U.S. patent number 3,580,455 [Application Number 04/809,064] was granted by the patent office on 1971-05-25 for fastener driving device operating means.
This patent grant is currently assigned to Karl M. Reich Maschinenfabrik. Invention is credited to Adolf Cast, Heinz Schwarz.
United States Patent |
3,580,455 |
Cast , et al. |
May 25, 1971 |
**Please see images for:
( Certificate of Correction ) ** |
FASTENER DRIVING DEVICE OPERATING MEANS
Abstract
A powered fastener driving device having a power control means
for selectively supplying power to a driver blade which drives
fasteners out of the device, which power control means includes a
member movable between a first position where no power is supplied
to the driver blade and a second position where power is supplied
to cause the driver blade in the device to drive a fastener, said
control means including a counterreturn chamber therein which
prevents said movable member from returning from said second
position until after a predetermined lapse of time after the member
is moved to said second position from said first position, and a
crossmember pivotally mounted at its midpoint on said movable
member and arranged with a manually operated trigger and a slidable
workpiece touch-member which extends slightly beyond the front end
of the nose piece of the device to cause the movable member to said
second position when the trigger is pulled and the touch-member is
moved rearwardly by engaging said device nose piece to the
workpiece.
Inventors: |
Cast; Adolf (Oberlenningen,
DT), Schwarz; Heinz (Zizishausen, DT) |
Assignee: |
Karl M. Reich Maschinenfabrik
(Nurtingen, DT)
|
Family
ID: |
25200457 |
Appl.
No.: |
04/809,064 |
Filed: |
March 21, 1969 |
Current U.S.
Class: |
227/8;
227/130 |
Current CPC
Class: |
B25C
1/008 (20130101); B25C 1/043 (20130101) |
Current International
Class: |
B25C
1/04 (20060101); B25C 1/00 (20060101); B27f
007/14 () |
Field of
Search: |
;227/7,8,130 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Custer, Jr.; Granville Y.
Claims
We claim:
1. In combination with a fastener driving device having a main body
with a nose piece at its forward end, which nose piece has a
forward end and a barrel through which fasteners are sequentially
driven opening through said nose piece forward end, said device
having therein a driver blade assembly with a driver blade movable
between a rear position and a forward position where the driver
blade has driven any fastener out of the barrel:
power control means for selectively communicating power to said
driver blade assembly to drive it forward to said forward position,
said power control means including:
a movable member movable between a first position where said means
causes power to be held out of communication with said driver blade
assembly and a second position where said power control means
causes a communication of power to said driver blade assembly;
a crossmember having a first and a second point thereon, said
crossmember being pivotally connected to said movable member at a
third point on said crossmember, each of said first and second
points having an operative position, said movable member being in
said second position when both said first and second points are in
said operative positions and in said first position when less than
both of said first and second points are in said operative
positions;
trigger means having an engagement portion mounted on said body for
movement between an inoperative position where said engagement
portion does not force said second point on said cross member into
said second point operative position and an operative position
where said engagement portion engages and forces said second point
of said crossmember into said second point operative position;
and workpiece responsive means movably connected to said body for
forcing said first point of said crossmember into said first point
operative position when said front end of said nose piece is
brought into proximity with a workpiece, whereby said trigger means
may be held in said operative position and said device may be
operated by bringing said nose piece into proximity with a
workpiece.
2. The invention set forth in claim 1 wherein: said crossmember
first and second points are first and second ends of said
crossmember and said third point is a midpoint of said crossmember
between said first and second ends.
3. The invention set forth in claim 1 wherein said workpiece
responsive means includes: a workpiece touch-member slidably
mounted on said body for movement between a forward position where
a front end of said touch-member extends slightly beyond the front
end of said nose piece and a rear position where said touch-member
front end is substantially flush with the front end of said nose
piece, said touch-member having a rear end in line with said first
point on said crossmember, said touch-member rear end being capable
of transmitting to said crossmember first point force in only a
rearward direction, whereby said touch-member does not tend to
force the crossmember forward when the touch-member moves from its
rearward position to its forward position.
4. The invention set forth in claim 3 including:
return means connected to said touch-member for urging it to its
forward position at a very rapid rate;
means in said power control means for urging said movable member
from its second position toward its first position;
and means controlling the time needed to return said movable member
to said first position so that it takes longer for said movable
member to return from its second position to its first position
than it takes said return means to return said touch-member from
its rear position to its forward position.
5. The invention set forth in claim 1 including:
means operatively connected to said movable member for controlling
the time needed for said movable member to return from said second
position to said first position.
6. The invention set forth in claim 1 including:
means in said power control means for preventing said movable
member from moving back toward said first position until after the
lapse of a predetermined time after the movable member is moved to
said second position from said first position;
and means in said power control means for causing said movable
member to rapidly return to said first position after the lapse of
said predetermined time.
7. The invention set forth in claim 6 including:
means in said power control means for causing a large force to
rapidly accelerate said movable member toward said first position
during said movable member toward said first position during said
movement from said second position to said first position, said
last-mentioned means causing said forces on said movable member to
become substantially equal after the member has come to rest at
said first position except for a substantially smaller constant
force on the movable member urging said member toward said first
position.
8. In combination with a fastener driving device having a main body
with a nose piece at its forward end, which nose piece has a
forward end and a barrel through which fasteners are sequentially
driven opening through said nose piece forward end, said device
having therein a driver blade assembly with a driver blade movable
between a rear position and a forward position where it has driven
any fastener out of the barrel:
power control means for selectively communicating the power to said
driver blade assembly to drive it forward to said forward position,
said power control means including:
a movable member movable between a first position where said power
control means causes power to be held out of communication with
said driver blade assembly and a second position where said power
control means causes a communication of power to said driver blade
assembly;
means for selectively moving said movable member to said second
position;
and means operative to prevent said movable member from returning
from its second position to said first position until the lapse of
a predetermined time after the said member is moved from its first
position to its second position.
