U.S. patent number 3,554,088 [Application Number 04/773,886] was granted by the patent office on 1971-01-12 for air tool.
This patent grant is currently assigned to James Henry Bruyn. Invention is credited to Charles D. Bruyn.
United States Patent |
3,554,088 |
Bruyn |
January 12, 1971 |
AIR TOOL
Abstract
An air tool which incorporates a plurality of pistons connected
to a common elongated rod, each piston being received within one of
a series of aligned cylinders and communicated with a source of
pressurized air whereby the pressurized air will act equally upon
the multiple pistons and provide for a substantial amplification of
the operating force derived from the pressurized air. The two flow
paths provided comprise one extending longitudinally through the
piston rod itself and the other surrounding the cylinders within a
cylinder enclosing housing. Also, with selected ones of the piston
receiving cylinders, one way check valves can be provided for
enabling the creation of a vacuum upon a forward stroke so as to
assist in amplifying the force of the return stroke.
Inventors: |
Bruyn; Charles D. (Vails Gate,
NY) |
Assignee: |
Bruyn; James Henry (Newburgh,
NY)
|
Family
ID: |
25099628 |
Appl.
No.: |
04/773,886 |
Filed: |
November 6, 1968 |
Current U.S.
Class: |
92/128;
29/243.523; 91/533; 92/111; 92/130B; 92/151 |
Current CPC
Class: |
F15B
11/0365 (20130101); B25C 1/04 (20130101); B21J
15/105 (20130101); F15B 2211/30525 (20130101); F15B
2211/7056 (20130101); Y10T 29/53739 (20150115); F15B
2211/40515 (20130101); F15B 2211/46 (20130101); F15B
2211/423 (20130101); F15B 2211/324 (20130101) |
Current International
Class: |
B21J
15/06 (20060101); B25C 1/04 (20060101); B21J
15/00 (20060101); F15B 11/00 (20060101); F15B
11/036 (20060101); F15b 011/06 (); F01b
007/00 () |
Field of
Search: |
;91/413,411A
;92/151,146,128 ;60/57,62,60 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Geoghegan; Edgar W.
Claims
I claim:
1. A force amplifying tool comprising a series of longitudinally
aligned cylinders, a piston operatively disposed in each cylinder,
an elongated piston rod extending slidably through said cylinders
and engaged with said pistons, one end of said rod being adapted to
mount a workhead, each piston defining forward and rear chambers in
the corresponding cylinder, first fluid passage means communicating
with all of the forward chambers, second fluid passage means
communicating with at least a major number of the rear chambers,
and an elongated tubular body enclosing said cylinders and fluid
passage means, one of said fluid passage means being defined
longitudinally through said piston rod, said rod having laterally
directed holes therein communicating the interior fluid passage
means with the corresponding chambers, the other of said fluid
passage means being defined about said cylinders between the
cylinders and the tubular body, and fluid passing holes
communicating said other fluid passage means with the corresponding
chambers, said elongated piston rod being formed of a plurality of
releasably interconnected hollow rod sections, at least the
majority of said pistons being mounted between adjacent rod
sections, each cylinder being defined by an independent cylindrical
wall releasably engageable with the cylindrical walls of the
adjoining cylinders so as to define the series of longitudinally
aligned cylinders, said tubular body including at least one
removable end cap thereon for the introduction of the sectionally
constructed rod and cylinders.
2. The tool of claim 1 wherein each of said rear chambers not
communicated with the second fluid passage means is substantially
airtight upon forward movement of the piston therein whereby a
vacuumlike condition is developed which provides an inherent
retracting force on the piston and hence the piston rod.
3. The tool of claim 2 including a one-way check valve in each of
said rear chambers not communicated with the second fluid passage
means providing for an exhausting of air in the corresponding rear
chamber upon a rearward movement of the corresponding piston.
4. The tool of claim 3 wherein one of said cylinders is integrally
formed with and interiorly within said tubular body.
5. The tool of claim 4 wherein the fluid passage means through the
piston rod comprises the first fluid passage means, and the fluid
passage means about the cylinders comprises the second fluid
passage means.
