EP3983176B1

EP3983176B1 - Hand held power tool

Info

Publication number: EP3983176B1
Application number: EP20733404.6A
Authority: EP
Inventors: Daniel Per Erik Asplund; Jan Olof SJÖHOLM
Original assignee: Atlas Copco Industrial Technique AB
Current assignee: Atlas Copco Industrial Technique AB
Priority date: 2019-06-17
Filing date: 2020-06-16
Publication date: 2023-05-10
Anticipated expiration: 2040-06-16
Also published as: EP3983176A1; WO2020254279A1; CN113993664A

Description

Technical field

The present invention generally relates to hand held power tools. More particularly to such power tools comprising torque multipliers and configured to multiply the torque provided by the motor.

Technical Background

Hand held power tools for tightening are known to be used in various industries, where the size of the screws used varies form very large to very small. Where very large screws are commonly utilized, these also commonly need to be tightened to very high torque levels. The tools used in such fields therefore as such tend to be large and heavy and thus impose considerable strain on an operator handling the tool thus placing high demands on the ergonomics of the tool. Further, in order to provide the high torque levels needed, heavy so called front gear units (also known as torque multipliers) are commonly used, making the weight distribution of such tools shifted towards the front end of the tool and thus making the tool even less ergonomic for the user. Depending on the application, such screws may further be situated in hard to reach position, this being yet another factor negatively influencing the strain on the operator.
One known way of tightening screw located in a hard to reach position is to extend the output shaft of the tool, with an extender. However, given the high torques delivered by such tools, the extension needs to withstand high torque levels, which makes the extension heavy. The high torque levels also makes it necessary to use a reaction arm. The reaction arm needs to be positioned at the power tool. This is associated with a considerable safety hazard, since the hand of the operator risk getting squeezed or pinched between the reaction arm and work piece. Hence there exists a need for improvement in the field of such hand held power tools. Such a tool, disclosing the preamble of claim 1, can be seen in document WO 2018/232067 A1 .

