U.S. patent number 3,797,497 [Application Number 05/229,680] was granted by the patent office on 1974-03-19 for drill like driving device.
This patent grant is currently assigned to Stryker Corporation. Invention is credited to Paul E. Crim, Wayne Warfield.
United States Patent |
3,797,497 |
Crim , et al. |
March 19, 1974 |
DRILL LIKE DRIVING DEVICE
Abstract
A driving device including a right-angle handpiece assembly
having a casing containing an input shaft, an output shaft and
means drivingly connecting same. A bone drill attachment is
connectible to the handpiece assembly and includes a cylindrical
extension mountable upon the output end of the casing and
concentric inner and outer drill bits which project from said
extension. The inner drill bit is connectible to the output shaft
by a pair of clutch mechanisms which are normally spring-biased
into a disconnected position. The outer drill bit normally rotates
with the inner drill bit but is permitted to move axially and
angularly relative to the inner drill bit through a predetermined
distance. The cutting end of the inner drill bit extends axially
beyond the cutting end of the outer drill bit. Alternately, a wire
driving attachment can be connected to the handpiece assembly and
includes a chuck structure mountable upon the output end of the
casing and drivingly connectible to the output shaft. The chuck
structure has a continuous opening therethrough which aligns with a
through opening in the casing for receiving therein an elongated
member, such as a wire.
Inventors: |
Crim; Paul E. (Portage, MI),
Warfield; Wayne (Kalamazoo, MI) |
Assignee: |
Stryker Corporation (Kalamazoo,
MI)
|
Family
ID: |
22862252 |
Appl.
No.: |
05/229,680 |
Filed: |
February 28, 1972 |
Current U.S.
Class: |
606/173;
74/665S |
Current CPC
Class: |
B23Q
5/045 (20130101); A61B 17/1633 (20130101); A61B
17/1697 (20130101); A61B 17/1617 (20130101); Y10T
74/19112 (20150115); A61B 2017/00544 (20130101) |
Current International
Class: |
A61B
17/16 (20060101); B23Q 5/00 (20060101); B23Q
5/04 (20060101); A64b 017/16 (); F16h 037/06 () |
Field of
Search: |
;74/416,665S
;128/305,310,312 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Pace; Channing L.
Attorney, Agent or Firm: Woodhams, Blanchard & Flynn
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. In a drill assembly having casing means, input shaft means
rotatably supported within said casing means, and output shaft
means rotatably supported within said casing means and connected to
said input shaft means for rotation thereby, the combination
comprising:
a tubular, cylindrical extension on said casing means coaxial with
said output shaft means;
outer cylindrical bit means having a coaxial cylindrical opening
extending therethrough, said outer bit means being rotatably
supported relative to said extension;
inner bit means snugly but slidably disposed within said outer bit
means, said inner bit means having a workpiece engaging end
extending axially beyond the corresponding end of said outer bit
means;
cooperating stop means on said inner and outer bit means permitting
limited relative axial movement therebetween;
engageable clutch means coacting between said inner bit means and
said output shaft means and adapted, when engaged, to rotate said
inner and outer bit means in response to rotation of said output
shaft means; and
said clutch means including first and second disengageable clutch
devices drivingly connected in series and each including resilient
means normally maintaining same in a released condition, whereby
engagement of both of said clutch devices is necessary to permit
said inner and outer bit means to be rotated in response to
rotation of said output shaft means, engagement of said clutch
devices being effected when said end of said inner bit means is
pressed firmly against a workpiece.
2. A drill assembly according to claim 1, wherein said casing means
includes first and second tubular portions fixedly connected
together at right angles to one another, and wherein said input and
output shaft means are respectively rotatably supported within said
first and second tubular portions and are interconnected by gear
means.
3. A drill assembly according to claim 1, wherein said stop means
comprises an elongated helical slot in one of said bit means and a
pin rigidly secured to and extending radially from the other of
said bit means into said slot for permitting only limited axial and
rotational movement between said inner and outer bit means, said
helical slot being oriented in a direction relative to the
rotational direction of said inner bit means for causing said inner
bit means to be moved axially for causing disengagement of said
clutch means when the external load on said inner bit means is
removed but an external load is still present on said outer bit
means.
