US2807021A

US2807021A - Fluid motors of the percussive type

Info

Publication number: US2807021A
Application number: US487317A
Authority: US
Inventors: Fred F Chellis
Original assignee: United Shoe Machinery Corp
Current assignee: United Shoe Machinery Corp
Priority date: 1955-02-10
Filing date: 1955-02-10
Publication date: 1957-09-24
Anticipated expiration: 1974-09-24

Description

Sept. 24, 1957 F. F. CHELLIS 2,807,021

FLUID MOTORS OF THE PERCUSSIVE TYPE 7 Filed Feb. 10, 1955' 4 3 Sheets-Sheet, 1

[nus-afar Fred E'Chel/is Sept. 24, 195

Filed Feb. 10, 1955 7 F. F. C ELLIS 2,807,021

FLUID MOTORS OF THE PERCUSSIVE TYPE 5 Sheets-Sheet 3 fm/cnlor United States Patent FLUID MOTORS OFTHE PERCUSSIVE TYPE Fred F. Chellis, Manchester, Mass, assignor to United Shoe Machinery Corporation, Flemington, N. J., a corporation of New Jersey Application February 10, 1955, Serial No. 487,317

22 Claims. (Cl. 1101) The present invention relates to fluid motors of the vented to atmosphere allowing the valve itself to be opened by the pressure in the high pressure chamber nicates with the low pressure chamber to provide a large percussive type and more particularly to pneumatic motors of the type used for driving fasteners by impact. However, it is to be understood that various features of the present invention are not thus limited in their utility.

Percussive type fluid motors are basically very simple and comprise a cylinder housing a piston which is moved therein by fluid pressure. The construction of such motors becomes more complicated when they are designed for maximum efficiency, obtaining maximum utilization of the fluid pressure and, in the case of pneumatic motors, minimizing fluid consumption. In the field of pneumatic, portable or hand-held fastener inserting devices or guns, efficient use of the operating fluid is of particular importance. It is of course desirable that the air motors used in such guns be of minimum weight to minimize operator fatigue and that they require a minimum of effort to operate. Preferably, such guns should be designed to drive nails and other types of fasteners to the required depth by a single blow. Thus the air motor used to drive the fastener should have percussive action and be readily adapted to single cycle operation. Furthermore, since various size nails may be driven by one gun, a serious problem of shock absorption may arise if a gun is used to drive nails which are substantially smaller than the maximum size for which the gun was designed.

It is therefore a principal object of the present invention to provide an improved fluid motor of the percussive type.

A further object of the invention is to provide an improved pneumatic motor having means for minimizing the amount of air needed for its operation.

Yet another object of the present invention is to provide an improved fastener inserting device of light weight construction which is easy to actuate and which may be operated with a minimum of fluid consumption.

My invention is herein disclosed in a novel fastener inserting gun embodiment.

In accordance with the various features of the present invention there is provided a fluid motor of the reciproeating type wherein pressurized fluid is introduced into chambers on either side of a piston with the pressure in one chamber being lower than the pressure in the other chamber and the fluid in the higher pressure chamber is vented to allow the piston to be driven by the lower pressure fluid. Preferably a single air supply line is provided and a pressure regulating valve mounted at the entrance 7 to the low pressure chamber controls the pressure therein. Thus the fluid in the low pressure chamber need not be vented as the piston is returned in each cycle by repressurizing the high pressure chamber. Provision is made for adjusting the pressure regulating valve so that the energy imparted to the piston may be matched to the particular requirements thereof.

An internal control valve seals off one end of the high pressure chamber from venting ports. Fluidpressure normally maintains this valve in its sealing positron and, when the piston is to be driven by the low pressure fluid, is

storage capacity of. pressurized fluid while at the same time protecting the air motor from injury.

A pilot valve may be operatively connected to the nose piece of the inserting gun for controlling the pressurized fluid which maintains the control valve inits sealing position.

Yieldably mounted locking means are provided for preventing fasteners which are automatically delivered to the inserting gun from being inadvertently discharged therefrom.

The above and other features of the invention including various novel details of construction and combination of parts will now be more particularly described with reference to the accompanying drawings. and pointed out in the claims.

In the drawings,

Fig. 1 is a view showing the general outline of the fastener inserting gun of the present invention;

Fig. 2 is a schematic view of the inserting gun associated with automatic means for delivering fasteners thereto;

Fig. 3 is a crosssection of the gun shown in Fig. 1 on an enlarged scale with the driver in its inactive position;

Fig. 4 is a view similar to Fig. 3 with certain portions omitted and with the driver in its released position;

Fig. 4a is a view of the nose piece of the gun showing the relation of certain parts immediately after the gun has been removed from a workpiece;

Fig. 5 is a section taken on the line VV inFig. 3;

Fig. 6 is a section taken on the line VIVI in Fig. 5;

Fig. 7 is a section taken on the line VII-VII in Fig. 3;

Fig. 8 is a section taken on the line VIIL-VIII in Fig. 3; and

Fig. 9 is a section taken on the line IX-IX in Fig. 3.

For simplicity certain specific terms will. be used in the following description which are not intended in any way to limit the breadth of the invention. For example, certain aspects of the invention are applicable to fluid motors generally although an air motor is described for operating the inserting gun. While the inserting gun itself is adaptable to drive all types of fasteners which are driven by an impact blow reference is made only to nails. Other terms are used in the following description which are likewise not intended to place any limitation on the breadth of the invention as will be obvious from a reading of the claims.

Referring now to Fig. 1 an inserting gun 20 is shown in outline form. This type of gun is adapted for portable operation to insert nails. A handle 22 enables an operator readily to position the gun 20 and drive nails into workpieces by pressing its nose piece 24 against a workpiece. This'type of gun is preferably used in combination with means for automatically delivering one nail at a time to the inserting gun in response to'the operation of the gun. Nail delivering means are indicated schematically in Fig. 2 and will be described in detail below. The inserting gun 20 is provided with an air supply line 26, a nail delivery tube 28 and a signal line 30. The

lines

26 and 30 and the tube 28 are formed of metal tubing for the short distance along the length of the gun 20 with one end of each being mounted in a plate 32. Beyond the gun 20 the

lines

26 and 30 and the tube 28 are formed of flexible tubing, preferably of some synthetic rubber-like material, which continue to a remote W. Air may then flow from the bore 80 (Figs. 2

operated simply by pressing the nose piece 24 of the gun against workpieces which are to be fastened.

