GB2460944A

GB2460944A - Protective hood for a power tool

Info

Publication number: GB2460944A
Application number: GB0910310A
Authority: GB
Inventors: Joerg Maute; Florian Esenwein; Manfred Lutz
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2008-06-17
Filing date: 2009-06-15
Publication date: 2009-12-23
Anticipated expiration: 2029-06-15
Also published as: US20090311953A1; GB2460944B; DE102008002468A1; CN101607391A; GB0910310D0

Abstract

A protective hood 6 which is to be fastened on a clamping neck 2 of a power tool such as an angle grinder comprises a fastening part or clamping strap 8, which is tightened by an actuating element 11, such as a screw, and an adjustable latching component 9, which is movable between latching and unlatching positions by the actuating element 11. The clamping neck 2 of the power tool may include indentations 10 to cooperate with a latching element 13 of the latching component 9. The latching component 9 may pivot between the latching and unlatching positions and may be formed on the clamping strap 8 with the latching element 13 projecting through the clamping strap 8. The latching component 9 may include a spring biasing it to the unlatched position. The clamping neck 2 may be formed with a circumferential slot (22 fig 6) and means such as a pin may be provided which projects into the slot (22 fig 6) and locates the clamping strap 8 axially on the clamping neck 2.

Description

Description Title

Power tool, in particular hand-held power tool The invention relates to a power tool, in particular a hand-held power tool, such as, for example, an angle grinder, according to Claim 1, and, for a hand-held power tool, a protective hood according to Claim 5.

Prior art

A hand-held electric power tool having a disc-shaped rotating tool over which extends a protective hood held on a clamping neck of the power tool with the aid of a clamping strap is known from DE 102 59 520 Al. A tool holding fixture for the rotational mounting of the tool is situated in the clamping neck. The clamping strap for fixing the protective hood on the clamping neck is tightened with the aid of a screw.

In addition, a latching component is articulatedly mounted on the outside of the clamping strap, which latching component projects with a latching element through an opening in the wall of the clamping strap and engages in toothing on the outer lateral surface of the clamping neck.

In this way, positive locking can be produced between the clamping strap and the clamping neck in the circumferential direction and prevents rotation of the clamping strap and protective hood on the clamping neck. As a result, the safety particularly in the event of a breakage of the tool is increased.

The latching element is arranged on a latching handle which is articulatedly mounted on the outside of the clamping strap and is manually pivotable between the latching position, in which the latching element engages with the toothing on the clamping neck, and an unlatching position.

Disclosure of the invention

The object on which the invention is based is to simplify a power tool, in particular a hand-held power tool, having a protective hood held on a clamping neck via a fastening device, in its handling and its construction while ensuring high functional reliability, and also to provide a protective hood suitable in particular as equipment for such a power tool, but also as a conversion or retrofitting part of power tools.

This object is achieved according to the invention with regard to the power tool having the features of Claim 1 and with regard to the protective hood having the features of Claim 5.

In the case of the power tool according to the invention, a common adjustment of the fastening part and the latching part is achieved by the common actuation of the fastening part and the latching component via an actuating element, and hence in one operation both the fastening part is brought into its fastening position and the latching component is brought into its latching position with respect to the clamping neck.

The actuating element thus has a dual function: on the one hand the fastening part is tightened and on the other hand the latching component is moved into the latching position.

Separate actuation of the latching component can thus be dispensed with. It is sufficient to bring the fastening part into the clamping position via the actuating element, while at the same time the latching component is moved into the latching position via the actuating element. This results in considerable simplification of the handling, which is achieved with constructionally simple means. With the tightening of the fastening part, the latter exerts a radial clamping force, via which the protective hood is firmly clamped on the clamping neck. Additional securing is achieved via the latching component engaging with the clamping neck, this additional securing being formed in particular as positive locking which acts in the circumferential direction and/or in the axial direction, for which purpose the clamping neck has, on its lateral surface, toothing which extends in the circumferential direction and in which the latching element engages in the latching position.

Furthermore, a circumferential slot may be provided on the clamping neck, which slot preferably extends over the entire circumference of the clamping neck. In combination with the toothing, this leads to a design in which the tooth-shaped indentations forming the toothing extend in the axial direction, starting from the circumferential slot.