4. A drill assembly according to claim 1, wherein at least one of
said clutch devices includes a first annular sleeve member
rotatably supported within said cylindrical extension, said first
sleeve member having an ejector pin slidably supported thereon for
axial movement thereof in a direction substantially parallel with
the longitudinal direction of said cylindrical extension, and said
resilient means associated with said one clutch device comprising
spring means coacting between said first sleeve member and said pin
for normally urging said pin outwardly from one end of said first
sleeve member, said one end of said sleeve member also having
projection means extending axially outwardly thereof; and
said one clutch device also including a second sleeve member
rotatably supported within said cylindrical extension and spaced
axially of said first sleeve member, said second sleeve member
having rib means formed thereon which extends both axially and
radially thereof, said rib means extending axially in a direction
toward said one end of said first sleeve member, whereby relative
axial movement of said first and second sleeve members toward one
another in opposition to the urging of said spring means causes
said projection means to axially overlap said rib means for
providing a torque transmitting connection therebetween.
Description
FIELD OF THE INVENTION
This invention relates in general to a drill-like driving device
and, in particular, to an improved device which includes a
right-angle handpiece assembly which can have several different
attachments mounted thereon, such as a bone drilling attachment or
a wire driving attachment for permitting drilling or perforation of
a bone in a human or other animate.
BACKGROUND OF THE INVENTION
A number of drills and drill bits have been developed in the past
for the purpose of providing openings in bone structure, such as
the skull, and a drill bit construction of this type is disclosed
in the U.S. Pat. No. 2,842,131. The purpose of this drill structure
is to perform the drilling operation with a minimum of bone damage
and without perforating the meninges so that the brain tissues
under the meninges will not be contaminated with bone fragments
produced during the drilling operation.
Heretofore, however, it has been the common practice to furnish a
drill bit assembly, as shown in the aforementioned Smith patent,
which is driven by a driver or handpiece, not especially adapted
for this type of surgical operation. Moreover, insofar as I am
aware, no complete drill assembly has been furnished for easy
connection to and operation by a highspeed air motor and having the
features of automatically disconnectible clutch means as well as a
right-angle drive.
Accordingly, the primary object of this invention is the provision
of a drill device having clutch means for automatically
disconnecting a pair of concentric drill bits from the source of
rotational power and, moreover, having a simple means for
disconnecting the extended bits from the handpiece.
A further object of this invention is the provision of a drill
device having a handpiece which can be quickly and easily adapted
for other uses, such as a wire driver, thereby reducing inventories
required for assembling different types of surgical
instruments.
Other objects and purposes of this invention will become apparent
to persons familiar with this type of equipment upon reading the
following descriptive matter and examining the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded perspective view of the improved handpiece
assembly constructed according to the present invention.
FIG. 2 is a central, cross-sectional view of the handpiece
assembly.
FIG. 3 is a side elevational view illustrating therein the
handpiece assembly of FIG. 2 having a bone drill attachment mounted
thereon.
FIG. 4 is an exploded, perspective view of the bone drill
attachment of FIG. 3 and illustrating its relationship to the
handpiece.
FIG. 5 is a central, sectional view of the bone drill attachment
and illustrating the manner in which same is mounted on the output
end of the handpiece assembly, the bone drill attachment being
illustrated in its released or nondriving position.
FIG. 6 is a central, sectional view similar to FIG. 5 and
illustrating the bone drill attachment in its engaged driving
condition.
FIG. 7 is a fragmentary, sectional view illustrating the
operational position of the bone drill when it breaks through a
large bone, such as a cranial bone.
FIG. 8 is a sectional view taken along the line VIII--VIII of FIG.
5.
FIG. 9 is a side elevational view, partially in cross section,
illustrating the improved handpiece assembly of FIG. 2 having a
wire driving attachment mounted thereon.
For convenience in reference only, the terms "upper," "lower,"
"rightward" and "leftward" will have reference to the device and
parts thereof, particularly as appearing in FIGS. 2, 3, 5 and 9.
The terms "output" and "input" will have reference to the lower end
and right end, respectively, as appearing in FIGS. 2, 3 and 9. The
terms "inner" and "outer" will have reference to the geometric
center of the device and designated parts thereof. Said terminology
will include the words above specifically mentioned, derivatives
thereof and words of similar import.
