US3315754A - Torque limiting apparatus - Google Patents

Torque limiting apparatus Download PDF

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Publication number
US3315754A
US3315754A US412023A US41202364A US3315754A US 3315754 A US3315754 A US 3315754A US 412023 A US412023 A US 412023A US 41202364 A US41202364 A US 41202364A US 3315754 A US3315754 A US 3315754A
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US
United States
Prior art keywords
valve
shaft
motor
passageway
air
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US412023A
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English (en)
Inventor
Holdo Jan Kristian
Westerlund Bengt Arvid
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Atlas Copco AB
Original Assignee
Atlas Copco AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Atlas Copco AB filed Critical Atlas Copco AB
Priority to US412023A priority Critical patent/US3315754A/en
Priority to NL6515000A priority patent/NL6515000A/xx
Priority to BE672512D priority patent/BE672512A/xx
Application granted granted Critical
Publication of US3315754A publication Critical patent/US3315754A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D43/00—Automatic clutches
    • F16D43/02—Automatic clutches actuated entirely mechanically
    • F16D43/20—Automatic clutches actuated entirely mechanically controlled by torque, e.g. overload-release clutches, slip-clutches with means by which torque varies the clutching pressure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
    • B25B23/00—Details of, or accessories for, spanners, wrenches, screwdrivers
    • B25B23/14—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers
    • B25B23/145—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers specially adapted for fluid operated wrenches or screwdrivers
    • B25B23/1453—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers specially adapted for fluid operated wrenches or screwdrivers for impact wrenches or screwdrivers

