DE102008041720B4 - Hand tool with brush motor - Google Patents

Abstract

Hand tool (10) with a motor housing (16), in particular an elongated one serving as a handle, the interior of the motor housing (16) being accessible via a service opening (26) in the motor housing 10 (16) which can be closed with a lid (22 to 2210), characterized in that the cover (22) on its outer side, remote from its outer edge, carries a recess (29) for the engagement of a tool (58) for opening the cover (22).

Description

State of the art

The present invention is based on a hand tool according to the preamble of claim 1.

Electric handheld power tools are usually used today by universal electric motors, i.e. driven by collector or brush motors. For commutation, current is transferred from the power cable via brushes to the collector of the motor, which is rotating during operation. The brushes are fixed in the motor housing using a brush holder, which in most cases is made of plastic. The brush holder has a shaft that guides the brush axially. It is equipped with a spring that presses the brush towards the collector. The brush wears at its contact point on the collector due to friction and moves axially towards the collector under the action of the spring in accordance with the loss of length due to wear. This allows the current flow between the collector and brush to be maintained. In most cases, the brushes have to be replaced several times over the life of the electric hand tool.

In order to enable easy replacement of the brush, known motor housings have service openings through which the carbon brush can be accessed directly. To ensure electrical safety, the service openings can be closed in a watertight and dustproof manner using covers that can be attached to the motor housing with screws or similar elements. The outer surfaces of these covers are usually flush with the contour of the machine housing.

After loosening the fastening screw, the cover that closes the service opening can be removed from the motor housing. For this purpose, this has a recess or radial recess on its outer edge for engaging and levering out the cover with a screwdriver blade or similar tool. These depressions form a geometric discontinuity in the edge of the cover and can impair electrical safety if the seal to the service opening is damaged when the cover is opened. There, electrically conductive dust and moisture can penetrate into the interior of the device and form an electrical line connection, which places the outside of the device under the operating voltage of the power tool.

From the prior art such as DE 28 49 871 A1 a lid for closing an opening of a machine housing is known. Furthermore, the JP H07-266 260 A. also such a lid.

The DE 44 30 161 A1 , the DE 199 59 920 A1 and the JP 2003-191 180 A. also disclose a lid for closing an opening in a machine housing.

The object of this invention is to improve a cover of an engine housing.

Advantages of the invention

The invention with the features of claim 1 has the advantage that the new cover ensures the electrical safety of the handheld power tool and is comfortable, easy to open, so that service work can be carried out more quickly.

The fact that the motor housing according to the invention is only changed in such a way that the demolding, e.g. Removal of the motor housing from the injection mold can still take place at a 90 ° angle, the motor housing can be produced without increasing the cost.

Because the cover according to the invention has a recess which is arranged at a distance from its outer edge or outside the interface to the machine housing, it can be opened using a suitable tool without impairing the electrical safety.

Characterized in that the lid according to the invention opens automatically during / after loosening a captive fastening screw, the carbon brush is quickly accessible without any additional operating effort.

The fact that at least one circumferential seal is arranged between the cover according to the invention and the service opening improves the electrical safety and mechanical damping of the hand tool. In addition, the cover screw is secured in position by means of elastic prestressing by means of the seal and rattling noises between the motor housing and cover are excluded.

Because the cover according to the invention is provided with rubber or similar damping elements in the contact area to the motor housing, the cover in the handle area of the device housing serves as an anti-vibration cushion, which reduces the transmissible vibrations and thus the stress for the operator of the hand-held power tool and thus the ease of use and increased operator safety.

Characterized in that the lid according to the invention after loosening the fastening screw and opening the lid captively on Machine housing sits, the ease of use when changing brushes is significantly improved.

Because the cover according to the invention forms a locking means for a further removable part, in particular a covering cap, of the machine housing, the interior of the motor housing is particularly easily accessible for inspections and service work.

The fact that the lid according to the invention serves as a hold-down device for the brush holder means that a separate hold-down device and its fastening screw that was previously necessary can be dispensed with.

