WO2012081589A1

WO2012081589A1 - Power tool

Info

Publication number: WO2012081589A1
Application number: PCT/JP2011/078830
Authority: WO
Inventors: 周祐伊藤
Original assignee: 株式会社マキタ
Priority date: 2010-12-16
Filing date: 2011-12-13
Publication date: 2012-06-21
Also published as: JP2012125898A

Abstract

[Problem] To provide a power tool having a gear-shift mechanism that contributes towards improving the smoothness of a gear-shift operation. [Solution] A power tool in which a tip tool (113) is driven and predetermined machining work is performed, the power tool having an input shaft (131), an output shaft (133) for driving the tip tool (113), and a first transmission path (P1) and a second transmission path (P2) for transmitting the rotary force from the input shaft (131) to the output shaft (133). The power tool is configured so that in a case in which the input shaft (131) is caused to rotate in a first direction, the rotary force in the first direction is transmitted via a first transmission path (P1) to the output shaft (133) at a predetermined transmission ratio; and in a case in which the input shaft (131) is caused to rotate in a second direction that is opposite to the first direction, the rotary force in the second direction is transmitted via a second transmission path (P2) to the output shaft (133) at a transmission ratio that is different from the transmission ratio of the first transmission path (P1). Switching the direction of rotation of the input shaft (131) causes the rotation speed of the output shaft (133) to switch while the direction of rotation of the output shaft is maintained.

Description

Power tools

The present invention relates to a power tool having a speed change mechanism.

Japanese Patent Application Laid-Open No. 59-192466 discloses an electric tool provided with a parallel shaft transmission mechanism. The parallel-shaft transmission mechanism described in the above publication is mounted on the drive shaft so that the first and second drive gears having different numbers of teeth are movable on the driven shaft parallel to the drive shaft so as to be movable in the long axis direction. First and second driven gears having different numbers of teeth, and the first and second driven gears are slid along the driven shaft for meshing engagement with the first and second drive gears. By switching, the rotational speed of the motor is shifted to two stages, high speed and low speed, and transmitted to the tip tool.

According to the conventional parallel shaft transmission mechanism described in the above publication, when the gear is shifted by changing the relative position of the driven gear with respect to the driving gear, the meshing engagement between the driving gear and the driven gear is difficult to perform smoothly. There is still room for improvement in terms of the smoothness of the shifting operation.

This invention is made in view of this point, and it aims at providing the power tool provided with the speed change mechanism which contributes to the improvement of the smoothness of speed change operation | movement.

To achieve the above object, according to a preferred embodiment of the present invention, a power tool that drives a tip tool to perform a predetermined machining operation is configured. The “predetermined processing operation” in the present invention is an operation of cutting wood or metal with a rotating saw blade or saw chain, an operation of polishing or grinding metal, stone or the like with a rotating sanding disk, or a diamond that rotates. Various machining operations such as drilling a relatively large diameter with a core drill, and trimming a hedge by reciprocating the upper and lower blades in a straight line in opposite directions are widely included.

In a preferred embodiment of the power tool according to the present invention, the power tool includes an input shaft, an output shaft that drives the tip tool, and a first transmission path and a second transmission path that transmit rotational force from the input shaft to the output shaft. When the input shaft is rotated in the first direction, the rotational force in the first direction is transmitted to the output shaft through the first transmission path at a predetermined transmission ratio, thereby causing the output shaft to move in the predetermined direction. When the input shaft is rotated in the second direction opposite to the first direction, the output shaft passes through the second transmission path at a transmission ratio different from the transmission ratio of the first transmission path. The rotational force in the second direction is transmitted, whereby the output shaft is configured to rotate in a predetermined direction. By switching the input shaft rotational direction, the output shaft maintains the rotational direction at a constant rotational speed. Switched.

According to the present invention, the rotation speed of the output shaft can be switched by switching the rotation direction of the input shaft. Therefore, it is possible to smoothly perform the operation for switching the rotation speed of the output shaft, that is, the speed change operation. In this case, each of the first transmission path and the second transmission path has a plurality of gears, and when the transfer direction of the input shaft is switched, the output shaft rotates while maintaining the meshing engagement of the plurality of gears. It is possible to adopt a configuration for switching the speed.

In a further form of the power tool according to the present invention, at least one one-way clutch is provided on each of the transmission paths of the first transmission path and the second transmission path. The one-way clutch of the first transmission path transmits only rotation in the first direction, and the one-way clutch of the second transmission path transmits only rotation in the second direction.

