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US3229589A - Impact tool and pneumatic piston return system therefor - Google Patents

Impact tool and pneumatic piston return system therefor Download PDF

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Publication number
US3229589A
US3229589A US416287A US41628764A US3229589A US 3229589 A US3229589 A US 3229589A US 416287 A US416287 A US 416287A US 41628764 A US41628764 A US 41628764A US 3229589 A US3229589 A US 3229589A
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United States
Prior art keywords
piston
cylinder
pressure
fluid
pressure chamber
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US416287A
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English (en)
Inventor
Langas Arthur
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Signode Corp
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Signode Corp
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Publication date
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Priority to US416287A priority Critical patent/US3229589A/en
Priority to GB47??9/65D priority patent/GB1087180A/en
Priority to DE19651576158D priority patent/DE1576158B1/de
Priority to SE15343/65A priority patent/SE311873B/xx
Priority to CH1662565A priority patent/CH448754A/de
Priority to ES0320363A priority patent/ES320363A1/es
Application granted granted Critical
Publication of US3229589A publication Critical patent/US3229589A/en
Anticipated expiration legal-status Critical
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01B—MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES
    • F01B17/00—Reciprocating-piston machines or engines characterised by use of uniflow principle
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25C—HAND-HELD NAILING OR STAPLING TOOLS; MANUALLY OPERATED PORTABLE STAPLING TOOLS
    • B25C1/00—Hand-held nailing tools; Nail feeding devices
    • B25C1/04—Hand-held nailing tools; Nail feeding devices operated by fluid pressure, e.g. by air pressure
    • B25C1/041—Hand-held nailing tools; Nail feeding devices operated by fluid pressure, e.g. by air pressure with fixed main cylinder
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01B—MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES
    • F01B17/00—Reciprocating-piston machines or engines characterised by use of uniflow principle
    • F01B17/02—Engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/08—Characterised by the construction of the motor unit
    • F15B15/14—Characterised by the construction of the motor unit of the straight-cylinder type
    • F15B15/1423—Component parts; Constructional details
    • F15B15/1447—Pistons; Piston to piston rod assemblies
    • F15B15/1452—Piston sealings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/08—Characterised by the construction of the motor unit
    • F15B15/14—Characterised by the construction of the motor unit of the straight-cylinder type
    • F15B15/1423—Component parts; Constructional details
    • F15B15/1476—Special return means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/08—Characterised by the construction of the motor unit
    • F15B15/14—Characterised by the construction of the motor unit of the straight-cylinder type
    • F15B15/149—Fluid interconnections, e.g. fluid connectors, passages
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/20—Other details, e.g. assembly with regulating devices
    • F15B15/22—Other details, e.g. assembly with regulating devices for accelerating or decelerating the stroke
    • F15B15/226—Other details, e.g. assembly with regulating devices for accelerating or decelerating the stroke having elastic elements, e.g. springs, rubber pads

