U.S. patent number 3,808,620 [Application Number 05/244,404] was granted by the patent office on 1974-05-07 for remote valve for pneumatic tool.
This patent grant is currently assigned to Senco Products, Inc.. Invention is credited to Lester D. Park, Robert G. Rothfuss.
United States Patent |
3,808,620 |
Rothfuss , et al. |
May 7, 1974 |
REMOTE VALVE FOR PNEUMATIC TOOL
Abstract
Structure for controlling the actuation of a fluid pressure
operated main valve in a pneumatic tool, including a normally
manually actuatable member which is effective upon movement to
utilize fluid pressure to shift an oscillating stem. The stem, in
turn, controls the fluid pressure acting upon the main valve. Thus,
the opening and closing of the pressure operated main valve is
dependent upon movement of the stem and independent of variations
in speed of movement of the actuatable member.
Inventors: |
Rothfuss; Robert G. (Bellevue,
KY), Park; Lester D. (Cincinnati, OH) |
Assignee: |
Senco Products, Inc.
(Cincinnati, OH)
|
Family
ID: |
22922610 |
Appl.
No.: |
05/244,404 |
Filed: |
April 17, 1972 |
Current U.S.
Class: |
91/308; 227/130;
251/29 |
Current CPC
Class: |
B25C
1/043 (20130101) |
Current International
Class: |
B25C
1/04 (20060101); F01l 025/06 () |
Field of
Search: |
;251/29
;91/308,318,461,309 ;227/130 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Rosenthal; Arnold
Attorney, Agent or Firm: Melville; John W. Strasser; Albert
E. Foster; Stanley H.
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. In a tool adapted to be connected to a source of fluid under
pressure, and having a pneumatically actuated main valve for
controlling the flow of said fluid under pressure, a cylinder and a
working piston reciprocable therein under control of said main
valve, said tool having an air return reservoir adapted to be
charged with fluid by said piston at substantially the end of its
working stroke, and having a remote valve, the improvement
comprising:
a. a valve housing (34) in said tool;
b. a first passage (56) in said housing communicating with said
main valve;
c. a second passage (54) in said housing communicating with said
supply of fluid under pressure;
d. said housing at its upper end being open and constituting an
exhaust passage (48);
e. a stem (94) providing valves (102a, 102b) slidable in said
housing between a lower position in which it connects said source
of fluid under pressure with said main valve, and an upper position
in which it connects said main valve with said exhaust passage;
f. said stem having a piston element (98) having a downwardly
extending shank;
g. a cylinder element (68) in said housing with clearance (74)
thereabout, and having a bore (76) within which the downwardly
extending shank of said piston is slidable, and a reduced diameter
bore (80);
h. a trigger valve having a shank (86) disposed in said reduced
diameter bore with clearance;
i. a passage (84) between said reduced diameter bore and said first
mentioned clearance between said cylinder element and housing;
j. a passage (108, 110) communicating, through said piston element
and its shank, between the inside of said housing and the interior
of said cylinder element below said last mentioned shank;
whereby said stem is normally biased to its lower position by said
fluid under pressure, and whereby upon actuation of said trigger
valve, said fluid under pressure has access to the underside of
said stem piston to overcome said bias, and move said stem to its
upper position.
2. The remote valve claimed in claim 1 wherein said valve housing
is slidably mounted in said tool.
3. The remote valve claimed in claim 2 wherein said valve housing
is movable between first and second positions.
4. The remote valve claimed in claim 3 including means to move said
valve housing from said first position to said second position and
back.
5. The remote valve claimed in claim 3 including means normally
biasing said valve housing to said first position, and passage
means for utilizing compressed fluid to overcome said bias and move
said valve housing to said second position.
6. The remote valve claimed in claim 5 wherein said last mentioned
passage means is effective only after said main valve has
opened.
7. The remote valve claimed in claim 1 wherein the distance of
movement of said stem between said first and second positions is
greater than the distance of movement of said trigger valve.
8. The structure of claim 1 wherein said valve housing is
reciprocable between a lower position and an upper position and is
provided with a piston element, a cylinder element for said piston
element, a passage communicating between said air return reservoir
and said cylinder element below the piston element of said valve
housing, and means for blocking said last mentioned passage;
whereby, when said last named passage is blocked, the stem is
normally biased to its lower position by said fluid under pressure,
and upon actuation of said trigger valve said fluid under pressure
has access to the underside of said stem piston to overcome said
bias and move said stem to its upper position to actuate said main
valve and thereby the working piston, and upon release of said
trigger valve to return all parts to their original position; and
when said last named passage is opened, the fluid charged into said
air return reservoir substantially at the end of the working stroke
of the working piston, is applied to said housing piston element to
move it to its upper position in which its relationship to said
stem is reestablished, and said tool then continues to operate
automatically so long as said trigger valve is actuated.