The circumferential slot has the function of securing the protective hood on the clamping neck in the axial direction in a positive-locking manner. This is preferably effected via the latching element of the latching component, which thus has, in addition to the securing in the circumferential direction, also the function of securing in the axial direction. The latching element may be moved within the circumferential slot on adjustment of the protective hood in the circumferential direction. In principle, however, it is also possible for a further component, for example a pin or peg on the protective hood or the clamping strap, to engage in the circumferential slot.

According to an alternative embodiment, the circumferential slot is formed separately from the toothing by, for example, arranging the circumferential slot in an axially offset manner on the lateral surface of the clamping neck with respect to the toothing. In this embodiment, the securing in the axial direction is effected via a separate component, such as the pin or peg already mentioned above.

The protective hood according to the invention is preferably used in hand-held power tools, in particular in electrically operated hand-held power tools having a rotating, preferably disc-shaped, tool, for example an angle grinder, where the protective hood, which extends around the rotationally mounted tool of the power tool, is to be fastened to a clamping neck of the power tool via the fastening device. The fastening device of the protective hood has a fastening part, which is to be tightened via an actuating element, and a latching component, which is to be moved between a latching position with the clamping neck and an unlatching position.

In the case of the protective hood according to the invention and its fastening device, it is provided that the actuating element acts upon both the fastening part and the latching component, whereby with the fastening of the fastening part with the aid of the actuating element at the same time the latching component is to be brought into the latching position. Despite the dual function of the fastening device, a simple construction of the protective hood is obtained, which hood, as a functional unit with its fastening device, also forms a. replacement and retrofitting part which can be used -at least without major adaptation being required -also in exchange for protective hoods of other design in many power tools.

The fastening part is preferably in the form of a clamping strap which is laid around the clamping neck and is tightened via the actuating element. In principle, however, differently constructed fastening parts via which the protective hood is to be secured on a component of the power tool are also possible.

According to a preferred embodiment, the latching component is held exclusively on the fastening part, so that the fastening part and the latching component form a common module which is to be adjusted by the actuating element.

The actuating element may also be held directly on the fastening part, in particular when embodied as a screw, which, in the case of an embodiment as a clamping strap, in a known manner connects two radially bent-up end sections of the clamping strap. The free end side of the screw preferably constitutes the contact surface, with which the screw lies in contact with the latching component and moves the latter from the unlatching position into the latching position.

In principle, however, it is also possible to hold the latching component on another tool component, for example in particular directly on the protective hood or on a housing component of the power tool. Furthermore, it is possible for the actuating element not to be embodied as a screw, but for example as a toggle-type fastener, the toggle-type fastener acting upon the latching component during the fastening operation. Optionally, the actuating element is held not on the clamping strap, but another component, such as, for example, the protective hood or a housing part.

There are various possibilities for the movement of the latching component on transfer from the unlatching position into the latching position. Preferably, the latching component executes a pivoting or rotating movement here, although a translatory adjusting movement or a combined translatory-rotary adjusting movement is also possible in context of the invention.

In the case of an articulated mounting, the point of application or contact between the actuating element and the latching component lies at a distance from the axis of articulation of the latching component, thus ensuring that a resultant moment about the axis of articulation takes effect, via which moment the latching component is moved into the latching position.

Furthermore, it may be expedient to assign a spring element to the latching component, which spring element is advantageously supported on the same component as the latching component, in particular on the clamping strap, and acts upon the latching component with a force in the direction of the unlatching position. This ensures that the latching component is automatically moved back into the unlatching position again by the action of the spring element, as soon as the actuating element is moved into the release position, in which the clamping strap is also in the loosened state. Thus, with a single adjusting movement of the actuating element, on the one hand the clamping strap is tightened and at the same time the latching component is moved into the latching position, while on the other hand on an opposite movement of the actuating element the clamping strap is loosened and at the same time the latching component is moved into the unlatching position.

It may, however, also be expedient to provide, additionally or alternatively to the spring element, a mechanical coupling between the actuating element and the latching component, via which coupling the latching component on a releasing movement of the actuating element is drawn by the latter into the unlatching position. The coupling may be effected, for example, via a driving element.