The inserting gun 20 is of extremely light and rugged construction and provides a maximum usage of the energy of the compressed air all of which will become more apparent from a detailed study of the construction shown in Fig. 3 and various other detail views. The gun 20' is provided with an outer casing 38 to which the handle 22 is attached by a metal band 40 (Fig. 1). Within the casing 38 is a concentric cylinder 42 in which a driver piston is slidable. A driver 46 is secured to the piston 44 by a nut 48 and extends downwardly within the cylinder 42 toward the nose piece 24. It will be appreciated that the driver 46 is in effect a piston rod and therefore is equivalent to such should it be desired to utilizethe air motor of the present invention in any other application. The driver 46 and its associated piston 44 are shown in their upper or inactive positions in Fig. '3 in readiness to drive a nail positioned in the nose piece 24. This inactive position of the inserting gun 20 will first-be described.

A plug 50 is threaded into the lower end of the casing 38 and has projections 51 which space it apart from the lower end of the cylinder 42 (Fig. 9). Another plug 53 is threaded into the upper end of the casing 38, the plug 52 heing'provided with a recess 54 which provides means for positively locking the upper end of the cylinder 42 in concentric relation with thecasing 38. An internal control valve 56 seals off the lower end of the cylinder 42 and is provided with an opening 58 through which the driver 46 may pass. For convenience the space within the cylinder 42 beneath the driver piston 44 will be referred to as the lower chamber 60 of the inserting gun I 2. and the space within the cylinder 42 above the driver piston 44 will be referred to as the upper chamber 62 of the inserting gun as seen in Fig. 3. The annular space between the cylinder 42 and the outer casing 38 forms an accumulator 64 for compressed air which is connected to the upper chamber 62 through a series of holes 66.

To locate the piston 44 in its upper or inactive position 'shown in Fig. 3, compressed air is supplied to the lower chamber 60 in the following manner. The air supply line 26 has a collar 68 (Fig. secured to its lower which is fastened to the plug 50 by a specially formed screw 70. Air enters the gun 20 through the line 26, Ms around a reduced portion 72 of the screw 70, through-radial passages 74, an axial passage 76, and a passageway 78 formed in the plug 50 to a two diameter bar-e80.

A ball check 82 is provided within the axial y 76 to prevent free flow of air from the insert to the line 26 for reasons which will hereinafter and 8) through an annular chamber 84 and holes 86 to the lower side of the control valve 56. Air then flows 11101181111116 opening 58 between a packing 88 and the drive to the lower chamber 60. The lower chamber 0 is thus maintained at the same pressure as the supply line .26. The. control valve 56 is maintained in its upper position sealing off the lower end of the cylinder 42 due to the fact that there is a greater area on its lower side subjected to line pressure than upon its upper surface.

s upper chamber 62 of the gun 20 is maintained at a pressure below line pressure in the supply line 26 by means of the following mechanism. Referring to Fig. 8 it can be seen that the supply line 26 communicates with a passageway 90 formed in the plate 32. The passageway 90 in turn communicates with an annular chamber 92 surrounding an extension of the plug 52 and through radial passageways 94 formed therein to a pressure regulating valve 96. The valve 96 is normally main tained in its closed position by a compression spring 98 which is seated in a recess formed in a screw cap 100. The screw cap 100 is threaded into the plug 52 and serves also to clamp the plate 32 in its proper position with respect to the various elements of the inserting gun. The regulating valve 96 controls flow of air through a passageway 102 to the upper chamber 62. The stem 194 of the valve 96 is fluted so that when the valve is raised against the action of the spring 98 air passes through the passageway 102 pressurizing the upper chamber 62 and the accumulator 64.

When the air supply line 26 is first connected to a source of compressed air, the lower chamber 60 of the inserting gun 20 first becomes pressurized by flow of air through the various passageways, as explained above, moving the piston 44 in an upward direction thereby opening the pressure regulating valve 96 and admitting compressed air to the upper chamber 62 and the accumulator 64. As the pressure in the upper chamber 62 increases, the force of the spring 98 will displace the piston 44 downwardly closing the valve 96 before the pressure in the chamber 62 reaches line pressure. It will be noted that the area of the upper surface of the piston 44 is greater than that of the lower surface due to the presence of the driver 46. This difference in area establishes the minimum pressure differential which must exist between the

chambers

60, 62. With this arrangement the driver piston 44 and the driver 46 are maintained in their inactive positions ready to drive a nail, as shown in Figs. 2 and 3. When compressed air is vented from the lower chamber 60, in a manner to be described presently, the driver piston and the driver are driven downwardly to the positions shown in Pig. 4 by the compressed air in the upper chamber 62 and in the accumulator 64. A screw 195 threaded into the screw cap 108 is provided for adjusting the force exerted by the pressure regulating valve spring 98. As was just described the pressure in the upper chamber 62 and the accumulator 64 is dependent upon the spring load; thus this pressure may be varied by adjustment of the screw 105. A lock out 107 may be provided to maintain the screw in proper adjustment. In this manner the energy imparted to the driver piston 44 and the driver 46 may be matched to the type and size of nail being driven thereby minimizing the shock imparted to the various elements of the gun.

When air is reintroduced into the lower chamber 60 after a nail is driven, the driver piston 44 is returned upwardly, recompressing the air in the upper chamber 62 and in the accumulator 64. At this time the driver piston 44 will not necessarily assume its uppermost position because the pressure in the upper chamber 62 is only slightly below line pressure, this condition being illustrated in Fig. 3. During each cycle of operation of the driver piston 44, air may leak from the upper chamber 62 so that after several cycles of operation the pressure therein will become reduced sufiiciently to permit the driver piston 44 to be forced upwardly until the spring 98 is again overcome and air flows through the passageway 102 to return the pressure in the upper chamber 62 to the desired value. This arrangement effects a great economy of air in that only one chamber of the air motor need be exhausted in the operation of the gun while, at the same time it is not necessary to provide auxiliary means for the return stroke of the driver piston 44.

