WO2024132914A1

WO2024132914A1 - Chainsaw

Info

Publication number: WO2024132914A1
Application number: PCT/EP2023/086024
Authority: WO
Inventors: Endre Zador
Original assignee: Robert Bosch Gmbh
Priority date: 2022-12-20
Filing date: 2023-12-15
Publication date: 2024-06-27
Also published as: DE102022214012A1

Abstract

The invention relates to a chainsaw (2) comprising a motor (20) and a transmission (30), in particular a motor-transmission unit (10), and comprising a housing (3), wherein the motor (20) and the transmission (30) are at least partly arranged within the housing (3), and the transmission (30) has a planetary transmission (30), said planetary transmission (30) having at least one rotationally fixed ring gear (32), a sun gear (31), which can be driven by the motor (20), and at least one planetary gear (37), which is mounted on a planet carrier (34). According to the invention, a chain gear (41) for driving a saw chain (42) is integrally formed together with the planet carrier (34).

Description

Title

Chainsaw

The invention relates to a chainsaw, in particular an electric-driven chainsaw, for example a one-handed chainsaw, i.e. a chainsaw which is intended to be operated with at least one hand.

State of the art

Chain saws according to the preamble of claim 1 are already known from the prior art.

Disclosure of the invention

The invention relates to a chainsaw with the features of claim 1. Advantageous further developments emerge from the dependent claims.

One object of the invention may be to provide an improved hand-held power tool in the form of a chainsaw. This can be designed to be more compact than the chainsaws known in the prior art.

The invention is based on a chainsaw, with a motor and a transmission, in particular a motor-transmission unit, and a housing, wherein the motor and the transmission are at least partially arranged within the housing, wherein the transmission has a planetary gear, wherein the planetary gear has at least one non-rotatable ring gear and a sun gear that can be driven by the motor and at least one planet gear mounted on a planet carrier. It is proposed that a sprocket for driving a saw chain is formed integrally with the planet carrier

The chainsaw is preferably a one-handed chainsaw. The motor is preferably an electric motor. The chainsaw has in particular a motor-gear unit. The motor-gear unit can be arranged at least partially within the housing. The motor-gear unit has in particular an electric motor and a planetary gear. It can be provided that the planetary gear has a plurality of planetary gears mounted on the planet carrier, for example two, three or four planetary gears. An output element of the motor-gear unit, in particular a chain wheel for driving a saw chain, is formed integrally with the planet carrier. The planet carrier is mounted on the housing with a planet carrier bearing, in particular rotatably mounted. A non-rotatable ring gear can be understood in particular to mean that the ring gear cannot be displaced in the circumferential direction, but is axially displaceable and/or tiltable or wobbleable relative to or around the axis of rotation. This makes it possible, for example, to compensate for tolerances, enable setting movements and/or achieve low-force and low-friction bearing or rolling of the planets and/or the planet carrier.

Such an arrangement allows a compact design of the chainsaw. The ring gear can be provided to be stationary. This can mean in particular that the ring gear is axially immovable, i.e. cannot be axially displaced.

In one embodiment, the output element or the sprocket is loaded on one side when the handheld power tool or chainsaw is in operation. Such a one-sided load can be caused, for example, by a chain of a chainsaw, but alternative designs of a handheld power tool are also conceivable in which the output element is loaded on one side. In such a design, it can be provided in particular that the output element or the sprocket and the planet carrier are mounted exclusively with the planet carrier bearing, so that in particular no further bearing is provided for the planet carrier or the output element or sprocket. It is proposed that a central shaft is mounted on the housing with a first central shaft bearing. The sun gear is firmly connected to the central shaft. This connection can be designed in particular as a press fit or with another shaft-hub connection. The first central shaft bearing can be a plain bearing or a roller bearing, for example a ball bearing. The motor can be in particular an electric motor. A rotor of the electric motor can be firmly connected to the central shaft. This connection can be designed for example as a press fit, but also as a key connection or the like. A stator of the electric motor can at least partially, in particular completely, surround or enclose the rotor. The central shaft, which is simultaneously connected to the sun gear of the planetary gear, further supports the compact design of the handheld power tool or chainsaw.

