Attachment part for a power tool and a tool assembly

An attachment part for a power tool includes an elongated housing including an upper housing part, a lower housing part and an interconnection structure that interconnects the upper and lower housing parts. An input gear for connection to an output shaft of a power tool is arranged at a first end of the housing. An output gear with an output interface is arranged at a second end of the housing. The interconnecting structure includes a sleeve member extending through a first central bore at the first end of the upper housing part, which sleeve member receives the input gear, and a fixation member extending through a second central bore at the first end of the lower housing part and which is arranged to be secured to the sleeve member to clamp the upper and lower housing parts. A tool assembly includes a power tool and the attachment part.

TECHNICAL FIELD

The present disclosure generally relates to power tools. In particular it relates to an attachment part for a power tool.

A power tool attachment part is generally used in confined spaces where it is not possible to use an ordinary power tool such as an ordinary nutrunner, due to that it is difficult to access the bolt or nut of the joint to be fastened or loosened. An attachment part is also known as a crowfoot, a front part attachment, an offset attachment or an offset gearhead. Below it will be referred to as an attachment part.

BACKGROUND

An attachment part includes a number of gears that transmit a rotating movement from an input gear with an input interface to an output gear with an output interface. At so called closed end attachment parts, the gears are generally located in a straight row, in meshing relationship, inside an elongate housing. At open end attachment parts, the output gear and output interface exhibit a slit for allowing the output interface to engage a pipe or the like in the radial direction in order to engage an nut or the like which enclose the pipe. For this reason, at open end attachment parts, the output gear meshes with two intermediate gears which, in turn mesh with the last one of a number of gears arranged in a straight row.

In both cases, the housing comprises a first end which houses the input gear, a second end which houses the output gear and an intermediate portion which connects the first and second ends. The input gear is often connected to or formed integral with an input interface which is arranged coaxial with the input gear for transmitting torque from the output shaft of the power tool. Typically, the output shaft of the power tool is formed of a square drive and the input interface exhibits a square recess with dimensions corresponding to the dimensions of the square drive. The square drive of many commonly used power tools and angle heads are standardized to specific dimensions, typically ¼, ⅜, ½ or 1 inch, depending of the torque to be transmitted. For receiving such standardized square drives, the diameter of the input interface sometimes needs to be larger than the gears arranged in the housing for transmitting the torque to the output interface.

This, in combination with that the input interface normally should be supported in bearings surrounding the input interface which also should form a connection to an adaptor for the attachment part, results in that the first end of the housing often has larger dimensions than the second end and the intermediate portion of the housing. Typically, the first end forms a generally cylindrical portion of the housing, the diameter of which is larger than the width of the elongate second end and intermediate portion.

Further, the dimensions of the attachment part are partly defined by the number and dimensions of the gears, the bearings supporting the gears and the dimensions of the input and the output interface. In addition, the wall thicknesses of the housing parts contribute to increase the overall dimensions of the attachment part.

Since the attachment parts are normally used at applications in confined spaces where it is difficult to reach and access the fasteners to be secured or loosened, it is highly desirable to keep the dimensions of the attachment part as small as possible. It is further advantageous if the attachment part may readily be disassembled and reassembled for allowing service, maintenance and replacement of components.

At previously known attachment parts, the upper and lower housing parts are normally secured together by means of a number of fixations screws which are distributed all around the periphery of the housing and each of which engages the upper and the lower housing part. WO 2014/095517 A1 discloses such an attachment part.

At the previously known attachment parts, the use of fixations screws distributed all around the housing requires that the wall thickness of the upper and lower housing parts is sufficiently great for accommodating the screws and for providing sufficient strength to the wall portions surrounding the screws. The so required wall thickness thus adversely adds to the total dimension of the attachment part. In addition, the comparatively high number of fixation screws required for a secure interconnection of the housing parts renders assembling and disassembling of the attachment part cumbersome and time consuming. This in turn increases the operations and time needed for service, maintenance and replacement of the interior components of the attachment part.

SUMMARY

An object of the invention is therefore to provide an enhanced attachment part for a power tool, which solves or at least alleviates the problems of the prior art.

Another object is to provide such an attachment part which allows for reduced outer dimensions while maintaining the torque capacity.

A further object is to provide such an attachment part which reduces the operations and time needed for service, maintenance and replacement of at least some of the interior components.

According to a first aspect of the present disclosure there is thus provided an attachment part for a power tool, which attachment part comprises; an elongate housing including an upper housing part, a lower housing part, and interconnection means for interconnecting said upper and lower housing parts. An input gear for connection to an output shaft of a power tool is arranged at a first end of the housing. An output gear with an output connection is arranged at a second end of the housing. The interconnecting means comprises a sleeve member extending through a first central bore in the first end of the upper housing part, which sleeve member receives the input gear; and a fixation member extending through a second central bore in the first end of the lower housing part and which is arranged to be secured to the sleeve member for clamping the upper and lower housing parts.