Venting of the lower chamber 60 to actuate the driver piston 44 and the driver 46 is initiated by the relative displacement of the gun and a pilot valve 106 one end of which rides in the smaller diameter portion of the bore 80 and the other end of which rides in the larger diameter portion of the bore 80 and in a concentric bore 81 of equal diameter formed in a nose piece bracket 108. The nose piece bracket 108 is secured to the plug 50 by screws 110. It will be noted that the lower spool of the pilot valve 106 is of greater diameter than the upper spool. Therefore, air entering through the passageway 78 (Figs. 3 and normally maintains thepil'ot valve 106 in its lowermost position, wherein the larger diameter spool is in the concentric bore 81, and in which air may pass to the lower chamber'60 in the manner described above.

As was pointed out above, the inserting gun 20 is operated by pressing the nose piece 24 against a workpiece which effects relative displacement of the gun and the pilot valve 106. The nose piece and the pilot valve 106 are connected in the following manner: A hollow rod 112 extends from the lower end of the pilot valve 106 to the lower end of the bracket 108 where a springfingered quill 114 is provided to position nails in proper alinement with the driver 46. A quill retaining sleeve 116 extends beyond the rod 112. The sleeve 116 may be secured to the rod 112 by spring clips 119 as seen in Fig. 7 though a positive fastening is not essential. Two screws 118 extend from either side of the sleeve 116 and enter holes formed in the nose piece 24. It will be understood that as .the gun is initially pressed toward the workpiece to drive a nail the entire gun including the casing 38 and the nose piece 24 moves. Upon contacting the workpiece, the motion of the nose piece 24, the rod 112 and the pilot valve 106 ceases but the casing 38 and the remaining mechanism of the gun continue toward the workpiece a short distance. During this time the gun is actually moving relative to the stationary nose piece but for the sake of a simpler description of operation, as will becomemore apparent hereinafter, the nose piece 24, the rod 112, pilot valve 106, and the mechanism fixed thereto will be described as moving upwardly relative to the gun. Thus when the gun 20 is pressed against a workpiece, the nose piece 24 acting through the screws 118, the sleeve 116, and the rod 112 effects relative displacement of the gun and pilot valve 106. The compressed air acting on the lower side of the control valve 56 vents to atmosphere through a hole 120 in the bracket 108 as soon as the larger diameter spool of the pilot valve 106 is positioned above the annular chamber 84 as is seen in Fig. 4, the air passing through the holes 86, the annular chamber 84, around a reduced area 121 formed on the rod 112 and out hole 120. When the lower side of the control valve 56 is thus vented to atmosphere, the pressure in the lower chamber 60 forces the control valve 56 downwardly at a rate which is far greater than the corresponding control valve could be opened by hand operation and with greater consistency from one cycle of operation to another. Displacement of the control valve 56 vents the lower chamber 60 to atmosphere through a series of radial passageways 122 (Fig. 9) which hitherto had been covered by the control valve. When the inserting gun 20 is removed from a workpiece, the pilot valve 106 again returns to the position in Fig. 3 due to the greater air pressure force which is at all times effective upon its larger diameter spool.

The following provisions are made for the automatic delivery of nails to the quill 114. The lower end of the delivery tube 28 is secured to the bracket 108 by a strap 124 and screws 126 (Fig. 1). An opening 128 is formed in the hollow rod 112 so that nails pass along the delivery tube 28 through the opening 128 and into the quill 114. Since these nails are delivered, preferably by a blast of compressed air, it is necessary that means be provided to prevent them from being blown out of the nose piece when they are delivered. Therefore, a quill locking sleeve 130 is provided to retain a nail within the quill. The quill locking sleeve 130 rides within a nose piece mounting sleeve 132 which is secured to the br cket 108 by a pin 134 and a spring clip 136. The

sleeves

130 and 132 are provided with elongated slots 138 within the screws 118 ride and which thereby limit the motion of the nose piece 24. It will be noted that the quill locking sleeve 130 has an internal ledge 130 which prevents outward displacement of the spring fingers of the quill 114 when the gun is in its inactive or ready position shown in Fig. 3.

When the gun 20 is pressed against the workpiece, .there is' relative movement between the nose piece 24 and the quill 114 with respect to the quill locking sleeve 130. The lowermost end of the quill 114 is tapered and it is thus possible for the spring fingers to be displaced outwardly within the locking sleeve as the driver 46 drives a nail therefrom as is illustrated in Fig. 4. When the inserting gun 20 is removed from a workpiece, there is relative movement of the pilot valve and the parts connecting it with the nose piece 24 with respect to the gun to admit air to the lower chamber 60 and initiate the return of the piston 44 and the driver 46 to their inactive positions, as explained above. The quill locking sleeve 130 must move at this time with the nose piece 24 because the driver 46 has not moved above the ends of the fingers of the quill 1 14 so that they are held in their outwardly displaced condition. It is thus necessary to provide a compression spring 140 which allows the quill locking sleeve 130 to move independently of the nose piece mounting sleeve 132 and then return it to the position seen in Fig. 3 wherein the driver is shown elevated. The intermediate position of these parts is shown in Fig. 4a. As soon as the driver is above the quill 114, the spring 140 will return the locking sleeve 130 to its normal position shown in Fig. 3.

As was mentioned above, the present device is particularly adapted for use with automatic means for delivering nails. It is therefore necessary to provide signalling means for actuating the operation of the delivering means. A passageway 142 (Figs. 3 and 6) extending from the bore 80 is provided for that purpose. The passageway 142 extends to an axial passage 144 and radial passageways 146 formed in a screw 148. The screw 148 is threaded into the plug 50 and clamps a sleeve 150 secured to the lower end of the signal line 30 in a manner similar to the assemblage at the lower end of the air supply line 26. It will be noted that when the pilot valve 106 is in its upper position (Fig. 4) the passageway 142 is in direct communication with the air supply line 26 through the passageway 78. Thus each time the pilot valve 106 is in position to actuate the inserting gun 20 the signal line 30 becomes pressurized at full line pressure.