It is proposed that the central shaft is mounted on the planet carrier with a second central shaft bearing. The second central shaft bearing can in particular be a roller bearing or a plain bearing, for example a ball bearing. This enables a stable structure. Alternatively, it can be provided that the central shaft is only mounted via the sun gear of the planetary gear and no separate second central shaft bearing is provided.

It is proposed that the second central shaft bearing is arranged at least partially, in particular completely, in an inner region of the planet carrier bearing. In particular, the planet carrier bearing can have an inner cylinder in which the planet carrier is at least partially arranged. The second central shaft bearing can be arranged partially and in particular completely within the inner cylinder of the planet carrier bearing. The second central shaft bearing can be arranged in an inner cylinder of the planet carrier.

It is proposed that the motor is an electric motor and that the rotor and the sun gear are arranged between the first central shaft bearing and the second central shaft bearing. This also enables a compact design of the hand-held power tool. In one embodiment, the rotor, the Fan element and the sun gear are arranged between the first central shaft bearing and the second central shaft bearing.

It is proposed that the planetary gear is mounted on the planet carrier by means of a needle bearing. This can increase the stability of the motor and gearbox and/or the gearbox and the sprocket, particularly when the output element is loaded on one side, preferably when the hand-held power tool is in operation.

It is proposed that the motor is an electric motor and that a fan element is arranged between the rotor and the sun gear and connected to the central shaft. The fan element can be connected to the central shaft in particular by means of a press fit. The fan element can in particular contribute to cooling the electric motor and thus increase the efficiency of the electric motor. The arrangement between the sun gear and the rotor can support the compact design of the hand-held power tool.

It is proposed that the fan element is arranged in a fan housing. An opening of the fan housing is connected to a housing opening of the housing. This can improve a ventilation effect.

It is proposed that the fan element is an impeller. This has a fastening element. The fastening element is attached to the central shaft, for example by means of a press fit. The impeller is attached to the fastening element. The fastening element can be molded or cast around the impeller. The impeller can comprise plastic or be made of plastic. The fastening element can have a metal centering ring or can be a metal centering ring.

A further housing opening can be provided which faces the same side as the housing opening and is suitable for ejecting sawdust. The housing openings are preferably offset from one another along the central axis. In particular, one or more of the housing openings are designed to direct exhaust air along an outer hand guard area of a hand guard. This ensures that sawdust is guided past the hand holding the power tool.

It is proposed that the ring gear has at least one radial projection, with which a rotation of the ring gear about a central axis can at least be restricted. The central axis can correspond to the central shaft and/or be a central axis of the electric motor. The radial projection is arranged in particular on the outside. More than one radial projection, for example two, three or four radial projections, can also be provided. The radial projection or projections can ensure that the ring gear is rotationally stable. It can be provided that, despite the projection, in particular an axial movement of the ring gear and/or a tilting movement of the ring gear and/or a wobbling movement of the ring gear along or about the central axis can be made possible.

It is proposed that the projection be arranged in a counter element of the housing. The counter element can be a form-fitting element. If necessary, a counter element can be provided for each radial projection. The counter element can be designed as a groove parallel to the central axis direction in the housing. Side walls of the groove prevent the projection from twisting about the central axis. The groove can, however, enable axial movement of the projection. The projection can thus be fixed in a rotationally fixed but not stationary manner. The counter element can in particular limit movement of the ring gear in the circumferential direction, although play in the axial direction can remain possible. This can compensate for tolerances, for example. The ring gear can tilt at least slightly relative to the central axis. A one-sided load on the output element or on the planet carrier and/or on the planets can be compensated. A low-jamming rolling of the gear, in particular the planet gears, can be made possible. In particular, the counter element can provide a rotationally fixed but not stationary support for the cantilever.

It is suggested that the chain or saw chain be guided around a chainring.

The central axis or the central shaft is essentially vertical right, in particular at an angle between 80 and 100 degrees, preferably between 89 and 91 degrees, to the chainring.

