US3081742A

US3081742A - Pneumatically operated fastener driving machine

Info

Publication number: US3081742A
Application number: US735740A
Authority: US
Inventors: John E Goldring; Arthur E Kremiller
Original assignee: Modernair Corp
Current assignee: Modernair Corp
Priority date: 1955-11-14
Filing date: 1958-05-16
Publication date: 1963-03-19
Anticipated expiration: 1980-03-19

Description

PNEUMATICALLY OPERATED Original Filed Nov. 14, 1955 FASTENER DRIVING MACHINE 3 Sheets-Sheet 1 cs P7 1 h ervibr's o JOHN E. COLORING Z3 ARTHUR E KREM/LER I a M W 9 Mam v 19, 1963 J. E. GOLDRING ETAI. 3,

PNEUMATICALLY OPERATED FASTENER DRIVING MACHINE Original Filed Nov. 14, 1955 5 Sheets-Sheet 2 W W I a Fig 5.,

ii. rates 18 (Ilaims. cl. i21 21 The present invention relates to improvements in pressure fluid operated fastener driving machines.

This application is a division of application Serial No. 546,509 filed November 14, 1955.

The use of pressure fluid such as compressed air, CO or other gases for motivating fastener driving devices has received considerable attention in view of the increasing use in industry and various trades of machines for driving various types of nail or pin or staple fasteners in se curing together members that heretofore may have been manually nailed together. By motivating the fastener driving machines pneumatically (that is, by a compress ible pressure fluid) reduction in weight of the mechanism, greater and more positive driving force as well as substantial reduction in strain and fatigue upon the operator can be attained.

However, the harnessing of the fluid force to the specific function of motivating a fastener driving device has presented certain definite problems among which the most serious problem has been that of objectionable recoil on the order of that unleached as a result of the explosive forces generated in firing a weapon type of gun. This has been caused in pneumatic fastener drivers apparently by reason of the similar reaction in the chamber space behind the piston as occurs in the chamber space behind the projectile or bullet in a firearm where the expanding gases of the explosive charge react toward the head of the chamber opposite the projectile, thereby tending to move the gun away from the projectile which is moved by the expanding gases toward the muzzle of the gun where the gases can exhaust. The same principle operates in a jet type fluid motor where the pressure created against the unyielding head of the chamber in which the expanding gases are confined creates a thrust in the di rection of the head. In a pneumatic fastener driving gun such reaction of the compressed gas in the piston chamber or cylinder is toward the head end thereof and this is reflected in a recoil or hopping action of the machine, and more especially in those machines where the compressed gas is introduced into the head space above the piston Without any initial restraint upon stroking movement of the piston as the pressure fluid is suddenly released under driving pressure into the cylinder.

It is accordingly an important object of the present invention to provide a pneumatically operated fastener driving device in which there is substantially complete freedom from fluid pressure recoil incident to the driving stroke of the fastener driver.

Another object of the invention is to provide pneumatically actuated fastener driving means in which the transition from at rest or non-operating to the full effective fluid pressure actuated driving stroke is accomplished smoothly and without recoil reaction.

A further object of the invention is to provide a fastener driving mechanism in which greatly increased efficiency in the use of compressed gas such as air is attained both with respect to the volume of gas used in a driving stroke and in the positive application of the energy derived from the gas actually used.

Still another object of the invention is to improve the 3,fl8l,742 Patented Mar. 19, 1963 "ice speed of operation and the positive control of pneumatically operated fastener driving devices.

A still further object of the invention is to provide improved safety features for pneumatically operated fastener driving machines.

It is an additional object of the invention to simplify and improve the construction and assembly of pneumatically operated fastener driving machines for economical mass production, ease and convenience in servicing, and rugged trouble free service.

Other objects, features and advantages of the present invention will be readily apparent from the following detailed description of certain preferred embodiments thereof taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a side elevational view of a pneumatic fastener driving machine unit constructed and arranged to be mounted upon a suitable fastener carrying or magazine body member or assembly;

FIGURE 2 is a top plan view of the unit shown in FIGURE 1;

FIGURE 3 is a front end elevational view of the pneumatic unit;

FIGURE 4 is a fragmental, enlarged vertical longitudinal sectional view through the unit shown in FIG- URES 1 to 3, taken substantially along the section line IVIV of FIGURE 2 and showing the unit mounted upon a fastener carrying body assembly which is more or less schematically illustrated partly in elevation and partly in section; and

FIGURE 5 is a fragmentary vertical sectional view taken substantially in the same plane as FIGURE 4 but showing only the front end or head portion of the pneumatic unit with the driver and the pneumatic control mechanism illustrated in relative positions assumed during a driving stroke.

In a practical embodiment of the invention a pneu matic driver unit 15 (FIGS. 1, 2 and 3) is constructed and arranged to be mounted upon a body assembly 17 (FIG. 4). As a principal component, the driver unit 15 includes a casing structure which is preferably constructed as a casting of a suitable light weight material such as a suitable aluminum alloy. Such casing comprises an elongated hollow handle portion 18 extending rearwardly from a vertically and laterally enlarged hollow head end portion 19. At its upper end the head portion 19 is open but is operatively closed by a crown closure 26. At its lower end the head portion 19 is provided with a depending boss 21 about a lower opening and to which boss is attached a lower closure member 22 as by means of screws 23.