9. The invention set forth in claim 8 wherein said device has a
supply of pressurized fluid therein in communication with said
power control means, said pressurized fluid exerting a constant
force on said movable member when said member is in said second
position urging said member toward said first position and said
last-mentioned means includes:
a counterreturn chamber which is charged with said pressurized
fluid when said movable member is in said first position and
gradually loses fluid therefrom when said movable member is moved
to said second position, said pressurized fluid in said
counterreturn chamber urging said movable member toward said second
position, whereby said movable member will move toward said first
position when the pressure in the counterreturn chamber is reduced
sufficiently by loss of fluid therefrom.
10. The invention set forth in claim 9 wherein said power control
means includes:
a valve housing slidably receiving therein said movable member for
sliding movement between said first and second positions;
a first piston carried by said movable member and sealing with said
housing to form said counterreturn chamber on one side of the
piston;
an inlet pressure piston carried by said movable member, said inlet
pressure piston being in continuous communication with said supply
of pressurized fluid, the force of said pressurized fluid on said
inlet piston furnishing said constant force tending to urge said
movable member toward said first position, said inlet piston having
an operating face which is substantially smaller than the operating
face of said one side of said first piston;
and means for bleeding fluid out of said counterreturn chamber at a
predetermined rate when said movable member is in said second
position, whereby the fluid pressure in said counterreturn chamber
will hold the movable member in said second position until the
fluid pressure in said chamber is so low that the resultant force
thereof on said one side of said first piston becomes less than the
effective force of said constant fluid pressure on said operating
face of said inlet piston.
11. The invention set forth in claim 10 wherein:
said housing has a bore therethrough which receives therein said
inlet piston when said movable member is in said second position,
said inlet piston effectively sealing said bore and preventing
fluid from entering said housing until said member has moved a
predetermined distance from said second position toward said first
position;
and said first piston has a second side in said housing opposite
said one side disposed such that pressure thereon will urge said
movable member toward said first position, whereby after said
movable member has moved said predetermined distance from said
second position toward said first position fluid will enter the
housing and cause force on said second side of said first piston
which force will cause the movable member to rapidly return to said
first position.
12. In combination with a fastener driving device having a main
body with a pressurized fluid therein, said main body having a nose
piece at its forward end, which nose piece has a forward end and a
barrel through which fasteners are sequentially driven opening
through said nose piece forward end, said device having therein a
driver blade assembly with a driver blade and a piston movable by
fluid pressure on the rear side of said piston from a rear position
to forward position where the driver blade has driven any fastener
out of the barrel:
a main valve movable between a first position where the area on the
rear side of the piston of the driver blade assembly is vented to
atmosphere and a second position where said last-mentioned area
communicated with said pressurized fluid within the device, said
main valve having a first side and moving to said first position
when said first side is subject to said pressurized fluid within
said device and moving to said second position when said first side
is vented to atmosphere;
passage means communicating said pressurized fluid with said first
side of said main valve member;
power control means in said passage means for selectively
communicating said first side of said main valve member alternately
between said pressurized fluid and atmosphere, said power control
means comprising:
a movable member movable between a first position where said power
control means causes power to be held out of communication with
said driver blade assembly and a second position where said power
control means causes a communication of power to said driver blade
assembly;
means for selectively moving said movable member to said second
position;
and means operative to prevent said movable member from returning
from its second position to said first position until the lapse of
a predetermined time after said member is moved from said first
position to its second position.
13. The invention set forth in claim 12 wherein:
said device has a supply of pressurized fluid therein in
communication with said power means, said pressurized fluid
exerting a constant force on said movable member when said member
is in said second position urging said member toward said first
position, and said last-mentioned power control means includes:
a counterreturn chamber which is charged with said pressurized
fluid when said movable member is in said first position and
gradually loses fluid therefrom when said movable member is moved
to said second position, said pressurized fluid in said
counterreturn chamber urges said movable member toward said second
position, whereby said movable member will move toward said first
position when the pressure in said counterreturn chamber is reduced
sufficiently by loss of fluid therefrom.
14. The invention set forth in claim 13 wherein said power control
means includes:
a valve housing slidably receiving therein said movable member for
sliding movement between said first and second position;
a first piston carried by said movable member and sealing with said
housing to form said counterreturn chamber on one side of the
piston;
an inlet pressure piston carried by said movable member, said inlet
pressure piston being in continuous communication with said supply
of pressurized fluid, the force of said pressurized fluid on said
inlet piston furnishing said constant force tending to urge said
movable member toward said first position, said inlet piston having
an operating face which is substantially smaller than the operating
face of said one side of said first position;
and means for bleeding fluid out of said counterreturn chamber at a
predetermined rate when said movable member is in said second
position, whereby the fluid pressure in said counterreturn chamber
will hold the movable member in said second position until the
fluid pressure in said chamber is so low that the resultant force
thereof on said one side of said first piston becomes less than the
effective force of said constant fluid pressure on said operating
face of said inlet piston.
15. The invention set forth in claim 8 including:
a crossmember having a first and a second end thereon, said
crossmember being pivotally connected to said movable member at the
center of said crossmember, each of said first and second ends
having an operative position, said movable member being in said
second position when both said first and second ends are in said
operative positions and in said first position when less than both
of said first and second ends are in said operative positions;
trigger means having an engagement portion mounted on said body for
movement between an inoperative position where said engagement
portion does not force said second end of said crossmember into
said second end operative position and an operative position where
said engagement portion engages and forces said second end of said
crossmember into said second end operative position;
and workpiece responsive means movably connected to said body for
forcing said first end of said crossmember into said first end
operative position when said front end of said nose piece is
brought into proximity with a workpiece, whereby said trigger means
may be operated by bringing the nose piece into proximity with the
workpiece and the device will not erroneously recycle if said
workpiece responsive means is very rapidly brought into proximity
with a workpiece and then moved slightly away therefrom and then
brought back into proximity with the workpiece.