It is proposed that the first central shaft bearing is arranged in a central shaft bearing receptacle of the housing. The planet carrier bearing is arranged in a planet carrier bearing receptacle of the housing.

Embodiments of the invention are explained with reference to the following drawings. The schematic drawing shows:

Fig. 1 is a view of a hand-held power tool as a chainsaw;

Fig. 2 shows a cross-section through the hand tool;

Fig. 3 shows another cross-section through the hand tool;

Fig. 4 shows another cross-section through the hand tool;

Fig. 5 shows another cross-section through the hand tool; and

Fig. 6 shows another cross-section through the hand tool.

Fig. 1 shows a view of a handheld power tool 1: The handheld power tool 1 is designed as a chainsaw 2. The handheld power tool 1 comprises a housing 3. A motor 20 and a gear 30 are at least partially arranged in the housing 3, in particular as a motor-gear unit 10. Furthermore, Fig. 1 shows a power supply 8, in this case designed as a rechargeable battery, in particular a removable battery pack. Alternatively, it can also be provided to implement the power supply 8 by means of a power cable. Furthermore, the housing 3 of the handheld power tool 1 in particular has a hand guard 9. The handheld power tool 1 can be driven with the motor-gear unit 10. If the handheld power tool 1 is designed as a chainsaw 2 as shown in Fig. 1, a saw chain 42 in particular can be driven with the motor-gear unit 10. Fig. 2 shows a cross section through the handheld power tool 1 of Fig. 1. The motor-gear unit 10 has an electric motor 20 and a planetary gear 30. The electric motor 20 can be supplied with direct current or alternating current, for example, via the power supply 8 shown in Fig. 1. In particular, the electric motor 20 is an EC motor. In principle, however, another motor, for example a combustion or hydraulic motor or the like, could also drive the handheld power tool 1. The planetary gear 30 has at least one non-rotatable ring gear 32, a sun gear 31 that can be driven by the motor 20, and at least one planet gear 37 mounted on a planet carrier 34. An output element 40 of the transmission 20, in particular of the motor-transmission unit 30, is designed here as a chain wheel 41 for driving the saw chain 42. It is connected to the planet carrier 34 or is formed in one piece with the planet carrier 34. The planet carrier 34 is mounted on the housing 3 with a planet carrier bearing 35.

It can be provided that the ring gear 32 is stationary. This can mean in particular that the ring gear 32 is axially immovable, i.e. cannot be axially displaced. In particular, it can be provided that the ring gear 32 cannot be moved to the left or right in the embodiment of Fig. 2. In another embodiment, it can be provided that the ring gear 32 has axial play and movements to the left or right are possible at least to a small extent in the embodiment of Fig. 2.

It can be provided that the planetary gear 30 has a plurality of planet gears 37 mounted on the planet carrier 34, for example two, three or four planet gears 37. Here, three planet gears 37 are provided.

In one embodiment, the output element 40 is loaded on one side when the hand-held power tool 1 is in operation. Such a one-sided load can be caused in particular by the saw chain 42 of the chain saw 2, but alternative designs of a hand-held power tool 1 are also conceivable in which the output element 40 is loaded on one side. The output element 40 and the planet carrier 34 can be mounted exclusively with the planet carrier bearing 35, so that in particular no further bearing is provided for the planet carrier 34. A central shaft 11 with a first central shaft bearing 12 can be mounted on the housing 3. The sun gear 31 can be firmly connected to the central shaft 11. The first central shaft bearing 12 can be a plain bearing or a roller bearing, for example a first ball bearing 13. A rotor 21 of the electric motor 20 can be firmly connected to the central shaft 11. A stator 25 of the electric motor 20 can at least partially surround the rotor 21. The connection between the rotor 21 and the central shaft 11 can be designed, for example, by means of a press fit, but also as a key connection or the like. It can be provided that the stator 25 completely surrounds the rotor 21. In particular, the stator 25 can enclose the rotor 21. The connection between the sun gear 31 and the central shaft 11 can in particular be designed as a press fit or with another shaft-hub connection. The central shaft 11, which is simultaneously connected to the sun gear 31 of the planetary gear 30 and to the rotor 21 of the electric motor 20, allows a compact construction of the hand-held power tool 1 to be achieved.