For attaching the driver unit 15 to the body assembly 17, means such as a pair of spaced depending ears 24 on the rear portion of the handle section 18 are adapted to straddle an upwardly directed attachment boss 25 on the body assembly with suitable means such as attachment bolts 27 extending through suitable aligned apertures 23 in the ears and in the boss 25 and thereby removably secure the rear portions of the driver unit and the body assembly together. Attachment of the forward portion of the body assembly 17 to the driver unit may be accomplished as shown by means of a bolt 29 extending through aligned apertures 30 in a pair of spaced rearwardly extending attachment cars 31 projecting rear- Wardly from the lower closure member 22 and straddling a forward portion of the body member 17 provided with a bolt hole aligned with the ear apertures 3t}. Thus, by means of the substantially fore and aft yoke-like attachment means described quick assembly or disassembly of the driver unit 15' and the body assembly 1'7 can be effected, and the driver unit 15 is adaptable to be mounted aoermsa selectively upon body units or assemblies that are constructed and arranged for supporting and feeding into position for driving any of a variety of fasteners such as pins, nails, or staples, the fasteners in FIGURE 4 being shown as pins 32 of the type commonly referred to as sash pins which are supported in suitable multiples such as in stick form within a longitudinal magazine 35 in the body assembly 17 and fed forwardly therein by suitable feed or pusher mechanism (not shown) carried by the body assembly.

At the front end of the body assembly 17 under the head portion 19, and more particularly the bottom or base closure member 22 thereon are provided means for presenting each of the fasteners 32 successively in position to be driven by a driving blade 34 operatively associated with the driving unit 15. In the present instance such means comprise a facing plate 35 having a doorway aperture 37 for passage of the fasteners forwardly therethrough into a vertical driveway 38 defined between the plate 35 and a forward nose piece 39. At their upper end portions the facing plate 35 and the nose piece 39 have respective rearward and forward portions that abuttingly underlie the lower closure member in the assembly with the upper end of the driveway 38 aligned with a driver passage opening 40 in the closure member so that the lower end driving tip portion of the driver can normally be supported slidably in the guideway 33 immediately above the foremost of the fasteners to be driven.

vFor conveniently manually carrying and positioning the machine for driving the fasteners 32 from the driveway 38 into members to be fastened the handle portion or section 18 is preferably shaped longitudinally to extend rearwardly obliquely convergently toward the rear end portion of the body member 17 from the head portion 19 for a suitable length or distance to overlie a hand hole body depression 40, with the remainder of the handle portion extending generally rearwardly and providing a palm depression 4 1 at the juncture of the oblique and terminal rear portion of the handle. The construction and arrangement are such that the forward portion of the handle section 18 can be conveniently held with the fingers of the manipulating hand underneath the handle and the palm above with the thumb projecting forwardly over a control valve assembly 42 at least in part exposed outside of the machine casing and mounted adjacent juncture of the upper portion of the front end of the handle With the head .19 between a pair of laterally spaced upwardly and rearwardly projecting safety flange guard cars 43. The cars 43 project sufficiently beyond a depressible valve head or buttom 44 to avoid actuation thereof accidently but requiring that the operators finger or thumb be moved into engagement therewith between the guard ears or ribs 43.

According to the present invention, depressing of the valve button or head 44 results in instantaneous smooth recoiless pneumatic driving of the driving blade 34. This is accomplished by operating the valve assembly 32 to leed air or other pressure fluid under pressure from a chamber 45 in the upper end portion of the head '19 to cause pneumatically responsive means in the form of a diaphragm closure valve member comprising a control piston 47 to be driven (PEG. from a top closure seat 48 on which it normally engages (FIG. 4) at the upper lip end or extremity of a cylinder barrel or boss 49 that projects upwardly within and exposed to a surrounding rnain pressure fluid chamber 50 inside the head 19. This permits fluid under pressure to spill or expand (see directional arrows, PEG. 5) instantaneously from the chamber 50 over the seat 48 into the ingress opening of the cylinder onto the top of a driving piston 51 to which the upper end portion of the driving blade 34 is attached, thus depressing the driving piston against the 4 action of biasing means such as a spring 52 to actuate the driving blade in a driving stroke.

Since the pressure fluid about the seat lip 4-3 in the reservoir St) is already under full pressure head and is of large volume, including not only the immediately surrounding area in the reservoir chamber 56, but also a large unrestricted throat area 53 leading into and connecting unrestrictedly a large supplementary or auxiliary reservoir chamber 54 throughout substantially the length of the handle section -18, driving of the piston 51 occurs with uni-directional thrust of the air expanding into the cylinder onto the head of the piston 51. There is no recoil because instead of an explosive build-up of energy in the area over the piston head there is, on sudden complete exposure of the piston head to the fluid pressure, actually only escape of fluid from a static volume to which the cylinder head is exposed. Therefore, all of the dynamic pressure thrust is toward the drive piston 51 and not in an upward or rebound direction.

