  It is preferable that a plurality of the field effect transistors are arranged so as to surround the blades of the sleeve.

  It is preferable that the center of gravity of the portable cutting machine is located below the handle.

  ADVANTAGE OF THE INVENTION According to this invention, the subject which arises when employ | adopting a brushless motor can be eliminated, and the portable cutting machine which can improve the operativity at the time of work can be provided.

It is a side view which shows the portable cutting machine which is embodiment of this invention. It is a principal part sectional front view of the portable cutting machine. It is the sectional view on the AA line of FIG. It is a partial sectional side view for demonstrating a gear mechanism. It is a side view which shows the conventional portable cutting machine. It is a principal part sectional front view of the portable cutting machine.

  Hereinafter, a portable cutting machine according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, a portable cutting machine 1 that is one of the electric tools is a portable cutting machine that includes a saw blade 2 formed of a circular saw that is a cutting blade.

  The portable cutting machine 1 is rotationally driven by a housing 3, a brushless motor 4 that is housed in the housing 3 and has an output shaft 5 that extends to one side, and an output shaft 5 of the brushless motor 4. A saw blade 2 for cutting the workpiece, a base portion 7 provided in the housing 3 and having an opening 6 for projecting the saw blade 2, and an operation handle 8 provided in the housing 3. And.

  The housing 3 has a base portion 7 that is placed in contact with a workpiece (not shown) during cutting work, and a circular saw body 9 is disposed on the opposite side of the lower surface 7a that is the workpiece contacting surface of the base portion 7. Is provided.

  The handle 8 is disposed between the brushless motor 4 and the saw blade 2 disposed in the left-right direction in the axial direction of the output shaft 5. The base portion 7 has a workpiece contact surface in which a lower surface 7a, which is one surface side, slidably contacts on a workpiece (not shown), and the base blade 7 projects the saw blade 2 toward the workpiece. For this purpose, a slit-like opening 6 is formed. In the vicinity of the front end of the base portion 7 in the cutting direction, there is provided a rotation support portion 11 that rotatably supports the circular saw body 9 with respect to the base portion 7 via a rotation pin 10. The moving support portion 11 is provided with a rotating pin 10 in parallel with a circular saw shaft 13 described later.

  The circular saw body 9 is constituted by a housing 3 that forms an outline of the circular saw body and a saw cover 12, and the saw blade 2 is disposed in the saw cover 12. The saw blade 2 corresponds to a working part. The housing 3 is located on one side of the saw blade 2.

  The housing 3 accommodates a brushless motor 4 for rotationally driving the saw blade 2 with the circular saw shaft 13 as a rotation axis. The housing 3 includes a motor housing 16 having an air inlet 14 formed on the side opposite to the saw blade and an air outlet 15 formed on the saw blade 2 side, and a power transmission mechanism for transmitting the rotation of the brushless motor 4 to the saw blade 2. 17 is housed, and is constituted by a gear case 18 positioned between the motor housing 16 and the saw cover 12.

  As shown in FIG. 4, the power transmission mechanism 17 includes a drive gear 19 provided on the output shaft 5 of the brushless motor 4, a driven gear 20 provided on the circular saw shaft 13 of the saw blade 2, and the drive gear 19 and the driven gear 19. The reduction gear mechanism 21 includes a first intermediate gear 21 a and a second intermediate gear 21 b provided between the gear 20 and the gear 20.

  The housing 3 is provided with a brake mechanism (not shown) for stopping the rotation of the brushless motor 4 in a short time when the power source is turned off by the operator. The housing 3 corresponds to the circular saw body 9 of the portable cutting machine 1. A rotor 22 is provided inside the motor housing 16, and the output shaft 5 of the rotor 22 forms the output shaft of the brushless motor 4. The output shaft 5 of the rotor 22 is rotatably supported in the housing 3 via bearings 23 and 24 in a state oriented in the left-right direction in FIG.

  One bearing 23 is attached to the gear case 18, and the other bearing 24 is attached to the circular saw body 9. A fan 26 is provided at an intermediate position of the output shaft 5 so as to be coaxially rotatable with respect to the output shaft 5 via a rotating member, for example, a one-way clutch 25 described later. The one-way clutch 25 causes the fan 26 to rotate with the rotation of the output shaft 5 driven by the brushless motor 4. Even if the output shaft 5 stops by stopping the driving of the brushless motor 4, the fan 26 rotates with inertial force. It has become.

  A handle 8 is provided at the top of the housing 3. The handle 8 is disposed between the brushless motor 4 and the saw blade 2. The handle 8 is provided with a trigger (trigger switch) 27 operated by an operator for driving the brushless motor 4. The saw cover 12 is integrally provided at one end in the longitudinal direction of the housing 3 so as to cover the upper half of the saw blade 2. The end of the saw cover 12 on the front side in the cutting direction is rotatably connected to the rotation pin 10 as described above, and the amount of projection of the saw blade 2 from the opening 6 of the base portion 7 is variable.

