Power tool attachment part

Abstract

The present specification relates to a power tool attachment part (10) for use with a power tool, comprising an input gear wheel (22), an output gear wheel (23) and at least one intermediate gear wheel (24), and a hold and drive unit (30) comprising a nut socket (40) configured to rotate a nut, a screw holding member (50) and an attachment member (60), the screw holding member is axially movable but fixed in rotation with respect to the attachment member and comprises a base member (51) arranged to receive a screw engaging member (B) such that the screw engaging member is axially movable with respect to the base member, the hold and drive unit further comprises a first spring element (70) arranged to urge the base member (51) in a forward direction and a second spring element (80) arranged to urge the screw engaging member (B) in the forward direction.

Description

[0001] POWER TOOL ATTACHMENT PART

[0002] Technical field

[0003] The present invention generally relates to power tools attachment parts for a power tool for tightening of threaded fasteners, more particularly to such attachment parts comprising a hold and drive unit.

[0004] Background

[0005] Electrical power tools for tightening of threaded fasteners are known to be used in various industries. Such power tools may for example be electrically or pneumatically powered.

[0006] Power tool attachment parts are generally used in confined spaces where it is not possible to use an ordinary power tool to access a bolt or nut of the joint to be tightened. A power tool attachment part (also known as a crowfoot, a (geared) front part attachment or a (geared) offset attachment), i.e. an output gear extension that connect to the end of a tool, and typically includes a plurality of gear wheels that transmit a rotating movement from an input gear wheel to an output gear wheel. The gear wheels are generally located in a row, teeth against teeth, inside an elongated housing.

[0007] As the power tool attachment parts are generally used in confined spaces, the size of the power tool attachment part is an important feature.

[0008] Power tool attachment parts are further commonly used for example in the aerospace industry, where one special application is the use of power tool attachment parts utilizing so called hold and drive technology. A hold and drive unit is a unit which holds the screw while tightening the nut. Hold and drive technology / units are required in cases where it is neither possible nor convenient to hold the screw from the opposite side of a threaded end while tightening. Such units typically include some sort of screw holder arranged inside a socket (or similar) to hold the tip of a screw while tightening is being performed. The screw holder is always fixed, but it is able to move axially to make room for the screw, while the socket follows the nut running down. The socket (sometimes called drive socket or nut socket) is the part that turns and tightens the nut to the final torque and is connected to, and / or possibly integrally formed with, the output gear of the tool.

[0009] The constraints on the size due to the use in confined spaces mentioned above off course remains and poses an even greater challenge in the case of a power tool attachment part comprising such a hold and drive unit.

[0010] Hence, there is a need for an improved power tool attachment part, more particularly such an attachment part comprising a hold and drive unit, that can solve or at least mitigate the above-mentioned problems.

[0011] Summary

[0012] Accordingly, it would be desirable to provide a power tool attachment comprising a hold and drive unit which is offering improved accessibility. In particular, it would be desirable to provide such an attachment part having a particularly compact design. To better address one or more of these concerns, a power tool attachment, a power tool, a kit, and a hold and drive unit as defined in the independent claims is provided. Preferred embodiments are defined in the dependent claims.

[0013] According to a first aspect of the invention, a power tool attachment part for (use with) a power tool is provided, comprising an elongated housing, an input gear wheel for connection to an output shaft of the power tool, which input gear wheel is arranged at a first end of the housing, an output gear wheel with an output connection, which output gear wheel is arranged at a second end of the housing, and at least one intermediate gear wheel, which is arranged inside the housing to transmit rotation of the input gear wheel to the output gear wheel, wherein the power tool attachment part further comprises a hold and drive unit for tightening a screw and nut comprising a nut socket arranged to be driven by the output gear wheel and configured to rotate the nut relative to the screw, a screw holding member configured to at least indirectly hold, or engage, the screw to prevent the screw from rotating, and an attachment member adapted to be fixed to the housing, wherein the screw holding member is axially movable but fixed in rotation with respect to the attachment member, wherein the screw holding member comprises a base member arranged to receive a screw engaging member in a manner such that the screw engaging member is at least axially movable with respect to the base member, and wherein the hold and drive unit further comprises a first spring element arranged to bias, or urge, the base member in a forward direction defined from the screw holding member towards the screw; and a second spring element arranged to bias, or urge, the screw engaging member in the forward direction.

[0014] According to the first aspect, the power tool attachment part provides an inventive solution to the concerns described above by means of a design comprising a movable screw engaging member and springs arranged to bias, or urge, both the screw holding member and the screw engaging member in a forward direction.