Definitions

  • This invention relates generally to torque limiting apparatus for limiting the maximum torque transmitted from a rotary driving motor to an element rotated by the motor. More specifically the invention relates to torque limiting apparatus applicable to power wrenches of the rotary as well as of the impacting type.
  • control of the final torque applied to the fasteners is important for the provision of uniform tightening and maximum strength in the connection.
  • the rotated element such as the tool shaft or head of a power Wrench
  • the tool head together with the fastener during the continuously repeated blows turns a certain angle for each blow and this angle decreases successively from blow to blow with increasing tightness.
  • tool head or fastener thus evidently is a measure for the torque applied to the fastener and can be used for purposes of limiting the final torque to a predetermined value.
  • a further object of the invention is to provide a torque limiting apparatus of the above character in which the measuring is performed continuously by pneumatic means and the cut off of power is controlled by means responsive to the behaviour of the pneumatic measuring means.
  • FIG. 1 is a longitudinal sectional view through a power wrench incorporating the apparatus according to the invention
  • FIG. 2a is a sectional view on the line 22 in FIG. 1
  • FIG. 2b is a sectional view through a modified embodiment of the automatic control valve forming part of the wrench shown in FIG. 1
  • FIG. 2c is a measuring instrument coupled to a line connecting the elements shown in FIGS. 2:: and 2b
  • FIG. 3 shows a sectional view on the line 33 in FIG. 1.
  • the numeral designates a rotary pressure fluid driven power wrench which may be of any suitable conventional type with or without impact action.
  • an impact wrench similar to the one disclosed in US. patent application Ser. No. 184,013, now Patent No. 3,179,219 to Kardn but the invention is not restricted to power wrenches of that particular type. Accordingly, there is provided in the housing 11 of the power wrench 10 a reversible rotary air motor 12 having radial driving vanes 13 on a rotor 14, the rotational direction of which is controlled by the usual reversing valve 15.
  • the reversing valve 15 and motor 12 are supplied with compressed air through a passage 16 controlled by a control valve 17 which can be operated manually by a trigger 18 on the handle 19 of the power wrench 10.
  • An air-nipple 20 upstream of the control valve 17 receives compressed air from a supply hose, not shown, connected thereto.
  • the rotor 14 of the air motor 12 is coupled for rotating a hammer 21 journalled in the housing 11.
  • the hammer 21 is supported at its rear end on a splined projection of the rotor 14 while its forward end slides on the tool shaft or anvil 22 of the power wrench.
  • the rear end of the shaft 22 is supported inside of the hammer 21 While its middle portion is journalled in the front end of the housing 11.
  • the outer end of the shaft 22 has the usual square end 23 for removably carrying tools engageable with the fasteners to be driven.
  • an impact dog 24 pivotally journalled inside of the hammer 21 delivers impacts to the shaft 22 when the latter meets sufiicient resistance to rotation.
  • the impact dog 24 is moved to impact delivering position.
  • FIG. 3 by a cam 25 on the shaft 22 cooperating with the trailing edge of the impact dog 24, while a torsion spring 26 extending centrally and longitudinally of the Wrench 10, in the position depicted in FIG. 3 cooperates with a pin 49 on the impact dog 24 so that the leading edge thereof is pivoted out of engagement with the shaft 22 and the impact dog 24 will be able to rotate in unison with the hammer 21 around the arrested shaft 22 for producing the next impact.
  • the apparatus for limiting the application of torque to the fasteners driven by the power wrench 10 includes an automatic control valve 27 in a valve case 31 upstream of the manual control valve 17.
  • the valve 27 is a fiat disk valve cooperating with a circular valve seat 28 in the passageway 29 connecting the nipple 20 with the manual control valve 17.
  • the automatic control valve 27 has a projecting piston end 3! ⁇ which is slidably but tightly received in a bore in the valve case 31 whereby the control valve 27 is guided in its movements between a cut-off and an open position.
  • a washer 34 The opposite end of the spring 33 is supported by a washer 34, the axial position of which in the chamber 32 can be adjusted by means of a set screw 35, which extends through the wall of the valve case 31 and is in threaded engagement therewith.
  • a branch passage 36 From the passageway 29 a branch passage 36 leads to the chamber 32.
  • the air flow through the passage 36 can be controlled by a needle valve 37.
  • the chamber 32 is connected to the forward end of the power wrench 10 by a conduit 38 communicating with a bore 39 disposed preferably perpendicularly to the surface of the shaft 22.
  • the bore 3? is provided in a fitting 4t), FIG. 2a, connected to the housing 11 as by screws 41.
  • a nozzle body 42 is slidable in the bore 39 and has an O-ring therearound for providing tightness between the nozzle 42 and the bore 39.
  • the nozzle 42 is preferably made of plastic material offering small frictional resistance to sliding motion against metal and sliding in collector brush manner on the periphery of the shaft 22.
  • a bore 43 extends axially through the nozzle 42.
  • a helical spring 44 is interposed between a shoulder in the bore 39 and the nozzle 42 for urging the latter against the shaft 22.