To the attainment of these desirable results, the control valve 42 is a normally closed bleeder valve having attached to the button head 44 a stem 55 carrying a taper faced, O-ring seal valve assembly 57 at the opposite or inner end from the head 44 and normally urged into closing, sealing relation against a complementally tapered valve seat 58 at the inner end portion of a valve sleeve bushing 59 housing a valve biasing compression spring 6% Normally the valve '57 is held on its seat 58 by the biasing spring 60 and fluid pressure, as shown in FIGURE 4. For opening the valve, pressure applied to the valve head 44 overcomes the biasing spring 69 and unseats the valve 57 as shown in FIGURE 5, thereby opening a bleed-off comprising an exhaust passage through the sleeve bushing 59 and vent openings 61 therefrom.

Herein the valve bushing 59 is threaded into the outer end portion of a rearwardly and upwardly oblique blind end bore 62 in the driver unit casing. The inner end portion of this bore communicates by way of a con trolled substantially unrestricted passage from the reservoir, affording a duct 63, with the upper portion of the auxiliary pressure or control piston chamber 45. Thus, when the valve 57 is opened, the control piston chamber 45 is opened to atmosphere and any fluid pressure therein will bleed ofr".

When the valve 57 is closed, fluid under pressure from the chamber 50 forwardly from the throat area d3 bleeds through a continuously open restricted metering orifice 6 and a bore duct 65 that intersects the bore duct 63 for delivery of the pressure fluid through the port provided by the duct 63 into the control piston chamber 45. Pressure thus created in the chamber 45 tends to hold the control piston 47 in closing relation upon the driving piston cylinder head seat 48. At its upper end the bore duct 65 is effectively sealed by a gasket 57 clamped against the top of the head 19 by the closure member 20 which is held removably in place by means such as screws 68.

The relative proportions in cross-sectional flow area of the restricted metering orifice 64 and the substantially larger diameter bleed-off duct 63 are such that although in the closed condition of the control valve 57 ample biasin fluid pressure is supplied through the orifice 64 to the control piston chamber 45, in the open, bleed-off condition of the valve 57 virtually instantaneous pressure drop is attained in the chamber 45 and the pressure drop across the orifice 64 is suiiicient to avoid any appreciable loss of pressure from the pressure chamber 50 that surrounds the cylinder 49.

In order to assure positive action of the control piston 47 responsive to fluid pressure in both directions, it is preferably of substantial diameter and effective area on both sides. To this end the piston 47 is constructed of a diameter substantially larger than the external diameter of the cylinder 49 immediately adjacent to the valve seat 43, and an internal cylindrical surface as in the upper end portion of the head 19 is provided concentric with the cylinder 49 for cooperation with the annular periphery of the piston 47. By preference, a fluid seal is provided in such annular periphery as by means of an O-ring 7%. Since the range of reciprocal movement of the control piston 47 may be fairly short it will be appreciated that only moderate head room need be provided above the control piston valve seat 48. In such short head room the control piston chamber 45 is of small volume so that bleed-off is accomplished with great speed in the operation of the device. Moreover, the over-all height of the head section of the machine can thus be maintained at a minimum.

In view of the short working stroke of the control piston valve member 47 it is preferably mechanically biased normally toward its seat 43. Herein this is accomplished by means of a coiled compression spring 71 thrusting under compression against the upper face of the piston and against the opposing surface of the closure member 20. The compression loading of the biasing spring 71 is, of course, substantially less than the force exerted by pressure fluid in the chamber 50 upon the inner or lower dynamic pressure surface of the piston valve :7 exposed to the main pressure chamber 59.

In order to limit unseating or blow-off, or back-01f movement of the piston valve 47 depending limit stop means such as an annular flange 72 may be provided on the inner face of the closure member 29, with the biasing spring 72 accommodated within a central recess 73 encircled by the stop flange. Entrapment of fluid in the recess 73 is avoided by a transverse relief port 74- in the stop flange 72, preferably substantially aligned with the port opening into the bleed-off bore 63. To limit contact, and thus minimize possibility of sticking of the piston valve 47 to the flange 72, a limited area contact shoulder 75 is provided on the upper face of the piston valve' In order to assure an effective seal between the control piston valve member 47 and the seat 48 to avoid leakage of air into the cylinder 49 in the non-operating condition of the machine, a resilient valve disk 77 is mounted on the lower side of the piston valve. This valve disk is of such resilient deflectability as to assure thorough sealing conformity to the valve seat 4-3 under the com 'bined biasing spring and air pressure working against the piston valve in its seated position during non'operating periods.

In order to enable ready replacement of the resilient valve disk 77, it is attached to the piston 47 at an inner margin with the side or face thereof opposite the valve seat-engaging face in loose abutment to the valve piston member. Hence, the valve disk 77 is in the form of an annulus with an inner margin that extends substantially inwardly beyond the inner edge defining the valve seat 43 and is clamped to the piston member 47 by a flange 78 on a central sleeve or bushing member 79 threadedly secured into a central bore 843 within the piston 47. However, the sealing valve disk 77 is of a diameter not only to effect full sealing engagement over the entire width of the seat 43 but also to extend marginally beyond the outer side of the seat to aflord exposure to the pressure of fluid in the chamber 50. This assures that the valve disk 77 will back away from and provide a substantial, uniform air gap between the valve seat 48 and the piston valve for release of fluid into the cylinder and thus as nearly as practicable instantaneous full acceleration of the driving piston 51 for uniform pushing thrust of the driving blade 34 toward and against the head of the fastener 32 to be driven.

