Work Machine

Abstract

To improve cooling efficiency of a fan in a work machine having a rear cover and a main housing split into left and right parts.SOLUTION: A housing 10 of a work machine 1 comprises: a main housing 10 split into left and right parts; and a cup-shaped rear cover 60. Ventilation windows 18 for suctioning air are formed at left and right side surfaces of the main housing 10, and ventilation windows 64 (exhaust ports) for exhausting air exhausted from a fan to the outside are formed at the rear cover 60. A through hole 65 which penetrates to a protruding part 14 side of the main housing 10 in a downward direction is formed at the rear cover 60. Air is flowed into the protruding part 14 of the main housing 10 through the through hole 65, and air is exhausted to the outside through ventilation windows 19 formed at left and right sides of the protruding part 14. Addition of the ventilation windows 19 in this way increases a total area of the exhaust port in the downsized housing.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention provides an improvement in cooling performance in a work machine that uses a motor as a drive source to operate a tool tip. [Background technology]

[0002] A work machine that uses a removable battery pack as a power source to drive a motor and operate a tool tip to perform work is widely used. An example of such a work machine is an impact tool, which uses a battery pack as a power source to drive a motor. The motor of the work machine is held by a housing made of synthetic resin that can be divided into multiple parts. In the impact tool disclosed in Patent Document 1, the housing made of synthetic resin is formed by three members: a main housing that is divided into left and right parts, and a roughly cup-shaped rear cover that covers an opening at the rear of the main housing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-082252 A Summary of the Invention [Problem to be solved by the invention]

[0004] In portable working machines such as those described in Patent Document 1, there is a strong demand for miniaturization of the working machine, so the housing is designed to be as compact as possible, but as a result of promoting the miniaturization of the housing, a problem occurs in that the space for increasing the number of ventilation windows for improving cooling is limited. In addition, as the pursuit of miniaturization of the housing increases, the demand for improved output leads to an increase in motor output, making it increasingly important to ensure cooling performance.

[0005] The present invention has been made in view of the above background, and has an object to provide a work machine with improved cooling performance. Another object of the present invention is to provide a work machine that can prevent exhaust air from hitting the hands of an operator gripping a handle. [Means for solving the problem]

[0006] Representative features of the invention disclosed in this application are as follows. According to one aspect of the present invention, a tool holder includes a motor for driving a tool bit, a main housing for accommodating at least a portion of the motor, extending in the front-rear direction and having a body portion with an opening at the rear, a rear cover connected to the opening, and a tool holder for connecting the main housing to the body portion. Formed as part of R 、 In a work machine having a protrusion extending rearward from an opening, a fan driven by the rotation of a motor, a first intake section provided in a body section for taking in outside air into the body section by the fan, and a first exhaust section provided in a rear cover for discharging air taken in from the first intake section by the fan to cool the motor, the first exhaust section is provided on a side surface (outer peripheral surface) of the rear cover and a portion (e.g., a lower side surface) facing the protrusion. A second intake section is formed in the protrusion at a position facing the first exhaust section, and air discharged from the first exhaust section flows again into the main housing from the second intake section, and the inflowing air is discharged to the outside via the second exhaust section formed in the main housing. A handle section to be held by an operator is provided below the main housing, and the protrusion is provided on a lower portion of the rear cover.

[0007] According to another aspect of the present invention, , Li A third exhaust section for discharging air taken in from the first intake section by the fan to the outside is formed on the left and right side surfaces or the upper side surface of the cover at a position not facing the protruding section. The second exhaust section is provided on the protruding section. Furthermore, an operating section for a switch for starting the motor and a switching lever for switching the rotation direction of the motor are provided so as to be exposed to the outside from inside the main housing, and a part of the air taken in from the second intake section is configured to be discharged to the outside through a gap between the operating section and the main housing and / or a gap between the switching lever and the main housing.

[0008] According to yet another feature of the present invention, the second exhaust section is disposed above the handle section of the main housing, and air exhausted from the second exhaust section is discharged in a direction other than toward the hand of an operator holding the handle section. At least a portion of the outer surfaces of the main housing and the rear cover are formed of an elastomer, and the connection between the first exhaust section and the second intake section is sealed by the close contact between the elastomer on the main housing side and the elastomer on the rear cover side.

[0009] According to yet another feature of the present invention, a gap is provided between the rear cover and the protruding portion, and the air discharged from the first exhaust portion is discharged into the atmosphere through the gap. The gap is formed so as to open in the left / right direction or rearward. The upper surface of the protruding portion is Concave downwards concave Condition and Furthermore, a battery pack attachment portion to which a battery pack can be attached and detached is provided at the lower end of the handle portion, and the main housing is configured as a left and right split type and is configured to have a body portion, a handle portion, and a battery pack attachment portion. Effect of the Invention

[0010] According to the present invention, in a working machine in which a motor for driving a tool tip, a main housing having a cylindrical body, and a rear cover connected to the rear opening of the main housing and having a different structure from the main housing are combined, the first through hole of the rear cover is provided on a surface other than the left and right side surfaces of the rear cover, thereby making it possible to increase the area of ​​the exhaust port and the flow rate of cooling air more than before. In addition, a protrusion extending rearward from the rear opening of the main housing is formed below the rear cover, and an air passage is formed from the rear cover to the protrusion side, so that air is exhausted to the outside through the air window (fourth through hole, exhaust section) formed on the protrusion side of the main housing, thereby making it possible to further increase the amount of exhaust air from only the air window (second through hole) formed on both the left and right side surfaces of the rear cover. In addition, a flat space (gap) extending to both the left and right sides and rearward is provided between the first through hole of the rear cover and the protrusion of the main housing, and exhaust air is exhausted to the outside from the gap, making it possible to prevent the exhaust air from hitting the hands of the operator holding the handle. [Brief description of the drawings]

