JP2014004642A - Hammering tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hammering tool capable of obtaining a stable hammering action.SOLUTION: An electric hammer 1 includes a motor 21 for generating rotary drive power, a motor housing 20 for accommodating the motor 21, a cylinder 31, a piston 33 provided so as to be moved back and forth along an axial direction of the cylinder 31 inside the cylinder 31 by the rotary drive power of the motor 21, and a crank case 30C for partially accommodating the cylinder 31. On the motor housing 20, a suction port 20e for fetching outside air by a rotation of a cooling fan 22B, and an exhaust port 20a for exhausting the air fetched from the suction port 20e are formed. On the crank case 30C, an auxiliary exhaust port 30b is formed. The auxiliary exhaust port 30b is closed by a shielding member 45 in an initial state. When a tip tool 50 is pressed to a work material, an auxiliary exhaust port 20b is opened.

Description

  The present invention relates to a striking tool such as an electric hammer or a hammer drill, and more particularly to a striking tool that imparts a striking force to a tip tool.

  As an impact mechanism of an impact tool, as disclosed in Patent Document 1, a piston that is reciprocated by a crank that converts the rotational force of a motor into a reciprocating motion and is disposed so as to be reciprocable within the cylinder, and an impact mechanism that is disposed within the cylinder. A configuration is known that includes a striking element that transmits a reciprocating motion of a piston via an air chamber in a cylinder and transmits a striking force to a tip tool. In the striking tool of this configuration, the transition from the no-load state to the load state, that is, by pressing the tip tool against the work material, the striker moves to the anti-tip tool side (piston side), and the piston in the cylinder The pressure of the air chamber formed between the striking element and the striking element is increased, and the striking force is transmitted to the tip tool through the striking element by the pressure fluctuation of the air chamber due to the reciprocation of the piston.

  The piston receives a reaction when the air chamber is compressed, and the load generated by the reaction is transmitted to the motor via the crank, gear, etc., and the rotational speed of the motor is reduced. In other words, a decrease in the rotational speed of the motor is a phenomenon resulting from the transition to a load state in which a striking operation is performed. In general, the rotational speed of a motor in a loaded state is a numerical value lower than that in a no-load state. Is shown. In addition, the rotation speed decreases in the load state and converges to a constant rotation speed according to the load condition, which means that the motor output characteristics, cylinder, piston, striker shape, stroke amount, etc. The converged rotation speed becomes a rotation speed suitable for the load state.

Japanese Patent No. 4556180

  Since the rotation speed in the no-load state is higher than the constant rotation speed in accordance with the above-described load state, when the transition from the no-load state to the load state, the striker cannot follow the piston phase change, Defects may occur.

  In particular, when a pressure drop inside the impact tool main body occurs, the impact failure occurs remarkably. This pressure drop means that after the impact tool is used, the temperature of the main body, which has become high, drops to room temperature, and the pressure inside the impact mechanism section decreases accordingly. It means that the pressure inside the striking mechanism is negative compared to before use of the main body because air has flowed out. When the main body is used in this negative pressure state, the amplitude of the reciprocating motion of the striker is reduced due to a decrease in the compression force of the air chamber, and the striker returns without going to the strike point, or the velocity at the strike point increases. Since it is small and the rebounding speed is small, the amplitude energy of the striker is not amplified, and the strike force is remarkably reduced, or the strike failure does not shift to the strike action state.

  Therefore, an object of the present invention is to provide a striking tool that solves the above-described problems of the prior art and obtains a stable striking motion.

  In order to achieve the above object, the present invention includes a motor that generates a rotational driving force, a cooling fan that is rotated by the rotational driving force of the motor, the motor and the cooling fan, and an outside air that is rotated by the rotation of the cooling fan. A housing formed with an intake port for taking in air, an exhaust port for exhausting air taken in from the intake port, a cylinder housed in the housing, and a rotational driving force of the motor, A piston provided so as to be capable of reciprocating along the axial direction of the cylinder, a striking force transmission mechanism for converting the reciprocating motion of the piston into a striking force and transmitting it to the tip tool, and in conjunction with the operation of the tip tool; There is provided a striking tool including an exhaust port adjusting portion that changes an opening area of the exhaust port.