By arranging the sleeve member and the fixation member extending through a respective bore at the first end of the upper and lower housing parts such that they may be secured together for clamping the upper and lower housing parts, a sufficient interconnection between the upper and lower housing parts is achieved, at least at the first end of the housing. By this means there is no need for arranging any fixation screws at the periphery of the first end and extending through the wall portions of the upper and lower housing parts, at the first end of the housing. The wall thickness of the upper and lower housing parts may thereby be reduced at the first end, which in turn reduces the overall dimensions of the attachment part. By such reduced overall dimensions it is possible to use the attachment part for fastening bolts, screws or the like at even more confined spaces than what has been possible hitherto.

Additionally, the reduced number of fixation screws facilitates mounting and dismounting of the housing, thereby reducing the time and effort needed for service, maintenance and replacement of the interior components of the attachment part.

Further, the arrangement of the sleeve member and the fixation member extending through a respective central bore arranged at the first end of the upper and lower housing part greatly enhances access to the interior components arranged at the first end of the housing. By loosening the fixation member from the sleeve member, it is possible to withdraw these two members from their respective central bore. Thereby the interior of the of the first end of the housing becomes accessible from the outside such that e.g. the first gear, the bearings supporting the first gear and any additional interior components arranged at the first end of the housing may be dismounted and replaced through the central bores, without separating the upper and lower housing parts. This highly facilitates and speeds up service, maintenance and replacement of the interior components.

The sleeve member and/or the fixation part may comprise at least one radially protruding clamping flange.

The sleeve member and the fixation part may comprise cooperating threads for securing the fixation part to the sleeve member.

The sleeve member may exhibit at least one first bearing support surface.

The fixation member may exhibit at least one second bearing support surface.

The sleeve member may exhibit an opening arranged to allow the input gear to mesh with the output gear or with an auxiliary gear arranged between the input gear and the output gear.

A radially protruding clamping flange of the sleeve member may be arranged in clamping contact with a first outer contact surface of the upper housing part which first contact surface is arranged around the first central bore.

Alternatively, a radially protruding clamping flange of the sleeve member may be arranged in clamping contact with an intermediate component arranged between said clamping flange and an outer surface of the upper housing part.

The intermediate component may form part of an interface head for connecting the attachment part to a power tool or an angle head.

A radially protruding clamping flange of the fixation member may be arranged in clamping contact with a second outer contact surface of the lower housing part, which second contact surface is arranged around the second central bore.

The attachment part may further comprising an interface head for connection of the attachment part to a power tool.

The he interface head may be formed integral with the sleeve member. Alternatively the interface head and the sleeve member may be formed of separate components.

The input gear may be formed integral with an input interface for connection to an output shaft of a power tool.

According to a second aspect, there is provided a tool assembly comprising a power tool and an attachment part as described above.

The tool assembly may further comprise an angle head arranged operatively between the power tool and the attachment part.

The power tool may be a nutrunner.

DETAILED DESCRIPTION

FIG.1illustrates an attachment part100according to a first embodiment of the invention which is attached to an angle head10of a power tool (not shown) by means of an adaptor. In the shown example the adaptor20is an indexing adaptor which allows the attachment part100to be angularly adjusted in relation to the angle head20. In other words, the attachment part100may be rotated about a (as shown inFIG.1) vertical axis and fixed at different rotational positions relative to the angle head10such that the longitudinal direction of the attachment part is set at different angles relative to the longitudinal direction of the angle head. Such angular adjustment of the attachment part is normally referred to as indexing. By this means, access to nuts, bolts and the like which are to be fastened or loosened, in confined spaces, is facilitated.

With reference toFIGS.2a-f, the attachment part100is of the closed end type and comprises an elongate housing110and an interface head120. The interface head120protrudes above the housing110and is generally cylindrical. It comprises upper radially protruding flange portions122and lower radially protruding longitudinal splines124arranged to cooperate with corresponding means of the adaptor20shown inFIG.1for allowing the attachment part to be connected to and indexed relative to a power tool.

