Swash plate bearing for a power tool, and power tool

Abstract

The invention relates to a swash plate bearing (1) for a power tool (2) with a striking mechanism (3), comprising - an inner ring (4), - an outer ring (5), - bearing balls (6), via which the outer ring (5) is movably mounted on the inner ring (4), and - a cage (7), in which the bearing balls (6) are guided. According to the invention, in order to seal a bearing gap (8) between the inner ring (4) and the outer ring (5), a respective sealing disc (9) is provided on both sides of the bearing gap (8), the sealing disc (i) being secured to the cage (7) or formed by the cage (7) and extending over the outer ring (5) in the radial direction at least in some regions or (ii) being secured to the outer ring (5) or formed by the outer ring (5) and extending over the cage (7) in the radial direction at least in some regions. The invention also relates to a power tool (2) with a striking mechanism (3) and a swash plate bearing (1) according to the invention.

Description

[0001] 2023P00006EP

[0002] Hilti Aktiengesellschaft

[0003] Principality of Liechtenstein

[0004] Swashplate bearing for a power tool, power tool

[0005] DESCRIPTION

[0006] The invention relates to a swashplate bearing for a power tool according to the preamble of claim 1. Furthermore, the invention relates to a power tool with a swashplate bearing according to the invention.

[0007] The invention is primarily applicable to handheld power tools, in particular rotary hammers and / or demolition hammers. These tools have an impact mechanism for applying the necessary impact energy to the tool.

[0008] State of the art

[0009] Power tools with a percussion mechanism driven by an electric motor via a drive shaft are well-known. The rotary motion of the drive shaft must be converted into a translational motion of a working cylinder within the percussion mechanism. The drive shaft and the working cylinder can be connected to a swashplate bearing via a coupling device.

[0010] An example of such a coupling or transmission device for a striking device is shown in DE 102008 040 765 A1. The transmission device has a wobble bearing with an inner ring and an outer ring. The inner ring is arranged on an intermediate shaft. The outer ring is movably mounted on the inner ring. On opposite sides of its outer circumference, the outer ring has a wobble leg, which is oriented tangentially with respect to the outer ring. At their free ends, the wobble legs each have a bearing bore in which a bearing pin extending perpendicular to the wobble legs is received. This pin is connected to a piston of a piston assembly via a pin-like transmission element. With the aid of the transmission device, a rotational movement of the intermediate shaft can be converted into an axial movement of the piston.

[0011] Swashplate bearings of the type described above form a bearing gap between the inner and outer rings, in which bearing balls are held and guided by a cage. If particles, such as dust particles, penetrate the bearing gap, they increase wear in the area of ​​the contact surfaces subjected to rolling friction on the inner ring, the outer ring, and the bearing balls. To prevent the ingress of particles into the bearing gap, a seal can be provided. However, a problem arises because the available space for the seal is limited, and the distance between the outer and inner rings changes when the outer ring moves. Therefore, the use of standard seals is generally not possible.

[0012] The present invention is therefore concerned with providing a sealing concept for a swashplate bearing that enables effective sealing of a bearing gap against particles and is easy and cost-effective to implement.

[0013] To solve the problem, a swashplate bearing with the features of claim 1 is proposed. Advantageous embodiments of the invention are described in the dependent claims. Furthermore, a power tool with a swashplate bearing according to the invention is described.

[0014] Disclosure of the invention

[0015] The swashplate bearing proposed for a power tool with a percussion mechanism comprises an inner ring, an outer ring, bearing balls by which the outer ring is movably mounted on the inner ring, and a cage in which the bearing balls are guided.

[0016] According to the invention, a sealing disc is arranged on both sides of the bearing gap between the inner ring and the outer ring to seal the bearing gap, which

[0017] (i) is attached to the cage or is formed by the cage and extends in a radial direction at least partially over the outer ring or

[0018] (ii) is attached to the outer ring or is formed by the outer ring and extends at least partially in a radial direction over the cage.

[0019] The sealing washers positioned on both sides of the bearing gap counteract the entry of particles into the bearing gap. This means that fewer particles reach the contact area between the bearing balls and the inner and outer rings, which is subject to rolling friction. Consequently, wear in this area is reduced.