list of figures

• 1 einen erfindungsgemäßen Winkelschleifer mit Serviceöffnung und Deckel
• 2 einen Ausschnitt des Motorgehäuses des Winkelschleifers nach 1
• 3 einen Längsschnitt des Motorgehäuses im Bereich des Deckels nach 2
• 4 einen weiteren Längsschnitt des Motorgehäuses im Bereich des Deckels
• 5 einen weiteren Längsschnitt des Motorgehäuses mit einer Variante des Deckels
• 6 einen Längsschnitt nach 5 mit einer weiteren Variante des Deckels
• 7 und 8 einen Längsschnitt mit einer Unter-Variante des Deckels in zwei Montageschritten
• 9 einen Längsschnitt nach 5 mit einem mit O-Ring abgedichteten Deckel
• 10 einen Längsschnitt nach 5 mit einem mit elastischen Dichtungen schwingungsgedämpften Deckel
• 11 und 12 einen Längsschnitt eines Deckels mit Scharnierverbindung zum Motorgehäuse
• 13 einen Längsschnitt eines Motorgehäuses mit 2 Deckeln auf entgegen gesetzten Seiten, die als Haltemittel für ein weiteres Gehäuseteil dienen 14 eine Unteransicht eines Deckels mit Stützelement
• 15 eine Draufsicht auf die Serviceöffnung des geöffneten Motorgehäuses mit einer Ansicht des mit dem Deckel korrespondierenden Bürstenhalters und
• 16 eine Seitenansicht des Motorgehäuses mit Deckel und Bürstenhalter nach 15.

The invention is explained in more detail below on the basis of an exemplary embodiment with the associated drawing. Show it

• 1 an angle grinder according to the invention with service opening and cover
• 2 a section of the motor housing of the angle grinder 1
• 3 a longitudinal section of the motor housing in the area of the cover 2
• 4 another longitudinal section of the motor housing in the area of the cover
• 5 a further longitudinal section of the motor housing with a variant of the cover
• 6 a longitudinal section 5 with another variant of the lid
• 7 and 8th a longitudinal section with a sub-variant of the lid in two assembly steps
• 9 a longitudinal section 5 with a lid sealed with an O-ring
• 10 a longitudinal section 5 with a vibration-damped cover with elastic seals
• 11 and 12 a longitudinal section of a cover with a hinge connection to the motor housing
• 13 a longitudinal section of a motor housing with 2 lids on opposite sides, which serve as holding means for another housing part 14 a bottom view of a lid with support element
• 15 a plan view of the service opening of the open motor housing with a view of the brush holder corresponding to the cover and
• 16 a side view of the motor housing with cover and brush holder after 15 ,

embodiment

One in 1 Handheld machine tool shown spatially is as an angle grinder 10 designed and has a gear housing at the front, as seen on the left 12 , which is made of metal. From this comes down, parallel to the vertical axis 20 of the angle grinder 10 an unillustrated output shaft for receiving an unillustrated grinding wheel by a protective hood 14 is embraced. At the back is the gearbox 12 a motor housing 16 flange-mounted in a pot design, which receives an electric collector motor or brush motor, commonly referred to as hand-held power tools, from the rear a cable 18 to power the motor.

The motor housing serving as a handle 16 has a lid in the middle on its top 22 with a cover screw 24 contour-flush on the motor housing 16 is attached and there is a service opening 26 closes dust-tight. Diametrically opposite is - not visible - on the underside of the motor housing 16 a second service opening 26 with an associated lid 22 arranged so that the power supply to the motor is secured as usual via two brushes offset by 180 °. The lid 22 has three decorative grooves running across the longitudinal axis of the angle grinder 28 , of which that of the cover screw 24 next decorative groove 28 at the bottom a central, about 6 mm deep, 6 mm wide slit-like depression 28 for engaging a screwdriver blade or the like, for example a fingernail, a paper clip or a coin - for prying open the lid 22 , The prerequisite is that the cover screw 24 is solved.

In 2 is a section of the motor housing 16 of the angle grinder 10 with the lid 22 shown. Here is the lid 22 with the three decorative grooves running transversely to the longitudinal axis 28 and the slot-like depression 29 clearly visible. The deepening 29 lies within the outer contour of the motor housing 16 and is robustly sealed towards the inside of the housing.
Next are a side switch button 15 for operating the on / off switch and side ventilation slots 17 for sucking in engine cooling air and three grip areas 19 of the motor housing 16 referred to, the lid 22 itself and the area in front of and behind the motor housing 16 are at least partially provided with a surface layer which improves grip and reduces vibrations.

In 3 is a longitudinal section of the motor housing 16 in the area of the cover 2
shown. Here is the lid 22 recognizable in longitudinal section, its decorative grooves 28 who have favourited Deepening 29 and the screw hole 23 on its outside and
at the front edge the L-shaped end face for reaching behind the hinge-like
neighboring
Housing wall. The lid bears on its underside 22 one protruding downwards
hollow cylindrical area of the screw hole 23 for reaching over a screw dome 30 of
motor housing 16 in which the cover screw 24 to fix the lid 22 on the motor housing 16 is screwable. The lid 22 covers the service opening with its outer edge 26 seals and secures the underlying electrical motor parts, such as brush holders 54 and brush holder screw 55 against contact and against ingress of dust and moisture. Next is a screwdriver 58 shown to engage in the recess 28 is suitable, whereby after inserting the screwdriver blade the lid 22 in the direction of the movement arrow 60 can be opened.