Definitions

  • the present invention relates to impact tools of the type employing a pneumatically operable piston and cylinder assembly for powering the driver ordinarily associated with such tools.
  • the invention has particular reference to a novel means for returning the piston of such an assembly to its retracted position after the piston has delivered its power stroke.
  • pneumatically operable piston and cylinder assemblies may, broadly, be divided into two groups. In one group the piston is returned by spring pressure and in the other group the piston is returned by air pressure. It is to this latter class of piston and cylinder assemblies that the present invention pertains.
  • Piston and cylinder assemblies which rely solely upon spring pressure for return of the piston to its retracted position are possessed of numerous limitations that render the same unsuitable for use where an extremely fast power stroke, terminating in maximum power delivery at the time of impact, is desired. Principal among these is the inability of the spring to uniformly absorb the compression exerted upon it by the fast moving piston during the power stroke. Due to the inertia of the spring, particularly if it is comprised of a large number of convolutions, the quick movement of the piston will not displace the entire length of the spring, only the first few spring convolutions in the vicinity of the piston becoming compressed and the remainder thereof remaining static.
  • the piston initially delivers an impact to the adjacent end of the spring which creates a shock wave that does not have time to traverse the entire length of the spring before the piston is at the end of its power stroke.
  • This causes the first several convolutions of the spring to go solid while the remainder of the spring is not compressed.
  • the spring is not immediately effective to return the piston inasmuch as the compressed convoluti-ons of the spring cannot find reaction support and must distribute their potential expansive force to the uncompressed portions of the spring before the entire spring can become effective to return the piston.
  • Such a spring action not only delays the piston return, but it also damages the spring due to repeated impact between adjacent spring convolutions which go solid during each power stroke of the piston.
  • a further limitation in connection with the use of a spring for returning the piston resides in the relatively great counter-thrust which is offered to the piston by the spring during its power stroke, this counter-thrust increasing progressively and being at its maximum at the time of impact by the driver, thus detracting from the total power delivered.
  • Placement of the pressure chamber at the end of the cylinder on the driver side of the piston requires a cylinder of undue length, While placement of the pressure chamber at one side of or concentric with the cylinder involves the use of complicated and unreliable valve porting and valve arrangements, as well as increasing the overall bulk of the system. Regardless of the position of the fixed pressure chamber, the total volume of air collected in the chamber during the power stroke of the piston must be sufiicient in mass to effectively fill the cylinder when the piston is completely returned and maintain an appreciable degree of return pressure upon the piston to hold it in its retracted position until the next succeeding power stroke thereof.
  • the present invention is designed to overcome the above-noted limitations that are attendant upon the construction and operation of conventional piston return systems, whether the same be of the spring return or the air return type. Accordingly the invention contemplates the provision of a novel air return system wherein the piston, after it has completed its effective power stroke and delivered its impact, is returned to its retracted position gradually and uniformly with sufiicient rapidity to satisfy the requirements of the particular tool involved or service required, yet at a rate which is not excessive.
  • the cylinder wall be of tapering design, the wall tapering in the direction of movement of the piston during its power stroke and on a small slant angle.
  • the piston which is reciprocable axially within the cylinder, is provided with an outwardly facing continuous annular recess therein which opposes the tapered wall of the cylinder and, in combination therewith, defines a variable volume annular pressure chamber or air reservoir which surrounds the piston and the capacity of which decreases during the power stroke of the piston and increases during the return stroke thereof.
  • the pressure chamber is sealed from both the large and the small ends of the cylinder.
  • the pressure chamber communicates through an air passage in the body of the piston with the large end of the cylinder and a check valve disposed in the passage is effective to admit air to the pressure chamber when air pressure in the large end of the cylinder exceeds the air pressure in the chamber and to prevent air from escaping from the chamber when the reverse is true.
  • the small end of the cylinder is bled to the atmosphere and at no time has communication with the pressure chamber.
  • Means are provided for selectively admitting air under working pressure to the large end of the cylinder to drive the piston during its power stroke and for bleeding the large end of the cylinder to the atmosphere during the return stroke of the piston.
  • air thus enters the large end of the cylinder it is admitted to the pressure chamber by the check valve and places the chamber under full working air pressure.
  • the piston is driven forwardly to commence the power stroke thereof.
  • the volume of air in the pressure chamber progressively decreases, as heretofore set forth, due to the tapered Wall of the cylinder.
  • the inward taper of the cylinder wall below the piston opposes any tendency for downward movement of the piston but the outward taper of thecylinder wall above the piston offers no such opposition to upward movement of the piston and the latter is constrained to move uniformly and gradually upwardly within the cylinder.
  • the expansive pressure of air within the pressure chamber constitutes the sole motivating means for moving the piston upwardly within the cylinder, air pressure on opposite ends of the piston being equalized since both ends of the cylinder are in communication with the atmosphere.
  • the specific slant angle of the frusto-conical wall of the cylinder, the slant height thereof, the capacity of the pressure chamber and the anti-friction characteristics of the sealing means whereby the pressure chamber is sealed to the tapered wall of the cylinder are selected according to engineering expediencies so that when the piston is in its fully advanced position at the end of its power stroke and is dis-posed at the small end of the cylinder, the pressure of air within the pressure chamber will be sufficiently great as to exert an expansive action on the cylinder wall throughout the entire return stroke of the piston with sufiicient residual air pressure remaining within the pressure chamber. .to .retairrthe ,pistonin itsv retracted or nor.-
  • the improved piston return system of the present invention as briefly outlined above has been designed for use primarily in connection with portable impact tools such as magazine fed stapling and nailing machines, and other devices which rely for their action uponthe pressure stroke of a driver. It is to be distinctly understood however that the invention is not necessarily limited to such use and piston and cylinder assemblies constructed in accordance with the principles of the invention may, with or without suitable modification, as required, be employed for other purposes too numerous to mention. Irrespective however of the particular use to which the invention may be put, the essential features thereof are at all times preserved.