SUMMARY OF THE INVENTION
The objects and purposes of the invention, including those set
forth above, have been met by providing a drill-like driving device
which includes an improved right-angle handpiece assembly having
input and output shafts arranged within a casing at right angles to
each other and interconnected by gear means. The input shaft
includes a reduction gear assembly therein whereby the input shaft
can be connected to a high-speed air motor and the output shaft can
be driven at a low rotational speed. The handpiece assembly is
connectible to a bone drill attachment which is mountable on the
output end of the casing and includes drive shaft means which is
drivingly connectible to the output shaft of the handpiece
assembly. The drive shaft means of the bone drill attachment
includes a pair of normally disconnected clutch assemblies
connected in series between the output shaft of the handpiece
assembly and a pair of concentric drill bits. The drill bits are
normally rotated together but are mounted for permitting limited
axial and annular displacement therebetween for permitting the
rotation of the drill bits to be stopped under emergency situations
wherein the clutch assemblies do not release. Alternately, the
handpiece can have a wire driving attachment mounted on the output
end thereof, which wire driving attachment in one embodiment
comprises a chuck mounted on the casing and having a wire engaging
member connected to the output shaft for permitting rotation of an
elongated wire, which wire extends through the chuck and the casing
for permitting driving of a wire of substantial length.
DETAILED DESCRIPTION
FIGS. 1 and 2 illustrate therein the improved right angle handpiece
assembly 11 of the present invention, which assembly is designed to
permit its use with several different drill-like attachments. The
handpiece assembly 11 particularly the like. suitable for use with
a bone drill attachment 12, as illustrated in FIG. 3. However, the
handpiece assembly 11 can also be utilized with a wire driving
attachment 13 as illustrated in FIG. 9.
Considering first the handpiece assembly 11, as illustrated in
FIGS. 1 and 2, same includes a substantially T-shaped casing 16
having an elongated tubular handle 17 fixedly connected to an
elongated tubular gear housing 18. The gear housing 18, for
purposes of convenience, is constructed of two pieces and includes
a main housing part 19 and an end cap 21 which is fixedly, here
threadedly, connected to the upper end of the main housing part 19.
The gear housing 18 has a coaxial cylindrical opening 22 extending
therethrough, which opening has cylindrical portions 23 and 24 of
reduced diameter at the opposite ends thereof. The end of the
housing 18 opposite the end cap 21 is also formed with a reduced
cylindrical hub 26 on the exterior thereof which is formed with a
flat 27 thereon. Gear housing 18 also has a further opening 28
provided in the side thereof and partially defined by an outwardly
extending circular boss 29 which, in the illustrated embodiment, is
threaded to permit same to be fixedly connected to the handle 17.
The opening 28 is thus substantially aligned with a central opening
31 which extends longitudinally of the handle 17.
The gear housing 18 has a drive or output shaft 32 supported for
rotation therein by bushings 34 and 36 disposed adjacent the
opposite ends of the gear housing. The drive shaft 32 is of tubular
construction and has a central opening 33 extending axially
throughout the complete length thereof. The opposite ends of the
tubular drive shaft 32 are provided with enlarged internal recesses
37 which result in the formation of an axially facing shoulder 38.
The tubular drive shaft 32, in the region of each recess 37, is
provided with a pair of diametrically opposite slots 39 which are
of a substantially L-shaped configuration and extend axially
inwardly from the free ends of the shaft. The enlarged recesses 37
and slots 39 thus function as half of a conventional bayonet-type
coupling for permitting either end of the drive shaft 32 to be
drivingly coupled to a further shaft or member.
A driven face gear 41 is concentrically disposed within the opening
22 of the gear housing 18, which face gear 41 is positioned in
surrounding relationship to and is nonrotatably connected to the
drive shaft 32 by any conventional means, such as a key 42. The
face gear 41 is rotatably supported on the gear housing 18 by means
of an intermediate thrust bearing 43.
Considering now the handle 17, same includes an input shaft
assembly rotatably supported therein and provided for drivingly
connecting the output shaft 32 to an external power source, such as
an air motor. The input shaft assembly includes an input shaft 46
substantially coaxially disposed within the opening 31 and
rotatably supported within the handle 17 by conventional
anti-friction bearings 47. The ball bearings 47 are supported on an
annular bearing retainer 48 which has one end thereof fixedly
connected to a speed reducer housing 49 by a conventional set screw
51. The housing 49 contains therein a conventional planetary
gear-type speed reducer which has a rotatable drive shaft 52
drivingly connected to the input shaft 46 by means of an
intermediate coupling 53. A conventional speed reducer 54 is
drivingly connected between the shaft 52 and a driven shaft 55. The
driven shaft 55 has a spur gear 56 nonrotatably secured thereto.