16. The invention set forth in claim 15 wherein said workpiece
responsive means includes:
a workpiece touch-member slidably mounted on said body for movement
between a forward position where a front end of said touch-member
extends slightly beyond the front end of said nose piece and a rear
position where said touch-member front end is substantially flush
with the front end of said nose piece, said touch-member having a
rear end in line with said first end of said crossmember, said
touch-member rear end being capable of transmitting to said
crossmember first end force in only a rearward direction, whereby
said touch-member does not tend to force the crossmember forward
when the touch-member moves from its rearward position to its
forward position.
17. The invention set forth in claim 9 including:
means in said last-mentioned means for charging said counterreturn
chamber with pressurized fluid at a more rapid rate than the rate
at which fluid is lost from said chamber.
18. The invention set forth in claim 9 wherein said last-mentioned
means comprises:
a piston connected to said movable member;
a housing having a bore therein forming a first cylinder of
predetermined diameter and a second cylinder of slightly larger
diameter in axial alignment, said housing being positioned so that
said piston is received in said first cylinder when said movable
member is in said second position and said piston is in said second
cylinder when said movable member is in said first position;
means cooperating with said piston for sealing with said first
cylinder when said piston is in said first cylinder when said
piston is in said second cylinder, whereby pressurized fluid may
pass around the piston when it is in said second cylinder but not
when it is in said first cylinder.
19. The invention set forth in claim 2 including:
means operatively connected to said movable member for controlling
the time needed for said movable member to return from said second
position to said first position.
20. The invention set forth in claim 3 including:
means operatively connected to said movable member for controlling
the time needed for said movable member to return from said second
position to said first position.
21. The invention set forth in claim 2 including:
means in said power control means for preventing said movable
member from moving back toward said first position until after the
lapse of a predetermined time after the movable member is moved to
said second position from said first position; and
means in said power control means for causing said movable member
to rapidly return to said first position after the lapse of said
predetermined time.
22. The invention set forth in claim 3 including:
means in said power control means for preventing said movable
member from moving back toward said first position until after the
lapse of a predetermined time after the movable member is moved to
said second position from said first position;
and means in said power control means for causing said movable
member to rapidly return to said first position after the lapse of
said predetermined time.
23. The invention set forth in claim 11 including:
a crossmember having a first and a second end thereon, said
crossmember being pivotally connected to said movable member at the
center of said crossmember, each of said first and second ends
having an operative position, said movable member being in said
second position when both said first and second ends are in said
operative positions and in said first position when less than both
of said first and second ends are in said operative positions;
trigger means having an engagement portion mounted on said body for
movement between an inoperative position where said engagement
portion does not force said second end of said crossmember into
said second end operative position and an operative position where
said engagement portion engages and forces said second end of said
crossmember into said second end operative position; and
workpiece responsive means movably connected to said body for
forcing said first end of said crossmember into said first end
operative position when said front end of said nose piece is
brought into proximity with a workpiece, whereby said trigger means
may be operated by bringing the nose piece into proximity with the
workpiece and the device will not erroneously recycle if said
workpiece responsive means is very rapidly brought into proximity
with a workpiece and then moved slightly away therefrom and then
brought back into proximity with the workpiece.
Description
This invention relates to fastener driving device operating means
and more particularly to such means which will prevent a fastener
driving device from erroneously double acting.
A principal use of the present invention is in fastener driving
devices having operating means which include a manually
positionable trigger and a workpiece touch-member. In such devices,
the workpiece touch-member is slidably mounted on the device and
projects slightly beyond the nose piece of the device. The device
also includes a manually positionable trigger which cooperates with
the means for controlling the power to drive the driver blade such
that--when the trigger is moved to its operative position--the
device is actuated by moving the workpiece touch-member rearwardly
by touching the front end of the nose piece of the device to the
workpiece. Such devices have been provided in the past, however,
the following problem has been present. The operator will press the
fastener driving device against the workpiece and the recoil of
driving the fastener will "kick" the device slightly away from the
workpiece. This recoil is sufficient that the workpiece
touch-member will return to its original position. Then, the
continued pressure of the operator will cause the driving device to
move back against the workpiece and recycle at the same spot on the
workpiece.
Such double action, or recycling of the fastener driving device has
the disadvantage that two fasteners are placed where it is only
desired to place one fastener. In pneumatically powered fastener
driving devices, there is the additional problem that there may not
be sufficient power to drive the second fastener all the way into
the workpiece.
One aspect of the present invention is that it includes an
arrangement wherein the workpiece touch-member can only operate in
one way on the means which controls the power to the driver blade.
More particularly, the touch-member can only operate to cause to be
actuated the means controlling the power to the driver blade,
however, the touch-member cannot exert any force tending to return
the power control means to its unactuated condition.
Another aspect of the present invention is that the power control
means includes means which prevents the power control means from
recycling for a predetermined lapse of time after the power control
means is actuated. The operation of this aspect of the power
control means is further augmented by another aspect of the present
invention which provides that the trigger and the touch-member are
not physically connected to the power control means such that they
cannot reduce or effect the above mentioned lapse of time.
A further aspect of the present invention is that the power control
means includes structure which will cause the means to tend to snap
from one position to the other. This causes the device to operate
in a more regular fashion. This last mentioned aspect of the
present invention is augmented by an aspect of the present
invention which provides for large forces to cause the power
control means to return to its unactuated position, and yet those
forces will effectively diminish before the time that it is desired
to recycle the device.