It will be observed in FIGURES 4 and 5 that the flange 78 is of smaller diameter than the inside diameter about the valve seat 48 so as to be received freely therein, while the valve disk 77 projects laterally substantially beyond the outer side of the valve seat. As a result, during backing off movement of the piston 47 the flexible resilient valve disk 77 under the influence of fluid pressure initially on its outer margin and thereafter fully on its exposed face assures lack of any initial drag in opening movement away from the seat 48 but instantaneous large entry opening into the cylinder 49 as the piston valve snaps open toward the stop flange 72 because the valve disk clings to the valve piston 47.

For guiding reciprocal movements of the piston valve 47 a guide stem 31 is carried rigidly by the closure mern ber 20 concentrically with the piston 47 and is slidably embraced by the sleeve bushing member 79. In addition, the guide stem 81 serves as a piston displacement vent above the drive piston 51. To this end, the lower or inner end portion of the stern has a short blind end bore 82 that communicates by way of a plurality of lateral ports 33 with an annular channel 84 in the inner periphery of the sleeve bushing 79 and which is in communication with the ports 83 in the seated position of the valve piston but is shifted out of communication with the ports 83 in the unseated position of the piston valve as shown in FIGURE 5. Venting communication from the groove or channel 34 is through a series of lateral ports 85 spaced above the ports 83 and communicating with the inner end portion of an upper blind end bore 87 within the stem 31 opening from the top thereof to atmosphere above the closure member 20. Through this arrangement, when the piston valve 47 is seated upon the cylinder a vent to atmosphere is opened for exhausting pressure fluid above the drive pison 51 incident to its return from a driving stroke. Yet, when the piston valve 47 is unseated the vent is immediately closed off to prevent escape of pressure fluid from within the unit. It will be observed that appropriate seals such as O-ring seals are provided at appropriate interface areas of the stem 81 and the bushing sleeve 79.

Since for smooth and substantially frictionless operation of the moving parts, it is desirable to entrain in the compressed iiuid supplied to the machine a small amount of lubricant, guard means in the form of a baflle cap 88 are preferably provided to overlie the exhaust port at the upper end of the vent bore 37 to prevent spraying of the oil up into the air incident to the rushing exhaust of fluid from the vent. The cap 38 may be secured in place by means of screws 8% with a downturned annular marginal flange 96 of the guard cap seated on spacer lugs or projections 91 on the top of the closure member 20.

Normally the drive piston 51. is held by the biasing spring 52 against an annular inwardly facing shoulder 92 located as closely as practicable to the oppositely, upwardly facing seat 48. Since provision of the stop shoulder 92 provides an annular overhanging portion about the seat 4%, a compensating annular upper outer marginal groove 93 is provided adjacent the outer sideof the seat 43 in order to maintain the seat at a minimum width to avoid frictional or drag losses in movement of compressed fluid over the seat upon unseating of the piston valve 47.

A desirable relationship between the periphery of the driving piston 51 and the surrounding cylinder wall comprises a free clearance relationship and with sealing means such as an G-ring $4 operatively seated in the piston periphery.

To provide a return spring centering and buckle-preventing guide, the drive piston 51 is provided with a central smaller diameter depending boss 95 about which the upper end portion of the spring is disposed. This boss 95 also provides means for connecting the driving blade 34 to the piston. For this purpose, the upper end portion of the blade 34 extends upwardly into a downwardly opening slot 97 in the boss. For removably connecting the driving blade to the driving plunger or piston 51, retaining means may be provided in the form of pin means such as an elongated key member 98 extending through a transverse bore 99 in the boss 95 and through a matching aperture in the head end portion of the blade 34.

in order to limit the driving stroke of the driving blade 34 to the desired extent, stop means are provided in the lower portion of the cylinder. In the present instance the stop means combine the function of vibration damper and return spring holder. To this end a generally cup shaped member 100 is provided having a central aperture N1 for passage of the driving blade 34 and providing an annular inturned flange 102 upon which the lower end of the return spring 52 thrusts. At its upper end the member lit-1 is provided with a lateral annular flange 10? which in assembly rests upon an annular resilient cushioning or vibration darnpin member 1% which in turn rests against the upper face of the lower closure member 22, while the lower end portion of the member 101 extends down into a clearance recess 105 affording limited floating movement of the spring retainer and bumper member 100 resting upon the cushioning ring 104.

The upper edge of the stop member flange 103 opposes the lower side of the margin of the drive piston 51 and is engageable by a resilient annular bumper ring m7 of preferably a resiliently flexible or elastic material such as rubber or other elastomeric material carried by the piston. In the present instance a convenient retainer for the resilient bumper 167 comprises a generally channel shaped radially outwardly opening ring member 1th, within which the bumper N7 is seated and having the lower flange of the channel substantially narrower than the width of the bumper 1G7 so as to expose a substantial annular lower outer marginal portion of the bumper ring for engagement with the stop flange 1%. For retaining the retainer ring 1% in place on the underside of the piston 51, an upper inner marginal radially inwardly projecting annular seat flange M9 is provided thereon engaged by the upper end of the return spring 52 which thereby constantly thrusts the retainer ring 1 33 against the piston. Through this arrangement, at the end of the driving stroke of the piston 51, as shown in FIGURE 5, the bumper 1M impacts against the stop flange iii-3 and cushions the stopping of the piston in conjunction with the shock absorbing and cushioning ring H24, the lower side of the ring channel being accommodated within a flaring mouth 110 within the inner side of the flange 1W3, such mouth being beveled or chamfered to ease the return spring 52 into the recess provided by the retainer and stop member 1% during compression of the spring. It will also be observed in FIGURE 5 that in the drive stroke limit position of the piston 51, the depending spring guide boss 95 cooperates with the cylindrical wall of the retainer it?!) to hold the coils of the spring against undue lateral displacement, which is a desirable relationship to maintain highest efliciency in the spring.