9. The remote valve claimed in claim 8 including means normally
biasing said stem to one position.
10. The remote valve claimed in claim 8 including means normally
biasing said valve housing to one position.
11. The remote valve claimed in claim 10 including means for
overcoming said last mentioned bias to move said valve housing,
whereby to effect movement of said stem.
12. The remote valve claimed in claim 8 wherein said valve housing
is slidably mounted in said tool.
Description
BACKGROUND OF THE INVENTION
This invention relates to a remote valve for a pneumatic tool
having a pressure operated main valve. Normally, the remote valve
of this invention will be manually actuatable, but it will of
course be understood that in various arrangements, automatic
mechanisms or the like can be utilized to actuate the remote
valve.
The invention has great and particular utility in connection with
pneumatic fastener applying devices. There is a vast body of patent
art describing such tools, and exemplary reference may be made to
U.S. reissue Pat. No. 26,262 in the name of A. G. Juilfs, issued on
Sept. 5, 1967 and U.S. Pat. No. 3,278,104 in the names of C. T.
Becht et al., issued Oct. 11, 1966.
According to each of these patents, the pneumatic fastener device
includes a tool body or housing having a working cylinder disposed
in the head portion. A piston and associated fastener driver are
disposed for reciprocal motion within the working cylinder.
Each of these patents also contemplates a main valve structure
which both controls the admission of compressed air into the
working cylinder, and the exhaust of compressed air from the
working cylinder. In other words, upon opening of the main valve,
air under pressure is admitted into the working cylinder to drive
the piston in a working stroke. Upon the closing of the main valve,
the upper portion of the working cylinder is vented to atmosphere
to permit the return stroke of the piston to its original
position.
Further according to these references, the main valve structure is
pneumatically actuated. More specifically, these tools each include
a remote valve which is responsive to manual actuation, and which
controls the main valve.
Reference may also be made to U.S. Pat. No. 2,954,009 in the name
of A.G. Juilfs, issued on Sept. 27, 1960, which patent describes in
detail and claims the remote valve utilized in the reissue patent
noted above. As set forth in this patent, the utilization of a
remote valve to control a pneumatic main valve has many advantages,
including, for example, a reduction in the amount of trigger
movement and a reduction in the pressure necessary to operate the
trigger. Such a valve arrangement obviously results in a tool which
is much less fatiguing to the operator.
According to all the patents mentioned thus far, actuation of the
manual trigger is effective to move a slidable member in a remote
valve, and movement of this member controls the fluid under
pressure acting upon the main valve. In other words, if the
operator very slowly squeezes the trigger of the tool, he will
cause a correspondingly slow change in the pressure of the fluid
acting on the main valve. Since the main valve is actuated by
pressure differentials, this slow squeezing of the trigger will
have a very direct effect upon the speed of operation of the main
valve.
The slowing down of the operation of the main valve has a markedly
detrimental effect on the efficiency of a fastener driving tool --
a detrimental effect which becomes more pronounced as the size of
the tool increases. Failure of the main valve of a fastener driving
tool to open quickly and completely may result in a sufficient loss
of driving power to prevent the fastener from being fully driven
into the work piece.
Keeping the foregoing comments in mind, it is a primary object of
this invention to provide an improved remote valve structure for a
pneumatic tool which will make the actuation of a pneumatic main
valve independent of the mechanical movement of the trigger.
SUMMARY OF THE INVENTION
Broadly considered, this invention contemplates a remote valve for
a pneumatic tool. The remote valve will normally be manually
actuated by means of a trigger under the control of an operator.
The remote valve of this invention includes a movable or
oscillating stem which is effective to control the fluid under
pressure acting upon the pneumatic main valve. Shifting or movement
of the stem is accomplished by means of a manually actuatable
trigger core which is effective upon movement to utilize fluid
under pressure to cause the shifting of the oscillating stem.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a cross sectional view of a pneumatic tool embodying the
remote valve of this invention.
FIG. 2 is an enlarged cross sectional view of the remote valve of
this invention in the initial position.