With the foregoing in mind it is a major object of this invention
to provide an improved fastener driving device operating means.
Another object of this invention is to provide a fastener driving
device operating means which can be selectively operated through
the use of a workpiece touch-member.
A further object of this invention is to provide a fastener driving
device operating means which automatically prevents undesired
recycling of the driving device.
It is still another object of this invention to provide a fastener
driving device operating means which can be manufactured at a low
cost and operated with low maintenance.
Still another object of this invention is to provide fastener
driving device operating means which will prevent recycling of the
device for a predetermined time and then will rapidly reset said
means for a new operation.
Other and further objects of this invention will become apparent in
the detailed description below in conjunction with the attached
drawings wherein:
FIG. 1 is a partially cutaway side view of a fastener driving
device incorporating a preferred form of the present invention;
FIG. 2 is a fragmentary view of the nose piece portion of the
fastener driving device shown in FIG. 1 as seen from the left in
FIG. 1;
FIG. 3 is a fragmentary cross-sectional view disclosing the
arrangement of the power control means when trigger means is in the
actuated position and the workpiece touch-member is still in the
forward position;
FIG. 4 is a fragmentary cross-sectional view of the power control
means shown in FIG. 3 but with the workpiece touch-member in the
rearward position assumed when the fastener driving device is
brought into contact with the workpiece;
FIG. 5 is a fragmentary cross-sectional view of the power control
means shown in FIG. 3 with the workpiece touch-member returned to
its original position but before the movable member in the control
means has returned to its first position;
FIG. 6 is an enlarged fragmentary cross-sectional view of the first
preferred power control means with the movable member thereof in
the first position wherein the driving device driver blade would
not be actuated;
FIG. 7 is an enlarged fragmentary cross-sectional view of the power
control means shown in FIG. 6, but with the movable member therein
in the second position where the driver blade of the fastener
driving device would be actuated;
FIG. 8 is an enlarged fragmentary cross-sectional view of a second
preferred power control means the movable member thereof in the
first position wherein the driving device driver blade would not be
actuated;
FIG. 9 is an enlarged fragmentary cross-sectional view of the power
means shown in FIG. 8, but with the movable member therein in the
second position where the driver blade of the fastener driving
device would be actuated;
FIG. 10 is a cross-sectional view of the power control means shown
in FIG. 8 taken along line 10-10 in FIG. 8; and,
FIG. 11 is an enlarged fragmentary cross-sectional view of a
portion of the power control means taken along line 11 in FIG.
8.
Fastener driving devices of the type to be described are used in
many positions, e.g., when nailing horizontal floors, or when
nailing vertical walls. Therefore, although the invention is shown
in the relation disclosed in the drawings, i.e., with the driving
device pointed down, the invention will not generally be described
in that frame of reference. Rather, the invention will be described
on the basis that the nose piece of the driving device is at the
forward end of the device as the fasteners are driven out of the
forward end of the device. Therefore, generally speaking, the terms
"forward" and "rearward" will be used herein to establish a frame
of reference to relate the various components together.
In FIG. 1 there is disclosed a preferred embodiment of the present
invention incorporated in a pneumatically powered fastener driving
device. The particular fastener driving device disclosed is that
driver device disclosed in detail in U.S. Pat. No. 3,351,257.
Accordingly, reference is made to said patent for any disclosure of
the fastener driving device not specifically illustrated or
described herein.
In said FIG. 1, it can be seen that the fastener driving device has
a main body 10 which includes an air chamber cap 11 and a hollow
handle 12. At the front end of the main body 10 there is provided a
nose piece 15. A magazine 16 is secured to the nose piece 15 and to
the handle 12, which magazine has a stick, or strip, of nails 17
therein which are urged toward a barrel (not shown) in the nose
piece 15 by a spring driven follower 18. As the particular driving
device shown is operated by air pressure, there is an air hose
fitting 20 provided in order to communicate air pressure into air
chamber 21 in the handle 12 and the air chamber in the cap 11.
Indicated generally by the arrow 22, there is provided a power
control means which communicates the air in the chamber 21 with
passage 23. This passage 23 communicates with one side of a
cylindrical slide valve 24 which is the main valve of the driving
device. Further details of the driving device are shown in the
above mentioned patent. For the purposes herein, it is sufficient
to state that, when the main valve is in the position shown in the
FIGS. 1 and 3, the area on the rear side of the piston of the
driver blade assembly will be vented to atmosphere. When the main
valve 24 is in the position shown in FIGS. 4 and 5, the supply of
pressurized air in the chamber 21 and the cap 11 will be supplied
to the rear side of the piston of said driver blade assembly. In
this latter case, the driver blade assembly will be driven forward
to drive any fastener in the barrel of the nose piece 15 into a
workpiece.
The power control means 22 has a movable member 27 therein. When
the movable member 27 is in its first, or unactuated, position (the
lower position as shown in FIGS. 1 and 3) air pressure is
communicated from the chamber 21 through the passage 23 to the one
side of the main valve 24. When the movable member 27 is in its
second, or actuated, position (the upper position as shown in FIGS.
4 and 5) the passageway 23 is vented to atmosphere by structure to
be described. Before going on to the details in which this is
accomplished, the manner in which the movable member 27 is moved
between its first and second positions will now be described.
At its outer, or forward, end the movable member 27 has a clevis 28
secured thereto by means such as a pin. This clevis 28 has a cross
arm 29 pivotally mounted thereto through the use of a pin 30.
Preferably, the cross arm is pivotally mounted at its midpoint
thereof with first end 31 of the cross arm 29 located adjacent the
main body 10 while second end 32 of the cross arm is located away
from said main body.
