Work machine

Abstract

The objective of the present invention is to improve the convenience of a work machine. The nailing machine has a pressure chamber forming part 48 including: a first case part including a cylindrical cylinder 27 and having a hollow shape; and a piston part 28 movable inside the cylinder 27, demarcating a pressure chamber 26 inside the first case part in cooperation with the first case part, and striking a stopper by moving by means of pressure of gas inside the pressure chamber 26. The pressure chamber forming part 48 has a hole part 27b of the cylinder 27 communicating the inside and the outside of the pressure chamber forming part 48, and can be switched between two states, a first state in which the pressure chamber 26 and the hole part 27b are connected, and a second state in which the pressure chamber 26 and the hole part 27b are not connected.

Description

Work equipment

[0001] The present invention relates to a work machine such as a nail driver.

[0002] One example of a work machine is a driving tool having a cylindrical cylinder, a pressure accumulator vessel provided above the cylinder, a piston that reciprocates within the cylinder, and a striking section that strikes a fastener by the downward movement of the piston.

[0003] As an example of the above-mentioned driving machine, Patent Document 1 discloses a driving machine (nail driver) in which a pressure chamber is formed by the cylinder, the pressure accumulator vessel, and the piston, and compressed gas is sealed in this pressure chamber to move the piston.

[0004] International Publication No. 2018 / 020955

[0005] In the fastener driver described in Patent Document 1, the gas in the pressure chamber leaks out to a certain extent as the period of use increases. To prevent this gas leak from the pressure chamber, the fastener driver is provided with a valve for refilling the pressure chamber with gas.

[0006] When gas leaks from the pressure chamber of the driving tool, it is necessary to replenish the gas via a valve provided in the driving tool, which may interrupt work using the driving tool and reduce the usability of the driving tool.

[0007] In order to improve the convenience of the driving tool, it is desirable to reduce the amount of gas flowing out of the pressure chamber. However, in the configuration of the driving tool in Patent Document 1, there are at least two routes for the gas in the pressure chamber to flow out to the outside: around the piston and around the valve, which causes an increase in the amount of gas flowing out of the pressure chamber.

[0008] An object of the present invention is to provide a work machine with improved convenience.

[0009] In one embodiment, the work machine has a pressure chamber forming portion including a hollow first case portion that includes a cylindrical cylinder extending in a first direction, and a piston portion that is movable in the first direction inside the cylinder, cooperates with the first case portion to define a pressure chamber inside the first case portion, and strikes a stopper by moving to one side in the first direction due to the pressure of gas inside the pressure chamber, and the pressure chamber forming portion has a first communication passage that connects the inside and outside of the pressure chamber forming portion, and is switchable between a plurality of states including a first state in which the pressure chamber and the first communication passage are connected, and a second state in which the pressure chamber and the first communication passage are not connected.

[0010] According to the present invention, the convenience of the work machine can be improved.

[0011] 6 is a side view of the structure of a working machine according to an embodiment of the present invention, and is a cross-sectional view showing a state in which the piston portion is positioned at bottom dead center. FIG. 1 is a partially enlarged cross-sectional view showing the structure around the switching valve of the working machine shown in FIG. 1. FIG. 1 is a cross-sectional view showing a state in which the piston portion is positioned at top dead center in the working machine shown in FIG. 1. FIG. 1 is a cross-sectional view showing a state in which the piston portion is positioned at a standby position in the working machine shown in FIG. 1. FIG. 1 is a partially enlarged cross-sectional view showing the structure around the switching valve when adjusting the pressure of the working machine shown in FIG. 1. FIG. 6 is a side view of the structure of a working machine according to a modified example of the present invention, and is a cross-sectional view showing a state in which the piston portion is positioned at bottom dead center. FIG. 6 is a partially enlarged cross-sectional view showing the structure around the switching valve of the working machine shown in FIG. 6. FIG. 6 is a cross-sectional view showing a state in which the piston portion is positioned at top dead center in the working machine shown in FIG. 6. FIG. 6 is a cross-sectional view showing a state in which the piston portion is positioned at a standby position in the working machine shown in FIG. 6.

[0012] A representative embodiment of a work machine according to the present invention will be described with reference to the drawings.

[0013] In this embodiment, a nail gun 10 will be described as an example of a typical work machine. The nail gun 10 shown in Fig. 1 is an air compression type work machine also known as a driving tool, and includes a housing 11, a striking unit 12, a nose unit 13, a power supply unit 14, an electric motor 15, a winding mechanism 17, and a pressure accumulator vessel 18. The housing 11 is an outer shell element of the nail gun 10 and includes a cylinder case 19, a handle 20, a motor case 21, and a mounting unit 22. The cylinder case 19 is cylindrical, and the handle 20 and the motor case 21 are connected to the cylinder case 19. The mounting unit 22 is connected to the handle 20 and the motor case 21.

[0014] The power supply unit 14 can be attached to and detached from the mounting portion 22. The electric motor 15 is disposed in a motor case 21. A head cover 25 is provided on the cylinder case 19, and the pressure accumulator vessel 18 is disposed within both the cylinder case 19 and the head cover 25.

[0015] Furthermore, a cylindrical cylinder 27 extending in the up-down direction (first direction) M1 is housed within the cylinder case 19, and the pressure accumulator vessel 18 includes a cap 23 and a holder 24 attached to the cylinder 27. The cap 23 serves as a chamber cover, and the holder 24 serves as a chamber base. The pressure accumulator vessel 18, consisting of the cap 23 and the holder 24, is a vessel that closes the upper (other) end of the cylinder 27 in the up-down direction (first direction) M1 and whose interior communicates with the interior of the cylinder 27. The cylinder 27 is made of metal, for example, aluminum or iron. The cylinder 27 is positioned relative to the cylinder case 19 in a direction along a center line A1 and in a radial direction J1 (see FIG. 2 ). The center line A1 passes through the center of the cylinder 27. The radial direction J1 is the radial direction of an imaginary circle centered on the center line A1.