  According to such a configuration, since the exhaust port adjustment unit changes the opening area of the exhaust port, the exhaust air volume changes according to the change in the opening area. Thereby, the work amount of the motor increases and the rotation speed decreases. Since the exhaust port adjustment unit changes the opening area of the exhaust port in conjunction with the operation of the tip tool, the opening area is changed by pressing the tip tool against the work material at the start of work, and the motor speed is changed. Can be reduced. Even if the pressure in the air chamber becomes negative compared to before use, since the piston operation starts from a state where the rotational speed of the motor is low, the striking force transmission mechanism can easily follow the reciprocating motion of the piston. As a result, it is possible to avoid a situation in which the striking force is remarkably reduced at the initial stage of operation and the transition to the striking operation is not performed.

  Moreover, it is desirable that the exhaust port is constituted by a first exhaust port that is always open and a second exhaust port that is opened and closed by the exhaust port adjustment unit.

  According to such a structure, the structure of this invention is realizable by providing a 2nd exhaust port newly, utilizing the 1st exhaust port provided conventionally.

  The housing further includes a casing that accommodates the cylinder and the piston, and the second exhaust port is formed in the casing so that the casing is cooled by the exhaust from the second exhaust port. It is desirable.

  According to such a structure, the casing which accommodates the cylinder and piston whose temperature rises by the striking operation can be cooled by the exhaust air. As a result, it is possible to prevent the temperature from rising excessively during the striking operation, and to reduce the negative pressure of the air chamber due to the temperature drop after the completion of the work.

  Further, the striking force transmission mechanism includes a striking element that reciprocates in the cylinder in conjunction with the operation of the piston, and an intermediate element that is struck by the striking element and strikes the tip tool. The adjusting portion includes a moving portion that can move a predetermined distance in the longitudinal direction of the cylinder in conjunction with the operation of the meson, and a shielding member that is connected to the moving portion and opens and closes the second exhaust port. Is desirable.

  According to such a configuration, since the shielding member opens and closes the second exhaust port in conjunction with the operation of the meson, the second exhaust port is opened by pressing the tip tool against the work material, and the rotational speed of the motor is reduced. Can be reduced. As a result, it is possible to avoid a situation in which the striking force is remarkably reduced at the initial stage of operation and the transition to the striking operation is not performed.

  Moreover, it is desirable that at least a part of the shielding member is exposed to the outside.

  According to such a configuration, since at least a part of the shielding member is exposed to the outside, the shielding member can be easily accessed, and maintainability is improved. Further, even if the second exhaust port is clogged with foreign matter or dust, it can be easily removed.

  Moreover, it is desirable to further provide an outer case that covers the shielding member.

  According to such a configuration, the shielding member can be protected by the outer case.

  Further, an air chamber is formed between the striker and the piston, a through hole is formed in the cylinder so as to communicate with the air chamber, and the moving part can open and close the through hole. desirable.

  According to such a configuration, since the through hole can be opened and closed by movement without newly providing a member for opening and closing the through hole, the number of parts can be reduced.

  According to the present invention, it is possible to provide a striking tool capable of solving the above-described problems of the prior art and obtaining a stable striking operation.

1 is a side sectional view showing an entire impact tool according to a first embodiment of the present invention. 1 is a side sectional view of a motor cover of an impact tool according to a first embodiment of the present invention. The top view of the impact tool motor cover by the 1st Embodiment of this invention. The fragmentary sectional view of the impact tool by a 1st embodiment of the present invention. The impact tool by the 1st Embodiment of this invention WHEREIN: Side sectional drawing when an auxiliary exhaust port is a closed state. The impact tool by the 1st Embodiment of this invention WHEREIN: Upper sectional drawing when an auxiliary | assistant exhaust port is a closed state. The impact tool by the 2nd Embodiment of this invention WHEREIN: Upper sectional drawing when an auxiliary | assistant exhaust port is an open state. The impact tool by the 3rd Embodiment of this invention WHEREIN: Upper sectional drawing when an auxiliary | assistant exhaust port is an open state.