[0011] [Figure 1] 1 is a vertical sectional view of an impact tool 1 according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a partial side view of the impact tool 1 of FIG. [Diagram 3] FIG. 2 is an enlarged view of part A in FIG. [Figure 4] 1 is a partially enlarged view showing first to third modified examples of the embodiment of the present invention. [Diagram 5] FIG. 2 is a vertical sectional view of an impact tool 1A according to a second embodiment of the present invention. [Figure 6] 6 is a rear view of the body 11 of the impact tool 1A of FIG. 5. [Figure 7] FIG. 11 is a vertical sectional view of an impact tool 1B according to a third embodiment of the present invention. [Figure 8] 8 is a rear view of the body 11 of the impact tool 1B of FIG. 7. FIG. [Figure 9]13A and 13B are views of an impact tool 1C according to a first modified example of the third embodiment of the present invention, in which (A) is a vertical sectional view passing through the rotation axis A1, and (B) is a rear view. [Figure 10] 13A and 13B are views of an impact tool 1D according to a second modified example of the third embodiment of the present invention, in which (A) is a vertical sectional view passing through the rotation axis A1, and (B) is a rear view. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLES

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following drawings, an impact tool will be used as an example of a work machine, and the same parts will be denoted with the same reference numerals. In addition, in this specification, the front-rear, left-right, and up-down directions will be described as directions shown in the drawings.

[0013] FIG. 1 is a vertical cross-sectional view of an impact tool 1 according to an embodiment of the present invention. The impact tool 1 fastens a tip tool such as a bit (not shown) and is one type of work machine. The impact tool 1 uses a rechargeable battery pack 100 as a power source and a motor 20 as a drive source to drive a rotary impact mechanism, which converts the rotation of a rotating member into intermittent impact force in the rotational direction by the rotary impact mechanism, and drives an anvil 55 connected to the impact mechanism. The housing of the impact tool 1 is composed of a main housing 10 divided into left and right, a hammer case 3 connected to the front side of the main housing 10, and a rear cover (rear housing) 60 that covers the rear opening of the main housing 10.

[0014] The main housing 10 has a generally cylindrical body 11 extending in the front-rear direction, a handle 12 connected to the body 11 so as to form a generally T-shape in a side view, and a battery pack attachment portion 13 formed below the handle 12. The main housing 10 of this embodiment has a rear opening 11b (see FIG. 2 for the reference symbol) on the rear side in addition to a front opening 11a (see FIG. 2 for the reference symbol) of the cylindrical body 11, and the rear opening 11b is closed by a rear cover 60. A metal hammer case 3 is connected to the front opening 11a. The hammer case 3 is fixed so as to be sandwiched from the left and right directions by the split main housing 10. The outside of the hammer case 3 is covered by a synthetic resin cover 5, so that an operator cannot directly touch the metal part of the hammer case 5. The rear end side of the cover 5 is connected to the front opening 11a (see FIG. 2 for the reference symbol) of the main housing 10.

[0015] The handle portion 12 extends downward so as to be approximately perpendicular to the central axis (rotation axis A1) of the body portion 11, and an operator grips the handle portion 12 with one hand, as shown by a hand 110 with a dotted line. A trigger lever 6a is provided at the location where the index finger of the hand 110 would be positioned when gripping the handle portion 12. The trigger lever 6a is an operating part for a trigger switch 6 for controlling the on / off and rotation speed of the motor, and is normally located at the front as shown in Figure 1, and can be moved rearward from the state in Figure 1 by the hand 110. A forward / reverse switching lever 7 for switching the rotation direction of the motor is provided above the trigger lever 6a.

[0016] A battery pack attachment section 13 is formed on the lower side of the handle section 12 to attach the battery pack 100. The battery pack attachment section 13 is an expanded diameter section formed to expand in the radial direction (orthogonal direction) from the longitudinal central axis of the handle section 12. A control circuit board 34 for controlling the rotation of the motor 20 is mounted in the battery pack attachment section 13 of the main housing 10. The control circuit board 34 is mounted with various control elements (not shown) including a microcomputer for controlling the on / off, rotation direction, and rotation speed of the motor 20. The battery pack 100 contains a plurality of secondary batteries such as lithium ion batteries, and can be removed from the main housing 10 by moving the battery pack 100 forward while pressing the latch button 101 from the attached state shown in FIG. 1. The power source of the impact tool 1 of this embodiment is arbitrary, and it may be a commercial power source supplied via an AC power cable instead of the battery pack 100.

[0017] The split-type main housing 10 is made of synthetic resin, and one side (left side) is formed with multiple screw bosses 16a-16h for screwing, and the other side (right side) of the main housing 10 (not shown) is formed with screw holes. The left and right main housings 10 are screwed together with the hammer case 3 sandwiched between them on the front side, and then an integrated rear cover 60 is attached to the main housing 10 with multiple screws (not visible in the figure). The rear cover 60 is cup-shaped, with an opening surface 63 (see FIG. 2 for the symbol) formed on the front side, and a rear wall portion 62 forming the bottom surface of the cup formed on the rear side.

[0018] The motor 20, which is a drive source, is accommodated inside the space defined by the body 11 and the rear cover 60. The rotating shaft 25 of the motor 20 is arranged to extend in the front-rear direction, and a speed reduction mechanism 40 using a planetary gear and a rotary impact mechanism 50 for converting the rotational force output by the speed reduction mechanism 40 into impact force and transmitting it to the tool holder 35 are arranged side by side on the rotation axis A1 on the front side of the rotating shaft 25. The brushless motor 20 is driven by an inverter circuit (not shown), and a rotor core 23 having a permanent magnet 24 rotates on the inside, and a stator having a coil 22 wound around a stator core 21 is arranged on the outer periphery side. The rotating shaft 25 passes through the rotor core 23, and the rotating shaft is supported by a bearing 28 on the front side and a bearing 29 on the rear side. The bearing 28 is a ball bearing, and its outer ring is held by the inner cover 44. The bearing 29 is a ball bearing, and is held by a bearing holder 68 formed on the inner wall side of the rear cover 60.