[0016] Furthermore, a pressure chamber 26 is formed extending from the pressure accumulator container 18 to the cylinder 27. Specifically, the pressure accumulator container 18 and the cylinder 27 form a hollow case (first case). That is, the hollow case formed extending from the cap 23, the holder 24, and the cylinder 27 forms the pressure chamber 26, which is filled with compressed gas. The compressed gas may be air or an inert gas. Examples of inert gas include nitrogen gas and rare gas. In this embodiment, an example in which the pressure chamber 26 is filled with air will be described. Note that the pressure chamber 26 also serves as a biasing portion that biases the striking portion 12 downward (one side) in the vertical direction (first direction) M1.

[0017] The striking portion 12 is disposed from the inside to the outside of the housing 11. The striking portion 12 has a piston portion 28 and a driver blade 29. The driver blade 29 is made of, for example, metal, non-ferrous metal, or steel. The piston portion 28 and the driver blade 29 are provided as separate members, and the piston portion 28 and the driver blade 29 are connected to each other.

[0018] The piston portion 28 is operable within the cylinder 27 in a direction along the center line A1. Specifically, the piston portion 28 is movable within the cylinder 27 in a vertical direction (first direction) M1, and defines a pressure chamber 26 within the pressure accumulator container 18 and the cylinder 27 in cooperation with the pressure accumulator container 18 and the cylinder 27. The piston portion 28 strikes the nail (fastener) 78 by moving downward (one side) in the vertical direction (first direction) M1 due to the pressure of the compressed air (gas) in the pressure chamber 26. In other words, the striking portion 12, which is made up of the piston portion 28 and the driver blade 29, strikes the nail (fastener) 78 by moving downward (one side) in the vertical direction (first direction) M1 due to the pressure of the compressed air in the pressure chamber 26.

[0019] The nailing machine 10 has a pressure chamber forming portion 48 including a pressure accumulator container 18, which is a hollow case portion, a cylinder 27, and a piston portion 28. The pressure accumulator container 18 is made up of a cap 23 and a holder 24. Therefore, the pressure chamber forming portion 48 is a portion including the cap 23, the holder 24, the cylinder 27, and the piston portion 28. In other words, the space surrounded by the pressure chamber forming portion 48, which is made up of the cap 23, the holder 24, the cylinder 27, and the piston portion 28, is the pressure chamber 26. However, within the pressure chamber forming portion 48, the region of the pressure chamber 26 formed by the cylinder 27 is a portion above the position of the piston portion 28, which moves up and down. The pressure chamber 26 is filled with compressed gas, and this compressed gas presses the piston portion 28 to strike the nail (fastener) 78.

[0020] An annular seal member is attached to the outer peripheral surface of the piston portion 28 that faces the cylinder 27. This seal member abuts against the inner wall 27a of the cylinder 27, thereby preventing air from leaking from the cylinder 27. An X-ring 41 is provided on the piston portion 28 as a seal member that abuts against the inner wall 27a of the cylinder 27.

[0021] The nose portion 13 of the nail gun 10 is disposed inside and outside the cylinder case 19. The nose portion 13 has a bumper support portion 31, an injection portion 32, and a cylindrical portion 33. The bumper support portion 31 is cylindrical. A bumper 35 is disposed within the bumper support portion 31. The bumper 35 may be made of either synthetic rubber or silicone rubber. The bumper 35 has a guide hole 36. The center line A1 passes through the guide hole 36. The driver blade 29 is disposed within the guide hole 31a (see FIG. 2) of the bumper support portion 31 and within the guide hole 36.

[0022] The striking portion 12 can operate in a driving direction D1 and a return direction D2 along the center line A1. The driving direction D1 and the return direction D2 are opposite to each other. The driving direction D1 is the direction in which the piston portion 28 approaches the bumper 35. The return direction D2 is the direction in which the piston portion 28 moves away from the bumper 35. The striking portion 12 is constantly biased in the driving direction D1 by the gas pressure in the pressure chamber 26. Operation of the striking portion 12 in the driving direction D1 can be defined as descent. Operation of the striking portion 12 in the return direction D2 can be defined as ascent. The driving direction D1 is the same as the lower (one) side of the vertical direction (first direction) M1. The return direction D2 is the same as the upper (other) side of the vertical direction (first direction) M1.

[0023] The injection portion 32 is connected to the bumper support portion 31 and protrudes from the bumper support portion 31 in a direction along the center line A1. The injection portion 32 has an injection path 37 that is provided along the center line A1. The driver blade 29 can operate within the injection path 37 in a direction along the center line A1.

[0024] The electric motor 15 is also disposed within the motor case 21. The electric motor 15 has a rotor 39 and a stator 40. The stator 40 is attached to the motor case 21. The rotor 39 is rotatably supported by the motor case 21 via a bearing 38. The electric motor 15 is, for example, a brushless motor, and when a voltage is applied to the electric motor 15, the motor shaft 47 rotates together with the rotor 39 about a center line A2. The center line A2 is offset from the center line A1 in the left-right direction perpendicular to the up-down direction M1.

[0025] Furthermore, a reduction gear mechanism 16 is provided within the motor case 21. The reduction gear mechanism 16 includes a plurality of planetary gear mechanisms. A rotating shaft 46 connected to a motor shaft 47 is provided within the cylindrical portion 33. The rotating shaft 46 and the reduction gear mechanism 16 are concentrically arranged around the center line A2. The reduction gear mechanism 16 is disposed on a power transmission path from the electric motor 15 to the rotating shaft 46, and is a mechanism that reduces the rotation speed of the rotor 39 of the electric motor 15 and transmits the reduced speed to the winding mechanism 17.

[0026] The winding mechanism 17 converts the rotational force of the rotating shaft 46 into a force that urges the striking part 12 in the return direction D2. The winding mechanism 17 includes the driver blade 29, a plurality of racks 29a provided on the driver blade 29, a pinwheel 50 that serves as a rotating part, and a plurality of pins 50a provided on the pinwheel 50. When the pinwheel 50 rotates due to the driving force of the electric motor 15, the plurality of pins 50a of the pinwheel 50 sequentially engage with the plurality of racks 29a of the driver blade 29, and the striking part 12 including the driver blade 29 is pushed upward (in the return direction D2).

