Electric handheld power tool

Abstract

The invention proposes an electric handheld power tool (1) having a drive motor for driving a drive spindle (2), the drive spindle (2) being mounted by a first bearing means (3) and by a second bearing means (4), and having a catch mechanism, which comprises a catch mechanism receiving part (5) which can be brought into engagement with a latching disc (6) which is connected to the drive spindle (2). The catch mechanism receiving part (5) forms the second bearing means (4).

Description

[0001] R.415389

[0002] - 1 -

[0003] Description

[0004] title

[0005] Electric hand tool machine

[0006] The invention relates to an electric hand-held power tool according to the preamble of claim 1.

[0007] State of the art

[0008] Electric hand tools, such as cordless impact drills, are known to use an electric motor as their drive unit. This motor drives a switchable ratchet mechanism to generate the impact function. The ratchet mechanism comprises a housing-mounted ratchet assembly with a circumferential, sinusoidal wave profile on its end face. This wave profile interacts with a circumferential ratchet disc, which is connected to the drive spindle of the hand tool, to generate the impact function. The drive spindle carries a tool holder and is driven by the motor shaft of the electric drive motor. Since forces, such as contact pressure, are transmitted to the tool via the drive spindle, it is supported by two bearings in the gearbox housing or the machine housing. The increased overall length of the drive train resulting from this known drive spindle mounting can sometimes be problematic.

[0009] Disclosure of the invention

[0010] The invention is based on the objective of improving the compactness and precision of an electric hand-held power tool equipped with a ratchet mechanism by means of simple design measures.

[0011] This problem is solved according to the invention by the features of claim 1. The dependent claims specify advantageous embodiments. R.415389

[0012] - 2 -

[0013] The electric hand-held power tool according to the invention has a drive motor for driving a drive spindle, the drive spindle being supported by a first bearing and a second bearing. The electric hand-held power tool further has a ratchet mechanism comprising a ratchet mechanism receiver which engages with a ratchet disk connected to the drive spindle. The ratchet mechanism receiver forms the second bearing.

[0014] Because the indexing mechanism mounting part acts as the second bearing element, no additional bearing element is required, thus reducing the overall length of the electric power tool's drive train. Simultaneously, the first bearing element and the indexing mechanism mounting part, which serves as the second bearing element, provide sufficient support for the drive spindle, ensuring adequate drive train precision. In other words, increased precision is achieved while maintaining the same overall length. As described above, a reduction in the number of components required, i.e., the need for a separate bearing, is particularly advantageous, resulting in simplified assembly and cost reduction.

[0015] In order to provide a more compact and at the same time precise drive train of the electric hand tool, which can also have improved stability, the first bearing means is in an advantageous embodiment at least partially, preferably completely, accommodated within the ratchet mechanism receiving part.

[0016] For the purposes of the invention, a drive train can be understood to comprise at least one drive spindle together with its corresponding bearing. The drive train may optionally include a detent mechanism.

[0017] According to a further advantageous embodiment, the indexing mechanism mounting part can be arranged on the drive spindle essentially without gaps. In particular, stable bearing of the drive spindle can be achieved without negatively affecting the precision characteristics of the drive train of the electric hand-held power tool. R.415389

[0018] - 3 -

[0019] To further improve the stability of the drive train and to enable reliable, high-precision operation, the first bearing element and the detent disc can be connected to the drive spindle. In particular, the detent disc and the first bearing element can be rigidly connected to the drive spindle. It is also possible for only the detent disc to be rigidly connected to the drive spindle. Preferably, the detent disc is axially fixed on the drive spindle. Preferably, the detent disc and the first bearing element are axially and rotationally fixed on the drive spindle. The detent disc and the first bearing element are preferably press-fitted to the drive spindle. It is also possible for the detent disc and / or the first bearing element to be integrally formed with the drive spindle.In other words, the ratchet disc and the drive spindle can be formed as a single piece. Alternatively or additionally, the first bearing element and the drive spindle can be formed as a single piece.

[0020] In one embodiment, the first bearing element can be held in the ratchet mechanism's receiving part, particularly axially, by means of a retaining element. A retaining element can reliably hold or fix a first bearing element, especially one designed as a fixed bearing, axially within the housing, thereby enabling reliable operation of the electric hand tool.