There are many systems for automatic delivery of nails. One such arrangement is shown in Fig. 2 in schematic form. The details of this system are fully described in application for United States Letters Patent Serial No. 427,022, filed May 3, 1954, in the name of Donald B. McIlvin. Particularly this system comprises a hopper 152 in which nails are stored, a lift slide 154 for delivering nails to a raceway 156, and a separating segment 158 for bringing one nail at a time from the lower end of the raceway to a point in alinement with .the delivery tube 28. An air motor 160 having a piston 161 is provided for actuating the lift slide 154 and the separating segment 158. A base 162 extends from the main control valve 36, which has a piston 163 slidable therein, and interposed in the line 162 is a time delay valve 164 having a piston 164 to provide a controlled blast of air for delivering each nail through the delivery tube 28 to the inserting gun 20. A pair of lines 165 and 165' also extend from the control valve 36 to rightand left-hand sides of the air motor 160 respectively. It will be noted that the signal line 30 extends to the control valve 36. Thus when the signal line 30 is pressurized the piston 163 within the control valve is displaced from a first or righthand to a second or left-hand position. This causes the iston 161 of the air motor 160 to be moved to the left by an increase in pressure in the line 165 and a decrease in pressure in the line 165, causing the lift slide 154 to deliver nails to the raceway 156 and moving the separating segment in a counterclockwise direction so thata slot 166 formed therein is in alinement with the raceway. The pressure in the line 165 causes the piston 164 of the control valve 164 to: be displaced from the position shown in Fig. 2 to its right-hand position. However, it will be noted that the control valve 36 blocks passage of pressurizedair through the line 162 at this time and vents the line 162 to atmosphere. When the signal line is depressurized after the gun 20 is removed from a workpiece, the piston 163 of the control valve 36 returns to its first or right-hand position. The piston 161 of the air motor 16. moves to its right-hand position as seen in Fig. 2 thereby causing the lift slide 154 to move downwardly and the separating segment 158 to move in a clockwise direction whereby, the lowermost nail is carried by the slot 166 to a point in alinement with the delivery tube 28. Air then flows through the line 162 to carry the separated nail through the delivery tube 28 so that the nail N will become positioned within the quill 114 as is seen in Fig. 3. The time delay valve 164 is adjusted so that only a short blast of air travels through the line 162.

In the present construction specific mention of the various seals and packings which are used in the inserting gun 20 have been omitted. However, to avoid confusion the various seals will now be described. All seals which are of circular cross section are annular rings of resilient material commonly known as rings. 0 rings 168 provide static seals between the nut 100, the plate 32 and the plug 52. An 0 ring 170 provides a seating seal for the pressure regulating valve 96. An 0 ring 172 provides a static seal between the plug 52 and the casing 38. An 0 ring 174 provides a static seal between the casing 38 and the lower end of the cylinder 42. An 0 ring 176 provides a static seal between the casing 38 and the plug 50. An 0 ring 178 is used as a packing for the driver piston 44. An 0 ring 180 is used to provide sealing means for the control valve 56 in sealing off the lower end of the cylinder 42. A standard packing 182 is pro vided for the control valve 56. An 0 ring 184 provides a seal between the bore 80 and the driver 46. 0 rings 1, 188 are provided as packings for the pilot valve 106. O ringsl90, 192 provide seals between the

screws

70, 148 and the

sleeves

68 and 150 respectively. The packing 88 inside the control valve 56 has been mentioned in the description above.

In the operation of the inserting gun 20 the parts are normally in their inactive or ready positions shown in Figs. 2 and 3. The lower chamber 60 is at full line pressure while the upper chamber 62 and the accumulator 64 are at a pressure below line pressure. The control valve 56 is maintained in its upper position by pressurized air from line 26 to reduced portion 72 of screw 70 (Fig. 5) then through radial passages 74, axial passages 76, '78 to bore 80. (Figs. 2 and 3), to annular chamber 84 (Fig. 3),

holes 86, to the lower face of control valve 56 sealing off the lower chamber 60 due to the fact that there is a greater area on its lower face of the control valve 56 exposed to full line pressure. The pilot valve 106 is maintained in its lower position due to the greater diameter of its lower spool. A nail N is positioned in the quill 114 in readiness to be driven by the driver 46. The nail delivery parts are in their respective positions shown in Fig. 2.

To drive the nail the operator grasps the handle 22 on the casing 38 and moves the gun toward the workpiece until the nose piece 24 strikes the workpiece which prohibits its further movement and that of the spool valve 106. A small amount of continued movement of the casing 38 toward the workpiece causes the two diameter bore 80 to fully envelop the then stationary spool valve 106 whereupon the pressurized air on the lower side of the control valve 56 is vented to atmosphere through the holes 86, the annular chamber 84 and the hole 120. The pressure in the lower chamber 60 is vented to atmosphere through the then uncovered passageways 122 allowing the piston 44 and the driver 46 to be driven with a percussive force away from the inactive position and toward a forcedelivering positionby the air compressed within the upper chamber 62 and in the accumulator 64 to drive the nail. The stroke of the piston 44 hitting against the control valve 56 is absorbed by a rubber bumper 194. This shock force, however, is minimized by maintaining the pressure in the upper chamber at a point Where the energy imparted to the driver piston 44 is just sufficient to drive the particular type and size of nail. The driving force is all the more effective because the control valve 56 is opened by the air pressure in the lower chamber 6%). This opening movement is more rapid and consistent from operation to operation than could be provided by any manual movement. In this way a minimum back pressure must be overcome in propelling the driver piston it should be noted that air cannot pass outwardly through the packing 88 so that all of the energy of the air in the lower chamber 60 is effective in opening the valve 56.

