CN214394042U - Expansion unit for power tool and handheld electric tool - Google Patents

Abstract

The present invention relates to an extension unit for a power tool and a hand-held power tool, the extension unit for a power tool comprising a first body part (10) and a second body part (20), the first body part comprising one of a rear end part (10a) connected to an output shaft of the power tool and a front end part (20b) adapted to engage with a threaded joint, and the second body part comprising the other. The second body portion is at least partially disposed in the first body portion and allows relative rotation between the first and second body portions such that one of the first and second body portions can rotate within a predetermined allowable angle range while the other engages the nipple. The present description also relates to a corresponding method, a power tool and a computer-readable storage medium.

Description

Expansion unit for power tool and handheld electric tool

Technical Field

The present invention relates generally to impulse tightening, and more particularly to impulse tightening using a direct drive power tool.

Background

Pulsed tightening, which transmits torque to the joint in repetitive pulses, is known, for example, to reduce the amount of reactive torque felt by the operator. For example, so-called impulse tools are known which comprise an impulse unit arranged to intermittently transfer energy to an output shaft for transferring torque impulses. In other cases, it is also possible to use a direct-drive power tool for pulse-type tightening, in which an electric motor accommodated in an electric pulse tool applies a torque to an output shaft in a pulse manner.

In this case, the pulses are provided by accelerating the electric motor within the inherent play, which is present for example in the gearbox between the electric motor and the output shaft and may also include any play between the output shaft and a receiving structure, for example a socket, or an extension provided on the output shaft. Rotational energy is thus built up in the tool, which can be transmitted to the screw in the form of torque pulses when the play is closed. However, the amount of kinetic energy available using this strategy is limited, as there may be only a very limited amount of play available in the tool before the function is compromised.

In order to alleviate some of these problems, attempts have been made to provide such tools with a dedicated so-called play unit, which allows the motor to accelerate in a greater play. Thus, the amount of rotational energy built up in the tool and thus transmitted to the screw in the form of torque pulses may be increased to a certain extent.

However, there still exists a problem in that, for example, existing tools need to be modified and redesigned to accommodate such a unit, which may instead result in the need for multiple tools. Let alone such units of course also increase the complexity and size of the tool.

Accordingly, there is a need for improvements in the field of impulse tightening, particularly those using direct drive tools.

SUMMERY OF THE UTILITY MODEL

It is therefore desirable to provide pulsed tightening using a direct drive tool in which a greater amount of energy/torque can be transferred in a manner that repeats the torque pulses. In particular, it is desirable to provide a solution that does not significantly increase the size and complexity of the tool. To better address one or more of these concerns, an expansion unit, a method in a handheld power tool, and a handheld power tool are provided. Preferred embodiments are defined as follows.

According to a first aspect of the present invention, an extension unit for a power tool adapted to perform a tightening operation is provided. The expansion unit comprises a first body part comprising one of a rear end portion connected to the output shaft of the power tool and a front end portion adapted to engage with a nipple, i.e. a nipple adapted to engage with a threaded joint, and a second body part comprising the other of the rear end portion connected to the output shaft of the power tool and the front end portion adapted to engage with a nipple. Wherein the second body portion is at least partially disposed in the first body portion, and wherein relative rotation between the first and second body portions is permitted such that when one of the first and second body portions is engaged with the engagement sleeve (e.g., when the engagement sleeve is in tight or near tight engagement with a threaded fitting), the other of the first and second body portions is able to rotate within a predetermined permitted range of angles.

