Patent Grant
11318596
The present application claims priority to Japanese patent application nos. 2019-192325, 2019-192326, 2019-192327, and 2019-192328, all of which were filed on Oct. 21, 2019 and the contents of all of which are hereby fully incorporated herein by reference.
The present disclosure generally relates to power tools having a hammer mechanism, such as a rotary hammer or a hammer drill, which are configured to linearly reciprocally drive (axially hammer) a tool accessory to perform a hammering operation and to rotationally drive the tool accessory to perform a drilling operation.
A rotary hammer is configured to linearly drive a tool accessory coupled to a tool holder along a driving axis to perform a hammering operation. The rotary hammer is also configured to rotationally drive the tool accessory around the driving axis to perform a drilling operation. In typical known rotary hammers, a motion-converting mechanism for converting rotation of an intermediate shaft into linear motion is employed to perform the hammering operation, and a rotation-transmitting mechanism for transmitting rotation to the tool holder via the intermediate shaft is employed to perform the drilling operation.
In one aspect of the present teachings, a power tool, such as a rotary hammer or hammer drill, includes a final output shaft configured to removably hold a tool accessory and to be rotatable around a driving axis. A motor has a motor shaft extends in a direction intersecting the driving axis. A first intermediate shaft extends in parallel to the driving axis and a first driving mechanism is configured to convert rotation of the first intermediate shaft into linear reciprocating motion to hammer the tool accessory along the driving axis. A second intermediate shaft extends in parallel to the driving axis and a second driving mechanism is configured to transmit rotation of the second intermediate shaft to the final output shaft to rotationally drive the tool accessory around the driving axis. The motor shaft is configured to rotate a first one of the first intermediate shaft and the second intermediate shaft via a pair of bevel gears, and the first one of the first intermediate shaft and the second intermediate shaft is configured to rotate a second one of the first intermediate shaft and the second intermediate shaft via a pair of gears.
In such a design, because the power transmission path for the hammering operation can be placed in parallel to the power transmission path for the drilling operation, a more compact power tool in the front-rear direction can be achieved, thereby enabling the power tool to be conveniently and effectively utilized in a wider range of processing operations.
Additional objects, aspects, embodiments and advantages of the present teachings will be readily understandable to a person of ordinary skill in the art upon reading the following detailed description of embodiments of the present teachings in view of the appended drawings and claims.
An embodiment is now described with reference to the drawings. In this embodiment, a rotary hammer 101 is described as an example of a power tool having a hammering mechanism. The rotary hammer 101 is a hand-held power tool that may be used for processing operations such as chipping and drilling. The rotary hammer 101 is capable of performing the operation (hereinafter referred to as a hammering operation) of linearly driving a tool accessory 91 along a specified driving axis A1. The rotary hammer 101 is also capable of performing the operation (hereinafter referred to as a drilling operation) of rotationally driving the tool accessory 91 around the driving axis A1.
First, the general structure of the rotary hammer 101 is described with reference to
The body housing 10 is a hollow body, which may also be referred to as a tool body or an outer shell housing. The body housing 10 houses a spindle 31, a driving mechanism 5 and a motor 2. The spindle 31 is an elongate circular cylindrical member. An axial end portion of the spindle 31 includes a tool holder 32. The tool holder 32 is configured to removably hold the tool accessory 91. A longitudinal axis of the spindle 31 defines a driving axis A1 of the tool accessory 91. In this embodiment, the body housing 10 as a whole is generally L-shaped in a side view. The body housing 10 includes a driving-mechanism-housing part 11 that houses the spindle 31 and the driving mechanism 5, and a motor-housing part 12 that houses the motor 2. The driving-mechanism-housing part 11 extends along the driving axis A1. The tool holder 32 is disposed within one end portion of the driving-mechanism-housing part 11 in an extension direction of the driving axis A1 (hereinafter simply referred to as a driving-axis direction). The motor-housing part 12 protrudes obliquely from the other end portion of the driving-mechanism-housing part 11 in the driving-axis direction, in a direction away from the driving axis A1. The motor 2 is disposed within the motor-housing part 12 such that a rotation axis A2 of a motor shaft 25 extends in a direction intersecting the driving axis A1 (specifically, obliquely to the driving axis A1).
In the following description, for convenience sake, the extension direction of the driving axis A1 is defined as a front-rear direction of the rotary hammer 101. In the front-rear direction, the side of one end portion of the rotary hammer 101, within which the tool holder 32 is disposed, is defined as the front of the rotary hammer 101 and the opposite side is defined as the rear of the rotary hammer 101. A direction that is orthogonal to the driving axis A1 and that generally (substantially) corresponds to the extension direction of the rotation axis A2 of the motor shaft 25 is defined as an up-down direction of the rotary hammer 101. In the up-down direction, the direction which the motor-housing part 12 protrudes away from the driving-mechanism-housing part 11 is defined as a downward direction, and the opposite direction is defined as an upward direction. Further, a direction that is orthogonal to both the front-rear direction and the up-down direction is defined as a left-right direction.