[0019] The hammer case 3 has a bell-like shape with a gradually tapered tip, a cylindrical through hole 3a is formed at the tip, and a bearing 49 such as a needle bearing is attached inside the through hole 3a. The rotary impact mechanism 50 including the anvil 55, the reduction mechanism 40, and the bearings 45, 49 are housed inside the hammer case 3, and the inside is sufficiently filled with grease for lubrication. The opening on the rear side of the hammer case 3 is closed by an inner cover 44. The anvil 55 exposed to the front side from the through hole 3a on the front side of the hammer case 3 constitutes an output shaft, and a tip tool holder 35 for holding a tip tool (not shown) is provided at its tip.

[0020] An opening surface 63 of the rear cover 60 is connected to the rear opening 11b of the main housing 10. A substantially circular circuit board 30 having a semiconductor switching element, for example, a Hall IC 31, mounted thereon is provided on the front side of the motor 20. The circuit board 30 is on the front side of the motor 20, i.e., on the main housing 10 side, and is accommodated within the internal space of the main housing 10. A cooling fan 33 is provided on the rotating shaft 25 on the rear side of the motor 20. The fan 33 draws in outside air from air windows 18 (see FIG. 2 below for reference symbols) provided on both the left and right sides of the main housing 10, and flows the air from front to rear in the direction of the rotation axis A1, thereby cooling the motor 20 and electronic elements mounted on the circuit board 30. The left and right side surfaces and the lower side surface of the rear cover 60 are formed with an air window 64 (see FIG. 2 for the reference numerals) for exhausting air and a first through hole 65. Most of the cooling air is exhausted to the outside through the air window 64, and the rest is introduced into the body part 11 of the main housing 10 through the first through hole 65. In order to allow the air to flow into the main housing 10, the main housing 10 is formed with a protruding part 14 protruding rearward, and the first through hole 65 communicates with a second through hole 15 (inlet part) formed in the protruding part 14. The air that has flowed into the protruding part 14 of the main housing 10 is exhausted to the outside through an air window 19 formed in the body part 11 of the main housing 10. The air window 18 corresponds to the first intake part in the present invention. The air window 19 corresponds to the second exhaust part in the present invention.

[0021] In this way, the space for accommodating the motor 20 is defined by the main housing 10 and the rear cover 60, but any type of motor 20 can be used. In Fig. 1, a brushless DC motor is used. Since the stator core 21 of the brushless motor 20 is held by the main housing 10, the rear cover 60 essentially holds the bearings 29 and serves the function of accommodating the fan 33.

[0022] The rotating shaft 25 of the motor 20 is connected to the reduction gear mechanism 40. The reduction gear mechanism 40 reduces the output of the motor 20 at a predetermined reduction ratio and transmits it to the spindle 46, and is a mechanism using planetary gears in this embodiment. The reduction gear mechanism 40 includes a sun gear 41 fixed to the tip of the rotating shaft 25 of the motor 20, a ring gear 43 provided on the outer periphery of the sun gear 41 so as to surround it at a distance, and a plurality of planetary gears 42 disposed in the space between the sun gear 41 and the ring gear 43 and meshed with both of these gears. The ring gear 43 is a ring-shaped member having a gear formed on the inner periphery thereof, and is fixed to the main housing 10 via an inner cover 44. The sun gear 41 is a spur gear that serves as the input part of the reduction gear mechanism 40. Between the outer gear surface of the sun gear 41 and the inner gear surface of the ring gear 43, the three planetary gears 42 revolve around the sun gear 41 while rotating on their own axes, so that the spindle 46, which functions as a planetary carrier, rotates at a reduced speed at a predetermined ratio.

[0023] The inner cover 44 is a part manufactured by integral molding of synthetic resin, and is held by being sandwiched from the left and right directions by the body part 11 of the main housing 10. At this time, the inner cover 44 is held so as not to rotate relative to the main housing 10. The main role of the inner cover 44 is to hold the bearing 45 provided in the rotary impact mechanism, and to hold the bearing 28 formed on the front side of the motor 20, thereby positioning it in the axial direction. The bearing 45 held by the inner cover 44 is for supporting the rear end of the spindle 46, and is, for example, a ball bearing. The rotary impact mechanism 50 is configured to be sandwiched between the hammer case 3 and the inner cover 44 to prevent grease leakage, and the air flow around the motor 20 hardly flows toward the reduction mechanism 40 or the rotary impact mechanism 50.

[0024] A spindle cam groove 46a is formed on the outer peripheral surface of the spindle 46 which is formed integrally with the planetary carrier portion. The hammer 51 is disposed on the outer peripheral side of the shaft portion of the spindle 46, and a hammer cam groove 52 is formed on the inner peripheral side. The hammer 51 is held by a cam mechanism using a cam ball 47 which is movable inside the spindle cam groove 46a and the hammer cam groove 52. The front side of the hammer spring 48 abuts against the hammer 51 side, and the rear side abuts against the planetary carrier portion of the spindle 46.

[0025] At the rear end of the anvil 55, two vanes 56 that serve as the parts to be struck are formed at positions 180 degrees apart in the circumferential direction. The vanes 56 are shaped to extend radially outward, and are struck by the striking claws of the hammer 51. The rotating body of the spindle 46 and the anvil 55 is axially supported on the front side by the inner wall of the hammer case 3 via a bearing 49. The shapes of the hammer 51 and the vanes 56 are arbitrary, and the number of vanes 56 in the circumferential direction may be three instead of two, or any other number.

[0026] The tool holder 35 includes a mounting hole 57 having a hexagonal cross section extending axially rearward from the front end of the anvil 55, two holes formed at two circumferential locations and penetrating in the radial direction for arranging the steel balls 37, and a sleeve 36 provided on the outer periphery. A spring 38 is attached inside the sleeve 36 to bias the sleeve 36 rearward.