In the case of an articulated mounting, the rotary joint of the latching component may occupy different positions in relation to the latching element, which comes to bear against the clamping neck, and the actuating element, provided that a distance is ensured both between the rotary joint and latching element and also between the rotary joint and point of contact between the actuating element and latching component. One possibility is, for example, an arrangement in which the latching element lies between the position of contact with the actuating element and the rotary joint. However, a positioning of the rotary joint between the latching element and the actuating element is also possible.

Further advantages and expedient embodiments can be found in the further claims, the description of the figures, and the drawings, in which: Fig. 1 shows a section through a hand-held electric power tool in the form of an angle grinder, in the region of the tool, over which there extends a protective hood held on a clamping neck of the power tool, Fig. 2 shows the clamping neck and protective hood in a section perpendicularly to the axis of the tool, Fig. 3 shows the fastening device of the protective hood, via which the protective hood is secured to the clamping neck, having a clamping strap, a screw which tightens the clamping strap, and a latching component which is to be moved into a latching position by the screw, Fig. 4a shows a further fastening device, in which the latching component has a modified embodiment, Fig. 4b shows a spring element which acts upon the latching component according to Fig. 4a with a force, Fig. 5 shows yet another fastening device in an alternative embodiment, Fig. 6 shows a bearing flange having a clamping neck, in which a bearing for the tool is accommodated, there being formed in the outer lateral surface of the clamping neck a circumferential slot with toothing, by which the latching component is to be brought into the latching position, Fig. 7 shows a bearing flange similar to Fig. 6, but with a separate, axially offset embodiment of the circumferential slot, and toothing extending over the circumference.

In the figures, identical components are provided with the same reference symbols.

The hand-held power tool 1 illustrated in Fig. 1 is embodied as an angle or cut-off grinder which has in a clamping neck 2 a bearing 3 for the rotationally mounted accommodation of a drive spindle 4, which is the carrier of a tool 5 embodied as a grinding or cut-off disc. Extending partly around the tool 5 is a protective hood 6, which has an integrally formed-on, cylindrical collar 7, which is slipped onto the outside of the clamping neck 2. The collar 7 is firmly clamped on the clamping neck 2 via a clamping strap 8 of a fastening device, an additional latching component 9 for securing in the circumferential direction and/or in the axial direction being provided and the latching component 9 projecting through an opening in the collar 7 and into a tooth-shaped indentation 10 formed in the lateral surface of the clamping neck 2.

As can be seen in Fig. 2, the clamping strap 8 has, in a manner known per se, at its end sides radially bent-up end sections 8a, 8b, in each of which is formed an opening, through which is passed a screw, which forms an actuating element 11. The screw is secured to the clamping strap via a nut, so that as the screw 11 is screwed in, the clamping strap 8 is tightened and laid around the clamping neck 2 with increasing clamping force acting in the radial direction.

The free end side 12 of the screw 11 lies in contact with a section of the latching component 9, which component is to *be brought into a latching position with the clamping neck 2. As can be seen in Fig. 2 in conjunction with Fig. 3, the latching component 9 is in the form of a lever, there being formed in one piece with the latching component 9 a latching element 13 which extends, with respect to the base body of the latching component 9 extending approximately in the circumferential direction, radially inwards in the direction of the outer lateral surface of the clamping neck 2. An opening 14, through which the latching element 13 projects, is formed in the clamping strap 8.

On the side facing away from the screw 11, the base body of the latching component 9 is mounted rotatably or pivotably via a rotary joint 15 and at the same time held on the clamping strap 8. The rotary joint 15 is situated on the outside of the clamping strap 8 and is connected to the clamping strap. In addition, a spring element may be provided, which acts upon the latching component 9 with a force in the direction of the unlatching position, in which the latching element 13 of the latching component 9 is at least partly lifted out of the opening 14. The rotary joint enables the latching component 9 to perform a rotary movement about an axis which lies parallel to the axis of rotation of the tool.

On the side facing the actuating element 11, the base body of the latching component 9 has a contact section 9a which is bent over in a hook shape and lies in contact with the free end side 12 of the actuating element 11 embodied as a screw. The hook-shaped contact section 9a is formed such that as the screw 11 is increasingly screwed in, the base body of the latching component 9 and hence also the latching element 13 is moved into the latching position by the contact between the free end side 12 and the section 9a. The latching position is illustrated both in Fig. 2 and in Fig. 3. If a spring element is provided, which acts upon the latching component 9 with a force in the direction of the unlatching position, it is possible to use, for example, a leg spring which is placed around the rotary joint 15.

