SAW, A SAW BLADE, A CONNECTION MECHANISM AND ASSOCIATED METHODS

Abstract

The present disclosure relates to a saw, comprising a drive, a first blade configured to oscillate about an axis perpendicular to a plane defined by a surface of the first blade, a second blade configured to oscillate about an axis perpendicular to the plane in a direction opposite to that of the first blade, and wherein gearing is provided between the drive and the first and second blades to reduce the speed transmitted from the drive to the blades. A saw blade, a connection mechanism for connecting a blade to a saw and associated methods are also provided.

Claims

1. A method of removing saw blades from a saw, the method comprising the steps of: moving a resiliently biased latch member of a blade from a first position in which it engages a mounting member of the saw to a second position in which it no longer engages the mounting member; and removing the blade axially from the mounting member.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The foregoing summary, as well as the following detailed description of illustrative embodiments of the devices and methods of the present application, will be better understood when read in conjunction with the appended drawings. For the purposes of illustrating the device and methods of the present application, there is shown in the drawings illustrative embodiments. It should be understood, however, that the application is not limited to the precise arrangements and instrumentalities shown. In the drawings:

[0020] FIG. 1A is a cut-away perspective view of a powered saw according to an embodiment of the present disclosure;

[0021] FIG. 1B is a sectional side elevation view of a powered saw similar to the powered saw illustrated in FIG. 1A, but constructed in accordance with an alternative embodiment;

[0022] FIG. 1C is a side elevation view of an eccentric shaft of the powered saw illustrated in FIGS. 1A-B;

[0023] FIG. 2 is a perspective view of a proximal end of a saw blade according to an embodiment of the present disclosure;

[0024] FIG. 3 is a perspective view of a mounting member according to an embodiment of the present disclosure;

[0025] FIG. 4A is a cut away perspective view of the connection mechanism according to an embodiment of the present disclosure, illustrating the blade shown in FIG. 2 engaged with connection mechanism shown in FIG. 3;

[0026] FIG. 4B is a bottom plan view of the connection mechanism illustrated in FIG. 4A;

[0027] FIG. 5 is a sectional perspective view of a portion of connection mechanism according to an embodiment of the present disclosure;

[0028] FIG. 6 is a bottom plan view of the proximal end of a saw blade shown in FIG. 2; and

[0029] FIG. 7 is a cross-section of the proximal end of the saw blade along the line B-B in FIG. 6.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0030] Referring to FIG. 1A, a powered saw 100 having a drive location that is configured to support a motor drive 110 that is operably connected to eccentric shaft 140 via gearing. The powered saw 100 can include the motor drive 110, for instance at the drive location as illustrated in FIG. 1A, or the drive location can define a receptacle 111 (see FIG. 1B) that is configured to receive, for instance removably receive, a drive, such as a motor drive. The saw 100 can include a handle portion or handpiece 102 and a cutting portion 104 spaced from the handle portion 102 along the longitudinal direction L. The saw 100 can include a housing 107 for carrying at least a portion of the drive 110 and gearing. The housing 107 can at least partially define the receptacle 111.

[0031] The saw 100, or cutting portion 104, can include a first blade 220 and a second blade 240. The first and second blade 220 and 240 includes a proximal end 252 and 352, respectively, each of which is configured to attach to the saw (detailed below), and a distal end 254 and 354, respectively, spaced from the proximal end 252 and 352 along the longitudinal direction L when the blades are attached to the saw 100. The proximal ends of the blades can define respective blade attachment portions. The first blade 220 includes a first or upper surface 256 and a second or lower surface 258 spaced from the first surface 256 along the transverse direction T. The transverse direction T can be substantially perpendicular to the longitudinal direction L of the saw 100. The blades 220,240 can extend along the longitudinal direction L and have a transverse directional component. Further, the second blade 240 includes a first or upper surface 356 and a second or lower surface 358 spaced from the first surface 356 along the transverse direction T. Each respective blade surfaces extend between the proximal end 252,352 and the distal end 254,354 of the blades 220, 240, and can define the respective planes that extend along the longitudinal direction L. The blades 220, 240 each comprise a cutting portion 221, 241 disposed at the distal end 254, 354 thereof, which is positioned distal to the blade attachments 320, 340 along the longitudinal direction L when the blade is connected to the saw 100. In order the cut an object, the first and second blades 220, 240 are configured attach to the saw 100 so as to oscillate about a similar axis, or alternatively, about a different axes. For instance, the first and second blades 220 and 240 can oscillate about an axis that is perpendicular to a plane defined by any of the respective surfaces of each respective blade, such that the blades oscillate in an oscillation direction O. As further detailed below, the first and second blades 220,240 oscillate in opposite directions.

