SE1550487A1 - Low reaction power wrench - Google Patents

Low reaction power wrench Download PDF

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Publication number
SE1550487A1
SE1550487A1 SE1550487A SE1550487A SE1550487A1 SE 1550487 A1 SE1550487 A1 SE 1550487A1 SE 1550487 A SE1550487 A SE 1550487A SE 1550487 A SE1550487 A SE 1550487A SE 1550487 A1 SE1550487 A1 SE 1550487A1
Authority
SE
Sweden
Prior art keywords
stator
power wrench
rotor
spring
anyone
Prior art date
Application number
SE1550487A
Other languages
Swedish (sv)
Inventor
Danebergs Andris
Original Assignee
Atlas Copco Ind Technique 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 Ind Technique Ab filed Critical Atlas Copco Ind Technique Ab
Priority to SE1550487A priority Critical patent/SE1550487A1/en
Priority to PCT/EP2016/058319 priority patent/WO2016169844A1/en
Publication of SE1550487A1 publication Critical patent/SE1550487A1/en

Links

Classifications

    • 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
    • B25B23/147—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers specially adapted for electrically operated wrenches or screwdrivers
    • 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
    • B25B21/00—Portable power-driven screw or nut setting or loosening tools; Attachments for drilling apparatus serving the same purpose
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K1/00—Details of the magnetic circuit
    • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
    • H02K1/12—Stationary parts of the magnetic circuit
    • H02K1/18—Means for mounting or fastening magnetic stationary parts on to, or to, the stator structures
    • H02K1/185—Means for mounting or fastening magnetic stationary parts on to, or to, the stator structures to outer stators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K5/00—Casings; Enclosures; Supports
    • H02K5/26—Means for adjusting casings relative to their supports
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
    • H02K7/14—Structural association with mechanical loads, e.g. with hand-held machine tools or fans
    • H02K7/145—Hand-held machine tool
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K2213/00—Specific aspects, not otherwise provided for and not covered by codes H02K2201/00 - H02K2211/00
    • H02K2213/09—Machines characterised by the presence of elements which are subject to variation, e.g. adjustable bearings, reconfigurable windings, variable pitch ventilators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K5/00—Casings; Enclosures; Supports
    • H02K5/24—Casings; Enclosures; Supports specially adapted for suppression or reduction of noise or vibrations

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)
  • Details Of Spanners, Wrenches, And Screw Drivers And Accessories (AREA)

Abstract

A power wrench (10) including an electric motor (13) comprising a stator (14) and a rötor (15), a torque delivering output shaft (16) that is drivingly connected to the rötor (15), and a housing (11,17) in which the stator (14) is arranged. The stator (14) is rotatively arranged with respect to the housing (11,17) . A spring (19) may be arranged to urge the stator (14) towards an initial position.(Elected for publication: Fig. 1)