The handle 15 as a whole is generally C-shaped in a side view. Both end portions of the handle 15 are connected to the body housing 10 to form a loop-shaped handle portion overall. The handle 15 includes an elongate cylindrical grip part 16 and a rectangular box-like controller-housing part 17. The grip part 16 is a portion configured to be held by a user. The grip part 16 is spaced apart rearward from the body housing 10 and extends generally in the up-down direction, intersecting the driving axis A1. A trigger 161 is provided in (at) a front upper end portion of the grip part 16. The trigger 161 is configured to be depressed by a user. A switch 162 is disposed within the grip part 16. The switch 162 is turned ON in response to a manual depressing of the trigger 161. The controller-housing part 17 houses a controller 171 for controlling driving of the motor 2. A battery-mounting part 173 is provided in a lower end portion of the controller-housing part 17. A rechargeable battery (battery pack) 93 may be removably mounted thereto as a power source of the motor 2, the controller 171, etc.
In this embodiment, the handle 15 is connected to the body housing 10 so as to be elastically movable relative to the body housing 10. Specifically, a lower end portion of the handle 15 is disposed within a lower end portion of the motor-housing part 12 and supported to be pivotable around a pivot axis extending in the left-right direction. Further, an upper end portion of the handle 15 is connected to a rear end portion of the driving-mechanism-housing part 11 via a biasing spring so as to be movable in the front-rear direction relative to the rear end portion.
In the rotary hammer 101, when the trigger 161 is depressed and the switch 162 is turned ON, the motor 2 is energized by the controller 171, so that the hammering operation and/or the drilling operation is performed.
The detailed structure of the rotary hammer 101 is now described.
First, the structure of the body housing 10 (the motor-housing part 12 and the driving-mechanism-housing part 11) and its internal structures are described.
As shown in
As shown in
The spindle 31 is a final output shaft of the rotary hammer 101. The spindle 31 is supported by bearings 316 and 317 so as to be rotatable around the driving axis A1 relative to the body housing 10. A front half of the spindle 31 forms the tool holder 32, to which the tool accessory 91 is removably attachable. The tool accessory 91 is inserted into the tool holder 32, such that a longitudinal axis of the tool accessory 91 coincides with the driving axis A1. The tool accessory 91 is movable relative to the tool holder 32 in a direction of the longitudinal axis of the tool holder 32, while its rotation relative to the tool holder 32 is restricted (i.e. the tool accessory 91 rotates together with the tool holder 32). A rear half of the spindle 31 forms a cylinder 33 that slidably holds a piston 65, which will be described below. In this embodiment, the spindle 31 is a single (integral) member including the tool holder 32 and the cylinder 33. The spindle 31, however, may be formed by connecting a plurality of members.
The driving mechanism 5 includes a striking mechanism 6 configured to perform the hammering operation, and a rotation-transmitting mechanism 7 (see
The arrangement of the first intermediate shaft 41 and the second intermediate shaft 42 is now described.
As shown in
As shown in
As shown in
In this embodiment, the rotation axis A3 of the first intermediate shaft 41 and the rotation axis A2 of the motor shaft 25 both extend in (coincide with) the reference plane P and intersect each other. More specifically, the rotation axis A2 and the rotation axis A3 intersect with each other so as to form an acute angle therebetween. Therefore, in this embodiment, straight bevel gears, which are simple in structure and relatively cheap, are employed as the driving bevel gear 255 and the driven bevel gear 414. The driving bevel gear 255 and the driven bevel gear 414, however, may be a pair of a different kind of gears with intersecting axes (e.g. a pair of spiral bevel gears). The driving bevel gear 255 and the driven bevel gear 414 form a speed-reducing (torque-increasing) gear mechanism.
Further, as shown in
The gear member 423 has a circular cylindrical shape. The gear member 423 is disposed on the outer peripheral side of the second intermediate shaft 42 (specifically, on the outer peripheral side of a drive-side member 74). A spline part 425 is provided on an outer periphery of a cylindrical front end portion of the gear member 423. The spline part 425 includes a plurality of splines (external teeth) extending in a direction of the rotation axis A4 (i.e. front-rear direction). Rotation of the gear member 423 is transmitted to the second intermediate shaft 42 via a second transmitting member 72 and a torque limiter 73, which will be described in detail below.
The detailed structures of the striking mechanism 6 and the rotation-transmitting mechanism 7 are now described in this order.
The striking mechanism 6 is a mechanism for performing the hammering operation, and is configured to convert rotation of the first intermediate shaft 41 into linear reciprocating motion and linearly (reciprocally) drive the tool accessory 91 along the driving axis A1. In this embodiment, as shown in
The motion-converting member 61 is disposed on (around) the first intermediate shaft 41. The motion-converting member 61 is configured to convert rotation of the first intermediate shaft 41 into linear reciprocating motion and transmit it to the piston 65. More specifically, the motion-converting member 61 includes a rotary body 611 and an oscillating member 616.