Swingably secured to said body there is provided a trigger 35
having an engagement portion 36 thereon for a purpose to be
described. The trigger 35 is bifurcated at its left end (as seen in
FIGS. 1, 3, 4, and 5) in order to be swingably secured to the
device through the use of a pin 37. The trigger 35 can be moved
between its inoperative position shown in FIG. 1 and its operative
position shown in FIGS. 3--5. An adjustable stop 38 is provided in
order to adjust the operative position of the trigger 35.
A workpiece touch-member 40 is slidably mounted to the device by
means such as guide plates 41 which are secured to the nose piece
15. These guide plates 41 combine with bolts 42 to hold the
touch-member 40 in its desired position. As can be seen, the
touch-member 40 has a U-shaped front end 43 with a U-shaped front
edge 44. This touch-member 40 can be moved between its forward
position shown in FIG. 1 and a rear position where the front edge
44 is substantially flush with the front end of the nose piece 15
by pressing the device against workpiece 45.
Just above the guide plates 41, the touch-member 40 has a step
section 48 in order to get the touch-member to the side of the nose
piece 15. At said step portion 48, there is provided an upstanding
stub post 49 which is used to index compression spring 50. This
compression spring resiliently biases the touch-member 40 toward
its forward position. As shown in dashed lines in FIG. 1, the
touch-member 40 has an offset section 51 in order that the
touch-member may extend around the main body 10. From the offset
section 51, rear section 52 extends rearwardly (upwardly as seen in
FIG. 1) toward the power control means 22. The rear section 52 has
a rear plate 53 with a rear edge 54 thereon. As can be seen, the
rear edge 54 is directly in line with the first end 31 of the
crossmember 29.
Referring now to FIGS. 6 and 7, the details of the power control
means 22 will be described. The handle 12 has a bore 56 on the
forward side thereof which receives a generally cylindrical valve
housing body 57 with valve housing cap 58 threaded therein. O-rings
59 function to seal the exterior of the valve housing resulting
from the combination of the body 57 and the cap 58. Pin 60
functions to hold the body 57 and cap 58 in the bore 56.
Within the valve housing provided by the body 57 and the cap 58,
there is provided a cross plate 61 (which can be made as an
integral part of the valve housing cap as shown). This cross plate
61 has a plurality of air passages 62 therethrough concentrically
disposed around axial bore 63 which slidably receives therethrough
the movable member 27. O-ring 64 is provided to seal between the
cross plate 61 and the movable member 27, and counterbore 65 is
provided in the cross plate for a purpose which will be
described.
The structure of the cap 58 is further defined by an axial bore 66
which communicates the interior of the cap with the chamber 21.
Through front end 68 of the valve housing body 57 there is provided
an axial bore 69 through which the movable member 27 is received.
O-ring 70 functions to seal the area.
It will be noted that there is an enlargement 71 near the
midsection of the movable member 27. This enlargement 71 has a
forwardly facing annular forward edge 72 at its forward end. At the
rear end of the enlargement 71, there is provided a first piston 73
which is preferably secured to the movable member 27 by frictional
engagement. This piston 73 is sealed to the wall of the valve body
57 by means of O-ring 74. Thereby, a counterreturn chamber 75 is
provided on one side of the piston 73 between said piston and the
front end 68 of the valve housing body 57.
The manner in which the counterreturn chamber 75 operates will be
described further below. As will be described, it is necessary that
air pressure within the chamber 75 be allowed to bleed out of the
same. To this end, there are provided two bleed passages 76 in the
first piston 73, the size of which passages is determined by the
size of the counterreturn chamber 75 and the length of time it is
desired to prevent recycling. Thereby, air within the chamber 75
can communicate with chamber, or space, 77 on the opposite side of
the piston 73.
The movable member 27 is cylindrical with the centrally disposed
exhaust vent passage 78 extending the length thereof. Through a
pair of lateral vent ports 79, the vent passage 78 may communicate
at selected times with the interior of the valve housing cap 58.
Frictionally secured to the rear end of the movable member 27 (the
upper end as seen in FIGS. 6 and 7), there is secured a cap 80
which functions as an inlet piston having an operating face 81 with
a cylindrical skirt 82. It will be noted that the cap 80 has a
rearwardly tapered inner surface 83.
The apparatus works in the following manner. When the fastening
device is at rest, the compression spring 50 will bias the
touch-member 40 to the forward position shown in FIGS. 1 and 2.
When air pressure is supplied through the fitting 20 into the
chamber 21, said air pressure will move the movable member 27 to
the forward position shown in FIGS. 1, 2, and 6. The air pressure
would initially operate on the operating face 81, and then the rear
side of the first piston 73 (the upper side as shown in FIG. 6)
biasing the movable member 27 forwardly (downwardly as shown in
FIGS. 6 and 7). Even after the air pressure bleeds through the
passages 76 so that the air pressure is the same on both sides of
the piston 73, there would still be a net resultant force forcing
the movable member 27 toward the forward position--which force is
equal to the product of the air supply pressure times the
cross-sectional area of the bore 69.
When the operator does not have the trigger 35 pulled to its
operative position against the stop 38, the driving device will not
actuate should the touch-member 40 be accidentally moved to its
rearward position. As best seen in FIG. 1, the crossmember 29 would
merely pivot about the pin 30. However, such would not be the case
if the trigger 35 were moved to its operative position.
In FIG. 3, there is shown the device with the trigger 35 moved to
its operative position resting against the stop 38. In this
position, the movable member 27 is still in its first, or forward,
position with the first end 31 of the crossmember 29 resting
against the rear edge 54 of the touch-member 40 and the second end
32 lightly engaging the engagement portion 36 of the trigger 35.
Substantially all of the force of the air pressure on the movable
member 27 is transferred directly from the edge 72 to the front end
68 of the valve housing.