In 4 is another longitudinal section of the motor housing 16 in the area of the lid 221 sketch, with its L-shaped cranked lid edge 25 Is recognizable, the hinge-like engagement in a housing groove 34 in the edge of the service opening 26 or the adjacent housing wall. Next is a concentric screw dome 30 embracing, looking up at the lid 221 supporting prestressed compression spring 32 shown when or after loosening the cover screw 24 the lid 221 swings outwards or upwards. Aids for lifting the lid or corresponding recesses are not necessary.

5 shows a further longitudinal section of the motor housing 16 in the area of the lid 222 , its L-shaped lid rim 25 for hinge-like gripping behind the housing groove 34 the adjacent housing wall and a spring tongue 321 that are down on a ramp 36 pre-tensioned and after loosening the cover screw 24 the lid 22 swings outwards or upwards. The ramp 36 is in the motor housing 16 integrated.

In 6 is different from 5 a spring tongue 322 designed as a separate part made of steel or similar resilient material and on the lid 223 assembled. With 5 Matching details will not be listed again.

In 7 and 8th is a longitudinal section after 5 with a sub-variant of the lid 224 shown. Its L-shaped lid rim 25 forms a pre-tensioned spring tongue which, when pressed into the housing groove 34 the lid 224 is stretched and the lid 224 tries to keep open. When loosening the cover screw 24 the spring tongue pretensioned during assembly bends back into its starting position and the cover 224 opens up.

In 9 is a longitudinal section after 5 with one with o-ring 38 sealed lid 225 shown, the circumferential seal as an inserted rubber ring in the form of the lid edge 25 , the service opening 26 or the interface contour or as a sealing edge molded directly onto the motor housing and / or onto the brush cover.

10 shows a longitudinal section 5 with a vibration-damped cover with elastic seals 226 that as a domed pillow with decorative grooves 28 is designed and its damping to the motor housing 16 and to the screw dome 30 by means of a suitable, optionally on the motor housing 16 or lid 225 its ring-shaped damping means assigned to its outer edge 40 is effected. This can be done directly in the two-component plastic injection molding on the lid 225 and / or motor housing 16 to be appropriate. Here is the damping agent 40 be designed in such a way that one section is more compressed than the other and that this results in the cover 22 with loosening the cover screw 24 swiveling opens.

In the 11 and 12 is a longitudinal section of a lid 227 . 228 with hinge connection to the motor housing 16 shown so that the lid cannot be lost, can be opened on the machine housing 16 is held, either as a rotary hinge 44 , the cover when the machine is first assembled 227 is clipped in or as a film hinge 46 where the lid 228 directly to the machine housing 161 is injected.

13 shows a longitudinal section of the motor housing 16 with two lids arranged on opposite sides 229 that as a holding means for another as a cap 161 designed housing part serve that after opening the lid 229 easily from the rest of the case 16 is solvable. The brush cover 229 form the lock for the cover cap 161 , for which no separate screw connection or the like is therefore required.
So that's the inside of the motor housing 16 in the area of its cover cap 161 who z. B. the power line 18 with spout 181 , the electrical switch etc. more easily accessible, e.g. for repair work and for exchange.
To remove the cover cap 116 just need both lids 229 after loosening the cover screws 23 be opened so that the positive connection between the lids 229 and cover cap 116 is solved. To do this, the lids have 229 a hook-like locking element 48 for reaching behind a suitable, circumferential groove 49 the cover cap 116 , When opening the lid 22 then becomes the cover cap 161 released and can be removed. The lids 229 can be pivotally mounted in a hinge, a latch or the like.

14 shows the bottom view of a lid 2210 with stamp-like support element 50 that as a hold-down of a brush holder 54 ( 16 ) serves. This will make for the brush holder 54 no separate fixing element, such as. B. requires its own screw connection. To do this, the brush holder 54 a counter stamp 52 , on which the support element 50 supported.
If a separate screw connection of the brush holder is nevertheless arranged, form a support element 50 and counter stamp 52 an emergency stop if the brush holder screw comes loose from the screw hole in the event of overload and / or extremely high temperatures, for example if the brush holder vibrates excessively or the motor housing melts out 16 , A passage of the overheated brush holder through the motor housing 16 or the lid 2210 This prevents it because the counter-punch sits on an area of the brush holder that is less exposed to temperature and thus on the lid with only a low maximum temperature 2210 or the support element 50 can act.