[0020] The sealing washers are arranged either on the cage or on the outer ring. The sealing washers can be attached to the cage or outer ring as separate elements, or they can be formed by the cage or outer ring through a corresponding design. The one-piece design has the advantage of eliminating assembly steps and thus simplifying assembly. The separate manufacturing and subsequent attachment of the sealing washers to the cage or outer ring has the advantage that existing swashplate bearings can be retrofitted to a swashplate bearing according to the invention.

[0021] The seal is achieved by positioning the sealing washers either on the cage or the outer ring, extending radially over the other component so that the bearing gap in this area is covered by the sealing washers. The sealing washers do not make contact with the other component, thus creating a non-contact seal. This has the advantage of not being subject to friction and therefore being less prone to wear. Furthermore, the lack of friction results in less heat being generated in the bearing. Because the sealing washers extend radially over at least part of the outer ring or the cage, a gap forms between the sealing washers and the outer ring or cage, respectively. This gap acts as a labyrinth seal. The sealing effect is therefore achieved, among other things, by the fact that the gap between the sealing washers and the outer ring or cage...The gap remaining in the cage increases the path that particles must travel to reach the bearing gap. Therefore, the radial extent of the sealing washers is preferably chosen to be as large as possible.

[0022] In a further development of the invention, it is therefore proposed that, when the sealing discs are arranged on the cage, the sealing discs are guided completely over the outer ring in the radial direction, and preferably the sealing discs also encompass the outer circumference of the outer ring. This increases the gap between the sealing discs and the outer ring and also introduces at least one change in direction. The sealing effect is thereby further improved.

[0023] The sealing washers, regardless of whether they are located on the cage or the outer ring, are preferably spaced apart from the inner ring. This distance ensures that no friction occurs between the sealing washers and the inner ring, and that the seal is truly contactless. Here, too, the distance is chosen to be as small as possible to prevent particles from entering the bearing gap. Furthermore, the distance of the sealing washers from the inner ring ensures freedom of movement for the cage or outer ring that incorporates the sealing washers.

[0024] According to a preferred embodiment of the invention, the cage is multi-part, in particular two-part, and each sealing washer is attached to or formed by a cage part. The multi-part design of the cage facilitates assembly, as the parts can be individually inserted into the bearing gap. This is particularly advantageous when the geometry of the sealing washers is selected such that, in the final installation position, they encompass the outer ring or extend behind it. Furthermore, it is proposed that the cage parts be connected via a press-fit, plug-in, snap-fit, or latching connection. The necessary connection of the cage parts can thus be achieved directly during insertion into the bearing gap, further simplifying assembly.

[0025] Advantageously, the cage and / or the sealing washers are made of plastic. As plastic parts, the cage and / or the sealing washers can be manufactured particularly cost-effectively, for example by injection molding.

[0026] Alternatively, it is proposed that the sealing washers be made of a metallic material. This is particularly advantageous when the sealing washers are arranged on the outer ring, which is preferably also made of a metallic material. The sealing washers can then be easily welded to the outer ring if manufactured separately, resulting in a very robust connection. Manufacturing the sealing washers from a metallic material also allows for the sealing washers to be produced as a single piece together with the outer ring. For example, the outer ring can be provided on both sides of its inner circumference with a flange extending in the axial direction, which is bent over after the bearing is mounted, so that the flange then extends in the radial direction. The terms "radial" and "axial" refer to the outer ring and its circular shape, respectively.

[0027] Furthermore, a power tool with an impact mechanism, in particular a pneumatic impact mechanism, is proposed. The proposed power tool has a swashplate bearing according to the invention, wherein preferably the inner ring of the swashplate bearing is arranged on a drive shaft and rigidly connected to it. The inner ring therefore rotates with the drive shaft. The outer ring, which is supported on the inner ring by the bearing balls, performs a wobbling motion.

[0028] To convert the rotation of the drive shaft into a translational motion, a pin is preferably arranged on the outer circumference of the swashplate bearing. The end of this pin, facing away from the outer ring, is received in a rotatably mounted bearing bolt oriented perpendicular to the pin. The bearing bolt is preferably rotatably mounted in a drive cylinder of the impact mechanism via bearing bores. The drive cylinder has a longitudinal axis running parallel to the axis of rotation of the drive shaft at a distance from this axis. In this way, the rotational motion of the drive shaft is converted into a translational motion of the drive cylinder parallel to the axis of rotation of the drive shaft.