The elongate housing comprises an upper housing part111and a lower housing part112, which housing parts are interconnected along a longitudinal median plane. The housing110, just as the upper111and lower112housing parts exhibits a first end113and a second end114. The first113and second114ends are rounded and the first end113exhibits a radius of curvature which is larger than the radius of curvature if the second end114. The first113and second114ends are further connected by means of an intermediate portion115having a generally square cross section. The side walls of the intermediate portion115tapper slightly from the first end113towards the second end114. At some alternative embodiments however, the side walls of the intermediate portion may be mutually parallel or even diverging towards the second end. The upper housing part111further exhibits a first bore117which is centrally arranged at the first end113. The lower housing part112exhibits a second bore118(FIG.2d) which is centrally arranged at the first end113.

A flat and rectilinear gear train130is accommodated in the interior of the housing110. The gear train is arranged for transmitting rotational movement and torque from an output axis (not shown) of the angle head10to an output interface of the attachment part100. The gear train130comprises an input gear131arranged at the first end113of the housing110and an output gear132arranged at the second end114of the housing110. In the shown example, three intermediate gears133,134,135are arranged between the input gear131and the output gear132such that the input gear131meshes with intermediate gear133, which also meshes with intermediate gear134, which also meshes with intermediate gear135, which in turn also meshes with the output gear132. The intermediate gears133-135are supported by bearings arranged on respective shafts which are received in corresponding openings arranged in the upper111and lower112housing parts. The output gear132is supported by sliding bearings received by the housing parts111,112.

The input gear121is formed integral with an input interface136which exhibits a square recess which is arranged and dimensioned for receiving a square drive (not shown) at an output shaft (not shown) of the angle head10. Typically, the input interface136may be configured to receive a standardized square drive. In the shown example, it is configured to receive a ⅜ inch square drive. However, the input interface may also be configured for connection to other output shafts of an angle heads or power tools, which output shafts may have many other geometries. Additionally, the input gear and the input interface may in some embodiments be formed as separate interconnected components.

The output gear132is provided with an output interface132a. The output interface132ais tubular with an axial bore132band is arranged coaxially inside the output gear132. In this example the output interface132a, comprises a internal wall arranged in the bore132b(not visible) which wall exhibits a square through opening configured to receive a standardized tool or screw bit (not shown) with a square drive. However, the output interface could be configured in many other ways. E.g. it may be configured with a hexagonal geometry to directly engage a bolt, nut or the like which is to be fastened or loosened. The output interface may also be arranged as a square drive or the like which protrudes out from the housing110.

The attachment part100further comprises a sleeve member140, a fixation member150and an interface head120. These members140,150,120are arranged for interconnecting the upper111and lower112housing parts by clamping the housing parts at the first end113. The sleeve member140comprises a generally cylindrical sleeve141with four radially outwardly protruding clamping flanges142arranged at the upper edge of the sleeve141.

A through opening143extends from the lower edge of the sleeve upwardly.

The through opening143is arranged for allowing the input gear131to mesh with intermediate gear133. An internal thread144is arranged inside the sleeve141in proximity to the lower edge.

The fixation member150is generally rotational symmetrical and comprises an upper cylindrical shaft151, an intermediate cylindrical portion152and a lower clamping flange153which protrudes radially outwards from the lower edge of the cylindrical portion152. The cylindrical portion152is provided with an external thread154which corresponds to the internal thread144of the sleeve member140.

As best seen inFIG.2dthe sleeve member140and the fixation member150and the interface head120cooperate to clamp the upper111and lower112housing parts in the following manner. Further and as best seen inFIGS.2band2f, the sleeve member and the interface head are formed as two separate components at this embodiment. When assembling the attachment part100the output gear132and the intermediate gears133-135are positioned in the lower housing part112and the upper housing part111is aligned and brought into contact with the lower housing part112. Thereafter the two housing parts are interconnected by fixation screws (not shown). The fixation screws are inserted through fixation holes116arranged in the side walls of the lower housing part's112second end114and intermediate portion115and threadedly engaged in corresponding holes (not shown) arranged in the side walls of the second end and intermediate portion of the upper housing part111.

Thereafter, the sleeve member140, the interface head120and the fixation member150are mounted for accomplishing a strong and secure interconnection of the upper111and lower112housing parts' first ends113. The interface head120is first positioned on top of the upper housing part111, such that it surrounds the first bore117. Thereafter, the sleeve member is inserted from above through the interface head120and the first bore117until the clamping flanges142come into supporting contact with and inwardly protruding radial flange125of the interface head120. The sleeve member140should be rotationally oriented such that the through opening143faces the intermediate gears133-135and allows a portion of intermediate gear133to extend through the opening143for being able to mesh with the input gear131, when mounted.