In the exemplary embodiment according to Fig. 2 and Fig. 3, the rotary joint 15 is situated on the side facing away from the actuating element 11. The latching element 13 on the latching component 9 lies between the rotary joint 15 and the point of contact between the free end side 12 of the actuating element 11 and the hook-shaped contact section 9a on the latching component 9.

Instead of a separately formed spring element, it is also possible to produce the latching component 9 from a resilient material, for example spring steel, and to prestress it in a way that the latching component 9 in the mounted position is moved by its internal stress into the unlatching position. This has the advantage that a spring element embodied as a separate component can be dispensed with.

The latching component 9 has a limit stop 23, which is arranged, starting from the rotary joint 15, on the side of the rotary joint facing away from the actuating element 11.

The limit stop 23 has the function of limiting the pivoting-up movement of the latching component 9 about the axis of rotation of the rotary joint 15. For this purpose, the limit stop 23, which is advantageously formed in one piece with the latching component, projects at an angle away from the outside of the clamping strap 8, the angle with respect to the outside of the clamping strap defining the maximum pivoting-up angle of the latching component 9.

In the maximum pivoted-up position, the limit stop 23 bears against the outside of the clamping strap 8.

In the exemplary embodiment according to Fig. 4a, the latching component 9 is illustrated in an alternative embodiment. The rotary joint 15 of the latching component 9 lies between the latching element 13 and the point of contact on the free end side 12 of the actuating element 11. The base body of the latching component 9 is of angular construction, the free end side, which faces away from the rotary joint 15, at the same time forming the latching element 13 which is passed through the opening 14 in the clamping strap 8. The free end side 12 of the screw 11 lies close to the angular region in the base body in contact with the latching component 9.

Illustrated in Fig. 4b in a component drawing is a spring element 16, embodied as a leg spring, which can be placed around the rotary joint 15 in Fig. 4a and in the mounted position acts upon the latching component 9 with a force in the direction of the unlatching position.

Illustrated in Fig. 5 is a further exemplary embodiment, in which it is possible in principle to dispense with a separate spring element which acts upon the latching component 9 in the direction of the unlatching position.

The movement of the latching component 9 both from the unlatching position into the latching position and in the opposite direction, i.e. from the latching position into the unlatching position, is effected by the adjusting movement of the actuating element 11 embodied as a screw.

For this purpose, the screw 11 is connected in the region of its end side to the base body of the latching component 9 via a driving element 17. Arranged on the side opposite the driving element 17 is a spring element 18, which is in the form of a compression spring and presses the latching component 9 axially against the driving element 17. Thus, on the one hand it is ensured that, on a screwing-in movement of the actuating element 11, the latching component 9 is moved into the latching position, and on the other hand, play or a flexibility in the components can be compensated for with the aid of the spring element 18 and the axial displacing movement of the latching component 9 on the actuating element 11. The latching element 13, which in the latching position engages with the toothing on the lateral surface of the clamping neck, is formed in one piece with the base body of the latching component 9 as in the previous exemplary embodiment.

The possibility of axial displacement of the latching component 9 along the axis of the screw 11 offers the further advantage that, with regard to the illustration according to Fig. 5, on relative rotation of the clamping strap 8 in the clockwise direction, self-locking occurs and as a result the positive locking between the latching component and toothing on the clamping neck increases. By contrast, in the opposite direction, the latching component can perform a relative movement owing to the free travel on the actuating element 11, as a result of which a limited play is achieved.

Illustrated in Fig. 6 is a bearing flange 19, comprising a base plate 20 and the clamping neck 2 which is embodied in one piece with the base plate and in which the bearing 3 for the drive spindle 4 is accommodated. Formed in the outer lateral surface of the clamping neck 2 is toothing 21, consisting of a plurality of tooth-shaped indentations which extend in the axial direction and are distributed over the circumference, and which are assigned to the latching element of the latching component, the latching element in the latching position projecting into a tooth-shaped indentation in each case. As a result, positive locking is achieved both in the circumferential direction and in the axial direction.

The tooth-shaped indentations each extend axially, starting from a circumferential slot 22 extending over the entire circumference of the clamping neck 2. The latching element of the latching component can be displaced along the circumferential slot 22. Optionally, however, a component formed separately from the latching element, such as, for example, a pin or the like projects into the circumferential slot and thereby secures the clamping strap and the protective hood on the clamping neck in the axial direction.

