Hand-held power tool

Abstract

The invention relates to a hand-held power tool (1), in particular a ratchet, having a drive unit (30), an eccentric unit (22) for generating an oscillating movement, a ratchet mechanism (52) which can be driven by means of the oscillating movement, a tool holder (21) and a device (220, 221, 222, 32) for changing the transmission ratio between the drive unit (30) and the ratchet mechanism (52), wherein the eccentric unit (22) is designed to change a transmission ratio between the drive unit (30) and the ratchet mechanism (52).

Description

[0001] R. 417292

[0002] - 1 -

[0003] Description

[0004] title

[0005] hand-held power tool

[0006] State of the art

[0007] Disclosure of the invention

[0008] Document CN114227596A describes an automatic two-speed torque wrench using a planetary gear system with shift gates and steel balls for automatic switching between different operating modes.

[0009] Document US2024157536 A1 discloses a multi-speed transmission, in particular a two-stage transmission, to implement two different speed / torque levels for power tools, especially for battery-powered ratchets.

[0010] revelation

[0011] The hand-held power tool according to the invention, with the features of claim 1, has the advantage that an eccentric unit is designed to effect a change in the gear ratio between the drive unit and the ratchet mechanism. This enables, for example, the integration of two operating modes, such as a high-speed mode for fast screwdriving and a high-torque mode for powerful screwdriving, in a single compact hand-held power tool, in particular a ratchet. This eliminates the need to switch between different tools or manual settings, which increases work efficiency and improves user comfort. In contrast to hand-held power tools, especially fixed-ratio ratchets, which are optimized for either speed or torque, the ratchet according to the invention offers the flexibility to meet both requirements in one device. This is R. 417292

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[0013] This is particularly advantageous in applications where both rapid insertion and powerful tightening of screws are required.

[0014] The hand-held power tool can be a portable power tool used for performing manual tasks, in particular for tightening or loosening screws and other fasteners. In a preferred embodiment, the hand-held power tool is a ratchet that generates an oscillating motion and is particularly connected to a ratchet mechanism. Interposed means, for example a ratchet mechanism, are included to convert a rotary motion of the eccentric unit into an oscillating motion. The ratchet mechanism can be driven, in particular by means of the oscillating motion, to enable the tightening or loosening of screws. The hand-held power tool according to the invention is characterized in particular by its compact design and low weight, which is especially advantageous when working in confined spaces or overhead.

[0015] The drive unit is the part of the hand-held power tool that provides the drive, preferably designed as an electric motor, and particularly preferably as a brushless electric motor. The drive unit is designed to drive a drive shaft. In particular, the drive unit is designed to drive the eccentric unit indirectly, especially by means of the drive shaft.

[0016] The eccentric unit comprises, in particular, an eccentric shaft and an eccentric pin. These are arranged, in particular, in parallel but not collinearly. The eccentric unit is designed, in particular, to transmit a rotary motion eccentrically. The eccentric unit is designed, in particular, to transmit a rotary motion eccentrically. The eccentric unit is operatively connected, in particular, to a bushing for receiving the eccentric pin. The eccentric unit is designed, in particular, to achieve different gear ratios through different rotational positions of the eccentric pin.

[0017] According to the invention, the eccentric unit is designed such that the hand-held power tool can be switched between at least two different gear ratios. In particular, the eccentric unit is designed to have a first eccentricity and a second eccentricity, between which the eccentric unit R. 417292

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[0019] The eccentric unit is switchable to achieve the two different translations. Furthermore, it is specifically designed to be switchable between two different rotational positions, with the first eccentricity being present in a first rotational position and the second eccentricity being present in a second rotational position.

[0020] The oscillating motion is, in particular, a reciprocating motion that can be transmitted to a fork of an output unit. The fork is, in particular, in operative connection with the bushing. The oscillating motion of the fork is transmitted to the fork, in particular, via the bushing that receives the eccentric pin. The fork is, in particular, a lever that converts the motion of the eccentric unit into an amplified or reduced oscillating motion. The ratchet mechanism is, in particular, designed to transmit the oscillating motion of the fork to the tool holder.

[0021] The ratchet mechanism itself operates primarily by means of a pawl device that transmits the oscillating movements to the tool holder. The pawl device ensures that the rotary motion is transmitted only in one specific direction, while it can freely rotate in the opposite direction. This allows a user, for example, to efficiently tighten or loosen screws or other fasteners without the tool becoming jammed during the return stroke. Additionally, and most importantly, the handheld power tool features a direction-of-rotation lever designed to actuate the pawl device. This arrangement allows the user to precisely control the tool's direction of rotation. This, for example, improves the handling and user-friendliness of the handheld power tool.