At this time, the power control means 22 is in the relationship
shown in FIG. 6. As can be seen, air pressure in the chamber 21 may
communicate to the main valve 24 through the inlet bore 66, the
passages 62, and the passage 23. As explained in the above
mentioned patent, this will cause the valve member to move to its
rearward position (the upper position as shown in FIG. 3) which
causes the area on the rear side of the driver blade assembly will
be in its rearward position. Upon said connection of the air
pressure, and said movable member 27 moving into the position shown
in FIG. 6, air will bleed through the bleed passages 76 to cause
the counterreturn chamber 75 to be charged with the supply
pressure.
In operation, the operator will merely move the trigger 35 to the
operative position. Then, he will go along sequentially hitting the
front end of the nose piece 15 of the fastener driving device
against the workpiece at the various positions that it is desired
to insert a fastener. This will move the touch-member 40 to its
rearward position causing the driving apparatus to operate as
follows.
Referring to FIG. 4, it can be seen that rearward movement of the
touch-member 40 will cause the upper edge 54 of the touch-member to
move the first end 31 of the crossmember 29 rearwardly (upwardly as
shown in FIG. 4). Since the engagement portion 36 of the trigger 35
prevents the second end 32 of the crossmember 29 from moving
forward, the movable member 27 is caused to be moved rearwardly to
the position shown in FIG. 4. When the movable member 27 is in the
position shown in FIG. 4, the power control means 22 is in the
relation shown in FIG. 7. At that time, air in the passage 23 can
be vented through the passages 62, and thence through the lateral
ports 79, and out through exhaust vent passage 78--causing the area
on the forward side of the main valve 24 to reduce to atmosphere.
As explained in the above mentioned patent, this will cause the
main valve 24 to move to the forward position--causing the driver
blade to be driven forward for the driving operation.
When the touch-member 40 causes the movable member 27 to move to
the second, or rearward, position, the inlet piston 80 will move
into and substantially seal off the inlet bore 66 (see FIG. 7 in
particular). Additionally, the seal between the front edge of the
skirt 82 and the O-ring 64 will be eliminated and air in the
passage 23 is very rapidly vented through the passages 62, and
thence through the lateral ports 79 and the exhaust vent passage
78. At the instant of this venting, there is set up an imbalance of
air pressure forces on said movable member. More particularly, the
counterreturn chamber 75 is still very nearly at the supply
pressure (the pressure having been reduced only by the enlargement
of the counterreturn chamber as the movable member is moved from
the position shown in FIG. 6 to the position shown in FIG. 7). And,
the effective face on the one side of the first piston 73 facing
the chamber 75 is sufficiently larger than the area of the
operating face 81 on the inlet piston 80 that the movable member 27
will remain in the position shown in FIG. 7 even if the
touch-member 40 were returned to its original forward position.
Therefore, in FIG. 5, the power control means 22 is illustrated
with the movable member 27 remaining in its rearward position even
though the touch-member 40 has returned to its forward
position.
As can be seen, the main valve 24 remains in its actuated position.
Therefore, if the touch-member 40 were immediately returned back to
its rearward position, the driving device would not be
recycled.
As the movable member 27 remains in the position in FIG. 7, the air
in the counterreturn chamber 75 will be slowly bled through the
bleed passages 76, relatively slowly (as compared to the speed at
which the air is vented from the passage 23) venting the air from
said counterreturn chamber. At some point, the pressure in the
counterreturn chamber 75 will become sufficiently less than the
supply pressure that the resultant force of the higher supply
pressure over the smaller operating face 81 of the inlet piston 80
overcomes the resultant force of the pressure in the counterreturn
chamber 75 over the larger area on the forward side of the piston
73. This will cause the movable member 27 to move forwardly until
the operating face 81 of the inlet piston clears the forward edge
of the bore 66. At that time, supply pressure will rush through the
passages 62 and charge the chamber, or space, 77 with supply
pressure, and will--through the passage 23--charge the forward side
of the main valve member 24 to move it back to its original
position shown in FIG. 1, 3, and 4.
It should be particularly noted how the structure gives a snap
action to the return of the movable member 27. More particularly,
when the supply pressure is supplied to the chamber, or space, 77
the supply pressure is not only operating on the operating face 81
but on the rear side of the first piston 73. Opposing this force
which urges the movable member 27 forward toward its first position
is only the rather low pressure (by this time) in the counterreturn
chamber 75. This is because the bleed passages 76 prevent the
chamber 75 from being charged as fast as the chamber, or space, 77.
Very shortly after the movable member 27 is returned to its first
position, the air will bleed through the passages 76 and return the
counterreturn chamber to the supply pressure. At this time, the
only imbalance of forces urging the movable member 27 toward its
first position would be the resultant force of the supply pressure
over the smaller operating face 81 of the inlet piston 80 (the
pressure is on both sides of the piston 73 being the same). This
smaller force can be easily overcome in the normal operation of the
fastener driving device as above described.
It will also be noted that the skirt 82 of the piston 80 is
received into the counterbore 65 before the operating face 81
clears the forward edge of the bore 66. This will substantially
eliminate losses of supply air through the ports 79 and exhaust
vent passage 78 during the time between when the operating face 81
clears the bore 66 and the front edge of the skirt 82 engages the
O-ring 64.
As mentioned previously, the size of the bleed passages 76 is
selected in order to accomplish the desired amount of delay between
the time the movable member 27 is moved from its first position
(shown in FIG. 6) to its second position (shown in FIG. 7).
Preferably, the bleed passages are sized so that there is
approximately 0.01 second delay before the return. A shorter or
longer delay may be accomplished by providing that the bleed
passages 76 are larger or smaller, respectively.
Referring now to FIGS. 8 to 11, a second preferred embodiment of
the power control means will be shown and described. In said FIGS.,
there is shown a power control means, indicated generally by the
arrow 99, received within the bore 56.