[0027] The rotational driving force of the motor 20 is transmitted from the rotary shaft 25 to the rotary impact mechanism 50 via the reduction mechanism 40 using planetary gears. The reduction mechanism 40 transmits the output of the motor 20 to the spindle 46, and the revolution motion of the planetary gear 42 is converted into the rotation motion of the planetary carrier, causing the spindle 46 to rotate. When the spindle 46 rotates, the hammer 51 rotates accordingly, causing the anvil 55 to rotate. While the load applied from the hammer 51 to the anvil 55 is small, the hammer 51 rotates almost interlocking with the spindle 46. When the reaction force received from the tip tool becomes large, the cam ball 47 moves, causing the relative positions of the hammer 51 and the spindle 46 in the rotational direction to vary slightly, causing the relative positions of the hammer 51 and the spindle 46 in the rotational direction to vary slightly, causing the hammer 51 to move backward while compressing the hammer spring 48. The rearward movement of the hammer 51 is caused by compressing the hammer spring 48.

[0028] As the hammer 51 moves backward, the striking claw of the hammer 51 passes over the wing portion 56 of the anvil 55, and the engagement between them is released. Then, the hammer 51 is rapidly accelerated in the rotational direction and forward by the rotational force of the spindle 46, as well as the elastic energy stored in the hammer spring 48 and the action of the cam mechanism, and is moved forward, i.e., toward the anvil 55, by the biasing force of the hammer spring 48, and the striking claw of the hammer 51 re-engages with the wing portion 56 of the anvil 55 and starts to rotate integrally. At this time, a strong rotational striking force is applied to the anvil 55, which transmits the rotational striking force to a tip tool (not shown) attached to the anvil 55. Thereafter, the same operation is repeated to tighten the screw or the like.

[0029] FIG. 2 is a partial side view of the main housing 10 in FIG. 1. The main housing 10 has a front opening 11a for mounting the hammer case 3 at its front, and a rear opening 11b for mounting the rear cover 60 at its rear. The main housing 10 is divided into left and right parts with a vertical plane passing through the rotation axis A1 of the motor 20 as a dividing plane, and the left and right divided pieces are fixed by a plurality of screws 17a to 17h (17e to 17h are not visible in the figure). The rear cover 60 has a cylindrical shape with one end (front end) in the direction of the rotation axis A1 formed as an opening surface 63 that opens, and the other end (rear end) closed as a rear wall portion 62. The rear cover 60 is attached to the main housing 10 from the rear to the front in the direction of the rotation axis A1, and is fixed by a plurality of screws 71a to 71d (see FIG. 6) described later. The impact tool 1 has a side surface provided with an air window (intake port) 18 for drawing in outside air, and air windows (exhaust ports) 64, 19 for discharging air. The air window 18 for drawing in outside air is formed at approximately the same position as the circuit board 30 (see FIG. 1) when viewed in the direction of the rotation axis A1, and is formed by forming 12 small oval openings in the vertical direction on the right side surface of the body 11. The group of openings that form the air window 18 are formed integrally with the main housing 10 when the main housing 10 is molded, and communicate the internal space of the main housing 10 with the outside.

[0030] The rear cover 60 is manufactured by integral molding of synthetic resin. The rear cover 60 has a cylindrical cylindrical portion 61, and an opening surface 63 is formed on the front side of the cylindrical portion 61, and the rear side becomes a rear wall portion 62. An air window 64 is formed on the right side surface of the cylindrical portion 61 of the rear cover 60. The air window 64 is formed by a number of elongated slits in the vertical direction, and these slits enable air communication between the internal space of the rear cover 60 and the outside. The air window 64 is the third exhaust portion of the present invention. The air window 64 is formed not only on the right side surface of the cylindrical portion 61 but also on the left side surface in the same manner. In the conventional impact tool 1, only the air windows 64 formed on both the left and right side surfaces functioned as exhaust ports. However, since it becomes necessary to design the rear cover 60 as small as possible as the main housing 10 becomes smaller, the size and number of slits that can be formed as the air window 64 alone cannot ensure a sufficient amount of airflow. Therefore, in the present invention, the air windows, which were previously formed only on the left and right sides of the cylindrical portion 61 of the rear cover 60, are also formed on the upper or lower surface of the cylindrical portion of the rear cover 60, thereby ensuring sufficient overall size and number of the air windows.

[0031] Regarding the idea of forming a windshield on the upper surface of the cylindrical portion of the rear cover 60, when the impact tool 1 falls onto the floor or the like, or when the rear cover 60 collides with other objects, the probability of the upper part of the rear end of the rear cover 60 being damaged is high. Therefore, it becomes newly necessary to configure the strength in the vicinity of the upper part of the rear end to be sufficiently high. In order to suppress damage, newly performing processing will lead to an increase in cost. Therefore, it is preferable to form the windshield on the lower surface rather than the upper surface of the cylindrical portion of the rear cover 60. In the case of a hand-held tool without the protruding portion 14, when a through-hole 65 (first exhaust portion) is provided as a windshield on the lower surface of the cylindrical portion of the rear cover 60, the hand 110 of the operator holding the hand-held tool may be located in the discharge direction of the warm air exhausted from the through-hole 65. When the exhaust air directly hits the hand of the operator in this way, it will lead to discomfort for the operator. Therefore, in this embodiment, the protruding portion 14 is arranged between the through-hole 65 (first exhaust portion) on the lower surface of the rear cover 60 and the hand 110 of the operator, so that the exhaust discharged from the through-hole 65 (first exhaust portion) on the lower surface of the rear cover 60 does not face the hand 110 of the operator. Whether to provide the protruding portion 14 or not is determined by factors such as the temperature of the exhaust and the distance from the exhaust portion to the hand 110 of the operator.

[0032] In the lower part of the rear cover 60, a protruding portion 14 extending rearward from the rear opening 11b of the body portion 11 is provided. The protruding portion 14 is formed with a front-rear length L1 in the direction of the rotation axis A1 from the rear opening 11b of the body portion 11 to the rear end. On the other hand, the protruding portion 14 of the rear cover 60 is formed as a part of the body portion 11 of the main housing 10, and a windshield 19, which is a second exhaust port, is formed on the side surface of the protruding portion 14. The front-rear length in the direction of the rotation axis A1 is L. In this embodiment, L1 < L, and the rear cover 60 protrudes rearward from the protruding portion 14 by L2. However, if the relationship is L1 ≦ L, the extension amount of the protruding portion 14 rearward can be set arbitrarily. However, making the relationship L1 > L is not preferable because the possibility of the rear end of the protruding portion 14 hitting other objects and being damaged increases. The windshield 19 is provided on the side surface of the body portion 11 of the main housing 10 near the rear end and near the handle portion 12.