[0027] The nail gun 10 is also provided with a trigger 75 and a trigger switch 71. The trigger 75 and the trigger switch 71 are provided on the handle 20. The trigger switch 71 detects whether or not an operating force is applied to the trigger 75, and outputs a signal according to the detection result.

[0028] The power supply unit 14 has a housing case 76 and a battery housed in the housing case 76. The battery has a plurality of battery cells. These battery cells are secondary batteries that can be charged and discharged, and any known battery cell can be used, such as a lithium ion battery, a nickel-metal hydride battery, a lithium ion polymer battery, or a nickel-cadmium battery.

[0029] The electric motor 15 is operated by power supplied from the battery attached to the attachment portion 22 of the housing 11. A control unit 73 is housed inside the attachment portion 22. The control unit 73 includes a microcomputer composed of a CPU, ROM, RAM, etc., and controls the electric motor 15. Specifically, the control unit 73 changes the duty ratio of the motor current supplied to the electric motor 15 depending on the control mode. In other words, the control unit 73 controls the electric motor 15 using PWM (Pulse Width Modulation). Because the piston portion 28 moves when the electric motor 15 is operated, it can also be said that the control unit 73 controls the movement of the piston portion 28.

[0030] The nail gun 10 is also provided with a magazine 77. The magazine 77 is supported by the ejection unit 32 and the mounting unit 22. Nails (fasteners) 78 are loaded into the magazine 77. The magazine 77 has a feeder that sends the nails 78 in the magazine 77 to the ejection path 37. That is, the feeder moves the nails 78 in the magazine 77 forward in the front-to-rear direction N1. The ejection unit 32 is made of metal or synthetic resin. A push lever 79 is attached to the ejection unit 32. The push lever 79 can operate within a predetermined range along the center line A1 relative to the ejection unit 32. An elastic member (not shown) is provided to bias the push lever 79 in the direction along the center line A1. The elastic member is, for example, a metal spring that biases the push lever 79 in a direction away from the bumper support portion 31.

[0031] The push lever 79 can be switched between ON and OFF by being pressed against the mating material 30 by the operator. When the push lever 79 is pressed against the mating material 30 and moves upward against the bias of the spring, a signal is output. Furthermore, when the trigger 75 is operated by the operator, the trigger switch 71 built into the handle 20 is activated, and a signal for the driving operation is output. The push lever 79 and trigger 75 are operating parts that are operated by the operator.

[0032] The control unit 73 has two control modes for controlling the movement of the piston unit 28 by controlling the electric motor 15: a normal mode and a maintenance mode. In the normal mode, the piston unit 28 is positioned at the standby position shown in FIG. 4 during standby mode, when the control unit 73 receives both a signal generated by operating the push lever 79 and a signal generated by operating the trigger 75. In this standby mode, the control unit 73 supplies a motor current to the electric motor 15, activating the electric motor 15. This rotates the pinwheel 50, pushing up the driver blade 29 and moving the piston unit 28 from the standby position to the top dead center, which is located above (the other side of) the standby position in the vertical direction (first direction) M1. At the top dead center, the driver blade 29 attached to the piston unit 28 is disengaged from the pinwheel 50 and released. When the driver blade 29 is released, the air pressure from the pressure chamber 26 causes the striking unit 12, including the driver blade 29, to begin descending and move from the top dead center toward the bottom dead center, which is located below (one side of) the top dead center in the vertical direction (first direction) M1. Accordingly, the driver blade 29 strikes the nail 78, driving it out. The pinwheel 50 continues to rotate after striking the nail 78, and the piston unit 28 moves from the bottom dead center to the upper side (the other side of) the vertical direction (first direction) M1. When the piston unit 28 reaches the standby position, the pinwheel 50 stops rotating, and the piston unit 28 also stops. In the maintenance mode, when a predetermined operation is input by an operator during standby, the control unit 73 controls the electric motor 15 to move the piston unit 28 from the standby position to the bottom dead center and then wait at the bottom dead center.

[0033] Next, a sealing member attached to the piston portion 28 of the nail gun 10 will be described. As shown in FIG. 2 , the piston portion 28 includes a base member 28a having a sidewall 28b facing the inner wall 27a of the cylinder 27. The piston portion 28 further includes an X-ring (sealing member) 41 that seals between the sidewall 28b of the base member 28a and the inner wall 27a of the cylinder 27. That is, the X-ring 41 is attached to the base member 28a so as to be interposed between the sidewall 28b of the base member 28a and the inner wall 27a of the cylinder 27. In other words, the X-ring 41 is a member that prevents compressed gas in the pressure chamber 26 from leaking out from the gap between the sidewall 28b of the piston portion 28 and the inner wall 27a of the cylinder 27.

[0034] Slide rings 43 and 44 are attached to the side wall 28b of the base member 28a of the piston portion 28 in order to prevent the piston portion 28 from tilting when sliding.

[0035] Next, the pressure chamber forming portion 48 of the nail driver 10 will be described in detail. As described above, the pressure chamber forming portion 48 includes the cap 23, the holder 24, the cylinder 27, and the piston portion 28, and the pressure chamber 26 is a space surrounded by the pressure chamber forming portion 48, which is made up of the cap 23, the holder 24, the cylinder 27, and the piston portion 28. In this embodiment, a hole (first communication passage) 27b is provided in the cylinder 27 of the pressure chamber forming portion 48. The hole 27b is a passage that communicates between the inside and outside of the cylinder 27 when the cylinder 27 is in a predetermined state. In other words, the hole 27b is a passage that communicates between the inside and outside of the pressure chamber 26 when the cylinder 27 is in a predetermined position.