The power control means 99 includes a housing 100 which is sealed
to the bore 56 by means of O-rings 101, which housing has a bore
102 therein which receives a movable member 103 for movement
between a first position shown in FIG. 8 and a second position
shown in FIG. 8 and a second position shown in FIG. 9. A pin 104
holds the housing 100 in the bore 56 in the same manner as the pin
60.
At its rear end (the upper end as seen in FIGS. 8 and 9) the
housing bore 102 has been enlarged to provide an annular ledge 105
which functions to receive and hold a counterreturn chamber body
106 therein. A cap 107 is held by the pin 766 to the rear end of
the housing 100 and an O-ring 108 serves to seal the joinder
between the cap and the body 106.
The counterreturn chamber body 106 has a first cylinder 109 at its
rear end (the upper end as seen in FIGS. 8 and 9) with a second
larger cylinder 110 therein joined by a rearwardly tapering surface
111 for a function to be described. The body 106 is further defined
by a forwardly projecting portion 113 having an insert of Teflon or
nylon to form a suitable annular recess to receive an O-ring
115.
By means of ports 116 supply air from the chamber 21 is
continuously communicated with the bore 102 of the housing 100. The
housing 100 is further defined at its midportion by an annular
recess 117 which is in communication with the passage 23, and
communicates with the bore 102 through ports 118. Near its forward
end, the housing 100 has an O-ring 119 received in an internal
annular recess 120, which O-ring operates in a manner to be
described. The housing 100 is further defined by an exhaust port
122 adjacent front end 123 of the housing. A bore 124 in said front
end 123 slidably receives the front end of movable member 103 and
assists in guiding said front end of the movable member.
The movable member 103 has an enlargement 130 provided with a
centrally disposed recess to receive an O-ring 131 and with a
forwardly facing annular edge 133 (at the front end of the
enlargement). In engagement with the annular edge 133, there is
provided an O-ring 134 which has a normal diameter slightly smaller
than the diameter of the movable member. When the movable member
103 moves to its first position, this O-ring 103 is engaged by
front end 123 and cushions the stopping of the movable member.
Rearward of the enlargement 130, the movable member 103 is provided
with a cylindrical portion 135 which is slidably received in
sealing relation with the O-ring 115 of the counterreturn chamber
body 106. Further, at its rear end 136 (the upper end as seen in
FIGS. 8 and 9), the movable member 103 has a piston 137 secured by
means such as a shrink fit. The piston 137 carries an O-ring 138,
and serves to define a counterreturn chamber 140 in the area in
front of the piston (below the piston as seen in FIGS. 8 and 9).
(The manner in which the O-ring 138 cooperates with the walls of
the cylinders 109 and 110 and the tapered surface 111 is described
below.)
A pair of bleed passages 142 extend between front face 143 and rear
face 144 of the piston 137, and function in the same manner as the
bleed passages 76 in the first described embodiment. That is, they
function to allow the counterreturn chamber 140 to prevent return
of the movable member 103 to its first position for a predetermined
time after the movable member is moved to its second position.
As in the first embodiment, air must be supplied to the
counterreturn chamber 140. To this end, there is provided an axial
passage 146 extending from the rear end 136 of the movable member
103 to the midportion of the movable member where the axial passage
communicates with the exterior of the movable member through a
plurality of ports 147. As can be seen, the ports 147 extend
through the enlargement 130 at a position just below (as seen in
FIGS. 8 and 9) rearwardly facing tapered sealing surface 148.
Tapered sealing surface 148 functions in a manner which will be
described below.
Encircling the movable member 103, there is provided a cylindrical
inlet piston 150 of, e.g., nylon or Delrin which is slidably sealed
to the bore 102 by means of O-ring 151. The inlet piston 150 has an
operating face 153 on its rear side and as will be described
further below, said operating face functions the same as the
operating face 81 in the first embodiment. At its forward end, the
piston 150 has a skirt portion 154 which terminates in a forwardly
tapering outer surface 155. As can be seen in FIG. 8, the forwardly
tapering surface 155 engages and seals with the O-ring 119 when the
movable member 103 is in its first position.
The piston 150 has a first internal bore 156 which is received
around the enlargement 130 and seals with the O-ring 131 at all
times when the inlet piston is moved between its first position
relative to the movable member 103 (shown in FIG. 8) and its second
position relative to the movable member (shown in FIG. 9). At its
rear end, the inlet piston 150 has a second bore 157 which is
somewhat smaller than the bore 156. However, as the movable member
103 is smaller in this area of the bore 157, there is provided an
annular passage 158 which is able to be communicated selectively
with ports 159 in the inlet piston.
At the forward end of the bore 157, there is provided an annular
sealing surface 160. The tapered sealing surface 160 cooperates
with the tapered sealing surface 148 to prevent the passage of air
from the passage 158 to the ports 159 (and thence to either the
passage 23 or the exhaust port 122) in the manner to be described
below.
At the forward end of the movable member 103, there is located a
clevis 161. This clevis functions the same as the clevis 28, i.e.,
it receives the crossmember 29 (not shown) by means of a cross pin
(not shown). In this case, clevis 161 is secured to the forward end
of the movable member 103 by means of a U-shaped pin 162 which is
received in annular recess 163 on the movable member.
The operation of the power control means 99 is as follows. When the
control means 99 is in the position shown in FIG. 8, air is
supplied from the chamber 21, through the ports 116 and thence
through the passage 158 and the ports 159 to the passage 23. This
causes the driver blade of the fastener driving device to remain in
the rear position as in the first preferred power control means
22.
In this condition, air is supplied through the ports 147 and the
passage 146 to the area on the rear face 144 of the piston 137.
From the area on the rear side of the piston 137, supply pressure
air communicates with and charges the counterreturn chamber 140
through the bleed passages 142, and around the outer edge of the
piston. (It will be noted that the O-ring 138 is not in sealing
relation with the cylinder 110 when the movable member 103 is in
its first position.)
