US3766990A - Low torque automatic screwdriver - Google Patents

Low torque automatic screwdriver Download PDF

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Publication number
US3766990A
US3766990A US00151329A US3766990DA US3766990A US 3766990 A US3766990 A US 3766990A US 00151329 A US00151329 A US 00151329A US 3766990D A US3766990D A US 3766990DA US 3766990 A US3766990 A US 3766990A
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US
United States
Prior art keywords
sear
drive end
clutch
screwdriver according
powered screwdriver
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
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US00151329A
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English (en)
Inventor
R Eckman
J Mitchell
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.)
Dresser Industries Inc
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Dresser Industries Inc
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Publication date
Application filed by Dresser Industries Inc filed Critical Dresser Industries Inc
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    • 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

Definitions

  • Powered screwdrivers of various types and capacities are well-known and have been commercially used for many years.
  • Popular among consumers of such tools are those specifically adapted to interrupt the power supply for automatic shutoff in contrast to those which slip or ratchet on encountering a turning resistance of preset torque value.
  • Marketed tools exemplifying the shutoff type are disclosed in U.S. Pat. Nos. 2,964,151; 2,986,052; and 3,242,996, all of which have met with a large measure of commercial success.
  • This invention relates to pneumatically powered screwdrivers of the automatic shutoff type suitable for low torque conditions of use. More specifically, the invention relates to such low torque screwdrivers capable of at least medium operating speeds on the order'of about 2,000 rpm and above while essentially retaining the compactness and light weight features previously characteristic of such tools. This is obtained in accordance herewith by means of a novel clutch-cutoff construction connecting the motor output to the drive bit.
  • the clutch provides positive torque responsive engagement and disengagement which is substantially insensitive to speed at which the tool is operative. Without speed sensitivity, previously imposed speed limitations are overcome thereby extending the operational speed range for which such tools can be constructed.
  • FIG. 1 is a longitudinal view partially in section of a tool in inoperative relation incorporating the construction hereof;
  • FIG. 2 is a fragmentary longitudinal section view of the tool of FIG. 1 in its operative relation;
  • FIG. 3 is an enlarged longitudinal view partially in section of the clutch mechanism
  • FIG. 4 is an enlarged longitudinal fragmentary section through the tool drive corresponding to the inoperative relation of FIG. 1;
  • FIG. 5 is a sectional elevation viewed substantially along the lines of 55 of FIG. 4;
  • FIG. 6 is a sectional elevation viewed substantially along the lines 6--6 of FIG. 4;
  • FIG. 7 ' is an enlarged longitudinal fragmentary section through the tool drive corresponding to the operative relation of FIG. 2;
  • FIG. 8 is a sectional elevation viewed substantially along the lines 8-8 of FIG. 7;
  • FIG. 9 is an enlarged longitudinal fragmentary section through the tool drive in its post-torqued operative relation corresponding to FIG. 2;
  • FIG. 10 is a sectional elevation viewed substantially along the lines 10-l0 of FIG. 9;
  • FIG. 11 is an enlarged isometric view of the cutoff sear as enclosed within the dashed outlined in FIG. 4;
  • FIG. 12 is a partial plan view as seen from the position l2-l2 of FIG. 1.
  • the tool hereof is generally comprised of an elongated longitudinal housing formed of a rear section 11 enclosing the drive components and telescopically threaded to a front section 13 enclosing the work engaging and torque responsive elements. Within the latter is included a screwdriver bit or the like 14 secured in output shaft 17 for rotationally driving a screw or other similar type fastener element 15. It is understood of course that various forms of bits can be substituted for that shown as required, including but not limited to Phillips head, Allen head, socket, etc.
  • Tool drive is furnished by a conventional vane-type pressure fluid motor (not shown) contained in housing section 11 and operationally supplied with high pressure air received at inlet 18. Output from the motor is transmitted to screwdriver bit 14 via an intermediate clutch mechanism 19 to be described.