[0021] In a further advantageous embodiment, the first bearing can be axially supported by a spring element that can be supported in the ratchet mechanism mounting part. This advantageously enables reliable operation of the ratchet or impact function of the electric hand tool, while simultaneously providing an electric hand tool with a more compact yet precise drive train. The spring element also facilitates easy switching from the impact drilling function and prevents unintentional operation of the impact mechanism.

[0022] To ensure sufficient and reliable dissipation of the frictional heat that can arise during operation of the indexing mechanism, i.e., during frictional contact between the indexing mechanism mounting part and the indexing disc, the indexing mechanism mounting part, which is preferably fixed to the housing in the direction of rotation, is in contact with a heat dissipation element located in the housing or in a Ge- R.415389

[0023] - 4 - is arranged in the drive housing of the hand-held power tool. The heat dissipation element is preferably designed as an independent component that is fixed to the housing but is not part of the housing. This allows the heat dissipation element to be optimized for its heat-dissipating function. The heat dissipation element is particularly large and made of a material with high thermal conductivity. Through contact between the heat dissipation element and the chuck mounting part, heat is initially transferred to the heat dissipation element by thermal conduction, within which the heat spreads according to the same principle. Advantageously, the heat dissipation element extends to the tool holder, in particular to a gap between the end face of the housing and the tool holder, so that, in the case of a rotating drill chuck, the airflow generated contributes to cooling the heat dissipation element.

[0024] In order to provide a compact electric hand tool with improved precision using simple design measures, it can be advantageously provided that the second bearing means has a greater axial distance to an end face of a housing of the electric hand tool than the first bearing means, wherein the first bearing means is designed as a fixed bearing, in particular as a rolling bearing and / or that the second bearing means is designed as a floating bearing, in particular as a sliding bearing.

[0025] In an advantageous embodiment, the ratchet mechanism receiving part can be cup-shaped. This allows for the integration of, in particular, the first bearing element, and thus enables a compact design of the ratchet mechanism or the drive train. Furthermore, heat dissipation towards the end face of the housing can occur via a cylindrical or substantially cylindrical cup wall, which can advantageously increase the service life.

[0026] In one embodiment, the indexing mechanism mounting part and / or the indexing disc may be made at least partially of a metallic material, in particular a sintered metal. Advantageously, a sufficiently stable yet easy-to-manufacture indexing mechanism mounting part can be provided. This applies accordingly to the indexing disc. Alternatively, it may be provided that the indexing mechanism mounting part and / or the indexing disc are made of a metallic material, in particular a sintered metal. R.415389

[0027] - 5 - disc is / are manufactured by means of metal powder injection molding. It is also possible that the indexing mechanism mounting part and / or the indexing disc is / are manufactured by means of a flow forming process.

[0028] Several advantages can be achieved with the design according to the invention. A reduced overall length of the drive train of the electric hand tool can be achieved with minimal design effort. At the same time, the precision of the drive train can be maintained despite the shortened drive train. Thus, the precision of the drive train can be increased for the same overall length. Furthermore, a reduction in the number of components is possible, which also simplifies assembly, maintenance, and repair. By additionally using a heat dissipation element, effective heat dissipation of the heat generated during idle operation can also be achieved, which can have a beneficial effect on extending the service life of the electric hand tool.

[0029] Further advantages and practical designs can be found in the additional requirements, the figure description, and the drawings. These show:

[0030] Fig. 1 shows an electric hand-held power tool in a highly simplified schematic representation.

[0031] Fig. 2 shows a section of the electric hand-held power tool in a sectional view.

[0032] Fig. 3 shows an exploded view of a section of the electric hand-held power tool.

[0033] In the figures, identical components are labelled with the same reference symbols.

[0034] The hand-held power tool 1 shown in Figure 1 has a housing 13 and an electric drive motor 12 arranged therein.

[0035] According to one embodiment, the electric hand tool 1 can be mechanically and electrically connected to a battery pack (not shown) for mains-independent power supply. The power tool is exemplified as a cordless drill / driver. However, it should be noted that R.415389

[0036] - 6 - the present invention is not limited to cordless drills, but can rather be used in various, in particular battery-operated, power tools, e.g. a cordless screwdriver, a cordless impact drill, etc.