According to this aspect, as described above, the first transmission path when the rotation direction of the input shaft is switched by providing at least one one-way clutch on each of the transmission paths of the first transmission path and the second transmission path. It is possible to construct a speed change mechanism that can smoothly switch the transmission path between the transmission path and the second transmission path.

In a further form of the power tool according to the present invention, a first intermediate shaft provided separately from the input shaft and the output shaft, a second intermediate shaft integrated with the output shaft, and the input shaft are provided. A first gear, a second gear provided on the second intermediate shaft and constantly meshingly engaged with the first gear, and a first gear provided on the first intermediate shaft and meshingly engaged with the first gear at all times. Three gears, a fourth gear provided on the first intermediate shaft, and a fifth gear provided on the second intermediate shaft and meshingly engaged with the fourth gear at all times. The first transmission path includes a first gear, a second gear, and a second intermediate shaft. The second transmission path includes a first gear, a third gear, a first intermediate shaft, a fourth gear, a fifth gear, and a second intermediate shaft.

According to this aspect, the input shaft, the first intermediate shaft, and the second intermediate shaft that also serves as the output shaft, a total of three shafts, and a plurality of gears that transmit the rotational force between the shafts, It is the structure which always meshes each. For this reason, it solves the problem of strength such as generation of noise due to tooth interference, missing teeth or wear, when switching gear meshing, which can be seen in a conventional speed change mechanism that shifts gear meshing. Can do.

In a further embodiment of the power tool according to the present invention, first and third intermediate shafts provided separately from the input shaft and the output shaft, a second intermediate shaft integrated with the output shaft, and an input shaft A first gear provided, a second gear provided on the first intermediate shaft and constantly meshingly engaged with the first gear, a third gear provided on the first intermediate shaft, and a second intermediate A fourth gear that is provided on the shaft and is always meshed and engaged with the third gear, a fifth gear that is provided on the third intermediate shaft and is always meshed and engaged with the second gear, and a third intermediate shaft. And a sixth gear that is always meshed with and engaged with the fourth gear. The first transmission path includes a first gear, a second gear, a first intermediate shaft, a third gear, a fourth gear, and a second intermediate shaft. The second transmission path is configured by the first gear, the second gear, the fifth gear, the third intermediate shaft, the sixth gear, the fourth gear, and the second intermediate shaft.

According to this embodiment, the input shaft, the first and third intermediate shafts, and the second intermediate shaft that also serves as the output shaft, a total of four shafts, and a plurality of gears that transmit the rotational force between these shafts, The gears are always engaged with each other. For this reason, as in the case of the three-axis configuration described above, the occurrence of abnormal noise due to tooth interference, missing teeth, or the like found in conventional transmission mechanisms that change gear engagement by changing gear engagement. It is possible to solve strength problems such as wear.

In a further form of the power tool according to the present invention, a one-way clutch is provided between a predetermined gear other than the first gear and the intermediate shaft, and the one-way clutch is configured to rotate the shaft and the gear in one direction. Both are integrated, and the rotation in the other direction is configured to allow relative rotation between the two. Thereby, the transmission path can be smoothly switched by switching the rotation direction of the input shaft.

In the further form of the power tool which concerns on this invention, switching of the rotation direction of an input shaft is performed by manual operation. The “manual operation” in this embodiment includes a mode in which the operation amount of the operation member is changed to switch the rotation direction of the input shaft, a mode in which the operation direction of the operation member is switched to switch the rotation direction of the input shaft, and the like.
According to this aspect, by using a switching method by manual operation, when performing a predetermined machining operation using a power tool, the operator can arbitrarily change the speed according to the work situation or the like.

In a further embodiment of the power tool according to the present invention, the switching of the rotation direction of the input shaft is automatic switching. “Automatic switching” in this form is typically performed according to the load acting on the tip tool. For example, it is switched to the high speed side when the load is low, and is switched to the low speed side when the load is high. For this reason, if the drive source of the power tool is, for example, an electric motor, it is performed according to the current value or the rotation speed of the electric motor, thereby avoiding the tip tool from being driven at high speed in a high load state. The electric motor can be prevented from being burned out.