The rotary body 611 is supported by a bearing 614 so as to be rotatable around the rotation axis A3 relative to the body housing 10. In this embodiment, a circular cylindrical intervening member 63 is disposed between the rotary body 611 and the first intermediate shaft 41. The intervening member 63 is configured to be immovable in the front-rear direction relative to the first intermediate shaft 41, while being selectively rotatable relative to the first intermediate shaft 41 together with the rotary body 611. A front end portion of the intervening member 63 protrudes forward from a front end of the rotary body 611. The oscillating member 616 is mounted on (around) the rotary body 611, and configured to oscillate (pivot or rock back-and-forth) in an extension direction of the rotation axis A3 (i.e. front-rear direction) while the rotary body 611 is rotating. To achieve this oscillating (linear reciprocating) motion, a plurality of rolling elements (e.g., balls) is disposed on (in) an elliptical track defined by an outer surface of the roller body 611 (which acts as an inner ring of a roller bearing) and an inner surface of the oscillating member 616 (which acts as an outer ring of the roller bearing), whereby rotation of the roller body 611 (inner ring) causes the oscillating member 616 (outer ring) to reciprocally pivot within a predetermined angular range about a horizontal line that intersects and is perpendicular to the rotational axis of the first intermediate shaft 41. The oscillating member 616 has an arm part 617 extending upward away from the rotary body 611, which arm 617 moves back and forth in a direction parallel to the rotational axis of the first intermediate shaft 41 while the rotary body 611 is rotating, owing to the connection of the arm 617 to the piston 65. The oscillating member 616 may alternatively be called a rocking member or a pivoting member and refers to a structure having a function of oscillating or pivoting within a predetermined angular range about a line intersecting the rotational axis of the first intermediate shaft 41. It is noted that the motion-converting member/mechanism (also known as a rotation-to-linear reciprocating motion converting mechanism) 61 may be implemented as a swash bearing in the present embodiment, or in alternate embodiments, with a barrel cam follower, a wobble plate assembly, etc.
The piston 65 is a bottomed circular cylindrical member. The piston 65 is disposed within the cylinder 33 of the spindle 31 so as to be slidable along the driving axis A1. The piston 65 is connected to the arm part 617 of the oscillating member 616 via a connecting pin and reciprocally moves in the front-rear direction while the oscillating member 616 is oscillating (pivoting or rocking back-and-forth in the front-rear direction).
The striker 67 is a striking element for applying a striking force to the tool accessory 91. The striker 67 is disposed within the piston 65 so as to be slidable along the driving axis A1. An internal space of the piston 65 behind the striker 67 is defined as an air chamber that serves as an air spring. The impact bolt 68 is an intermediate element for transmitting kinetic energy of the striker 67 to the tool accessory 91. The impact bolt 68 is disposed within the tool holder 32 in front of the striker 67 so as to be movable along the driving axis A1.
When the piston 65 is reciprocally moved in the front-rear direction along with (in response to) oscillating movement of the oscillating member 616, the air pressure within the air chamber fluctuates and the striker 67 slides in the front-rear direction within the piston 65 by the action of the air spring. More specifically, when the piston 65 is moved forward, the air within the air chamber is compressed and its internal pressure increases. Thus, the striker 67 is pushed forward at high speed by the action of the air spring and strikes the impact bolt 68. The impact bolt 68 transmits the kinetic energy of the striker 67 to the tool accessory 91. Thus, the tool accessory 91 is linearly driven along the driving axis A1. On the other hand, when the piston 65 is moved rearward, the air within the air chamber expands and its internal pressure decreases, so that the striker 67 moves rearward. The tool accessory 91 moves rearward together with the impact bolt 68 by being pressed against a workpiece. In this manner, the striking mechanism 6 repetitively performs the hammering operation.
In this embodiment, rotation of the first intermediate shaft 41 is transmitted to the motion-converting member 61 (specifically, the rotary body 611) via a first transmitting member 64 and the intervening member 63.
The first transmitting member 64 is disposed on (around) the first intermediate shaft 41 in a co-axial manner. The first transmitting member 64 is configured to be rotatable together with the first intermediate shaft 41. The first transmitting member 64 is also configured to be movable in the direction of the rotation axis A3 (i.e. front-rear direction) relative to the first intermediate shaft 41 and the intervening member 63. More specifically, a first spline part 641, which is selectively engageable with the intervening member 63, and a second spline part 642, which is always engaged with the spline part 416 of the first intermediate shaft 41, are provided on an inner periphery of the first transmitting member 64.
The first spline part 641 is provided on an inner periphery of a rear end portion of the first transmitting member 64. The first spline part 641 includes a plurality of splines (internal teeth) extending in the direction of the rotation axis A3 (i.e. front-rear direction). Correspondingly, a spline part 631 is provided on an outer periphery of the front end portion of the intervening member 63. The spline part 631 includes a plurality of splines (external teeth) configured to be selectively engaged (meshed) with the first spline part 641.
The second spline part 642 is provided on an inner periphery of a front half of the first transmitting member 64. The second spline part 642 includes a plurality of splines (internal teeth) extending in the direction of the rotation axis A3 (i.e. front-rear direction). Correspondingly, a front end portion (a portion adjacent to the rear of the front bearing 411) of the first intermediate shaft 41 is configured as a large-diameter part. The spline part 416 is provided on an outer periphery of the large-diameter part. The spline part 416 includes a plurality of splines (external teeth) that are always engaged (meshed) with the second spline part 642.