[0033] The ventilating window 19, which is the second exhaust section, is preferably provided symmetrically with respect to a vertical plane passing through the rotation axis A1, but the installation location may be anywhere on the main housing 10 as long as the wind does not hit the operator's hand 110 and there is no problem with strength, and may be provided asymmetrically on the left and right sides of the main housing 10, and the size and number of the ventilating window may be freely determined. The opening portion adjacent to the fan 33, such as the ventilating window 64, must be configured so that when a wire or the like is inserted, the wire or the like does not come into contact with the built-in fan 33. The ventilating window 19, the through hole 15, and the through hole 65 of the present invention are themselves arranged in a labyrinth structure, and are configured so that foreign matter from the outside is unlikely to come into contact with the fan 33. Therefore, the ventilating window 19 may be lattice-shaped (multiple pieces) and the through hole 65 may be oval-shaped (one piece), or the ventilating window 19 may be oval-shaped (one piece) and the through hole 65 may be lattice-shaped (multiple pieces). Furthermore, if the size is such that the intrusion of wire or the like can be prevented, the air window 19 may be made elliptical (one piece) and the through hole 65 may also be elliptical (one piece). However, for the through hole 15 whose outer periphery is surrounded by the bent portion 10c (see FIG. 3 for the reference numerals described later), it is preferable to form it into one air passage for molding reasons. A similar air window 19 is formed on the left side surface of the impact tool 1.

[0034] 3 is an enlarged view of part A in FIG. 1. The rear cover 60 is manufactured by two-layer molding, with an inner resin part 60a and an outer layer (or outer skin) of elastomer 60b having rubber properties. An opening surface 63 of the rear cover 60 and the rear opening 11b of the main housing 10 are fitted together in a spigot manner. That is, the opening edge 63a of the rear cover 60 is attached so as to be positioned outside the inner cylindrical part 11c formed near the rear opening 11b of the main housing 10. In this way, the openings of the rear cover 60 and the main housing 10 are connected in a spigot-fit manner, so that air leakage from the vicinity of the joint between the rear cover 60 and the main housing 10 can be prevented.

[0035] A through hole 65 is formed in the lower side of the rear cover 60, penetrating from the inside to the outside in the radial direction. The through hole 65 corresponds to the first through hole of the present invention, and is a hole that communicates with a part of the lower side surface 61b of the rear cover 60 in the vertical direction, and allows air to flow from the inside to the outside of the rear cover 60. A through hole 15 that opens upward at the protruding portion 14 is formed below the through hole 65. By forming the protruding portion 14 on the lower surface of the through hole 65, it is possible to prevent dust and needles from entering through the through hole 65, so that the shape of the through hole 65 can adopt any shape and size, such as a hole, a notch, or an opening. The larger the size of the through hole 65, the more the flow rate of the cooling air can be increased. The through hole 15 corresponds to the second intake part of the present invention.

[0036] The main housing 10 also has a two-layer structure, and an elastomer 10b having rubber properties is formed as an outer layer (or outer skin) on the outside of an inner resin part 10a. The lower end of the elastomer 60b of the rear cover 60 is formed with a bent part 60c formed so as to be bent inward. The elastomer 60b is not present on the lower side of the through hole 65 and in the part facing the through hole 15 of the protruding part 14. The upper end of the elastomer 10b of the main housing 10 is formed with a bent part 10c formed so as to be bent inward. The bent part 10c is configured to surround the outer periphery of the through hole 15, and the resin part 10a is not formed on the horizontal inner side of the bent part 10c, forming a large open through hole 15. The outer edge of the through hole 15 viewed in the horizontal direction is surrounded by the bent part 10c made of the elastomer 10b except for the front side, and the upper side of the bent part 10c is closely contacted with the elastomer 60b bent at approximately the same length. In this way, the elastomer 10b on the main housing 10 side and the elastomer 60b on the rear cover 60 side come into close contact with each other, thereby performing a sealing function that closes the gap at the connection portion from the through hole 65 to the through hole 15. Furthermore, the close contact between the bent portion 10c and the bent portion 60c can attenuate the impact load transmitted from the rear cover 60 to the main housing 10 when, for example, the product is dropped, thereby improving the durability of the impact tool 1.

[0037] One or more through holes 65 are formed in a portion located on the lower side of the cylindrical portion of the rear cover 60, and a part of the wind generated by the fan 33 flows into the protruding portion 14 side through the through holes 65. As described above, for example, the wind window 19 may be formed in a lattice shape (multiple pieces) and the through hole 65 may be formed in an oval shape (one piece), or the wind window 19 (second exhaust portion) may be formed in an oval shape (one piece) and the through hole 65 may be formed in a lattice shape (multiple pieces). Furthermore, the wind window 19 may be formed in an oval shape (one piece) and the through hole 65 may be formed in an oval shape (one piece) as long as the shape is small enough to prevent the intrusion of wires or the like. Since the through hole 15 on the protruding portion 14 side is formed to be a sufficiently large opening, the air flowing through the through hole 65 flows without leakage into the inside of the main housing 10, in this case, into the protruding portion 14 formed as a part of the body portion 11. The wind window 19 corresponds to the second exhaust portion in the present invention.

[0038] The air that has flowed into the internal space of the protruding portion 14 is discharged to the outside of the main housing 10 by three methods. The main discharge path is to discharge the air that has flowed in from the through hole 15 to the outside through the air windows 19 formed on both the left and right sides of the protruding portion 14. This exhaust path is the path shown by the dotted arrow F1 in FIG. 1. The air windows 19 are formed in a position that does not interfere with the hand 110 that is holding the handle portion 12, as shown in FIG. 1, that is, to be located above the hand. The air windows 19 are oval in the front-rear direction, and one each are formed on the right side and the left side of the protruding portion 14. The number of air windows 19 (second exhaust section) is not limited to one each on the left and right sides, but in a product that pursues miniaturization of the housing (main housing 10, rear cover 60, hammer case 3) of the impact tool 1 as in this embodiment, the air windows 19 must be arranged in a small gap, so one each on the left and right sides in this embodiment. Also, care must be taken when arranging the ventilating window 19, since if it is placed too close to the screw boss 16d or the opening face of the through hole 15, the strength of the main housing 10 will be locally reduced.