According to a first aspect, the expansion unit (or expansion piece, expander or adapter-these terms will be used interchangeably in this specification) provides an inventive solution to the above concerns by a two-piece design that provides a relatively large and well-defined angular play within the expansion unit. This is achieved by allowing relative rotation between two body portions, each body portion being engaged with a respective one of a socket (or the like) which in turn is engaged with a coupling and an output shaft of the tool. Thus, greater play is provided in a convenient and flexible manner, without requiring modification to the power tool itself, as compared to play present in previous designs, such as the gear boxes described above. This is because, as is known in the art, the extension piece is a device or unit adapted to be arranged between the power tool and the socket, so that a user can, for example, access screws that are difficult to access using a standard socket. Moreover, because the extension sets up between instrument output and nipple, the utility model discloses an extension can be used with standard nipple to the flexibility that provides has been increased. In addition, due to the play in the extension unit, the vibration level and the reaction torque affecting the operator are significantly reduced, thus also improving the ergonomics of the workplace. The skilled person realizes that the predetermined angular intervals may also represent predetermined time intervals.

Thus, the extension piece according to the above skillfully increases the energy transferred in each torque pulse, while improving the ergonomics of the operator.

Those skilled in the art will appreciate that similar designs may be used for so-called adapters (e.g., quick-change adapters) to provide similar functionality.

Relative rotation is therefore particularly important and useful when the nipple with which the extension is engaged is in turn engaged with a threaded joint, and more particularly when the threaded joint is in tight or near tight engagement and rotation of the nipple and of the body portion of the extension with which the nipple is engaged is resisted.

The second body portion is at least partially arranged in the first body portion, i.e. the second portion is at least partially arranged inside the first body portion, enclosed, surrounded or covered by the first body portion.

The rear end portion of the output shaft connected to the tool and the front end portion adapted to engage with the nipple may comprise engagement means of any suitable design, such as hexagonal, square or the like. For example, the rear end portion of the extender may have a square cross-section recess for receiving a square end of the power tool output shaft, and the front end of the extender may have a square output adapted to engage the nipple. Embodiments are contemplated that include any combination of square female/male inputs and outputs and hexagonal female/male inputs and outputs, and those skilled in the art will appreciate that any other shape than hexagonal may be used, such as a quincunx shape.

Suitable materials include steel, preferably hardened steel.

According to one embodiment, the first body portion is an at least partially tubular body portion and comprises an open cavity provided at a first end of the body portion, and wherein the second body portion is at least partially provided in the open cavity. For example, in one embodiment, the open cavity may have a cylindrical shape.

According to one embodiment, the first body portion comprises a first end face and the second body portion comprises a second end face, and wherein the first and second end faces lie in a same plane. Thus, in such embodiments, the second body portion may be disposed entirely within the space defined by the cavity, i.e., entirely surrounded by the first body portion.

According to one embodiment, the first body part comprises engagement means adapted to engage corresponding engagement means comprised by the second body part, thereby providing a mechanical stop limiting the relative rotation. Examples include a protrusion that engages with a corresponding groove and a protrusion that engages with a corresponding protrusion.

According to one embodiment, the first body portion comprises a first radial projection projecting radially inwardly to form a first shoulder, and wherein the second body portion comprises a second radial projection projecting radially outwardly to form a second shoulder, such that the first and second shoulders are engageable to prevent relative rotation between the first and second body portions. Therefore, the size of the predetermined allowable angle range of the relative rotation can be decided.

According to one embodiment, the second body portion comprises a substantially cylindrical first end section having two second radial protrusions protruding radially outwards. The two protrusions may be arranged to allow a maximum relative rotation of almost 180 deg., for example, before the protrusions hit the corresponding structure. The actual angular range will also depend on the design of the shoulder, wherein the allowable angular range can be reduced with a wider shoulder extending over a larger angle. In some embodiments, a radius may be provided at the transition between the cylindrical body section and the corresponding protrusion, which may be in the range of 0.3-3mm, sometimes 1-2 mm. This has the advantage that a higher strength and durability can be obtained.

In one embodiment, the second body portion comprises a substantially cylindrical first end section having three radially outwardly projecting protrusions. Those skilled in the art will recognize that any other number of protrusions of the respective body portions may be contemplated within the scope of the present description.