With such a structure, when the first spline part 641 is placed in a position (hereinafter referred to as an engagement position) where it is engaged with the spline part 631 of the intervening member 63 in the front-rear direction, as shown by solid lines in
As described above, in this embodiment, the first transmitting member 64 and the intervening member 63 function as a first clutch mechanism 62 that transmits power for the hammering operation or interrupts this power transmission. In this embodiment, the first transmitting member 64 is connected to a mode-changing mechanism 80 (see
The rotation-transmitting mechanism 7 is a mechanism for performing the drilling operation. The rotation-transmitting mechanism 7 is configured to transmit rotation of the second intermediate shaft 42 to the spindle 31 and thereby rotationally drive the tool accessory 91 around the driving axis A1. As shown in
As described above, in this embodiment, rotation of the driven gear 424, which is rotated by the first intermediate shaft 41, is transmitted to the second intermediate shaft 42 via the second transmitting member 72 and the torque limiter 73. The torque limiter 73 and the second transmitting member 72 are now described in this order.
As shown in
The drive-side member 74 is a circular cylindrical member. The drive-side member 74 is rotatably supported by a rear half of the second intermediate shaft 42. The driven gear 424 is rotatably supported by a rear end portion of the drive-side member 74. Therefore, the drive-side member 74 is rotatable around the rotation axis A4 relative to the second intermediate shaft 42 and the driven gear 424.
The drive-side member 74 includes cam recesses 742 (see
The driven-side member 75 is a circular cylindrical member. The driven-side member 75 is disposed around the second intermediate shaft 42 in front of the drive-side member 74. On an inner periphery of the driven-side member 75, a plurality of grooves are arranged in (around) a circumferential direction. The grooves each extend in the rotation axis A4 direction (i.e. front-rear direction). Further, on an outer periphery of the second intermediate shaft 42, a plurality of grooves are arranged in (around) a circumferential direction. The grooves each extend in the direction of the rotation axis A4 (i.e. front-rear direction). The balls 76 are respectively accommodated within tracks defined by the corresponding grooves, so as to be rollable along the respective tracks that each extend in the front-rear direction, i.e. in parallel to the driving axis A1. Thus, the driven-side member 75 is engaged with the second intermediate shaft 42 via the balls 76 in a radial direction and the circumferential direction, and is rotatable together with the second intermediate shaft 42. Further, the driven-side member 75 is movable in the front-rear direction relative to the second intermediate shaft 42 within a range in which the balls 76 roll within the tracks.
The driven-side member 75 has cam projections 752 (see
Although not shown in detail, when a load exceeding the threshold is applied to the second intermediate shaft 42 via the tool holder 32 (the spindle 31) due to jamming or binding of the tool accessory 91 or other causes, the cam projections 752 disengage from the cam recesses 742. More specifically, owing to the interaction of the cam faces (inclined surface) of the cam projections 752 and the cam recesses 742, the cam projections 752 disengage from the cam recesses 742, against the biasing force of the biasing spring 77, and abut on a front end surface of the drive-side member 74. Thus, the driven-side member 75 moves in a direction away from the drive-side member 74 (i.e. forward). At this time, the driven-side member 75 can smoothly move forward, while being guided by the balls 76 that roll between (in the tracks defined by) the driven-side member 75 and the second intermediate shaft 42. As a result, torque transmission from the drive-side member 74 to the driven-side member 75 is interrupted and thus rotation of the second intermediate shaft 42 is interrupted.
As shown in
More specifically, the second transmitting member 72 is a generally circular cylindrical member. The second transmitting member 72 is disposed around the drive-side member 74. A first spline part 721 and a second spline part 722 are provided on an inner periphery of the second transmitting member 72. The first spline part 721 is provided on a front half of the second transmitting member 72. The first spline part 721 includes a plurality of splines (internal teeth) that are always engaged (meshed) with the spline part 743 of the drive-side member 74. The second spline part 722 is provided on a rear end portion of the second transmitting member 72. The second spline part 722 includes a plurality of splines (internal teeth) configured to be engaged (meshed) with the spline part 425 of the gear member 423.
With such a structure, when the second spline part 722 is placed in a position (hereinafter referred to as an engagement position) where it is engaged with the spline part 425 of the gear member 423 in the front-rear direction, as shown by solid lines in
As described above, in this embodiment, the second transmitting member 72 and the gear member 423 function as a second clutch mechanism 71 that transmits power for the drilling operation or interrupts this power transmission. In this embodiment, like the first transmitting member 64, the second transmitting member 72 is connected to the mode-changing mechanism 80 (see
The mode-changing dial 800 and the mode-changing mechanism 80 are now described.
As shown in
As shown in
The operation part 801 is held by the body housing 10 so as to be rotatable around a pivot axis R (see
The mode-changing mechanism 80 includes a first switching member 81, a second switching member 82, a first spring 83 and a second spring 84.
