Handheld power tool

Abstract

The present specification relates to a handheld power tool for tightening of threaded fasteners, the power tool comprising an output shaft (5) drivingly connected to a motor and having an interface arranged to receive a socket (S), wherein the output shaft further comprises a safety arrangement for preventing loss of the socket in case of damage to the interface, the safety arrangement comprising an elongated member (10), and a retaining member (3) secured to a rear portion of the output shaft, wherein a first end of the elongated member is arranged to restrict axial movement of a front portion (5a) of the output shaft and wherein the retaining member is arranged to restrict axial movement of the elongated member.

Description

Technical field

[0001] The present specification generally relates to handheld power tools, more particularly to socket receiving interfaces for such power tools.Technical Background

[0002] Handheld power tools for tightening are known to be used in various industries, where the size of the threaded fasteners, such as screws or nuts, used varies from very large to very small.

[0003] When very large fasteners are used, they often need to be tightened to very high torque levels. This places significant strain on the tools, demanding high strength from both the tools and their accessories. High stress and loads can lead to failures in various parts of the tools, reducing productivity and posing serious workplace safety hazards. Additionally, tightening large screws to the required high torque levels necessitates large and heavy sockets. The failure or loss of such a socket can have particularly serious consequences.

[0004] Moreover, high torque tools are frequently used in construction applications, such as in the energy sector for wind turbine tower maintenance. These tasks often occur at high altitudes, increasing the risks significantly if a tool or socket breaks.

[0005] Hence there exists a need for improvement in the field of such handheld power tools.Summary of the invention

[0006] Accordingly, it would be desirable to provide a design which improves workplace safety. In particular, it would be desirable to provide such a design which does not add unnecessary complexity and bulkiness to the tool. To better address one or more of these concerns a handheld power tool as defined in the independent claim is provided. Preferred embodiments are defined in the dependent claims.

[0007] According to a first aspect of the invention, a handheld power tool for tightening of threaded fasteners, is provided, the power tool comprising an output shaft drivingly connected to a motor and having an interface arranged to receive a socket, wherein the output shaft further comprises a safety arrangement for preventing loss of the socket in case of damage to the interface, the safety arrangement comprising an elongated member, and a retaining member secured to a rear portion of the output shaft, wherein a first end of the elongated member is arranged to restrict movement of a front portion of the output shaft, and wherein the retaining member is arranged to restrict axial movement of the elongated member (in at least one direction).

[0008] According to the first aspect, the handheld power tool provides an inventive solution to the concerns described above by means of a design incorporating a safety arrangement for preventing loss of the socket in case of damage to the socket receiving interface by allowing for restricting movement of the front portion of the output shaft when needed, for example for preventing a socket attached to the output shaft from falling. More particularly, an additional connection between the front and rear portion of the output shaft is formed by means of the elongated member and the retaining member, such that a socket secured to the front portion cannot detach from the rear portion (and hence the tool) and fall even if the output shaft breaks therebetween. As the safety arrangement is comprised by the outputs shaft, a particularly compact solution may be achieved.

[0009] The power tool according to the invention therefore cleverly provides improved workplace safety by means of the provision of the cooperating elongated member and retaining member secure to, for example by being provided in or comprised by, the output shaft, in a manner reducing complexity and bulkiness of the tool.

[0010] The retaining member may for example be fixed to the output shaft, the elongated member may be fixed to the front end of the output shaft. In some embodiments, the safety arrangement may be provided in the output shaft.

[0011] The referenced handheld power tool may for example be a pistol nut runner, for example an electric pistol nut runner. The handheld tool may in some embodiments be a transducerized tool. Further, the tool may depending on the application further comprise a suitable reaction arm for example a swiveling reaction bar.

[0012] In some embodiments, the handheld power tool is configured to deliver a torque in the range 200-20000NM, such as 200-5000 Nm. The advantages of the interface safety arrangement design are of particular importance as the torque delivered, and hence the size of the socket and the potential risks involved, increases.

[0013] According to one embodiment, the tool is a battery powered tool, i.e. a tool further comprising a battery.

[0014] In one embodiment, the first end of the elongated member is secured to a front portion of the output shaft. According to one embodiment the axial movement of the elongated member may be restricted by the retaining member if the front portion of the output shaft detaches.

[0015] Hereby, the movement is restricted if the front portion (e.g. a portion engaging the socket) becomes detached from the rear, i.e. the remaining portion (e.g. a tool side portion) of the output shaft. Or in outer words if the output shaft has been damaged, e.g. cracked, such that the outer portion is broken off.

