GB2429420A

GB2429420A - Handheld power tool

Info

Publication number: GB2429420A
Application number: GB0517455A
Authority: GB
Inventors: Jing Ning Ta; James Ching Sik Lau
Original assignee: Johnson Electric SA
Current assignee: Johnson Electric SA
Priority date: 2005-08-26
Filing date: 2005-08-26
Publication date: 2007-02-28
Also published as: GB0517455D0

Abstract

A handheld power tool 10 comprises a body 12; a driving mechanism 16; and a head 14 which is supported by the body 12 for pivotable movement about a pivot axis P. The head 14 includes a tool portion 32, which is rotatably drivable by the driving mechanism 16. The driving mechanism 16 includes a drive motor 18 housed in the body 12, a driving bevel gear 36 provided on or in the body 12 and drivable by the drive motor 18, a driven bevel gear 38 provided on the head 14 for driving the tool portion 32 and which is spaced from the driving bevel gear 36, and a torque-transmitting bevel gear 40 which is mounted for rotation on the pivot axis P of the head 14 and which engages both the driving and driven bevel gears 36, 38 for transmitting a driving torque therebetween.

Description

HANDHELD POWER TOOL

The present invention relates to a handheld power tool having a pivotable head.

A handheld power tool having a pivotable head is well known. The pivotable head is particularly convenient since it allows the tool to access narrow or confined spaces which would typically be unreachable with a conventional fixed-head tool.

However, a driving mechanism for the tool which transmits torque to the head through an adjustable angle is often bulky, requiring many components. It is often the driving mechanism and, in particular, the torque transmission assembly which limits the access of the tool to a confined space.

The present invention seeks to provide a solution to this problem by providing a more compact power tool.

According to the present invention, there is provided a handheld power tool comprising: a body; a driving mechanism; and a head which is pivotably supported by the body for movement about a pivot axis, and which includes a tool portion which is rotatably drivable by the driving mechanism, the driving mechanism including a drive motor housed in the body, a driving bevel gear supported on or in the body and drivable by the drive motor, a driven bevel gear supported by the head for driving the tool portion and which is spaced from the driving bevel gear, and a torque-transmitting bevel gear which is mounted for rotation on the pivot axis of the head and which engages both the driving and driven bevel gears for transmitting a driving torque therebetween.

Preferable and/or optional features of the invention are set forth in claims 2 to 12, inclusive.

The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of one embodiment of a handheld power tool, in accordance with the present invention, with a pivotable head in a first condition, and with a battery pack removed; Figure 2 is a view similar to Figure 1, but with the head of the handheld power tool in a second condition; Figure 3 is an enlarged cutaway view of part of the handheld power tool shown in Figure 1, showing part of a driving mechanism; and Figure 4 is a longitudinal sectional view of the handheld power tool with battery pack attached.

Referring to the drawings, there is shown a handheld power tool 10 which comprises a, typically cylindrical, body 12 adapted to be gripped by a user's hand, a head 14 which is supported for pivotable movement at one end of the body 12, and a driving mechanism 16.

The driving mechanism 16 includes an electric drive motor 18 (Figure 4) housed in the body 12, and a torque adjustment mechanism 20 for adjusting and/or limiting a driving torque produced by the drive motor 18. The torque adjustment mechanism 20 has a manual adjustment element 22 at one end of the body 12 opposite the head 14 so that a user can manually set a maximum torque to be produced by the drive motor 18.

The torque adjustment mechanism 20 itself is well known, and thus further detailed

description is omitted.

The electric drive motor 18 is typically battery operated, and a, preferably rechargeable, battery pack 23 having an ON / OFF switch 23 is typically releasably connectable to the end of the body 12 adjacent the torque adjustment mechanism 20, as shown in Figure 4.

Obviously, however, a battery or battery pack could be removably locatable within the body 12. Furthermore, the drive motor 18 could be, additionally or alternatively, mains operated.