[0036] Here, the range of movement of the piston portion 28 will be described. The impact portion 12, including the piston portion 28, moves downward due to the pressure of the compressed air in the pressure chamber 26, thereby striking the nail 78. At this time, the piston portion 28 is pushed upward by the winding mechanism 17 and reaches the top dead center position shown in FIG. 3. Thereafter, as the driver blade 29 is released, the impact portion 12, including the driver blade 29 and piston portion 28, begins to descend due to the pressure of the air from the pressure chamber 26. The impact portion 12 then moves to the bottom dead center position (see FIG. 1), which is located below (one side of) the top dead center position in the vertical direction (first direction) M1, thereby striking the nail 78. After striking, the piston portion 28 is again pushed upward by the winding mechanism 17 and reaches the standby position shown in FIG. 4, where it enters a standby state.

[0037] In the present embodiment, the hole 27b provided in the cylinder 27 is located at a position that does not communicate with the pressure chamber 26, regardless of whether the piston portion 28 is at the top dead center position, the bottom dead center position, or the standby position. Specifically, as shown in FIG. 2 , when the piston portion 28 is located at the bottom dead center, the hole 27b is located lower (one side) in the vertical direction (first direction) M1 than the upper end (the other end in the first direction) of the piston portion 28. More specifically, the hole 27b is provided in the cylinder 27 so as to be located lower (one side) in the vertical direction (first direction) M1 than an X ring 41 attached to the piston portion 28. The side wall 28b of the piston portion 28 and the inner wall 27a of the cylinder 27 are sealed by the X ring 41. Therefore, by locating the hole 27b lower than the X ring 41, the pressure chamber 26 can be maintained in a sealed state. That is, the airtight state of the pressure chamber 26 is maintained regardless of whether the piston 28 is at the top dead center position, the bottom dead center position, or the standby position during the driving operation. In other words, the pressure chamber 26 formed by the pressure chamber forming portion 48 is not connected to the hole 27b.

[0038] On the other hand, as shown in Figure 5, when the piston portion 28 is positioned at the bottom dead center and the cylinder 27 is moved a predetermined amount upward (the other side) in the vertical direction (first direction) M1, the hole portion 27b also moves a predetermined amount upward, and the pressure chamber 26 and the hole portion 27b are connected.

[0039] In this embodiment, a state in which the pressure chamber 26 and the hole 27b are connected is defined as a first state, and a state in which the pressure chamber 26 and the hole 27b are not connected is defined as a second state, as shown in Fig. 2. With these definitions, the cylinder (pressure chamber forming portion 48) 27 of the nail driver 10 has the hole 27b that communicates between the inside and outside of the pressure chamber forming portion 48, and is switchable between a plurality of states (here, two states) including the first state in which the pressure chamber 26 and the hole 27b are connected and the second state in which the pressure chamber 26 and the hole 27b are not connected.

[0040] Therefore, in the nail gun 10, as shown in Figure 5, when the piston portion 28 is positioned at the bottom dead center by controlling the maintenance mode, the cylinder 27 can be moved a predetermined amount upward in the vertical direction M1 to enter a first state in which the pressure chamber 26 and the hole portion 27b are connected, and in this state, air is allowed to flow from the outside to the inside of the cylinder (pressure chamber forming portion 48) 27 to adjust the pressure inside the pressure chamber 26.

[0041] 2, in a second state in which the pressure chamber 26 and the hole 27b are not connected, the hole 27b is provided in the cylinder 27 so as to be located lower in the vertical direction M1 than the piston 28 which is located at the bottom dead center position. More specifically, the hole 27b is provided in the cylinder 27 so as to be located lower in the vertical direction M1 than the X ring 41 when the piston 28 is located at the bottom dead center position. The means for moving the cylinder 27 in the vertical direction M1 will be described later.

[0042] Next, referring to FIG. 5 , a valve provided in a passage communicating with the hole 27b in the first state in which the pressure chamber 26 and the hole 27b are connected will be described. In the nail gun 10, a cylindrical portion 34 is provided on the outer periphery of the bumper support portion 31 that supports the bumper 35. A passage (second communication passage) 34a that can communicate with the hole 27b of the cylinder 27 is formed within the cylindrical portion 34. Furthermore, a switching valve 49 is provided in the passage 34a. The switching valve 49 is, for example, a check valve. The cylindrical portion 34 protrudes from the bumper support portion 31 along the radial direction J1 of the cylinder 27 and extends in a direction along the center line A2. The bumper support portion 31, in which the cylindrical portion 34 is provided, is a part of the nose portion 13, and the cylinder 27 is attached to the nose portion 13. In other words, the cylindrical portion 34, in which the switching valve 49 is disposed, is provided in the nose portion 13. Therefore, in the nail driver 10, a passage 34a of the switching valve 49 for replenishing air to the pressure chamber 26 is provided at a position separated from the pressure chamber 26 formed by the pressure chamber forming portion 48. The cylindrical portion 34 is provided in the bumper support portion 31 of the nose portion 13 so as to be located above the piston portion 28 in the up-down direction M1 when the piston portion 28 is located at the bottom dead center.

[0043] As a result, by moving the cylinder 27 upward by a predetermined amount in the vertical direction M1 while the piston portion 28 is positioned at bottom dead center, the hole 27b provided in the cylinder 27 and the tubular portion 34 provided in the nose portion 13 are positioned at the same height (in the vertical direction M1), and the hole 27b and the passage 34a within the tubular portion 34 are able to communicate with each other. Furthermore, because the tubular portion 34 is positioned higher in the vertical direction M1 than the piston portion 28, the passage 34a within the tubular portion 34 is able to communicate with the pressure chamber 26 via the hole 27b. In this state, by opening the switching valve 49 for the passage 34a, the passage 34a, the hole 27b, and the pressure chamber 26 are able to communicate with each other. This allows an air inflow path K1 from the outside to be formed, allowing air to flow from the outside of the cylinder (pressure chamber forming portion 48) 27 into the inside, thereby adjusting the pressure within the pressure chamber 26. That is, air can be replenished into the pressure chamber 26 from the outside of the cylinder 27.