The rotor 21 can comprise rotor magnets 22 and the stator 25 stator windings 26. Energizing the stator windings 26 can in particular result in a rotational movement of the rotor 21.

The central shaft 11 can be mounted on the planet carrier 34 with a second central shaft bearing 14. The second central shaft bearing 14 can in particular be a roller bearing or a plain bearing, for example a second ball bearing 15. This enables a stable structure. Alternatively, it can be provided that the central shaft 11 is only mounted via the sun gear 31 of the planetary gear 30 and no separate second central shaft bearing 14 is provided. This design is not shown in Fig. 2, but results if the second central shaft bearing 14 is omitted.

The second central shaft bearing 14 can be arranged at least partially in an inner region of the planet carrier bearing 35. In particular, the second central shaft bearing 14 can be arranged completely in an inner region of the planet carrier bearing 35. In particular, the planet carrier bearing 35 can have an inner cylinder in which the planet carrier 34 is at least partially The second central shaft bearing 14 can be arranged partially and in particular completely within the inner cylinder of the planet carrier bearing 34. In particular, it can be provided that a cutting plane through the hand-held power tool 1, which is perpendicular to the central shaft 11 (and is also perpendicular to the drawing plane of Fig. 2), cuts both the planet carrier bearing 35 and the second central shaft bearing 14. In such an arrangement, the second central shaft bearing 14 is arranged at least partially in an inner region of the planet carrier bearing 35.

The rotor 21 and the sun gear 31 can be arranged between the first central shaft bearing 12 and the second central shaft bearing 14. The planet gear 37 can be mounted on the planet carrier 34 by means of a needle bearing 38.

The first central shaft bearing 12 can be arranged in a central shaft bearing receptacle 4 of the housing 3. The planet carrier bearing 35 can be arranged in a planet carrier bearing receptacle 5 of the housing 3. A fan element 51 can be arranged between the rotor 21 and the sun gear 31 and connected to the central shaft 11. The fan element 51 can be connected to the central shaft 11 in particular by means of a press fit or by means of a key connection. The fan element 51 can in particular contribute to cooling the electric motor 20 and thus in particular increase the efficiency of the electric motor 20. The arrangement between the sun gear 31 and the rotor 21 can support the compact design of the motor-gear unit 10 and thus of the handheld power tool 1.

Fig. 3 shows a further cross section through the hand-held power tool 1 of Figs. 1 and 2 through the cutting plane designated A in Fig. 2. The fan element 51 can be arranged in a fan housing 54, wherein an opening 55 of the fan housing 54 is connected to a housing opening 6 of the housing 3. This can improve a ventilation effect.

The fan element 51 can have an impeller 52 and a fastening element 53. The fastening element 53 can be fastened to the central shaft 11. The fastening element 53 can be fastened to the central shaft 11, for example by means of a press fit or a key connection. The impeller 52 can be fastened to the fastening element 53. The fastening element 53 can be encapsulated or cast by the impeller 52. The fastening element 53 can have a metallic centering ring or can be a metallic centering ring. The impeller 52 can comprise plastic or be formed from plastic, in particular comprise a plastic composite material or be formed from it.

In Fig. 3, a further housing opening 56 is shown, which faces the same side as the housing opening 6 and is suitable for ejecting sawdust. The housing openings 6, 56 are preferably offset from one another along the central axis. In particular, one or more of the housing openings 6, 56 are designed to direct exhaust air along an outer hand guard area 57 of a hand guard 9. This makes it possible to direct sawdust past a hand holding the handheld power tool.