The end of the body 12 adjacent the head 14 includes a recess 24 in which a pair of parallel arms 26 of the head 14 is received. Each arm 26 is pivotably connected to the body 12 through a wall 28 defining the recess 24. As will be appreciated from Figure 1, this allows the head 14 to pivot through 90 degrees about a pivot axis P, with the wall 28 acting as a stop.

By recessing a portion of the wall 28, and/or by providing a suitable stop, the head 14 can be allowed to pivot through a greater or lesser range of angles, for example up to but not beyond 120 degrees, up to but not beyond 150 degrees, or up to but not beyond 180 degrees.

Although Figure 3 depicts the present embodiment of the invention, from the cutaway it will be appreciated that, in a modification, the wall 28 defming the recess 24 can be completely replaced by a second pair of parallel extending arms 30 formed as part of the body 12 and to which the arms 26 of the head 14 are pivotably connected.

This arrangement allows the head 14 to pivot through 180 degrees about the pivot axis P. As shown in Figure 4, a push-button locking mechanism 31 having a user operable push button 31 is provided on the body 12 at the pivot axis P. The locking mechanism 31 prevents pivoting of the head 14, until a user releases the locking mechanism 31 by depressing the button 3 1. The locking mechanism 31 also allows the head 14 to be locked at varying degrees of angulation from a condition in which the head 14 is rectilinearly aligned with the body 12, which, for the sake of clarity, is assumed to be 0 degrees offset. For example, the head 14 can be locked at 0 degrees (i.e. aligned with the body 12), 15 degrees, 30 degrees, 60 degrees, and 90 degrees offset relative to the body 12. These angles of locking apply in the case in which the head 14 is pivotable only in a single direction from the 0 degrees aligned condition, and in the case when the head 14 is pivotable in two directions from the 0 degrees aligned condition.

Other arrangements for retaining the head 14 at a particular angular offset are also envisaged. For example, a resilient click-lock mechanism can be used, in which small projections formed on outer facing surfaces of the arms 26 of the head 14 cooperate with complementarily-shaped indentations formed on an inwardly facing surface of the wall 28 of the recess 24 or the arms 30 of the body 12 to retain the head 14 at a given position.

The head 14 includes a tool portion 32 which is rotatable about a drive axis D extending perpendicularly to the pivot axis P of the head 14. The tool portion 32 is of any known suitable form, and, for example, is adapted to receive as a push fit a tool bit, such as a screwdriver bit 34 as shown in the drawings, or can include a chuck for clamping various sizes of bit, such as drill bits.

The driving mechanism 16 has a driving bevel gear 36 mounted for rotation at the end of a drive shaft 18, adjacent to the wall 28 of the recess 24. The drive shaft 18, is coupled to an output shaft 1 8 of the drive motor 18 via a gear reduction mechanism 1 8c. However, the gear reduction mechanism 1 8 can be dispensed with, and the bevel gear 36 can be mounted directly on the end of the output shaft 1 8h.

A driven bevel gear 38 of the driving mechanism 16 is mounted on the head 14 for rotating the tool portion 32. The driving and driven bevel gears 36 and 38 are spaced apart, and the driven bevel gear 38 and tool portion 32 are coaxial.

An idle or torque-transmitting bevel gear 40 of the driving mechanism 16 is mounted for rotation on the pivot axis P, adjacent to the inwardly facing surface of one of the arms 26 of the head 14. The torquetransmitting bevel gear 40 simultaneously meshes with both the driving and driven bevel gears 36 and 38, and thus, in use, transmits a driving torque from the driving bevel gear 36 to the driven bevel gear 38, which causes the tool portion 32 and associated bit 34 to rotate.

