WO2014001072A2

WO2014001072A2 - Power tool and a handle of a pneumatic power tool

Info

Publication number: WO2014001072A2
Application number: PCT/EP2013/061948
Authority: WO
Inventors: Anders Urban Nelson; Nabil Khalil Radif
Original assignee: Atlas Copco Industrial Technique AB
Current assignee: Atlas Copco Industrial Technique AB
Priority date: 2012-06-27
Filing date: 2013-06-11
Publication date: 2014-01-03
Anticipated expiration: 2014-12-27
Also published as: WO2014001072A3

Description

Power tool and a handle of a pneumatic power tool

The invention relates to a pneumatic power tool and particularly to a handle of such a power tool.

Background

A conventional pneumatic power tool, such as e.g. a drilling tool, comprises a grip portion inside which a valve is arranged. A lever is arranged on the outside of the grip portion for controlling the valve.

Conventionally, the handle is produced in aluminium and the lever is produced in a harder steel material. Often, the lever is attached to the handle via a fastening arrangement that includes a steel pin that is arranged through the periphery of the handle. In order to minimise the diameter of the handle the steel pin is normally relatively thin with a diameter of about 1-2 mm. Even so, an increased thickness of the handle that will build on its diameter will be needed. This is not wanted because the thickness should be kept as small as possible in order to maximise the inner diameter with respect to the outer diameter, and because it is desired to keep the material consumption as low as possible.

Another problem with such a conventional fastening arrangement is that it often degrades over time. This is partly due to the fact that the aluminium is more resilient than the steel pin, such that the steel pin will be allowed to move about in the holes through the handle. The irregular movement of the steel pins will eventually plastically deform the holes such that they will become wider. The degradation may then accelerate to a point where the pivoting function is so poor that the handle needs to be exchanged.

Hence, there is a need for a handle with an improved type of fastening arrangement, which will be more stable than conventional fastening arrangements and less prone to

degradation .

Summary of the invention

An object of the invention is to provide a handle for a

pneumatic power tool that has more stably attached lever.

This object is achieved by the invention according to the independent claims .

According to a first aspect the invention relates to a handle for a pneumatic power tool, which handle comprises:

a tool attachment portion to which a tool part is to be attached;

an air inlet portion for connection to an air supply, an elongate grip portion arranged between the tool attachment portion and the elongate grip portion, the elongate grip portion being adapted to be held by at least one hand of an operator;

an internal air duct running inside the handle from the air inlet portion to the tool attachment portion for conveying pressurized air there between;

a lever, which is pivotally mounted along said grip portion, and which is arranged to control the opening of a valve in connection to said internal air duct. Preferably, the valve is in an open position when the lever is pressed towards the grip portion of the handle and in a closed position when the lever is left unaffected in a separated position with respect to the handle. The handle includes two holes and in that the lever is pivotally mounted to the outside of the handle around two steel dowels that are arranged to extend through said holes from an interior of the handle to the outside of the handle, wherein an outer part of each hole has a first diameter, and wherein each dowel includes a cylindrical portion and a foot portion, wherein the cylindrical portion has a similar or minor diameter than said first diameter of the outer part of the holes and is adapted to extend through said outer part, and wherein the foot portion has a geometry that prevents the dowels to pass outwards through said outer part of the holes .

According to a second aspect the invention relates to a power tool, including a handle as described above, and a tool part.

An advantage of the invention according to these two aspects is that a stable force interaction is created between the foot portions of the dowels and the core material of the elongate grip portion. This interaction guarantees a stable connection between the steel dowels and the core material of the elongate grip portion. Further, the interaction will be less prone to fatigue due to the close contact between the steel dowels and the core material of the elongate grip.

Also, the use of separate steel dowels to support the lever, instead of one steel pin that passes through the periphery of the handle, increases the flexibility of where the lever may be mounted. For instance, the lever may be pivoted on opposite sides of the handle without having anything interfering with the duct inside the handle. Preferred embodiments and other advantages thereof will be apparent from the detailed description and from the dependent claims .

Short description of the drawings

In the following detailed description reference is made to the accompanying drawings, of which:

Fig. 1 shows a side view of a tool handle according to an embodiment of the invention;

Fig. 2 shows a perspective view of the tool handle shown in fig. 1; Fig. 3 shows a sectional view of a tool handle according to a first embodiment of the invention;

Fig. 4 shows a detailed view of the encircled part IV in fig. 3;

Fig. 5 shows a sectional view of a tool handle according to a second embodiment of the invention;

Fig. 6 shows a detailed view of the tool handle shown in fig. 5; and

Fig. 7 shows a perspective view of a steel dowel in accordance with the second embodiment of the invention.