Fig. 4 shows a further cross section through the hand-held power tool 1 of Figs. 1 to 3 through the cutting plane designated B in Fig. 2. The ring gear 32 can have at least one radial projection 33, with which rotation of the ring gear 32 about a central axis can be at least limited, in particular prevented. The central axis can correspond to the central shaft 11, be arranged parallel to the central shaft 11 or be a central axis of the electric motor 20. The radial projection is arranged in particular on the outside. In particular, it has a rectangular basic shape. More than one radial projection 33, for example two, three, four or more radial projections 33, can also be provided. Here, three projections are provided. As a projection, as a casing of the projection or instead of the projection, in particular as a casing of the ring gear, an elastic connecting element, in particular an elastic ring, for example made of a rubber-elastic material, could alternatively be provided. The radial projection 33 or the radial projections 33 can ensure that the ring gear is held in a rotationally fixed manner on the housing 3. The counter element 7 could also be designed to be elastic, in particular axially and/or radially to the central axis, for example in order to enable a slight movement in the axial, radial and/or circumferential direction of the ring gear. The projection 33 can be arranged in a counter element 7 of the housing 3. The counter element 7 can be a form-fitting element. If necessary, a counter element 7 can be provided for each radial projection 33. The counter element 7 can in particular limit a movement of the ring gear 32 in the circumferential direction, whereby in particular a play in the axial direction can remain possible. For this purpose, the counter element 7 can in particular be designed as a groove parallel to the central axis direction.

Instead of the radial projections 33 and the counter elements 7, it can also be provided that housing elements engage in recesses of the ring gear 32 and thus also at least limit a rotation of the ring gear 32 about a central axis (not shown).

With the radial projections 33 and the counter elements 7 or alternatively with the housing elements and recesses of the ring gear 32 (not shown), in particular self-centering of the ring gear 32 can be enabled, so that a certain amount of play is present during running-in, starting and/or under load during operation of the hand-held power tool 1, so that the probability of damage to the planetary gear 30 can be reduced and thus, for example, the service life of the hand-held power tool 1 can be increased. The radial projections 33 are arranged in Fig. 4 such that they are evenly distributed over the ring gear 32, i.e. here they are arranged at an angle of 120 degrees to one another. Of course, other angles are also possible and it is also possible that the radial projections 33 are not evenly distributed.

A gear ratio of the planetary gear 30 can in particular be between 3 and 6, for example 3.6 or 4.6 or 5.5. This can mean that the sun gear 31 rotates between three and six times faster than the planet carrier 34, in particular 3.6 times, 4.6 times or 5.5 times faster. The gear ratio can be determined by suitable selection of a number of teeth of the ring gear 32, planet gear 37 and/or the sun gear 31. Also shown in Fig. 4 is that the planetary gear 30 has three planet wheels 37 with three needle bearings 38, each of which is arranged on a bearing pin 39. The bearing pins 39 can be inserted into the planet carrier 34, for example as a press fit, so that the bearing pins 39 are firmly connected to the planet carrier 34.

Fig. 5 shows a further cross section through the hand-held power tool 1 of Figs. 1 to 4 through the cutting plane designated C in Fig. 2. This cutting plane is guided through the planet carrier bearing 35 and the second central shaft bearing 14. The planet carrier bearing 35 and the second central shaft bearing 14 therefore share at least the cutting plane of Fig. 5, so that the second central shaft bearing 14 is at least partially arranged within the planet carrier bearing 35. In particular, the second central shaft bearing 14 can be arranged completely within the planet carrier bearing 35.

Fig. 6 shows a further cross section through the hand-held power tool 1 of Figs. 1 to 5 through the cutting plane designated D in Fig. 2. The output element 40 is a chain wheel 41. The chain wheel 41 drives a chain 42 or the saw chain 42. In one embodiment, as also shown in Fig. 6, the chain wheel 41 and the planet carrier 34 are designed as one piece.

The chain 42 can be guided around a chainring 43. The central shaft 11 can be substantially perpendicular to the chainring 43. This can mean in particular that an angle between the central shaft 11 and the chainring 43 is between 80 and 100 degrees, preferably between 89 and 91 degrees.

Although the invention has been described in detail, the invention is not limited to the examples disclosed and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention.