[0039] The air that has flowed into the internal space of the protruding portion 14 is discharged to the outside through the wind window 19, but it can also be discharged to the outside not only through the wind window 19 but also through a gap formed in the main housing 10. Here, it can be discharged to the outside through a gap in the through hole for the forward / reverse switching lever 7 as shown by the dotted arrow F2 in FIG. 1, and further through a gap in the opening for the trigger lever 6a as shown by the dotted arrow F3 in FIG. 1. The amount of air in the dotted arrows F2 and F3 is actually small. However, it is possible to control the amount of air in the dotted arrows F2 and F3 by optimizing the size of the gap in the through hole for the forward / reverse switching lever 7 or the through hole for the trigger lever 6a formed in the main housing 10, or the shape of the air passage. When discharging air by the fan 33 through a gap that has conventionally existed in the main housing 10 as shown by the dotted arrows F2 and F3, it is important to consider that the exhaust air does not directly hit the operator's hand 110. For this reason, it is preferable to position the air window 19 above the handle portion 12, and to make the air discharged from the gap in a horizontal direction or upward from the horizontal direction.

[0040] The sealed structure of the connection air passage from the bottom of the rear cover 60 to the inside of the protruding portion 14 of the main housing 10 in the first embodiment described above can be realized by other methods than the method of surface contact between the bent portion 10c of the elastomer 10b and the bent portion 60c of the elastomer 60b. Fig. 4 is a partially enlarged view showing modified examples 1 to 3 of the first embodiment of the present invention, which corresponds to part A in Fig. 1. Fig. 4(A) shows that the bent portion 60c shown in Fig. 3 is not formed on the rear cover 60 side, and the lower end of the elastomer 60b is brought into contact with the bent portion 10c of the elastomer 10b on the main housing 10 side. Here, the upper surface of the bent portion 10c near the front end portion comes into contact with the elastomer 60b of the rear cover 60. In this case, if the thickness of the folded portion 10c is made slightly larger than the distance between the opening surface of the through hole 15 and the surface surrounding the through hole 65, when the rear cover 60 is attached to the main housing 10 as shown in Figure 4 (A), the elastomer of the folded portion 10c is compressed in the direction perpendicular to the surface, thereby maintaining sufficient airtightness between the resin portion 60a of the rear cover 60 and the resin portion 10a of the main housing 10.

[0041] 4(B) shows that a bent portion is not formed in the elastomer 10b on the main housing 10 side, but a bent portion 60c is formed only on the rear cover 60 side. Even with this configuration, the underside of the bent portion 60c near the front end portion contacts the resin portion 10a of the main housing 10. In this case, if the thickness of the bent portion 60c is made slightly larger than the distance between the opening surface of the through hole 15 and the surface surrounding the through hole 65, the elastomer of the bent portion 60c is compressed in the normal direction of the contact surface when the rear cover 60 is attached to the main housing 10, so that sufficient sealing performance is maintained.

[0042] In FIG. 4(C), as in the first embodiment, the bent portions 10c, 60c are formed in both the elastomer 10b of the main housing 10 and the elastomer 60b of the rear cover 60, and the bent portions 10c, 60c are brought into close contact with each other. However, in this third modified example, a recess 60d and a protrusion 10d are formed in the bent portions 10c, 60c, so that a so-called spigot fitting portion is formed at the joint between the bent portions by the elastomer. In addition, a step portion 60e is formed on the resin portion 60a side to accommodate the bent portion 60c formed thicker and a part of the bent portion 10c. Although the shape of the resin portion 10a on the main housing 10 side is not changed from the first embodiment, a rib-like protrusion 10d protruding upward is formed on the inner portion of the bent portion 10c. The protrusion 10d fits into the recess 60d formed in a concave shape on the inner side of the bent portion 60c. With this configuration, it is possible to maintain a high degree of adhesion at the joint surfaces between the rear cover 60 and the main housing 10.

[0043] As described above, the first to third modified examples shown in Fig. 4 can achieve the same effect as the first embodiment shown in Fig. 1 to Fig. 3. The first to third modified examples shown in Fig. 4 are all modified examples in which the degree of sealing of the through-hole 15 is improved by the bent portions 10c, 60c, or the convex portions 10d, and concave portions 60d made of elastomer, but any connection configuration between the main housing 10 and the rear cover 60 may be adopted, not just a configuration using elastomer, as long as the configuration allows the through-hole 15 to function as an air passage. EXAMPLES

[0044] FIG. 5 is a vertical cross-sectional view of an impact tool 1A according to a second embodiment of the present invention. In the second embodiment, as the wind window (second exhaust section) 19 formed in the main housing 10 in the first embodiment, in addition to the two wind windows 19a on the left and right, a rear wind window 19b (see FIG. 6) is formed. That is, the second exhaust section is composed of a total of four wind windows 19a, 19b. The other configurations are the same as those of the first embodiment. In the view of FIG. 5, the rear wind window 19b is not visible due to the position of the vertical cross section. A part of the air discharged from the fan 33 and flowing into the main housing 10 side through the through holes 65, 15 is discharged to the rear side of the impact tool 1 from the wind window 19b (see FIG. 6 for the symbol described later) as indicated by the dotted arrow F4, and the remaining part is discharged to both the left and right sides of the impact tool 1 from the wind window 19a. Air is also discharged horizontally from the wind window 19a in both the left and right directions.