  • the piston return system of the present invention has been illustrated herein for exemplary purposes as being operatively embodied in a portable impact tool in the form of a nailing machine which, in itself, is possessed of certain novel features relating principally to a pneumatic control whereby working air pressure may selec tively be applied to and exhausted from the large end of the tapered cylinder associated with the piston return system.
  • a novel piston return system such as has briefiy been outlined above constitutes the principal object of the invention but other objects relating to the construction and operation of the impact tool also are present.
  • an impact tool which is extremely simple in its construction and which therefore may be manufactured at a low cost; one which is comprised of a minimum number of parts, especially moving parts, and which therefore is unlikely to get out of order; one which is rugged and durable and which therefore will withstand rough usage; one which is capable of ease of assembly and disassembly for purposes of inspection of parts, replacement or repair thereof; and one which, otherwise, is well adapted to perform the services required of it, are further desirable features which have been borne in mind in the production and development of the present invention.
  • FIG. 1 is a sectional view, somewhat schematic in its representation, taken substantially centrally and vertically through a piston and cylinder assembly embodying the novel pistonv return system of the ,present invention, the.
  • FIG. 2 is a sectional view similar to FIG. 1, showing the piston during its power stroke and at approximately 5 in the machine cycle;
  • FIG. 3 is a sectional view similar to FIG. 1, showing the piston during its power stroke and at approximately in the machine cycle;
  • FIG. 4 is a sectional view similar to FIG. 1, showing the piston during its power stroke and at approximately 30 in the machine cycle;
  • FIG. 5 is a sectional View similar to FIG. 1, showing the piston at the completion of its power stroke and at 180 in the machine cycle;
  • FIG. 6 is a sectional view similar to FIG. 1, showing the piston during its return stroke and at approximately 270 in the machine cycle;
  • FIG. 7 is a sectional view taken substantially centrally and longitudinally through a portable nailing machine constructed according to the present invention and embodying the novel piston return system thereof;
  • FIG. 8 is a sectional view taken substantially along the line 88 of FIG. 7;
  • FIG. 9 is a sectional view taken substantially along the line 9-9 of FIG. 7;
  • FIG. 10 is an enlarged fragmentary detail sectional view of a portion of the structure shown in FIG. 1 and in the vicinity of a check valve controlled air passage employed in connection with the air return system of the present in vention;
  • FIG. 11 is a fragmentary sectional view taken substantially along the line 1111 of FIG. 8 but showing a slightly modified form of piston operatively installed within the cylinder.
  • a pneumatic piston and cylinder assembly has been designated in its entirety at 10 and includes a cylinder 12 within which a piston is axially reciprocable.
  • the cylinder 12 is of open-ended tubular construction and the opposite ends thereof are closed by upper and lower circular heads or end walls 16 and 18 respectively.
  • the lower end wall is provided with a bleeder passage 19 therein.
  • the inner working surface or wall 29 of the cylinder 12 is of tapered or frusto-conical configuration, the cone having a small slant angle and a slant height commensurate with the desired stroke of the piston 14.
  • the specific slant angle of the frusto-conical cylinder wall 20 is not critical, the particular angle selected for illustration herein being on the order of 4. However, greater or lesser slant angles are contemplated.
  • the piston 14 is generally of cylindrical design and it is provided with a shallow annular recess 22 in the otherwise cylindrical side surface thereof.
  • an expansible and contractible sealing element preferably, but not necessarily, in the form of an elastomeric or other resilient O-ring 24, axially and floatingly confined within an annular groove 26, makes sliding sealing contect with the tapered wall 20 of the cylinder 12.
  • a similar sealing element 28 confined within an annular groove 30, likewise makes sliding sealing contact with the wall 29.
  • the bottom or inner wall of the annular recess 22 is spaced from the tapered wall 29 of the cylinder and thus the recess, in combination with a limited vertical span of the cylinder wall, establishes a closed normally hermetically sealed pressure chamber 32 which travels or shifts bodily with the piston during the reciprocating movements of the latter.
  • the 0- rings 24 and 28 are disposed outwardly in the grooves 26 and 32 respectively and make sealing contact with the wall 29.
  • these two O-rings are compressed deep within their respective grooves.
  • the two ()-rings assume corresponding intermediate positions Within their respective grooves.
  • the annular pressure chamber 32 remains sealed by the O-rings from the opposite ends of the cylinder.
  • the piston 14 is guided in its movements by means of a plunger 34, the upper end of which is fixedly secured to the piston and which projects outwardly of the cylinder 14 through a guide bushing or sleeve 36 suitably secured in the lower end wall 18.
  • the plunger 34 thus serves to center the piston within the cylinder and prevent angular misalignment of the piston and cylinder, or lateral shifting of the piston within the cylinder. Stated otherwise, the plunger serves to maintain the piston 14 and cylinder 12 in coaxial relationship at all times.
  • Means are provided for selectively admitting air under pressure to the upper end of the cylinder 12 and bleeding air from the upper end thereof to the atmosphere, such means in the schematic illustration of FIGS. 1 to 6 inclusive assuming the form of a three-way valve V having one leg 49 thereof in communication with the upper end of the cylinder 12 through the end wall 16.
  • a sec ond leg 42 of the valve V is adapted to be connected to a source of air under pressure (not shown), while a third leg 44 communicates with the atmosphere.
  • the valve V is further provided with a rotatable valve body or core 46 which is manually operable under the control of a handle 48 either to establish communication between the two legs 46 and 44 when the handle is in the right hand full line position in which it is shown in FIG.
  • the piston 14 is formed with an air passage 50 therein, the passage establishing communication between the upper end of the cylinder 12 and the annular pressure chamber 32.
  • the passage 50 is shown as being generally of L-shape configuration, this passage may be linearly straight or of other configuration.
  • a check valve in the form of a spring-pressed ball 52, having a spring 53 associated therewith is disposed within the passage 50 and is normally maintained in sealing relation with a downwardly facing valve seat 54, the arrangement being such that when the pressure of air in the upper end of the cylinder exceeds the pressure in the pressure chamber 32, air will be conducted through the passage 50 from the upper end of the cylinder to the pressure chamber.