According to the present invention, a power tool provided with a speed change mechanism that contributes to improvement in smoothness of speed change operation is provided. Other characteristics, operations, and effects of the present invention can be readily understood with reference to the present specification, claims, and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view partially including a cross section showing an overall configuration of a slide circular saw according to a first embodiment of the present invention. It is a top view which shows the whole structure of a slide circular saw. It is sectional drawing which shows the structure of the speed change mechanism mounted in the slide circular saw. It is a figure which shows the transmission mechanism of a slide circular saw, and shows the state switched to the high speed side. It is a figure which shows the transmission mechanism of a slide circular saw, and shows the state switched to the low speed side. It is a side view which includes a cross section in part which shows the whole structure of the chain saw which concerns on the 2nd Embodiment of this invention. It is sectional drawing which shows the structure of the speed change mechanism mounted in the chain saw. It is a figure which shows the transmission mechanism of a chain saw, and shows the state switched to the high speed side. It is a figure which shows the transmission mechanism of a chain saw, and shows the state switched to the low speed side.

The configurations and methods according to the above and the following description are separately or separately from other configurations and methods in order to realize the manufacture and use of the “power tool” according to the present invention and the use of the components of the “power tool”. Can be used in combination. Exemplary embodiments of the present invention include these combinations and will be described in detail with reference to the accompanying drawings. The following detailed description is only to teach those skilled in the art with detailed information to implement preferred embodiments of the invention, and the scope of the invention is not limited by the detailed description, but is limited by the scope of the claims. It is determined based on the description. For this reason, combinations of configurations and method steps in the following detailed description are not all essential to implement the present invention in a broad sense, but are described in detail with reference numerals in the accompanying drawings. However, only representative embodiments of the present invention are disclosed.

(First embodiment of the present invention)
Hereinafter, a sliding circular saw according to a first embodiment of the present invention will be described with reference to FIGS. The present embodiment will be described when applied to an electric slide circular saw as an example of a power tool. 1 and 2 show the overall configuration of the slide circular saw 101. FIG. As shown in FIGS. 1 and 2, the slide circular saw 101 generally includes a circular saw body portion 103 as a tool body, a base 120, and a connecting portion 125 that connects the circular saw body portion 103 and the base 120. Configured as the subject.

As shown in FIGS. 1 to 3, the circular saw body 103 includes a housing 105 that houses the drive motor 111 and the transmission mechanism 130, a blade case 106 that covers the upper half of the blade 113, and a safety cover that covers the lower half of the blade 113. 107, mainly composed of a hand grip 109 gripped by an operator, and connected to the connecting portion 125 so as to be swingable in the vertical direction about the swing support point 104. The housing 105, the blade case 106, and the hand grip 109 are connected to each other and formed integrally. The safety cover 107 is pivoted upward in conjunction with the downward swinging motion of the circular saw body 103 to open the lower half of the blade 113, so that the circular saw body 103 swings upward. Closes by interlocking and turning downward. The drive motor 111 is driven by an AC power source and rotationally drives the blade 113 via the speed change mechanism 130.

The drive motor 111 is a reversible motor capable of switching the rotation direction, and the rotation direction is switched according to the load acting on the blade 113. For example, a change in the current value or the rotation speed of the drive motor 111 is detected by a predetermined sensor, and the rotation direction is switched when a detection value detected by the sensor detects a predetermined threshold value. The drive motor 111 corresponds to the “motor” in the present invention.

The base 120 has a turntable 121 on which a work material can be placed. The base 120 has a sleeve 123, and the sleeve 123 is attached to a slide rod 127 fixed to the connecting portion 125 so as to be relatively movable in the front-rear direction (left-right direction in FIG. 1).

The operator pulls the trigger 109a provided on the handgrip 109, grips the handgrip 109 and tilts the circular saw body 103 downward while the drive motor 111 is energized and driven to rotate the blade 113. In addition to the operation, the work piece placed on the turntable 121 can be cut by sliding the circular saw body 103 together with the connecting portion 125 backward (to the connecting portion side) with respect to the base 120. .

Next, the speed change mechanism 130 will be described with reference to FIGS. The speed change mechanism 130 according to the present embodiment includes an input shaft 131 that is coaxially connected to or integrally formed with the motor shaft 112 of the drive motor 111, a blade mounting shaft 133 as an output shaft to which the blade 113 is mounted, The intermediate shaft 135 disposed on the opposite side of the blade mounting shaft 133 across the input shaft 131 is a parallel three-shaft type disposed in parallel to each other, and switches the rotation direction of the drive motor 111, that is, the rotation direction of the input shaft 131 By switching, the power transmission path is configured as a two-stage switching type that switches from high speed low torque to low speed high torque. The input shaft 131 corresponds to the “input shaft” in the present invention, the blade mounting shaft 133 corresponds to the “output shaft” and the “second intermediate shaft” in the present invention, and the intermediate shaft 135 corresponds to the “input shaft” in the present invention. This corresponds to the “first intermediate shaft”. In the following description, the blade mounting shaft 133 is referred to as an output shaft. Further, when the input shaft 131 is rotated in one direction is referred to as normal rotation, and when the input shaft 131 is rotated in the other direction is referred to as reverse rotation. The forward rotation of the input shaft 131 corresponds to the “first direction” in the present invention, and the reverse rotation of the input shaft 131 corresponds to the “second direction” in the present invention.