To provide for free breathing within the cylinder 49 under the piston 51 vents are provided herein comprising a plurality of vent ports 111 which may conveniently open into the lower end portion of the cylinder through the front wall of the head 1% (FIGS. 3, 4 and 5). Where, as herein, the stop flange res projects upwardly protectively past the vent ports 111, an annular communication channel 112 in the outer periphery of the flange 1% has ports 113 through the flange leading from the interior of the retainer lfitl within the cylinder. "In addition, vent port's 114 preferably lead from the lower end of the cavity 195 to the outside of the lower closure member 22.

Provisions are made for connecting the reservoir Si), '53, 54 within the unit with a suitable direct and continuous source of pressure fluid under substantially constant pressure and from which pressure the reservoir is not disconnected throughout the operation of the machine. To this end, the rear extremity of the handle 13 is preferably provided with a threaded inlet port 115. Into this inlet port is secured an internally threaded hose nipple receiving member 1E7 provided with a safety inlet orifice 118. While the orifice 118 will normally allow pressure fluid to maintain the reservoir filled, this orifice assures a suflicient pressure drop upon or restriction upon initial inrush of fluid when the machine is first quickconnected to the fluid source to prevent premature firing of the drive piston. That is, in view of the small size of the valve piston hold down bleed orifice 64 there would be a tendency of the valve piston 47 to be blown from its seat in the initial inrush of pressure fluid air into the reservoir. Therefore, by restricting such inrush through the inlet orifice 113 there will be a suflicient restraint or drag or throttling upon initial filling of the reservoir with pressure fluid to enable the piston valve holding pressure bleed through the orifice 64. After the initial filling of the reservoir, of course, a substantially pressure filled condition is maintained therein as long as connection to the pressure source is maintained and therefore the premature firing problem is only encountered at the initial introduction of pressure fluid into the reservoir.

Where attachment of the machine to a fluid supply hose at one side of the head 19 is preferred or more expedient, the inlet orifice 115 may be plugged and the hose attached to a side boss 119 (FIGURE 2) providing an inlet 120 (FIGURE 4) from which leads a restricter orifice 121 bored into the wall of the reservoir and of preferably the same cross-sectional flow area as the restricter orifice 113.

From the foregoing it will be apparent that in the use of the fastener driving machine, it is manipulated by the handle 18 into working position and then under full working pressure head or potential energy within the large reservoir within the casing of the unit 15, simple pressing of the valve head 44 results in the substantially instantaneous blowing off, of the piston valve 4-7 and fluid pressure thrusting of the driving piston 51 in a driving stroke. The most efiicient reservoir pressure head for any given size of machine or fastener to be driven may be readily determined. For certain heavier types of fasteners available line pressures up to p.s.i. have been used. As long as the valve 57 is held open the control valve piston 47 will remain unseated due to the differential in pressure thus maintained. Promptly upon closing of the valve 5'7, pressure bleed through the metering orifice 6d supplements the piston return spring 71 to return the piston valve 47 to its seat 48, thus closing the piston off from the pressure within the reservoir and at the same time venting the cylinder above the piston to atmosphere through the stem 81, whereupon the drive piston 51 snaps back against the stop shoulder 92. In addition, due to the substantial area on the underside of the valve piston 47 thus relieved of pressure and vented to atmosphere and opposed by pressure within the head chamber 45, or, stated alternatively, due to the greater area of its surface exposed to the pressure in the auxiliary or head chamber 45 than the area of its surface exposed to the pressure in the main chamber 50, a strongly unbalanced pressure relationship is maintained assuring that the valve piston 47 will during non-operating but pressure filled condition of the unit be normally pressed strongly against the valve seat 48 so as to avoid leakage of pressure fluid into the drive piston cylinder. 7

Since there is always a large reserve volume of pressure fluid within the reservoir about the cylinder 49, the comparatively small volume of air that spills over into the cylinder i-9 incident to driving of the drive piston 51 has virtually no pressure dropping or dissipating effect. This is especially true because the reservoir is in continuous, open replenishing communication with the pressure fluid source. In practice it is desirable to provide up to ten times the volume of compressed air within the reservoir as compared to the total volume spent on each driving of the drive piston 51, that is, the volumetric displacement above the piston 51 within the cylinder 49 at the end of the driving stroke as depicted in FIG- URE 5, depending on the power required.

in View of the immediate full pressure thrust upon the driving piston 51 at the instant of opening the top of the cylinder 49, the volumetric displacement of pressure fluid required to drive the piston with high velocity thrust can be maintained at a minimum. It is, therefore, practical to operate the machine of the present invention with substantially less pressure fluid than has been heretofore possible in fastener driving machines wherein line drag, which is entirely absent in the instant system, has required a wasteful use of fluid in order to attain the desired velocities and power.