According to one embodiment, the second body portion comprises a substantially cylindrical second end section having a diameter equal to the diameter of the first end section and a total radial expansion of two radially outwardly protruding protrusions. The diameter is further preferably adapted to the inner diameter of the cavity formed in the first body part. Further, the total length of the second body portion may be equal to or less than the axial length (i.e. depth) of the cavity, such that the second body portion fits completely within the cavity.

According to one embodiment, the open cavity of the first body part comprises an inner cylindrical surface, and wherein the surface comprises two first radial protrusions protruding radially inwards. Thus, the second body portion may be rotated in the cavity for an angular interval, wherein the end points are defined by inwardly projecting protrusions. Those skilled in the art realize that any other number of protrusions may be envisaged within the scope of the present description.

According to one embodiment, the first shoulder (first radial protrusion) comprises a substantially flat first engagement surface extending in a radial direction and the second shoulder (second radial protrusion) comprises a substantially flat second engagement surface extending in a radial direction, such that the first and second engagement surfaces are contactable along the flat engagement surfaces, thereby providing a mechanical stop limiting the relative rotation. Thus, an effective impact can be advantageously achieved, enabling efficient energy transfer.

In one embodiment, the radial projection extends along 25-75% of the axial length of the body portion, for example, along about half of the axial length of the second body portion. In one embodiment, the second radial projection extends along 25-75% of the axial length of the body portion, for example, along about half of the axial length of the open cavity.

In one embodiment, the expansion unit further comprises a pin rotatably connecting the first body portion and the second body portion. The pins may extend through corresponding holes formed in the first and second body portions. In another embodiment, the first and second body portions rotatably abut one another and rotate in sliding contact. In some embodiments, the extender may include other elements that hold the first and second body portions together, examples of which include a snap ring disposed between two adjacent conforming surfaces of the first and second body portions, respectively. In one embodiment, the snap ring may be disposed on a shoulder (shoulder) or a platform (ridge) formed on the first body portion or the second body portion.

According to one embodiment, the second body portion comprises a rear end portion connected to an output shaft of the power tool, and the first body portion comprises a front end portion adapted to engage with a nipple, which in turn is adapted to engage with a threaded joint. In such embodiments, the second body portion may be rotated within a predetermined allowable angular range when the first body portion is prevented from rotating, i.e. when the nipple engaged therewith is engaged with the threaded fitting (to a tight or near tight engagement). The relative rotation of the second body may for example be performed within a cavity formed in the first body part, in this case in an upper or rear part of the first body part.

According to one embodiment, the first body portion comprises a rear end portion connected to an output shaft of the power tool, and the second body portion comprises a front end portion adapted to engage with a nipple. In such embodiments, the first body portion may be rotated within a predetermined allowable angular range when the second body portion is prevented from rotating, i.e. when the nipple engaged therewith is engaged with the threaded fitting (to a tight or near tight engagement). In this embodiment, the opposing first body portion may include an open cavity formed at a front end thereof, and the second body portion may be partially or fully disposed in the open cavity. In the latter case, the respective front faces of the first and second body portions may lie in the same plane.

According to one embodiment, the permissible range of relative rotation is 50 to 120 °, preferably 90 to 110 °. Smaller or larger values are conceivable within the scope depending on the application.

According to a second aspect of the present invention, there is provided a method of performing a tightening operation with a hand-held power tool in which torque is transmitted in a pulsed manner to tighten a threaded joint, the hand-held power impulse tool including an output shaft, the method comprising the steps of: a first torque pulse is provided on the output shaft in the tightening direction, the output shaft is rotated in a direction opposite to the tightening direction for a predetermined angular interval (which may also be denoted as a predetermined time interval), and a second torque pulse is provided on the output shaft in the tightening direction. In case the expansion unit comprises engagement means arranged to provide a mechanical stop, the angular spacing may be a smaller spacing than the available spacing resulting from the design of these engagement means, thereby avoiding any undesired loosening of the joint.