[0045] FIG. 6 is a rear view of the body 11 of the impact tool 1A of FIG. 5. The rear cover 60 has the same shape as that of the first embodiment, and is fixed to the main housing 10 by four screws 71a to 71d oriented in a direction parallel to the rotation axis A1. The outer surface of the rear wall 62 of the rear cover 60 is flat, and no ventilation window for exhaust is formed therein. The left and right side surfaces of the rear cover 60 are formed with ventilation windows 64 (see also FIG. 2). Here, if the rotation axis A1 is divided into four sections in the circumferential direction at 90 degrees each as shown by the dashed lines, the ventilation windows 64 are formed in the right side surface and the left side surface of the cylindrical portion 61 of the rear cover 60. Also, a through hole 65 (see FIG. 5 for the symbol) is formed in the rear cover 60 in a part of the lower part of the cylindrical portion 61 of the rear cover 60, i.e., in a range (opposing range θ) facing the protruding portion 14 of the main housing 10. In this way, in the rear cover 60, by providing the through holes 65 on the surfaces other than the left and right side surfaces of the rear cover 60, it is possible to add an exhaust path such as the dotted arrow F4 shown in FIG. 5 or the dotted arrow F5 shown in this figure, so that the area of ​​the exhaust port can be increased compared to the conventional case. Since the flow rate of the cooling air increases with the increase in the exhaust path, the cooling performance of heat-generating parts such as the motor and the inverter circuit is improved. Note that, although no air window (third exhaust section) is provided in the upper part of the cylindrical section 61 of the rear cover 60 in the first and second embodiments, an air window may be provided on the upper side surface of the rear cover 60 as long as the strength of the rear cover 60 can be sufficiently ensured. EXAMPLES

[0046] FIG. 7 is a vertical cross-sectional view of an impact tool 1B according to a third embodiment of the present invention. In the first and second embodiments described above, the air flowing into the protruding portion 14 of the main housing 10 through the through hole 65 is discharged to the outside through an exhaust port or gap formed on the main housing 10 side. In the third embodiment, the upper portion of the protruding portion 14 of the main housing 10 is not tightly attached to the rear cover 60, but is instead separated from the upper portion of the protruding portion 14 of the main housing 10 and the cylindrical portion 61 of the rear cover 60 to form a small gap, through which air is discharged into the atmosphere. The upper portion of the protruding portion 14 is formed as a wall surface 14a, not as a through hole 15 as shown in FIG. 3, so that the air discharged from the rear cover 60 does not flow into the inside of the protruding portion 14. In FIG. 7, as shown by the dotted arrow F6, the air discharged from the through hole 65 flows rearward along the upper surface of the wall surface 14a and is discharged into the atmosphere. In addition, although the dotted arrow F6 in FIG. 7 is shown as flowing only backward, the gap 8 extends from the opening of the through-hole 65 in a direction of approximately 180 degrees in the left-right direction and diagonally backward, so that the air is discharged so as to be diffused toward the right side and the left side as well.

[0047] FIG. 8 is a rear view of the body 11 of the impact tool 1B of FIG. 7. The rear cover 60 has the same shape as in the first and second embodiments, and is fixed to the main housing 10 with four screws 71a to 71d. No exhaust window is formed in the rear wall 62 of the rear cover 60, but windows 64 (second through holes; see FIG. 2) are formed on both the left and right side surfaces. A through hole 65 (see FIG. 7 for the reference number) is formed in a part of the lower portion of the cylindrical portion 61 of the rear cover 60. The lower side surface 61b of the rear cover 60 is a horizontal surface in the left-right direction, and a minute gap 8 is formed between the lower side surface 61b and the horizontal upper surface of the protruding portion 14. The distance of the gap 8 is constant except for the left and right peripheral edges.

[0048] 9 is a diagram of an impact tool 1C according to a first modified example of the third embodiment of the present invention, in which (A) is a vertical cross-sectional view passing through the rotation axis A1, and (B) is a rear view. In this example, in order to improve the discharge efficiency from the gap 8, the gap 8 is formed so that the vertical distance becomes slightly larger from the front to the rear, that is, so that the diameter increases. In order to realize such a gap 8, the upper surface 14b of the protruding portion 14 is formed as an inclined surface that descends slightly toward the rear, or the upper surface of the lower side surface 61b of the cylindrical portion of the rear cover 60 is formed as an inclined surface that ascends slightly toward the rear, or both of these are applied.

[0049] In FIG. 9B, the gap 8 is configured to be almost horizontal in the left-right direction. Since the position of the operator's hand 110 is near the protruding portion 14, the air passage is configured to be horizontal in the left-right direction so as not to exhaust air in the direction of the protruding portion 14. The curved portion 61c is formed so that the left-right distance between the lower opposing surfaces of the curved portion 61c on both the left and right sides is shorter than the left-right distance of the upper surface 14b of the protruding portion 14. By forming the curved portion 61c on both the left and right sides in this manner, the air exhausted from the through hole 65 and flowing leftward or rightward on the upper surface 14b of the protruding portion 14 is exhausted into the atmosphere while diffusing upward from the upper surface 14b near the curved portion 61c, so that the exhaust air is less likely to hit the operator's hand.

[0050] As described above, in the first modified example of the third embodiment, the gap 8 is formed between the rear cover 60 and the protruding portion 14, and the gap 8 is formed so that the width thereof widens toward the rear, thereby improving exhaust efficiency. Also, the width of the gap 8 becomes larger toward the rear, and the gap 8 is formed so that it becomes larger below the curved portion 61c, improving the ease of assembly when assembling the rear cover 60 to the main housing 10.

[0051] FIG. 10 is a diagram of an impact tool 1D according to a second modified example of the third embodiment of the present invention, in which (A) is a vertical cross-sectional view passing through the rotation axis A1, and (B) is a rear view. In FIG. 10, the upper surface of the protruding portion 14 of the rear cover 60 is formed as an inclined surface 14c that rises slightly toward the rear. This configuration is not intended to increase exhaust efficiency, but is intended to prevent foreign matter from entering the through hole through the gap. Of the air exhausted from the through hole 65, the air flowing rearward in the direction of the rotation axis A1 flows along the inclined surface 14c, and is discharged slightly diagonally upward at the rear edge of the gap 8 into the atmosphere. As a result, the exhaust air flows in a direction away from the hand, making it difficult for the exhaust air to hit the hand 110 of the operator. In the configuration of FIG. 10(B), the gap 8 is configured to be approximately horizontal in the left-right direction, similar to the configuration of FIG. 9(B). Since the position of the operator's hands 110 will be near the protrusion 14, in order to prevent wind from being discharged in the direction of the protrusion 14, the left-right length of the lower side surface of the rear cover 60 is made shorter than the left-right length of the inclined surface 14c that forms the lower surface in the left-right direction.