Then a first bearing137is mounted inside the input gear131. The fixation member115is inserted from below through the second bore118and the exterior thread154is engaged with the interior thread144of the sleeve member by rotating the fixation member150. For this purpose the lower outer surface of the fixation member150may be provided with suitable tool receiving recesses (not shown). During rotation of the fixation member, the clamping flange153of the fixation member will contact the lower surface of the lower housing part112, around the second bore118. For a proper and secure positioning of the fixation member150, the lower housing part112exhibits a circular positioning recess119arranged at the edge of the second bore118and having a diameter which corresponds to the diameter of the fixation member's150clamping flange153. During such securing of the fixation member150to the sleeve member140, it is possible to select a suitable securing torque which results in a corresponding clamping force by which the upper111and lower112housing parts are pressed together. By this means the upper111and lower112housing parts are readily interconnected and securely held together at the first end113of the housing110.

When the housing parts111,112have been interconnected, a second bearing138for supporting the input interface136is inserted the into the interface head120. The first gear131with the input interface136is then inserted from above, through the interface head120and the sleeve member140, such that a lower bore139of the first gear131and the first bearing137receives the shaft151of the fixation member150. When so mounted the first gear131is supported by the first bearing which is supported by a circumferential exterior bearing support surface on the shaft151of the fixation member. The outer circumferential surface of the input interface136is supported by the second bearing138which in turn is supported by the interior bearing supporting surface of the interface head120.

Finally, the first gear131and the input interface136are axially locked in position by inserting a locking washer160into an interior circumferential groove of the interface head.

FIGS.3a-cillustrates an attachment part200according to a second embodiment of the invention. In the figures, the attachment part is illustrated when connected to an indexing adaptor270This attachment part200is of the open end type. Thus, the output interface232aand the output gear232exhibit a radial slit232C such that the output interface may be slid onto a pipe or the like in the radial direction and engaged with a nut, a bolt or the like which is thread onto and encloses the pipe. The open end attachment parts may thus be used for fastening and loosening e.g. nuts that surrounds a pipe such as an automotive brake fluid pipe.

The attachment part200comprises a housing210and an interface head220which protrudes upwards from the housing210. The housing210comprises an upper housing part211and a lower housing part210which are interconnected along a longitudinal plane of the housing210. The housing210, the upper211and the lower212housing parts exhibit a first end213and a second end214. At this embodiment the second end214is open in the longitudinal direction.

An input gear131is made integral with an input interface236and the input gear131is arranged inside the housing210at the first end213. The output gear232is arranged inside the housing210, at the second end214. The output interface232ais arranged concentrically inside the output gear232. Intermediate gears233,234a,234bare arranged inside an intermediate portion215of the housing210between the first213and second214ends.

The intermediate gears comprises one intermediate gear233which meshes with the input gear231and with two further intermediate gears234a,234b, arranged in parallel. The two further intermediate gears234a,234bmesh with the output gear232. Hereby it is possible to fully rotate the output gear232in spite of the radial slit232carranged in the output gear232. The attachment part200further comprises a reverse stop device260. The reverse stop device260cooperates, during reverse rotation, with the input gear231for stopping the rotation of the output gear as soon as the radial slit232cof the output interface232aand the output gear232is aligned with the open second end214of the housing. By this means it is assured that the output interface232amay readily be disengaged from the nut, bolt or the like when the fastening or loosening has been completed. Such reverse stop devices are well known to the skilled person and are not described more in detail here.

The second end214and the intermediate portion215of the upper211and lower212housing parts are interconnected by means of fixations screws216awhich extend trough holes216in the lower housing part and are treadedly engaged in corresponding holes (not shown) in the upper housing part211.

At the first end213the upper211and lower212housing parts are interconnected by means of a sleeve member240and a fixation member250which are secured together. At this embodiment the sleeve member240is formed integral with the interface head220, such that these members form a single component. The sleeve member240extends through a annular opening in the revers stop device260and a first central bore217arranged at the first end of the upper housing part211. A fixation member250extends through a second central bore218arranged at the first213end of the lower housing part212.

The sleeve member240exhibits a first radially protruding clamping flange242which bears against an upper surface of the reverse stop device260. A lower surface of the reverse stop device260in turn, bears against an upper surface of the upper housing part211, surrounding the first bore217. The fixation member250is secured to the sleeve member240by means of external threads254arranged at an intermediate portion251of the fixation member250and cooperating with corresponding internal threads244arranged at a bottom wall portion245of the sleeve member240. The fixation member250comprises a radially protruding clamping flange253which bears against a recessed lower surface of the lower housing part212. By rotationally tightening the fixation member250to the sleeve member240, the upper211and lower212housing parts are clamped by the sleeve member's first clamping flange242, via the reveres stop device260and the fixation member's250clamping flange253.