15 shows a top view of the service opening 26 of the open engine case 16 with the one with the lid 2210 ( 16 ) via the counter stamp 52 corresponding brush holder 54 , This is without a brush holder screw 55 ( 3 ) with the lid 2210 fixable.

16 shows a side view of the motor housing 16 with the mounted lid 2210 with support element 50 that is on the counter stamp 52 of the brush holder 54 to 15 supported.

The exemplary embodiments of the invention can be combined with one another in a relatively varied manner, for example the support geometry of the cover 2210 for the brush holder 54 with a captive brush cover or the recess for an aid to open the cover with the damping.
Furthermore, as an aid to opening the lid, square, hexagonal or
Instead of the hand-held power tool described as an angle grinder, a hand drill, scraper, orbital sander, jigsaw etc. can also be equipped with a motor housing designed as a handle with the brush holder according to the invention, with or without a service opening and cover.

Claims (17)

Hand tool (10) with a motor housing (16), in particular an elongated one serving as a handle, the interior of the motor housing (16) being accessible via a service opening (26) in the motor housing 10 (16) which can be closed with a lid (22 to 2210), characterized in that the cover (22) on its outside, remote from its outer edge, carries a recess (29) for the engagement of a tool (58) for opening the cover (22). Hand machine tool after Claim 1 , characterized in that the recess (29) is used to engage a screwdriver blade (58), a hexagon wrench, a coin or the like and is adapted to this. Hand machine tool after Claim 2 , characterized in that several recesses (29) - in particular in the middle and / or sitting between its center and its outer edge - are arranged suitably for different tools. Hand machine tool (10) after Claim 1 With an elongated motor housing (16), in particular serving as a handle, which receives an electric collector motor (50), the cover (22) being fixable to the motor housing (16), in particular by means of a screw connection, characterized in that between the cover ( 22) and the motor housing (16) are arranged spring means (32, 321, 322, 323) which can be pretensioned when the cover (22) is fixed and which attempt to open the cover (22). Hand machine tool after Claim 1 or 2 , characterized in that the cover (22) has a plurality of circumferential seals to the motor housing (16). Hand machine tool after Claim 5 , characterized in that the cover (22) carries rubber or similar damping means (40) in the contact area with the motor housing (16). Hand tool according to one of the preceding claims, characterized in that the cover (22) is held captively, in particular by means of a film hinge (46), on the motor housing (16). Hand tool according to one of the preceding claims, characterized in that the cover (22) forms a lock for a further part (161) of the motor housing (16) and releases the lock when the cover (22) is opened. Hand tool according to one of the preceding claims, characterized in that the cover (22) serves as a hold-down of a brush holder (54), in particular a carbon brush holder. Hand tool according to one of the preceding claims, characterized in that the cover (22) carries holding means on its inner surface for holding a spare part, in particular a spare carbon brush. Hand tool according to one of the preceding claims, characterized in that the cover (22) can be fixed to the motor housing (16) by means of a screw connection, the cover (22) carrying on its underside a hollow cylindrical region of the screw hole (23) which projects downwards, the Screw hole (23) for gripping a screw dome (30) of the mother housing (16) is used, the cover screw (24) for fixing the cover (22) on the motor housing (16) can be screwed. Hand tool according to one of the preceding claims, characterized in that the cover (22) is arranged in the handle region (19) and serves as an anti-vibration cushion. Hand tool according to one of the preceding claims, characterized in that the cover (2210) has a stamp-like support element (50) which serves as a hold-down of a / the brush holder (54). Hand machine tool according to one of the Claims 9 to 13 , characterized in that the brush holder (54) has a counter-stamp (52) on which the support element (50) is supported. Hand machine tool after Claim 14 , characterized in that the support element (50) and the counter-punch (52) form an emergency stop if a brush holder screw (55) comes loose from the screw hole in the event of overload and / or extremely high temperatures. Hand machine tool according to one of the Claims 14 to 15 , characterized in that the counter-stamp sits on a region of the brush holder which is subjected to less temperature and thus acts on the cover (2210) or the support element (50) with only a low maximum temperature. Hand machine tool according to one of the Claims 15 to 16 , characterized in that the brush holder (54) can be fixed without the brush holder screw (55) with the cover (2210).

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