[0052] The present invention has been described above based on the embodiments, but the present invention is not limited to the above-mentioned embodiments and various modifications are possible within the scope of the present invention. For example, in FIG. 9(B), the gap 8 that serves as the air passage is configured to be almost horizontal in the left-right direction, but in order to configure the air not to be discharged to the hand 110 of the operator, the inclined surface 14 may be angled in the left-right direction and curved downward so that both the left and right sides are slightly upward from the horizontal direction. In addition, for example, when the left-right split main housing is assembled, the upper surface of the protruding portion 14 may be configured to be concave downward or have a bow-shaped vertical cross section, so that the air discharged from the through hole 65 and hitting the upper surface of the protruding portion 14 flows along the inclined surface of the upper surface of the protruding portion 14, and the discharge direction can be changed to be slightly upward from the horizontal plane. In the above-mentioned embodiment, the impact tool 1 is used as an example of a working machine, but the working machine is not limited to an impact tool, and the present invention can be applied to any working machine as long as it has a similar main housing and rear cover. [Explanation of symbols]

[0053] 1, 1A~1D Impact tool 3 Hammer case 3a Through hole 5 Cover 6 Trigger switch 6a Trigger lever 7 forward / reverse switching lever 8 gap 10 main housing 10a resin portion 10b elastomer 10c bent portion 10d protrusion 11 body portion 11a Front opening 11b Rear opening 11c Inner cylindrical part 12 handle portion 13 battery pack attachment portion 14 protrusion portion 14a wall surface 14b, 14c upper surface (inclined surface) 15 opening (second intake section) 16a~16h Screw boss 17a~17h Screw 18 Air window (first intake section) 19, 19a, 19b Air window (second exhaust section) 20 motor 21 stator core 22 coil 23 rotor core 24 permanent magnet 25 rotating shaft 28, 29 bearing 30 circuit board 31 Hall IC 33 Fan 34 Control circuit board 35 Tool holder 36 Sleeve 37 Steel ball 38 spring 40 reduction mechanism 41 sun gear 42 Planetary gear 43 Ring gear 44 Inner cover 45 Bearing 46 Spindle 46a Spindle cam groove 47 Cam ball 48 Hammer spring 49 Bearing 50 Rotary impact mechanism 51 Hammer 52 Hammer cam groove 55 Anvil 56 Wing 57 Mounting hole 60 Rear cover 60a Resin part 60b Elastomer 60c (Elastomer) bent part 60d (elastomer) recess 60e (resin) step 61 cylindrical portion 61b lower side surface (of the cylindrical portion) 61c curved portion 62 Rear wall 63 Opening surface 63a Opening edge 64 Air window (third exhaust section) 65 Through hole (first exhaust section) 68 Bearing holder 71a~71d Screws 100 Battery pack 101 Latch button 110 (operator's) hand A1 Rotation axis

Claims

1. A motor that drives the tool; a main housing that houses at least a portion of the motor, extends in a front-rear direction, and has a body portion that is open at a rear end; and a rear cover that is connected to the opening; a protrusion formed as a part of the main housing and extending rearward beyond the opening; a fan driven by rotation of the motor; A first intake section provided in the body section and configured to take in outside air into the body section by the fan; a first exhaust portion that is provided in the rear cover and that exhausts air that is taken in from the first intake portion by the fan and has cooled the motor, the first exhaust portion is provided on a side surface of the rear cover at a portion facing the protruding portion, A second intake portion is formed in the protruding portion at a position opposite to the first exhaust portion, The air discharged from the first exhaust section flows again into the main housing through the second intake section, The working machine according to claim 1, wherein the air that has flowed in is exhausted to the outside through a second exhaust portion formed in the main housing.

2. The work machine according to claim 1, wherein the first exhaust portion is provided on a lower side surface of the rear cover.

3. A handle portion that is gripped by an operator is provided below the main housing, 3. The work machine according to claim 1, wherein the protrusion is provided on a lower side of the rear cover.

4. A work machine as described in any one of claims 1 to 3, characterized in that a third exhaust section for discharging air taken in from the first intake section by the fan to the outside is formed on the left or right side or upper part of the rear cover, at a position not facing the protrusion.

5. The work machine according to claim 1 , wherein the second exhaust portion is provided in the protruding portion.

6. a switch operation unit for starting the motor and a switching lever for switching the rotation direction of the motor are provided so as to be exposed to the outside from inside the main housing, The work machine according to claim 1, characterized in that a portion of the air taken in from the second intake section is discharged to the outside through the gap between the operating section and the main housing and / or the gap between the switching lever and the main housing.

7. The work machine according to claim 3, characterized in that the second exhaust section is positioned above the handle portion of the main housing, and air exhausted from the second exhaust section is discharged in a direction other than toward the hand of an operator holding the handle portion.

8. At least a portion of the main housing and the rear cover are made of an elastomer, 2. The work machine according to claim 1, wherein the connection between the first exhaust section and the second intake section is sealed by tight contact between the elastomer on the main housing side and the elastomer on the rear cover side.

9. 2. The work machine according to claim 1, wherein a gap is provided between the rear cover and the protruding portion, and air discharged from the first exhaust portion is discharged into the atmosphere through the gap.

10. The work machine according to claim 9, wherein the gap is formed so as to open in the left / right direction or rearward.

11. 4. The work machine according to claim 3, wherein an upper surface of the protrusion is downwardly concave.

12. A battery pack attachment section for attaching and detaching a battery pack is provided at a lower end of the handle section, 4. The work machine according to claim 3, wherein the main housing is configured as a left and right split type, and has the body portion, the handle portion, and the battery pack attachment portion.

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