[0037] The housing 13 contains an electric drive motor 12, powered by a battery pack 17, and a gearbox 14. The drive motor 12 can be operated via a manual switch (not shown), i.e., switched on and off, and can be any type of motor, e.g., an electronically commutated motor or a DC motor. Preferably, the drive motor 12 is electronically controllable such that both reversing operation and setting a desired rotational speed are possible.

[0038] The drive motor 12 is connected to a drive spindle 2 via the gearbox 14, which is arranged in an optional gearbox housing 14a. The gearbox 14 is in particular designed as a planetary gearbox, preferably as a two-stage planetary gearbox.

[0039] The housing 13 or the gearbox housing 14a are preferably made of plastic, in particular of a thermoplastic material such as polyamide (PA), especially PA6, PA66 or the like. Such plastics exhibit particularly good wear resistance.

[0040] The drive spindle 2 carries a drill chuck 15 with a tool holder. Specifically, the drive spindle 2 is threaded 18 so that the drill chuck 15 can be detachably attached. In impact drilling mode, the drive spindle 2 is mounted to be axially displaceable relative to the gearbox housing 14a.

[0041] The drive spindle 2 is rotatably mounted in the housing 13 via a bearing arrangement. The bearing arrangement consists of a first bearing element 3 and a second bearing element 4. The first bearing element 3 is spaced apart from the second bearing element 4.

[0042] The first bearing 3 is arranged at least partially in the area of ​​the end face 13a of the housing 13 and can therefore subsequently also be referred to as werk- R.415389

[0043] - 7 - The bearing means on the tool mounting side can be referred to or understood as the bearing means on the gearbox side. The second bearing 4 can also be referred to or understood as the bearing means on the gearbox side.

[0044] The electric hand-held power tool 1 further comprises a ratchet mechanism 11, which can also be referred to or understood as a striking mechanism. The ratchet mechanism 11, or striking mechanism, is designed to implement a striking function, and the ratchet mechanism 11 includes a ratchet mechanism mounting part 5 and an annular ratchet disk 6. The annular ratchet disk 6 is connected to the drive spindle 5 by means of an interference fit.

[0045] The indexing disc 6 has a circumferentially circumferential, sawtooth-like wave profile on an end face facing the gearbox, which can be operatively connected to the indexing mechanism mounting part 5 when approached axially. In other words, the indexing disc 6 has teeth on 16 that can be engaged with teeth on the indexing mechanism mounting part 5. In the impact drilling position, contact between the indexing mechanism mounting part 5 and the indexing disc 6 occurs when the tool is pressed in a tool holder against a workpiece to be machined (not shown).

[0046] The electric hand tool 1 thus has a drive motor 12 for driving a drive spindle 2, the drive spindle 2 being supported by a first bearing 3 and a second bearing 4. The electric hand tool 1 also has a ratchet mechanism 11, which includes a ratchet mechanism mounting part 5 that engages with a ratchet disk 6 connected to the drive spindle 2. The ratchet mechanism mounting part 5 forms the second bearing 4.

[0047] The first bearing element 3 is accommodated within the grid mounting part 5. In other words, the first bearing element is enclosed by the grid mounting part 5. Consequently, the first bearing element 3 encloses the component that contains the second bearing element 4.

[0048] The second bearing element 4 is preferably designed as a plain bearing and has a radial air gap of between 0.001 mm and 0.03 mm, particularly preferably between 0.003 mm and 0.02 mm, to the drive spindle 2. R.415389

[0049] - 8 -

[0050] The second bearing 4, or the ratchet mechanism mounting part 5, which is cup-shaped, is arranged between the gearbox housing 14a and a heat dissipation part 9, in particular in a supporting manner. The ratchet mechanism mounting part 5 is thus in contact with a heat dissipation part 9 arranged in the housing 13 of the hand-held power tool 1, thereby enabling corresponding heat dissipation from the ratchet mechanism mounting part 5, made of sintered metal, to the metal heat dissipation part 9.