  An impact tool according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view showing an entire electric hammer 1 which is a typical striking tool, and a handle part 10, a motor housing 20, and an outer frame member 30 constitute a casing. A tool holding portion 60 that detachably holds the tip tool 50 is disposed on the side of the outer frame member 30 opposite to the handle portion 10. In the following description, the side on which the tip tool 50 is provided will be referred to as the front side, the handle portion 10 side as the rear side, the extending direction of the motor housing 20 as the lower side, and the reverse as the upper side.

  A power cable 11 is attached to the handle portion 10 and a trigger 12 that can be operated by a user is attached. By connecting the power cable 11 to an external power source (not shown) and operating the trigger 12, the power supply can be switched between connection and disconnection.

  The motor housing 20 is provided in front of the handle portion 10. Although the handle portion 10 and the motor housing 20 have separate structures, they can be made of plastic and integrally molded. The outer frame member 30 is located above and in front of the motor housing 20.

  A motor 21 is accommodated in the motor housing 20. The motor 21 includes a motor pinion shaft 22 and outputs a rotational driving force. An intake port 20e for taking in cooling air for cooling the motor 21 is formed on the lower surface of the motor housing 20, and an upper end portion of the motor housing 20 opens forward and is taken in from the intake port 20e. An exhaust port 20a for exhausting wind is formed. The exhaust port 20a corresponds to the first exhaust port of the present invention.

  A motor cover 20 </ b> A shown in FIGS. 2 and 3 is provided between the motor housing 20 and the outer frame member 30. A communication port 20b penetrating in the axial direction of the motor pinion shaft 22 is formed on the upper surface of the motor cover 20A. The motor cover 20A is formed with an insertion hole 20c that penetrates in the axial direction of the motor pinion shaft 22 and through which the motor pinion shaft 22 is inserted, and a crankshaft 23 described later is rotatably supported behind the insertion hole 20c. A support hole 20d is formed. The two communication ports 20b are substantially rectangular and are formed with two insertion holes 20c therebetween. The second outer frame member 30B corresponds to the outer case of the present invention.

  The upper portion of the motor pinion shaft 22 is rotatably supported by the motor cover 20 </ b> A, and the lower portion of the motor pinion shaft 22 is rotatably supported by the motor housing 20. A pinion 22 </ b> A is provided at the upper end of the motor pinion shaft 22. A cooling fan 22B that rotates integrally with the motor pinion shaft 22 is provided below the pinion 22A. A crankshaft 23 extends in parallel with the motor pinion shaft 22 on the rear side of the pinion 22A. The crankshaft 23 is supported on the motor cover 20A via a bearing so as to be rotatable about its axis. A gear 24 that meshes with the pinion 22 </ b> A is coaxially fixed to the lower portion of the crankshaft 23.

  A motion conversion mechanism 25 that converts the rotational motion of the motor 22 into a reciprocating motion is provided at the upper end of the crankshaft 23. The motion conversion mechanism 25 includes a crank weight 25A, a crank pin 25B, and a connecting rod 25C. The crank weight 25 </ b> A is fixed to the upper end of the crankshaft 23. The crank pin 25B is fixed to the end of the crank weight 25A. A crankpin 25B is inserted at the rear end of the connecting rod 25C.

  The outer frame member 30 includes a first outer frame member 30A that is connected to the tool holding unit 60, and a second outer frame member 30B that partially covers the first outer frame member 30A. A metal crankcase 30C that houses the motion conversion mechanism 25 is provided in the second outer frame member 30B. As shown in FIG. 6, the crankcase 30 </ b> C is formed with an insertion hole 30 a that penetrates in the front-rear direction and into which an arm portion 44 described later is inserted. An O-ring 30D as a sealing material is provided in the insertion hole 30a. As shown by the dotted line in FIG. 6, the crankcase 30 </ b> C is formed with substantially rectangular auxiliary exhaust ports 30 b on both sides in the left-right direction with the cylinder 31 interposed therebetween. The auxiliary exhaust port 30b has substantially the same shape as the communication port 20b, and the positions thereof coincide with each other in the vertical direction. The crankcase 30C is covered with a second outer frame member 30B, and an external exhaust port (not shown) communicating with the outside is formed in the second outer frame member 30B. Therefore, the exhaust from the motor 21 is discharged to the outside through the communication port 20b, the auxiliary exhaust port 30b, and an external exhaust port (not shown). The crankcase 30C and the motor cover 20A are fixed to each other with a plurality of bolts 13. The crankcase 30C corresponds to the casing of the present invention. The auxiliary exhaust port 30b corresponds to the second exhaust port of the present invention.

