The present invention relates to rotary tools and, more particularly, to a drive system for a rotary tool.
A rotary tool, such as an impact wrench, generally includes a housing supporting a motor, a drive mechanism driven by the motor, an output shaft having a first end adapted to engage a fastener and a second end adapted to engage the drive mechanism. In impact wrenches, the drive mechanism generally includes a hammer member, which periodically impacts the output shaft, rotating the output shaft about a central axis to hammer or drive fasteners into or remove fasteners from a work piece.
The present invention provides a rotary tool, such as an impact wrench. In one construction, the rotary tool includes a housing having a forward end and supporting a motor. The motor has a motor shaft extending axially through the housing and defining an axis. A frame is coupled to the motor shaft and is rotatable relative to the housing about the axis in response to rotation of the motor shaft. The frame defines an interior space. A piston is supported by the frame and is moveable axially in the interior space. An output shaft is supported in the forward end of the housing and is rotatable about the axis. The output shaft has a plurality of cams. The piston is engageable with the plurality of cams to intermittently deliver torque impulses to the output shaft.
In another construction, the output shaft includes a rearward surface and the plurality of cams extend axially from the rearward surface. The piston includes an axially extending portion and the output shaft defines an aperture. The axially extending portion is receiveable in the aperture.
In yet another construction, the frame defines an axially extending groove and the piston includes a plurality of radially extending arms. The plurality of radially extending arms are engageable in the axially extending groove to transfer rotational motion from the frame to the piston.
In still another construction, the rotary tool includes a housing having a forward end and supporting a motor. The motor has a motor shaft extending axially through the housing and defining an axis. A frame is coupled to the motor shaft and is rotatable relative to the housing about the axis in response to rotation of the motor shaft. The frame has a first end and a second end and defines an interior space between the first end and the second end. A piston is supported in the frame and is moveable axially in the interior space between a retracted position, in which the piston is adjacent the second end, and an extended position, in which the piston is spaced a distance from the second end. An output shaft is supported in the forward end of the housing and is rotatable about the axis. The piston is engageable with the output shaft to deliver torque impulses to the output shaft about the axis when the piston is in the extended position.
In another construction, the rotary tool includes a housing having a forward end and supporting a motor. The motor has a motor shaft extending axially through the housing and defining an axis. A frame is coupled to the motor shaft and is rotatable relative to the housing about the axis in response to rotation of the motor shaft. The frame defines an internal space. A piston is supported in the internal space for rotation with the frame about the axis. An output shaft is supported in the forward end of the housing and is rotatable about the axis. One of the output shaft and the piston has a protrusion. Another of the output shaft and the piston has a contoured recess. The protrusion is engageable in the recess to rotatably couple the output shaft and the piston. The protrusion cammingly engages the contoured recess to reciprocate the piston along the axis.
The present invention also provides a method of operating the rotary tool.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.
The present invention is further described with reference to the accompanying drawings, which show constructions of the present invention. However, it should be noted that the invention as disclosed in the accompanying drawings is illustrated by way of example only. The various elements and combinations of elements described below and illustrated in the drawings can be arranged and organized differently to result in constructions which are still within the spirit and scope of the present invention.
In the drawings, wherein like reference numerals indicate like parts:
As used herein and in the appended claims, the terms “upper”, “lower”, “first”, “second”, “third”, “forward”, and “rearward” are used herein for description only and are not intended to imply any particular orientation, order, or importance.
The handle 20 includes an air channel 32 having an inlet 34. In some constructions (not shown), the air channel 32 includes seals (e.g., O-rings, washers, etc.), filters (e.g., air strainers), and valves (e.g., spring-operated valves) for controlling air quality into and airflow through the rotary tool 10. Additionally, in some constructions (not shown), the air channel 32 includes a throttle valve (not shown) that is operably connected to the trigger 26 for controlling the flow of air through the air channel 32, the operating speed of the rotary tool 10, and/or the torque generated by the rotary tool 10. Also, in rotary tools 10 having forward and reverse modes, a reverse valve (not shown) may be positioned along the air channel 32 to direct air flow through the motor 22 in either of two directions (i.e., forward and reverse).
The rearward portion 18 of the housing 12 defines a cavity 36 surrounding the motor 22. The motor shaft 24 extends through the cavity 36 along the central axis A and is supported by bearings 38, 40 for rotation relative to the housing 12. Pressurized air from the air channel 32 enters the rearward end of the cavity 36 and travels across the motor 22, causing the motor 22 to rotate about the central axis A in a conventional manner. In some constructions, the cavity 36 is sealed (e.g., the cavity includes O-rings, washers, valves, etc.) to prevent unintended air exchange with the atmosphere. One having ordinary skill in the art will appreciate that while one type of air motor has been described herein and is shown in the figures, other types of air motors (not shown) could also or alternately be used. In other constructions (not shown), electric motors (not shown) could also or alternately be used.