  • FIGS. 1 to 6 inclusive The operation of the above-described piston and cylinder assembly has been progressively and schematically illustrated in FIGS. 1 to 6 inclusive wherein one full pressure stroke of the piston 12 and one full return stroke thereof have been portrayed and regarded as constituting one full machine cycle of 360 duration.
  • the piston 12 is shown as being in its fully retracted posi- 7 tion at in the cycle.
  • the valve body 46 of the valve V is shown as assuming a position wherein the upper end of the cylinder 12 is bled to the atmosphere through the legs 40 and 44, the handle 48 being in its full line position. Upon movement of the handle 48 to the dotted line position of FIG.
  • the initial inrush of air into the upper end of the cylinder 12 will serve to unseat the ball 52 from the valve seat 54 and cause air to enter the pressure chamber 32 through the air passage 50 as shown in FIG. 2.
  • the inertia of the piston 14 and its attached plunger 34 will allow suflicient air pressure to build up within the upper end of the cylinder and the pressure chamber 32 that substantially full working pressure of air within these spaces will obtain before any appreciable downward displacement of the piston will take place.
  • the piston is shown inthe position which it assumes at 5 in the cycle and, in this position, the ball 52 remains unseated, thus indicating that air still is entering the pressure chamber 32 and pressure is building up therein.
  • the ball 52 remains unseated but at such point in the cycle it may be assumed that the pressure of air within the pressure chamber 32 now approaches closely working pressure.
  • the return or upward stroke of the piston 14 is initiated by moving the handle of the valve V from the full line position thereof shown in FIG. 5 to the dotted line position thereof, whereupon communication will be established between the legs 40 and 44 of the valve V and pressure will be relieved in the upper end of the cylinder 12. Pressure of air within the pressure chamber 32 at this time will be at a maximum since the piston 14 is at the bottom of its stroke and consequently occupies a position wherein the volume of entrapped air within the pressure chamber is at a minimum.
  • the volume of the pressure chamber 32 will increase and thus, according to Boyles law of thermodynamics, the pressure of the entrapped air within the pressure chamber will gradually decrease. Such progressive decrease in pressure as the piston 14 rises within the cylinder 12 will offset or counteract any tendency for the piston to accelerate during its return stroke.
  • the piston 14 may be caused to perform its return stroke with substantially con stant linear velocity.
  • FIGS. 7 to 10 inclusive the above-described system of piston return has been shown as being operatively embodied in a portable gun-type percussion or impact tool in the form of an air operated, magazine fed,-nailing machine which has been designated in its entirety at 100.
  • the impact tool involves in its general organization a composite tool casing 191 including a generally tubular body portion 102 having inturned upper and lower retaining flanges 104 and 105 withinlwhich there is press.
  • piston and cylinder assembly 110 constructed according to the principles set forth in connection with the previously described piston and cylinder assembly 10 and having the novel piston return system of the present invention embodied therein.
  • the piston and cylinder assembly 110 is identical with the piston and cylinder assembly 10 and therefore, in order to avoid needless repetition of description, similar characters of reference but of a higher order have been applied to the corresponding parts as between the disclosures of FIGS. 7 to 10 inclusive, and FIGS. 1 to 6 inclusive respectively.
  • the upper end of the plunger 134 is threadedly received as at 1611 in the piston 114 and is secured in posi tion therein by a nut and washer assembly 152 disposed within the shallow recess 149.
  • the plunger 134 constitutes the driver or hammer of the tool 100 and its lower end is guided in an upstanding boss 164 formed on the lower end wall 118.
  • This end wall 118 is established by the provision of a nose piece 166 suitably secured to the lower open end of the tubular casing 102 and having a magazine assembly 168 operatively secured in position thereon for feeding a series of nails 170, one at a time, into operative position beneath the driver or hammer 134 for ejection from the magazine through a driver slot 171 in the usual manner of operation of conventional nailing machines of the type under consideration.
  • a tubular elastorneric bumper 172 fits within a recess 174 formed on the underneath side of the piston 114, surrounds the driver 134 and is designed for engagement with the lower end wall 118 at the end of the power stroke of the piston 114.
  • the upper end wall 116 of the tapered cylinder 112 is established by reason of the provision of an upper closure member or cap 176 of hollow construction and which is suitably secured to the upper open end of the tubular body portion 182 of the composite casing.
  • a gasket 178 is interposed between the closure member 176 and the upper rim of the body portion 192 in sealing relationship.
  • the casing is further provided with a lateral extension or handle portion 180, the outer end of which is adapted to be connected by a suitable nipple fitting 132 to a flexible conduit 184 leading to a source of air under pressure (not shown).
  • the end wall 116 overhangs the upper rim of the cylinder wall 121 as at 186 and this overhanging portion divides the interior of the easing into an upper chamber 138 and a lower chamber 191
  • the upper chamber 188 communicates with the upper end of the cylinder 112 through a port 192.
  • the two chambers 183 and 1% communicate with each other through a port 194.
  • An elongated valve spool 196 projects through the port 194 and has an enlarged lower end 193 guided in a socket 2199 provided internally in the handle portion 18%) and sealed to the wall of the socket by an O-ring 264.
  • the upper end of the valve spool 126 is provided with an enlargement 296 which is guided in a socket 2118 provided internally in the closure member 176.
  • the medial region of the valve spool 196 is formed with a third enlargement 210 which constitutes a closure valve for the port 194.
  • the socket 200 normally communicates through an air passage 212 with the chamber 190 and a ball check valve assembly 214 is adapted upon actuation of a pivoted trigger element 216 to become closed and prevent such communication between the socket 290 and chamber 191').
  • the socket 293 communicates through a passage 218 with the atmosphere and through a port 229 with the chamber 188.
  • An O-ring 222 encompasses the port 220 and is designed for sealing engagement with the enlargement 286 when the valve spool 196 is in its lowermost position. When the valve spool is in its uppermost position, the chamber 188 is bled through the port 221 and passage 218 to the atmosphere.
  • the check valve assembly 214 includes a ball valve element 224 which normally rests upon a valve seat 226 associated with a passage 228 in communication with the atmosphere.
  • the ball valve element 224 opposes a second downwardly facing valve seat 230 associated with the passage 212.
  • a thrust pin 232 is slidably disposed within the passage 228 and operates to displace the valve element 224 when the trigger element .216 is depressed.
  • the spool valve 196 will normally be maintained in its uppermost position since air pressure within the chamber 1% will be effective through the passage 212 to maintain full working pressure upon the underneath side of the enlargement 193, as well as to maintain pressure upon the closure valve 214).