6. A force amplifying tool comprising a series of longitudinally
aligned cylinders, a piston operatively disposed in each cylinder,
an elongated piston rod extending slidably through said cylinders
and engaged with said pistons, one end of said rod being adapted to
mount a workhead, each piston defining forward and rear chambers in
the corresponding cylinder, first fluid passage means communicating
with all of the forward chambers, second fluid passage means
communicating with at least a major number of the rear chambers,
and an elongated tubular body enclosing said cylinders and fluid
passage means, said elongated piston rod being formed of a
plurality of releasably interconnected hollow rod sections, at
least the majority of said pistons being mounted between adjacent
rod sections, each cylinder being defined by an independent
cylindrical wall releasably engageable with the cylindrical walls
of the adjoining cylinders so as to define the series of
longitudinally aligned cylinders, said tubular body including at
least one removable end cap thereon for the introduction of the
sectionally constructed rod and cylinders.
7. A force amplifying tool comprising a series of longitudinally
aligned cylinders, a piston operatively disposed in each cylinder,
an elongated piston rod extending slidably through said cylinders
and engaged with said pistons, one end of said rod being adapted to
mount a workhead, each piston defining forward and rear chambers in
the corresponding cylinder, first fluid passage means communicating
with all of the forward chambers, second fluid passage means
communicating with at least a major number of the rear chambers,
and an elongated tubular body enclosing said cylinders and fluid
passage means, each of said rear chambers not communicated with the
second fluid passage means being substantially airtight upon
forward movement of the piston therein whereby a vacuumlike
condition is developed which provides an inherent retracting force
on the piston and hence the piston rod.
8. The tool of claim 1 wherein the fluid passage means through the
piston rod comprises the second fluid passage means, and the fluid
passage means about the cylinders comprises the first fluid passage
means.
9. The tool of claim 8 wherein each of said pistons is integrally
formed with one of said piston rod sections.
10. The tool of claim 9 including a one-piece elongated hollow
shaft extending through the piston rod sections, said shaft
defining an internal airflow passage and having lateral openings
therethrough communicating with the interior of said piston rod
sections, and means on the opposite ends of said shaft for
engagement with the endmost piston rod sections in a section
clamping manner.
11. The tool of claim 10 including an elongated air passage defined
through said body parallel to the cylinder receiving interior
thereof and communicated with the cylinder receiving interior
thereof via lateral openings.
12. A force amplifying tool comprising a series of longitudinally
aligned cylinders, a piston operatively disposed in each cylinder,
an elongated piston rod extending through said cylinders and
engaged with said pistons, each piston defining a forward and a
rearward chamber in the corresponding cylinder, first airflow means
communicated with all of the forward chambers, second airflow means
communicated with the rear chambers of a major number os said
cylinders, check valve means associated with the rear chambers not
communicated with the second airflow means for precluding an
introduction of air into said chambers upon a forward movement of
the associated pistons whereby a vacuumlike condition is developed
therein, and allowing an exhaust of these rear chambers upon a
rearward movement of the pistons therein, the pistons in the
cylinders having the noncommunicating rear chambers being fixed to
the piston rod for forward movement therewith induced by the
introduction of pressure through the airflow means communicating
with the rear chambers of those cylinders wherein the rear chambers
communicate with the second airflow means.
13. The tool of claim 12 wherein said first airflow means is
defined longitudinally through said piston rod.
14. The tool of claim 12 wherein said second airflow means is
defined substantially circumferentially about the cylinders having
the communicated rear chambers.
15. The tool of claim 12 including a pair of cooperating valve
units for controlling the flow of air through the first and second
airflow means, each valve unit including a pair of spaced valves
and spaced valve seats orientated relative to the valves so as to
provide for a seating of only one valve at a time, and spring means
biasing each valve unit to a predetermined position.
16. The tool of claim 7 including a one-way check valve in each of
said rear chambers not communicated with the second fluid passage
means providing for an exhausting of air in the corresponding rear
chamber upon a rearward movement of the corresponding piston.