The relative position of the spool valve 106 within the two diameter bore 8%) places the passageways 73 and 142 in direct communicaiton and the signal line 30 is pressurized at full line pressure thereby providing effective means for actuating the control valve 36 which in turn initiates the cycle for delivering a further nail to the quill as soon as the gun is removed from the workpiece.

As seen in Fig. 2 the pressure in the signal line 30 moves the piston 163 to the left, the line 165 being thus pressurized and lines 162 and 165' being vented to atmosphere. The reversal of forces on the piston 161 causes it to move to the left actuating the lift slide 154 to deliver nails to the raceway 156, and moving the separating segment 158 to a fastener receiving position adjacent the raceway. The pressure in the line 165 displaces the piston 164' of the time delay valve 164 to the right removing the restriction in the line 162 but since the line 162 is vented to atmosphere through the valve 36 no pressurized air flows to the delivery tube 28 at this time.

When the gun 213 is removed from the workpiece the pilot valve Hi6 and the two diameter bore assume their original positions relative to each other due to the pressure in the line 26 exerting a greater force on the larger diameter lower spool of the valve 106 than on the smaller. Pressurized air again flows to the lower side of the control valve 56 through the annular chamber 84 and the holes 86. The control valve quickly seals off the lower chamber 64 and air passes between the packing 88 and the driver 46 to bring the lower chamber back to full line pressure. As the pressure in the lower chamber increases the driver piston 44 is displaced upwardly toward its inactive position, recompressing the air in the upper chamber 62 and in the accumulator 64 to the desired pressure. The initial upward movement of the piston 44 is quite rapid but is effectively slowed down as the pressure in the upper chamber increases; thus there is no shock when the piston 44 reaches the end of its return stroke. Usually the driver piston does not return to its uppermost position until the pressure in the upper chamber 62 is reduced a slight amount at which time the piston 44 will be displaced upwardly to an extent sufficient to open the pressure regulating valve 96 against the action of the spring 98 allowing further air to enter the upper chamber 62 and the accumulator 64 increasing the pressure to the desired value whereupon the piston will be moved away from the valve 96 and the valve will again close.

With the removal of the gun from the workpiece and the return of the pilot valve 106 to its lower position relative to the two diameter bore 80, the pressurized air in the signal line 30 is vented to atmosphere through the passageway 142 and a passageway 143 in the middle of the valve 106. The depressurization of the line 38 permits the piston 163 to return to its right-hand position thus causing lines and 162. again to become pressurized and line 165 to be vented to atmosphere to return the piston 161 to its right-hand position. Thereupon the lift slide 154 moves downwardly and the separating segment 158 moves to deliver the endmost nail to the raceway in alinement with the, delivery tube 28. Although the line 165, is now vented, the piston 164 of the time delay valve 164 does not return toits left-hand position until a blast of air passes through line 162 to blow the nail through the delivery tube 128 to the gun. The cycle of operation having been completed the gun is now ready to insert another nail.

When the supply line 26 is disconnected after operation of the gun 20, the air compressed within the upper chamber 62 andthe accumulator 64 cannot vent through the valve 96. It is necessary that the gun 20 not be fired except when pressed against a workpiece to bring the quill locking sleeve 130 out of locking relationship with respect to the quill 114. Therefore, the ball check 82 (Fig. is provided to prevent the control valve 56 from being actuated when the pressure in the supply line 26 is cut off. Pressure is thus held in the chamber 60 until leakage by the ball check 82 relieves it. When the line 26 is vented pressure on top of the valve 96 is relieved. The pressure in chamber 62 forces the valve 96 open allowing the piston to move upward due to thelocked-in pressure in the chamber 60 which fully opens the valve 96 and fully vents the chamber 62. Chamber 60 now slowly leaks pressure by ball check 82 until at atmospheric pressure. Thus it is always insured that the driver ends up in the inactive position when the line 26 is depressurized and the driver cannot move downward to destroy the locked quill.

It will be noted that there are only two springs in the present gun, namely, the pressure regulating valve spring 98 and the spring 140 in the nose piece 24. Furthermore, these springs in no way affect control of the actual operation of the air motor which provides the driving force for the inserting gun. The spring 98 is of course of great importance in controlling the pressure differential between the upper chamber 62 and the lower chamber 60 but does not actually control operation of the driver piston 44. This feature wherein fluid force differentials are utilized to displace the driver piston 44, the control valve 56 and the pilot valve 106 makes for a very simple and highly effective construction. It should be noted that with the above advantages in mind, it is further possible to return the driver piston 44 to its ready position without venting the upper chamber 62 to atmosphere and yet employ a single diameter driving piston. This leads to a great economy in air consumption in the operation of the present device as well as simplicity and reliability of operation. Furthermore, the provision of an accumulator surrounding the cylinder 42 of the air motor serves an added purpose in allowing extremely light weight construction since the cylinder 42 is effectively protected from damage by abuse in the normal use of this inserting gun.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

l. A fluid motor comprising a cylinder, a piston slidable therein and separating said cylinder into first and sec ond chambers on either side thereof, a single line for delivering compressed fluid to said fluid motor, means for introducing fluid under pressure from said line into said first chamber whereby a force will be exerted on said piston to displace it to an inactive position, a passageway leading from said line to said second chamber, means interposed in said passageway for admitting a limited supply of fluid under pressure to said second chamber when said piston is in the inactive position to maintain in said second chamber a pressure less than the pressure in said first chamber, and means for releasing the pressurized fluid from said first chamber to allow the fluid in said second chamber to expand and thereby drive said piston away from said inactive position and toward a force delivering position.

2. A fluid motor comprising a cylinder, a piston slidable therein and separating said cylinder into first and second chambers on either side thereof, valve means for introducing and maintaining fluid under pressure in said first chamber to maintain said piston in an inactive position, means for maintaining in said second chamber compressed fluid which is at a pressurev below the pressure in said first chamber when saidvpiston is in said inactive position, means for displacing said valve means to release the pressurized fluid from said first chamber to allow the fluid in said second chamber to expand and thereby drive said piston away from said inactive position and to a. force delivering position, and means for varying the pressure in said second chamber whereby the energy with which said piston is driven to its force deliveringposition may be controlled.