  • Tool actuation is initiated by a guide piece 22 adapted to engage screw 15 and slideably contained within the necked-down work end 23 of housing section 13.
  • a key 24 which rotationally interlocks the guide piece to work end 23, but permits slideable inward movement thereof. Inward movement is opposed by coil spring 26 and is limited in both directions to the extent afforded by longitudinal key slot 25 as can be best understood by contrasting the guide piece relation in FIGS. 1 and 2.
  • Rearward guide piece displacement permits bit 14 to engage screw '15. Since the bit shank 36 is detachably mounted via a ball detent 37 to the full depth of output shaft bore 38, further rearward movement carries with it clutch 19 and a throttle rod 40 for admitting air received at inlet 18.
  • air inlet 18 is contained in a connector 28 screw threaded to the rear of housing section 1 1 andfit pressure tight with respect thereto by means of an annular o-ring seal 29. Fluid pressure admitted through the connector is communicated into an enclosed chamber 30 whereat it is exposed to the back face of conically shaped throttle and shut-off valve 31.
  • the shut-off valve cooperates with an annular seat 32 for controlling fluid flow into a chamber 33 which in turn feeds passage 34 for supplying air into a motor inlet port 35.
  • Opening and closing of valve 31 is governed by axially slidable throttle rod 40 diametrically enlarged at 41, reduced again at 42 and enlarged again at 43. The latter end is received in axial bore 48 of output drive shaft 17 subjecting the rod to urgingin the other direction by compressed coil spring 50 in chamber 30 acting against the back face of valve 31.
  • Air exhaust is through muffler '44 and exhaust ports 45.
  • the motor is connected to a planetary gear train (not shown) the output of which is rerpresented by a shaft 51 journalled in ball bearing 52.
  • Shaft 51 includes a central axial bore 53 of hexagonal cross section in which to slidably receive a hexagonal input stub shaft 54 of clutch 19 for a rotational driving interlock there between.
  • Clutch output is through radially extending annular flange 58 integral with a rearward reduced diameter portion 59 of shaft 7 19.
  • the latter shaft portion is further reduced at its terminal end 60 at which it is formed of polygonal cam acting cross section, preferably square, extending inward of clutch 19 for reasons as will be understood.
  • Clutch 19 for rotatable coupling to output shaft 17, includes a body 63 having a central bore 64 through which to slideably receive section 41 of throttle rod 40.
  • a counterbore 65 receives output shaft section 59 to which it is axially coupled but rotatably free by means of a plurality of small diameter balls 66.
  • the balls are adapted to seat between annular shaft groove 67 and corresponding annular clutch groove 68 and are supplied for that purpose through a radial bore 69 whereat they are retained by means of an encircling spiral type spring retainer 70.
  • the leftward end of clutch 19 (as viewed in the drawings) includes a cam 74 having a plurality of lobes 75.
  • the lobes extend axially leftward facing toward shaft 17 at angularly displaced intervals radially outward of the shaft.
  • the cam is axially recessed at 76 to receive a hardened steel ball 77.
  • each recess forms a rise 78 of gradual pitch effective for screw tightening and an opposite rise 79 of comparatively steeper pitch effective for reverse tool operation as for untightening of a screw or the like.
  • Balls 77 in turn, extend axially inward of a plurality of radially open slots 82 formed in shaft flange 58 and angularly matched to the location of cam recesses 76.
  • a cup shaped ball cage-retainer 83 constantly urged axially rearward by means of a coil spring 84.
  • the spring is axially compressed between a follower 85 acting through thrust bearing 86 against the back side of retainer 83 and an opposite follower 87 (FIG. 1) axially slideable but rotationally secured to shaft 17 by means of opposite keys 88.
  • a radially movable sear or release pin 91 Concomitantly operative with of clutch 19 but operably independent disengagement thereof for effecting power interruption is a radially movable sear or release pin 91 (see also FIG. 11) in a radially extending cylindrical cavity of body 63.
  • the scar is generally cylindrical, geometrically formed as to place its centroid location 100 radially displaced'from the rotational tool axis 101.
  • the pin includes a relatively small top mass 102 and a comparative larger bottom mass 103.