The speed change mechanism 130 has a first power transmission path P1 (see FIG. 4) through which the rotational force of the input shaft 131 is transmitted from the first gear 137 to the output shaft 133 via the second gear 139, and the rotational force of the input shaft 131. A second power transmission path P2 (see FIG. 5) is transmitted from the first gear 137 to the output shaft 133 through the third gear 141, the intermediate shaft 135, the fourth gear 143, and the fifth gear 145. The first power transmission path P1 is determined as a high-speed and low-torque power transmission path determined by the gear ratio (reduction ratio) between the first gear 137 and the second gear 139, and the second power transmission path P2 It is defined as a low-speed high-torque power transmission path determined by the gear ratio (reduction ratio) between the first gear 137 and the third gear 141 and the gear ratio (reduction ratio) between the fourth gear 143 and the fifth gear 145. . The first power transmission path P1 and the second power transmission path P2 are indicated by thick lines with arrows. Note that the input shaft 131, the output shaft 133, and the intermediate shaft 135 are rotatably supported by the housing 105 via bearings 131a, 133a, and 135a, respectively.

The first gear 137 as a drive gear is formed integrally with the input shaft 131. The second gear 139 is attached to the output shaft 133 via the first one-way clutch 151, and is always meshed and engaged with the first gear 137. The fifth gear 145 is fixed to the distal end side (blade 113 side) on the output shaft 133 via a key 155. The third gear 141 is fixed to the intermediate shaft 135 via the key 157, is disposed on the opposite side of the second gear 139 with the first gear 137 interposed therebetween, and is always meshed and engaged with the first gear 137. The The fourth gear 143 is attached to the tip end side (blade 113 side) on the intermediate shaft 135 via the second one-way clutch 153, and is always meshed with and engaged with the fifth gear 145.

The first one-way clutch 151 and the second one-way clutch 153 are configured such that both the shaft and the gear rotate in one direction, and both rotate in the other direction and allow the relative rotation of both. The That is, the first one-way clutch 151 on the output shaft 133 is configured to transmit the rotational force of the second gear 139 to the output shaft 133 when the input shaft 131 rotates in the forward direction, but not when the input shaft 131 rotates in the reverse direction. Yes. On the other hand, the second one-way clutch 153 on the intermediate shaft 135 is configured not to transmit the rotational force of the intermediate shaft 135 to the fourth gear 143 when the input shaft 131 rotates forward, but to transmit it when the input shaft 131 rotates reversely. Yes.

The transmission mechanism 130 according to the present embodiment is configured as described above. Therefore, when the drive motor 111 is driven to rotate in order to cut the workpiece, the rotational force of the drive motor 111 is transmitted to the output shaft 133 via the first power transmission path P1. That is, the rotational force of the input shaft 131 is transmitted to the output shaft 133 via the first gear 137, the second gear 139, and the first one-way clutch 151, and the blade 113 is rotationally driven at high speed and low torque. At this time, the third gear 141 meshingly engaged with the first gear 131 and the intermediate shaft 135 connected to the third gear 141 and the key 157 are also rotated. However, the intermediate shaft 135 is rotated by the action of the second one-way clutch 153. To the fourth gear 143 is not transmitted. Note that the rotation direction of the output shaft 133 at this time is opposite to the rotation direction of the drive motor 111.

On the other hand, when the drive motor 111 is driven in reverse, the rotational force is not transmitted from the second gear 139 to the output shaft 133 by the action of the first one-way clutch 151, and conversely by the action of the second one-way clutch 153. The rotational force of the intermediate shaft 135 is transmitted to the fourth gear 143. That is, the rotational force of the input shaft 131 is transmitted to the output shaft 133 through the first gear 137, the third gear 141, the intermediate shaft 135, the second one-way clutch 153, the fourth gear 143, and the fifth gear 145, and the blade 113. Is driven to rotate at low speed and high torque. At this time, the rotation direction of the output shaft 133 is the same as the rotation direction of the drive motor 111. As described above, when the rotation direction of the drive motor 111 is switched from forward rotation to reverse rotation, the transmission path of the rotational force of the drive motor 111 is switched from the first power transmission path P1 to the second power transmission path P2. The rotation direction of 133 does not change. That is, even if the rotation direction of the input shaft 131 is switched, the rotation direction of the output shaft 133 is kept constant.