17. The tool of claim 7 wherein one of said cylinders is integrally
formed with and interiorly within said tubular body, the remainder
of said cylinders being independent of said tubular body and
positioned generally concentrically therewith.
18. A force amplifying tool comprising a series of longitudinally
aligned cylinders, a piston operatively disposed in each cylinder,
an elongated piston rod extending slidably through said cylinders
and engaged with said pistons, one end of said rod being adapted to
mount a workhead, each piston defining forward and rear chambers in
the corresponding cylinder, first fluid passage means communicating
with all of the forward chambers, second fluid passage means
communicating with at least a major number of the rear chambers,
each of said rear chambers not communicated with the second fluid
passage means being substantially airtight upon forward movement of
the piston therein whereby a vacuumlike condition is developed
which provides an inherent retracting force on the piston and hence
the piston rod.
19. The tool of claim 18 including a one-way check valve in each of
said rear chambers not communicated with the second fluid passage
means providing for an exhausting of air in the corresponding rear
chamber upon a rearward movement of the corresponding piston.
20. A force amplifying tool comprising a series of longitudinally
aligned cylinders, a piston operatively disposed in each cylinder,
an elongated piston rod extending slidably through said cylinders
and engaged with said pistons, one end of said rod being adapted to
mount a workhead, each piston defining forward and rear chambers in
the corresponding cylinder, first fluid passage means communicating
with all of the forward chambers, second fluid passage means
communicating with at least a major number of the rear chambers,
and an elongated tubular body enclosing said cylinders and fluid
passage means, each cylinder being defined by a cylindrical wall
formed independently of the walls of the adjoining cylinders, said
cylindrical walls being releasably engageable with the cylindrical
walls of the adjoining cylinder so as to define the series of
longitudinally aligned cylinders, at least one of said cylindrical
walls being integrally formed with and interiorly within said
tubular body, said tubular body including at least one removable
end cap thereon for the introduction of the rod and cylinders.
21. The tool of claim 20 wherein each of said cylindrical walls
other than the cylindrical wall integrally formed with the tubular
body is formed independently of said tubular body and generally
concentrically positioned with regard thereto in alignment with the
integrally formed cylindrical wall.
Description
The instant invention is generally concerned with a pneumatic tool
wherein multiple pistons are mounted on a common piston rod and
operative within multiple cylinders, each communicated with a
common source of pressurized air for an amplification of the
resultant force.
It is a primary object of the instant invention to provide for a
unique arrangement of elements which enable the achievement of a
substantial force amplification in a small hand manipulatable tool,
the operative elements being located within a compact body devoid
of encumbering projections or the like.
Another significant object of the instant invention resides in the
provision of a power unit which is adaptable to a wide variety of
tools, including rivet pullers, staplers, nailers, and other types
of driving or pulling implements.
Furthermore, an important object of the instant invention resides
in the provision of a tool which is, while highly unique,
structurally simple and operationally dependable.
Basically, the tool of the instant invention is sectional in
construction, including a plurality of cylinders longitudinally
mounted within a slightly enlarged body whereby air passage means
is defined within the body about the cylinders. Each cylinder
receives a piston therein which, through a sectional piston rod, is
aligned and cooperates with the remaining pistons in providing for
an amplification of the force derived from the air pressure
supplied. An appropriate control valve system is utilized for
directing the intake of air so as to selectively advance and
retract the pistons, and an appropriate workhead is mounted on the
forward end of the rod and operates on the workpiece in response to
the extension and retraction of the piston rod.