  • a series of axial grooves 45 are provided in evenly spaced disposition circumferentially on the shaft 22 and 3 the portion thereof forming the path of movement of the nozzle 42 during rotation of the shaft 22. Between the grooves 45 peripheral boom portions 46 of the shaft 22 remain undisturbed.
  • the passage 16 upstream of the reversing valve 15 is connected by a conduit 50 to the chamber 32 in the valve case 31.
  • a spring pressed check valve 51 opening for flow in the direction from the chamber 32 to the passageway 16 is provided in the conduit 50 and the valve case 31.
  • a bleed hole 52 is provided in the valve disk of the automatic control valve 27 whereby air can bleed past the valve 27 in the cut-off position thereof.
  • the valve disk of the automatic control valve 27 is disposed at a relatively small distance from the seat 28 in the open position of the valve 27 in such manner as to create a pressure differential across the valve disk assisting in closing the valve 27 at the desired instant with a snap action.
  • the compressed air trapped in the passage 16 expands upon closing of the automatic valve 27 through the air motor 12.
  • the falling pressure in the passage 16 results in that the check valve 51 in the conduit 50 is opened whereupon the chamber 32 is exhausted to atmosphere via the motor 12.
  • air leaking from the passageway 29 through the bleed hole 52 in the valve 27 will likewise leak out to atmosphere through the passage 16 and the motor 12 so that the automatic control valve 27 will remain closed.
  • the air issuing through bleed hole 52 will rapidly equalize the pressures at opposite sides of the valve disk of the valve 27, whereupon the pressure in the passageway 29 will return the valve 27 to open position against the action of the spring 33.
  • the chamber 32 is exhausted to the atmosphere by the conduit 50 and the motor 12 or by the conduit 38 when one of the grooves 45 registers with the bore 43 in the nozzle 42.
  • the opening force acting on the valve 27 is therefore not counteracted by pressure in the chamber 32.
  • the power wrench It) is thus again in starting position and ready for the next tightening cycle.
  • the modified automatic control valve shown in FIG. 2b has an axial central passage 53 through the piston end 30 and through a tubular extension 54 coaxially thereon.
  • the extension 54 is tightly but slidably received in a partition 55 forming the rear wall of the air chamber 32 in the valve case 56.
  • a nipple 57 screwed to the valve case 56 and disposed coaxially with the automatic valve 27 compressed air enters from the supply hose, not shown, and passes along the central passage 53 through radial apertures 58 to the rear of the valve disk included in the automatic valve 27.
  • the bleed hole 52 is in this instance provided centrally in the valve disk.
  • a needle valve 37 provides a means for adjusting the desired maximum torque at which the power to the tool is to be cut off.
  • a pressure gauge 59 may be connected to the conduit 38 whereby adjustment of the torque limiting apparatus is made more easy when using the spring 33 for pressure adjustments.
  • the gauge 59 can also be used for indicating the moment at which the operator has to interrupt the supply of power purely manually for reaching the desired value of the final torque.
  • the pressure gauge 59 obviously can be used as an indicator of the angular velocity of the shaft 22.
  • the disk of the automatic valve 27, FIG. 2b will be omitted so that driving air constantly can pass to the driving motor of a rotary shaft 22 arranged as indicated in FIG. 2a.
  • the readings on the gauge 59 can be calibrated to indicate the angular velocity of the shaft 22 whereby the device according to FIGS. 2a-2c can be used for direct measurement of angular velocity.
  • a torque limiting apparatus comprising in combination a rotary motor, a member connected to said motor for being rotated thereby, means for measuring the angular displacement per unit of time of said member, and automatic means for cutting of the supply of power to said motor, said measuring means operative upon the decrease of said angular displacement per unit of time to a predetermined value to cause actuation of said automatic mfieans whereby the supply of power to said motor is cut 0 2.
  • an apparatus for limiting the maximum torque transmitted from a compressed air driven motor to an element rotated thereby the combination which comprises said motor and element, an air line connected to said motor for supplying compressed air thereto, a drive shaft connected between said motor and element, pneumatic measuring means cooperating with said shaft in a manner to build up a pressure in said means which inrreases with decreasing angular displacement per unit of time of said shaft, a valve in said air line for cutting off the air supply to said motor, and means connected to said valve and operative upon the development of a predetermined pressure in said measuring means to cause actuation of said valve whereby the supply of air to said motor is cut off.
  • a power wrench comprising a housing, a rotary motor in said housing, a tool head connected to said motor for being rotated thereby and protruding from said housing, a shaft included in said tool head, a series of axial grooves in evenly spaced disposition circumferentially on said shaft, a nozzle nonrotatably supported in said housing and having an outlet orifice adjacent the periphery of said shaft and traversing said grooves and the portions of said shaft therebetween during rotation of said tool head, said portions obstructing flow through said orifice when in registry therewith, a passageway communicating with said nozzle and orifice, means for constantly supplying air under pressure to said passageway at a lesser rate than issuing through said orifice when said orifice registers with said grooves, and automatic means responsive to the development of a predetermined pressure in said passageway as a result of the obstruction offered by said portions during rotation of said tool head and shaft for automatically cutting ofl. the supply of power to said motor.