Claims

Expectations

1. Chain saw (2), with a motor (20) and a gear (30), in particular a motor-gear unit (10), and a housing (3), wherein the motor (20) and the gear (30) are at least partially arranged within the housing (3), wherein the gear (30) has a planetary gear (30), wherein the planetary gear (30) has at least one non-rotatable ring gear (32) and a sun gear (31) drivable by the motor (20) and at least one planet gear (37) mounted on a planet carrier (34), characterized in that a chain wheel (41) for driving a saw chain (42) is formed integrally with the planet carrier (34).

2. Chain saw (2) according to claim 1, wherein the chain wheel (41) formed integrally with the planet carrier (34) is mounted on the housing (3) with a planet carrier bearing (35).

3. Chain saw (2) according to claim 1 or 2, wherein the chain wheel (41) is loaded on one side, in particular when the chain saw (2) is in operation.

4. Chain saw (2) according to claims 1 to 3, wherein a central shaft (11) is mounted on the housing (3) with a first central shaft bearing (12), wherein the sun gear (31) is fixedly connected to the central shaft (11), in particular wherein the motor (20) is an electric motor (20) and a rotor (21) of the electric motor (20) is fixedly connected to the central shaft (11), preferably wherein a stator (25) of the electric motor (20) at least partially surrounds the rotor (21).

5. Chain saw (2) according to claim 4, wherein the central shaft (11) is mounted on the planet carrier (32) by a second central shaft bearing (14).

6. Chain saw (2) according to claim 5, wherein the second central shaft bearing (14) is at least partially arranged in an inner region of the planet carrier bearing (35).

7. Chain saw (2) according to claim 5 or 6, wherein the motor (20) is an electric motor (20) and a rotor (21) of the electric motor (20) is connected to the central shaft

(11) is firmly connected, wherein the rotor (21) and the sun gear (31) are arranged between the first central shaft bearing (12) and the second central shaft bearing (14).

8. Chain saw (2) according to one of claims 4 to 7, wherein the motor (20) is an electric motor (20) and a rotor (21) of the electric motor (20) is fixedly connected to the central shaft (11), wherein a fan element (51) is arranged between the rotor (21) and the sun gear (31) and is connected to the central shaft (11).

9. Hand tool (1) according to one of claims 1 to 8, wherein the planet gear (37) is mounted on the planet carrier (34) by means of a needle bearing (38).

10. Chain saw (2) according to claim 8, wherein the fan element (51) is arranged in a fan housing (54), wherein an opening (55) of the fan housing (54) is connected to a housing opening (6) of the housing (3), in particular wherein the housing opening (6) is open to the same side as another housing opening (56) for ejecting sawdust, preferably wherein the housing openings (6, 56) have an offset along the central axis to one another, in particular wherein the housing opening (6, 56) is designed to guide exhaust air along an outer hand guard area (57) of a hand guard (9).

11. Chain saw (2) according to claim 8 or 10, wherein the fan element (51) comprises an impeller (52) and a fastening element (53), wherein the fastening element (53) is fastened to the central shaft (11) and wherein the impeller (52) is fastened to the fastening element (53).

12. Chain saw (2) according to one of claims 1 to 10, wherein the ring gear (32) has at least one radial projection (33), wherein with the projection (33) in particular a rotation of the ring gear (32) about a central axis can be at least restricted, preferably wherein despite the projection tion (33) an axial movement of the ring gear (32) and/or a tilting movement of the ring gear (32) and/or a wobbling movement of the ring gear (32) along or about the central axis can be enabled.

13. Chain saw (2) according to claim 12, wherein the projection (33) is arranged in a counter element (7) of the housing (3), preferably wherein the counter element (7) is designed as a groove parallel to the central axis direction in the housing (3), in particular wherein the counter element (7) provides a rotationally fixed but not stationary receptacle for the projection (33).

14. Chain saw (2) according to claims 1 to 13, wherein the saw chain (42) is guided around a chainring (43), wherein the central shaft (11) is substantially perpendicular to the chainring (43), preferably between 89 and 91 degrees.