Gear 56 has axially elongated teeth formed on the periphery thereof
and functions as a drive gear, being disposed in continuous meshing
engagement with the driven face gear 41.
The speed reducer housing 49 has an annular shoulder or flange 57
formed thereon, which flange is clampingly held between the boss 29
and an internal shoulder formed in the handle 17 for fixedly
securing the speed reducer housing 49 in position within the
handle. The input shaft 46 is provided with a conventional slotted
coupling portion 58 on the free end thereof adapted to engage the
output end of a suitable drive mechanism or power source, such as a
flexible drive member connected to an air motor, not
illustrated.
Considering now the bone drill attachment 12, as illustrated in
FIG. 4, same includes a housing assembly 61 which is adapted to be
connected to the handpiece assembly 11. The housing assembly 61 has
disposed therein first and second clutch assemblies 62 and 63
connected in series with one another, with the second clutch
assembly 63 in turn being drivingly connectible to a clutch drive
shaft assembly 64. The latter in turn is drivingly connected to a
cutter assembly 66.
Referring now to FIGS. 5 and 6, the housing assembly 61 includes a
cylindrical extension sleeve 67 having an enlarged upper section 68
of sufficient inside diameter to telescope over the cylindrical hub
26. The extension sleeve 67 is releasably connected to the
handpiece casing by a set screw 69 which engages the flat 27 formed
on the casing. An elongated cylindrical bushing 71 is secured
within the central portion of the extension sleeve 67, as by means
of a press fit, and a further annular bushing 72 is secured within
the upper end of the extension sleeve 67. The bushings 71 and 72
respectively rotatably support the second and first clutch
assemblies 63 and 62.
The first clutch assembly 62 includes a sleevelike rear clutch
element 73 rotatably supported within the bushing 72 and having a
tubular shaft 74 fixedly secured, as by being press-fitted, within
the interior thereof. The upper end of shaft 74 extends upwardly
beyond the clutch element 73 so as to be insertable into the
internal recess 37 formed in the end of the drive shaft 32. The
upper end of the tubular shaft 74 has a pair of diametrically
opposed flanges or ribs 76 extending radially outwardly therefrom
and adapted to be slidably received within the elongated straight
portions of the slots 39 formed within the drive shaft 32. An
ejector pin 77 is slidably supported within and extends through the
tubular shaft 74 and has an enlarged stop or abutment 78 fixedly
secured to the upper end thereof, with a further abutment 79 being
fixedly secured to the lower end thereof. A conventional
compression spring 81 is disposed in surrounding relationship to
the ejector pin 77 and is confined between the tubular shaft 74 and
the lower abutment 79 for normally urging the ejector pin 77 in a
downward direction.
The rear clutch assembly 62 also has a pair of clutch projections,
namely a pair of diametrically opposed pins 82, fixedly secured to
and projecting downwardly from the lower end of the clutch element
73. The pins 82 are adapted to coact with the second clutch
assembly 63 for permitting same to be clutchably engaged with and
drivingly connected to the first clutch assembly 62. The second
clutch assembly 63 includes a sleevelike front clutch element 83
rotatably supported within the bushing 71 and having a slot 84
extending diametrically across the upper axial end face thereof. An
elongated key 86 of substantially rectangular cross section is
fixedly positioned, as by being press-fitted, within the slot 84
and is disposed so as to be normally abuttingly engaged by the
lower end of the ejector pin 77 associated with the first clutch
assembly 62. The front clutch element 83 has a central opening 87
extending therethrough, the lower end of which is enlarged. A
retainer sleeve 88 is disposed within the lower end of the opening
87 and is fixedly secured to the front clutch element 83. An
elongated ejector pin 89 is disposed within the opening 87 and is
slidably supported by the retainer sleeve 88 and the clutch element
83. Ejector pin 89 is resiliently urged downwardly by a compression
spring 91 and projects beyond the retainer sleeve 88. The spring 91
is disposed within the enlarged portion of the opening 87 and is
confined between the clutch element 83 and a collar 92 which is
fixedly secured to the ejector pin 89 intermediate the ends
thereof.