In the exemplary embodiment according to Fig. 7, which likewise shows a bearing flange 19 with a base plate 20 and clamping neck 2, the toothing 21 is formed separately from the circumferential slot 22. The toothing 21 lies adjacent to the upper side of the base plate 20, whereas the circumferential slot 22 lies adjacent to the end side of the clamping neck 2. In this embodiment, it is absolutely essential for a component formed separately from the latching component to project into the circumferential slot 22, for example a pin or the like.

Claims

Claims 1. Power tool, in particular hand-held power tool, such as, for example, angle grinder, having a protective hood (6), which is to be fastened to a clamping neck (2) via a fastening part (8), a latching component (9), which can be latched against the clamping neck (2), and a common actuating element (11) for the fastening element (8) and the latching component (9), via which the fastening part (8) and the latching component (9) can be adjusted with respect to the clamping neck (2).
2. Power tool according to Claim 1, characterised in that the clamping neck (2) of the power tool (1) has toothing (21) which extends in the circumferential direction and in which a latching element (13) of the latching component (9) engages in the latching position.
3. Power tool according to Claim 1 or 2, characterised in that a circumferential slot (22) is provided on the clamping neck (2)
4. Power tool according to Claim 3, characterised in that, starting from the circumferential slot (22) on the clamping neck (2), tooth-shaped indentations extending in the axial direction are formed in the lateral surface of the clamping neck (2)
5. Protective hood for a power tool (1), in particular for a hand-held power tool, such as, for example, an angle grinder, which protective hood is to be fastened to a clamping neck (2) of the power tool (1) via a fastening device having a fastening part (8), which is to be adjusted via an actuating element (11), and a latching component (9), which can be moved into a latching position with respect to the clamping neck (2), in particular according to one of the preceding claims, characterised in that the actuating element (11) acts upon both the fastening part (8) and the latching component (9), whereby with the fastening of the fastening part (8) via the actuating element (11) at the same time the latching component (9) is to be brought into the latching position.
6. Protective hood according to Claim 5, characterised in that the fastening part (8) of the fastening device is a clamping strap (8) which is to be tightened via the actuating element (11).
7. Protective hood according to Claim 5 or 6, characterised in that the latching component (9) is held on the fastening part (8).
8. Protective hood according to one of Claims 5 to 7, characterised in that the latching component (9) is articulatedly mounted and is pivotable between the latching position and the unlatching position.
9. Protective hood according to Claim 8, characterised in that the actuating element (11) acts upon the latching component (9) at a distance from the axis of articulation of the latter.
10. Protective hood according to Claim 8 or 9, characterised in that the axis of articulation of the latching component (9) lies between a latching element (13), acting upon the fastening part (8), of the latching component (9) and the point of contact for the actuating element (11)
11. Protective hood according to Claim 8 or 9, characterised in that the latching element (9) acting upon the fastening part (8) lies between the point of contact for the actuating element (11) and the axis of articulation of the latching component (9)
12. Protective hood according to one of Claims 5 to 11, characterised in that the latching component (9) is arranged on the outside of the fastening part (8) and in that in the latching position the latching element (13) of the latching component (9) projects through the fastening part (8).
13. Protective hood according to one of Claims 5 to 12, characterised in that the actuating element (11) is held translationally movably on the fastening part (8) and is embodied in particular as a screw.
14. Protective hood according to one of Claims 5 to 13, characterised in that the latching component (9) is acted upon with a force in the direction of its unlatching position via a spring element (16)
15. Protective hood according to Claim 14, characterised in that the spring element is formed in one piece with the latching component (9)
16. Protective hood according to one of Claims 5 to 15, characterised in that the actuating element (11) bears loosely against the latching component (9).
17. Protective hood according to one of Claims 5 to 15, characterised in that the actuating element (11) is connected to the latching component (9), in particular via a driving element (17)
18. Protective hood according to one of Claims 5 to 17, characterised in that the latching component (9) in the latching position brings about positive locking in the circumferential direction.
19. A protective hood for a power tool substantially as herein described with reference to the accompanying drawings.
20. A power tool substantially as herein described with reference to the accompanying drawings.