  Further, as shown in FIG. 1, between the base portion 7 and the circular saw body 9, a fixing release mechanism for fixing and releasing the circular saw body 9 with respect to the base portion 7 at a desired rotational position. A knob (not shown) is provided. That is, by loosening the knob and turning the circular saw body 9 with respect to the base portion 7 with the turning pin 10 of the turning support portion as a fulcrum, it is the workpiece contact surface of the base portion 7 through the opening 6. The protruding amount of the saw blade 2 protruding from the lower surface 7a to the workpiece side can be adjusted.

  When the saw blade 2 is set to a desired protrusion amount, a cutting operation can be performed with a desired protrusion amount by tightening a knob (not shown) constituting the fixing release mechanism. Further, the rotation support portion 11 has a mechanism for tilting the circular saw body 9 with respect to the base portion 7, that is, an inclination for tilting the circular saw body 9 in the width direction of the base portion 7 and fixing / releasing the tilt position. A mechanism (not shown) is provided.

  The circular saw body 9 is provided with a safety cover 28 that covers the lower half of the saw blade 2 when not in use so as to be rotatable around the circular saw shaft 13, and the safety cover 28 is rotated by a fingertip. A safety lever 29 for holding the position is provided. When cutting a workpiece (not shown), the safety cover 28 automatically contacts the workpiece and rotates to expose the lower half of the saw blade 2. Further, when it is necessary to move the saw blade 2 from above to below the workpiece such as a window cutting operation, the safety cover lever 29 may be hooked on the fingertip to maintain the safety cover 28 in the open state.

  An air passage 30 is formed between the housing 3 and the brushless motor 4 so as to be directed in the direction of the saw cover 12 as indicated by a broken arrow in FIG. Specifically, air flowing in from the air inlet 14 mainly flows along the side surface of the brushless motor 4 from the right side to the left side between the housing 3 and the side surface of the brushless motor 4, and An air passage 30 is formed so as to flow into the interior and flow from the right side to the left side in FIG. Air blown along the air passage 30 cools the substrate 32 having a control circuit such as the brushless motor 4 and a field effect transistor (FET) 31 controlled by the brushless motor 4, and air formed on the saw blade side of the housing 3. Air is discharged from the discharge port 15 to the outside of the housing 3.

  By the way, when the brushless motor 4 is employed, the center of gravity of the portable cutting machine 1 moves from the lower side of the handle 8 to the saw blade 2 side due to the reduction in size and weight by shortening the total length of the motor. Therefore, when the operator grips the handle 8 and works, the portable cutting machine 1 is inclined toward the saw blade 2 side, and there is a problem that the operability at the time of work is lowered. In order to solve this problem, as shown in FIGS. 2 to 3, the output shaft 5 of the brushless motor 4 is made of a material having a higher specific gravity than the output shaft 5 (for example, steel) so that the center of gravity is located below the handle 8. A high specific gravity material 33 is provided. The high specific gravity material 33 is preferably a cylindrical sleeve 33 </ b> A that is mounted on the outer periphery of the output shaft 5 so as not to rotate relative to the output shaft 5. The moment of inertia of the brushless motor 4 is increased by the weight of the sleeve 33A, so that stable rotation can be maintained.

  As described above, the housing 3 is provided with a substrate 32 having a field effect transistor (FET) 31 that constitutes a switching element for controlling the brushless motor 4, and the sleeve 33A is provided with the field effect transistor 31 and the substrate 32. The blade | wing 34 which generate | occur | produces the ventilation for actively cooling with ventilation is provided. The blades 34 are radially formed on the outer periphery of the sleeve 33A, and air is blown radially outward by the rotation to cool the field effect transistor 31 and the substrate 32 disposed around the blades 34. Yes.

  A plurality of field effect transistors 31 are arranged on the substrate 32 so as to surround the blades 34 of the sleeve 33A. The plurality of field effect transistors 31 are preferably arranged at intervals in the circumferential direction so that air flows between adjacent field effect transistors 31.

  The operation of the portable cutting machine 1 having the above configuration will be described. An operator holds the handle 8 of the portable cutting machine 1, places the lower surface 7a of the base portion 7 of the portable cutting machine 1 on the workpiece, places the portable cutting machine 1, and triggers 27 is operated. The brushless motor 4 is activated by the operation of the trigger 27, the rotational force of the output shaft 5 of the brushless motor 4 is decelerated by the power transmission mechanism 17 and transmitted to the saw blade 2, and the workpiece is cut by the rotation of the saw blade 2. be able to. At this time, since the fan 26 attached coaxially to the output shaft 5 is rotated by the rotation of the brushless motor 4, the fan 26 takes air into the motor housing 16 from the air inlet 14, and the brushless motor 4 and the field effect transistor 31 and the substrate 32 can be cooled.