  • the enlargement or closure valve 210 will therefore close the port 194 and pressure within the upper end of the cylinder 112 will be bled to the atmosphere through the port 211) and passage 218.
  • the pressure of residual air within the pressure chamber 132 will thus maintain the piston 114 in its fully retracted position due to considerations which have previously been set forth in detail in connection with the piston and cylinder assembly 10.
  • the ball valve element 214 Upon depression of the trigger element 216, the ball valve element 214 will become dislodged from the valve seat 226, thus bleeding the socket 2191] to the atmosphere through the passage 228. The ball valve element 214 will engage the valve seat 2341 and close the passage 212 so that air at working pressure within the chamber 191) will act upon the enlargement 2M and cause the spool valve 194 to move downwardly, thus opening the port 194 and at the same time causing the enlargement 296 to make sealing engagement with the O-ring 222, thus closing the port 220.
  • the ball valve element 21 Upon release of the trigger element 216, the ball valve element 21 will be returned to the seat 226, thus returning the spool valve 196 to its uppermost position and bleeding the upper end of the cylinder 112 to the atmosphere through the port 220 and passage 218, whereupon the piston 112 will perform its return stroke under the influence of expansion of air within the pressure chamher 132 in the manner previously described in connection with the piston and cylinder assembly 11 It has previously been pointed out that during the return stroke of the piston 114 the upward thrust exerted thereon by the expansive action of air within the pressure chamber 132 is maintained throughout the entire return stroke of the piston so that the expansive force of air within the pressure chamber will at no time be completely dissipated.
  • the piston 314 remains substantially the same as the piston 114, the only difference being in a slightly different shape characteristic.
  • the piston 114 is generally of cylindrical design
  • the piston 314 is generally of 'frusto-conical design and has a slant angle commensurate with the slant angle of the tapering cylinder wall 320. This results in a more equal displacement of the two annular grooves 326 and 328 from the tapered wall 320 so that when the piston is in its fully advanced position and is disposed near the small and of the tapered wall 320, both grooves are in close proximity to the wall.
  • the pressure chamber need not necessarily directly oppose and be adjacent to the tapered cylinder wall. If desired, the pressure chamber may be formed deep in the body of the piston and the entrapped air therein may be caused to exert its expansive influence on the tapered wall of the cylinder by the interpositioning of mechanical thrust means which cooperates with .the cylinder wall by a sliding action. Therefore, only insofar as the invention has particularly been pointed out in the accompanying claims is the same to be limited.
  • a cylinder having a tapered frusto-conical internal working surface of small slant angle, an axial-1y reciproca'ble piston in said cylinder and movable between a retracted position wherein it is disposed adjacent the large end of the cylinder and an advanced position wherein it is disposed adjacent the small end of the cylinder, an end wall closing the large end of the cylinder, means for selectively admitting a fluid under pressure to the large end of the cylinder to drive the piston forwardly from its retracted position to its advanced position and for relieving such fluid pressure to allow the piston to return to its retracted position, a pair of axially spaced expansible and contractible sealing rings carried by the piston and in sliding engagement with said frusto-conical working surface, the outer side surface of the piston between said sealing rings opposing said frustoconical working surface and, in combination therewith and with said sealing rings, establishing a variable-volume fluid pressure chamber which travels with the piston and the volume of which consequently is
  • a pneumatically actuated device in combination, a cylinder having a tapered frusto-conical internal working surface of small slant angle, an axially reciprocable piston in said cylinder and movable between a retracted position wherein it is disposed adjacent the large end of the cylinder and an advanced position wherein it is disposed adjacent the small end of the cylinder, an end wall closing the large end of the cylinder, valve means selectively operable to admit air at a predetermined working pressure to the large end of the cylinder to drive the piston forwardly from its retracted position to its advanced position and to relieve such working pressure to allow the piston to return to its retracted position, a pair of axially spaced expansible and contractible sea-ling rings carried by the piston and in sliding engagement with said frusto-conical working surface and, in combination therewith and with said seal-ing rings, establishing a variablevolume pressure chamber which travels with the piston and the volume of which consequently is a function of the axial displacement of the piston within the cylinder
  • a cylinder having a tapered frusto-conicai internal working surface of small slant angle, an axially reciprocable piston in said cylinder and movable between a retracted position wherein it is disposed adjacent the large end of the cylinder and an advanced position wherein it is disposed adjacent the small end of the cylinder, an end wall closing the large end of the cylinder, means for selectively admitting a fluid under pressure to the large end of the cylinder to drive the piston forwardly from its retracted position to its advanced position and for relieving such fluid pressure to allow the piston to return to its retracted position, a pair of axially spaced expansible and contractible sealing rings carried by the piston and in sliding engagement with said frustoconical working surface, the outer side surface of said piston between said sealing rings being formed with a continuous annular recess therearound, opposing said frusto-conical Working surface, said annular recess, in combination with said frusto-conical working surface and said sealing
  • a cylinder having a tapered frusto-conical internal working surface of small slant angle an axially reciprocable piston is said cylinder and movable betwen a retracted position wherein it is disposed adjacent the large end of the cylinder and an advanced position wherein it is disposed adjacent the small end of the cylinder, the end region of the piston which opposes the large end of said working surface being of greater diameter than the end region of the piston which opposes the small end of the working surface whereby the piston is generally of tapered design and on a slant angle commensurate with the slant angle of said working surface, an end wall closing the large end of the cylinder, means for selectively admitting air at a predetermined working pressure to the large end of the cylinder to drive the piston forwardly from its retracted position to its advanced position and for relieving such working pressure to allow the piston to return to its retracted position, there being a continuous annular groove formed in each end region of the piston, an axially reciprocable piston is said cylinder and