The second clutch assembly 63 also has clutch projections, namely a
pair of diametrically opposed clutch pins 93, fixedly secured to
and projecting axially downwardly from the lower end of the front
clutch element 83. The clutch pins 93 are disposed for clutching
engagement with the clutch drive shaft assembly 64.
The clutch drive shaft assembly 64 includes a sleevelike drive
shaft 96 on which is press-fitted a surrounding sleeve 97, which
sleeve is rotatably supported within an annular bushing 98. Bushing
98 is stationarily disposed within a surrounding cuplike end cap 99
which is disposed within the lower end of the cylindrical extension
sleeve 67 and is fixedly secured thereto, as by a pin 101.
The clutch drive shaft 96 has an annular flange 102 adjacent the
upper end thereof, which flange has a slot 103 extending
diametrically across the upper axial end face thereof. An elongated
key 104 of substantially rectangular cross section is fixedly
disposed within the slot, as by being press-fitted therein, and is
positioned so as to be abuttingly engaged by the lower end of the
ejector pin 89. The clutch drive shaft 96 also has a central
opening 106 formed therein, which opening permits reception therein
of a portion of the cutter assembly 66.
Considering now the cutter assembly 66, same includes an inner
cutter or drill bit 107 and an outer tubular cutter or drill bit
108 rotatably supported on the inner cutter 107. The outer cutter
has a small helical slot 109 formed in the sidewall thereof and
through which extends a pin, namely a screw 111. The screw 111 is
fixedly secured to the inner cutter 107 and extends radially
outwardly thereof. The slot-and-pin connection provides the only
direct driving connection between the cutters, while it also
permits the outer cutter 108 to have a limited rotational and axial
displacement relative to the inner cutter 107.
The outer cutter 108 has an annular flange 112 at the rearward end
thereof which is adapted to move into abutting engagement with the
lower end of the bushing 98, whereas downward movement of the outer
cutter 108 is limited by an annular flange 113 which is provided on
the lower end of the inner cutter 107, which inner cutter projects
axially downwardly beyond the lowermost end of the outer cutter
108. The lower axial end faces of the inner and outer cutters are
both provided with cutting edges and surfaces which are
conventional and thus further description thereof is not believed
necessary.
To permit the cutter assembly 66 to be drivingly connected to the
clutch drive shaft assembly 64, the inner cutter 107 is provided
with an elongated shank portion which is adapted to be slidably
inserted into the opening 106 formed within the clutch drive shaft
96. The upper free end of the inner cutter 107 has a substantial
flat formed thereon which results in the formation of an upwardly
extending projection 114 having a cross section approximating or
slightly greater than half of a cylinder. This projection 114 is
adapted to align with and axially overlap a key 116 which is
fixedly secured to the drive shaft 96. The key 116 has a cross
sectional profile which is substantially equal to or slightly less
than half of a cylinder, so that the key 116 and the projection 114
thus substantially comprise a cylinder when overlapped to thus
provide a rotatable driving relationship between the shaft 96 and
the inner cutter 107. The cutter 107 also has a friction ring 117
disposed in surrounding relationship therewith and positioned for
frictionally engaging the inner periphery of the drive shaft 96 for
holding the shank of the inner cutter 107 within the drive shaft
96.
OPERATION
The operation of the drilling device 10, particularly when the bone
drill attachment 12 has been attached to the handpiece assembly 11,
will be briefly described to insure a complete understanding
thereof.
Prior to operational use, the bone drill attachment 12 is secured
to the handpiece assembly 11 by positioning the large end 68 of the
cylindrical extension sleeve 67 over the cylindrical hub 26, the
bone drill attachment being secured to the handpiece by the set
screw 69. A suitable power source is drivingly connected, as by a
flexible power transmitting element, to the coupling portion 58 of
the handpiece input shaft 46. This thus provides a power
transmitting drive connection between the input shaft 46 of the
handpiece and the rear clutch element 73 of the bone drill
attachment 12.
After the bone drill attachment 12 has been secured to the
handpiece 11, the cutter assembly 66 is disposed in a disengaged or
nonrotatable position since all of the clutches in the bone drill
attachment are released, being in the position illustrated in FIG.