[0044] Next, the mounting state of the cylinder 27 and the nose portion 13 will be described. The cylinder 27 is a first case portion, and the nose portion 13 is a second case portion. The cylinder (first case portion) 27 can be mounted to the nose portion (second case portion) 13. The nose portion 13 supports a lower portion of the cylinder 27 and a bumper 35. Specifically, the nose portion 13 has a bowl-shaped bumper support portion 31, to which the cylinder 27 is mounted, and which supports the bumper 35.

[0045] Here, a means for moving the cylinder 27 in the up-down direction M1 will be described. In the present embodiment, as an example, the cylinder 27 is threadedly coupled to the nose portion 13. Specifically, as shown in FIG. 2 , the bumper support portion 31 and the cylinder 27 are threadedly coupled to each other by a threaded portion 45 including a female thread formed on the inner peripheral surface of the bowl-shaped bumper support portion 31 and a male thread formed on the outer peripheral surface of the cylinder 27. In the threaded coupling between the cylinder 27 and the bumper support portion 31, for example, by rotating the cylinder 27 and moving it downward (one side) in the up-down direction (first direction) M1 relative to the nose portion 13, the threaded coupling between the cylinder 27 and the nose portion 13 tightens, and the cylinder 27 moves downward relative to the nose portion 13. The downward movement of the cylinder 27 is stopped when the hole 27b of the cylinder 27 is positioned below the position of the X-ring 41 at the bottom dead center position of the piston portion 28, as shown in FIG. 2 . That is, when the hole 27b of the cylinder 27 is positioned below the position of the X-ring 41 at the bottom dead center of the piston 28, the rotation of the cylinder 27 is stopped and the tightening of the screws is stopped.

[0046] Meanwhile, the cylinder 27 with the screws tightened is rotated to loosen the screws of the threaded portion 45, and the cylinder 27 is moved upward by a predetermined amount until the hole 27b of the cylinder 27 and the tubular portion 34 of the nose portion 13 are at the same height, as shown in Figure 5, and the cylinder 27 is moved to a position where the hole 27b and the passage 34a inside the tubular portion 34 can communicate with each other, and the pressure in the pressure chamber 26 is adjusted in this state.

[0047] In this embodiment, the first attachment state is defined as the state in which the cylinder 27, with the threads of the threaded portion 45 tightened, is rotated to loosen the threads and move the cylinder 27 upward by a predetermined amount, until the hole 27b of the cylinder 27 and the tubular portion 34 of the nose portion 13 are at the same height, allowing communication between the hole 27b and the passage 34a within the tubular portion 34, as shown in Figure 5. In other words, the first attachment state is the attachment state of the cylinder 27 to the nose portion 13 in which pressure adjustment of the pressure chamber 26 is possible.

[0048] On the other hand, a state in which the threads of the threaded portion 45 are tightened by the rotation of the cylinder 27 and the hole 27b of the cylinder 27 is positioned below the position of the X-ring 41 at the bottom dead center position of the piston 28, as shown in Figure 2, is defined as a second attachment state. In other words, the attachment state of the cylinder 27 to the nose portion 13 in which the pressure of the pressure chamber 26 cannot be adjusted because the hole 27b of the cylinder 27 and the tubular portion 34 of the nose portion 13 are not at the same height is the second attachment state.

[0049] Therefore, the cylinder 27 can be attached to the nose portion 13 in a plurality of attachment states, including a first attachment state and a second attachment state. In this embodiment, the cylinder 27 can be attached to the nose portion 13 in two attachment states, the first attachment state and the second attachment state. As a result, the pressure chamber forming portion 48 including the cylinder 27 is in the first state in the first attachment state and in the second attachment state. Specifically, when the cylinder 27 is rotated to tighten the threads of the threaded portion 45 and the hole 27b of the cylinder 27 is positioned below the position of the X-ring 41 at the bottom dead center position of the piston portion 28 (second attachment state), as shown in FIG. 2 , the pressure chamber forming portion 48 is in the second state in which the pressure chamber 26 and the hole 27b of the cylinder 27 are not connected.

[0050] On the other hand, when the cylinder 27 with the screws tightened is rotated to loosen the screws of the threaded portion 45, and the cylinder 27 is moved upward by a predetermined amount until the hole portion 27b of the cylinder 27 and the tubular portion 34 of the nose portion 13 are at the same height (first mounting state), as shown in Figure 5, the pressure chamber forming portion 48 enters a first state in which the pressure chamber 26 and the hole portion 27b of the cylinder 27 are connected.

[0051] In other words, by rotating the cylinder 27 to loosen or tighten the threads of the threaded portion 45, the cylinder 27 can be moved up and down relative to the nose portion 13, thereby switching between communication and blockage between the hole portion 27b of the cylinder 27 and the pressure chamber 26.

[0052] Furthermore, by rotating the cylinder 27 from a tightened state to loosen the threaded portion 45 and moving the cylinder 27 upward in the vertical direction M1 relative to the nose portion 13, the attachment state of the cylinder 27 changes from the second attachment state to the first attachment state. Furthermore, by rotating the cylinder 27 to loosen the threaded portion 45 and moving the cylinder 27 upward relative to the nose portion 13, the cylinder 27 is released from the nose portion 13. In other words, by rotating the cylinder 27 so as to move the cylinder 27 in a direction (upward) away from the nose portion 13 and loosening the threaded portion 45, the hole 27b of the cylinder 27 and the pressure chamber 26 can be connected. In other words, by loosening the threaded portion 45 of the cylinder 27 from a tightened state, the cylinder 27 can be switched from the second attachment state to the first attachment state. This improves the workability of switching the mounting state of the cylinder 27 relative to the nose portion 13 .

[0053] 5, the cylindrical portion 34 of the bumper support portion 31 of the nose portion 13 is provided with a passage (second communication passage) 34a that is communicable with the pressure chamber 26 via the hole 27b of the cylinder 27 in a first state in which the pressure chamber 26 is connected to the hole 27b. The passage 34a includes an inner passage portion 34b that is communicable with the hole 27b, and an outer passage portion 34c that is located on the opposite side of the inner passage portion 34b in the radial direction J1 of the cylinder 27 and that is communicable with the outside. The passage 34a is provided with a switch valve 49 that is capable of switching between communication and blocking between the inner passage portion 34b and the outer passage portion 34c.