Additionally at this embodiment, the sleeve member240comprises a second radially outwardly protruding flange246which is arranged to bear against a lower radially inwardly protruding portion of a first adaptor ring271forming part of the adaptor270. The adaptor270further comprises a second adaptor ring.FIG.3billustrates two such alternative second adaptor rings272,273.

In addition and as indicated in the drawings, the component formed by the sleeve member240and the interface head220as well as the reverse stop device260are provided with form locking means which cooperates with corresponding means of the upper housing part211for preventing relative rotation between these components.

At this embodiment, the sleeve member240and the fixation member250are used not only for interconnecting the upper211and lower212housing parts at the first end213but also for fixation of the revers stop device260and the adaptor270to the attachment part200.

Further, at this embodiment the fixation member250comprises an upwardly extending shaft251, the circumferential surface of which forms a support surface for a first bearing237arranged inside the input gear231. The sleeve member240also exhibits, at its upper portion, an internal cylindrical surface245which forms a bearing support surface for a second bearing238supportingly arranged around the input interface236.

As in the first embodiment described above, the sleeve member240exhibits an opening243for allowing intermediate gear233to mesh with the input gear231.

InFIG.4an attachment part according to a third embodiment is shown. The attachment part300comprises a housing310including an upper housing part311and a lower housing part312. The housing310, the upper311and the lower312housing parts exhibit a first end313, a second end314and an intermediate portion315. A first central bore317is arranged at the first end of the upper housing part311and a second bore318s arranged at the first end313of the lower housing part312. A drive train (not shown) comprising two intermediate gears and an output gear are arranged inside the second end314and the intermediate portion315of the housing310. At the first end313, an input gear331integrally formed with externally protruding input interface336is arranged. At the first end313, the upper311and lower312housing parts are interconnected by means of a sleeve member340and a fixation member250which are secured together.

The sleeve member340comprises a lower cylindrical portion341ahaving a first diameter and an upper cylindrical portion341bhaving a second diameter which is larger than the first diameter. At the junction between the lower341aand the upper341bportions a clamping flange342is formed such that it protrudes radially outwards from the upper edge of the lower portion341a. At the lower end, the sleeve member340exhibits a bottom wall portion345which extends inwardly from the lower edge of the lower cylindrical portion341a. The bottom wall portion345is provided with a central circular through opening with an internal thread344.

The fixation member350comprises an upper vertically extending shaft351, a cylindrical intermediate portion352with an external thread354and a lower radially outwardly protruding clamping flange353.

For interconnecting the first end313of the upper311and lower312housing parts, the lower cylindrical portion341aof the sleeve member340is inserted from above through the first bore317until the clamping flange342of the sleeve member makes contact with an upper surface around the first bore317. The fixation member350is inserted from below through the second bore318. By rotating the fixation member350the external thread354of the intermediate portion352engages the internal thread344of the bottom wall portion345. Continued fastening rotation of the fixation member350will bring the clamping flange353of the fixation member350into contact with a recessed surface around the second bore318. By this means, the upper housing part311and the lower housing part312are clamped between the two clamping flanges342,353to thereby be strongly and securely interconnected. At this embodiment the shaft351of the fixation member350forms a bearing support surface for a first bearing337arranged inside the input gear331. The inner cylindrical surface of the sleeve member's340upper portion341bforms a support surface for a second bearing338arranged outside of the input interface336.

At a not shown embodiment the sleeve member and the fixation member are provided with securing means other than threads. Examples of such securing means are cooperating engagement members of the bayonet type, snap engagement members and other form-locking arrangements.

At another not shown embodiment the clamping flange of the sleeve member is arranged to be in clamping contact with an intermediate component other than an interface head or a reverse stop device, which is arranged between said clamping flange and the upper housing part. Examples of such intermediate components comprise adaptor rings forming part of an adaptor and rings, sleeves and other components forming part of other auxiliary devices.

As readily understood from the above description of different embodiments, the arrangement of a sleeve member and a fixation member which are secured together for clamping the upper and lower housing parts provide for a quick and easy way for accomplishing a strong and secure interconnection between the upper and lower housing parts. In addition the arrangement also provides for quick and easy dismounting for facilitating service, maintenance and replacement of the input gear, the input interface, the bearings supporting these components and any other components arranged at the inside of the first end of the housing. To this end it may be noted that these interior components may be directly accessed, removed and replaced through the first and/or second bore, simply by dismounting the fixation member and, at some instances, the sleeve member. The arrangement also eliminates the need of arranging a number of fixation screws or the like through the side wall of the housing parts, around the periphery of the first end. This in turn allows for that the material thickness of the housing parts may be reduced thereby to reduce the overall dimensions of the attachment part.