Description

Low reaction power wrench The invention relates to a power wrench that is adapted to yield a lowreaction torque. Specifically the invention relates to a handheldpower wrench in which the reaction forces experienced by an operator holding the tool during a tightening operation are reduced.
Background Power wrenches are industrially used to tighten joints, such as boltsscrews and nuts. A general desire for all types of power wrenches,especially handheld power wrenches is to keep the reaction forces that are produced during a tightening operation as low as possible.
Different techniques are known for keeping the reaction forces low.One manner of reducing reaction forces is to use a pulsating motion orto build up inertia in the power tool, wherein the produced inertiamay be delivered to the joint without the creation of any reaction forces.
These conventional methods have both advantages and drawbacks. Hence,there is room for improvements in the field of power wrenches with a low reaction force.
Summary of the invention An object of the invention is to provide new kind of power wrench with a low reaction force.
This object is achieved by the invention according to a first aspectwhich relates to a power wrench including: - an electric motor comprising a stator and a rotor, - a torque delivering output shaft that is drivingly connected tothe rotor, and - a housing in which the stator is arranged, wherein the stator is resiliently arranged with respect to the housing, and wherein at least one spring is arranged to urge the stator towards an initial position.
The invention provides a power wrench in which the reaction forcesexperienced by an operator holding the tool during a tighteningoperation are reduced in that the stator is allowed to rotate inside the housing of the power wrench.
In one specific embodiment the at least one spring acts in bothdirections and has a proportional spring force that is proportional to its angular displacement from the initial position.
In another specific embodiment the at least one spring acts in onlyone direction, whereas the stator is prevented from rotation in theopposite direction. Preferably the stator in such an embodiment is arranged to only rotate in the counter clockwise direction, i.e.
In yet another specific embodiment the at least one spring acts inboth directions and has a spring force that increases in a non-linearmanner with its angular displacement from the initial position. Thespring force may either increase progressively with its extension or in a decreasingly manner.
In yet another specific embodiment at least one end stop is arranged to limit the rotation of the stator.
In one specific embodiment the rotor is rigidly connected to the output shaft.
In another embodiment the rotor is instead connected to the output shaft via a reduction gearing.
The reduction gearing may be a planet gear comprising a rim gear, asun gear and planet wheels there between, and wherein the rotor isconnected to the sun gear, the output shaft is connected to the planetwheels via a planet carrier, and wherein the rim gear is rotatively connected to the stator of the motor via a bridge.
An angle meter may be arranged to monitor the rotation of the stator.
The stator and the rotor may be disc-shaped and arranged opposite to each other.
Other features and advantages of the invention will be apparent from the figures and from the detailed description of the shown embodiment.
Short description of the drawings In the following detailed description reference is made to the accompanying drawings, of which: Fig. 1 shows a schematic view of a power tool according to a first specific embodiment of the invention; Fig. 2 shows a front view of a motor house according to the first embodiment of the invention; Fig. 3 shows a cut along the line III-III of the motor house shown infig. 2; Fig. 4 shows a perspective view of the motor house shown in fig. 2;Fig. 5 shows a perspective cut view of the motor house shown in fig.4; Fig. 6 shows a front view of a motor house according to a second embodiment of the invention; Fig. 7 shows a cut along the line VII-VII of the motor house shown in fig. 6; and Fig. 8 shows a perspective cut view of the motor shown in fig. 6.
Detailed description of the shown embodiment of the invention In fig. l a power wrench l0 according to a first embodiment of the invention is shown. The power tool comprises a housing ll that houses an electric motor l3. A lower part of the housing is formed as a handle 34 with a trigger 12 for driving the electric motor 13. Themotor 13 includes a stator 14 and a rotor 15. A power source 18, suchas rechargeable battery, is arranged below the handle 34 to power the motor 13. Typically, the power wrench further includes a control unit for controlling the motor, and a communication unit for communicating with a distant control station.
An output shaft 16 is arranged for delivering a torque to a joint thatis to be tightened or loosened. The output shaft is 16 drivinglyconnected to the rotor 15. In the shown embodiment the motor 13 isarranged inside a motor house 17, which is rigidly connected to themain housing 11. The motor may however just as well be directlysupported by the housing 11, such that the motor house could bedispensed with. In the shown embodiment the motor house 17 tightlyencloses and supports the rotor 15 and the stator 14 of the motor 13.As is indicated in fig. 1 the stator 14 is rotatively arranged with respect to the motor house 17.
The rotor 14 is rigidly connected to the output shaft 16, which in turn is connectable to a screw, bolt or nut for tightening or loosening a joint including said screw, bolt or nut. In the embodimentshown in figure 1 a socket 22 for connection to a bolt or a nut is arranged on the output shaft 16.
The stator 14 is resiliently arranged with respect to the housing 11and the motor house 17. A spring 19 is arranged to keep the stator 14in an initial position, which position is shown in the figures. In theshown embodiment the spring 19 is a torsional spring with a first end20 fixed to the stator 14 and a second end 21 arranged to the motor house 17.