  • the pin includes side faces 92 and 93 and a lateral bore 94 axially parallel to tool axis 101 and of diameter sufficient when appropriately positioned to slideably pass throttle rod diameters 41 and 42.
  • Inward of face 92 is a slot cutout 95 v-shaped at its top forming an apex 96 being urged against the side flat 61 of shaft end 60 by means of compressed coil spring 98.
  • Valve 31 and rod 40 remain in the closed position while clutch 19 remains rearward.
  • springs 26, 49 and 98 restore the components to their original'startup relation of FIGS. 1 and 4. Fluid pressure aided by spring 50 holds valve 31 against seat 32 while spring 49 urges guide piece 22 and consequently clutch 19 leftward allowing all components to reset.
  • an adjustment nut 106 as seen in FIGS. 1 and 12 screw threaded onto shaft 17.
  • Nut 106 has a serrated radial end 107, facing toward angularly displaced pockets 108 in the back side of spring follower 87. Contained in the uppermost pocket is a hardened steel ball 109 adapted to normally seat in a serration valley 110 of the nut face.
  • a slot 112 formed in housing 13 in the vicinity of nut 106 access is provided thereto whereby a Phillips screwdriver end or the like can be inserted into an adjacent nut serration. Rotating the nut in either direction will threadably advance or withdraw the nut along shaft 17.
  • a rotatably displaceable spring clip 113 normally covers slot 112 and can be rotated for exposing nu't 106 to render adjustment in the manner just described.
  • the tool is supplied by flexible conduit or the like with high pressure air from a suitable source connected to inlet 18.
  • a fastener such as a screw 15
  • the tool is automatically centered on the fastener while guide piece 22 is caused to slide axially rearward for the fastener to be engaged by screwdriver bit 14.
  • screwdriver bit 14 Continued pressing engagement therebetween forces the screwdriver bit rearward carrying with it drive shaft 17, clutch 19 and the operating components secured thereto.
  • the same rearward movement likewise forces throttle valve rod 40 rearward to open valve 31 whereby fluid pressure in chamber 30, is admitted to chamber 33, passage 34 and motor port 35 for energizing the motor.
  • a powered screwdriver comprising in combination:
  • an air motor having an inlet at which to receive a source of high pressure supply air
  • a clutch operative to couple the output of said motor to said drive end and operative to effectively uncouple said drive end from said motor output at an encountered fastener turning resistance corresponding to a torque of predetermined value
  • disconnect means operative concomitantly and in parallel with the uncoupling of said clutch to effect interruption of air supply to said motor, said disconnect means including:
  • shutoff valve in said air inlet adapted to open and close the air supply to said motor
  • sear means movable radially relativeto the axis of tool rotation between a first position-effectively cocking said throttle rod against movement in a direction for closing said valve and a second position enabling said rod movement for closing said valve;
  • first cam means on said drive end operably inde pendent of the operation of said clutch for shifting said sear means from said first to said second position.
  • a powered screwdriver according to claim 1 in which the centroid of said sear is displaced from the axis of tool rotation whereby rotational forces aid to maintain said sear in said first position.
  • a powered screwdriver according to claim 2 in which said sear is supported transversely intersecting the axis of said tool with its centroid definitively located to one side of said axis and there is included biasing means acting against said sear directionally of said centroid urging the sear into said first position.
  • a powered screwdriver according to claim 3 in which said cam means is rotationally supported on the axis of said tool and includes a plurality of lobes displaced at angular intervals about its periphery, at least one of said.lobes being effective in concomitantly with uncoupling of said clutch to radially shift said sear means from said first to said second positions in opposition to said biasing means.
  • a powered screwdriver according to claim 4in which said throttle rod is supported on the axis of said tool extending through an axially parallel bore in said sear means, said bore being located radially offset with respect to said tool axis while said sear means is in said first position to effect cocking of said throttle rod and is shifted to relatively approach axial coincidence when said sear means is shifted to said second position for uncocking of said throttle rod.