[0032] Blades 220, 240 can be removably connected to the saw 100 by blade attachments 320, 340 which are configured to hold the blades 220, 240 in parallel planes that extend along the longitudinal direction L. The blade attachments 320, 340 each have a first pair of arms 320a and 320b and a second pair of arms 340b, 340b (FIGS. 1C and 4B) which surround the eccentric shaft 140 (see also FIG. 1C). The eccentric shaft 140 is disposed along a transverse direction T, which is perpendicular to the blades 220, 240 and the blade attachments 320, 340. The gearing is provided between the drive location and the first and second blades 220,240 to reduce the speed of oscillation of the blades 220,240. The gearing can include one or both of a planetary gear 120 and a 90° gear transmission 130.

[0033] In use, torque is transferred from the drive 110 via the planetary gear 120 and the 90° gear transmission 130 to rotate the eccentric shaft 140 about a central shaft axis 140a. As the shaft 140 rotates it converts rotational movement from the drive 110 to oscillation of the blades 220, 240 via the blade attachments 320 and 340. The blade attachments 320 and 340 define respective central axes 329 and 339 that are spaced from the central shaft axis 140a, and can be disposed opposite each other such that the central shaft axis 140a is disposed between the central axes 329 and 339. The eccentric shaft 140 is configured such that, as it rotates, it moves the first pairs of arms 320a and 320b, and a second pair of arms 340a and 340b of the attachment mechanism in opposite directions, thus oscillating the blades in opposite directions O relative to one another. The eccentric shaft 140 has a central portion 150, a first offset portion 152, and a second offset portion 154. The central portion 150 extends along the central shaft axis 140a. The first offset portion 152 second offset portions 154 extend along respective central offset axes (not shown) that lie in a similar plane with respective the central axes 339 and 329. The first pairs of arms 320a and 320b attach to the offset portion 154 and the second pair of arms 340a and 340b attach to offset portion 152. The blades 220, 240 are attached to the saw such that blades oscillate about the same axis, for instance the central shaft axis 140a, that extends along the transverse direction T. For instance, the central shaft axis 140a can extend along the transverse direction T and is substantially perpendicular to the first blade surfaces 256 and 258, and/or the second blade surfaces 356 and 358. The blades 220, 240 are securely connected to the blade attachments 320, 340, as described below, such that torque is transferred from the drive to the blades 220 and 240.

[0034] The planetary gear 120 achieves a reduction of the speed of the drive transmitted to the blades, and conversely an increase in torque. The ratio of reduction of speed along a direction from the drive 110 to the blades 220, 240 caused by the planetary gear is 1:3.9474, though it should be appreciated that the reduction of speed caused by the planetary gear can be configured as desired, for example between 1:1.1 and 1:10. The 90° gear transmission 130 can include a first or input gear 131, which can be a bevel gear, and a second or output gear 133, which can be a bevel gear, that is intermeshed with the first gear 131. The planetary gear 120 can be disposed between the drive location (and thus the motor drive 110) and the 90° gear transmission 130. The 90° gear transmission can be disposed between the planetary gear 120 and the eccentric shaft 140.