It may be pointed out, that while ideally the valve seat lip 48 on the cylinder 4-9 is preferably exposed uniformly about its entire perimeter to surrounding fluid pressure within the reservoir, the advantageous operation and results may nevertheless be attained when only a part of the lip may be exposed to the reservoir due to limitations in design in certain cases. For example, one-half to twothirds of the lip may be thus exposed while the remainder may be exposed only after the piston valve has been displaced, and yet attain desirable operating results.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.

I claim as my invention:

1. In a pneumatic driving machine, a head portion, a handle portion projecting rearwardly from the head portion, said head portion having therein a compressed fluid reservoir within which a cylinder is provided with an end opening arranged for exposure within the reservoir, a driving member actuating piston reciprocably operable in said cylinder, at driving member carried by said piston, means normally urging the piston toward said cylinder end, and means normally closing said cylinder end but shiftable toward open position for opening the cylinder to full fluid pressure within the reservoir for driving the piston and said member in a driving stroke thereof, said handle portion providing therein a substantial volume supplementary or auxiliary reservoir space communicating freely with said reservoir.

2. In a pneumatically operated driving machine, a unit including a casing structure providing a head portion and a handle portion extending therefrom, said head and handle portions providing a large volume compressed fluid reservoir, a piston and cylinder assembly having direct opening of the cylinder into said reservoir in the head portion of the reservoir for exposure of the piston to fluid pressure within the reservoir to drive the piston in a driving stroke, means for normally closing said cylinder from the reservoir and including pneumatic control means utilizing fluid pressure metered from the reservoir, said cylinder closing means being openable by pressure within the reservoir incident to bleeding off the operating metered fluid pressure therefrom, and means for supplying fluid under constant pressure to the reservoir including a restrictor orifice proportional to said metered fluid pressure means for sufficiently throttling initial surge of compressed fluid into the reservoir to avoid blowing ofi of said cylinder closing means until metered fluid pressure has developed for holding said closing means in its closing rela tion.

3. In a pneumatic driving device, a casing structure including a head portion and a handle portion extending therefrom with a pressure fluid reservoir of substantial volume in the head portion, a cylinder open at one end to said reservoir and having a piston therein normally biased toward the open end but operable in a driving stroke away from said open end by the fluid pressure within said reservoir, a closure valve member normally closing said open end of the cylinder, pneumatic means for controlling said closure valve including a control valve having a manual operating element exposed on the casing structure adjacent juncture of the head and handle portions and including an exposed manually operable element, and safety flange means projecting from the casing structure adjacent to said manually operable element to avoid accidental actuation of said element.

4. In a pneumatic driving device, a casing structure including a head portion and a handle portion extending therefrom with a pressure fluid reservoir of substantial volume in the head portion, a cylinder open at one end to said reservoir and having a piston therein normally biased toward the open end but operable in a driving stroke away from said open end by the fluid pressure within said reservoir, a closure valve member normally closing said open end of the cylinder, and pneumatic means for controlling said closure valve including a control valve having a manual operating element exposed on the casing structure adjacent the juncture of the head and handle portions.

5. In a pneumatic driving device including a casing structure having a handle with a head portion on the forward end thereof and with a pressure fluid reservoir of substantial volume in said head portion and at least the adjacent portion of the handle, said head portion having therein a cylinder barrel structure opening freely into said reservoir and having a driving piston reciprocable therein and normally biased toward the open end of the cylinder, said head portion having spaced beyond said open end of the cylinder a control valve cylinder within which is reciprocably movable a control valve piston engageable closingly with said cylinder end for blocking ingress of pressure fluid from the reservoir into said cylinder barrel structure, said valve piston being marginally exposed to the pressure fluid within the reservoir about said cylinder end, means providing a passage from said reservoir to said control valve cylinder on the opposite side of said valve piston from said exposed margin to impress upon said opposite side of the valve piston the force of pressure fluid from the reservoir to offset the force of the pressure fluid on said exposed margin and thereby bias the valve piston into closing relation to said cylinder end, and means for selectively bleeding off the fluid from said control valve cylinder for unbalancing the valve piston to be opened by the force of the pressure fluid on said exposed margin to thereby expose said cylinder end to the full force of pressure fluid in the reservoir to drive said driving piston in opposition to its bias.

6. A driving machine as defined in claim 5 wherein said bleeding means includes a normally closed valve and an exhaust passage to atmosphere adjacent the upper portion of the juncture of the handle and head portion and provided with a manually operable actuating member exposed outside of the casing for selective manipulation of said fluid bleeding valve.

7. In a pneumatic driving machine, a head portion having therein a compressed pneumatic fluid reservoir and a cylinder provided with an end opening arranged for exposure within the reservoir, means affording a compressed fiuid supply under substantially constant pressure in said reservoir, a driving member actuating piston reciprocably operable in said cylinder,

a driving member carried by said piston, the piston being biased toward said cylinder end, pneumatically responsive means normally effecting closing of said cylinder end but shiftable for opening the cylinder end to the pneumatic pressure within the reservoir for driving the piston and said member in a driving stroke thereof, means providing a fluid passage eifecting communication between said reservoir and said pneumatically responsive means,

said passage having a bleed off therefrom, and a valve operable to close said bleed off and to open said bleed off.