  • a powered screwdriver according to claim 5 in which said throttle rod includes a radial wall adjacent said sear means, and a wall segment of said sear means contiguous to said bore axially interferes with said throttle rod wall to effect said throttle rod cocking.
  • a powered screwdriver including a housing supportably enclosing said motor, said drive end, said clutch and said disconnect means, and in which said drive end is axially slideable inward of said housing in response to a pressing work engagement against a fastener to be driven and said throttle rod is axially moveable in conjunction with said drive end to effect opening of said shutoff valve.
  • a powered screwdriver according to claim 7 in which said throttle rod operatively moves inwardly toward said drive end to effect closing of said shutoff valve in response to shifting of said sear means to said second position.
  • a powered screwdriver including biasing means to operatively effect a driving relation between said motor, said drive end, said clutch and said disconnect means at the onset of work engagement with a fastener and to restore said driving relation on post-torqued removal from work engagement with the-fastener.
  • a powered screwdriver according to claim 1 in which said clutch comprises a first annular member having a plurality of lobes displaced at angular intervals about a radial face of said member with adjacent of said lobes defining an axial recess therebetween, a second annular member having a plurality of axial cutouts circumferentially opposite the recesses of said first member, interfitting means extending between each of said opposite recess and cutout to effect a rotational coupling relation between said first and second members, biasing means acting to urge one of said members toward the other for maintaining said coupling relation and second cam means operative to uncouple said first and second members in response to encountering of said predetermined torque value by said drive end.
  • Apowered screwdriver according to claim It) in which said interfitting means comprise balls and said second cam means is defined by a surface pitch merging at least one common end of said recesses to its contiguous lobe. 7
  • a powered screwdriver according to claim 11 in which said first annular member'is operatively connected to said motor and said second annular member is operatively connected to said drive end.
  • a powered screwdriver according to claim 11in which the centroid of said sear is displaced from the axis of too] rotation whereby rotational forces aid to maintain said sear in said first position.
  • a powered screwdriver according to claim 13 in which said sear is supported transversely intersecting the axis of said tool with its centroid definitively located to one side of said axis and there is included second biasing means acting against said sear directionally of said centroid urging the sear into said first position.
  • a powered screwdriver according to claim l4 in which said first cam means is rotationally supported on the axis of said tool and includes a plurality of lobes displaced at angular intervals about its periphery, at least one of said lobes being effective concomitantly with uncoupling of said clutch to radially shift said sear means from said first to said second positions in opposition to said second biasing means.
  • a powered screwdriver including a housing supportably enclosing said motor, said drive end, said clutch and said disconnect means, and in which said drive end is axially slideable inward of said housing in response to a pressing work engagement against a fastener to be driven, and said throttle rod is axially moveable in conjunction with said drive end to effect opening of said shutoff valve.
  • a powered screwdriver according to claim 16 in which said throttle rod operatively moves inwardly toward said drive end to effect closing of said shutoff valve in response to shifting of said sear means to said second position.
  • a powered screwdriver including biasing means to operatively effect a driving relation between said motor, said drive end, said clutch and said disconnect means at the onset of work engagement with a fastener and to restore said driving relation on post-torqued removal from work engagement with the fastener.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Details Of Spanners, Wrenches, And Screw Drivers And Accessories (AREA)
US00151329A 1971-06-09 1971-06-09 Low torque automatic screwdriver Expired - Lifetime US3766990A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US15132971A 1971-06-09 1971-06-09