The first switching member 81 has a pair of support holes (not shown). The first switching member 81 is supported to be movable in the front-rear direction by a support shaft 88, which is inserted through the support holes of the first switching member 81. The support shaft 88 is fixed to the body housing 10 (specifically, to a support wall 113 fixed inside the driving-mechanism-housing part 11). The support shaft 88 extends in the front-rear direction, in parallel to the first and second intermediate shafts 41 and 42. A retaining ring 881 is fixed to a central portion of the support shaft 88 in an axial direction of the support shaft 88. The first switching member 81 is supported in front of the retaining ring 881. The second switching member 82 has a pair of support holes (not shown). The second switching member 82 is supported to be movable in the front-rear direction by the support shaft 88, which is inserted through the support holes of the second switching member 82. The second switching member 82 is disposed behind the retaining ring 881.
The first and second switching members 81 and 82 are respectively engaged with the first and second transmitting members 64 and 72. More specifically, annular grooves 645 and 725 are formed on (in) the outer peripheries of the first and second transmitting members 64 and 72, respectively. The first switching member 81 is engaged with the first transmitting member 64 via a plate-like first engagement part 813 (see
The first spring 83 is a compression coil spring. The first spring 83 is disposed in a compressed state between the driving-mechanism-housing part 11 and the first switching member 81, and always biases the first switching member 81 rearward. Thus, the first transmitting member 64 engaged with the first switching member 81 is also always biased rearward toward the engagement position. The second spring 84 is a compression coil spring. The second spring 84 is disposed in a compressed state between the retaining ring 881 fixed to the support shaft 88 and the second switching member 82, and always biases the second switching member 82 rearward. Thus, the second transmitting member 72 engaged with the second switching member 82 is also always biased rearward toward the engagement position. A rearmost position of the first switching member 81 is a position where the first switching member 81 abuts on the retaining ring 881. A rearmost position of the second switching member 82 is a position where the second switching member 82 abuts on a front surface of the support wall 113.
When the mode-changing dial 800 is set (turned) to the rotational position that corresponds to the hammer-drill mode (hereinafter referred to as the hammer-drill position) shown in
When the motor 2 is energized, power (rotational motion) is transmitted from the motor shaft 25 to the first intermediate shaft 41 via the driving bevel gear 255 and the driven bevel gear 414. Power is then transmitted from the first intermediate shaft 41 to the striking mechanism 6 via the first clutch mechanism 62, so that the hammering operation is performed. At the same time, power (rotational motion) is transmitted from the first intermediate shaft 41 to the second intermediate shaft 42 via the driving gear 415 and the driven gear 424, and further via the second clutch mechanism 71 and the torque limiter 73. This power is then transmitted from the second intermediate shaft 42 to the spindle 31 via the rotation-transmitting mechanism 7, so that the drilling operation is also performed.
When the mode-changing dial 800 is manually turned from the hammer-drill position shown in
Furthermore, at the same time, the first pin 803 moves in the clockwise direction (when viewed from the left) without interfering with (contacting) the first and second switching members 81 and 82, and is moved to a position spaced apart (separated) from the first and second switching members 81 and 82. Therefore, during this time, the first switching member 81 and the first transmitting member 64 do not move, and thus the first clutch mechanism 62 remains in the power-transmitting state.
In this state, even when the motor 2 is energized, power (rotational motion) is not transmitted from the motor shaft 25 to the second intermediate shaft 42, so that a drilling operation is not performed. On the other hand, power (rotational motion) is transmitted from the motor shaft 25 to the striking mechanism 6 via the first intermediate shaft 41, so that only the hammering operation is performed.
When the mode-changing dial 800 is manually turned from the hammer-drill position shown in
At the same time, the second pin 805 moves in the counterclockwise direction (when viewed from the left) around the pivot axis R of the operation part 801 without interfering with (contacting) the first and second switching members 81 and 82 and is placed in (at) a position adjacent to the second switching member 82. Therefore, during this time, the second switching member 82 and the second transmitting member 72 do not move, and thus the second clutch mechanism 71 remains in the power-transmitting state.
In this state, even when the motor 2 is energized, power (rotational motion) is not transmitted from the first intermediate shaft 41 to the motion-converting member 61, so that a hammering operation is not performed. On the other hand, power (rotational motion) is transmitted from the motor shaft 25 to the rotation-transmitting mechanism 7 via the second intermediate shaft 42, so that only the drilling operation is performed.
As described above, in the rotary hammer 101 of this embodiment, the spindle 31, the first intermediate shaft 41 for the striking mechanism 6 that performs the hammering operation, and the second intermediate shaft 42 for the rotation-transmitting mechanism 7 that performs the drilling operation extend in parallel to each other. The motor shaft 25 extends in the direction that intersects the spindle 31. Rotation of the motor shaft 25 is first transmitted to the first intermediate shaft 41 via the driving bevel gear 255 and the driven bevel gear 414, and is then further transmitted to the second intermediate shaft 42 via the driving gear 415 and the driven gear 424. Thus, the spindle 31 is not located on (in) a power transmission path between the first intermediate shaft 41 and the second intermediate shaft 42. Therefore, unlike an embodiment in which rotation is transmitted from the second intermediate shaft 42 to the first intermediate shaft 41 via the spindle 31, a reduction and an increase of the rotation speed is not required. As a result, efficient power transmission can be realized.