The cutting work of the workpiece by the blade 113 starts at a high speed and a low torque using the first power transmission path P1 in which the drive motor 111 is driven to rotate forward. Then, when the cutting operation proceeds and the load acting on the blade 113 reaches a predetermined magnitude (when the current value of the drive motor 111 or the rotation speed reaches a predetermined threshold), the drive motor 111 Is switched to the reverse drive to switch to the second power transmission path P2. Thus, the driving of the blade 113 can be automatically switched from the driving with the high speed and low torque to the driving with the low speed and high torque. When the drive motor 111 is switched from forward rotation to reverse rotation, the drive motor 111 is braked. At this time, since the blade 113 tries to continue rotating due to inertia, the first one-way clutch 151 is idled. Become. For this reason, the rotation of the blade 113 from the high speed and low torque to the low speed and high torque is conveniently switched.

As described above, according to the present embodiment, the transmission path of the rotational force is reduced at high speed by switching the rotation direction of the drive motor 111 according to the load acting on the blade 113 for the power transmission path of the drive motor 111. The first power transmission path P1 for torque can be automatically switched to the second power transmission path P2 for low speed and high torque.

In the present embodiment, the second power is transmitted from the first power transmission path P1 in a state where the meshing engagement of each gear in the gear train constituting the transmission mechanism 130 is maintained, that is, the position of each gear is fixed. Since the transmission path P2 can be switched, the speed change operation can be performed smoothly, and the smoothness of the speed change operation can be improved.

(Second embodiment of the present invention)
Next, a second embodiment of the present invention will be described with reference to FIGS. The present embodiment is applied to a rechargeable chain saw 201 used for cutting and pruning operations. The chain saw 201 corresponds to the “power tool” in the present invention. FIG. 6 shows the overall configuration of the chain saw 201. The chain saw 201 is mainly composed of a chain saw body 203, a guide bar 220 having one end fixed to the chain saw body 203, and a saw chain 213 arranged in a circular shape along the guide bar 220. The machine body is constituted by the chain saw body 203. The saw chain 213 corresponds to the “tip tool” in the present invention.

The chain saw body 203 is mainly composed of a housing 205 (see FIG. 7) that houses the drive motor 211 and the speed change mechanism 230, and a hand grip 209 that is integrally provided in the housing 205 and is gripped by an operator. The handgrip 209 is provided with a trigger 209a that can be pulled by a finger to energize and drive the drive motor 211, and the end of the handgrip 209 in the long axis direction (the left end in FIG. 6) of the drive motor 211 is provided. A rechargeable battery pack 210 serving as a power source is attached. The saw chain 213 includes a drive-side sprocket 215 provided on the base side of the guide bar 220 (connection side with the chain saw body 203) and a driven-side sprocket provided on the tip side of the guide bar 220 (not shown for convenience). ) In a circular fashion. Then, the drive motor 211 is rotationally driven through the speed change mechanism 230, and the rotational motion is guided by the saw chain groove formed in the guide bar 220.

As the drive motor 211, a reversible motor capable of switching the rotation direction is used as in the first embodiment described above, and in this embodiment, the rotation direction can be arbitrarily switched by an operator's manual operation. It can be configured. The drive motor 211 corresponds to the “motor” in the present invention. The rotation direction of the drive motor 211 can be switched by, for example, a pull-in depth switching method in which the pull-in depth (pulling operation amount) of the trigger 209a as the operation member is changed stepwise.

Next, the speed change mechanism 230 will be described with reference to FIGS. The speed change mechanism 230 according to the present embodiment includes an input shaft 231 coaxially connected to or integrally formed with the motor shaft 212 of the drive motor 211 and an output shaft to which a drive-side sprocket 215 that drives the saw chain 213 is attached. The first and second

intermediate shafts

235 and 236 disposed between the input shaft 231 and the sprocket mounting shaft 233 are configured as a parallel four-shaft type in which the sprocket mounting shaft 233 is arranged in parallel. Then, by switching the rotation direction of the drive motor 211, that is, by switching the rotation direction of the input shaft 231, the power transmission path is configured as a two-stage switching type that switches from high speed low torque to low speed high torque.