  • a power wrench as set forth in claim 3 in which said nozzle is axially slidably supported in said housing and in which there are provided means for biasing the end of said nozzle carrying said orifice into sliding contact with said shaft and said portions thereon.
  • a power wrench as set forth in claim 3 in which there is provided an adjustable valve in said air supply means for adjustably controlling the air supply to said passageway.
  • a portable pneumatic power wrench comprising a rotary air motor, a shaft driven by said motor, a first passageway for supplying said motor with air under pressure for rotating said shaft, a valve seat in said first passageway, an automatic control valve in said first passageway upstream of said seat and movable between open and seated positions to admit or cut off the supply to said motor, resilient means urging said valve to seated position, a first surface on said valve exposed to pressure in said first passageway for maintaining said automatic valve in open position against the action of said resilient means, a second passageway branched ofi from said first passageway at a point upstream of said valve seat, a second surface on said valve opposed to said first surface and communicating with said second passageway, said second surface responsive to the development of a predetermined pressure in said second passageway for combining its action with the action of said resilient means to move said valve to seated position, and pneumatic means connected to said second passageway and receiving air under pressure therefrom, said pneumatic means being responsive to decrease of the angular displacement per unit of time of said shaft to
  • a power wrench as set forth in claim 6 having a manually operable control valve in said first passageway downstream of said seat, said control valve being movable between open and closed positions to admit or cut off the air supply to said motor, there being provided a bleed passage in parallel with said automatic valve in the closed position thereof for pressure equalization at opposite sides of said seat and for resetting said automatic valve to open position when said manually operable valve is closed.
  • a power wrench as set forth in claim 8 including a communication for connecting said second passageway with said first passageway at a point between said control valve and said motor, and a check valve in said communication for relieving the pressure in said second passageway when said manually operable valve is closed.
  • An impact wrench comprising a housing, a rotary air motor in said housing, a rotatable hammer in said housing connected to said motor, an anvil shaft rotatably journalled in said housing and carrying a tool head at one end thereof, said tool head protruding from said housing and having means thereon connectable to a threaded fastener to be driven, means for transmitting rotational blows from said hammer to said anvil shaft in response to said shaft meeting sufficient resistance to rotation of said fastener, said blows causing successively decreasing angular displacements of said anvil shaft with increasing resistance of said fastener, a passageway for supplying air under pressure to said motor for operating the same, an automatic valve controlling said passageway and movable between open and closed positions to admit or cut ofi the supply of air to said motor, and means responsive to the angular displacements per unit of time of said anvil shaft decreasing to a predetermined value for effecting the movement of said valve to closed position to stop said motor.
  • An impact wrench as set forth in claim 11 comprising a series of axial grooves in evenly spaced disposition circumferentially on said shaft, a nozzle nonrotatably su ported in said housing and having an outlet orifice adjacent said shaft for traversing said grooves and the portions of said shaft therebetween as a consequence of said angular displacements, said portions being in such proximity to said nozzle when in.
  • a device for measuring the angular velocity of a shaft rotated by power comprising a rotary shaft, a series of grooves in evenly spaced disposition circumferentially on said shaft, a nozzle non-rotatahly supported adjacent said shaft and having an outlet orifice supported to traverse said grooves and the portions of said shaft therebetween during rotation of said shaft, said portions obstructing flow through said orifice when in registry therewith, a passageway communicating with said nozzle and orifice, means for constantly supplying fluid under pressure to said passageway at a lesser rate than issuing through said orifice when said orifices register with said grooves, and a pressure gauge connected to said passageway to respond to pressure fluctuations therein thereby to indicate the angular velocity of said shaft and its fluctuations with rotational resistance.
  • a measuring device as set forth in claim 15 in which said nozzle is axially slidably supported in said housing and in which there are provided means for bias- 8 ing the end of said nozzle carrying said orifice into sliding contact with said shaft and said portions thereon.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Details Of Spanners, Wrenches, And Screw Drivers And Accessories (AREA)
US412023A 1964-11-18 1964-11-18 Torque limiting apparatus Expired - Lifetime US3315754A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US412023A US3315754A (en) 1964-11-18 1964-11-18 Torque limiting apparatus
NL6515000A NL6515000A (enExample) 1964-11-18 1965-11-18
BE672512D BE672512A (enExample) 1964-11-18 1965-11-18