[0022] Preferably, the gear ratio can be changed by positioning the eccentric unit between two eccentricities, each formed by a distance between an eccentric pin axis and the axis of rotation of the drive shaft, thereby making it possible, in particular, to achieve different gear ratios between a drive shaft of the drive unit and the ratchet mechanism. R. 417292

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[0024] Preferably, the eccentric unit has a first eccentricity and a second eccentricity, and the gear ratio can be changed by switching from the first to the second eccentricity. This means that the eccentric unit can be arranged in two different positions relative to the drive shaft, each defining a different eccentricity and thus a different gear ratio. The first eccentricity corresponds, for example, to a high-speed mode with high rotational speed and low torque, while the second eccentricity corresponds to a high-torque mode with low rotational speed and high torque. Switching between the two eccentricities results in a change in the rotational position of the eccentric unit. This, in particular, alters the distance between the center of rotation of the eccentric and the axis of rotation of the drive shaft, which directly affects the gear ratio.

[0025] Preferably, the eccentric unit is rotatably mounted with respect to the drive shaft. In particular, the eccentric unit is partially rotatable with respect to the drive shaft. The partially rotatable mounting means that the eccentric unit is not fully rotatable with respect to the drive shaft. The rotatable mounting of the eccentric shaft means, in particular, that it is not rigidly connected to the drive shaft, but is fixed against rotation with respect to driving the tool holder on the drive shaft, thus allowing relative movement between the two shafts. "Partially rotatable" means that the eccentric shaft is not fully rotatable, in particular not through 360° about an eccentric axis.

[0026] Preferably, the eccentric shaft is supported by a rolling or sliding bearing. In a preferred embodiment, however, the eccentric shaft is connected to the drive shaft by means of a sliding bearing. For example, the drive shaft has a sliding bearing inside or on its outer surface, in or on which the eccentric shaft rotates.

[0027] Preferably, the eccentric unit is switchable between two defined rotational positions, wherein a first rotational position defines the first eccentricity and a second defined rotational position defines the second eccentricity between an eccentric pin axis and the axis of rotation of the drive shaft, thereby particularly enabling different R. 417292

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[0029] Translations between a drive shaft of the drive unit and a ratchet mechanism are possible.

[0030] Preferably, the eccentric unit is designed such that the eccentric pin can assume two defined positions. In particular, the eccentric unit is switchable between two rotational positions such that the eccentric pin can assume two different defined positions relative to the drive shaft. This results in two different eccentricities.

[0031] A defined position means, in particular, that the eccentric pin is fixed in a specific orientation or position relative to the drive shaft. For example, with a selected direction of rotation, the configuration is predetermined, especially at least after a settling time following the change in direction. The settling time is, in particular, the time the eccentric pin needs to move from the first defined position to the second defined position. Specifically, each defined position can be associated with a specific operating state, for example, high speed or high torque.

[0032] Preferably, the eccentric shaft is arranged eccentrically to an axis of rotation of the drive shaft. This eccentric arrangement results in a first eccentricity that defines the distance between the eccentric axis and the axis of rotation of the drive shaft.

[0033] Preferably, the drive shaft is designed as a hollow shaft and accommodates at least part of the eccentric shaft within its interior. The hollow shaft is, in particular, a shaft with a continuous axial cavity, preferably a bore, and accommodates at least parts of the eccentric shaft within its interior. The hollow shaft design particularly allows the integration of the switching mechanism for the two gear ratios within the compact frame of the drive shaft, contributing to a robust and space-saving design. R. 417292

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[0035] Preferably, the drive shaft has a first stop and a second stop designed to limit the eccentric shaft to two defined rotational positions. These stops interact with the eccentric shaft and prevent it from rotating beyond these defined positions. These two defined rotational positions correspond to the two gear ratios of the power tool, enabling, for example, a high-speed mode and a high-torque mode. Precise limitation of the rotational positions ensures reliable and repeatable switching between the two gear ratios. In particular, the stops on the drive shaft and / or the eccentric shaft can be planar stops, such as projections or ridges, which preferably abut each other and limit the rotation.These surfaces can have various shapes, for example, planar, rounded, or concave / convex. This allows for optimization of force transmission and wear. Furthermore, the stops can be designed as detent mechanisms, for example, with a spring and a pin or ball detent.

[0036] Preferably, the first stop and the second stop are integrally formed with the drive shaft. This means that the stops are, in particular, integral components of the drive shaft, for example, through features such as contours, protrusions, or recesses, or as a result of machining.

[0037] Preferably, the first stop and the second stop are arranged at an angle to each other, with the included angle being in the range of 70°–130°, preferably 90°–120°, and particularly preferably 95°–105°. The included angle results, for example, and in particular, from the two intersecting contact surfaces.