The input shaft 231 corresponds to the “input shaft” in the present invention, the sprocket mounting shaft 233 corresponds to the “output shaft” and the “second intermediate shaft” in the present invention, and the first intermediate shaft 235 corresponds to the present invention. Corresponds to the “first intermediate shaft”, and the second intermediate shaft 236 corresponds to the “third intermediate shaft” in the present invention. In the following description, the sprocket mounting shaft 233 is referred to as an output shaft. Further, when the input shaft 231 is rotated in one direction is referred to as normal rotation, and when the input shaft 231 is rotated in the other direction is referred to as reverse rotation. The forward rotation of the input shaft 231 corresponds to the “first direction” in the present invention, and the reverse rotation of the input shaft 231 corresponds to the “second direction” in the present invention.

The transmission mechanism 230 transmits a first power transmission in which the rotational force of the input shaft 231 is transmitted from the first gear 237 to the output shaft 233 via the second gear 239, the first intermediate shaft 235, the third gear 241 and the fourth gear 243. The path P1 (see FIG. 8) and the rotational force of the input shaft 231 are output from the first gear 237 through the second gear 239, the fifth gear 245, the second intermediate shaft 236, the sixth gear 247 and the fourth gear 243. A second power transmission path P <b> 2 (see FIG. 9) that is transmitted to 233 is provided. Then, high-speed and low-torque power transmission determined by the gear ratio (reduction ratio) of the first gear 237 and the second gear 239 and the gear ratio of the third gear 241 and the fourth gear 243 for the first power transmission path P1. The second power transmission path P2, the gear ratio (reduction ratio) between the first gear 237 and the second gear 239, the gear ratio (reduction ratio) between the second gear 239 and the fifth gear 245, and the sixth It is defined as a low-speed and high-torque power transmission path determined by the gear ratio between the gear 247 and the fourth gear 243. The first power transmission path P1 and the second power transmission path P2 are indicated by thick lines with arrows. The input shaft 231, the output shaft 233, the first intermediate shaft 235, and the second intermediate shaft 236 are rotatably supported by the housing 205 via

bearings

231a, 233a, 235a, and 236a, respectively.

The first gear 237 as a drive gear is formed integrally with the input shaft 231. The second gear 239 is fixed to the first intermediate shaft 235 by a key 255 and is always meshed and engaged with the first gear 237. The third gear 241 is attached to the first intermediate shaft 235 via the first one-way clutch 251. The fourth gear 243 is fixed to the output shaft 233 by a key 257 and is always meshed with and engaged with the third gear 241. The fifth gear 245 is attached to the second intermediate shaft 236 via the second one-way clutch 253, and is always meshed with and engaged with the second gear 239. The sixth gear 247 is fixed to the second intermediate shaft 236 by a key 259, and is always meshed and engaged with the fourth gear 243.

The first one-way clutch 251 and the second one-way clutch 253 are configured such that both the shaft and the gear are rotated in one direction and the relative rotation of the both is allowed in the other direction. The That is, the first one-way clutch 251 on the first intermediate shaft 235 transmits the rotational force of the first intermediate shaft 235 to the third gear 241 when the input shaft 231 rotates in the forward direction, but does not transmit it when the input shaft 231 rotates in the reverse direction. It is configured. On the other hand, the second one-way clutch 253 on the second intermediate shaft 236 does not transmit the rotational force of the fifth gear 245 to the second intermediate shaft 236 when the input shaft 231 rotates forward, but transmits it when the input shaft 231 rotates reversely. It is configured.

The transmission mechanism 230 according to the present embodiment is configured as described above. Therefore, when the drive motor 211 is driven to rotate in order to cut the workpiece, the rotational force of the drive motor 211 is transmitted to the output shaft 233 via the first power transmission path P1. That is, the rotational force of the input shaft 231 is transmitted to the output shaft 233 via the first gear 237, the second gear 239, the first intermediate shaft 235, the first one-way clutch 251, the third gear 241 and the fourth gear 243, The saw chain 213 is driven to rotate at high speed and low torque. At this time, the fifth gear 245 engaged with and engaged with the second gear 239 is also rotated, but the second one-way clutch 253 acts to transmit the rotational force from the fifth gear 245 to the second intermediate shaft 236. I will not. At this time, the rotation direction of the output shaft 233 is the same as the rotation direction of the drive motor 211.