  The first outer frame member 30 </ b> A, the crankcase 30 </ b> C, and the tool holding unit 60 accommodate a cylinder 31 that extends in a direction orthogonal to the motor pinion shaft 22. In the following description, the radial direction, the circumferential direction, and the axial direction indicate directions based on the cylinder 31 respectively. The cylinder 31 has a substantially cylindrical shape whose axial center extends in the front-rear direction, and a plurality of breathing holes 31a are formed in the circumferential direction. The cylinder 31 is further formed with a long hole 31b extending in the axial direction. The outer peripheral surface of the cylinder 31 is provided with a flange portion 31A that protrudes outward in the radial direction and comes into contact with a spring 43 described later. The cylinder 31 is configured such that the outer diameter and the inner diameter are gradually reduced toward the front. The breathing port 31a corresponds to the through hole of the present invention.

  The cylinder 31 is gripped by a cylinder holder 32 at a front portion thereof, and movement of the cylinder 31 in the forward direction is restricted. The tool holding part 60 is provided in the front-end | tip part of the cylinder 31, and the front-end tool 50 is attached so that attachment or detachment is possible.

  Inside the cylinder 31, a piston 33 is provided which can slide in the front-rear direction on the inner periphery thereof. The piston 33 has a piston pin 33A, and the piston pin 33A is inserted at the tip of the connecting rod 25C. The piston 33 is configured to reciprocate between a top dead center (most rear side) and a bottom dead center (front most side) by the motion conversion mechanism 25. In the state shown in FIG. 1, the piston 33 is located at the bottom dead center.

  A striking element 34 is disposed in front of the piston 33 in the cylinder 31 so as to be slidable in the front-rear direction on the inner periphery of the cylinder 31. The outer peripheral surface of the striker 34 selectively opens and closes the breathing hole 31a by sliding movement. A space surrounded by the piston 33, the striker 34, and the cylinder 31 is an air chamber 35.

  An intermediate element 36 is disposed in front of the striker 34 so as to be able to reciprocate in the front-rear direction. The rear end portion of the intermediate piece 36 can come into contact with the striker 34, and the strike force is transmitted to the intermediate piece 36 by the striker 34. The front end portion of the intermediate piece 36 can come into contact with the rear portion of the tip tool 50, and a striking force is transmitted from the tip portion of the intermediate piece 36 to the tip tool 50. The striking element 34 and the intermediate element 36 correspond to the striking force transmission mechanism of the present invention.

  A substantially cylindrical main body portion 36A is provided at a substantially central portion of the meson 36. A small diameter portion 36B having a smaller diameter than the main body portion 36A is provided behind the main body portion 36A, and a main body portion 36A is provided in front of the main body portion 36A. An enlarged diameter portion 36C having a larger diameter than the portion 36A is provided. A buffer member 37 is provided on the outer side in the radial direction of the main body 36A. When the step between the enlarged diameter portion 36C and the main body portion 36A and the buffer member 37 are in contact with each other, the backward movement of the intermediate element 36 is restricted.

  An annular member 38 is provided on the outer side in the radial direction of the small diameter portion 36 </ b> B of the meson 36. The annular member 38 is formed with a through hole 38a that penetrates in the axial direction and is slightly larger than the outer diameter of the small diameter portion 36B. The small diameter portion 36B is movable in the through hole 38a, and the step between the small diameter portion 36B and the main body portion 36A and the front surface of the annular member 38 come into contact with each other so that the intermediate element 36 and the annular member 38 are integrated. To move backwards.

  A pin 39 that is movable in the axial direction in the elongated hole 31b is fixed to the outer side of the annular member 38 in the radial direction. The radially outer end of the pin 39 protrudes outward through a long hole 31 b on the outer peripheral surface of the cylinder 31.