[0035] During operation, the first gear 131 rotates about a first axis of rotation 331 (FIG. 1A), and the second gear 133 rotates about a second axis of rotation 333 that is angularly offset, for instance oriented substantially 90°, with respect to the first axis of rotation 331. The first gear 131 is coupled to the drive 110 and configured to be driven to rotate by the drive 110 along the first axis of rotation, and the second gear 133 is coupled to the shaft 140, so as to drive the shaft to rotate about a corresponding axis of rotation that can be parallel or coincident with the second axis of rotation. Thus, the first gear 131 is disposed between the second gear 133 and the drive 110, and the second gear 133 is disposed between the shaft 140 and the first gear 131. The second gear 133 is configured to drive the eccentric shaft 140 to rotate, thereby causing the blades 220, 240 to reciprocally oscillate. The first gear 131 can be sized smaller than the second gear 133, and thus can have fewer teeth than the second gear 133. Accordingly, the second gear 133 rotates at a speed that is less than that of the first gear 131, and at a torque that is proportionally greater than that of the first gear 131. In accordance with one embodiment, the gear ratio can be as desired, for instance between 1:1.1 and 1:2. In accordance with the illustrated embodiment, the gear ratio can be 1:1.3846. The gear reduction of the 90° gear transmission produces a corresponding reduction of speed that is equal to the gear ratio, and a corresponding increase in torque output that is equal to the gear ratio. When the ratio of reduction of speed of the planetary gear is 1:3.9474 and the ratio of reduction of speed of the 90° gear transmission is 1:1.3846, the powered saw 100 produces a ratio of reduction in speed from the drive 110 to the eccentric shaft 140 of approximately ratio 1:5.4656. Although a planetary gear is illustrated, it would also be possible to use a bevel gear in its place.

[0036] The planetary gear 120 acts to provide high torque to the blades 220, 240 at low speed. In this way, the blades can be operated at low speed but with high torque. The blades cut with torque, not speed, and less heat is transmitted to bone. In addition, because the cutting is performed by two blades that are oscillating in opposite directions about the same axis, for instance the central shaft axis 140a, there is no resulting vibration of the bone or countertorque transmitted to the handpiece 102. Since no counter-torque is transmitted to the handpiece, handling of the tool is made easier, resulting in a more precise cut. The entry speed of the saw blades is between 2000 to 3000 rpm.

[0037] In an alternative embodiment of the saw, the planetary or bevel gear may be omitted so that there is a direct drive between the 90° gear transmission 130 and the blades 220, 240. For instance, referring to FIG. 1B, the powered saw 100 defines a receptacle 111 that can provide the drive location. The receptacle 111 is configured to receive a drive, such as a motor drive, at the drive location, the drive operable to rotate at a desired speed and produce a corresponding torque output. The powered saw 100 can be devoid of the planetary gear illustrated in FIG. 1A, such that the speed and torque output from the motor drive is communicated to the first gear 131 of the 90° gear transmission 130. Thus, the first gear 131 can be driven to rotate at substantially the same speed as the motor drive at substantially the same torque as is output from the motor drive. As described above, the first gear 131 can be sized smaller than the second gear 133, and thus can have fewer teeth than the second gear 133. Accordingly, the second gear 133 rotates at a speed that is less than that of the first gear 131, and at a torque that is proportionally greater than that of the first gear 131. In accordance with one embodiment, the gear ratio can be as desired, for instance between and including approximately 1:1.1 and approximately 1:5, including approximately 1:1.3846, approximately 1:1.5, or any suitable alternative gear ratio as desired. The gear reduction of the 90° gear transmission 130 produces a corresponding reduction of speed that is equal to the gear ratio, and a corresponding increase in torque output that is equal to the gear ratio. Furthermore, in accordance with the embodiment illustrated in FIG. 1B, the gear ratio of the 90° gear transmission 130 can define the gear ratio, and thus the speed reduction and torque increase, between the motor drive and the blades.

[0038] The output speed of the oscillation of the blades 220, 240 can be between 7000 to 10000 rpm, including 8000 rpm to 10000 rpm. In accordance with one embodiment of the powered saw 100, the speed of oscillation of the blades can be 7000 rpm.