On the other hand, when the drive motor 211 is driven in reverse, the first one-way clutch 251 does not transmit the rotational force from the first intermediate shaft 235 to the third gear 241, and conversely the second one-way clutch 253 works. Thus, the rotational force of the fifth gear 245 is transmitted to the second intermediate shaft 236. That is, the rotational force of the input shaft 231 passes through the first gear 237, the second gear 239, the fifth gear 245, the second one-way clutch 253, the second intermediate shaft 236, the sixth gear 247, and the fourth gear 243. 233, the saw chain 213 is rotationally driven at a low speed and a high torque. At this time, the rotation direction of the output shaft 233 is opposite to the rotation direction of the drive motor 211. As described above, when the rotation direction of the drive motor 211 is switched from normal rotation to reverse rotation, the transmission path of the rotational force of the drive motor 211 is switched from the first power transmission path P1 to the second power transmission path P2. The rotation direction of 233 does not change. That is, even if the rotation direction of the input shaft 231 is switched, the rotation direction of the output shaft 233 is kept constant.

In this embodiment, as described above, the rotation direction of the drive motor 211 can be switched by manual operation of the trigger 209a by the operator. Therefore, when a worker performs a predetermined machining operation using a power tool, the saw chain 213 is driven at a high speed and a low torque using the first power transmission path P1 according to the work situation, and the second The cutting operation can be performed by arbitrarily switching between driving at low speed and high torque using the power transmission path P2.

Further, according to the present embodiment, as in the first embodiment described above, the meshing engagement of each gear in the gear train constituting the transmission mechanism 230 is maintained, that is, the position of each gear is fixed. Since it is possible to switch between the first power transmission path P1 and the second power transmission path P2, the speed change operation can be performed smoothly, and the smoothness of the speed change operation can be improved.

In the first embodiment applied to the slide circular saw 101, the automatic transmission in which the power transmission path of the speed change mechanism 130 is automatically switched according to the load acting on the blade 113 has been described. As described in the embodiment, the first power transmission path P1 and the second power transmission path P2 may be arbitrarily switched by a manual operation. On the other hand, in the second embodiment applied to the chain saw 201, the power transmission path of the speed change mechanism 230 is configured to be arbitrarily switchable by manual operation, but this is applied to the saw chain 213 as in the first embodiment. It is good also as a structure which carries out automatic transmission according to the load to perform.

Further, in the case of automatic transmission, a method of detecting a mechanical displacement (strain) of a member involved in power transmission with a strain gauge instead of a method of detecting a change in the current value or rotation speed of the drive motor 111 with a sensor. And the rotation direction of the

drive motors

111 and 211 may be switched when the detection value by the strain gauge detects a predetermined threshold value.

In the above-described embodiment, the electric slide circular saw 101 and the rechargeable chain saw 201 have been described as examples of the power tool. However, the embodiment is not limited thereto. Even a circular saw can be applied to a circular saw that uses a battery instead of an AC power supply, or a tabletop slide circular saw as shown in the figure, a tabletop circular saw, or a handheld circular saw. It can be applied to any of the above. Further, it can be applied to cutting tools other than circular saws and chain saws, for example, electric cutters, and can be applied to cutting tools in which the tip tool performs linear reciprocating motion such as reciprocating saws and jigsaws. . Furthermore, power tools other than cutting tools, such as sanding disks and grinders that grind or grind workpieces with a rotating sanding disk or grindstone, or drivers and wrench used for tightening operations, or various drills that perform drilling operations Furthermore, the present invention can be widely applied to various power tools such as a hedge trimmer in which two upper and lower blades are reciprocated linearly in opposite directions to perform hedge cutting work and the like.

101 slide circular saw (power tool)
103 Circular saw body (Power tool body)
104 Oscillating fulcrum 105 Housing 106 Blade case 107 Safety cover 109 Hand grip 109a Trigger 111 Drive motor (motor)
112 motor shaft 113 blade 120 base 121 turntable 123 sleeve 125 connecting portion 127 slide rod 130 transmission mechanism 131 input shaft 131a bearing 133 output shaft (second intermediate shaft)
133a Bearing 135 Intermediate shaft (first intermediate shaft)
135a Bearing 137 First gear 139 Second gear 141 Third gear 143 Fourth gear 145 Fifth gear 151 First one-way clutch 153 Second one-way clutch 155 Key 157 Key 201 Rechargeable chain saw (power tool)
203 Chain saw body 205 Housing 209 Hand grip 209a Trigger 210 Battery pack 211 Drive motor (motor)
212 Motor shaft 213 Saw chain (tip tool)
215 Drive-side sprocket 220 Guide bar 230 Transmission mechanism 231 Input shaft 231a Bearing 233 Output shaft (second intermediate shaft)
233a Bearing 235 First intermediate shaft (first intermediate shaft)
235a Bearing 236 Second intermediate shaft (third intermediate shaft)
236a bearing 237 first gear 239 second gear 241 third gear 243 fourth gear 245 fifth gear 247 sixth gear 251 first one-way clutch 253 second one-way clutch 255 key 257 key 259 key