  A cylindrical member 41 slidable on the outer peripheral surface of the cylinder 31 is provided outside the cylinder 31 in the radial direction. The cylindrical member 41 is formed with a recess 41a that is recessed outward in the radial direction. When the protruding portion of the pin 39 is inserted into the recess 41a, the pin 39 and the cylindrical member 41 are engaged with each other. Therefore, it becomes possible to move backward. A sleeve 42 connected to the cylindrical member 41 and capable of sliding on the outer peripheral surface of the cylinder 31 is provided behind the cylindrical member 41. As shown in FIG. 6, the sleeve 42 has a substantially cylindrical shape, and a protruding portion 42 </ b> A that protrudes radially outward is provided at the rear end portion thereof. On the radially inner side of the protrusion 42A, a recess 42a that is recessed in the axial direction and partially accommodates a spring 43 described later is formed.

  A spring 43 that urges the sleeve 42 forward is provided between the sleeve 42 and the flange portion 31A. The front end portion of the spring 43 is in contact with the recess 42a, and the rear end portion is in contact with the flange portion 31A. Arm portions 44 extending rearward are provided in the left and right directions at the radially outer end of the protrusion 42A. Since the two arm portions 44 have the same configuration, only one arm portion 44 will be described below. As shown in FIG. 4, the arm portion 44 protrudes outward from the crankcase 30 </ b> C and has a substantially L shape in side view. Moreover, as shown in FIG. 6, since the arm part 44 is covered with the 2nd outer frame member 30B, it is not exposed outside.

  A shield member 45 capable of opening and closing the auxiliary exhaust port 30b is provided at the substantially L-shaped end of the arm portion 44. The shielding member 45 is substantially rectangular, and the area when viewed from above is set larger than the opening area of the auxiliary exhaust port 30b. The shielding member 45 is slidable on the crankcase 30C and opens and closes the auxiliary exhaust port 30b in conjunction with the movement of the meson 36. The annular member 38, the pin 39, the cylindrical member 41, the sleeve 42, and the arm portion 44 correspond to the moving portion of the present invention.

  Next, the operation of the electric hammer 1 according to the first embodiment will be described. In the initial state, as shown in FIGS. 5 and 6, the sleeve 42 is urged forward by the spring 43, and the shielding member 45 closes the auxiliary exhaust port 30b. An operator grasps the handle portion 10 by hand, pulls the trigger 12, supplies electric power to the electric motor 21, and rotates it. This rotational driving force is transmitted to the crankshaft 23 through the pinion 22A and the gear 24. The rotation of the crankshaft 23 is converted into a reciprocating motion of the piston 33 in the cylinder 31 by the motion conversion mechanism 25 (crank weight 25A, crankpin 25B, and connecting rod 25C). Further, the cooling fan 22b rotates and the cooling air sucked from the intake port 20e cools the motor 21 and is discharged to the outside from the exhaust port 20a.

  In the state of the electric hammer 1 shown in FIG. 5, since the rear end of the striker 34 is located in front of the breathing hole 31a, the breathing hole 31a is not closed and the air chamber 35 is not sealed. . Therefore, even if the piston 33 reciprocates, the pressure fluctuation in the air chamber 35 does not occur and the action of the air spring does not occur, so the striker 34 does not follow the reciprocating motion of the piston 33. Therefore, no striking force is applied to the tip tool 50.

  Next, the tip tool 50 is pressed against a workpiece (not shown). As a result, as shown in FIG. 1, the rear end surface of the intermediate piece 36 presses the striker 34 rearward to retract the striker 34, the side face of the striker 34 closes the breathing port 31 a, and the air chamber 35 is sealed. Is done. Then, the reciprocating motion of the piston 33 is transmitted to the striker 34. At the same time, the tip tool 50 and the intermediate piece 36 are pushed rearward, the stepped portion between the small diameter portion 36B and the main body portion 36A pushes the annular member 38 rearward, and the pin 39 moves rearward in the elongated hole 31b. Along with this, the sleeve 42 and the arm portion 44 move rearward, and the shielding member 45 opens the auxiliary exhaust port 30b. If it does so, the exhaust_gas | exhaustion of the motor 21 will be discharged | emitted outside from the exhaust port 20a and the auxiliary | assistant exhaust port 30b. That is, when the shielding member 45 opens the auxiliary exhaust port 30b, the opening area of the exhaust port as the entire electric hammer 1 increases. In the present embodiment, the opening area is increased by about 50%.