[0039] The blades 220, 240 and the corresponding blade attachments 320, 340 may be symmetrical. Therefore, a saw 100 is provided that can have two identically configured blades. It should be appreciated that the blades can have different configurations as needed. For purpose of illustrating the configuration of first and second blades 220 and 240, only blade 220 will be further detailed below. It should be appreciated that the features described herein with respect to the first blade 220 are applicable to the second blade 240. Further, the features described herein regarding the blade attachment 320 are applicable to the blade attachment 340.

[0040] Referring to FIGS. 2, 3 and 6, the proximal end 252 of the blade 220 a spanner shaped head 222. The spanner shaped head 222 defines an opening 223 that extends along a longitudinal direction L. For instance, the head 222 has two arms 223a and 223b that are spaced apart and extend substantially parallel with respect one another. The arms 223a and 223b at least partially define and surround the opening 223. The proximal end 252 of the blade 220 also comprises a projection 227 that extends from the surface 258 (or 256) of blade 220 along a transverse direction T. The projection 227 can be a latch which is milled out from the blade 220 and is bent downwards along the transverse direction T so that it is resiliently biased into a position in which it extends from the surface 258 of the blade 220.

[0041] Referring to FIG. 3, the blade attachment 320 includes a mounting member 321, for instance a mounting portion 321. The mounting portion 321 has a receiving surface 322, and a raised portion 323, for instance a portion that raised relative to the receiving surface 322 along the transverse direction T. The raised portion 323 is configured to correspond to the shape of the opening 223 of blade 220 shown in FIG. 2. The blade 220 can thus be slid into engagement with the receiving surface 322 such that the arms 223a and 223b surround the raised portion 323 of the mounting portion 321 (FIG. 4A) as shown in FIG. 4.

[0042] Referring to FIGS. 2, 6 and 7, the blade 240 can define an inner surface 225, the at least partially defines the opening 223. The inner surface 225 can extend from the upper blade surface 256 to the lower blade surface 258, and along the spaced apart arms 223a and 223b to define a U-shape. The inner surface 225 of arms 223a, 223b of the blade 220 are angled relative to the lower surface 258, or plane of the blade 220. In an embodiment, the angle of the inner surface 225 relative to the plane of the blade is about 60°. As can be seen in FIG. 3, the mounting portion 321 can also define an outer surface 325 that extends from the raised portion 323 to the receiving surface 322. The outer surface 325 of the raised portion 323 is angled relative the raised portion 323 to define a complementarily angle with respect to the inner surface 225 of blade 220. Thus, the outer surface 325 of the raised portion 323 and the inner surface 225 of the arms 223a and 223b interlock when the blade opening 223 is slid into close engagement with the raised portion 323 as shown in FIGS. 4A-B. As a result, movement relative to the surface of the blade is effectively prevented so that vibration between the two blade surfaces is minimized.

[0043] Referring to FIGS. 2 and 3, the receiving surface 322 has an aperture 327 that is positioned distal to the raised portion 323 along the longitudinal direction L. The aperture 327 is configured to receive at least a portion of the projection 227. The aperture 327 can act as a latching surface, against which the projection 227 of the blade 220 latches once the blade 220 has been slid into the position shown in FIGS. 4A-B. From this position, the blade 220 cannot be moved axially, for instance, along the longitudinal direction L out of engagement with the mounting portion 321. The latching projection 227 is resiliently biased towards the latching surface. However, the latching projection 227 is accessible through the aperture 327 by means of an opening in the opposing side of the mounting portion 321 to the receiving surface 322 (see for example opening 349 in FIG. 5). As a result, it is possible to release the latching projection 227 from its first position in the aperture 327 into which it is resiliently biased as shown in FIGS. 4A and 4B, into a second position in which the projection 227 no longer latches against the latching surface. When projection is in the second position, the blade 220 is no longer prevented from moving axially relative to the mounting portion 321 and can be moved out of engagement therewith. Thus, the blade 220 is readily removable from engagement with the mounting member 321, and thus, the powered saw 100. As shown in FIG. 5, the second blade 240 can have a latching projection 247 which can engage the aperture 347 of the blade attachment 340.

[0044] It will of course be understood that the present disclosure has been described above purely by way of example, and that modifications of detail can be made within the scope of the present disclosure.