  Next, the fan 26 in this Embodiment is demonstrated. The fan 26 is provided coaxially with the rotor 22 of the brushless motor 4 and capable of rotating integrally with or relative to the rotor 22 via the one-way clutch 25, and after the rotor 22 stops or the rotor. It is configured to rotate relative to the rotor 22 when the rotation of the 22 approaches a stop.

  Therefore, even after the brushless motor 4 is stopped, the fan 26 can be rotated by the inertial force of the fan 26 itself, so that the cooling capacity of the fan 26 can be improved, and the brushless motor 4 in the circular saw body 9 and the electrolysis can be improved. The effect transistor 31 and the substrate 32 can be effectively cooled.

  On the other hand, when the centrifugal force decreases or disappears (the rotor 22 is stopped, etc.), the engagement between the output shaft 5 and the fan 26 is released by the one-way clutch 25, and the fan 26 becomes a rotor (output shaft). On the other hand, the fan 26 can be rotated relatively and the rotation of the fan 26 can be continued even after the brushless motor 4 is stopped. Therefore, the cooling effect by the fan 26 and the effect of blowing off the waste can be maintained.

  The present invention is not limited to the embodiment described above, and various design changes can be made within the scope of the gist of the present invention. The brushless motor may be an outer rotor type. In the above embodiment, the high specific gravity material 33 is formed from a material having a higher specific gravity than the output shaft 5, but the high specific gravity material 33 may be formed from a material having the same specific gravity as the output shaft 5.

1 Portable cutting machine 2 Saw blade (cutting blade)
DESCRIPTION OF SYMBOLS 3 Housing 4 Brushless motor 5 Output shaft 6 Opening part 7 Base part 7a Lower surface 8 of a base part Handle 9 Circular saw body 10 Rotating pin 11 Rotating support part 12 Saw cover 13 Circular saw shaft 14 Air inlet 15 Air outlet 16 Motor Housing 17 Power transmission mechanism 18 Gear case 19 Drive gear 20 Driven gear 21 Reduction gear mechanism 21a First intermediate gear 21b Second intermediate gear 22 Rotors 23 and 24 Bearing 25 One-way clutch 26 Fan 27 Trigger 28 Safety cover 29 Safety lever 30 Wind Path 31 Field effect transistor 32 Substrate 33 High specific gravity material 33A Sleeve 34 Blade

Claims (8)

A housing ;
A brushless motor housed in the housing and having an output shaft and a rotor that rotates integrally with the output shaft ;
A bearing that rotatably supports the rotating shaft;
A cutting blade that is rotationally driven by the output shaft of the brushless motor and cuts the workpiece ;
A base portion having an opening formed for protruding the front SL cutting blade,
A handle provided on the housing ,
A portable cutting machine in which the handle is provided between the rotor and the cutting blade in the direction of the output shaft,
Said output shaft is Rutotomoni fan that rotates integrally with the output shaft is provided on the cutting blade side of the rotor, the bearing is provided on the counter-cutting blade side of the rotor,
The housing is provided with an air inlet that takes air into the housing by rotation of the fan, and an air outlet that discharges the air taken into the housing to the outside of the housing,
When the fan rotates, cooling air is generated from the air inlet through the brushless motor to the air outlet.
Wherein said output shaft between the bearing and the rotor in the direction of the output shaft, the steel a small than the outside diameter of the high specific gravity and said rotor than said output shaft is non-rotatably mounted, portable Cutting machine. In the direction of the front SL output shaft provided with the air inlet in counter-cutting blade side of the steel,
The portable cutting machine according to claim 1, wherein the cooling air passes through the brushless motor from the air inlet to the cutting blade side .   The portable cutting machine according to claim 2, wherein the steel material is a cylindrical sleeve attached to the output shaft. A substrate for controlling the brushless motor is provided so as to surround the output shaft on the side opposite to the cutting blade from the rotor in the direction of the output shaft ,
Before SL brushless motor and the substrate, the said fan in the direction of the output shaft is arranged between the air inlet, portable cutting machine according to claim 3. The substrate the electric field effect transistor that controls the brushless motor is provided, the blade for cooling by blowing the field effect transistor to said sleeve is provided, portable cutting machine according to claim 4.   The portable cutting machine according to claim 5, wherein the blades are radially formed on an outer periphery of the sleeve.   The portable cutting machine according to claim 5, wherein the field effect transistor is arranged so as to surround the blade of the sleeve.   The portable cutting machine according to any one of claims 1 to 7, wherein the center of gravity of the portable cutting machine is located below the handle.

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