5. The spring 81 of the first clutch assembly causes the ejected
pin 77 to be resiliently urged downwardly so that the lower end of
the pin engages the key 86, whereby the ejector pin 77 pushes the
second clutch assembly 63 downwardly within the bushing 71 so that
the clutch pins 82 are axially spaced and disengaged from the key
86. The ejector pin 89 of the second clutch assembly is also
resiliently urged downwardly by the spring 91 so that the lower end
of the pin 89 engages the key 104 and pushes the clutch shaft
assembly 64 downwardly so that the key 104 is also axially spaced
and disengaged from the clutch pins 93. The downward movement of
the clutch shaft assembly 64 also causes the inner cutter 107 to be
in its lowermost or fully extended position, as illustrated in FIG.
5. The outer cutter assembly 108, being connected to the inner
cutter 107 solely by the pin and slot connection 109 and 111, will
be disposed adjacent the flange 113 or adjacent the bushing 98,
depending upon the orientation of the overall drilling assembly,
since the cutter 108 will move axially of the cutter 107 due to the
effect of its own weight. The initial position of the cutter 108,
when the device is inoperative, is immaterial to the successful
operation of the drilling apparatus.
When a drilling operation is to be performed, the drill assembly 10
is positioned, as shown in FIG. 6, so that the lower end of the
inner cutter 107 engages the surface of a bone 121, such as a
cranial bone. The drive shaft 32 of the handpiece assembly may now
be rotated by energizing the external power source which is
attached to the coupling portion 58. By pressing downwardly on the
handle 17, the cutter assembly 66 is moved upwardly until the outer
cutter 108 substantially engages the lower end of the bushing 98.
This upward movement of the cutter assembly also causes the clutch
shaft assembly 64 to be slidably moved upwardly in opposition to
the urging of the spring 91, whereby the ejector pin 99 is
depressed in an upward direction so that the key 104 thus moves
into a position wherein it is disposed between and axially overlaps
the clutch pins 93. This thus results in the second clutch assembly
63 and the clutch shaft assembly 64 being substantially
nonrotatably interconnected. Downward pressing on the handle 17
also causes the second clutch assembly 63 to be moved upwardly
toward the first clutch assembly 62 in opposition to the urging of
the spring 81, whereby ejector pin 77 is thus depressed to permit
the key 86 to be positioned between and in axially overlapping
relationship with the clutch pins 82. This thus results in the
first clutch assembly being nonrotatably and drivingly connected to
the second clutch assembly. Since the first clutch assembly is in
turn nonrotatably connected to the drive shaft 32 due to the
engagement of the flanges 76 within the bayonet slots 39, the
rotation of the drive shaft 32 is thus transmitted to the inner
cutter 107 causing rotation of same. The pin 111 secured to the
cutter 107 in turn causes a corresponding rotation of the outer
cutter 108.
When the drilling operation is being performed on the bone 121, the
bone drill attachment is disposed in driving engagement
substantially as illustrated in FIG. 6. Since the inner cutter 107
extends below the outer cutter 108, the inner cutter performs the
initial cutting operation and results in the formation of a hole of
a predetermined diameter, which hole is then subsequently enlarged
by the rotation of the outer cutter 108. The hole is thus drilled
in a two-step sequence due to the axial spacing between the inner
and outer cutters. The drilling will continue, due to the urging of
the operator, until the inner cutter 107 cuts through the bone, as
illustrated in FIG. 7. However, the outer cutter 108 has not yet
fully cut through the bone 121 and is thus supported on a narrow
annular shelf of bone 123. Due to the downward pressure of the
operator on the handle 17, and due to the engagement of the outer
cutter 108 with the bone shelf 123, a substantial frictional
torsional resistance is imposed on the outer cutter 108, whereas
substantially no torsional resistance is imposed on the cutter 107
since it has passed through the bone 121. Accordingly, the driving
torque imposed on inner cutter 107 causes the pin 111 to engage the
side of the slot 109, thereby causing the inner cutter 107 to be
cammed downwardly into the position illustrated in FIG. 7, which
downward camming of the inner cutter 107 also permits the two
clutch connections to be disconnected due to the resilient urging
of the springs 81 and 91. The transmission of torque to the inner
cutter is thus substantially instantly terminated. Further, since
the outer drill bit 108 is still supported on the bone shelf 123,
this thus prevents the inner and outer cutters from being pressed
inwardly, thereby preventing an inadvertent puncturing of the
meninges 122 which covers the brain.