[0054] As a result, even when the pressure chamber 26 and the passage 34a of the cylindrical portion 34 are connected via the hole 27b during pressure adjustment of the pressure chamber 26, the outflow of air can be suppressed by the switching valve 49. Furthermore, since the O-ring 42 is provided around the passage 34a of the cylindrical portion 34, the outflow of air from around the cylindrical portion 34 can be suppressed.

[0055] Furthermore, a protruding portion (indicator) 27c is provided on the outer periphery of the cylinder 27 to indicate that the mounting state of the cylinder 27 relative to the nose portion 13 is a second mounting state in which the hole 27b of the cylinder 27 is positioned below the position of the X-ring 41 of the piston portion 28 and pressure adjustment of the pressure chamber 26 is not possible. The protruding portion 27c is formed in an annular shape and protrudes from the outer periphery of the cylinder 27. That is, when the cylinder 27 is rotated to tighten the threads of the threaded portion 45 and lower the cylinder 27 to the second mounting state so that the hole 27b of the cylinder 27 is positioned below the position of the X-ring 41 at the bottom dead center position of the piston portion 28, as shown in FIG. 2 , the cylinder 27 is lowered to such an extent that the protruding portion 27c of the cylinder 27 comes into contact with the upper end of the bumper support portion 31 of the nose portion 13. In other words, the protruding portion 27c is a marker for stopping the descent of the cylinder 27 when the cylinder 27 is lowered to switch from the first mounting state to the second mounting state, and by lowering the cylinder 27 to the extent that this protruding portion 27c contacts the upper end of the bumper support portion 31, the position of the cylinder 27 can be easily switched to the second mounting state.

[0056] In the present embodiment, in the nail driver 10, the pressure chamber forming portion 48 including the cylinder 27 can be switched between two states: a first state in which the pressure chamber 26 is connected to the hole 27b of the cylinder 27; and a second state in which the pressure chamber 26 is not connected to the hole 27b of the cylinder 27. That is, the pressure chamber forming portion 48 can be switched to the second state in which the pressure chamber 26 is not connected to the hole 27b of the cylinder 27. Specifically, the passage 34a of the switching valve 49 for replenishing air to the pressure chamber 26 is provided at a position separated from the pressure chamber 26 formed by the pressure chamber forming portion 48. This allows air to leak from the pressure chamber 26 through only one path around the piston portion 28. Therefore, the amount of air leaking from the pressure chamber 26 can be reduced in any of the states in which the piston portion 28 is positioned at the bottom dead center as shown in FIG. 2, the piston portion 28 is positioned at the top dead center as shown in FIG. 3, and the piston portion 28 is positioned in the standby position as shown in FIG. 4. In other words, the amount of air flowing out of the pressure chamber 26 can be reduced even during normal driving operations of the nailer 10 or during long-term storage.

[0057] This reduces the frequency with which the pressure chamber 26 needs to be refilled with air, which in turn reduces the frequency with which the nailing operation needs to be interrupted to refill the air. As a result, the convenience of the nail driver 10 can be improved.

[0058] Furthermore, even if gas leaks from the pressure chamber 26 due to long-term use of the nail gun 10, the housing 11 can be disassembled and the cylinder 27 can be moved upward by a predetermined amount while the piston 28 is positioned at bottom dead center by controlling the maintenance mode, thereby connecting the hole 27b of the cylinder 27, the pressure chamber 26, and the passage 34a of the tubular portion 34 of the nose portion 13. That is, by switching the pressure chamber forming portion 48 to a first state in which the pressure chamber 26 and the hole 27b of the cylinder 27 are connected, and operating the switching valve 49 in the tubular portion 34 to an open state, air can be replenished into the pressure chamber 26 via the hole 27b of the cylinder 27. This makes it easy to adjust the pressure in the pressure chamber 26.

[0059] Furthermore, since the passage 34a of the switching valve 49 for replenishing air to the pressure chamber 26 is located in a position separate from the pressure chamber 26, pressure from inside the pressure chamber 26 is not applied to the switching valve 49. This prevents air from leaking from the switching valve 49, making it unnecessary to attach a sealing cap member to prevent air leakage to the passage 34a where the switching valve 49 is installed. As a result, the number of parts in the nail driver 10 can be reduced.

[0060] Furthermore, because the passage 34a of the switching valve 49 for replenishing air into the pressure chamber 26 is located at a position separate from the pressure chamber 26, there is no need to install a valve member for replenishing air in the chamber base (holder 24), which is a component of the pressure chamber forming portion 48. This ensures uniformity in the thickness of the chamber base when molding the chamber base, and makes it possible to suppress molding defects that occur when molding the chamber base.

[0061] Next, a modification of this embodiment will be described.

[0062] In the modified nail driver 10 shown in Figures 6 to 9, a tubular portion 27d having a switching valve 49 therein for replenishing air to the pressure chamber 26 is provided on the outer periphery of the side wall of the cylinder 27. The tubular portion 27d is provided in a position in the up-down direction (first direction) M1 between the bottom dead center position of the piston portion 28 shown in Figure 6 and the standby position of the piston portion 28 shown in Figure 9. As shown in Figure 7, a passage 27e (first communication passage) communicating with the pressure chamber 26 is provided inside the tubular portion 27d, and a switching valve 49 is installed in this passage 27e as a check valve.

[0063] That is, the cylindrical portion 27d including the passage 27e (first communication passage) of the switching valve 49 is provided directly on the side wall of the cylinder 27, and the passage 27e is disposed between the bottom dead center position of the piston portion 28 and the standby position of the piston portion 28. In other words, the passage 27e is located below (one side) the X ring 41 in the vertical direction (first direction) M1 when the piston portion 28 is located at the standby position, and is located above (the other side) the X ring 41 in the vertical direction (first direction) M1 when the piston portion 28 is located at the bottom dead center position.