  As a result, the cooling fan 22b can discharge a large amount of air, so that the work amount of the motor 21 increases and the rotational speed of the motor 21 decreases. In this embodiment, the rotational speed decreases by about 5% from about 4000 rpm to about 3800 rpm. In the conventional electric hammer, when the internal temperature rises to normal temperature after use during use, the internal pressure also decreases. Therefore, the pressure in the air chamber 35 is excessively lowered. Even if the piston 33 is reciprocated in this state, the striking element 34 cannot follow the reciprocating motion of the piston 33, and a hitting defect has occurred. However, in the present embodiment, by changing the opening area of the exhaust port, the rotational speed of the motor 21 is actively lowered and the operation is started. Therefore, even if the pressure of the air chamber 35 is low, the striker 34 is not pistoned. It is possible to follow the movement of 33. That is, by reducing the rotation speed of the motor 21 at no load, the difference from the rotation speed of the motor 21 at the actual load is reduced. Thereby, it is possible to prevent hitting failure at the initial stage of operation and significant hitting force shortage. Further, when a load is applied to the tip tool 50, the rotational speed of the motor 21 is further reduced to about 3000 rpm, so that the above-described problem does not occur in the actual load state.

  According to such a configuration, the amount of exhaust air changes when the shielding member 45 opens and closes the auxiliary exhaust port 30b. As a result, the work amount of the motor 21 increases and the rotational speed decreases. Since the tip tool 50 is connected to the shielding member 45 through the meson 36, the annular member 38, the pin 39, the cylindrical member 41, the sleeve 42, and the arm portion 44, the tip tool 50 is used as a work material when starting work. By pressing, the opening area can be changed, and the rotational speed of the motor can be reduced. Even if the pressure in the air chamber becomes negative compared to before use, since the piston operation starts from a state where the rotational speed of the motor is low, the striking force transmission mechanism can easily follow the reciprocating motion of the piston. As a result, it is possible to avoid a situation in which the striking force is remarkably reduced at the initial stage of operation and the transition to the striking operation is not performed.

  According to such a configuration, since the auxiliary exhaust port 30b is formed in the crankcase 30C, the crankcase 30C that accommodates the cylinder 31 and the piston 33 whose temperature is increased by the striking operation can be cooled by the exhaust air. it can. As a result, it is possible to prevent the temperature from rising excessively during the striking operation, and to reduce the negative pressure of the air chamber due to the temperature drop after the completion of the work.

  According to such a configuration, since the shielding member 45 is covered with the second outer frame member 30B, the shielding member 45 can be protected by the second outer frame member 30B.

  Next, a second embodiment of the present invention will be described with reference to FIG. The same components are denoted by the same reference numerals and description thereof is omitted.

  In the second embodiment, the configuration of the sleeve 142 connected to the cylindrical member 41 is different from that of the sleeve 42 of the first embodiment. The sleeve 142 is formed with a recess 142a that is recessed in the axial direction from the rear surface. When the spring 43 is in contact with the recess 142a, the sleeve 142 is urged forward. The length of the concave portion 142a of the sleeve 142 in the axial direction is shorter than the length of the concave portion 42a of the first embodiment.

  In the initial state, the sleeve 142 is urged forward by the spring 43, and the breathing port 31a is opened. When the operator presses the tip tool 50 against the work material and retracts the intermediate piece 36, the inner peripheral surface of the sleeve 142 closes the breathing port 31a and the air chamber 35 is sealed, as shown in FIG. Thereby, the reciprocating motion of the piston 33 is transmitted to the striker 34.

  According to such a configuration, since the breathing port 31a is blocked by the sleeve 142, the breathing port 31a can be formed beyond the range of reciprocation of the striker 34. Thereby, the freedom degree of design of the breathing opening 31a increases. In addition, since the through hole can be opened and closed by movement without newly providing a member for opening and closing the breathing port 31a, the number of parts can be reduced.

  Next, a third embodiment of the present invention will be described with reference to FIG. The same components are denoted by the same reference numerals and description thereof is omitted.

  In the third embodiment, unlike the above-described embodiment, the second outer frame member 30B is not provided, and the outer frame member 30 is configured by only the first outer frame member 30A. Accordingly, the crankcase 30C, the motor cover 20A, the shielding member 45, and the auxiliary exhaust port 30b are exposed to the outside.