[0038] Preferably, the first stop is designed as a planar contact surface, and / or the second stop is designed as a planar contact surface, as a second contact surface. In particular, the first stop surface and / or the second stop surface have a planar contact surface in a radial direction of the drive shaft, which corresponds to at least 40%, preferably at least 50%, of the diameter of the eccentric shaft. A larger contact area compared to a linear contact surface distributes the forces more evenly and reduces surface pressure. This minimizes the [R. 417292].

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[0040] Reduces wear on the stops and the eccentric shaft, increasing the lifespan of the mechanism.

[0041] Preferably, the eccentric unit has a stop cam arranged on an end face of the eccentric shaft facing the tool holder. The stop cam interacts, in particular, with the stops on the drive shaft and thus defines the two rotational positions of the eccentric shaft. Preferably, the stop cam is symmetrical. In particular, "symmetrical" refers to a symmetry of the contact surfaces.

[0042] Preferably, the eccentric pin is arranged on the stop cam. The connection between the eccentric pin and the stop cam can be realized in various ways. In one embodiment, the eccentric pin and the stop cam are manufactured in one piece, for example by milling, turning, or sintering. In another embodiment, the eccentric pin and the stop cam are positively connected, with the eccentric pin being pressed, inserted, or clamped into a recess in the stop cam. Alternatively or additionally, the stop cam can have a bore into which the eccentric pin is inserted and fixed.

[0043] In particular, the eccentric pin and stop cam are bonded together by a material-bonded connection. For example, by welding, soldering, or gluing. Alternatively or additionally, the eccentric pin can also be screwed to the stop cam.

[0044] Preferably, the eccentric pin axis is arranged differently from the central axis of the eccentric shaft. This means that the eccentric pin is not located in the center of the eccentric shaft, but offset. This eccentric arrangement of the eccentric pin particularly enhances the effect of the eccentricity of the eccentric shaft. This results, in particular, in a first overall eccentricity when added to the eccentricity of the eccentric shaft. In a second defined position of the eccentric pin, a second overall eccentricity results, which has a different value than the first overall eccentricity. This makes it possible, in particular, to separate two gear ratios. R. 417292

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[0046] The overall eccentricity particularly affects the amplitude of the oscillating motion of the rocker arm and the resulting torque at the output.

[0047] Preferably, the hand-held machine tool includes a control unit designed to control a direction of rotation of the drive shaft, in particular to switch the eccentric unit between the first eccentricity and the second eccentricity.

[0048] Preferably, the second eccentricity (high-torque mode) has a greater eccentricity than the first eccentricity (high-speed mode). This greater eccentricity results in a longer lever arm between the eccentric pin and the fork. Consequently, the swingarm moves at a smaller angle but with higher torque. This allows for powerful tightening of bolts in high-torque mode. Conversely, the smaller eccentricity in high-speed mode results in a shorter lever arm and greater swingarm deflection, achieving a higher rotational speed but with lower torque.

[0049] Preferably, the eccentric unit has a first eccentricity radius in the first defined rotational position and a second eccentricity radius in the second defined rotational position, the first eccentricity radius being smaller than the second eccentricity radius. In particular, the eccentric pin has a different distance from the axis of rotation of the drive shaft in each defined rotational position, resulting in different lever ratios and thus the two gear ratios. The switching between the rotational positions preferably occurs automatically by reversing the direction of rotation of the drive shaft.

[0050] In particular, a sensor unit detects the motor current of the electric motor. Specifically, the control unit is designed to change the direction of rotation of the drive shaft depending on the detected motor current. Specifically, the control unit is designed to change the direction of rotation of the drive shaft when the motor current reaches or exceeds a predetermined threshold. R. 417292

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[0052] Preferably, the hand-held power tool is a cordless ratchet, in particular a 12V cordless ratchet. Preferably, the hand-held power tool has an output housing that encloses the eccentric unit, the rocker arm, and the ratchet mechanism.

[0053] Brief description of the characters

[0054] Fig. 1 shows an embodiment of an electrically driven ratchet in a side view,

[0055] Fig. 2 shows a sectional view of the preferred embodiment of the electrically driven ratchet according to Fig. 1 ,

[0056] Fig. 3 shows part of an output unit of the ratchet in an isometric view,

[0057] Fig. 4 shows a drive shaft in a preferred embodiment,

[0058] Fig. 5 shows an eccentric unit in a preferred embodiment,

[0059] Fig. 6 shows a frontal view of the drive shaft from Figure 4 and,

[0060] Fig. 7 schematic sectional view of a part of the output unit.

[0061] Identical elements or elements with the same function are marked with the same reference symbols in the figures.

[0062] Figure 1 shows a preferred embodiment of an electrically driven ratchet 1 (hereinafter referred to as "ratchet") in a side view.