The torque-transmitting bevel gear 40 has a diameter which is larger than the diameters of the driving and driven bevel gears 36, 38, thereby preventing direct meshing or engagement of the driving and driven bevel gears 36, 38 when the head 14 is pivoted. In particular, without the enlarged torque-transmitting bevel gear 40, pivoting of the head 14 to and beyond 90 degrees from a condition in which the head 14 is rectilinearly aligned with the body 12 will result in the driving and driven bevel gears 36, 38 directly meshing with each other. However, if the head 14 is prevented from pivoting to an extent whereby meshing of the driving and driven bevel gears 36, 38 occurs, then the torque-transmitting bevel gear 40 can have the same diameter as the driving and driven bevel gears 36, 38, or possibly even a smaller diameter.

In a modification to the embodiment described above, a second torquetransmitting bevel gear is mounted for rotation on the pivot axis P, adjacent the inwardly facing surface of the other arm of the head and opposite the first said torque- transmitting bevel gear. This arrangement is beneficial in that it allows a greater driving torque to be transmitted between the driving and driven bevel gears without slipping or damage to the driving mechanism.

The use of bevel gears enables an extremely compact driving mechanism to be realised, allowing the head size to be reduced considerably. Consequently, the handheld power tool can operate in smaller and more confmed spaces than has heretofore been possible. The head can be pivoted simultaneously with the rotation of the tool portion.

The embodiments described above are given by way of examples only, and modifications will be apparent to persons skilled in the art without departing from the scope of the invention as defmed by the appended claims. For example, although the tool bit is releasable, the bit may be permanently attached to the tool portion.

Claims

1. A handheld power tool comprising: a body; a driving mechanism; and a head which is pivotably supported by the body for movement about a pivot axis, and which includes a tool portion which is rotatably drivable by the driving mechanism, wherein the driving mechanism includes a drive motor housed in the body, a driving bevel gear provided on or in the body and drivable by the drive motor, a driven bevel gear provided on the head for driving the tool portion and which is spaced from the driving bevel gear, and a torque-transmitting bevel gear which is mounted for rotation on the pivot axis of the head and which engages both the driving and driven bevel gears for transmitting a driving torque therebetween.

2. A handheld power tool as claimed in claim 1, further comprising a second torque-transmitting bevel gear which is mounted for rotation on the pivot axis opposite the first said torque-transmitting bevel gear, the second torque-transmitting bevel gear engaging both the driving and driven bevel gears for transmitting a driving torque therebetween.

3. A handheld power tool as claimed in claim 1 or claim 2, wherein, at least when the head is pivotable through 90 degrees from a condition in which the head is aligned with the body, the or each torque-transmitting bevel gear has a diameter which is larger than that of the driving and driven bevel gears so as to prevent direct engagement of the driving and driven bevel gears when the head is pivoted.

4. A handheld power tool as claimed in any one of the preceding claims, further comprising a torque adjustment mechanism for adjusting and/or limiting a driving torque imparted to the driving bevel gear by the drive motor.

5. A handheld power tool as claimed in claim 4, wherein the torque adjustment mechanism includes a manual adjustment element for setting a driving torque of the drive motor and which is operable by a user, the manual adjustment element being located at the end of the body opposite the head.

6. A handheld power tool as claimed in any one of the preceding claims, wherein the head is pivotable through a range not beyond 90 degrees, not beyond a range of 120 degrees, not beyond a range of 150 degrees, or not beyond a range of 180 degrees.

7. A handheld power tool as claimed in any one of the preceding claims, further comprising a locking mechanism for releasably locking the pivotable head at a position relative to the body so as to prevent or inhibit undesirable pivoting of the head.

8. A handheld power tool as claimed in any one of the preceding claims, wherein the power tool is battery operated

9. A handheld power tool as claimed in claim 8, wherein the body includes a cavity for accepting one or more batteries or battery packs.

10. A handheld power tool as claimed in any one of the preceding claims, wherein the power tool is mains powered.

11. A handheld power tool as claimed in any one of the preceding claims, wherein the tool portion is adapted to releasably engage a screwdriver bit.

12. A handheld power tool as claimed in any one of claims 1 to 10, wherein the tool portion includes a chuck for releasably engaging a tool bit.

13. A handheld power tool substantially as hereinbefore described with reference to the accompanying drawings.