[0029] Furthermore, preferably the drive cylinder is designed in a fork-shaped manner at its end and has two arms, in each of which a bearing bore is formed for the rotatable mounting of the bearing bolt.

[0030] Preferred embodiments of the invention are described in more detail below with reference to the accompanying drawings. These show:

[0031] Fig. 1 shows a perspective view of a first preferred embodiment of a swashplate bearing according to the invention for a power tool with impact mechanism,

[0032] Fig. 2 shows a longitudinal section through the swashplate bearing of Figure 1 ,

[0033] Fig. 3 is an exploded view of the swashplate bearing of Figure 1 ,

[0034] Fig. 4 is an exploded view of the cage parts of the cage of the swashplate bearing of Figure 1 ,

[0035] Fig. 5 shows a perspective view of another preferred embodiment of a swashplate bearing according to the invention a) before the installation of the sealing discs and b) after the installation of the sealing discs and

[0036] Fig. 6 shows a longitudinal section through a power tool with a percussion mechanism and a wobble plate bearing. Detailed description of the drawings.

[0037] Figures 1 and 2 show a swashplate bearing 1 according to the invention for a power tool 2 with an impact mechanism 3, for example a pneumatic impact mechanism 3 analogous to Figure 6. The illustrated swashplate bearing 1 has an inner ring 4, an outer ring 5, bearing balls 6, and a cage 7. The outer ring 5 is movably mounted on the inner ring 4 via the bearing balls 6. The bearing balls 6 are guided by the cage 7. A sealing washer 9 is arranged on both sides of the cage 7 to seal a bearing gap 8.

[0038] As can be seen particularly in Figure 2, the sealing discs 9 arranged on the cage 7 are guided radially over the outer ring 5 and angled at their ends so that they encompass the outer ring 5. At the same time, the sealing discs 9 maintain a distance from the outer ring 5, so that a narrow, multiply angled gap is formed. This forms a labyrinth seal that prevents particles from entering the bearing gap 8.

[0039] To facilitate the assembly of the swashplate bearing 1 shown in Figures 1 and 2, the cage 7 is designed in multiple parts, for example, in two parts as shown in Figure 3 or in four parts as shown in Figure 4. In the two-part version (see Figure 3), the cage 7 is divided or halved in the middle, so that two essentially identical but mirrored cage parts 7.1, 7.2 are formed. These can be inserted into the bearing from either side and then connected, for example, by means of a snap-fit ​​connection. The sealing washer 9 connected to the respective cage part 7.1, 7.2 can be placed around the outer ring 5. In the four-part version (see Figure 4), the two cage parts 7.1, 7.2 are first assembled, and then the separately manufactured sealing washers 9 are connected to the cage parts 7.1, 7.2.

[0040] In an alternative design, the assembly sequence differs. It may be provided that the sealing washers 9 are first connected or joined to the cage parts 7.1, 7.2, and that the cage parts 7.1, 7.2 are then mounted in a subsequent step. The connection can be adhesive, welded, pressed, plugged, snap-fit, or latched. In this case, the sealing washers 9 form further cage parts 7.3, 7.4.

[0041] Another preferred embodiment of a swashplate bearing 1 according to the invention can be seen in Figures 5a) and 5b). Figure 5a) shows the bearing before the sealing discs 9 are mounted, and Figure 5b) shows the bearing after the sealing discs 9 have been mounted. In this embodiment, the sealing discs 9 are arranged on the outer ring 5 and are firmly connected to it, for example, by welding. The connection of the sealing discs 9 to the outer ring 5 takes place in the region of its end faces 20. The subsequent mounting of the sealing discs 9 has the advantage that the swashplate bearing 1 can first be mounted as usual, and the sealing discs 9 can then be attached. These only contact the outer ring 5, so that a non-contact seal of the bearing gap 8 is created via a narrow gap remaining between the sealing discs 9 and the cage 7, which acts like a labyrinth seal.