8. In a driving machine includin a pneumatic driving device,

a casing structure inciudin a head portiond and a portion extending therefrom with a pressure fluid reservoir of substantial volume in the head portion, a cylinder open at one end to said reservoir and having a piston therein normally biased toward the open end but operable in a driving stroke away from l 1 said open end by the fluid pressure within said reservoir, a closure valve member normally closing said open end of the cylinder,

and pneumatic means for controlling said closure valve including both a substantially unrestricted passage from said extending portion into said head portion for conveying fluid pressure from the reservoir to said head portion -for biasing said closure valve member into closing position and a manually cngageable control valve operable externally of said head portion and projecting portion and normally closing a bleedoff from said passage but movable to open said bleedofl to relieve said closure valve from the closingly biasing eliect of the pressure fluid to permit said closure valve to open and expose the cylinder and the piston therein to the pressure fluid.

9. A pneumatically operated fastener driving device comprising:

a housing having a head portion defining a first chamber and a cylinder having an open end in communication with said first chamber,

said housing also having a hollow handle portion extending rearwardly from said head portion and providing a second chamber in continuous and unrestricted communication With said first chamber, said first and second chambers providing a reservoir of compressed air for operating said fastener driving device;

a piston slidably mounted in said cylinder;

means for biasing said piston toward the open end of said cylinder;

pneumatic control valve means including a piston portion movably mounted in said head portion and a valve portion movable into and out of closing relation with the open end of said cylinder,

a lower surface of said piston portion being exposed to the compressed air in said reservoir which biases said valve portion away from said closing relation with said open end of said cylinder;

a passageway formed in said housing and extending rearwar ly from an upper portion of said head portion and communicating with said reservoir at a position adjacent the juncture of said head portion and said handle portion,

said passageway normally supplying compressed air from said reservoir to said upper portion of said head portion to act on the upper surface of said piston portion to bias said valve portion into closing relation with said open end;

resilient means positioned in said upper portion of said head portion and acting on said pneumatic control valve means to bias said valve portion into closing relation with said open end;

and a control valve assembly mounted on said housing adjacent said juncture of the head and handle portions of said housing,

said control valve assembly including a movable valve element and a valve operating element extending out of said housing and operable to conrol the movement of said valve element, said control valve assembly also including an exhaust passage and said movable valve element movably closing said exhaust passage but being movable by said valve operating element to a position placing said passageway in communication with said exhaust passage so that compressed air in said reservoir acts on said piston portion to move said valve portion out of closing relation with said open end,

said movable element also being movable to a position closing said passageway from communication with said exhaust passage so that said resilient means and the compressed air delivered by said passageway and into said upper portion 12 of said head portion act on said pneumatic control valve means to move said valve portion into said closing relation with said open end.

10. In a pneumatic driving machine,

a head portion having therein a compressed pneumatic fluid reservoir and a cylinder provided with an end opening arranged for exposure within the reservoir, a driving member actuating piston reciprocably 0perable in said cylinder,

at driving member carried by said piston, the piston being biased toward said cylinder end, pneumatically responsive means including a member normally closing said cylinder and but shiftable for opening the cylinder end to the pneumatic pressure within the reservoir for driving the piston and said member in a driving stroke thereof,

means providing a pneumatic fluid passage communicating between said reservoir and said pneumatically responsive means for operation of said member by pneumatic fluid from the reservoir,

and valve means operative to control imposing of pneumatic fluid force on said pneumatically responsive means through said passage.

.11. in a pneumatic driving machine,

a head portion,

said head portion having therein a pressure fluid reservoir and a cylinder provided with an end opening arranged for exposure within the reservoir, means for supplying said reservoir with air under substantially constant pressure and from which pressure the reservoir is not disconnected throughout the operation of the machine,

a driving piston reciprocably operable in said cylinder, the piston being biased toward said cylinder end, and means normally closing said cylinder end, said closing means and said cylinder end being relatively separable for opening the cylinder end to fluid pressure within the reservoir for driving the piston in a driving stroke thereof.

12. In a pneumatic driving machine, a head portion,

a handle portion projecting rearwardly from the head portion,

said head portion having therein a compressed fluid reservoir and a cylinder provided with an end opening arranged for exposure within the reservoir, a driving member actuating piston reciprocably operable in said cylinder,

at driving member carried by said piston, means normally urging the piston toward said cylinder end,

and means normally closing said cylinder end but shiftable toward open position or opening the cylinder to full fluid pressure within the reservoir for driving the piston and said member in a driving stroke thereor", and means for connecting to the reservoir a direct and continuous source of compressed fluid under pressure.

13. In a fastener driving machine, a driving member,

a pneumatic piston for actuating said driving member,

a cylinder reciprocably housing said piston,

means providing a reservoir of fluid under substantially constant pressure to which said cylinder is exposed,

and means for closing the cylinder but operable to open the cylinder to the full eflect of the fluid pressure within the reservoir for driving the piston in a fastener driving stroke.

14. In a pneumatic driving mechanism,

means defining a reservoir,

a cylinder having an open end exposed within the reservoir,

a piston reciprocable in the cylinder ond norrnally iased toward said open end of the cylinder,

a closure valve piston nori'r ally biased toward closing relation to the open end of the cylinder,

said piston valve having a readily replaceable flexible valve disk in direct engagement with the open end of the cylinder and adapted to cling to the valve piston when the valve piston is backed off from the open end of the cylinder so as to assure substantial air gap between the piston valve and the open end of the cylinder for dumping of air under full pressure within the reservoir into the cylinder incident to said backing off, and means for controlling closing said backing oft action of the valve piston.