Publications (1)

Publication Number Publication Date
US3766990A true US3766990A (en) 1973-10-23

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Application Number Title Priority Date Filing Date
US00151329A Expired - Lifetime US3766990A (en) 1971-06-09 1971-06-09 Low torque automatic screwdriver

Country Status (8)

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US (1) US3766990A (fr)
JP (1) JPS5335320B1 (fr)
CA (1) CA955086A (fr)
DE (1) DE2228116C2 (fr)
FR (1) FR2141208A5 (fr)
GB (1) GB1332275A (fr)
IT (1) IT958255B (fr)
SE (1) SE398059C (fr)

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3918533A (en) * 1972-07-26 1975-11-11 Weber Schraubautomaten Screwdriver
US4071092A (en) * 1977-03-09 1978-01-31 Chicago Pneumatic Tool Company Pneumatic screwdriver with torque responsive shut-off
US4078618A (en) * 1976-03-15 1978-03-14 Gardner-Denver Company Torque controller shutoff mechanism
US4114699A (en) * 1976-01-22 1978-09-19 Licentia Patent-Verwaltungs-Gmbh Pneumatic rotary hammer device
US4154308A (en) * 1977-10-25 1979-05-15 Dresser Industries, Inc. Low torque automatic screwdriver
US4318334A (en) * 1980-03-20 1982-03-09 Carrier Corporation Torque control for a fluid operated motor
US4576270A (en) * 1983-02-28 1986-03-18 The Aro Corporation Torque control and fluid shutoff mechanism for a fluid operated tool
US4875528A (en) * 1989-02-13 1989-10-24 Allen-Bradley Company, Inc. Torque control actuator
US4951756A (en) * 1989-05-16 1990-08-28 Chicago Pneumatic Tool Company Torque control screwdriver
US5054588A (en) * 1990-08-31 1991-10-08 The Aro Corporation Torque sensing automatic shut-off and reset clutch for screwdrivers, nutsetters and the like
US5129465A (en) * 1989-03-28 1992-07-14 Atlas Copco Tools Ab Screw tightening power tool
US5156244A (en) * 1990-08-31 1992-10-20 The Aro Corporation Torque sensing automatic shut-off and reset clutch for screwdrivers, nutsetters and the like
US5738177A (en) * 1995-07-28 1998-04-14 Black & Decker Inc. Production assembly tool
WO2000078490A2 (fr) * 1999-06-18 2000-12-28 Cooper Technologies Company Outil a avance constante pourvu d'un embrayage
US20120080285A1 (en) * 2010-10-01 2012-04-05 Ho-Tien Chen Clutch device for a screw driver
US9308636B2 (en) 2012-02-03 2016-04-12 Milwaukee Electric Tool Corporation Rotary hammer with vibration dampening
US9718159B2 (en) 2013-11-04 2017-08-01 Seagate Technology Llc Adaptive fastener access tool

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5549537A (en) * 1978-10-04 1980-04-10 Nissan Motor Co Ltd Fuel shut-off device
US4488604A (en) * 1982-07-12 1984-12-18 The Stanley Works Torque control clutch for a power tool
GB2149465B (en) * 1983-11-15 1987-09-09 Desoutter Ltd A pneumatically operated power tool
JPS60247033A (ja) * 1984-05-21 1985-12-06 Japan Electronic Control Syst Co Ltd 内燃機関の電子制御燃料噴射装置
CN108177115B (zh) * 2018-03-20 2024-02-06 武汉多可特医疗器械有限公司 一种自夹紧螺钉电动螺丝刀

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3082742A (en) * 1960-05-09 1963-03-26 Ingersoll Rand Co Torque tool control
US3275116A (en) * 1964-10-12 1966-09-27 Airetool Mfg Company Air powered tool with overload cutoff
US3612236A (en) * 1969-06-27 1971-10-12 Atlas Copco Ab Threaded fastener-setting tool with torque release means