  • a pneumatic impact tool of the character described in combination a cylinder having a frusto-conical wall of small slant angle, an axially reciprocable piston in said cylinder and movable between a retracted position wherein it is disposed adjacent the large end of the cylinder and an advanced position wherein it is disposed adjacent the small end of the cylinder, an end wall at each end of the cylinder, valve means for selectively admitting air at a predetermined working pressure to the large end of the cylinder to drive the piston forwardly from its retracted position to its advanced position and for bleeding said large end of the piston to the atmosphere to relieve such working pressure therein and permit return of the piston, a driver fixedly secured to the piston and projecting through the end wall at the small end of the cylinder in guided relationship, a pair of axially spaced radially expansible and contractible sealing rings carried by the piston and in sliding engagement with said frusto-conical wall, the outer side surface of the piston between said sealing rings opposing said frusto-conical
  • a cylinder having a tapered frusto-conical internal working surface of small slan tangle, an axially reciprocable piston in said cylinder and movable between a retracted position wherein it is disposed adjacent the large end of the cylinder and an advanced position wherein it is disposed adjacent the small end of the cylinder, means for selectively admitting a fluid under pressure to the large end of the cylinder to drive the piston forwardly from its retracted position to its advanced position and for relieving such fluid pressure to allow the piston to return .to its retracted position, means in the vicinity of said piston and movable bodily with the piston establishing a fluid pressure chamber, there being a fluid passage-in said piston establishing communication between the large end of the cylinder and said pressure chamber, a check valve disposed in said passage and effective to admit fluid to the pressure chamber when the pressure therein falls below the pressure of fluid in said large end of the cylinder, the expansive force of fluid in said pressure chamber being effective in a generally
  • a cylinder having a tapered working surface of small slant angle, a piston reciprocable in said cylinder and movable between a retracted position wherein it is disposed adjacent the large end of the cylinder and an advanced position wherein it is disposed adjacent the small end of the cylinder, means for admitting air to the large end of the cylinder to drive the piston toward its advanced position, and air pressure gmeans interposed between an area of the piston and said tapered working surface and effective in any position of piston displacement to yieldingly urge the piston toward its retracted position.
  • a cylinder having a downwardly and inwardly tapered substantially frusto-conical working surface of small slant angle, a piston axially reciprocable in said cylinder and movable between a retracted position adjacent the large upper end of the cylinder and an advanced position adjacent the small lower end thereof, means for admitting fluid under pressure to the large end of the cylinder to drive the piston downwardly toward its advanced position, said piston and tapered working surface defining therebetween a pressure chamber, means for admitting fluid under pressure to said pressure chamber for entrapment therein, said piston being subject to the force exerted thereon by entrapped fluid within said pressure chamber for return of the piston to its retracted position when fluid pressure in the large end of the cylinder is relieved.
  • a cylinder having a downwardly and inwardly tapered substantially frusto-conical internal working surface of small slant angle, a piston axially reciprocable in said cylinder and movable between a retracted position adjacent the large upper end of the cylinder and an advanced position adjacent the small lower end of the cylinder, means for admitting air to the large end of the cylinder to drive the piston downwardly to its advanced position, said piston and tapered working surface defining therebetween a constant height, variable volume, pressure chamber the volume of which is a function of the axial displacement of the piston within the cylinder, and means for admitting air under pressure to said pressure chamber for entrapment therein, said piston, in all positions thereof, being subject to the force exerted upon the piston by entrapped air within said pressure chamber for return thereof to its retracted position when air pressure in the large end of the cylinder is relieved.
  • a cylinder having a downwardly and inwardly tapered substantially frusto-conical internal working surface of small slant angle, a piston axially reciprocable in said cylinder and movable between a retracted position adjacent the large upper end of the cylinder and an advanced position adjaoent the small lower end of the cylinder, means for admitting air to the large end of the cylinder to drive the piston downwardly to its advanced position, sealing means effective between each end of the piston and the tapered working surface, said sealing means, in combination with an area of the piston and an opposed area of the Working surface, establishing a pressure chamber which moves bodily with the piston, means for admitting air under pressure to said pressure chamber for entrapment therein, said piston, in all positions thereof, being subject to the force acting upon the sealing means by entrapped air within the pressure chamber for returning the piston to its retracted position when air pressure in the large end of the cylinder is relieved.
  • a fastener-applying implement a cylinder having a tapered internal working surface, a piston axially reciprocable in said cylinder and movable between a retracted position wherein it is disposed adjacent the large end of the cylinder and an advanced position wherein it is disposed adjacent the small end of the cylinder, valve means for selectively admitting air at a predetermined working pressure to the large end of the cylinder to drive the piston from its retracted position to its advanced position and for discharging air from said large end of the cylinder to permit return of the piston to its retracted position, air pressure means interposed between an area of the piston and said tapered working surface and eifective in any position of piston displacement to yieldingly urge the piston toward its retracted position, a fastener magazine connected to the cylinder and extending radially therefrom, a throat at the end of the magazine for receiving fasteners therefrom, and a driver connected to the piston for driving fasteners through said throat to apply them to the work.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Portable Nailing Machines And Staplers (AREA)
  • Treatment Of Fiber Materials (AREA)
  • Basic Packing Technique (AREA)
US416287A 1964-12-07 1964-12-07 Impact tool and pneumatic piston return system therefor Expired - Lifetime US3229589A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
US416287A US3229589A (en) 1964-12-07 1964-12-07 Impact tool and pneumatic piston return system therefor
GB47??9/65D GB1087180A (en) 1964-12-07 1965-11-11 Fluid pressure actuated device
DE19651576158D DE1576158B1 (de) 1964-12-07 1965-11-22 Einfachwirkender Druckluftzylinder mit selbsttaetiger,durch das zugefuehrte Druckmittel bewirkter Rueckbewegung
SE15343/65A SE311873B (de) 1964-12-07 1965-11-26
CH1662565A CH448754A (de) 1964-12-07 1965-12-02 Fluidumdruckbetätigte Vorrichtung
ES0320363A ES320363A1 (es) 1964-12-07 1965-12-04 Un dispositivo accionado por presion de fluido.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US416287A US3229589A (en) 1964-12-07 1964-12-07 Impact tool and pneumatic piston return system therefor