3. A fastener inserting gun comprising a cylinder, a piston slidable therein and separating said cylinder into first and second chambers on either side thereof, a driver extending from said piston and beyond said cylinder, valve means for introducing and maintaining fluid under pressure in said first chamber to maintain said piston in an inactive position, means formaintaining in said second chamber compressed fluidwhich is at a pressure below the pressure in said first chamber when said piston is in said inactive position, and means for displacing said valve means to release the pressurized fluid from said first chamber to allow the fluid in said second chamber to expand and thereby move said piston and driver away from said inactive position and to a force delivering position.

4. A fastener inserting gun comprising a cylinder, a

piston slidable therein and separating said cylinder into first and second chambers on either side thereof, an accumulator for containing compressed fluid which is in direct communication with saidsecond chamber, a driver extending from said piston and beyond said cylinder, valve means for introducing and maintaining fluid under pressure in said first chamber to maintain said piston inan inactive position, means f or maintaining in said second chamber and in said accumulator compressed fluid which is at a pressure below the pressure in said first chamber when said piston is in said inactive position, and means for displacing said valve means to release the pressurized fluid from said first chamber to allow the fluid in said second chamber and in said accumulator to expand and thereby drive said piston and driver away from said inactive position and to a force delivering position. 5. A fastener inserting gun comprising a cylinder, a piston slidable therein and separating said. cylinder into first and second chambers on either side thereof, a driver extending from saidpiston andv beyond said cylinder, at single line for delivering compressed fluid tosaid insert ing gun, means for introducing fluid under pressure from said line into said first chamber whereby a force will be exerted on said piston to displace it to an inactive position, a passageway leading from said line to said second chamber, means interposed in said passageway for adinitting a limited supply of fluid under pressure to said second chamber when said piston is in the inactive position to maintain in said second chamber a pressure less than the pressure in said first chamber, and means for releasing the pressurized fluid from said first chamber to allow the fluid in said second chamber to expand and thereby drive said piston and driver away from said inactive position and to aforce delivering position.

.6. A f astener inserting gun comprising a cylinder, a piston slidable therein and separating said cylinder into first and second chambers on either side thereof, a driver extending from said pistonv and. beyondisaid cylinder, a single line for delivering compressed fluid to said inserting gun, means for introducing fluid under pressure from said line into said first chamber whereby a force will be 'exertedon said piston to displace it to an inactive position, a passageway leading from saidline tosaid second chamber, a valve interposed in said passageway for controllingthe admission of fluid tosaid second chamber,

11 yieldable pressure means normally holding said valve closed, means responsive to movement of said piston toward said inactive position for opening said valve whereby pressurized fluid is introduced into said second chamber until the pressure in said second chamber, in combination with the yieldable pressure means, displaces said piston to a pointwhere said valve is closed thereby introducing fluid into said second chamber which is at a pressure less than the pressure in said first chamber, and means for releasing the pressurized fluid from said first chamber to allow the fluid in said second chamber to expand and thereby drive said piston and driver away from said inactive position and to a force delivering position.

7. A fastener inserting gun comprising a cylinder, a piston slidable therein and separating said cylinder into first and second chambers on either side thereof, a driver extending from said piston and beyond said cylinder, a single line for delivering compressed fluid to said inserting gun, means for introducing fluid from said line into 'said first chamber whereby a force will be exerted on said piston to displace it to an inactive position, an accumulator for containing pressurized fluid which is in direct communication with said second chamber, a passageway leading from said line to said chamber and accumulator, means interposed in said passageway for admitting a limited supply of fluid under pressure to said second chamher when said piston is in the inactive position to maintain in said second chamber a pressure less than the in said first chamber, and means for releasing the pressurized fluid from said first chamber to allow the fluid in said second chamber and in said accumulator to expand and thereby drive said piston and driver away from said inactive position and to a force delivering position. t

8. A fastener inserting gun comprising a cylinder, a piston slidable therein and separating said cylinder into first andsecond chambers on either side thereof, a driver extendingfrom said piston and beyond said cylinder, valve means for introducing and maintaining fluid under pressure in said first chamber to maintain said piston in an inactive position, an accumulator which is formed by a concentric casing surrounding said cylinder through its entire length and which is in direct communication with said second chamber, means for introducing compressed fluid into said second chamber and accumulator,

and means for releasing said valve means whereby said piston and driver are driven from said inactive position to a force delivering position by the fluid compressed in said accumulator and said second chamber.

9. A fluid motor comprising a cylinder, a piston slidable therein and separating said cylinder into first and second chambers on either side thereof, a plurality of passageways for venting said first chamber, a valve member movable in a direction axially of said cylinder for alternatively sealing off said first chamber from and exposing it to said passageways, means for introducing fluid under pressure against the face of said valve member remote from said first chamber to maintain said valve member: in sealing position, said valve member having means permitting the passage of fluid therethrough to said first chamber whereby fluid under pressure enters said first chamber to displace said piston to an inactive position, means within said second chamber for exerting at all times a force against said piston which tends to urge said piston away from said inactive position and to a force ton to be driven toward said force delivering position by the force within said second chamber.

I O A fastener inserting gun comprising a cylinder,

a piston slidable therein and separating said cylinder into first and second chambers on either side thereof, a driver extending from said piston through said first chamber and beyond said cylinder, a plurality of passageways for venting said first chamber, a valve member movable in a direction axially of said cylinder for alternatively sealing off said first chamber from and exposing it to said passageways, means for introducing fluid under pressure against the face of said valve member remote from said first chamber to maintain said valve member in its sealing position, said valve member having means permitting the passage of fluid theret'hrough to said first chamber, whereby fluid under pressure enters said first chamber to displace said piston to an inactive position, said introducing means including a pilot valve which in one position permits passage of fluid to said valve member and in a second position releases the fluid pressure acting against said valve member, means within said second chamber for exerting at all times a force against said piston which tends to urge said piston away from said inactive position and to a force delivering position, and means for moving said pilot valve to its second position whereby fluid pressure acting against said valve member is released and said member is displaced from its sealing position by the fluid pressure in said first chamber and said fluid is vented through said passageways to allow said piston to be driven toward said force delivering position by the force within said second chamber.