These together with other objects and advantages which will become
subsequently apparent reside in the details of construction and
operation as more fully hereinafter described and claimed,
reference being had to the accompanying drawings forming a part
hereof, wherein like numerals refer to like parts throughout, and
in which:
FIG. 1 is a perspective view of a rivet pulling tool incorporating
the features of the instant invention;
FIG. 2 is a partial perspective view, with portions broken away and
exploded, of the tool body and handle;
FIG. 3 is an enlarged transverse cross-sectional view taken
substantially on a plane passing along line 3-3 of FIG. 1;
FIG. 4 illustrates the work to be performed by the particular tool
illustrated;
FIG. 5 is an exploded perspective view of the force amplifying
elements of the tool;
FIG. 6 is a rear elevational view of a modified tool;
FIG. 7 is a cross-sectional view of the modified tool taken
substantially on a plane passing along line 7-7 in FIG. 6;
FIG. 8 is an enlarged cross-sectional view taken substantially on a
plane passing along line 8-8 in FIG. 7;
FIG. 9 is an enlarged cross-sectional detail of several of the
components of the modified tool;
FIG. 10 is an exploded perspective view of the operating elements
of the modified tool; and
FIG. 11 is a further exploded perspective view of several of the
components .
Referring now more specifically to the drawings, reference numeral
20 is used to generally designate a tool incorporating the
advantages of the instant invention. The particular tool
illustrated is a rivet puller which operates in the manner
suggested in FIGS. 1 and 4, this basically involving an extension
of the chuck 22 into gripping engagement with a naillike rivet
expander 24 which, upon a retraction of the chuck 22, is drawn
rearwardly so as to expand the rivet 26 and subsequently broken,
leaving the rivet expanding head thereof locked within the rivet.
It will of course be appreciated that the operative components of
the tool, as shall be explained in detail subsequently, are equally
adapted to a variety of other types of handtools, however, the
utilization of the features of this invention in a rivet pulling
tool is considered particularly advantageous in view of the extreme
force needed to pull the rivets and the manner in which the
resultant tool can be of a compact easily handled size.
The tool 20, regardless of the particular workhead to be associated
therewith, includes an elongated hollow cylindrical body 28
including open internally threaded forward and rear end portions 30
and 32. In addition, the cylindrical body 28 includes, inwardly
offset from the forward end portion 30 thereof, an annular inwardly
offset smooth piston receiving portion or cylinder 34 presenting
forwardly and rearwardly directed annular shoulders 36 and 38.
A cylinder head 40, including an annular sealing ring 42
thereabout, is seated within the forward end of the integral
cylinder 34, this head 40 including an annular flange 44 thereabout
which seats on the forward cylinder forming shoulder 36. An
externally threaded forward end cap 46 is threaded within the
internally threaded forward end 30 of the body 28. The cap 46,
hollow so as to define a forward cylinder 48, extends a sufficient
distance into the forward end portion of the body 28 so as to
clampingly engage the cylinder head 40 into position against the
annular shoulder 36. Actually, the external threads on the cap 46
are provided on an intermediate portion thereof, terminating short
of the inner portion of the cap so as to provide for an annular air
space 50 about the inner end portion of the cap 46 between the cap
46 and the cylindrical body 28. In addition, the threaded portion
of the cap 46 terminates short of the outer end portion of the cap
which is slightly enlarged relative to the body received threaded
portion so as to seat against and provide for a smooth continuation
of the body. In order to communicate the interior of the cylinder
48 with the annular space 50, suitable airflow permitting notches
52 are provided at spaced points through the inner edge portion of
the cap 46.
A hollow rear end cap 54 includes an externally threaded forward
portion 56 which is threaded within the internally threaded rear
end portion 32 of the body 28 and defines a piston receiving
cylinder 58. A cylinder head 60 is sealingly received within the
internal forward end portion of the cylinder 58, the cylinder head
60 including an annular flange 62 thereabout which bears against
the extreme annular forward end of the cap 54 so as to properly
orientate the head 60.