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US3229589A true US3229589A (en) 1966-01-18

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US416287A Expired - Lifetime US3229589A (en) 1964-12-07 1964-12-07 Impact tool and pneumatic piston return system therefor

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US (1) US3229589A (de)
CH (1) CH448754A (de)
DE (1) DE1576158B1 (de)
ES (1) ES320363A1 (de)
GB (1) GB1087180A (de)
SE (1) SE311873B (de)

Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3405602A (en) * 1965-12-17 1968-10-15 Fastener Corp Fluid motor having a supply-and-exhaust valve carried by the piston
US3552274A (en) * 1968-05-27 1971-01-05 Signode Corp Pneumatic piston return system for impact tools
US3638534A (en) * 1969-08-18 1972-02-01 Fastener Corp Fastener driving tool with improved pneumatic piston retaining means
US3712181A (en) * 1968-12-09 1973-01-23 Certain Teed Prod Corp Internal air assisted brake actuator
US3871604A (en) * 1972-11-02 1975-03-18 Pierre Fernand Coutin Retractable jettisoning ejector for aircrafts
US3972557A (en) * 1973-10-31 1976-08-03 Clayton Dewandre Company Limited Hydraulic cab-tilting systems
US4048905A (en) * 1976-03-29 1977-09-20 The Boeing Company Variable orifice hydraulic snubber
US4281588A (en) * 1979-06-18 1981-08-04 Sprague Devices, Inc. Reciprocating piston fluid powered motor
US4901828A (en) * 1988-03-21 1990-02-20 Monroe Auto Equipment Company Method and apparatus for controlling displacement of a piston in a shock absorber
US6186043B1 (en) * 1999-04-05 2001-02-13 Deere & Company Cushion hydraulic cylinder
US20030053846A1 (en) * 2001-09-14 2003-03-20 Kopanic Robert J. Apparatus for spraying a remote target or area
US20040020965A1 (en) * 2002-04-05 2004-02-05 Stanley Fastening Systems, L.P. Pneumatic tool with as-cast air signal passage
US6978711B1 (en) * 1999-04-22 2005-12-27 Van Der Blom Nicolaas Combination of a chamber and a piston, a pump, a motor, a shock absorber and a transducer incorporating the combination
US20070175942A1 (en) * 2003-04-04 2007-08-02 Stanley Fastening Systems, L.P. Pneumatic tool with as-cast air signal passage
US20100263975A1 (en) * 2007-10-19 2010-10-21 William Ernest Taylor Vallance Improvements in Movement Controls
US20110073631A1 (en) * 2007-06-13 2011-03-31 Tippmann Industrial Products, Inc. Combustion powered driver
US20110083865A1 (en) * 2009-10-14 2011-04-14 Sedmak Daniel D Power-Assisted Garden Tools
EP2359013A1 (de) * 2008-12-19 2011-08-24 Väderstad-Verken Aktiebolag Vorrichtung an einem hydraulischen zylinder
US20110226836A1 (en) * 2008-12-24 2011-09-22 Hamish William Hamilton Adjustable dose chamber
CN105179019A (zh) * 2015-08-07 2015-12-23 鞍钢建设集团有限公司 一种用于水下自启的气压动力装置及自启方法
WO2018070881A1 (en) * 2016-10-11 2018-04-19 S-Gun Limited A pneumatic or hydraulic mechanism
US11818973B1 (en) 2020-05-12 2023-11-21 Daniel D. Sedmak Garden tiller utilizing an impact motor

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3151658A1 (de) * 1981-12-28 1983-07-07 Hilti AG, 9494 Schaan "setzgeraet mit von hochgespannten gasen verschieblichem treibkolben"

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Publication number Priority date Publication date Assignee Title
US2710077A (en) * 1952-01-16 1955-06-07 Vibratrol Inc Hydraulic shock absorber
US2959155A (en) * 1958-02-10 1960-11-08 Powers Wire Products Company I Drive piston for a fluid operated motor