11. A fastener inserting gun comprising a cylinder, a piston slidable therein and separating said cylinder into first and second chambers on either side thereof, a driver extending from said piston through said first chamber and beyond said cylinder, an accuculator for containing compressed fluid which is in direct communication with said second chamber, a plurality of passageways for venting said first chamber, a valve member movable in a direction axially of said cylinder for alternatively sealing off said first chamber from and exposing it to said passageways, means for introducing fluid under pressure against the face of said valve member remote from said first chamber to maintain said valve member in its sealing position, said valve member having means permitting the passage of fluid therethrough to said first chamber Whereby fluid under pressure enters said first chamber to displace said driver piston to an inactive position, means for maintaining in said second chamber and in said accumulator compressed fluid which is at a pressure below the pressure in said first chamber when said driver piston is in its inactive position, and means for releasing the fluid pressure acting against said valve member whereby said member is displaced from its sealing position by the fluid pressure in said first chamber and said fluid is vented through said passageways to allow the fluid in said second chamber and in said accumulator to expand and thereby drive said piston and driver away from said inactive position and to a force delivering position.

12. A fastener inserting gun comprising a cylinder, a piston slidable therein and separating said cylinder into first and second chambers on either side thereof, a driver extending from said piston and beyond said cylinder, a single line for delivering compressed fluid to said inserting gun, a plurality of passageways for venting said first chamber, a valve member movable in a direction axially of said cylinder for alternatively sealing ofl. said first chamber from and exposing it to said passageways, means for introducing fluid under pressure from said line against the face of said valve member remote from said first chamber to maintain said valve member in its sealing position, said valve member having means permitting the passage of fluid therethrough to said first chamber, whereby fluid under pressure enters said first chamber to dis place said driver piston to an inactive position, a passageway leading from said line to said second chamber, means interposed in said passageway for admitting a limited supply of fluid under pressure to said second chamber when said piston is in the inactive position to maintain in said second chamber a pressure less than the pressure in said first chamber, and means for releasing the fluid pressure acting against said valve member whereby said valve member is displaced from its sealing position by the fluid pressure in said first chamber, and said fluid is vented through said passageways to allow the fluid in said second chamber to expand and thereby drive said piston and driver away from said inactive position and to a force delivering position.

13. A fastener inserting gun comprising a cylinder, a piston slidable therein and separating said cylinder into first and second chambers on either side thereof, a driver extending from said piston and beyond said cylinder, a single line for delivering compressed fluid to said inserting gun, a plurality of passageways for venting said first chamber, a valve member for sealing off said first chamber from said passageways, said valve member having means permitting the passage of fluid therethrough to said first chamber, means for introducing fluid under pressure from said line against the outer face of said valve member whereby it is maintained in its sealing position and fluid enters said first chamber to maintain said driver piston in an inactive position, a passageway leading from said line to said second chamber, means interposed in said passageway for admitting a limited supply of fluid to said second chamber whereby the pressure in said second chamber is less than the pressure in said first chamber when the piston is in said inactive position, means for releasing the fluid pressure acting against said valve member whereby said member is displaced from its sealing position by the fluid pressure in said first chamber and said fluid is vented through said passageways to allow said piston and driver to be driven to a force delivering position by the expansion of the fluid within said second chamber, and means for preventing the release of the fluid pressure acting against said valve member when the pressure in said delivery line is shut off whereby said inserting gun may be disengaged from a source of pressurized fluid with its driver piston in its inactive position.

14. A fastener inserting gun comprising a cylinder, a piston slidable therein and separating said cylinder into first and second chambers on either side thereof, a driver extending from said piston and beyond said cylinder, valve means for introducing and maintaining fluid under pressure in said first chamber to maintain said piston in an inactive position, means for maintaining in said second chamber compressed fluid which is at a pressure below the pressure in said first chamber when said driver piston is in said inactive position, means for displacing said valve means to release the pressurized fluid from said first chamber to allow the fluid in said second chamber to expand and thereby drive said piston and driver away from said inactive position and to a force delivering position, and means for varying the pressure in said second chamber whereby the energy imparted to said piston and driver may be matched to the energy necessary for driving a fastener.

15. A fastener inserting gun comprising a cylinder, a piston slidable therein and separating said cylinder into first and second chambers on either side thereof, a driver extending from said piston and beyond said cylinder, a single line for delivering compressed fluid to said inserting gun, means for introducing fluid from said line into said first chamber whereby said chamber is at line pressure and said piston is maintained in an inactive position, a passageway leading from said line to said second chamber, a valve interposed in said line for controlling the admission of fluid to said second chamber, yieldable means normally holding said valve closed, means responsive to movement of said piston for opening said valve whereby pressurized fluid is introduced into said second chamber until the pressure in said second chamber in combination with the yieldable means displaces said piston to a point where said valve is closed thereby introducing fluid into said second chamber which is. at a pressure less than the pressure in said first chamber when the driver piston is in its inactive position, means for varying the force of said yieldable means whereby the pressure of the fluid in said second chamber may be varied, and means for releasing the pressurized fluid from said first chamber to allow the fluid in said second chamber to expand and thereby drive said piston and driver away from said inactive position and to a force delivering position.

16. A fastener inserting gun comprising a cylinder, a driver piston slidable therein and separating said cylinder into first and second chambers on either side thereof, a plurality of passageways for venting said first chamber, a valve member sealing off said first chamber from said passageways, said valve member having means permitting the passage of fluid therethrough to said first chamber, means for introducing fluid under pressure against the outer face of said valve member whereby it is maintained in its sealing position and fluid enters said firstchamber to maintain the driver piston in an inactive position, said introducing means including a pilot valve which is movable between a first position in which fluid is introduced against the outer face of said valve member and a second position in'which the fluid acting against said valve member is released, a fluid conduit extending from said gun at a point adjacent said pilot valve whereby when said pilot valve is in its second position the conduit is pressurized to initiate the delivery of a fastener to the gun, means within said second chamber for exerting at all times a force against said piston which tends to urge said driver piston away from said inactive position and to a. force delivering position, and means for moving said pilot valve to its second position whereby the fluid acting against said valve member is released and said member is displaced from its sealing position by the fluid pressure in said first chamber and said fluid is vented through said passageways to allow said driver piston to be driven toward said force delivering position by the force within said second chamber.