FIG. 3 is an enlarged cross sectional view of the valve of FIG. 2
in a second position of operation.
FIG. 4 is an enlarged cross sectional view of the remote valve of
FIG. 2 in a third position of operation.
DESCRIPTION OF THE PREFERRED EMBODIMENT
This application is closely related to and claims a portion of the
subject matter shown in application for U.S. Pat. Ser. No. 210,812
filed Dec. 22, 1971, in the names of Robert G. Rothfuss et al.
FIG. 1 illustrates somewhat schematically a fastener driving tool
with which the remote valve of this invention may be utilized. A
detailed description of other aspects of this tool is set forth in
the copending application referred to above. For present purposes,
the tool includes a housing having a head portion indicated
generally at 10. The working cylinder 154 for the tool is disposed
within the head portion 10, and a piston 146 and driver assembly
are reciprocable in the working cylinder in opposed working and
return strokes.
At the top of the working cylinder is a suitable pneumatically
operated main valve 122, fully described in said copending
application. Reference is made to U.S. Pat. No. 3,170,487 in the
name of A. G. Juilfs et al. issued on Feb. 23, 1965 for a full
description of another form of a pneumatically operated main valve.
The valve shown in FIG. 1 is that of said copending application,
and it is only necessary to point out that the valve 122 is a part
of the cylinder 154, and cooperates with the seat 120. An air
return reservoir, described in said copending application, is shown
at 154. For present purposes, it is sufficient to note that the
main valve is movable between two positions. In the open position,
the main valve admits compressed air into the working cylinder to
drive the piston in its working stroke. In the closed position, the
portion of the working cylinder above the piston is vented to
atmosphere so that the piston may be returned to its initial
position.
The pneumatically actuated main valve according to U. S. Pat. No.
3,170,487 is of a type wherein air under pressure is normally
admitted against the top surface of the valve to bias it to the
closed position. Upon exhaust of that air, the main valve will be
opened. Admission of further compressed air to the top surface of
the main valve will cause it to close again.
The tool shown in FIG. 1 also includes a handle portion indicated
generally at 12, within which the remote valve indicated generally
at 14 in FIG. 1 will be mounted. The interior of the handle portion
12 defines a reservoir 16 which will be in communication with a
supply of air under pressure. This tool will be cycled by manual
actuation of the trigger 18.
Turning now to FIGS. 2, 3 and 4, the remote valve of this invention
will be described in detail. It will be recalled from FIG. 1 that
the remote valve is mounted in the tool casting at essentially the
juncture of the handle portion 12 and the head portion 10, and
extends through the reservoir 16. In FIGS. 2 through 4, fragmentary
portions of the tool casting are indicated at 20 and 22.
The lower portion 22 of the casting is provided with the bores 24,
26, and 28. The upper portion of the casting 20 is provided with
the bores 30 and 32. The upper end of the bore 30 will be closed in
part by a cap (not shown in these figures) which will be provided
with a passage to atmosphere.
The valve housing or sleeve indicated generally at 34 is slidably
received within the bore 24. It will be observed that the lower
portion of the housing 34 is enlarged at 36 and provided with the
O-ring 38 for sealing engagement with the walls of the bore 24. The
upper portions 40a and 40b (which are of the same diameter) are
slightly larger than the central portion 42 of the housing and
noticeably smaller than the enlarged portion 36. The portions 40a
and 40b are provided respectively with the sealing O-rings 44 and
46.
Internally, the valve housing is provided at its upper and lower
ends respectively with the bores 48 and 50. Intermediate these
bores is the bore 52 of somewhat smaller diameter.
The valve sleeve is also provided with the radial apertures 54
providing communication between the bore 50 and the reservoir 16,
and the radial apertures 56 providing communication between the
bore 52 and the exterior of the sleeve between the O-rings 44 and
46.
The bores 30 and 32 in the casting portion 20 are each at least as
large as the bore 24 in the casting portion 22. Thus, the valve
sleeve can be placed in position through the top of the tool before
the cap is secured in place. The spacing sleeve 58 may then be
positioned in the bores 30 and 32. Sealing engagement between the
external surface of the sleeve 58 and the bores 30 and 32 is
accomplished by means of the O-rings 60 and 62. The sleeve is
provided with the radial bores 64 between the O-rings 60 and 62
which communicates with the relieved area 66 on the interior of the
sleeve.