[0051] The indexing mechanism mounting part 5 further encloses a spring element 7, which is arranged to provide support within the indexing mechanism mounting part 5. The indexing mechanism mounting part 5 also encloses the indexing disk 6 and the first bearing element 3, with a retaining element 8 arranged between the indexing disk 6 and the first bearing element (see also Figure 3). The spring element 7 bears on one side against a base area 17 of the indexing mechanism mounting part 5 and moves the retaining element 8, and thus the first bearing element 3, which is designed as a ball bearing, against the heat dissipation element 9.

[0052] The retaining element 8 has an annular base body 8a with three legs 8b arranged thereon. Preferably, the legs 8b are arranged at equal intervals on the base body 8a. The base body 8a and legs 8b are preferably formed in one piece. The retaining element can also have fewer than three legs in a manner not shown in detail. It is also possible for the retaining element to have more than three legs.

[0053] The legs 8b of the retaining part 8 are bent in a direction that points towards guide slots 5a formed in the ratchet mechanism receiving part 5, and can be inserted into these slots. In this case, the ratchet mechanism receiving part 5 has three guide slots 5a, corresponding to the number of legs 8b on the retaining part 8.

[0054] The electric hand-held power tool 1, in the illustrated embodiment, further comprises a switching element 10, which can also be referred to as a selector ring, and by means of which a percussion drilling operation can be selected or set. The switching element 10 is specifically designed to switch between a percussion drilling operation and a drilling operation without a percussion function. To select a percussion drilling operation or to switch between a drilling operation without a percussion function and a drilling operation with R.415389

[0055] - 9 -

[0056] In the impact function, the holding element 8 is released axially by means of the switching element 10, so that the first bearing element 3 is movable axially. The guide slots 5a thus act as tangential guides for the holding element 8. Figure 3 shows a section of the electric hand-held power tool 1, which can be considered and designated as the drive train 19. The drive train 19 has at least the drive spindle 2 and a bearing system comprising the first bearing element 3 and the second bearing element 4, wherein the second bearing element 4 is formed by the ratchet mechanism receiving element 5.

Claims

R.415389 - 10 - Claims 1. Electric hand-held power tool (1) with a drive motor (12) for driving a drive spindle (2), wherein the drive spindle (2) is supported by a first bearing means (3) and by a second bearing means (4), and with a ratchet mechanism (11) comprising a ratchet mechanism receiving part (5) which is to be brought into engagement with a ratchet disk (6) which is connected to the drive spindle (2), characterized in that the ratchet mechanism receiving part (5) forms the second bearing means (4).

2. Electric hand tool (1) according to claim 1 , characterized in that the first bearing means (3) is at least partially, preferably completely, received within the ratchet mechanism receiving part (5).

3. Electric hand tool (1) according to at least one of the preceding claims, characterized in that the ratchet mechanism receiving part (5) is arranged substantially without gaps on the drive spindle (2).

4. Electric hand tool (1) according to at least one of the preceding claims, characterized in that the first bearing means (3) and the ratchet disc (6) are connected to the drive spindle (2).

5. Electric hand tool (1) according to at least one of the preceding claims, characterized in that the first bearing means (3) is held in the ratchet mechanism receiving part (5) by means of a retaining part (8).

6. Electric hand tool (1) according to at least one of the preceding claims, characterized in that the first bearing means (3) is axially supported by a spring element (7) which can be supported in the ratchet mechanism receiving part (5).

7. Electric hand tool (1) according to at least one of the preceding claims, characterized in that the ratchet mechanism receiving part (5) is in contact with a heat dissipation part (9) arranged in the housing (13) of the hand tool (1). R.415389 - 11 - 8. Electric hand tool (1) according to at least one of the preceding claims, characterized in that the second bearing means (4) has a greater axial distance to an end face (13a) of a housing (13) of the electric hand tool (1) than the first bearing means (3), wherein the first bearing means (3) is designed as a fixed bearing, in particular as a rolling bearing and / or that the second bearing means (4) is designed as a floating bearing, in particular as a sliding bearing.

9. Electric hand tool (1) according to at least one of the preceding claims, characterized in that the ratchet mechanism receiving part (5) is cup-shaped.

10. Electric hand tool (1) according to at least one of the preceding claims, characterized in that the ratchet mechanism receiving part (5) and / or the ratchet disc (6) is / are made at least partially of a metallic material, in particular of a sintered metal.

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