[0016] The arrangement may for example be such that the movement of the elongated member is affected or restricted by the retaining member in a manner such that during normal operation, the retaining member does not affect the engagement between and / or the operation of the tool and / or socket.

[0017] According to one embodiment the elongated member is allowed to move axially over a predetermined distance upon detachment, before being (fully) retained by the retaining element.

[0018] By being fully retained may be understood that the movement of the elongated element is halted, i.e. brough to a stop, such that the elongated member can not move any further with respect to the retaining element and / or the remaining portion of the output shaft. The distance may for example be a short distance, such as a distance shorter than 10 mm, such as a distance shorter than 5 mm.

[0019] Hereby, the elongated element may be kept in an unloaded state, i.e. not bearing any force or load, as the front portion of the output shaft detaches, i.e. at the time of breakage. At the moment of detachment, i.e. as the output shaft breaks, a high load peak occurs. By allowing for the elongated member to stay unloaded at this stage, damage to the elongated member and / or outer parts of the output shaft may be avoided.

[0020] In some embodiments, to achieve a similar effect, the elongated member is fixed to the retaining element (for example at the second end) and the first end of the elongated member (element) restricts or limits movement of the front portion of the output shaft if the front portion of the output shaft detaches. The front portion of the output shaft may for example be allowed to move axially over a predetermined distance upon detachment, before being engaged by and / or (fully) retained by the elongated member. The distance may for example be a short distance, such as a distance shorter than 10 mm, such as a distance shorter than 5 mm.

[0021] The stop member may for example be a washer or similar, fixed to the (tool side portion of) the output shaft. The washer may for example have a central opening through which the elongated member may be arranged to extend.

[0022] The elongated member may for example, according to one embodiment, be allowed to move axially (freely) over a (short) gap, such as an air gap, upon detachment, before being (fully) retained by the retaining element. The elongated member may for example move freely over the predetermined distance before engaging, e.g. coming into contact with, the retaining member.

[0023] According to one embodiment, the retaining element is compliant, wherein the elongated member is allowed to move axially against the resistance of the compliant retaining member over a predetermined distance upon detachment, before being (fully) retained by the retaining element. By compliant may be understood a less stiff retaining element allowing some amount of deformation, the compliant element may for example be a compliant, or "soft", washer such as thin washer. In such an embodiment, the movement of the compliant restraining element may be limited, i.e. be stopped, after the predetermined distance such that the elongated member is fully retained. The elongated member may in such an embodiment be arranged to be (more or less) in contact with the retaining member. The elongated member may further be fixed to the retaining element, for example at the second end.

[0024] In some embodiments, the output shaft / interface may comprise a stop (such as a shoulder or similar) arranged to limit the axial movement of the retaining member.

[0025] According to one embodiment, the elongated member is arranged to move independently with respect to the retaining member as long as the output shaft is intact. The elongated member may for example be arranged, such that rotational and / or axial movement is not affected by the retaining member as long as the output shaft is intact. In some embodiments, the front portion of the output shaft is arranged to move independently with respect to the elongated member as long as the output shaft is intact.

[0026] In some embodiments the elongate member may be a pin. In other embodiments, the elongated member may be a wire.

[0027] According to one embodiment, the retaining member comprises an opening through which the elongated member may extend.

[0028] According to one embodiment, the elongated member comprises an enlarged portion arranged at an opposite side of the retaining member from the first end, the enlarged portion being larger than the opening provided in the retaining member. For example such that the enlarged portion may not pass the opening, thus (potentially) limiting or restricting the axial movement of the elongated member in a forward direction. The enlarged portion may for example be a radially protruding portion such as a shoulder.

[0029] According to one embodiment, the elongated member comprises a head portion arranged at a second end, the dimension of the head being larger than the opening provided in the retaining member.

[0030] According to one embodiment, the elongated member is a screw, the enlarged portion may be formed by the screw head.

[0031] According to one embodiment, the elongated member is secured to the front end of the output shaft by means of threads. In some embodiments, the front end of the output shaft may comprise an intermediate member secured to the output shaft, to which the elongated member may be secured for example by means of threads.

[0032] According to one embodiment, the elongated member extends through an axially extending bore formed in the output shaft.

[0033] According to one embodiment, the output shaft further comprises an inner cavity, and the retaining member is arranged in the inner cavity. The retaining member may for example be a washer, fixed to the walls of a substantially cylindrical inner cavity.

[0034] The interface may be suitably adapted such that the socket may be secured, or fixed, to the front portion of the output shaft. According to one embodiment, the interface may for example further comprise a hole for receiving retaining pins arranged to secure a socket to the output shaft.