Further, the hammering operation tends to cause a larger load than the drilling operation. Therefore, this embodiment employs a structure in which torque is directly transmitted from the motor shaft 25 to the first intermediate shaft 41, which is subjected to a larger load than the second intermediate shaft 42.
On the first intermediate shaft 41, the driven bevel gear 414 is disposed adjacent to (in abutment with) the front of the bearing 412, and the driving gear 415 is disposed between the driven bevel gear 414 and the motion-converting member 61. In other words, the driven bevel gear 414 and the driving gear 415 are disposed in the vicinity of the bearing 412 that supports the first intermediate shaft 41. Owing to this arrangement, a section (segment) on which the driven bevel gear 414 and the driving gear 415 are disposed can be reduced or minimized in the front-rear direction. Further, the section of the first intermediate shaft 41 in the vicinity of the bearing is less prone to deflect (bend). Therefore, owing to the concentrated (compact) arrangement of the above-described various gears on this section (segment), engagement between the driving bevel gear 255 and the driven bevel gear 414 and engagement between the driving gear 415 and the driven gear 424 can be accurately maintained.
Further, the first intermediate shaft 41 is required to be a certain minimum length because the motion-converting member 61 is mounted on (around) the first intermediate shaft 41. On the other hand, the driving gear 78 that is mounted onto the second intermediate shaft 42 is not required to be so long. In this embodiment, as described above, the position of the driven gear 424 on the second intermediate shaft 42 is determined by the position of the driving gear 415, which is disposed in the vicinity of the rear bearing 412. As a result, there is abundant space in front of the driven gear 424 on the second intermediate shaft 42. Therefore, the torque limiter 73 is rationally arranged, utilized this space. The torque transmitted by the second intermediate shaft 42 is less than the torque on the spindle 31, which serves as the final output shaft. Therefore, the torque limiter 73 can be smaller and lighter in the present embodiment than in an embodiment in which a torque limiter is mounted on the spindle 31.
Further, during operation of the torque limiter 73 of this embodiment, the rolling balls 76 can guide movement of the driven-side member 75 in the direction of the rotation axis A4. This structure can reduce friction between the driven-side member 75 and the second intermediate shaft 42, and thus stabilize the operating (output) torque.
In this embodiment, the driving axis A1, the rotation axis A2 of the motor shaft 25 and the rotation axis A3 of the first intermediate shaft 41 all extend in (coincide with) the same reference plane P. Further, the rotation axis A4 of the second intermediate shaft 42 is located on the left side of the reference plane P. Therefore, the center of gravity of the rotary hammer 101 may be disposed (offset) to the left of the reference plane P. However, because there are more right-handed users than left-handed users, it is believed that right-handed users can easily cope with the deviation (offset) of the center of gravity by holding an auxiliary handle, which is mounted on the barrel part 111, with the left hand. Therefore, it is appropriate that the rotation axis A4 of the second intermediate shaft 42 is located on the left side of the reference plane P, rather than on the right side.
Further, in this embodiment, the first clutch mechanism 62 and the second clutch mechanism 71 are respectively provided on the first intermediate shaft 41 and the second intermediate shaft 42. Therefore, power for the hammering operation and power for the drilling operation can be separately (independently) interrupted as needed. Further, both the first clutch mechanism 62 and the second clutch mechanism 71 can be switched between the power-transmitting state and the power-interrupting state, in response to manual operation of the same operation member (i.e. the mode-changing dial 800). Therefore, a user can cause the first clutch mechanism 62 and the second clutch mechanism 71 to operate, by simply operating (turning) the mode-changing dial 800 to change the action mode, depending on the desired processing operation. Particularly, in this embodiment, a free space below the second intermediate shaft 42 is utilized to rationally arrange the mode-changing dial 800 and the mode-changing mechanism 80.
Correspondences between the features of the above-described embodiment and the features of the disclosure are as follows. The features of the above-described embodiment are merely exemplary and do not limit the features of the present invention. The rotary hammer 101 is an example of the “power tool”. The spindle 31 is an example of the “final output shaft”. The driving axis A1 is an example of the “driving axis”. The motor 2 and the motor shaft 25 are examples of the “motor” and the “motor shaft”, respectively. The first intermediate shaft 41 is an example of the “first intermediate shaft”. The striking mechanism 6 is an example of the “first driving mechanism”. The second intermediate shaft 42 is an example of the “second intermediate shaft”. The rotation-transmitting mechanism 7 is an example of the “second driving mechanism”. The driving bevel gear 255 and the driven bevel gear 414 are an example of the “pair of bevel gears”. The driving gear 415 and the driven gear 424 are an example of the “pair of gears”.