Detailed description of one embodiment of the invention

In figs. 1 and 2 a handle 10 for a pneumatic power tool

according to a specific embodiment of the invention is shown. At a front end the handle 10 comprises a tool attachment portion 11 to which a tool part is to be attached. At a rear end the handle 10 comprises an air inlet portion 12 for connection to an air supply hose.

An elongate grip portion 13 is arranged between the tool attachment portion 11 and the air inlet portion 12. The elongate grip portion 13 is adapted to be held by at least one hand of an operator. The elongate grip portion 13 may be made of an aluminium based metal, such as pure aluminium or an alloy based on aluminium, or a magnesium based material, or a plastic material. In the two exemplary embodiments below the elongate grip portion 13 is made of an aluminium based metal. This is however only an example, and the invention is not limited to an aluminium material.

A lever 14 is pivotally mounted along said grip portion 13. The lever 14 is attached to the handle by means of two steel dowels 17 of a specific diameter. The steel dowels 17 are arranged in holes on opposite sides of the handle 10, the holes having a diameter that matches the specific diameter of the steel dowels 17.

An internal air duct 15 is arranged inside the handle 10 and runs from the air inlet portion 12 to the tool attachment portion 11 for conveying pressurized air there between.

As is visible in figures 3 and 5 a valve 16 is located inside the internal duct 15 for selectively opening or closing said internal air duct 15. The pivotally mounted lever 14 is arranged to control the opening of the valve 16, such that the valve 16 is in an open position when the lever 14 is pressed towards the grip portion 13 of the handle 10 and such that the valve 16 is in a closed position when the lever 14 is left unaffected in a separated position with respect to the handle 10.

Below, two different embodiments of the invention will be described. Firstly, the first embodiment, which is shown in figures 3 and 4, will be described.

The holes include an exterior portion 24 that has a first diameter di . Each dowel 17 includes a foot portion 18 of a geometry that prevents the dowels 17 to pass outwards through an outer part 24 of the holes. In the shown embodiment, the foot portion 18 has the form of a foot flange with a diameter d₂ that exceeds the diameter di of the exterior portion 24 of the holes, the foot flange being located on the inside of the holes so as to prevent the steel dowels 17 to pass through the holes, and so as to increase the active surface of the force transmission between the steel dowels 17 and the core material of the elongate grip portion 13. A cylindrical portion 19 of the steel dowels has a similar or minor diameter than said first diameter di, and said cylindrical portion 19 is adapted to extend through the exterior part 24 of the holes. In another not shown embodiment the foot portion 18 is bent with respect to the cylindrical portion 19, which bent portion will prevent the steel dowels 17 to pass through the holes.

In the shown embodiment, the steel dowels 17 are integrated in the aluminium based metal of the elongate grip portion 13, such that a base portion of each steel dowel 17 including the flange shaped foot portions 18 is embedded in the core material of the elongate grip portion 13. This is preferably achieved in that the steel dowels are casted into the aluminium based metal.

Therefore, the casting operation includes a first step where the steel dowels 17 are positioned in a mould into which the aluminium based metal is to be casted. Hence, when the aluminium based metal is provided into the mould it will embed the steel dowels 17 into the aluminium based metal of the elongate grip portion 13.

The steel dowels 17 include a protrusion 25 below the foot portion 18. The protrusion 25 is useful to keep the steel dowel 17 at place during the casting process, during which the protrusion 25 will abut a central cylindrical part of the mould. In the shown embodiment an air filter 20 is arranged inside the grip portion 13 of the handle 10. The filter 20 is fastened by means of a filter housing 21 that is arranged to bear tightly against the inside of the grip portion. A sealing 22, e.g. in the form of an O-ring is arranged between the filter housing 21 and the inside of the grip portion 13, in order to make sure that no air may slip through outside the filter housing 21. The filter housing may be made of a plastic material.

A second embodiment of the invention is shown in figures 5 and 6. In this second embodiment features that differ from the corresponding features of the first embodiment have been denoted with an apostrophe (^Λ) . In the second embodiment, the holes on the handle 10 are arranged as through holes that are provided near the tool attachment portion 12, such that the steel dowels 17' will bear against a connection portion 23' of a tool part (not shown) when the handle 10 is attached to said tool part. It may be noted that the connection portion 23' of the second embodiment differs from the connection portion 23 of the first embodiment in that it extends further into the tool attachment portion 11 'of the handle 10. The tool attachment portion 11 'of the handle 10 of course differs in a corresponding manner in order to match the connection portion 23' of the tool part.