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1058847B (de) * 1957-04-10 1959-06-04 Renault Mit Differentialdruck arbeitender Druckluftzylinder

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2710077A (en) * 1952-01-16 1955-06-07 Vibratrol Inc Hydraulic shock absorber
US2959155A (en) * 1958-02-10 1960-11-08 Powers Wire Products Company I Drive piston for a fluid operated motor

Cited By (34)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3405602A (en) * 1965-12-17 1968-10-15 Fastener Corp Fluid motor having a supply-and-exhaust valve carried by the piston
US3552274A (en) * 1968-05-27 1971-01-05 Signode Corp Pneumatic piston return system for impact tools
US3712181A (en) * 1968-12-09 1973-01-23 Certain Teed Prod Corp Internal air assisted brake actuator
US3638534A (en) * 1969-08-18 1972-02-01 Fastener Corp Fastener driving tool with improved pneumatic piston retaining means
US3871604A (en) * 1972-11-02 1975-03-18 Pierre Fernand Coutin Retractable jettisoning ejector for aircrafts
US3972557A (en) * 1973-10-31 1976-08-03 Clayton Dewandre Company Limited Hydraulic cab-tilting systems
US4048905A (en) * 1976-03-29 1977-09-20 The Boeing Company Variable orifice hydraulic snubber
US4281588A (en) * 1979-06-18 1981-08-04 Sprague Devices, Inc. Reciprocating piston fluid powered motor
US4901828A (en) * 1988-03-21 1990-02-20 Monroe Auto Equipment Company Method and apparatus for controlling displacement of a piston in a shock absorber
US6186043B1 (en) * 1999-04-05 2001-02-13 Deere & Company Cushion hydraulic cylinder
US8127660B2 (en) * 1999-04-22 2012-03-06 Nicolaas Van Der Blom Combination of a chamber and a piston, a pump, a motor, a shock absorber and transducer incorporating the combination
US6978711B1 (en) * 1999-04-22 2005-12-27 Van Der Blom Nicolaas Combination of a chamber and a piston, a pump, a motor, a shock absorber and a transducer incorporating the combination
US20060032370A1 (en) * 1999-04-22 2006-02-16 Nvb Composites International A/S Combination of a chamber and a piston, a pump, a motor, a shock absorber and a transducer incorporating the combination
US20100170391A1 (en) * 1999-04-22 2010-07-08 Nvb Composites International A/S Combination of a chamber and a piston, a pump, a motor, a shock absorber and transducer incorporating the combination
US6663307B2 (en) * 2001-09-14 2003-12-16 S. C. Johnson & Son, Inc. Apparatus for spraying a remote target or area
US20030053846A1 (en) * 2001-09-14 2003-03-20 Kopanic Robert J. Apparatus for spraying a remote target or area
US20040020965A1 (en) * 2002-04-05 2004-02-05 Stanley Fastening Systems, L.P. Pneumatic tool with as-cast air signal passage
US7204402B2 (en) * 2002-04-05 2007-04-17 Stanley Fastening Systems, L.P. Pneumatic tool with as-cast air signal passage
US20070175942A1 (en) * 2003-04-04 2007-08-02 Stanley Fastening Systems, L.P. Pneumatic tool with as-cast air signal passage
US7926690B1 (en) * 2007-06-13 2011-04-19 Tippmann Sr Dennis J Combustion powered driver
US20110073631A1 (en) * 2007-06-13 2011-03-31 Tippmann Industrial Products, Inc. Combustion powered driver
US20100263975A1 (en) * 2007-10-19 2010-10-21 William Ernest Taylor Vallance Improvements in Movement Controls
EP2359013A1 (de) * 2008-12-19 2011-08-24 Väderstad-Verken Aktiebolag Vorrichtung an einem hydraulischen zylinder
EP2359013A4 (de) * 2008-12-19 2013-07-10 Vaederstad Verken Ab Vorrichtung an einem hydraulischen zylinder
US9004338B2 (en) * 2008-12-24 2015-04-14 Globalforce Ip Limited Adjustable dose chamber
US20110226836A1 (en) * 2008-12-24 2011-09-22 Hamish William Hamilton Adjustable dose chamber
US8579040B2 (en) 2009-10-14 2013-11-12 Daniel D. Sedmak Power-assisted garden tools
US20110083865A1 (en) * 2009-10-14 2011-04-14 Sedmak Daniel D Power-Assisted Garden Tools
CN105179019A (zh) * 2015-08-07 2015-12-23 鞍钢建设集团有限公司 一种用于水下自启的气压动力装置及自启方法
WO2018070881A1 (en) * 2016-10-11 2018-04-19 S-Gun Limited A pneumatic or hydraulic mechanism
CN109964048A (zh) * 2016-10-11 2019-07-02 S-加恩有限公司 气动或液压机构
CN109964048B (zh) * 2016-10-11 2021-08-20 S-加恩有限公司 气动或液压机构
US11242873B2 (en) 2016-10-11 2022-02-08 S-Gun Limited Pneumatic or hydraulic mechanism
US11818973B1 (en) 2020-05-12 2023-11-21 Daniel D. Sedmak Garden tiller utilizing an impact motor

Also Published As

Publication number Publication date
ES320363A1 (es) 1966-05-16
CH448754A (de) 1967-12-15
GB1087180A (en) 1967-10-11
SE311873B (de) 1969-06-23
DE1576158B1 (de) 1972-02-03

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