[0064] In this modification, in the maintenance mode, when a predetermined operation is input by the operator in the standby state, the control unit 73 controls the electric motor 15 to move the piston 28 from the standby position to the bottom dead center and then wait at the bottom dead center. In other words, in the maintenance mode, after striking the nail 78, the piston 28 stops below (one side of) the passage 27e (first communication passage) in the vertical direction (first direction) M1. More specifically, the piston 28 stops at a position where at least a portion of the piston 28 (the X ring 41) is located below (one side of) the passage 27e (first communication passage) in the vertical direction (first direction) M1. Therefore, when the piston 28 is positioned below the switching valve 49 by control in the maintenance mode as shown in FIG. 6 , the switching valve 49 can be opened to form the air inflow path K1 as shown in FIG. 7 without rotating the cylinder 27 as in the nail driver 10 shown in FIG. 1 . This allows air to be replenished into the pressure chamber 26, and pressure adjustment can be performed.

[0065] 6 to 9 , the pressure chamber forming portion 48 including the cylinder 27 can also be switched between two states: a first state in which the pressure chamber 26 is connected to the passage 27e of the cylinder 27, and a second state in which the pressure chamber 26 is not connected to the passage 27e of the cylinder 27. In this modification, the state in which the piston portion 28 is positioned at the bottom dead center position shown in FIG. 6 corresponds to the first state in which the pressure chamber 26 is connected to the passage 27e of the cylinder 27, and the state in which the piston portion 28 is positioned at the top dead center position shown in FIG. 8 and the state in which the piston portion 28 is positioned at the standby position shown in FIG. 9 correspond to the second state in which the pressure chamber 26 is not connected to the passage 27e of the cylinder 27. In other words, when the piston portion 28 is positioned at the top dead center position or the standby position, the pressure chamber forming portion 48 can be set to the second state in which the pressure chamber 26 is not connected to the passage 27e of the cylinder 27.

[0066] In the case of this modified example, when the piston portion 28 is positioned at the top dead center position or the standby position, the passage 27e is positioned below the piston portion 28, so that the path through which air leaks from the pressure chamber 26 can be limited to a single path around the piston portion 28.

[0067] Therefore, when the piston 28 is positioned at the top dead center position shown in Fig. 8 and when the piston 28 is positioned at the standby position shown in Fig. 9, the amount of air flowing out of the pressure chamber 26 can be reduced. In other words, the amount of air flowing out of the pressure chamber 26 can be reduced even during normal driving operations of the nail driver 10 or when the nail driver 10 is stored for a long period of time.

[0068] This reduces the frequency with which air needs to be replenished in the pressure chamber 26. As a result, the frequency with which the driving operation needs to be interrupted to replenish air can also be reduced, thereby improving the convenience of the nail driver 10 in the modified example.

[0069] In detail, when the piston portion 28 is positioned below the passage 27e of the cylinder 27 (bottom dead center, etc.), the pressure chamber 26 and the passage 27e of the cylinder 27 are connected, but when the piston portion 28 is positioned above the passage 27e of the cylinder 27 (standby position, top dead center, etc.), the pressure chamber 26 and the passage 27e of the cylinder 27 (switching valve 49) are isolated by the piston portion 28.

[0070] 1, the nail gun 10 of the modified example can also suppress air leakage from the switching valve 49 provided in the passage 27e of the cylinder 27. Note that the piston 28 is in the standby position when the electric motor 15 is not driven, and therefore the nail gun 10 is maintained in this state for a longer period of time than when the piston 28 is located at the bottom dead center. Therefore, simply isolating the switching valve 49 when the piston 28 is in the standby position can sufficiently achieve the effect of suppressing air leakage.

[0071] For example, in a nail gun in which a valve for refilling air is provided on a chamber base or the like, when the piston part is in the standby position, the pressure chamber and the valve are connected, which can lead to air leakage.

[0072] However, in the nail driver 10 of this modified example, when the piston 28 is positioned above the switching valve 49 (e.g., at the standby position or top dead center), the pressure chamber 26 and the switching valve 49 are isolated by the piston 28, thereby preventing air leakage from the switching valve 49 provided in the passage 27e of the cylinder 27. Furthermore, when the piston 28 is positioned at the standby position or top dead center, the pressure in the pressure chamber 26 is higher, which makes air leakage more likely to occur. Therefore, in the nail driver 10 of this modified example, as shown in FIGS. 8 and 9 , the pressure chamber 26 and the switching valve 49 are isolated from each other at positions of the piston 28 where the pressure in the pressure chamber 26 is higher. In other words, by positioning the switching valve 49 closer to the bottom dead center than the piston 28 at positions of the piston 28 where the pressure in the pressure chamber 26 is higher, air leakage through the switching valve 49 can be prevented. When an operator refills the pressure chamber 26 with compressed air, the piston portion 28 is stopped at the bottom dead center side by controlling the maintenance mode as shown in Figure 6, and the operator can perform the work via the switching valve 49.

[0073] The present invention is not limited to the above-described embodiment including the above-described modified examples, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the first communication passages such as the hole 27b and the passage 27e are provided in the cylinder 27, but the first communication passages may be provided in a chamber cover, a chamber base, or the like other than the cylinder 27.

[0074] 1 , instead of moving the cylinder 27 upward to connect the pressure chamber 26 and the passage 34a when the piston 28 is at the bottom dead center, the position of the hole 27b of the cylinder 27 is set to the position of the switching valve 49, and the bottom dead center position of the piston 28 is set to a position where the slide ring 43 of the piston 28 is at the same height as the hole 27b. In this state, the bumper 35 may be deformed so that the top of the bumper 35 moves downward, thereby moving the piston 28 downward and connecting the pressure chamber 26 and the passage 34a via the hole 27b of the cylinder 27.

[0075] In other words, by moving the piston portion 28 further downward from the bottom dead center position, it is possible to switch between a first state in which the pressure chamber 26 and the passage 34a of the switching valve 49 are connected, and a second state in which the pressure chamber 26 and the passage 34a of the switching valve 49 are not connected.