[0015] More particularly, as mentioned above the screw holder needs to move axially to make room for the threaded part of the screw while the nut socket follows the nut running down. Due to the inventive design involving an axially moveable screw engaging member, the available distance is increased without increasing the outer height or the distance can alternative be kept the same while allowing for a decrease of the outer height of the power tool attachment part. The size, more particularly the height, of the power tool attachment part can thus be reduced, and the accessibility improved.

[0016] The housing of the power tool attachment part may include an upper housing part and a lower housing part and interconnection means for interconnecting said upper and lower housing parts such as screws. The power tool attachment part may further comprise a torque sensor configured to measure the applied torque. The power tool attachment part may further in some embodiments comprise a socket arranged concentrically with, and radially inside, the output gear wheel. Such a socket may further be integrally formed with the output gear wheel.

[0017] The screw holding member may be designed to extend at least partly beyond the elongated housing of the power tool attachment part, for example in an axial direction defined by the axis of rotation of the wheels. The nut socket may be adapted to be slidably received on the nut. The screw holding member may further be at least partly arranged inside, within and / or encircled by, the nut socket. The attachment member may comprise a cap portion, such as a cap portion adapted to fit the axially extending portion of the screw holding member, and a flange portion.

[0018] According to one embodiment, the first and second springs are helical springs, wherein the first and second spring are coaxially arranged. This may be advantageous in that a particularly compact design may be achieved and further in that the design can be easily adapted and designed to fit a certain application, with little or no addition to the size of the hold and drive unit.

[0019] In some embodiments, the second spring may be arranged to extend on an inner side of the helix formed by the first spring. In some embodiments, the base member may comprise a hollow cylindrical portion, wherein the first spring is arranged on an outer side of the cylindrical portion and the second spring is arranged on an inner side of the hollow cylindrical portion. Hereby, more spring travel may be realized in a more compact manner.

[0020] According to one embodiment, the first spring element is a conical spring. Hereby, an advantageously compact design may be achieved as the conical spring has a smaller height in its most compressed state.

[0021] According to one embodiment, the second spring element is arranged to act between the screw holding member and the screw engaging member to bias, or urge, the screw engaging member in the forward direction. In some embodiments, the second spring may be arranged to act between the base member and the screw engaging member. According to one embodiment, the screw holding member further comprises an end stop element, wherein the second spring element is arranged to act between the screw engaging member and the stop element to bias the screw engaging member in the forward direction. The end stop element may for example form an end stop at an upper end of the cylindrical portion of the screw holding member mentioned above.

[0022] According to one embodiment, the first spring element is arranged to act between the attachment member and the screw holding member to bias the screw holding member in the forward direction. For example, the screw holding member may comprise a flange portion against one end of the first spring may bear, such that the first spring acts between an inner side of the attachment member and the flange member.

[0023] According to one embodiment, the nut socket and the output gear are integrally formed.

[0024] According to one embodiment, the base member is a bit holder and the screw engaging member is a bit. According to one embodiment, the screw engaging member is a screw holder.

[0025] According to one embodiment, the screw holding member is arranged axially movable but fixed in rotation with respect to the attachment member by means of a two-flats coupling or a spline coupling. Other form-locking members are conceivable within the scope, such as a hexagon coupling or similar.

[0026] According to one embodiment, the attachment member is adapted to be fixed to the housing by means of screws.

[0027] According to one embodiment, the power tool attachment part is a crowfoot attachment.

[0028] According to a second aspect of the invention, a kit comprising a power tool and an attachment part according to any one of the embodiments described in the foregoing is provided. The power tool may be a handheld power tool or a fixtured tool. According to one embodiment, the referenced power tool is an electrically and / or battery powered tool. The tool may further be for example a pistol tool, an angle tool or a straight tool. According to a fourth aspect of the invention, a power tool comprising an attachment part according to any one of the embodiments described in the foregoing is provided. The power tool may be a handheld power tool or a fixtured tool.

[0029] According to a third aspect of the invention, a hold and drive unit for (use with) a power tool attachment part power tool attachment part according to any one of the embodiments described in the foregoing is provided.

[0030] Objectives, advantages and features conceivable within the scope of the second and third aspects of the invention are readily understood by the foregoing discussion referring to the first and second aspect of the invention.