17. A fluid motor comprising a cylinder, a piston slidable therein and separating said cylinder in-to first and second chambers on either side thereof, a plurality of passageways for venting said first chamber, a valve member for sealing off said cylinder from said passageways, said valve member having means permitting the passage of fluid therethrough to said first chamber, means for introducing fluid under pressure against the outer face of said valve member whereby it is maintained in its sealing position and fluid enters said first chamber to maintain said piston in an inactive position, means within said second chamber for exerting at all times a force against said piston which tends to urge said piston away from said inactive position and toward a force delivering position, said introducing means including a pilot valve having two spools with opposed surfaces one of which is larger in area than the other, said pilot valve being movable in a closed chamber, means for introducing fluid between said spools whereby said pilot valve is maintained in a first position in which fluid is introduced against the outer face of said valve, and means for shifting said pilot valve to a second position in which the fluid pressure acting against said valve member is released and said member is displaced from its sealing position by the fluid pressure in said first chamber and said fluid is vented through said passageways to allow said piston to be driven to its force delivering position by the force in said second chamber.

18. A fastener inserting gun comprising a cylinder, a piston slidable therein and separating said cylinder into first and second chambers on either side thereof, a driver extending from said piston and beyond said cylinder, a plurality of passageways for venting said first chamber, a valve member for sealing off said first chamber from said passageways, said valve member having means permitting the passage of fluid therethrough to said first chamber, means for introducing fluid pressure against the outer face of said valve member whereby it is maintained in its sealing position and fluid enters said first chamber to maintain said driver piston in an inactive position, said introducing means including a pilot valve which in a first postion permits passage of fluid to said valve member and in a second position releases the fluid pressure acting against said valve member, means within said second chamber for exerting at all times a force against said driver piston which tends to urge said piston away from said inactive position and toward a force delivering position, means for normally maintaining said pilot valve in its first position, and means extending from said gun which upon engagement with a workpiece will displace said pilot valve to its second position whereby fluid pressure acting against said valve member is released and said member is displaced from its sealing position by the fluid pressure in said first chamber, and said fluid is vented through said passageways to allow said piston and driver tosbe driven toward said force delivering position by the force .within said second chamber.

l9. A fastener inserting gun comprising a fluid motor having a driver piston and a driver extending therefrom, means 'for locating a fastener in alinement with said driver, said locating means being yieldably mounted at one end of saidgun, a conduit leading to said locating means through which fasteners may be delivered a control valve for actuating said motor, a pilot valve movable relative to said fluid motor which may be displaced to actuate said control valve, means connecting said locating means and said pilot valve whereby when said locating means are pressed against a workpiece relative movement takes place between said fluid motor and said pilot valve to actuate said fluid motor and thereby cause a fastener located in alinement with said driver to be driven.

20. A fastener inserting gun comprising a fluid motor having a driver piston and a driver extending therefrom, means for locating a fastener in alinement with said driver, said locating means being slidably mounted at one end of said gun, a pilot valve movable relative to said fluid motor for controlling fluid flow thereto, a conduit leading to said locating means through which fasteners may be delivered, means for retaining a fastener within said locating means, and means connecting said locating means and said pilot valve whereby when said locating means are pressed against a workpiece relative movement takes place between said fluid motor and said pilot valve to actuate said fluid motor and said locating means are also displaced with respect to said retaining means thereby permitting fasteners to be driven from said locating means by said driver.

' 21. A fastener inserting gun comprising a fluid motor having a cylinder, a driver piston and a driver extending therefrom, means for locating a fastener in alinement with said driver, a pilot valve movable relative to said fluid motor for controlling fluid flow to said motor, a conduit leading to said locating means through which fasteners may be delivered, means for retaining a fastener within said locating means comprising a sleeve surrounding said locating means yieldably mounted with respect to said fluid motor, said locating means being longitudinally movable with respect to said cylinder, and means connecting said locating means and said pilot valve whereby when said locating means are pressed against a workpiece relative movement takes place between said fluid motor and said pilot valve to actuate said fluid motor and said locating means are displaced with respect to said retaining means, and upon release from said workpiece the locating means may return to their normal position before the retaining means.

22. A fastener inserting gun comprising a cylinder, a piston slidable therein and separating said cylinder into first and second chambers on either side thereof, a driver extending from said piston and beyond said cylinder, a single line for delivering compressed fluid to said inserting gun, a plurality of passageways for venting said first chamber, a valve member for sealing off said passageways, said valve member having means permitting the passage of fluid therethrough to said first chamber, means for introducing fluid under pressure from said line against the outer face of said valve member whereby it is maintained in its sealing position and fluid enters said first chamber to maintain said driver piston in an inactive position, a passageway leading from said line to said second chamber, means interposed in said passageway for admitting a limited supply of fluid to said second chamber whereby the pressure in said second chamber is less than the pressure in said first chamber when the piston is in said inactive position, means for locating a fastener in alinement with said driver, said locating means being slidably mounted at one end of said gun, means operative in response to movement of said locating means with respect to said cylinder for releasing said fluid pressure against said valve member, and means for preventing the release of the fluid pressure acting against said valve memher when the pressure in said delivery line is shut off, whereby said inserting gun may bedisengaged from a source of pressurized fluid with the driver piston remaining in an inactive position.

References Cited in the file of this patent UNITED STATES PATENTS 1,014,639 Colwell Jan. 16, 1912 2,498,503 Papalia Feb. 21, 1950 2,625,682 Cristiano Jan. 20, 1953 2,679,826 Leavell June 1, 1954 2,707,277 Aldrich May 3, 1955