A series of intermediate cylinders 64 are defined between the
integrally formed cylinder 34 and the rear cap cylinder 58 by a
series of cylindrical walls 66 of a slightly lesser diameter than
the interior of the cylindrical body 28 so as to define an air
space 68 about the cylinders 64 within the body 28 itself. The
intermediate cylinders 64, two appearing in the illustrated
embodiment of FIG. 3, are separated from each other by an
intermediate cylinder head 70 which is sealingly received within
the rear cylinder 64 and positioned therein by an appropriate
annular flange 72 seating against the annular forward edge of the
associated cylinder wall 66. The rear edge of the rearmost one of
the cylinder walls 66 seats against the positioning flange 62
associated with the cap formed cylinder 58. The forwardmost ones of
the cylinders 64 in turn sealingly receives a cylinder head 74
within the forward end portion thereof, the cylinder head 74
including an annular enlarged flange thereon which seats both
against the rear edge 38 of the integral cylinder 34 and the
annular forward edge of the forwardmost cylinder wall 66. It should
of course be appreciated that the cylindrical body 28 is of a
length whereby upon a mounting of the end caps 46 and 54, the
aforedescribed cylinder heads and internal cylinders shall assume a
reasonably snug relationship relative to each other as illustrated
in FIG. 3.
Both cylinders 64 as well as the cylinder 34 are to be communicated
with the encircling air space 68. As such, the rear end portions of
both cylinder forming walls 66 are provided with air passing
notches or openings 76 therein, providing for the communication
between the space 68 and the cylinders 64, and the cylinder head 74
is provided with peripherally spaced air passing notches 78 through
the positioning flange provided thereabout, thereby communicating
the space 68 with the cylinder 34.
A sliding piston 80 is slidably provided in each of the cylinders,
such pistons 80 being mounted on a common piston rod 82 which
extends longitudinally through the cylinder heads and forward cap
46, being appropriately sealed relative thereto by suitable O-ring
seals.
The piston rod 82 is essentially formed by a plurality of hollow
communicating releasably interconnected piston rod sections 84,
including a forwardmost section 84' and a rearmost section 84".
Each of these piston rod sections includes a reduced diameter rear
portion which defines an annular shoulder against which one of the
pistons 80 seats. The reduced diameter rear portion associated with
the rearmost piston rod section 84" is of a length corresponding
approximately to the thickness of the rearmost piston 80 and is
internally threaded for the reception of a mounting bolt 86 which
mounts the rearmost piston 80 thereon. The reduced diameter
rearmost portions of the remainder of the sections are externally
threaded and threadedly received within the internally threaded
forwardmost portions of the rod sections immediately rearward
thereof. Each of the rod sections 84 and 84" also includes an
outwardly directed annular flange 88 about the forward end thereof,
such flanges 88 defining seats for the pistons 80 located in the
chambers 48, 34 and 64. These pistons 80 are in turn firmly clamped
against the rod section flanges 88 by the shoulders defined by the
reduced rear end portions of the piston rod sections immediately
forward thereof. It is believed that this arrangement will be
readily apparent from a consideration of FIG. 3. With the piston
rod 82 so assembled, it will be noted that a continuous air passage
is formed therethrough from the rear mounting bolt 86 through the
rear portion of the forward rod section 84' to a point
corresponding approximately to the forward wall of the forwardmost
cylinder 48. This internal air passage, hereinafter designated by
reference numeral 90, is in turn communicated with each of the
cylinders by means of lateral air passages or openings 92, at least
one being provided immediately forward of each piston 80 and so
located as to remain in communication with the corresponding
chamber at the forwardmost limit of the travel of the corresponding
piston 80.
A control handle 94 is provided, normally integrally, on the
cylindrical body 28 and depends therefrom. This handle 94 includes
conventional means (not illustrated) for engagement with both inlet
and outlet air hoses for the supply and exhausting of air under
pressure. Such air lines will, when connected, communicate with an
air inlet passage 96 and an air exhaust passage 98. A pair of
cooperating valve units 100 and 102 are communicated between the
air passages 96 and 98, and air passages 104 and 106. The air
passage 104 communicates with the air space 68 surrounding the
cylinders 64, and the air passage 106 extends into the cylinder 34
forward of the piston 80 therein for communication with the central
air passage 90 through the piston rod 82. In order to provide for
an adequate flow of air between the piston rod passage 90 and the
airflow passage 106, a plurality of the lateral air openings 92 can
be provided circumferentially about the piston rod 82 within the
cylinder 34 forward of the associated piston 80. Further, it will
of course be appreciated that the air passage 106 is communicated
with the cylinder 34 at a point forward of the forwardmost position
assumed by the piston 80 in this particular cylinder. A pivotally
mounted trigger 108 is provided between and in engagement with the
two valve units 100 and 102 for a control thereof in selectively
directing the pressure to either the air passage 104 or the air
passage 106.