Summary of the invention

Accordingly, it would be desirable to provide a design enabling lower weight of the tool imposing less strain on the operator of the tool. In particular, it would be desirable to provide such a design which also improves reach of screws located in hard to reach positions. To better address one or more of these concerns a hand held power tool as defined in the independent claim is provided. Preferred embodiments are defined in the dependent claims.
According to a first aspect of the disclosure a hand held power tool is provided. The hand held power tool comprising a motor housing in which a rotor of a motor defines an axial direction. The hand held power tool further comprising a torque multiplier unit extending in the axial direction. An extension unit arranged to extend in the axial direction and attached between the motor housing at a front end thereof and the torque multiplier unit at a back end thereof, the extension unit drivingly connects the rotor to an input axis of the torque multiplier unit. Thus the motor housing encloses the motor, not the extension unit and the torque multiplier unit.
According to the first aspect, the handheld power tool provides an inventive solution to the concerns described above by means of a design incorporating an extension unit attached between the motor housing at a front end thereof and the torque multiplier unit at a back end thereof. Since the extension unit is attached between the motor housing and the torque multiplier the extension unit can be made much lighter since the extension unit does not need to withstand high torque levels. Thus significantly reducing the weight of the power tool.
The power tool according to the invention therefore cleverly provides improved ergonomics as well as improved safety by means of the provision of one inventive structure, i.e. the inventive extension unit attached between the motor housing and the torque multiplier, thus reducing weight and the need for a reaction bar close to the motor housing of the tool. This since the weight and diameter of the extended unit can be reduced. And that the reaction bar can be provide close to the screw joint instead of close to the motor housing of the power tool, as in prior art solutions.
Hence, the inventive design of the power tool according to independent claim 1 cleverly solves both the problem of high weight and safety, this in a manner reducing complexity and weight of the tool.
The referenced hand held power tool may for example be a pistol nut runner, for example an electric pistol nut runner. The hand held 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. In one embodiment, this reaction arm may be arranged at the front end of the torque multiplier unit. The torque multiplier unit may be a swiveling torque multiplier.
According to one embodiment, the extension unit is manufactured in a light weight material. This allows for further reducing the weight of the extension unit and thus of the power tool.
According to one embodiment, the light weight material is aluminum. According to another embodiment, the light weight material is composite. Hereby the weight of the extension unit is kept low. The extension unit also becomes strong enough to withstand impacts and withstand damage in case the power tool is dropped.
According to one embodiment, the length of the extension unit is above 250 mm. Herby the power tool can be used to tighten screws located at hard to reach positions. For example, in such an embodiment, the power tool can be used to reach a wheel nut inside a wheel rim of a larger type of vehicle. Such as a mine truck, or any other type of larger vehicle.
According to one embodiment, the extension unit drivingly connects the rotor to the input axis of the torque multiplier unit without gearing. Hereby, the extension unit can be made less complex, bulky and heavy. Actually no gearing is needed in the extension unit since the extension unit only transfers a low torque value from the rotor to the input of the torque multiplier unit.
According to one embodiment, the extension unit comprising a supporting handle structure extending in the axial direction in order to allow a user to support the tool at the extension unit. Herby the operator can more easily carry the power tool. According to one embodiment the supporting handle structure is of a spade handle type extending in a direction perpendicular to the axial direction.
According to one embodiment, the tool may be a so called pistol type tool and the handle of the motor housing may be described as a pistol handle extending at the specified circumferential position in what may, in use, be described as a position under or on an underside of the motor housing. In such an embodiment, a user may carry the tool using a spade type of handle arranged on the extension unit. According to one embodiment, the spade type of handle is arranged at circumferential position 180 degrees from the circumferential position of the pistol type of handle under the motor housing.
According to one embodiment, the supporting handle comprises an elongated gripping portion adapted to support a hand of an operator.
According to one embodiment the extension unit is circularly shaped. Hereby the extension unit can be made lighter and at the same time strong enough to withstand chocks and don't break in case the power tool is dropped. According to one embodiment, a mid section of the extension unit is adapted to fit a palm of a hand of an operator. Such a shape increases ergonomics for the user even further.
According to one embodiment the diameter of the extension unit is substantially smaller than the diameter of the torque multiplier unit. Hereby the weight of the hand held power tool can be kept low. Another advantage with the diameter of the extension unit being substantially smaller than the diameter of the torque multiplier unit is that the hand held power tool can be used to tightening wheel nuts on large vehicles. Wheel rims on large vehicles often have a reinforcement edge inside the wheel rim. This reinforcement edge would make it impossible to tighten the wheel nut in case the extension unit did not have a substantially smaller diameter than the diameter of the torque multiplier unit.
According to one embodiment, the extension unit is telescopic so that the length of the extension unit can be changed. Herby the length of the power tool can easily be adapted to different types of tightening situations. Since the extension unit only has to withstand low torque values it is possible to make the extension unit telescopic. A situation where this is advantageous is when tightening wheel nuts located inside deep wheel rims. Since the depth of different types of wheel rims are different it is advantageous to be able to change the length of the power tool so that the operator's hands always are located outside the rim.
Also, as mentioned above when tightening to high torque levels a reaction bar is needed. The reaction bar needs to be supported somewhere at the object at which the tightening is performed. In prior art solutions where the output shaft was extended it is often hard to find a suitable location for supporting the reaction bar. According to the present disclosure it is however possible to located the reaction bar at the front of the torque multiplier unit and with the extension unit extend the power tool so that the motor housing is located at a position where it is suitable for an operator to operate the power tool.
According to one embodiment, wherein the extension unit is telescopic, the telescopic extension unit comprising a tubular front section and a tubular back section.
According to one embodiment, the diameter of the tubular front section is smaller than a dimeter of the tubular back section. Hereby the tubular front section can slide inside the tubular back section, and thereby can the length of the telescopic extension unit can be changed.
According to one embodiment, the diameter of the tubular front section is larger than a dimeter of the tubular back section. Hereby the tubular back section can slide inside the tubular front section, and thereby can the length of the telescopic extension unit can be changed.
According to one embodiment, the tubular back section comprising interlocking elements to prevent the tubular front section and the tubular back to move with respect to each other.
According to one embodiment, the hand held power tool is configured to deliver a torque in the range 200-80000 Nm. The advantages of the inventive extension unit design are of particular importance as the torque delivered, and hence the weight of the torque multiplier unit and the potential weight increases.
According to one embodiment, the motor housing further comprising a gearing between the rotor and the output axis. Hereby the rotation speed of the output axis can be optimized.
According to one embodiment the input axis of the torque multiplier unit and the output axis from the motor is hexagonal. Herby the rotor and the input axis of the torque multiplier unit can be rotationally locked with respect to each other.
According to one embodiment the input axis of the torque multiplier unit and the output axis from the motor is octagonal. Herby the rotor and the input axis of the torque multiplier unit can be rotationally locked with respect to each other.
Further objectives of, features of 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 create embodiments other than those described in the following.

Brief description of the drawing

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 side view of an exemplary hand held power tool according to one embodiment.
Figure 2 is a side view of an exemplary hand held power tool 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.