  According to such a configuration, the exhaust from the auxiliary exhaust port 30b is directly discharged to the outside, so that the exhaust resistance is reduced and the cooling fan 22b can discharge more wind. Thereby, the further reduction of the rotation speed of the motor 21 is attained.

  According to such a configuration, since the crankcase 30C, the motor cover 20A, the shielding member 45, a part of the arm portion 44, and the auxiliary exhaust port 30b are exposed to the outside, it is easy to access the above-described members. Maintainability is improved. Even if the auxiliary exhaust port 30b is clogged with dust or foreign matter, it can be easily removed.

  In addition, the impact tool by this invention is not limited to embodiment mentioned above, A various change is possible in the range of the summary of the invention described in the claim. For example, although the impact tool is an electric hammer in the embodiment, it may be a hammer drill.

  In the present invention, the area of the exhaust port as the whole electric hammer 1 is changed by opening and closing the two auxiliary exhaust ports 30b of the exhaust port 20a and the two auxiliary exhaust ports 30b. You may change the area of an exhaust port by opening and closing at least one of them.

  In the present invention, the auxiliary exhaust port 30b is formed in addition to the exhaust port 20a, and the auxiliary exhaust port 30b is closed by the shielding member 45 to change the opening area of the exhaust port of the entire electric hammer 1. It is not limited to a simple configuration. For example, the configuration may be such that the opening area of the exhaust port is changed by partially closing and opening a single exhaust port.

  In the present invention, the opening area of the exhaust port is changed by opening and closing the auxiliary exhaust port 30b to reduce the rotational speed of the motor. However, the amount of air taken into the motor housing by changing the opening area of the intake port May be increased to increase the work of the cooling fan, and the rotational speed of the motor may be decreased. Moreover, you may reduce the rotation speed of a motor by obstruct | occluding at least 1 among several inlets.

DESCRIPTION OF SYMBOLS 1: Hammer drill, 10: Handle part, 20: Motor housing, 21: Motor, 30: Outer frame member, 30C: Crankcase 31: Cylinder, 33: Piston, 34: Impactor, 35: Air chamber, 36: Meson, 38: annular member, 39: pin, 41: cylindrical member, 42: sleeve, 43: spring, 44: arm part, 45: shielding member, 50: tip tool

Claims (7)

A motor that generates rotational driving force;
A cooling fan that rotates by the rotational driving force of the motor;
A housing in which the motor and the cooling fan are housed, and an intake port for taking in outside air by rotation of the cooling fan, and an exhaust port for exhausting air taken in from the intake port;
A cylinder housed in the housing;
A piston provided so as to reciprocate along the axial direction of the cylinder by the rotational driving force of the motor;
A striking force transmission mechanism for converting the reciprocating motion of the piston into a striking force and transmitting it to the tip tool;
An impact tool comprising: an exhaust port adjustment unit that changes an opening area of the exhaust port in conjunction with the operation of the tip tool.   2. The impact tool according to claim 1, wherein the exhaust port includes a first exhaust port that is always open and a second exhaust port that is opened and closed by the exhaust port adjustment unit.   The housing further includes a casing that accommodates the cylinder and the piston, and the second exhaust port is formed in the casing to cool the casing with the exhaust from the second exhaust port. The impact tool according to claim 2, wherein The striking force transmission mechanism includes a striking element that reciprocates in the cylinder in conjunction with the operation of the piston, and an intermediate element that is struck by the striking element and strikes a tip tool.
The exhaust port adjustment unit includes a moving unit that can move a predetermined distance in the longitudinal direction of the cylinder in conjunction with the operation of the meson, and a shielding member that is connected to the moving unit and opens and closes the second exhaust port. The impact tool according to claim 2, wherein the impact tool is provided.   The impact tool according to claim 4, wherein at least a part of the shielding member is exposed to the outside.   The striking tool according to claim 4, further comprising an outer case that covers the shielding member.   An air chamber is formed between the striker and the piston, a through hole is formed in the cylinder so as to communicate with the air chamber, and the moving part can open and close the through hole. The impact tool according to claim 4.

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