The valve unit 100 consists basically of a pair of valves 110 and
112 selectively engageable with a pair of opposed valve seats 114
and 116. A valve spacing pin 118 extends through a reduced passage
connecting the seats 114 and 116, the pin 118 orientating the
valves 110 and 112 relative to each other so as to provide for an
unseating of one of the valves upon a seating of the other valve. A
biasing spring 120 provided inward of the valve 112 normally biases
the valve 112 against its seat along with a corresponding movement
of the valve 110 away from its seat. A sliding plunger 122 projects
forwardly from engagement with the valve 110 into engagement with
the lower portion of the trigger 108 which is in turn, in its at
rest position, biased forwardly by a coiled biasing spring 124
encircling the plunger 122.
The valve unit 102 is of a construction generally similar to that
of the valve unit 100 in that it incorporates a pair of pin spaced
valves 126 and 128 orientated relative to each other in a manner
whereby upon the seating of one of the valves the other valve
unseats, this seating occurring to the opposite sides of a reduced
passage through which the spacing pin 130 projects. A biasing
spring 132 is located inward of an in engagement with the inner
valve 128, this spring, in the absence of an external force, being
sufficient to bias the valve 128 into engagement with its seat and
correspondingly bias the valve 126 away from its seat. However, the
main biasing spring 124 associated with the valve unit 100 is
productive of a biasing force sufficient so as to, through a
pivoting of the trigger 108 which engages against a plunger 134 in
the valve unit 102, compress the spring 132, unseating the valve
128 and seating the valve 126. Thus the at rest position of the
control apparatus is as illustrated in FIG. 3. In this position,
air entering through the air inlet passage 96 will travel through a
chamber behind the seated valve 112, through an air passage 136
into the chamber receiving the unseated valve 128, and from there
through a passage 138 communicated with the air passage 104 which
in turn directs the incoming air to the cylinder surrounding space
68. The air in the space 68 in turn passes into the three
intermediate cylinders 64 and 34, such being the only cylinders
communicated with the space 68. This introduction of pressurized
air into the three cylinders forces the pistons 80 therein, as well
as the attached piston rod, forwardly so as to extend the workhead
22. This forward movement of the piston rod 82 of course also
effects a forward movement of the two pistons 80 in the two end
cylinders 48 and 58, notwithstanding the lack of communication of
the cylinders with the incoming air. This forward movement of the
two end pistons results in the creation of a vacuum in the rear
chambers of the two end cylinders 48 and 58 which is considered
highly significant in substantially amplifying the return or
working stroke of the piston 82, acting somewhat in the manner of a
return spring, while at the same time eliminating such a spring and
the defects and structural limitations incident to the use of such
a spring. During this forward stroke, it will be appreciated that
the exhausting air will move through the hollow passage 90 within
the piston rod itself, exhausting through the passage 106 into a
diagonal passage 140 which bypasses the valve unit 102 and
communicates with the valve unit 100 in the reduced passage which
receives the valve spacing pin 118. The exhausting air then moves
by the unseated valve 110 and through the exhaust air line 98.