The stator 14 will rotate within predetermined limits as a result ofreaction forces created during a tightening operation. The torquecreated by the motor will drive the output shaft and when the resistance in the joint increases will be transmitted as reaction forces to the stator. A normal tightening operation typically comprises a first threadening phase in which the bolt, screw or nut ofthe joint is rotated with only a substantially low torque applied bythe motor and a second phase in which a clamp force is build up in thejoint such that the torque increases continuously. In the first phasethe stator l4 will remain substantially still, but during the secondphase the stator l4 will rotate in the opposite direction with respectto the rotational direction of the rotor l5. The spring l9 may have aspring force that is proportional to its offset from the initialposition. There may be also be two or more springs. Further, thespring or springs may be progressive such that the torque acting onthe stator increases progressively with an increasing angular displacement of the stator.
In addition to the spring or springs end stops (not shown) may be arranged to limit the rotation of the stator. Typically, one singleend stop may be arranged to physically hinder the stator to rotatemore than 360° or l80° in either direction. Two end stops may howeverbe arranged to allow the stator l4 to rotate less than any specific angle in either direction, and to different degrees in the different directions.
Figure 3 and figure 5 shows a sectional view and a cut perspectiveview, respectively. As is visible in these figures the stator l4 isjournalled with respect to the motor house l7 by means of a front bearing 23 and a rear bearing 24. The rotor l5 is arranged opposite tothe stator l4. In the shown embodiment the rotor l5 and stator l4 aredisc-shaped. They may however also be cylindrical, one arranged coaxially inside the other.
An advantage with a disc-shaped stator and rotor is that it may implyan increased inertia in the stator, which increases the reaction torque that may be compensated by the rotation of the stator.
A second embodiment is shown in figures 6-8, in which the rotor is connected to the output shaft l6 via a reduction gearing. In the shown embodiment the reduction gearing is a planetary gear with a typical reduction ratio of about l:4. The rotor l5 is rigidly connected to asun wheel 28 of the planetary gear. A planet carrier 30 carries anumber of planet wheels 29 that rotate around separate planet gearshafts 32. In the shown embodiment three planet wheels 29 arearranged. There may however also be l, 2, 4 or more planet wheels. Theplanet carrier 30 is rigidly connected to the output shaft l6. A rimgear 3l is arranged to enclose the planet wheels 29 which will rotatearound the sun wheel 28 and their own shafts 32 as a function of therotation of the sun wheel 28, which in turn is implied by the rotation of the rotor l5.
The reaction forces that are created during a tightening operation areprovided to the rim gear 3l. In the prior art a rim gear is normallyrigidly arranged inside the housing so as to transmit the reactionforces to the housing of the power tool. In the inventive secondembodiment these reaction forces are instead transferred to the statorl4. Namely, the rim gear 3l is connected to the stator l4 via a bridge33. The bridge 33 is journalled with respect to the motor house l7 inthe front stator bearing 23, and the rotor is journalled with respect to the stator l4 in the front rotor bearing 25.
The inventive stator arrangement is intended to be controlled by meansof a control unit so as to deliver a controlled and well definedtorque to a joint. In addition to the torque transducer 27 arrangedinside the rotor shaft an angle encoder may be arranged to monitor therotation of the output shaft l6 and a meter may be arranged to monitorthe rotation of the stator l4. As the spring action of the spring l9is proportional to the angular displacement of the stator l4, and asthe reaction forces will be transmitted to the stator the angulardisplacement of the stator l4 will be an indirect indication of thereaction forces produced during a tightening operation. Hence, atorque meter, an angle meter or both may be used to monitor theangular displacement of the stator. A torque meter could be arrangedat the second end 2l of the spring l9 to register the force with which the spring acts on the motor house l7.
The control unit may further be configured to control the motor inresponse to the angular displacement of the stator l4. For instance,the control unit may be configured to limit the angular displacementof the stator l4 such that the experienced reaction torque will remainbelow a predetermined threshold. Further, a gyro (not shown) may bearranged to monitor the rotation of the housing around the rotationaxis of the output shaft. At a specific angular rotation of thehousing the motor may be slowed down or turned off as a safetyarrangement. Depending on the magnitude of the angular displacement ofthe housing the tightening operation may either be concluded a moment later or interrupted to be concluded at another time.
The control unit may be configured to control a tightening operation actively during a tightening operation, e.g. in order to reach a set target torque with as little reaction force as possible. The controlunit may also be configured to deliver torque pulses and to optimisethese pulses in response to the movement of the stator l4. Suchoptimisation may be dependent on many different parameters and may be readily tested by a person skilled in the art.
Above, the invention has been described with reference to two specificembodiments. The invention is however not limited to theseembodiments. It is obvious to a person skilled in the art that the invention maybe varied within its scope of protection, which is defined by the following claims.