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US412023A US3315754A (en) 1964-11-18 1964-11-18 Torque limiting apparatus

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BE (1) BE672512A (enExample)
NL (1) NL6515000A (enExample)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3407883A (en) * 1966-12-16 1968-10-29 Chicago Pneumatic Tool Co Pneumatic nut-runner with a differential pressure switch control
US3693726A (en) * 1970-09-17 1972-09-26 Daimler Benz Ag Tightening device for automatically tightening bolts and the like
US3976389A (en) * 1973-10-10 1976-08-24 Hollymatic Corporation Pressurized gas engine
US5180019A (en) * 1991-04-15 1993-01-19 Ingersoll-Rand Company Power tool having selectable inlet location
US5626198A (en) * 1995-04-26 1997-05-06 Atlas Copco Tools Pneumatic torque impulse tool
WO2003095151A1 (en) 2002-05-09 2003-11-20 Snap-On Incorporated Air auto shut-off mechanism for a pneumatic torque-applying tool
WO2010110714A1 (en) * 2009-03-25 2010-09-30 Atlas Copco Tools Ab Pneumatic power wrench with a exhaust air outlet unit

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS55164482A (en) * 1979-06-04 1980-12-22 Nippon Pneumatic Mfg Controller for torque of impact wrench
US5531279A (en) * 1994-04-12 1996-07-02 Indresco Inc. Sensor impulse unit

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1104233B (de) * 1959-12-17 1961-04-06 Licentia Gmbh Hydraulische Einrichtung zum Ausloesen eines Impulses beim Unterschreiten der Grenzdrehzahl eines rotierenden Drehteiles
US3136326A (en) * 1960-09-12 1964-06-09 Westinghouse Electric Corp Speed sensing apparatus
DE1176405B (de) * 1961-06-26 1964-08-20 Daume Regelarmaturen W Mit Druckmittel betriebener Drehzahlmesser
US3195655A (en) * 1960-12-02 1965-07-20 Atlas Copco Ab Method and apparatus for controlling the degree of tightness of bolts or nuts driven by an impact wrench
US3216252A (en) * 1962-10-29 1965-11-09 Johnson Service Co Fluid flow rate meters

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1104233B (de) * 1959-12-17 1961-04-06 Licentia Gmbh Hydraulische Einrichtung zum Ausloesen eines Impulses beim Unterschreiten der Grenzdrehzahl eines rotierenden Drehteiles
US3136326A (en) * 1960-09-12 1964-06-09 Westinghouse Electric Corp Speed sensing apparatus
US3195655A (en) * 1960-12-02 1965-07-20 Atlas Copco Ab Method and apparatus for controlling the degree of tightness of bolts or nuts driven by an impact wrench
DE1176405B (de) * 1961-06-26 1964-08-20 Daume Regelarmaturen W Mit Druckmittel betriebener Drehzahlmesser
US3216252A (en) * 1962-10-29 1965-11-09 Johnson Service Co Fluid flow rate meters

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3407883A (en) * 1966-12-16 1968-10-29 Chicago Pneumatic Tool Co Pneumatic nut-runner with a differential pressure switch control
US3693726A (en) * 1970-09-17 1972-09-26 Daimler Benz Ag Tightening device for automatically tightening bolts and the like
US3976389A (en) * 1973-10-10 1976-08-24 Hollymatic Corporation Pressurized gas engine
US5180019A (en) * 1991-04-15 1993-01-19 Ingersoll-Rand Company Power tool having selectable inlet location
US5626198A (en) * 1995-04-26 1997-05-06 Atlas Copco Tools Pneumatic torque impulse tool
WO2003095151A1 (en) 2002-05-09 2003-11-20 Snap-On Incorporated Air auto shut-off mechanism for a pneumatic torque-applying tool
US20030226674A1 (en) * 2002-05-09 2003-12-11 Putney Gordon A. Air auto shut-off
US6883617B2 (en) 2002-05-09 2005-04-26 Snap-On Incorporated Air auto shut-off
WO2010110714A1 (en) * 2009-03-25 2010-09-30 Atlas Copco Tools Ab Pneumatic power wrench with a exhaust air outlet unit
US8955614B2 (en) 2009-03-25 2015-02-17 Atlas Copco Industrial Technique Aktiebolag Pneumatic power wrench with an exhaust air outlet unit

Also Published As

Publication number Publication date
BE672512A (enExample) 1966-03-16
NL6515000A (enExample) 1966-05-20

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