According to one embodiment, there is provided a method of performing a tightening operation of a hand-held power tool, in which torque is transmitted in pulses to tighten a threaded joint, the hand-held power pulse tool including an output shaft, wherein an expansion unit is provided on the output shaft of the tool and is engaged with a socket (which is in turn engaged with the threaded joint), the method including the steps of: providing a first torque pulse on the output shaft in a tightening direction, rotating the output shaft in a direction opposite to the tightening direction, rotating the first body part relative to the second body part as the second body part engages with the nipple and the nipple in turn engages with the threaded joint, and providing a second torque pulse on the output shaft in the tightening direction, accelerating the first body part within a predetermined allowable angular range before striking the second body part that engages with the nipple which in turn engages with the threaded joint. Thus, the larger and well-defined play provided by the extension piece of the present invention can be exploited, allowing to transfer pulses based on a considerable inertia to the joint, compared to using standard pulse strategies. Rotation in the opposite direction (i.e., the magnitude or length of the reverse motion) may be adapted to the angular range of relative motion provided by the extension member used.

According to a third aspect of the present invention there is provided a hand held power tool for performing a tightening operation in which torque is transmitted in pulses to tighten a threaded joint, wherein the hand held power pulse tool includes an output shaft and is adapted to engage with an extension unit according to any of the above embodiments, the tool being operable to provide a first torque pulse on the output shaft in a tightening direction, to rotate the output shaft in a direction opposite to the tightening direction for a predetermined angular interval, and to provide a second torque pulse on the output shaft in the tightening direction. The tool may be a battery powered tool, may further include a motor and a processor controlling the motor, and may further include a memory containing instructions executable by the processor. Thus, when the processor executes the software instructions, the power tool may operate to perform the steps described above.

According to another aspect of the present invention, there is provided a computer readable storage medium having stored thereon a computer program comprising computer readable code which, when run in a power tool, causes the power tool to perform the method according to any of the above embodiments.

Objects, advantages and features of the power tool and storage medium contemplated within the scope of the third and fourth aspects of the present invention will be readily appreciated by the foregoing discussion with reference to the first and second aspects of the present invention.

Further objects, features and advantages of the present invention will 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 form embodiments other than those described in the following.

Drawings

The invention is described below in detail by way of illustrative and non-limiting description of exemplary embodiments with reference to the attached drawings, in which:

fig. 1 is a longitudinal sectional view of an exemplary extension unit according to a first embodiment.

Fig. 2 is a transverse cross-sectional view of an exemplary expansion unit.

Fig. 3 is a perspective view of a first body portion of an expansion unit according to a first embodiment.

Fig. 4 is a perspective view of a second body portion of an expansion unit according to a second embodiment.

Fig. 5 is a perspective view of a snap ring included in an expansion unit according to a second embodiment.

Fig. 6 shows a flow chart of a method according to an exemplary embodiment of the present invention.

All the figures are schematic, not necessarily to scale and generally show only parts which are necessary for the elucidation of the invention, other parts being omitted or simply mentioned.

Detailed Description

An exemplary expansion unit 1 according to a first embodiment is shown in longitudinal section in fig. 1, which is used with a tightening tool according to the first embodiment. The extension unit 1 comprises a first body part 10 and a second body part 20.

In the embodiment shown, the second body portion comprises a rear end portion 20b for connection to an output shaft of a power tool, while the first body portion 10 comprises a front end portion 10a adapted to engage with a nipple which in turn engages with a threaded joint. In the illustrated embodiment, the rear end portion 20b is adapted to receive a square output shaft of a power tool, while the front end portion 10a is a square output.

The first body part 10 further comprises an open cavity 11 provided at the rear end 10b, the second body part 20 being provided in said open cavity 11. The open cavity is delimited at the upper end of a delimiting wall 11a, said delimiting wall 11a extending through the tubular body 10. Furthermore, the first body part 10 comprises a first end face 12 and the second body part 20 comprises a second end face 22, said first end face 12 and second end face 22 lying in the same plane. Thus, the axial length of the cavity 11 is equal to the axial length of the second body portion, such that the second body portion 20 is fully disposed within the cavity 11.