[0031] Further objectives of, features of and advantages of the present invention will also become apparent when studying the following detailed disclosure, the drawings and the appended claims. Those skilled in the art realize that different features of the present invention can be combined to create embodiments other than those described in the following.

[0032] Brief description of the drawing

[0033] The invention will be described in the following illustrative and non-limiting detailed description of exemplary embodiments, with reference to the appended drawing, on which

[0034] Figure la is a perspective view of an exemplary power tool attachment part according to one embodiment.

[0035] Figure lb is a cross sectional view of an exemplary power tool attachment part according to one embodiment.

[0036] Figure 2a is a cross sectional view of an exemplary power tool attachment part according to one embodiment.

[0037] Figure 2b is an exploded view of an exemplary power tool attachment part according to one embodiment. All figures are schematic, not necessarily to scale and generally only show parts which are necessary in order to elucidate the invention, wherein other parts may be omitted or merely suggested.

[0038] Detailed description

[0039] In fig. 1 a power tool attachment part 10 for use with a power tool, such as a power tool for tightening of threaded fasteners, is shown in a perspective / cross sectional view.

[0040] The exemplified power tool attachment part 10 is a so called crowfoot or geared front attachment 10 and comprises an elongate housing 11. The elongated housing 11 comprises an upper housing part and a lower housing part. The upper housing part is interconnected with the lower housing part, for example by means of screws 12.

[0041] Fig. lb shows the power tool attachment part 10 in an exploded view. The power tool attachment part 10 comprises an input gear wheel or input gear 22 for connection to an output shaft of the power tool and an output gear 23 with an output connection arranged in the elongated housing 11. The input gear 22 is arranged ata first end Ila of the elongate housing 11. The output gear 23 is arranged ata second end 11b of the housing 11. An interface 1 for connection to the driving output of a power tool, such as a handheld power tool, may be provided at the first end Ila.

[0042] The input gear 22 is drivingly connected to the output gear 23 via a number of intermediate gears 24. In the shown example there are three intermediate gears comprising one first intermediate gear 24a, meshing with the output gear 23 and two second intermediate gears 24b arranged between the input gear 22 and the first intermediate gear 24a for transmitting rotation and torque therebetween. The number of intermediate gears may however be varied freely for suitable adaption of the length of the crowfoot, as long as there is one first intermediate gear 24a. The number of second intermediate gears 24b may thus be any integer from zero and up. The power tool attachment part 10 further comprises a hold and drive unit 30 for tightening a screw and nut. An exemplary hold and drive unit 30 is shown in cross section and in an exploded view in figures 2a and 2b respectively.

[0043] The hold and drive unit 30 may comprise a nut socket 40 arranged to be driven by the output gear wheel 23 and configured to rotate the nut relative to the screw, and a screw holding member 50 configured to at least indirectly hold, or engage, the screw to prevent the screw from rotating. The nut socket 40 may in some embodiments as shown in figures 2a and b be integrally formed with the output gear 23.

[0044] An attachment member 60 is, when in use, fixed to the housing 11 for example by means of screws, wherein the screw holding member 50 is arranged to be axially movable but fixed in rotation with respect to the attachment member 60. The screw holding member 50 may for example be arranged axially movable but fixed in rotation with respect to the attachment member 60 by means of a two-flats coupling. The attachment member 60 may also for example be referred to as a cap or cover.

[0045] The screw holding member 50 may comprise a base member 51 arranged to receive a screw engaging member B, such as a bit B or a screw holder, in a manner such that the screw engaging member B is at least axially movable with respect to the base member 51.

[0046] The hold and drive unit 30 further comprises a first spring element 70 arranged to bias, or urge, the base member 51 in a forward direction defined from the screw holding member towards the screw, indicated by arrow A, and a second spring element 80 arranged to bias, or urge, the screw engaging member B in the forward direction.

[0047] The first and second spring 70, 80 may for example be helical springs, and may further be coaxially arranged. The first spring 70 and / or the second spring 80 may further be conical spring(s). The first spring element 70 may further be arranged to act between the attachment member 60 and the screw holding member 50 to bias, or urge, the screw holding member in the forward direction, for example between the base member 51 and the screw engaging member. The base member 51 may for example comprise a flange portion 51a against one end of the first spring 70 may bear, such that the first spring 70 acts between an inner side of the attachment member 60 and the flange member 51a.

[0048] The second spring element 80 may further be arranged to act between the screw holding member 50 and the screw engaging member B to bias, or urge the screw engaging member in the forward direction. The screw holding member 50 may for example further comprise an end stop element 52, and the second spring element 80 may be arranged to act between the screw engaging member B and the stop element 52 to bias, or urge, the screw engaging member B in the forward direction.