[0035] According to one embodiment, the power tool further comprises a housing in which a motor coupled to an outgoing axle defining an axial direction is arranged and a front gear unit attached to the housing at a front end thereof, wherein the output shaft is provided at a front end of the front gear unit. According to one embodiment, the output shaft may for example be integrally formed with a planet holder or carrier of the front gear unit.

[0036] 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.Brief description of the drawing

[0037] 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 Figure 1 is a perspective view of a handheld power tool according to one embodiment. Figure 2 is a perspective cross sectional view of a front end of a power tool according to one embodiment. Figure 3 is a perspective cross sectional view of a front end of a power tool according to one embodiment.

[0038] 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.Detailed description

[0039] An exemplary hand-held power tool 1 is shown in perspective view in figure 1, the illustrated tool 1 being a battery powered pistol type nut runner comprising a housing H in which a motor (not shown) drivingly connected to (for example via a transmission) an output shaft 5 is arranged. A front gear unit 20 may be attached at the front end of the tool 1.

[0040] An example of a front end of a handheld power tool 1 is shown in cross sectional view in fig. 2. The power tool comprises an output shaft 5 having an interface 100 arranged to receive a socket (not shown). The output shaft 5 may for example be integrally formed with a planet holder 21 or carrier 21 of the front gear unit 20.

[0041] The output shaft 5 further comprises a safety arrangement for preventing loss of the socket in case of damage to the interface 100, the safety arrangement comprises an elongated member 10, and a retaining member 3 secured to a rear portion (or tool side portion) 5b of the output shaft 5.

[0042] The retaining member 3 may be arranged to restrict at least axial movement of the elongated member 10 in at least one direction. For example, the axial movement of the elongated member 10 may be restricted by the retaining member 3 if the front portion 5a of the output shaft 5 detaches, i.e. becomes separated from the rear or tool side portion 5b of the output shaft 5 for example by a crack forming between the first and second portions 5a, 5b causing the front portion 5a to break off. The axial and / or rotational movement of the elongated member 10 may be un-affected by the retaining member 3 as long as the output shaft 5 is intact, i.e. during normal operation.

[0043] A first end 10a of the elongated member 10 may be secured to a front portion (or fastener side portion) 5a of the output shaft 5, for example by means of threads provided directly in the output shaft 5 or in an intermediate member 51 fixed to the front end 5a of the output shaft 5.

[0044] The retaining member 3 may comprise an opening 31 through which the elongated member 10 may extend. One example of a retaining member 3 is a washer 3 having a central opening 31. The retaining member 3 may be suitably secured to a rear portion (or tool side portion) 5b of the output shaft 5. The output shaft 5 may for example comprise an inner cavity 52, and the retaining member 3 may be arranged in the inner cavity 52.

[0045] The elongated member 10 may extend through the cavity 52. The elongated member 10 may (further) extend through an axially extending bore 54 formed in the output shaft 5.

[0046] The elongated member 10 may further comprise a larger portion 11, such as a head portion 11 arranged at an opposite side of the retaining member 3 from the first end 10a, e.g. at a second end 10b, the dimension of the head 11 being larger than the opening 31 provided in the retaining member 3 such that the enlarged portion 11 may not pass the opening 31. One example of an elongated member 10 having a head portion 11 is a screw. Hereby, as the head portion 11 engages (i.e. is stopped by) the smaller opening 31, axial movement of the elongated member 10 will be prevented in a forward axial direction in the event that the front portion 5a of the output shaft 5 detaches. Forward being a direction defined from the tool towards the socket.

[0047] The elongated member 10 may for example be allowed to move axially over a short predetermined distance d upon detachment, before being fully retained by the retaining element. The distance d may be for example approximately 5 mm. The elongated member 10 may for example be allowed to move over a short air gap G.

[0048] Hereby, the elongated member 10 is not bearing load as the front portion 5a of the output shaft 5 detaches, i.e. at the time of breakage, thus avoiding damage to the elongated member 10 and / or outer parts of the output shaft 5 due to peak loads.

[0049] To secure the socket to the output shaft 5, the interface 100 may further comprise one or more holes 101 for receiving retaining pins (not shown). The holes 101 may be arranged such that the socket S is secured to the front portion 5a of the output shaft 5, such that the socket may be retained by the elongated member 10 secured to the front end 5a, in case of failure of the interface 100.

[0050] Another example of a front end of a handheld power tool 1 comprising an output shaft 5 is shown in cross sectional view in fig. 3. The output shaft 5 comprising a similar example of a safety arrangement for preventing loss of the socket S in case of failure comprising an elongated member 10, and a retaining member 3 secured to a rear portion (or tool side portion) 5b of the output shaft 5.