The second body portion 20 is further arranged in the cavity so as to allow relative rotation between the first and second body portions. Thus, for example, when the first body portion 10 is engaged with a nipple which in turn is engaged with a threaded fitting (tight engagement or near tight engagement, preventing any rotation of the first body portion 10), the second body portion 20 may also be rotated within a predetermined allowable angular range. In the embodiment shown, the expansion unit comprises a pin 30 (e.g. a needle pin 30), said pin 30 rotatably connecting the first body part 10 and the second body part 20, but in other embodiments the second body part 20 may simply rotatably abut a delimiting wall 11a forming the end of the open cavity 11. In the embodiment shown, the allowable range of relative rotation is about 100 °. To further hold the first and second body portions 10, 20 together, a retaining element 40 is provided, which in the illustrated embodiment, the retaining element 40 is a snap ring 40 (shown in fig. 5).

In order to limit such relative rotation, a mechanical stop function is achieved by means of engagement means 13 on the first body portion 10, said engagement means 13 being adapted to engage corresponding engagement means 23 comprised by the second body portion 20, as shown in the cross-section of fig. 2.

In the present embodiment, these engagement means are embodied in the form of radial projections or shoulders. In the first body part 10, two first radial projections (or shoulders) 13a, 13b project radially inwardly, and on the second body part 20, two corresponding second radial projections 23a, 23b form shoulders that project radially outwardly, so that the first and second shoulders can engage to stop relative rotation between the first and second body parts, as shown in fig. 3 and 4. On both sides of the respective bottom of the second radial projections 23a, 23b, i.e. at the transition between the cylindrical portion of the first body part and the projections, a radius R of about 1.5mm is provided.

As can be seen for example from fig. 3 and 4, the shoulder 13 of the first body part 10 is formed on the inner cylindrical surface 11a of the open cavity 11 and extends along about half of the axial length of the open cavity 11, while the second body part comprises a substantially cylindrical end section on which two shoulders (second radial projections 23a, 23b) are provided. Similar to the first body portion, the shoulder (second radial projection 23a, 23b) extends along the axial length of the cylindrical end portion, corresponding to about half the length of the second body portion. Furthermore, each shoulder comprises a substantially flat engagement surface 16, 26 extending in a radial direction, along which the shoulders contact when engaged.

The extension unit according to the described embodiment can advantageously be used with a direct-drive electric tightening tool that performs impulse tightening, i.e. a strategy in which the electric motor transmits torque in the form of pulses to the output shaft. More specifically, when equipped with an extension unit according to the invention provided on the output shaft, a tool constituting another aspect of the invention may be operated to perform a method as shown in fig. 6, the method comprising the steps of: providing a first torque pulse on the output shaft in a tightening direction (S10), rotating the output shaft in a direction opposite to the tightening direction within a predetermined angular interval or time interval, causing the second body part 20 to rotate relative to the first body part 10 as the first body part 10 engages with the nipple and the nipple in turn engages with the threaded joint (tight engagement or tight engagement) (S20), and providing a second torque pulse on the output shaft in the tightening direction, causing the first body part 10 to accelerate within a predetermined allowable angular range before striking the second body part 20 engaged with the nipple (S30), thereby transmitting the torque pulse to the joint.

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 present invention is not limited to the disclosed embodiments. Those skilled in the art will appreciate that many modifications, variations and changes may be made within the scope defined in the appended claims. In addition, 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 shall not be construed as limiting the scope of the claims.