Detailed description

Figure 1 illustrates an exemplary hand held power tool in a side view. The illustrated embodiment being an air powered pistol type nut runner comprising a motor housing 10 in which a motor coupled to an outgoing shaft defining an axial direction A-A is arranged. The torque multiplier unit 20 extends in the axial direction A-A. An extension unit 30 is arranged to extend in the axial direction A-A. The extension unit 30 is attached between the motor housing 10 at a front end 10a thereof and the torque multiplier unit 20 at a back end 20b thereof. The extension unit 30 comprising an axis 40 which drivingly connects the rotor (not shown) to an input axis 45 of the torque multiplier unit 20. Thus the motor housing 10 encloses the motor, not the extension unit 30 and the torque multiplier unit 20.
The illustrated example tool is configured to deliver a torque in the range 260-4000 Nm
In the exemplary hand held power tool 1 shown in figure 1, the length of the extension unit can be 480 mm. However the disclosure is not limited to this length. The extension unit can be shorter or longer. According to one embodiment the length of the extension unit is above 250 mm.
In the shown hand held power tool 1, the extension unit 30 drivingly connects the rotor (not shown) to the input axis 45 of the torque multiplier unit 20 without gearing.
In the shown hand held power tool 1, the extension unit 30 is circularly shaped. Also, as shown in figure 1 the diameter of the extension unit 30 is adapted to be supportable by a hand of an operator.
Figure 2 illustrates another exemplary embodiment of a hand held power tool 1 wherein the extension unit 30 is telescopic so that the length of the extension unit 30 can be changed. The illustrated embodiment being an air powered pistol type nut runner comprising the motor housing 10 in which the motor coupled to the outgoing shaft defining the axial direction A-A is arranged. The torque multiplier unit 20 extends in the axial direction A-A. The extension unit 30 is arranged to extend in the axial direction A-A. The extension unit 30 is attached between the motor housing 10 at the front end 10a thereof and the torque multiplier unit 20 at a back end 20b thereof. In this embodiment the extension unit comprising a tubular front section 30b and a tubular back section 30a. The tubular back section 30a comprising a hollow shaft 45 which drivingly connects the rotor (not shown) to an axis 46 of the tubular front section 30b. The axis 46 of the tubular front section 30b is drivingly connected to the input axis 45 of the torque multiplier unit 20. Thus the motor housing 10 encloses the motor, not the extension unit 30 and the torque multiplier unit 20.
In the embodiment illustrated in figure 2 the diameter of the tubular front section 30b is smaller than a dimeter of the tubular back section 30a. In order to prevent the tubular front section 30b and the tubular back section 30a to move with respect to each other the extension unit 30 comprising a threaded locking ring 31 and a wedge shaped locking ring 32. In the embodiment illustrated in figure 2 the inner surface at a front part of the tubular back section 30a is wedge shaped so that a wedge shaped locking ring 32 can lock the tubular front section 30b and the tubular back section 30a from moving with respect to each other. In the power tool 1 illustrated in figure 2 the tubular back section 30a is threaded at the front part. Herby the threaded locking ring 31 can press the wedge shaped locking ring 32 backwards in order to lock the tubular front section 30b and the tubular back section 30a from moving with respect to each other.
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

A hand held power tool (1) comprising:
a motor housing (10) in which a rotor of a motor defines an axial direction (A-A);

a torque multiplier unit (20) extending in the axial direction (A-A), the hand held power tool further comprising:
an extension unit (30) arranged to extend in the axial direction (A-A) characterised in that the extension unit (30) is attached between the motor housing (10) at a front end (10a) thereof and the torque multiplier unit (20) at a back end (20b) thereof, and in that the extension unit (30) drivingly connects the rotor to an input axis (40) of the torque multiplier unit (20).
The hand held power tool (1) according to claim 1, wherein the extension unit (30) is manufactured in a light weight material.
The hand held power tool (1) according to claim 2, wherein the light weight material is aluminum.
The hand held power tool (1) according to any of the preceding claims, wherein the length of the extension unit is above 250 mm.
The hand held power tool (1) according to any of the preceding claims, wherein the extension unit drivingly connects the rotor to the input axis of the torque multiplier unit (20) without gearing.
The hand held power tool (1) according to any of the preceding claims, wherein the extension unit comprises a supporting handle structure extending in the axial direction in order to allow a user to support said tool at the extension unit.
The hand held power tool (1) according to claim 6, wherein the supporting handle comprises an elongated gripping portion (42) adapted to support a hand of an operator.
The hand held power tool (1) according to any of the preceding claims, wherein the extension unit is circularly shaped.
The hand held power tool (1) according to any of the preceding claims, wherein a mid-section of the extension unit is adapted to be supportable by a hand of an operator.
The hand held power tool (1) according to any of the preceding claims, wherein the diameter of the extension unit is substantially smaller than the diameter of the torque multiplier unit (20).
The hand held power tool (1) according to any of the preceding claims, wherein the extension unit (30) is telescopic so that the length of the extension unit can be changed.
The hand held power tool (1) according to claim 11, wherein the telescopic extension unit comprising a tubular front section (30b) and a tubular back section (30a).
The hand held power tool (1) according to claim 12, wherein the diameter of the tubular front section (30b) is smaller than a dimeter of the tubular back section (30a).
The hand held power tool (1) according to claim 12, wherein the diameter of the tubular front section (30b) is larger than a dimeter of the tubular back section (30a).
The hand held power tool (1) according to any of claims 12 to 14, wherein the tubular back section (30a) comprising interlocking elements (31, 32) to prevent the tubular front section (30b) and the tubular back section (30b) to move with respect to each other.