The motion-converting member 61 is an example of the “motion-converting member”. The bearing 412 is an example of the “bearing”. The driven bevel gear 414 is an example of the “one of the bevel gears”. The torque limiter 43 is an example of the “torque limiter”. The first clutch mechanism 62 and the second clutch mechanism 71 are examples of the “first clutch mechanism” and the “second clutch mechanism”, respectively. The mode-changing dial 800 (the operation part 801) is an example of the “operation member”. The drive-side member 74, the driven-side member 75 and the ball 76 are examples of the “drive side cam”, the “driven side cam” and the “ball”, respectively. The biasing spring 77 is an example of the “biasing member”. The mode-changing mechanism 80, the first switching member 81 and the second switching member 82 are examples of the “switching mechanism”, the “first switching member” and the “second switching member”, respectively. The first pin 803 and the second pin 805 are examples of the “first abutment part” and the “second abutment part”, respectively. The support shaft 88 is an example of the “support member”.
The above-described embodiment is merely an exemplary embodiment of the disclosure, and a power tool according to the present disclosure is not limited to the rotary hammer 101 of the above-described embodiment. For example, the following modifications may be made. One or more of these modifications may be adopted in combination with the rotary hammer 101 of the above-described embodiment or the claimed features.
The rotary hammer 101 may be configured to be operated using power supplied from an external AC power source, instead from a rechargeable battery. In such an embodiment, a power cable (power cord) that is connectable to the external AC power source may be provided, in place of the battery-mounting part 173. Further, the motor 2 may be an AC motor, instead of a DC motor. The motor 2 may be a motor with a brush, instead of a brushless motor.
The structures (such as shapes, components and materials) of the body housing 10 and the handle 15 may be appropriately changed. For example, the motor-housing part 12 may protrude downward in a direction that is orthogonal to the driving axis A1 from the rear end portion of the driving-mechanism-housing part 11. In such an embodiment, the motor 2 may be arranged such that the rotation axis A2 of the motor shaft 25 extends orthogonally to the rotation axis A3 of the first intermediate shaft 41.
Further, the body housing 10 may have a vibration-isolating structure that is different from that of the above-described embodiment. For example, both end portions of the handle 15 may be connected to the body housing 10 so that both ends are elastically movable relative to the body housing 10. Alternatively, the body housing 10 may include an inner housing that houses the driving mechanism 5, and an outer housing that includes a grip part configured to be held by a user and is elastically connected to the inner housing so as to be movable relative to the inner housing. Further, the spindle 31 and the striking mechanism 6 may be supported by a support body within the body housing 10 such that the spindle 31, the striking mechanism 6 and the support body are integrally movable in the front-rear direction relative to the body housing 10. Such a vibration-isolating structure is disclosed, for example, in US Patent Publication No. 2017/0106517, which is hereby incorporated by reference.
The positions of the first intermediate shaft 41 (the rotation axis A3) and the second intermediate shaft 42 (the rotation axis A4) relative to the motor shaft 25 (the rotation axis A2), and the positions of the first intermediate shaft 41 (the rotation axis A3) and the second intermediate shaft 42 (the rotation axis A4) relative to the spindle 31 (the driving axis A1) are not limited to those of the above-described embodiment.
For example, rotation of the motor shaft 25 may be first transmitted to the second intermediate shaft 42 and then transmitted from the second intermediate shaft 42 to the first intermediate shaft 41. In such an embodiment, it may be preferable that a driven bevel gear is disposed adjacent to the front of the bearing 422 of the second intermediate shaft 42 to mesh with the driving bevel gear 255, and a driving gear is further disposed adjacent to the front of the driven bevel gear. Further, a driven gear may be disposed adjacent to the front of the bearing 412 of the first intermediate shaft 41 to mesh with the driving gear of the second intermediate shaft 42.
The rotation axis A2 of the motor shaft 25 and the rotation axis A3 of the first intermediate shaft 41 (or the rotation axis A4 of the second intermediate shaft 42) need not extend in (coincide with) the same plane. In such a modified embodiment, rotation of the motor shaft 25 may be transmitted to the first intermediate shaft 41 (or to the second intermediate shaft 42), for example, via a pair of hypoid gears. Further, the driving axis A1 need not extend in the same plane as the rotation axis A2 of the motor shaft 25 and/or the rotation axis A3 of the first intermediate shaft 41 (or the rotation axis A4 of the second intermediate shaft 42).
The structures and positions of the first and second clutch mechanisms 62, 71, the torque limiter 73 and the mode-changing mechanism 80 may be appropriately changed.
For example, the intervening member 63 may be omitted, and the first transmitting member 64 of the first clutch mechanism 62 may be movable between a position where it is engaged with the motion-converting member 61 (specifically, with the rotary body 611) and a position where it is spaced apart from the motion-converting member 61. In other words, the first transmitting member 64 may be configured to directly transmit rotation of the first intermediate shaft 41 to the motion-converting member 61 (specifically, to the rotary body 611). Further, the second clutch mechanism 71 may be configured to transmit power and to interrupt the power transmission not between the driven gear 424 and the second intermediate shaft 42, but between the second intermediate shaft 42 and the driving gear 78.