Claims (9)

1. Claims1. A power wrench (10) including:- an electric motor (13) comprising a stator (14) and a rotor (15), - a torque delivering output shaft (16) that is drivingly connectedto the rotor (15), and- a housing (11,17) in which the stator (14) is arranged, characterised in that the stator (14) is resiliently arranged with(11,17), (14) respect to the housing wherein at least one spring (19) is arranged to urge the stator towards an initial position.
2. The power wrench (10) according to claim 1, wherein the at leastone spring acts in both directions and has a proportional spring forcethat is proportional to its angular displacement from the initial position.
3. The power wrench (10) according to claim 1, wherein the at leastone spring acts in both directions and has a spring force thatincreases in a non-linear manner with its angular displacement from the initial position.
4. The power wrench (10) according to anyone of the precedingclaims, wherein at least one end stop is arranged to limit therotation of the stator (14).
5. The power wrench (10) according to anyone of the precedingclaims, wherein the rotor (15) is rigidly connected to the outputshaft (16).
6. The power wrench (10) according to anyone of the claims 1-4,wherein the rotor (15) is connected to the output shaft (16) via areduction gearing.
7. The power wrench (10) according to claim 6, wherein the reductiongearing is a planet gear comprising a rim gear (31), a sun gear (18)and planet wheels (29) there between, and wherein the rotor (15) is connected to the sun gear (18), the output shaft is connected to the planet wheels (29) via a planet carrier (30), and wherein the rim gear(31) is rotatively connected to the stator (14) of the motor (13) viaa bridge (33).
8. The power wrench (10) according to anyone of the precedingc1aims, wherein an ang1e meter is arranged to monitor the rotation of the stator.
9. The power wrench (10) according to anyone of the precedingc1aims, wherein the stator (14) and the rotor (15) are disc-shaped and arranged opposite to each other.
SE1550487A 2015-04-24 2015-04-24 Low reaction power wrench SE1550487A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
SE1550487A SE1550487A1 (en) 2015-04-24 2015-04-24 Low reaction power wrench
PCT/EP2016/058319 WO2016169844A1 (en) 2015-04-24 2016-04-15 Low reaction power wrench

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE1550487A SE1550487A1 (en) 2015-04-24 2015-04-24 Low reaction power wrench

Publications (1)

Publication Number Publication Date
SE1550487A1 true SE1550487A1 (en) 2016-10-25

Family

ID=55754293

Family Applications (1)

Application Number Title Priority Date Filing Date
SE1550487A SE1550487A1 (en) 2015-04-24 2015-04-24 Low reaction power wrench

Country Status (2)

Country Link
SE (1) SE1550487A1 (en)
WO (1) WO2016169844A1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4029644B1 (en) 2021-01-19 2023-07-19 Volvo Truck Corporation A robot for tightening a series of bolt nuts on a vehicle chassis and manufacturing process

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5848655A (en) * 1997-05-29 1998-12-15 Ingersoll-Rand Company Oscillating mass-based tool with dual stiffness spring
DE102004022774B4 (en) * 2004-05-05 2015-09-17 Koenig & Bauer Aktiengesellschaft Arrangement of an electric motor for driving a cylinder of a rotary printing machine
DE102009020092A1 (en) * 2009-05-06 2010-11-11 Bayerische Motoren Werke Aktiengesellschaft Electrical machine i.e. electrical generator, for motor vehicle, has stator connected with rotor by bracket and movably supported in rotor, and magnetic field generation element arranged on outer slot
DE102011105345A1 (en) * 2011-06-21 2012-12-27 Fisw Steuerungstechnik Gmbh Electrical rotatory drive e.g. external rotor motor, for use in e.g. drilling machine, has housing supported relative to coaxial fixed drive part or to support body with rotatory rigidity and rotatory attenuation

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Publication number Publication date
WO2016169844A1 (en) 2016-10-27

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