When a return stroke of the piston rod 82 is desired, the trigger
108 is pulled, seating the valves 110 and 128 and unseating the
valves 116 and 126. The air intake passage 96 is then communicated
with the air lines 140 and 106 for an introduction of the air into
the hollow passage 90 of the piston rod 82 for discharge into all
of the cylinders forward of the pistons 80 therein. At the same
time, the air exhaust line 98 is communicated with the air passage
104 and the cylinder surrounding air space 68 for an exhausting of
the air in the three intermediate cylinders. Upon a rearward or
retracting movement of the pistons 80 in the front and rear
cylinders 48 and 58, any air trapped therein will be allowed to
escape through appropriate one-way check valves 142 and 144, the
valve 142 communicating with the small air space 50 surrounding the
inner end of the cylinder 48 and communicated therewith by the
notches 52, and the check valve 144 communicated directly with the
interior of the cylinder 58 through the end cap 54 itself. The
presence of air to the rear of the front and rear pistons 80
associated with the front and rear cylinders 48 and 58, will
normally occur during periods of nonuse, notwithstanding the
practically sealed nature of these chambers which is utilized to
develop the return stroke amplifying vacuums. As such, in most
instances, as an initial step to using the tool after a period of
nonuse, prior to an engagement with the workpiece, the trigger will
be pulled so as to retract the rod 82 and pistons, expelling the
air from the forward and rear vacuum chambers. Thus, upon a release
of the trigger and a forward movement of the pistons, the desired
vacuum will be developed in conjunction with a gripping of the
workpiece by the appropriate workhead or chuck 22, after which the
trigger 108 can again be pulled so as to effect the powered return
stroke amplified by the two vacuum chambers. Incidently, one
additional advantage residing in the formation of the cylinders 64
by cylindrical walls or sleeves 66 is to make these cylinders in
fact floating cylinders capable of compensating for any slight
misalignment of the pistons or rod sections without affecting the
operation of the tool.
Insofar as the structure provided on the forward end of the tool of
FIG. 3 is concerned, such consists essentially of a chuck cover 146
mounting a hollow chuck opening abutment 148 for engagement by the
forwardly moving chuck so as to spread the jaws thereof for
gripping reception to the shank of a pin 24 or the like which can
be inserted through the abutment forming member 148.
Attention is now particularly directed to FIGS. 6--11 wherein a
modified tool 150 is illustrated. The tool 150, similar to the tool
20, also uses a multiple cylinder and piston arrangement operative
in conjunction with a common piston rod 152 extending
longitudinally therethrough.
Each of the cylinders 154 is defined by a cylindrical wall 156
having an integral cylinder head 158 on the forward end thereof.
The cylindrical wall 156 is inwardly offset peripherally about the
cylinder head 158, as indicated by reference numeral 160, and is
internally enlarged at the other end thereof, as indicated by
reference numeral 162. An internal abutment shoulder 164 is defined
by the internally enlarged end portion 162 with this abutment
shoulder seating against the slightly inwardly offset cylinder head
158 of a cylinder 154 immediately to the rear thereof, the length
of the internal offset portion 162 being slightly less than the
external offset portion 160 so as to provide in effect an annular
groove 166 about the joined cylinders which is in turn directly
communicated with the adjoining cylinder 154 by means of radial air
passages 168 provided through the inwardly offset end portion 160
immediately behind the cylinder head 158. It will also be noted
that an appropriate O-ring seal 170 is provided about the cylinder
head 158 so as to seal the open end portion 162 of the cylinder 154
which engages thereabout. With reference to FIG. 7, it will be
appreciated that the stacked cylinders 154 are positioned within a
slightly enlarged hollow bore 172 provided in the body 174 of the
tool 150. The forwardmost cylinder has a modified head 176 thereon
which is sealed against the closed forward end 178 of the bore 172
by means of an appropriate O-ring 180, while the last or rearmost
cylinder has a modified flat rear end portion 182 appropriately
sealed against a body end cap 184 releasably bolted on the body
subsequent to the introduction of the various operating
components.
The piston rod 152 includes an elongated hollow shaft 186 having an
enlarged head 188 on the rear end thereof slidably received
centrally through the end cap 184 and sealed relative thereto by an
appropriate O-ring seal 190. The shaft 186 is surrounded by a
plurality of slightly enlarged tubular piston rod sections 192,
each of which has a cylinder received piston 194 integral with the
rear end thereof. The rearmost piston 194 seats against an annular
shoulder defined by the enlarged head 188 on the shaft 186 with
each of the subsequent pistons 194 seating on an annular recessed
shoulder 196 provided on the leading end of the piston rod section
192 immediately therebehind. The pistons 194, as previously
indicated, are of course arranged one in each cylinder 154.