The rotary hammer 101 may be configured to perform only the hammer-drill mode and the hammer mode among the three action modes, i.e. the hammer-drill mode, the hammer mode and the drill mode (i.e. the drill mode may be omitted). In such an embodiment, only the second clutch mechanism 71 may be provided on the second intermediate shaft 42 and the first clutch mechanism 62 may be omitted. Furthermore, the first switching member 81 and the first spring 83 of the mode-changing mechanism 80 may also be omitted.
The driven-side member 75 of the torque limiter 73 and the second intermediate shaft 42 may be spline-engaged with each other, instead of being engaged via the balls 76. Not the driven-side member 75 but the drive-side member 74 may be movable on the second intermediate shaft 42. Further, the torque limiter 73 may be omitted, or may be provided on the spindle 31.
In the mode-changing mechanism 80, the shapes and positions of the first and second switching members 81 and 82, the first and second springs 83 and 84, as well as their manner of movement along with the mode-changing dial 800 may be appropriately changed. For example, the first switching member 81 for switching the first clutch mechanism 62 and the second switching member 82 for switching the second clutch mechanism 71 may be configured to be moved by separate (discrete) operation members, respectively. Further, the operation member that is configured to operate the mode-changing mechanism 80 is not limited to a rotary dial, and may be, for example, a slide lever. The first and second springs 83 and 84 may be other kinds of springs (such as a tensile coil spring or a torsion spring). The first and second switching members 81 and 82 need not necessarily be biased.
Further, in view of the nature of the present disclosure and the above-described embodiment, the following aspects can be provided. Any one of the following aspects can be employed in combination with any one of the rotary hammer 101 of the above-described embodiment, its modifications and the claimed features.
(Aspect 1)
The rotation axis of the motor shaft and a rotation axis of the first intermediate shaft are (extend) in the same plane.
(Aspect 2)
The rotation axis of the second intermediate shaft is located on the left side of the driving axis.
(Aspect 3)
The first driving mechanism includes:
an oscillating member disposed on the first intermediate shaft and configured to oscillate in accordance with (in response to) rotation of the first intermediate shaft,
a piston configured to reciprocate along the driving axis in accordance with oscillating movement of the oscillating member, and
a striking element configured to linearly move owing to action of an air spring generated by reciprocating movement of the piston and thereby linearly dive the tool accessory.
The motion-converting member 61 (the oscillating member 616), the piston 65 and the striker 67 are examples of the “oscillating member”, the “piston” and the “striking element”, respectively, in this aspect.
(Aspect 4)
The second driving mechanism is a speed-reducing gear mechanism that includes:
a first rotation-transmitting gear disposed on the second intermediate shaft and configured to rotate together with the second intermediate shaft, and
a second rotation-transmitting gear provided on an outer periphery of the final output shaft and meshing with the first rotation-transmitting gear.
The driving gear 78 and the driven gear 79 are examples of the “first rotation-transmitting gear” and the “second rotation-transmitting gear”, respectively, in this aspect.
This application hereby incorporates by reference the entire disclosure of U.S. application Ser. No. 17/072,462, and the entire disclosure of U.S. application Ser. No. 17/072,484.
Representative, non-limiting examples of the present invention were described above in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Furthermore, each of the additional features and teachings disclosed above may be utilized separately or in conjunction with other features and teachings to provide improved power tools having a hammer mechanism.
Moreover, combinations of features and steps disclosed in the above detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Furthermore, various features of the above-described representative examples, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.
All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter.
101: rotary hammer, 2: motor, 5: driving mechanism, 6: striking mechanism, 7: rotation-transmitting mechanism, 10: body housing, 11: driving-mechanism-housing part, 12: motor-housing part, 15: handle, 16: grip part, 17: controller-housing part, 20: body, 25: motor shaft, 31: spindle, 32: tool holder, 33: cylinder, 41: first intermediate shaft, 42: second intermediate shaft, 61: motion-converting member, 62: first clutch mechanism, 63: intervening member, 64: first transmitting member, 65: piston, 67: striker, 68: impact bolt, 71: second clutch mechanism, 72: second transmitting member, 73: torque limiter, 74: drive-side member, 75: driven-side member, 76: ball, 77: biasing spring, 78: driving gear, 79: driven gear, 80: mode-changing mechanism, 81: first switching member, 82: second switching member, 83: first spring, 84: second spring, 88: support shaft, 91: tool accessory, 111: barrel part, 113: support wall, 161: trigger, 162: switch, 171: controller, 173: battery-mounting part, 251: bearing, 255: driving bevel gear, 316: bearing, 411: bearing, 412: bearing, 414: driven bevel gear, 415: driving gear, 416: spline part, 421: bearing, 422: bearing, 423: gear member, 424: driven gear, 425: spline part, 611: rotary body, 614: bearing, 616: oscillating member, 617: arm part, 631: spline part, 641: first spline part, 642: second spline part, 645: groove, 721: first spline part, 722: second spline part, 725: groove, 742: cam recess, 743: spline part, 752: cam projection, 800: mode-changing dial, 801: operation part, 803: first pin, 805: second pin, 813: first engagement part, 823: second engagement part, 881: retaining ring, A1: driving axis, A2: rotation axis, A3: rotation axis, A4: rotation axis, P: reference plane, R: pivot axis
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