Claims (16)

1. An expansion unit (1) for a power tool adapted to perform a tightening operation, characterized in that the expansion unit (1) comprises

A first body portion (10); and

a second body portion (20);

the first body portion comprising one of a rear end portion (10a) connected to an output shaft of the power tool and a front end portion (20b) adapted to engage with a socket, the second body portion comprising the other of the rear end portion connected to an output shaft of the power tool and the front end portion adapted to engage with a socket;

wherein the second body portion is at least partially disposed in the first body portion, and

allowing relative rotation between the first and second body portions such that when one of the first and second body portions is engaged with the engagement sleeve, the other of the first and second body portions is able to rotate within a predetermined allowed range of angles.

2. Expansion unit (1) for a power tool according to claim 1, wherein the first body part is an at least partly tubular body part and comprises an open cavity (11) provided at a first end of the body part, wherein the second body part is at least partly provided in the open cavity.

3. Expansion unit (1) for a power tool according to claim 1 or 2, wherein the first body part comprises a first end face (12) and the second body part comprises a second end face (22), wherein the first and second end faces lie in the same plane.

4. Expansion unit (1) for a power tool according to claim 1, wherein the first body part comprises engagement means adapted to engage corresponding engagement means comprised by the second body part, thereby providing a mechanical stop limiting the relative rotation.

5. Expansion unit (1) for a power tool according to claim 1, characterized in that the first body part comprises a first radial projection (13 a; 13b) projecting radially inwards to form a first shoulder, wherein the second body part comprises a second radial projection (23 a; 23b) projecting radially outwards to form a second shoulder, such that the first and second shoulders are engageable to prevent relative rotation between the first and second body parts.

6. Expansion unit (1) for a power tool according to claim 5, wherein the second body part comprises a substantially cylindrical first end section (24), the first end section (24) having two second radial protrusions (23 a; 23b) protruding radially outwards.

7. Expansion unit (1) for a power tool according to claim 6, wherein the second body part comprises a substantially cylindrical second end section (25) and a radial expansion of the two radially outwardly protruding protrusions, the diameter of the second end section (25) being equal to the diameter of the first end section.

8. Expansion unit (1) for a power tool according to claim 2, wherein the open cavity of the first body part comprises an inner cylindrical surface (11a), wherein said surface comprises two first radial protrusions (13 a; 13b) protruding radially inwards.

9. Expansion unit (1) for a power tool according to claim 5, wherein the first radial protrusion comprises a substantially flat first engagement surface (16) extending in a radial direction and the second radial protrusion comprises a substantially flat second engagement surface (26) extending in a radial direction, such that the first and second engagement surfaces are contactable along the flat engagement surfaces, providing a mechanical stop limiting the relative rotation.

10. Expansion unit (1) for a power tool according to claim 5, wherein a first radius is provided at the transition between the respective cylindrical body section and the respective protrusion, wherein the radius is in the range of 0.3-3 mm.

11. An extension unit (1) for a power tool according to claim 10, characterized in that the radius is in the range of 1-2 mm.

12. Expansion unit (1) for a power tool according to claim 1, characterized in that the first body part comprises a rear end part (10a) connected to an output shaft of the power tool and the second body part comprises a front end part (20b) adapted to engage with a socket.

13. Expansion unit (1) for a power tool according to claim 1, characterized in that the second body part comprises a rear end part (10a) connected to an output shaft of the power tool and the first body part comprises a front end part (20b) adapted to engage with a socket.

14. Expansion unit (1) for a power tool according to claim 1, characterized in that the allowed range of the relative rotation is 50-120 °.

15. Expansion unit (1) for a power tool according to claim 14, characterized in that the allowed range of the relative rotation is 90-110 °.

16. A hand held power tool for performing a tightening operation characterized by transmitting torque in pulses to tighten a threaded joint, wherein the hand held power pulse tool includes an output shaft and is adapted to engage the expansion unit of claim 1, the tool operating to:

-providing a first torque pulse on the output shaft in a tightening direction;

-rotating the output shaft within a predetermined angular interval in a direction opposite to the tightening direction; and is

-providing a second torque pulse on the output shaft in the tightening direction.

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