Before going on with the description of the manner of operation of
the power control means 99, it should be noted (see FIG. 8 in
particular) that rearward movement of the movable member 103 causes
the O-ring 138 to engage and seal with the cylinder 109 slightly
before the annular sealing surface 148 engages the annular sealing
surface 160. That is, the distance that the O-ring 138 must be
moved (from the position shown in FIG. 8) in order to seal with the
cylinder 109 is slightly less than the distance that the annular
sealing surface 148 must be moved (from the position shown in FIG.
8) in order to engage the annular sealing surface 160. Accordingly,
the counterreturn chamber 140 is sealed before control air is
vented from the control means 99 in the manner to be described.
As the movable member is moved rearwardly, it will move to an
intermediate position where the O-ring 138 seals with the cylinder
109 as just described. Then, slightly further rearward movement of
the movable member 103 will move said member to an intermediate
position where the tapered sealing surface 148 of the movable
member engages the tapered sealing surface 160 of the inlet piston
150. Further rearward movement of the movable member 103 will cause
the inlet piston 150 to move with the movable member. This action
causes the forwardly tapered surface 155 of the inlet piston 150 to
move away from the O-ring 119. At that time, air which is in the
passage 23 (and therefore operating on the main valve 24) is
exhausted through the recess 117, ports 118, bore 102, and exhaust
port 122. This will cause the driving device to be actuated as in
the first described embodiment. At this same time, air on the rear
face 144 of the piston 137 is vented through the passage 146 and
the ports 147. In FIG. 9, arrows 164 illustrate this venting
action. It will be noted that the sealing relation between the
surfaces 148 and 160 prevent supply air from replacing the vented
air.
Although the air on the rear face 144 of the piston 137 is very
rapidly vented, the air in the counterreturn chamber is not vented
as rapidly--because of the restrictive nature of the bleed passages
142. Therefore, air in the counterreturn chamber 140 assists in the
further movement of the movable member 103 to its second position
(as is the first embodiment). While the movable member 103 is in
its second position, air continues to bleed out of the chamber 140
through the bleed passages 142 causing the pressure in the chamber
140 to diminish. If the rearward force is removed from the movable
member 103, the pressure in the chamber 140 will maintain the
movable member 103 in its second position--as in the first
embodiment.
It will be noted in FIG. 9 that--at all times that the tapered
sealing surfaces 148 and 160 are in sealing position--there is a
constant force of supply pressure urging the movable member 103
towards its first position. This is the force of the air on the
operating face 153 plus the exposed area of the tapered surface 148
indicated by brace 165 in FIG. 9. The area indicated by the brace
165 is the annular area between the diameter of cylindrical portion
135 of the movable member 103 and the diameter of bore 157.
However, it will be noted that the operating face of the forward
face 143 of the piston 137 is substantially larger than the
combined areas of the operating face 153 of the inlet piston 150
and the area indicated by the brace 165. Therefore, the movable
member 103 is retained in its rearward position (and therefore, the
driver device will remain actuated) until such time as the air has
bled out of the counterreturn chamber 140 to a point where the
rearward force of that pressure in the counterreturn chamber
becomes less than the forward force on the operating face 153 and
the area indicated by the brace 165. At such time, the movable
member 103 will proceed to move forward.
As the movable member 103 moves forward, the tapered sealing
surfaces 148 and 160 remain in their sealing position until the
forwardly tapered surface 155 firmly engages the O-ring 119.
Slightly further forward movement will open the seal between the
surfaces 148 and 160. At this instant, supply air charges the
passage 23 to return the main valve 24 to its unactuated position.
Further, supply air passes through the ports 147 and the passage
146 to the area on the rear side of the piston 137.
This supply pressure on the face 144 of the piston 137 serves to
accelerate the movable member 103 forward since the supply pressure
is greater than the pressure in the counterreturn chamber 140.
However, the imbalance of pressure is only for a brief instant
since the continuing movement of the movable 103 moves the O-ring
138 to a position where it no longer seals with the cylinder 109.
Once that seal of the O-ring 138 is broken, the counterreturn
chamber 140 is very rapidly recharged with supply pressure.
It can be seen that the power control means 99 has certain
advantages over the power control means 22. Primarily, the power
control means 99 is able to recharge the counterreturn chamber 140
by air passing around the piston 137 rather than through the bleed
passages 142. Therefore, the bleed passages 142 can be sized
smaller in order to cause a longer delay before the movable member
103 returns to its first position without requiring a corresponding
delay in the time necessary to recharge the counterreturn chamber
140. In the case of the power control means 22, the air in the
counterreturn chamber 75 is both vented and charged through the
bleed passages 76. Therefore, reducing the size of the bleed
passages 76 (in order to cause a longer delay before the movable
member 27 returns to its forward position) results in a
corresponding increase in the amount of time needed to recharge the
counterreturn cylinder 75. And, if the movable member 27 were moved
from the first position to the second position before the
counterreturn chamber 75 is properly recharged, the benefits of the
counterreturn chamber would not be present.
A one way valve in the piston 137 would accomplish the desired
results of the extending the delaying action of the counterreturn
chamber without unduly extending the recharge time, however, the
means provided is preferred.
While only a few embodiments of the present invention have been
shown and described in detail, it will be apparent to those skilled
in the art that such is by way of illustration only. And, numerous
changes may be made to the structure illustrated without departing
from the spirit of the present invention. Further, it can be seen
that the present improved operating means could be used with an
electric powered fastener driving device. In such case, the
electrical switch for operating the electrically powered driving
device would be connected to the movable member in some suitable
manner so that the switch would be closed while the movable member
remained in the actuated position (shown in FIGS. 7 or 9).
* * * * *