[0051] The retaining member 3 is arranged to restrict axial movement of the elongated member 10, and similarly to the example shown in fig. 2, the elongated member 10 comprises a head portion 11. The head portion 11 is however arranged at the front end 5a of the shaft 5. More particularly, the head portion 11 is arranged to be engaged by a structure 40 should the output shaft 5 break. Hence, the axial movement of the elongated member 10 and thus of the front portion 5a may be restricted by the retaining member 3 if the front portion 5a of the output shaft 5 detaches. During normal operation, i.e. as long as the output shaft 5 is intact, the front portion 5a of the output shaft 5 remains un-affected by the elongated element 10 and / or the retaining member 3.

[0052] The elongated member 10 is in this example fixed to the retaining member 3, for example via intermediate member 51 (for example by means of threads). The intermediate member 51 may e.g. be arranged in an opening 31 provided in the retaining element.

[0053] The retaining element 3 shown in fig. 3 may further be described as being compliant, i.e. allowing some amount of deformation, examples include a compliant or soft, washer 3. Hereby, the elongated member 10 is allowed to move axially against the resistance of the compliant retaining member 3 over a predetermined distance upon detachment, before being fully retained by the retaining element 3. The output shaft 5 and / or the interface may for example comprise a stop or shoulder 55 arranged to limit the axial movement of the retaining member 3 and thus allowing for the elongated member 10 to be fully retained.

[0054] Hereby axial movement of the elongated member 10 will be restricted by member 3 in a forward axial direction in the event that the front portion 5a of the output shaft 5 detaches.

[0055] 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, form 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

1. A handheld power tool (1) for tightening of threaded fasteners, the power tool comprising an output shaft (5) drivingly connected to a motor and having an interface (100) arranged to receive a socket (S), wherein the output shaft further comprises a safety arrangement for preventing loss of the socket in case of damage to the interface, the safety arrangement comprising an elongated member (10), and a retaining member (3) secured to a rear portion (5b) of the output shaft (5), wherein a first end (10a) of the elongated member is arranged to restrict movement of a front portion (5a) of the output shaft, and wherein the retaining member (3) is arranged to restrict axial movement of the elongated member (10).

2. Handheld power tool according to claim 1, wherein the axial movement of the elongated member (10) may be restricted by the retaining member if the front portion (5a) of the output shaft (5) detaches.

3. Handheld power tool according to claim 2, wherein the elongated member (10) is allowed to move axially over a predetermined distance (d) upon detachment, before being fully retained by the retaining element (3).

4. Handheld power tool according to claim 2 or 3, wherein the elongated member (10) is allowed to move axially over a gap (G) upon detachment, before being fully retained by the retaining element (3).

5. Handheld power tool according to any one of claims 2-4, wherein the retaining element (3) is compliant and wherein the elongated member (10) is allowed to move axially against the resistance of the compliant retaining member (3) over a predetermined distance (d) upon detachment, before being fully retained by the retaining element (3).

6. Handheld power tool according to any one of the preceding claims, wherein the elongated member (10) is arranged to move independently with respect to the retaining member (3) as long as the output shaft (5) is intact.

7. Handheld power tool according to any one of the preceding claims, wherein the retaining member comprises an opening (31) through which the elongated member (10) extends,8. Handheld power tool according to any one of the preceding claims, wherein the elongated member comprises an enlarged portion (11) arranged at an opposite side of the retaining member (3) from the first end (10a), the enlarged portion being larger than the opening provided in the retaining member.

9. Handheld power tool according to claim 8, wherein the elongated member is a screw.

10. Handheld power tool according to any one of the preceding claims, wherein the elongated member (10) is secured to the front end of the output shaft by means of threads.

11. Handheld power tool according to any one of the preceding claims, wherein the elongated member extends through an axially extending bore (54) formed in the output shaft (5).

12. Handheld power tool according to any one of the preceding claims, wherein the output shaft (5) further comprises an inner cavity (52), and wherein the retaining member (3) is a washer arranged in the inner cavity.

13. Handheld power tool according to any one of the preceding claims, wherein the interface (100) further comprises a hole (101) for receiving retaining pins arranged to secure a socket (S) to the output shaft (5).

14. Handheld power tool according to any one of the preceding claims, further comprising a housing in which a motor coupled to an outgoing axle; and a front gear unit (20) attached to the housing at a front end thereof, wherein the output shaft (5) is provided at a front end of the front gear unit.

15. Handheld power tool according to claim 14, wherein the output shaft is integrally formed with a planet holder (21) of the front gear unit.

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