Claims

A power tool that drives a tip tool to perform a predetermined machining operation,
An input shaft, an output shaft that drives the tip tool, and a first transmission path and a second transmission path that transmit rotational force from the input shaft to the output shaft,
When the input shaft is rotated in the first direction, the rotational force in the first direction is transmitted to the output shaft at a predetermined transmission ratio via the first transmission path, whereby the output shaft is When the input shaft is configured to be rotated in a predetermined direction and the input shaft is rotated in a second direction opposite to the first direction, the transmission ratio of the first transmission path is determined via the second transmission path. The rotational force in the second direction is transmitted to the output shaft at different transmission ratios, whereby the output shaft is configured to rotate in the predetermined direction, and by switching the rotational direction of the input shaft, A power tool characterized in that the rotation speed of the output shaft is switched while maintaining the rotation direction constant.
The power tool according to claim 1,
Each of the first transmission path and the second transmission path has a plurality of gears,
A power tool characterized in that when the rotation direction of the input shaft is switched, the rotation speed of the output shaft is switched while maintaining the meshing engagement of the plurality of gears.
The power tool according to claim 1 or 2,
At least one one-way clutch is provided on each of the transmission paths of the first transmission path and the second transmission path,
The one-way clutch of the first transmission path is configured to transmit only the rotation in the first direction, and the one-way clutch of the second transmission path is configured to transmit only the rotation in the second direction. Power tool characterized by
The power tool according to claim 3,
A first intermediate shaft provided separately from the input shaft and the output shaft;
A second intermediate shaft integrated with the output shaft;
A first gear provided on the input shaft;
A second gear provided on the second intermediate shaft and meshingly engaged with the first gear at all times;
A third gear provided on the first intermediate shaft and meshingly engaged with the first gear at all times;
A fourth gear provided on the first intermediate shaft;
A fifth gear provided on the second intermediate shaft and meshingly engaged with the fourth gear at all times;
Have
The first transmission path is configured by the first gear, the second gear, and a second intermediate shaft,
The power tool, wherein the second transmission path is constituted by the first gear, the third gear, the first intermediate shaft, the fourth gear, the fifth gear, and the second intermediate shaft.
The power tool according to claim 3,
First and third intermediate shafts provided separately from the input shaft and the output shaft;
A second intermediate shaft integrated with the output shaft;
A first gear provided on the input shaft;
A second gear provided on the first intermediate shaft and meshingly engaged with the first gear at all times;
A third gear provided on the first intermediate shaft;
A fourth gear provided on the second intermediate shaft and meshingly engaged with the third gear at all times;
A fifth gear provided on the third intermediate shaft and meshingly engaged with the second gear at all times;
A sixth gear provided on the third intermediate shaft and meshingly engaged with the fourth gear at all times;
Have
The first transmission path is configured by the first gear, the second gear, the first intermediate shaft, the third gear, the fourth gear, and the second intermediate shaft,
The second transmission path is constituted by the first gear, the second gear, the fifth gear, the third intermediate shaft, the sixth gear, the fourth gear, and the second intermediate shaft. tool.
The power tool according to claim 4 or 5,
The one-way clutch is provided between a predetermined gear other than the first gear and the intermediate shaft, and the rotation of the intermediate shaft and the gear in one direction is integrated and the rotation in the other direction. Is a power tool characterized by allowing the relative rotation of the two.
The power tool according to any one of claims 1 to 6,
The power tool according to claim 1, wherein the rotation direction of the input shaft is switched by a manual operation.
The power tool according to claim 7,
A manually operable operation member for energizing and driving the motor;
Switching the direction of rotation of the input shaft is performed by changing an operation amount of the operation member.
The power tool according to any one of claims 1 to 6,
The power tool according to claim 1, wherein the rotation direction of the input shaft is automatically switched.
The power tool according to claim 9, wherein
Having a sensor for detecting the current value or the rotational speed of the motor;
Switching the direction of rotation of the input shaft is performed when a detection value detected by the sensor reaches a predetermined threshold value.