15. In a pneumatic driving device, a casing structure having therein a pressure fluid reservoir of substantial volume with a cylinder having its end exposed within the reservoir spaced from an opening into the reservoir,

:a piston reciprocable in said cylinder and normally biased toward said end of the cylinder,

a closure member over said opening into the reservoir and providing an exhaust passage structure arranged to communicate with said cylinder end,

and control means including pressure fluid responsive structure and a controlled passageway from the reservoir to supply pressure fluid thereto,

said control means being active to close said cylinder end and to control exhaust through said passage and operable to open said cylinder end .md simultaneously close said exhaust passage for driving said piston by pressure fluid then entering the cylinder end from the reservoir to impel the piston in opposition to its bias,

said control means being operable following driving stroke of the piston to close said cylinder end and open said exhaust passage for return of the piston as effected by said piston bias.

16. A fastener driving apparatus comprising a housing defining a chamber,

means for supplying said chamber continuously with compressed air,

a cylinder mounted in said housing and having its end exposed to said chamber,

fastener driving means including a piston slidably mounted in said cylinder,

a valve element in said chamber movable into and out of engagement with said cylinder end to control the admission of said compressed air from said chamber into said cylinder,

a member including a passageway secured to said valve element and movably mounted on said housing, means for moving said valve element and said member relative to said cylinder,

and means including said passageway for selectively venting said cylinder.

17. In a fastener-applying machine, a casing having a main pressure-chamber therein, means for continuously supplying fluid-pressure to said chamber,

a cylinder in said casing having an ingress opening therein,

a piston slidable in said cylinder, a fastener-driver connected to said piston for actuation thereby,

a diaphragm valve-closure engageable with the ingress opening in said cylinder to close it against ingress of pressure,

said valve-closure disposed to divide the interior of the casing to form an auxiliary pressure-chamber at the end of said main chamber and said valve-closure having a greater area of its surface exposed to the pressure in the auxiliary chamber than the area of its surface exposed to the pressure in the main chamber to normally maintain it closed against the ingress opening in the cylinder,

and means for exhausting the pressure from the auxiliary chamber to release the valve-closure for admitting pressure to the cylinder to operate the piston for actuating the fastener-driver.

18. In a pneumatic driving machine, a head portion,

a handle portion projecting rearwardly from the head portion,

said head portion having therein a compressed fluid reservoir within which a cylinder is provided with an end opening arranged for exposure within the reservoir, means for supplying said reservoir with air under substantiallyconstant pressure and from which pressure the reservoir is not disconnected throughout the operation of the machine,

a driving member actuating piston recip-rocably operable in said cylinder,

at driving member carried by said piston, means normally urging the piston toward said cylinder end, and means normally closing said cylinder end but shiftable away from said cylinder end toward an open position when the cylinder is opened to full fluid pressure within the reservoir for driving the piston and said member in a driving stroke thereof,

said cylinder closure means including exhaust duct structure operable for evacuating the cylinder above the piston in the closed relationship of said closing means to the cylinder.

References Cited in the file of this patent UNITED STATES PATENTS 562,518 Ferguson June 23, 1896 1,164,889 Tessmer Dec. 21, 1915 1,594,232 Zimmermann July 27, 1926 1,832,152 Stewart Nov. 17, 1931 2,412,620 Kipp Dec. 17, 1946 2,542,305 Brinen et al. Feb. 20, 1951 2,548,736 Morberg Apr. 10, 1951 2,593,231 Wandel Apr. 15, 1952 2,671,214 Iuilfs Mar. 9, 1954 2,677,933 Hopkinson May 11, 1954 2,713,165 Campbell July 19, 1955 2,720,864 Smith Oct. 18, 1955 2,729,198 Faccou Jan. 3, 1956

Claims

1. IN A PNEUMATIC DRIVING MACHINE, A HEAD PORTION, A HANDLE PORTION PROJECTING REARWARDLY FROM THE HEAD PORTION, SAID HEAD PORTION HAVING THEREIN A COMPRESSED FLUID RESERVOIR WITHIN WHICH A CYLINDER IS PROVIDED WITH AN END OPENING ARRANGED FOR EXPOSURE WITHIN THE RESERVOIR, A DRIVING MEMBER ACTUATING PISTON RECIPROCABLY OPERABLE IN SAID CYLINDER, A DRIVING MEMBER CARRIED BY SAID PISTON, MEANS NORMALLY URGING THE PISTON TOWARD SAID CYLINDER END, AND MEANS NORMALLY CLOSING SAID CYLINDER END BUT SHIFTABLE TOWARD OPEN POSITION FOR OPENING THE CYLINDER TO FULL FLUID PRESSURE WITHIN THE RESERVOIR FOR DRIVING THE PISTON AND SAID MEMBER IN DRIVING STROKE THEREOF, SAID HANDLE PORTION PROVIDING THEREIN A SUBSTANTIAL VOLUME SUPPLEMENTARY OR AUXILIARY RESERVOIR SPACE COMMUNICATING FREELY WITH SAID RESERVOIR.