[0049] Hereby, during tightening, as room must be made for the threaded part of the screw while the nut socket 40 follows the nut running down, the movable screw holding member 50 as well as the screw engaging member B may move axially and provide a longer travel distance without increasing the height of the power tool attachment part 1.

[0050] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiment. The skilled person understands that many modifications, variations and alterations are conceivable within the scope as defined in the appended claims. Additionally, variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising” does not exclude other elements or steps and the indefinite article "a” or "an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope of the claims.

Claims

CLAIMS1. A power tool attachment part (10) for use with a power tool, comprising: an elongated housing (11), an input gear wheel (22) for connection to an output shaft of the power tool, which input gear wheel is arranged at a first end of the housing, an output gear wheel (23) with an output connection, which output gear wheel is arranged at a second end of the housing, and at least one intermediate gear wheel (24), which is arranged inside the housing (11) to transmit rotation of the input gear wheel (22) to the output gear wheel (23) , wherein the power tool attachment part further comprises a hold and drive unit (30) for tightening a screw and nut comprising: a nut socket (40) arranged to be driven by the output gear wheel and configured to rotate the nut relative to the screw; a screw holding member (50) configured to at least indirectly hold the screw to prevent the screw from rotating, and an attachment member (60), adapted to be fixed to said housing, wherein said screw holding member is axially movable but fixed in rotation with respect to said attachment member, wherein said screw holding member comprises a base member (51) arranged to receive a screw engaging member (B) in a manner such that said screw engaging member is at least axially movable with respect to said base member, and wherein said hold and drive unit further comprises: a first spring element (70) arranged to urge said base member (51) in a forward direction defined from the screw holding member towards the screw; anda second spring element (80) arranged to urge said screw engaging member (B) in said forward direction.

2. Power tool attachment part according to claim 1, wherein said first and second spring are helical springs, and wherein said first and second spring are coaxially arranged.

3. Power tool attachment part according to claim 1 or 2, wherein said first spring element is a conical spring.

4. Power tool attachment part according to any one of the preceding claims, wherein said second spring element (80) is arranged to act between the screw holding member (50) and the screw engaging member (B) to urge the screw engaging member in said forward direction.

5. Power tool attachment part according to any one of the preceding claims, wherein said first spring element (70) is arranged to act between said attachment member (60) and the screw holding member (50) to urge said screw holding member in said forward direction.

6. Power tool attachment part according to any one of the preceding claims, wherein said nut socket and said output gear are integrally formed.

7. Power tool attachment part according to any one of the preceding claims, wherein said base member is a bit holder and said screw engaging member is a bit.

8. Power tool attachment part according to any one of the preceding claims 1-6, wherein said screw engaging member is a screw holder.

9. Power tool attachment part according to any one of the preceding claims, wherein said screw holding member further comprises an end stop element (52), and wherein said second spring element is arranged to act between said screw engaging member and the stop element to urge said screw engaging member in said forward direction.

10. Power tool attachment part according to any one of the preceding claims, wherein said screw holding member is arranged axially movable but fixed in rotation with respect to said attachment member by means of a two-flats coupling or a spline coupling.

11. Power tool attachment part according to any one of the preceding claims, wherein said attachment member is adapted to be fixed to said housing by means of screws.

12. Power tool attachment part as claimed in any one of the preceding claims, wherein the power tool attachment part is a crowfoot attachment.

13. Power tool comprising an attachment part according to any of claims 1-1214. Kit comprising a power tool and an attachment part according to any of claims 1-12.

15. Hold and drive unit for use with a power tool attachment part according to any one of claims 1-12, for tightening a screw and nut comprising: a nut socket arranged to be driven by the output gear wheel and configured to rotate the nut relative to the screw; a screw holding member configured to at least indirectly hold the screw to prevent the screw from rotating, andan attachment member, adapted to be fixed to said housing, wherein said screw holding member is axially movable but fixed in rotation with respect to said attachment member, wherein said screw holding member comprises a base member arranged to receive a screw engaging member in a manner such that said screw engaging member is at least axially movable with respect to said base member, and wherein said hold and drive unit further comprises: a first spring element arranged to urge said base member (51) in a forward direction defined from the screw holding member towards the screw; and a second spring element arranged to urge said screw engaging member (B) in said forward direction.

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