The forwardmost piston rod section 198 is modified as compared to
the remainder of the sections 192, the section 198 being
substantially longer and extending through the leading cylinder
head 176, the forward end of the body 174, and an externally
threaded mounting boss 200 on the body. The leading end of the rod
section 198 is provided with an appropriate internally threaded
bore 202 for the mounting of a chuck or working head 204, while the
trailing end of the rod section 198 is provided with an enlarged
internally threaded bore 206 for threaded engagement on the
externally threaded forward end of the shaft 186 in a manner so as
to clampingly mount all of the rod sections on the shaft 186. The
individual piston rod sections 192 are of course slidably received
through the cylinder heads 158 and appropriately sealed thereto by
O-ring seals 208.
Referring particularly to FIG. 8, it will be noted that the bore
172 through the tool body 174 is eccentrically located, providing
for a greater thickness of the body beneath the bore. An elongated
air passage 210 is provided longitudinally through this thickened
portion, commencing at the rear of the body 174 and terminating in
a laterally directed forward end portion 212 which communicates
with the bore 172 immediately adjacent and slightly forward of the
forwardmost cylinder head 176. In addition, in alignment with each
annular groove 166, defined between the adjacent cylinders 154, the
bore is provided with arcuate grooves 214 which are of a depth so
as to intersect the air passage 210 for a communication of the air
passage 210 with the bore 172 at these points. By the same token,
at these particular points, it will be appreciated that
communication will also be had with the interiors of the cylinders
154 immediately forward of the pistons 194 by means of the air
passing openings 168, the forward cylinder head 176 having similar
air passing openings 216 therethrough. Further, the bore 172 is
slightly larger than the annular cylinder walls 156 so as to
actually provide for a flow of air completely thereabout whereby
the interior of the bore 172 is used as an air passage, in addition
to providing for the accommodation of any slight misalignment
without affecting the operation of the unit. The initial manifold
type air passage 210 is itself communicated with an air passage 218
which, through an appropriate valve structure such as illustrated
in FIG. 3, will selectively be an air intake or exhaust.
A second air passage or air line 220 extends from the valve control
unit into communication with an annular air space 222 provided
about the forwardmost piston rod section 198, this air space being
directly communicated with the hollow interior 224 of the centrally
located shaft 186. This hollow interior is closed at the rear end
thereof by an appropriate plug 226 and is provided, at suitable
points along the length thereof, with lateral air passing openings
228 which provide for a discharge of air into the slightly enlarged
rod sections 192. Each of the rod sections, noting FIG. 9 in
particular, is itself provided with air passages 230 extending
generally laterally therefrom through the associated piston 194
into communication with the corresponding cylinder 154 to the rear
of the piston 194. Thus communication is made with each cylinder
154 to the opposite sides of the piston 194 therein, providing for,
through the control valve unit, a selective power driving of the
piston rod in opposed directions with the multiple piston and
cylinder arrangement providing for a substantial force
amplification, and with the structural arrangement of components,
including the air passage forming bore, providing for the
incorporation of the force amplification arrangement in a compact
handtool.
From the foregoing, it will be appreciated that a unique handtool
has been defined, such being in the nature of an air tool whereby a
multiple amplification of the force is achieved through the
utilization of a series of pistons and cylinders and a common
piston rod. The tool itself is, through the unique internal
construction thereof, highly compact and capable of being
constructed in a size corresponding to that of any conventional
power handtool, such as an electric drill or the like,
notwithstanding the substantial force amplification achieved. As an
example of the compactness of the tool, the overall length of the
tool in FIG. 1 need not be over 10 or 11 inches long to achieve
more than ample force for the purpose of pulling rivets, normally
an extremely difficult task. Further, at least in one embodiment of
the invention, it is contemplated that the force on the actual
working stroke be even further amplified through the provision for
a vacuum acting in the nature of a return spring.
The foregoing is considered as illustrative only of the principles
of the invention. Further, since numerous modifications and changes
will readily occur to those skilled in the art, it is not desired
to limit the invention to the exact construction and operation
shown and described, and accordingly all suitable modifications and
equivalents may be resorted to, falling within the scope of the
invention.
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