[0042] Figure 6 shows a power tool 2 with a percussion mechanism 3, into which a swashplate bearing 1 according to the invention can be integrated. The percussion mechanism 3 of the illustrated power tool 2 has a drive cylinder 14, which is operatively connected to a percussion piston 17 via an air spring 16. This piston, in turn, acts on a striker 18. Not shown is a tool clamped in the power tool 2, which is moved back and forth by the percussion mechanism 3 during operation of the power tool 2. The power tool 2 is driven by an electric motor (not shown) with a motor shaft 19, which is operatively connected to a drive shaft 10. The drive shaft 10 can therefore also be an intermediate shaft. The inner ring 4 of a swashplate bearing 1 is arranged on the drive shaft 10, so that it rotates with the drive shaft 10.The outer ring 5, which is mounted on the inner ring 4 via the bearing balls 6, performs a wobbling motion. This motion is transmitted to the drive cylinder 14 of the striking mechanism 3 via a pin 11 connected to the outer ring 5, the other end of which is received in a bearing bolt 12. For this purpose, the bearing bolt 12 is rotatably mounted in bearing bores 13 of a fork-shaped end of the drive cylinder 14, which forms two arms 15.

[0043] Reference symbol list

[0044] 1 Swashplate bearing

[0045] 2 power tools

[0046] 3 percussion instruments

[0047] 4 inner ring

[0048] 5 outer ring

[0049] 6 bearing balls

[0050] 7 cage

[0051] 7.1 Cage part

[0052] 7.2 Cage section

[0053] 7.3 Cage section

[0054] 7.4 Cage part

[0055] 8 bearing gap

[0056] 9 Sealing washer

[0057] 10 Drive shaft

[0058] 11 pen

[0059] 12 bearing bolts

[0060] 13 bearing bore

[0061] 14 drive cylinders

[0062] 15 Arm

[0063] 16 air spring

[0064] 17 pistons

[0065] 18 Döpper

[0066] 19 Motor shaft

[0067] 20 Front surface

Claims

REQUIREMENTS 1. Swashplate bearing (1) for a power tool (2) with a percussion mechanism (3), comprising an inner ring (4), an outer ring (5), Bearing balls (6) on which the outer ring (5) is movably mounted on the inner ring (4), and a cage (7) in which the bearing balls (6) are guided, characterized in that a sealing disc (9) is arranged on both sides of the bearing gap (8) to seal a bearing gap (8) between the inner ring (4) and the outer ring (5), which (i) is attached to the cage (7) or is formed by the cage (7) and extends in a radial direction at least partially over the outer ring (5) or (ii) is attached to the outer ring (5) or is formed by the outer ring (5) and extends at least partially in a radial direction over the cage (7).

2. Swashplate bearing according to claim 1, characterized in that the sealing discs (9) are spaced apart from the inner ring (4).

3. Swashplate bearing (1) according to claim 1 or 2, characterized in that the cage (7) is multi-part, in particular two-part, and each sealing disc (9) is attached to a cage part (7.1, 7.2) or is formed by a cage part (7.1, 7.2).

4. Swashplate bearing (1) according to claim 3, characterized in that the cage parts (7.1, 7.2) are connected via a press, plug, latch or snap connection.

5. Swashplate bearing (1) according to one of the preceding claims, characterized in that the cage (7) and / or the sealing discs (9) is / are made of plastic.

6. Swashplate bearing (1) according to one of claims 1 to 4, characterized in that the sealing discs (9) are made of a metallic material.

7. Power tool (2) with a striking mechanism (3), in particular a pneumatic striking mechanism (3), comprising a swashplate bearing (1) according to one of the preceding claims, wherein preferably the inner ring (4) of the swashplate bearing (1) is arranged on a drive shaft (10) and is rigidly connected to it.

8. Power tool (2) according to claim 7, characterized in that a pin (11) is arranged on the outer circumferential side of the outer ring (5) of the swashplate bearing (1), which is received at its end facing away from the outer ring (5) in a bearing bolt (12) which is rotatably mounted perpendicular to the pin.

9. Power tool (2) according to claim 7 or 8, characterized in that the bearing pin (12) is rotatably mounted via bearing bores (13) in a drive cylinder (14) of the impact mechanism (3), wherein the drive cylinder (14) has a longitudinal axis extending at a distance parallel to an axis of rotation of the drive shaft (10).

10. Power tool (2) according to claim 9, characterized in that the drive cylinder (14) is designed in a fork shape at its end and has two arms (15) in each of which a bearing bore (13) is formed for rotatably supporting the bearing bolt (12).

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