US3808620A

US3808620A - Remote valve for pneumatic tool

Info

Publication number: US3808620A
Application number: US00244404A
Authority: US
Inventors: R Rothfuss; L Park
Original assignee: Senco Products Inc
Current assignee: Senco Products Inc
Priority date: 1972-04-17
Filing date: 1972-04-17
Publication date: 1974-05-07
Anticipated expiration: 1991-05-07
Also published as: DE2314209B2; JPS4920771A; NL154139B; NL7303548A; GB1386704A; DE2314209A1; JPS5134144B2

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.

Description

[4 1 May 7,1974

10/1966 Becht et 91/220 X ABSTRACT 12 Claims, 4 Drawing Figures Primary Examiner-Arnold Rosenthal Atlomey, Agent, or Firm-John W. Melville; Albert E. Strasser; Stanley H. Foster 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 I independent of variations in speed of movement of the actuatable member.

z w A III!!! ev M mraa United States Patent 1191 Rothfuss et al.-

[ 1 REMOTE VALVE FOR PNEUMATIC TOOL [75] Inventors: Robert G. Rothfuss, Bellevue, Ky.;

Lester D. Park, Cincinnati, Ohio [73] Assignee: Senco Products, lnc., Cincinnati,

Ohio

221' Filed:

Apr. 17, 1972 I [58 Field References Cited UNITED STATES PATENTS 3,730,414 8/1971 Becht.... 3,583,496 6/1971 Fehrs.................

Pmtmmm T1914 3.808.620

' sum 1 OF 2 1 REMOTE VALVE FOR PNEUMATIC TOOL BACKGROUND OF THE INVENTION This invention relates to a remotevalve 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 inthe 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, andthe 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 cylinderto drive the piston in a working stroke. Upon the closing of the main valve, the upper portion of theworking 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 onSept.

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 sufticient 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. 8

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. 2| 0,812 filed Dec. 22, 197 l 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 applicaabove 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 ofa type wherein airunder 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. I 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 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 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 thebores 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 of progressively decreasing diameters. The lowermost and 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 stern has a portion 106 of reduced diameter between the portions 102a and l02b.

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 US. Pat. No. 3,170,487 in the names of A. G. .luilfs et al. and the said copending ap plication 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. v

This upward motion of the oscillating stem will first bring the O-ring 1041? 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 l04a, 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 airfrom 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 I12 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 stern 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.

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, l02b) 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;

. 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 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 posivalve housing is slidably mounted in said tool.

Claims

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.

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.

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.