The steel dowels 17' of this second embodiment include a foot portion 18' of a wider diameter than the cylindrical body 19 of the steel dowel 17'. As is visible in fig. 7, the foot portion 18' has a concave lower surface, which is arranged to bear against the outer cylindrical surface of the connection portion 23' of the tool part. This abutment of the foot portion 18' of the steel dowel 17' to the connection portion 23' of the tool part is made possible by the fact that the connection portion 23' in this second embodiment extends sufficiently far into the tool attachment portion 11'.

Hence, in the mounting of the connection portion 23 of the tool part to the tool attachment portion 11' of the handle 10, the steel dowels 17' need to be correctly positioned before the connection portion 23' of the tool part is inserted into the tool attachment portion 11' of the handle 10. The steel dowels 17' are inserted from the inside through the holes in the elongate grip portion 13.

In order for the steel dowels 17' to be as tightly fastened as possible the gaps surrounding the steel dowels 17' should be as small as possible. Hence, the steel dowels 17' should be machined to fit both the tool attachment portion 11' of the handle and the connection portion 23' of the tool part as tightly as possible.

A further advantage of the handle according to the invention is that the steel dowels 17, 17' of both embodiments are shallow such that they do not extend into the interior of the handle 10. This gives the advantage that they may be located at any place around the periphery of the handle 10. In the prior art, the lever is normally pivoted at the periphery of the handle. With the inventive shallow shape of the dowels 17, 17', the lever may be pivoted at opposite sides of the handle, which is

advantageous from a force distribution point of view. In an optimal embodiment the dowels are arranged at opposite sides of the handle 11, approximately 180° apart. In order to obtain a good force distribution, the dowels should be located at least approximately 180° apart around the handle.

Above, the invention has been described with reference to two specific embodiments. The invention is however not limited to either of these embodiments. Instead the scope of the invention is defined by the following claims.

Claims

1. A handle (10) for a pneumatic power tool, which handle

(10) comprises:

- a tool attachment portion (11, 11') to which a tool part is to be attached;

an air inlet portion (12) for connection to an air supply, an elongate grip portion (13) arranged between the tool attachment portion (11) and the elongate grip portion (13), the elongate grip portion (13) being adapted to be held by at least one hand of an operator;

an internal air duct (15) running inside the handle (10) from the air inlet portion (12) to the tool attachment portion

(11) for conveying pressurized air there between;

- a lever (14), which is pivotally mounted along said grip portion (13), and which is arranged to control the opening of a valve (16) in connection to said internal air duct (15),

characterised in that the handle (10) includes two holes and in that the lever (14) is pivotally mounted to the outside of the handle (10) around two steel dowels (17, 17') that are arranged to extend through said holes from an interior of the handle (10) to the outside of the handle (10), wherein an outer part (24) of each hole has a first diameter ( di ) , and wherein each dowel (17, 17') includes a cylindrical portion (19) and a foot portion (18, 18'), wherein the cylindrical portion (19) has a similar or minor diameter than said first diameter ( di ) of the outer part (24) of the holes and is adapted to extend through said outer part (24), and wherein the foot portion (18, 18') has a geometry that prevents the dowels (17, 17') to pass outwards through said outer part (24) of the holes.

2. The handle (10) according to claim 1, wherein the steel dowels (17, 17') are shallow so as to not extend into the duct (15) inside the handle (10) .

3. The handle (10) according to claim 2, wherein the foot portions (18, 18') of the steel dowels (17, 17') are formed as foot flanges with an increased diameter with respect to the cylindrical portions (19) of the steel dowels (17, 17') .

4. The handle (10) according to claim 3, wherein the steel dowels (17) are embedded in the core material of the handle (10), such that the cylindrical portions (19) of the respective steel dowels (17) extend through the holes to the outside of the tool handle (10) while the foot portions (18) are embedded in the core material of the handle (10) .

5. The handle (10) according to claim 1 or 2, wherein the holes on the handle (10) are through holes that are arranged at the tool attachment portion (11), such that steel dowels (17') will bear against a connection portion (23' ) of a tool part when attached to said tool part.

6. The handle (10) according to claim 5, wherein the foot portions (18') of the steel dowels (17') are formed as foot flanges with an increased diameter with respect to the

cylindrical portions (19), and wherein the foot flanges will bear against the connection portion (23' ) of the tool part when the handle is attached to said tool part.

7. The handle (10) according to claim 6, wherein the foot portion (18') of the steel dowels (17') has a concave lower surface that will bear against the connection portion (23' ) of the tool part when attached to said tool part.

8. The handle (10) according to any of the preceding claims, wherein the holes on the handle (10) are arranged at least 120 degrees apart around the handle (10) .

9. The handle (10) according to claim 8, wherein the holes on the handle (10) are arranged about 180 degrees apart on opposite sides of the handle (10) .

10. A power tool comprising a tool part and a handle (10) according to any of the preceding claims .