While the operation as described above results in the disconnection
of the inner cutter 107 due to the camming action created by the
pin and slot 109 and 111, nevertheless the termination of torque
transmission to the inner cutter 107 may also occur due to the
urging of the springs 81 or 91. Particularly, when the inner cutter
107 initially cuts completely through the bone 121, the springs 81
or 91 may then possess sufficient force to cause the inner cutter
107 to be extended to thus drivingly disconnect one or both of the
clutch connections. Whether the springs cause the actual initial
disconnection of the clutch assemblies, or whether the initial
downward movement of the cutter 107 is caused by the pin-and-slot
arrangement, depends upon the size of the springs and the amount of
friction possessed by the overall device. However, it will be
readily apparent that the pin-and-slot connection and the clutch
springs effectively function as backup systems for one another so
that one or the other will initially release, whereupon failure of
one of the devices to release will in turn result in the release of
the other. Further, while only a single clutch could be provided,
the provision of two clutch devices also provides a safety feature
in that if one clutch device fails to release, the other clutch
device will release to insure stoppage of the drill. The present
invention thus provides three disconnectible couplings connected in
series to positively insure that the cutting bits will be
positively stopped as soon as the inner cutter penetrates the
cranial bone to thus prevent puncturing of the meninges which
covers the brain.
MODIFICATION
FIG. 9 illustrates therein a modification of the present invention
wherein the handpiece assembly 11 of FIGS. 1 and 2 is provided with
a wire driving attachment 13 mounted thereon. Particularly, in the
illustrated embodiment, the wire driving attachment 13
substantially comprises a conventional Jacobs chuck which has a
chuck body 131 rotatably mounted within a sleevelike body 128 which
is mounted on and secured to the cylindrical hub portion 26 of the
handpiece casing by a set screw 128. The chuck body 131 supports
therein an annular jaw actuating member 132. A plurality of
circumferentially spaced and radially movable jaws 133 are mounted
within the member 132 and are actuated in a conventional manner for
permitting the jaws to be radially moved into clamping engagement
with an elongated member, such as an elongated wire 137. The chuck
body 131 also has a hollow shaft portion 134 extending from the
rearward end thereof, which shaft portion is adapted to extend into
the end of the drive shaft 32 and is provided with one or more
radially projecting pins 136 thereon which extend into the bayonet
slots 39 for nonrotatably connecting the chuck body 131 and the
jaws 133 to the drive shaft 32.
In operation of the wire driving device illustrated in FIG. 9, the
wire 137, which is generally of an elongated length, is extended
through the opening 33 formed in the drive shaft 32 and is clamped
by the jaws 133 so that a predetermined length of wire extends
outwardly from the jaws. Upon operation of the device, whereupon
the rotation of the drive shaft 32 is transmitted to the jaws 133,
the wire is operated substantially as a drill and is rotatably
drilled into a bone. After the predetermined length of wire has
been drilled into the bone, the chuck is released and the overall
device lifted upwardly to permit a further amount of wire to pass
through the chuck, whereupon the chuck is then again retightened
onto the wire and a further length of wire is then drilled into the
bone. This procedure is repeated until the desired length of wire
has been inserted into the bone.
Thus, as is apparent from the above-described structure and
operation, the handpiece 11 of the present invention, as
illustrated in FIGS. 1 and 2, is highly desirable since it can be
utilized interchangeably with many different types of attachments,
such as the bone drill attachment and the wire driving attachment.
Further, while the above description has illustrated the
attachments as mounted on one end of the drive shaft 32, it will be
readily apparent that all of the attachments could likewise be
secured to the handpiece so as to be drivingly connected to the
opposite end of the drive shaft 32 (the upper end in FIG. 2),
thereby permitting rotation of a tool or driven element in the
opposite direction. The desirable handpiece thus is interchangeable
in that the attachments can be attached to the opposite ends of the
drive shaft to thus permit a driven element to be rotated in
opposite directions.
Although a particular preferred embodiment of the invention has
been disclosed in detail for illustrative purposes, it will be
recognized that variations or modifications of the disclosed
apparatus, including the rearrangement of parts, lie within the
scope of the present invention.
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