Disposed within the lower portion of the bore 50 of the valve
sleeve is the trigger housing 68. The trigger housing is provided
on its exterior with the O-rings 70 and 72 which respectively
maintain sealing engagement with the bore 50 in the housing 34 and
the bore 26 in the casting portion 22. The upper portion of the
trigger housing 68 is of reduced diameter so as to define an
annular space 74 within the bore 50. The interior of the trigger
housing is provided with the bores 76, 78, and 80 of progressively
decreasing diameters. The lowermost end of the trigger housing may
be provided with the relieved area 82. Finally, the trigger housing
is provided with one or more radial ports 84 extending between the
annular space 74 and the bore 80.
Slidable within the trigger housing is the trigger core 86. The
trigger core 86 has an enlarged end 88 provided with the O-ring 90
to maintain sealing engagement in the bore 78 in the position
illustrated in FIG. 2. The trigger core is also provided with the
O-ring 92, which in the position shown in FIG. 2 will be disposed
in the relieved area 82. Upon upward movement of the trigger core,
the O-ring 92 will of course move into sealing engagement with the
bore 80. It will be understood that the fit between the trigger
core 86 and the bore 80 is not air-tight. In other words, the
annular space 74 is in effect vented to atmosphere via the passage
84, through the passage 80, the relieved area 82 and the bore
28.
Slidably disposed within the upper portion of the valve housing 34
is the oscillating stem indicated generally at 94. The lowermost
end of the stem 94 is provided with the O-ring 96 for sliding,
sealing engagement in the bore 76. An intermediate portion 98 of
the oscillating stem is of enlarged diameter and carries the O-ring
100 for sliding, sealing engagement in the bore 50 of the valve
housing.
The upper end of the oscillating stem 94 includes the portions 102a
and 102b of the same diameter, provided respectively with the
sealing O-rings 104a and 104b. The oscillating stem has a portion
106 of reduced diameter between the portions 102a and 102b.
The oscillating stem is also provided with a cross bore 108
disposed between the O-rings 104b and 100, and an axial bore 110
extending from the cross bore 108 through the lower end of the
stem.
The operation and interaction of the components previously
identified will now be described. The components are illustrated in
FIG. 2 in the normal or starting position. With the tool connected
to a suitable supply of air under pressure, the handle reservoir 16
will of course be filled with such air under pressure. Air from the
reservoir may pass through the radial port 54 in the valve housing,
past the O-ring 104b, through the ports 56 in the valve housing,
through the ports 64 in the spacing sleeve, and into the passage
112 in the casting portion 20. The passage 112 communicates with a
portion of the main valve of the pneumatic tool. Reference is again
made to U.S. Pat. No. 3,170,487 in the names of A. G. Juilfs et al.
and the said copending application for a description of
pneumatically actuated main valve which may be used with the remote
valve of this invention. According to that patent and the
application, compressed air passing through the passage 112 is
effective to hold the main valve in the closed position.
It will be apparent that the effective area of the portion 98 of
the oscillating stem is greater than the effective area 102a. Thus,
the compressed fluid passing through the radial ports 54 with the
components in the position shown is effective to bias the
oscillating stem downwardly to the position shown.
Air passing through the ports 54 can also pass through the cross
bore 108 and axial bore 110 so as to act downwardly on the top
surface of the portion 88 of the trigger core, normally air biasing
this element to the down position. The annular area 74 will be
vented to atmosphere via the radial port 84 and the clearance
between the bore 80 and trigger core 86.
It will also be apparent that the effective cross sectional area of
the portion 36 of the valve housing is greater than the effective
area of the portion 40b of the valve housing. Therefore, air in the
reservoir will normally bias the valve housing to the down position
as shown in FIG. 2.
To operate the tool, the operator will depress the manual trigger
18, thereby raising the trigger core 86 to the position shown in
FIG. 3. This upward motion of the trigger core will first bring the
O-ring 92 into sealing engagement with the bore 80, thereby cutting
off the exhaust for the annular space 74. The O-ring 90 will then
move out of sealing engagement with the bore 78 and into the bore
76. This will permit compressed air from the reservoir to pass
through the ports 54, the cross bore 108, the axial bore 110,
around the O-ring 90, through the radial bore 84, and into the
annular space 74. At this point, the air under pressure is
effective to act upon the underside of the portion 98 of the
oscillating stem. This overcomes the air bias previously referred
to and rapidly shifts the oscillating stem upwardly to the position
shown in FIG. 3.
This upward motion of the oscillating stem will first bring the
O-ring 104b into sealing engagement with the bore 52. This will
clearly prevent further compressed air entering the ports 54 from
passing to the radial ports 56.