Fasteners (not shown) extend through the forward portion 16 of the housing 12 and into bores 42 located in the rearward portion 18 of the housing 12, coupling the forward and rearward portions 16, 18 of the housing 12. A seal (e.g., an O-ring, a washer, etc.) 46 is arranged between the forward and rearward portions 16, 18 to prevent airflow into or out of the housing 12 between the forward and rearward portions 16, 18.
With reference to
With reference to
As shown in
The forward surface 48 defines a forward opening 71 communicating with the interior space 67. A cover 72 is coupled to (e.g., threaded into, clamped onto, or otherwise fastened to) the forward surface 48 to seal the internal space 67. In the illustrated construction, the cover 72 is threaded into forward surface 48 and a seal 74 (e.g., an O-ring, a washer, etc.) is clamped between the second shoulder 69 and the cover 72 to prevent fluid exchange between the internal space 67 and the space 54. The cover 72 also defines an internal opening 76 opening along the central axis A and including a seal 78.
A bleed line 80 extends through the frame 44 for conveying lubricant from one portion of the internal space 67 to another portion of the internal space 67 (as described below). In the illustrated construction (see
As shown in
With reference to
As shown in
A piston (shown in
The second end 118 of the piston 114 is substantially cylindrical and has a diameter D4 (see
As shown in
As shown in FIGS. 1 and 8A-8D, the second end 118 of the piston 114 divides the internal space 67 into a first or forward chamber 134 and a second or rearward chamber 136. Lubricant is moveable between the first and second chambers 134, 136 along the bleed line 80, or alternatively, along a channel 138 (see FIG. 6D). As shown in
As shown in
During operation of the rotary tool 10, the tool engaging end 104 (or a fastener engaging element coupled to the tool engaging end 104) is positioned to matingly engage a fastener (e.g., a nut, a bolt, a screw, etc.). To tighten the fastener or thread the fastener into a work piece (not shown), the rotary tool 10 is operated in a forward mode and to loosen the fastener or unthread the fastener from the work piece, the rotary tool 10 is operated in a reverse mode.
To initiate operation of the rotary tool 10, an operator depresses the trigger 26, causing power in the form of compressed air or electricity to energize the motor 22 and to rotate the motor shaft 24 in a forward direction (represented by arrow 146 in
With reference first to
With reference to
As the piston 114 continues to rotate about the central axis A, the fastener 126 rides along the contoured end 122, moving the piston 114 forward along the central axis A to a forward-most position (shown in FIGS. 8B and 9B). When the piston 114 is in the forward-most position, forward portions of the arms 132 contact the base 106 of the output shaft 100. In the illustrated construction, the contoured end 122 of the notch 120 includes protrusion 147. In this construction, each time the piston 114 rotates about the central axis A, the fastener 126 engages the protrusion 147 once. More particularly, each time that the piston 114 rotates about the central axis A, the engagement between the protrusion 147 and the fastener 126 causes the arms 132 to contact the cams 108. In other constructions (not shown), the notch 120 can have two, three, or more protrusions 147 for causing the arms 132 to contact the cams 108 two or more times each time the piston 114 rotates about the central axis A.
With reference to
Additionally, after the impact between the cams 108 and the arms 132, the piston 114 begins to move rearwardly, disengaging the arms 132 from the cams 108. More particularly, as shown in
As the piston 114 continues to rotate about the central axis A, the pressure difference between the forward and rearward chambers 134, 136 forces lubricant from the rearward chamber 136, through bleed line 80, past valve 96, and into the forward chamber 134. In this manner, the pressure in the rearward chamber 136 is reduced, allowing the piston 114 to move axially to the rearward-most position. Lubricant continues to move along the bleed line 80 from the rearward chamber 136 to the forward chamber 134 until the pressure of the forward and rearward chambers 134, 136 is approximately equal. In the illustrated construction, the pressure in the forward and rearward chambers 134, 136 is approximately equal when the arms 132 pass across the cams 108.
Once the piston 114 returns to the rearward-most position, the piston 114 continues to rotate with the frame 44 about the central axis A until the engagement between the notch 120 and the fastener 126 causes the piston 114 to move forwardly along the central axis A. In the illustrated construction, the piston 114 rotates approximately 200 degrees about the central axis A before the fastener 126 engages the protrusion 147 to re-initiate forward motion of the piston 114. However, as explained above, in other constructions (not shown), the notch 120 can include two, three, or more protrusions 147. In these constructions, the piston 114 can rotate less than 200 degrees before the mating engagement between the fastener 126 and one of the protrusions 147 causes the piston 114 to move forwardly along the central axis A.
The constructions described above and illustrated in the drawings are presented by way of example only and are not intended as a limitation upon the concepts and principles of the present invention. As such, it will be appreciated by one having ordinary skill in the art, that various changes in the elements and their configuration and arrangement are possible without departing from the spirit and scope of the present invention as set forth in the appended claims.
For example, one having ordinary skill in the art will appreciate that the size and relative dimensions of the individual parts of the rotary tool can be changed significantly without departing from the spirit and scope of the present invention.
As such, the functions of the various elements and assemblies of the present invention can be changed to a significant degree without departing from the spirit and scope of the present invention.
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Number | Date | Country | |
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20040173364 A1 | Sep 2004 | US |