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2986052A (en) * 1958-10-27 1961-05-30 Reed Roller Bit Co Predetermined torque responsive hand tool
DE1503022A1 (de) * 1962-03-03 1969-10-30 Reed Roller Bit Co Durch ein Druckmedium betaetigtes Werkzeug
US3354754A (en) * 1965-11-16 1967-11-28 Chicago Pneumatic Tool Co Nut-runner with reverse rotation brake
US3477521A (en) * 1967-10-05 1969-11-11 Aro Corp Automatic power tool

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3082742A (en) * 1960-05-09 1963-03-26 Ingersoll Rand Co Torque tool control
US3275116A (en) * 1964-10-12 1966-09-27 Airetool Mfg Company Air powered tool with overload cutoff
US3612236A (en) * 1969-06-27 1971-10-12 Atlas Copco Ab Threaded fastener-setting tool with torque release means

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3918533A (en) * 1972-07-26 1975-11-11 Weber Schraubautomaten Screwdriver
US4114699A (en) * 1976-01-22 1978-09-19 Licentia Patent-Verwaltungs-Gmbh Pneumatic rotary hammer device
US4078618A (en) * 1976-03-15 1978-03-14 Gardner-Denver Company Torque controller shutoff mechanism
US4071092A (en) * 1977-03-09 1978-01-31 Chicago Pneumatic Tool Company Pneumatic screwdriver with torque responsive shut-off
US4154308A (en) * 1977-10-25 1979-05-15 Dresser Industries, Inc. Low torque automatic screwdriver
US4318334A (en) * 1980-03-20 1982-03-09 Carrier Corporation Torque control for a fluid operated motor
US4576270A (en) * 1983-02-28 1986-03-18 The Aro Corporation Torque control and fluid shutoff mechanism for a fluid operated tool
US4875528A (en) * 1989-02-13 1989-10-24 Allen-Bradley Company, Inc. Torque control actuator
US5129465A (en) * 1989-03-28 1992-07-14 Atlas Copco Tools Ab Screw tightening power tool
US4951756A (en) * 1989-05-16 1990-08-28 Chicago Pneumatic Tool Company Torque control screwdriver
US5054588A (en) * 1990-08-31 1991-10-08 The Aro Corporation Torque sensing automatic shut-off and reset clutch for screwdrivers, nutsetters and the like
US5156244A (en) * 1990-08-31 1992-10-20 The Aro Corporation Torque sensing automatic shut-off and reset clutch for screwdrivers, nutsetters and the like
US5738177A (en) * 1995-07-28 1998-04-14 Black & Decker Inc. Production assembly tool
WO2000078490A2 (fr) * 1999-06-18 2000-12-28 Cooper Technologies Company Outil a avance constante pourvu d'un embrayage
US6196772B1 (en) 1999-06-18 2001-03-06 Cooper Technologies Company Positive feed tool having a clutch
WO2000078490A3 (fr) * 1999-06-18 2002-10-03 Cooper Technologies Co Outil a avance constante pourvu d'un embrayage
US20120080285A1 (en) * 2010-10-01 2012-04-05 Ho-Tien Chen Clutch device for a screw driver
US9308636B2 (en) 2012-02-03 2016-04-12 Milwaukee Electric Tool Corporation Rotary hammer with vibration dampening
US10195730B2 (en) 2012-02-03 2019-02-05 Milwaukee Electric Tool Corporation Rotary hammer
US9718159B2 (en) 2013-11-04 2017-08-01 Seagate Technology Llc Adaptive fastener access tool

Also Published As

Publication number Publication date
GB1332275A (en) 1973-10-03
SE398059C (sv) 1979-05-14
CA955086A (en) 1974-09-24
FR2141208A5 (fr) 1973-01-19
DE2228116C2 (de) 1983-10-13
JPS5335320B1 (fr) 1978-09-26
IT958255B (it) 1973-10-20
DE2228116A1 (de) 1972-12-28
SE398059B (sv) 1977-12-05

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