Shortly thereafter, the O-ring 102a will move into the bore 48 and
out of sealing engagement with the bore 52. As previously
indicated, this will open a passage to atmosphere. Specifically,
air holding the main valve of the pneumatic tool closed may pass
through the passage 112, through the radial ports 64, through the
radial ports 56, past the O-ring 104a, and out the exhaust passage
in the cap referred to earlier. This exhaust of the air holding the
main valve closed will of course permit it to be opened
pneumatically. This, as is well known in the art, will initiate the
working cycle of the tool and cause the piston to be driven rapidly
downwardly, thereby driving a fastener into a work piece.
When the operator releases the manual trigger 18, the compressed
air from the reservoir acting on the top surface of the portion 88
of the trigger core will force it downwardly, back to the position
shown in FIG. 2. This of course brings the O-ring 90 into sealing
engagement with the bore 78, and moves the O-ring 92 into the
relieved area 82, permitting exhaust of the compressed fluid in the
annular area 74. When this area is exhausted, the air bias referred
to earlier will move the oscillating stem back downwardly to the
position shown in FIG. 2, and compressed air will once again be
admitted into the passage 112 to close the main valve.
The copending application in the names of Rothfuss et al., as well
as a variety of other, issued U.S. Pats. such as No. 3,278,104 in
the names of Becht et al., teach an automatically reciprocating
fastener applying device. According to these patents, the pneumatic
tool will continuously and repetitively cycle so long as the
operator maintains the manual trigger in the actuated position. The
remote valve of this invention is designed to accomplish such
repetitive cycling. To this end, the portion 22 of the tool casting
is provided with a passage 114 which will be supplied with air
under pressure from the return air reservoir 154 only when the
working piston has reached substantially the end of its working
stroke.
In other words, assume that the trigger has been actuated by the
operator and the components of the remote valve are in the
positions shown in FIG. 3. The main valve of the tool has been
opened and compressed air has driven the working piston downwardly
in its working stroke. As just indicated, at substantially the end
of that stroke, compressed air will be delivered to the return air
reservoir 154 through the passage 166. This compressed air is
delivered to the passage 114 via the passage 152 and the mode
selector valve 150.
This compressed air from the passage 114 can act upon the underside
of the portion 36 of the valve housing, overcoming the air bias
referred to earlier. This will move the valve housing upwardly to
the position shown in FIG. 4. In other words, the valve housing is
moving upwardly relative to the oscillating stem, so that the
relative positions of these components is the same as in FIG. 2.
Compressed air can pass through the ports 54, past the O-ring 104b,
through the ports 56, the ports 64, and into the passage 112
briefly closing the main valve, even though the manual trigger 18
remains actuated.
Upon the closing of the main valve, the space in the working
cylinder above the piston will be exhausted to permit the return of
the piston to its starting position. This will also exhaust the air
from the passage 114, and the air bias will move the valve housing
downwardly to the position shown in FIG. 3. As previously
described, this relative positioning of the oscillating stem and
valve housing will cause the opening of the main valve.
It is believed that the construction and operation of the remote
valve of this invention should be clear from the foregoing
description. Several points may be noted in conclusion.
First of all, it will be observed that the opening and closing of
the main valve is controlled by movement of the oscillating stem.
The oscillating stem in actual practice is extremely light in
weight, and pneumatically actuated. Thus, its movement is extremely
rapid.
Secondly, as briefly mentioned above, movement of the oscillating
stem is pneumatically controlled. That is, it is normally air
biased down. As soon as the total upward force on the oscillating
stem is greater than the total downward force, just cracking the
lowermost seal, air under pressure can effectively be applied to
the entire bottom surface of the stem, very rapidly moving it to
the full up position.
Thirdly, it will be observed that the stroke of the oscillating
stem is substantially longer than the stroke of the trigger
core.
These three factors in combination make the operation of the main
valve almost completely independent of the touch of the operator on
the manual trigger. Even if the operator were to very slowly
squeeze the trigger, thereby slowly bleeding air past the O-ring
90, the shifting of the oscillating stem would be rapid and full.
The longer stroke of course provides for greater exhaust area,
thereby in combination accomplishing a very rapid exhaust of the
air holding the main valve closed.
It is believed that the foregoing constitutes a full and complete
disclosure of this invention. No limitations are intended except
insofar as specifically set forth in the following claims.
* * * * *