[0076] Furthermore, the passage in which the switching valve 49 is provided may be provided in a member other than the cylinder 27 constituting the first case portion. For example, a passage corresponding to the passage 34a may be provided in the holder 24, and the hole 27b of the cylinder 27 may be disposed in a range where the cylinder 27 and the holder 24 overlap in the radial direction J1, so that a configuration may be configured in which the cylinder 27 and the holder 24 are in a normal assembled state and the hole 27b and the passage of the holder 24 are not connected, and a first state in which the holder 24 has moved in the up / down direction (first direction) from the second state and the hole 27b and the passage of the holder 24 are connected.

[0077] Furthermore, in the above embodiment, the extension direction of the tubular portion 34 in which the switching valve 49 is installed, extending from the bumper support portion 31, was along the center line A2, but the extension direction of the tubular portion 34 may be in a direction other than along the center line A2 as long as it is the radial direction J1 of the cylinder 27.

[0078] 10... Nail gun (work machine), 11... Housing, 12... Striking portion, 13... Nose portion, 14... Power supply portion, 15... Electric motor, 16... Reduction mechanism, 17... Winding mechanism, 18... Pressure accumulator vessel, 19... Cylinder case, 20... Handle, 21... Motor case, 22... Mounting portion, 23... Cap, 24... Holder, 25... Head cover, 26... Pressure chamber, 27... Cylinder, 27a... Inner wall, 27b... Hole portion (first communication passage), 27c... Protruding portion (display portion), 27d... Cylindrical portion, 27e... Passage (first communication passage), 28... Piston portion, 28a... Base member, 28b... Side wall, 29... Driver blade, 29a... Rack, 30... Counterpart, 31... Bumper support portion, 31a... Guide hole, 32... Injection portion, 33... Cylindrical portion, 34... Cylindrical portion, 34a...passage (second communication passage), 34b...inner passage portion, 34c...outer passage portion, 35...bumper, 36...guide hole, 37...injection path, 38...bearing, 39...rotor, 40...stator, 41...X-ring (sealing member), 42...O-ring, 43, 44...slide ring, 45...threaded portion, 46...rotating shaft, 47...motor shaft, 48...pressure chamber forming portion, 49...switching valve, 50...pinwheel, 50a...pin, 71...trigger switch, 73...control portion, 75...trigger, 76...storage case, 77...magazine, 78...nail (fastener), 79...push lever, A1, A2...center line, D1...driving direction, D2...return direction, J1...radial direction, K1...inflow path, M1...up-down direction (first direction), N1...front-rear direction

Claims

1. A work machine having a pressure chamber forming portion including: a hollow first case portion including a cylindrical cylinder extending in a first direction; and a piston portion movable in the first direction inside the cylinder and cooperating with the first case portion to define a pressure chamber inside the first case portion, and moving to one side in the first direction due to the pressure of gas inside the pressure chamber, thereby striking a stopper; wherein the pressure chamber forming portion has a first communication passage connecting the inside and outside of the pressure chamber forming portion, and is switchable between a plurality of states including a first state in which the pressure chamber and the first communication passage are connected, and a second state in which the pressure chamber and the first communication passage are not connected.

2. A work machine as described in claim 1, comprising an operating unit operated by an operator, wherein when the operating unit is operated, the piston unit moves from a top dead center position to a bottom dead center position located on one side of the top dead center position in the first direction, thereby striking the stopper, and then moves from the bottom dead center position to the other side in the first direction and stops at a standby position, and the first communication passage is provided in the cylinder such that its position in the first direction is located between the standby position and the bottom dead center position.

3. A work machine as described in claim 2, further comprising a control unit for controlling the movement of the piston portion, the control unit having a first mode and a second mode as control modes for controlling the movement of the piston portion, in the first mode, after striking the stopper, the piston portion moves from the bottom dead center position to the other side in the first direction and stops at the standby position, and in the second mode, the piston portion stops on one side in the first direction from the first communicating passage.

4. A work machine as described in claim 3, wherein the piston portion includes a base member having a side wall and a sealing member that seals between the side wall of the base member and the inner wall of the cylinder, and the first communication passage is located on one side in the first direction of the sealing member when the piston portion is located in the standby position, and is located on the other side in the first direction of the sealing member when the piston portion is stopped in the second mode.

5. A work machine as described in claim 1, wherein the piston portion strikes the stopper by moving from a top dead center position to a bottom dead center position which is located on one side of the top dead center position in the first direction, and the first communication passage is provided in the cylinder so as to be located on the one side of the first direction of the piston portion which is located at the bottom dead center position in the second state.

6. A work machine as described in claim 5, wherein the piston portion includes a base member having a side wall and a sealing member that seals between the side wall of the base member and an inner wall of the cylinder, and the first communication passage is located to one side in the first direction of the sealing member when the piston portion is located at the bottom dead center position.

7. A work machine as described in claim 1, wherein the first communication passage is provided in the first case part, the work machine has a second case part to which the first case part is attached, the first case part is attachable to the second case part in a plurality of attachment states including a first attachment state and a second attachment state, and the pressure chamber forming part is in the first state in the first attachment state and in the second state in the second attachment state.

8. A work machine as described in claim 7, wherein the first case part changes from the second mounting state to the first mounting state by moving to the other side in the first direction relative to the second case part, and detaches from the second case part by further moving to the other side in the first direction.

9. The work machine according to claim 7, wherein the first case portion is screwed to the second case portion.

10. A work machine as set forth in claim 7, further comprising an indicator for indicating that the mounting state of said first case portion is said second mounting state.

11. A work machine as described in claim 7, further comprising a second communication passage provided in the second case portion and capable of communicating with the pressure chamber via the first communication passage in the first state, the second communication passage including an inner passage portion capable of communicating with the first communication passage and an outer passage portion located opposite the inner passage portion in the radial direction of the cylinder and capable of communicating with the outside, and a switching valve is provided in the second communication passage capable of switching between communication and blocking between the inner passage portion and the outer passage portion.

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