[0063] The ratchet 1 is a mechanical device used to tighten or loosen a fastener 213, such as screws or nuts. Unlike conventional ratchets, the driven ratchet 1 has features that improve its functionality and efficiency. In the preferred embodiment shown in Figure 1, the ratchet 1 is electrically driven by a drive unit 30 and includes a battery pack 6. The drive unit 30 (Fig. 2)R. 417292

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[0065] This generates a torque that is required for tightening or loosening screws 213.

[0066] The handle housing 4 of the ratchet 1 serves primarily to form a handle for the ratchet 1. The handle housing 4 is designed so that it can be gripped by a user with one hand. The handle housing 4 enables the user to grip and operate the ratchet securely, ensuring ergonomic and comfortable handling.

[0067] The handle housing 4 has an operating side 104 which includes an actuating device 80 in the form of a pawl 83. The pawl 83 enables the user to activate and control the ratchet 1. The operating side 104 is designed in such a way as to allow intuitive and user-friendly operation by means of the large pawl 83, which is easily accessible and simple to operate.

[0068] The handle housing 4 includes, in particular, a lock-off button 43, which forms a safety mechanism for an electrical switch 81 (shown in Fig. 2). The electrical switch 81 can be actuated by means of the pawl 83, the pawl 83 being rotatably mounted in a pivot point 84. The pivot point 84 of the pawl 83 can, for example, be a sliding bearing (not shown) in the handle housing 4.

[0069] The handle housing 4 has an air inlet 41 in the form of an opening through which ambient air can be drawn in and, in particular, can flow out again through an air outlet 31 on a drive housing 3. This serves, in particular, to cool the ratchet 1 or the drive unit 30 (Figure 2) and to ensure air circulation inside the housings 3, 4. In other embodiments, the air inlet 41 can have a different shape, for example, in the form of small grilles or slots that direct air into the housing 4. Furthermore, an air filter (not shown) can be attached to the air inlet 41 to prevent the ingress of dirt, dust, and other contaminants into the housing 4. R. 417292

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[0071] The ratchet 1 has a work light 44, which is arranged at a first end 401 of the ratchet 1, on a side facing the tool holder 21. The work light 44 is, in particular, an integrated light source and is suitable for illuminating the working area of ​​the ratchet 1. In the embodiment shown, the work light 44 is designed as an LED lamp, which is activated when the pawl 83 is actuated. In a further embodiment, the work light 44 can be equipped with a switch to turn the light on and off as needed. A user can, for example, operate the ratchet more safely and precisely, especially in poorly lit environments.

[0072] A battery pack receptacle 5 is arranged in a region of a second end 402 of the ratchet 1. The battery pack receptacle 5 is a device or opening that serves to detachably receive and secure a battery pack 6 in order to supply the ratchet 1 with electrical energy. This battery pack receptacle 5 has a mechanical and electrical interface for connecting the battery pack 6 electrically and mechanically to the ratchet 1.

[0073] A charge level indicator 42 is arranged in the region of the second end 402 of the handle housing 4. Specifically, the charge level indicator 42 is located on one side 105 of the handle. The charge level indicator shows the user the current charge level of the battery pack 6a, 6b. The charge level indicator 42 can be implemented in various ways, such as using LEDs, LCD displays, or digital displays. In the illustrated preferred embodiment, the charge level indicator 42 uses multiple LEDs. The charge level indicator 42 can also display the remaining charge level as a bar graph or percentage. Furthermore, different colors can be used for the charge level indicator 42 to indicate the charge level of the battery pack 6. For example, green for a full battery, yellow for a medium charge level, and red for a low charge level.

[0074] In the embodiment shown, the handle housing 4 and the battery pack receptacle 5 are made in one piece.

[0075] Furthermore, the handle housing accommodates 4 electronic components 8. The electronic components 8 include, for example, the electrical switch 81, a R. 417292

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[0077] A circuit board 82 and a plurality of electrical conductors 85 for conducting electrical current and / or signals. A battery pack 6 and the circuit board 82 are arranged overlapping each other. This enables, in particular, a compact design. The overlap is more than 38%. In particular, an actuating axis 810 of the switch 81 intersects the circuit board 82. The illustrated embodiment includes a sensor unit 86, which can, among other things, measure a motor current 505-507. This enables, for example, automatic shutdown to prevent overload or damage to fastening elements 213.

[0078] The ratchet 1 further comprises a drive housing 3. The drive housing 3 is connected to the handle housing 4 at its first end 401 in an axial direction along the longitudinal axis 100, for example by means of fasteners 48. The drive housing 3 is inserted into the handle housing 4 in the connection area.

[0079] The drive unit 30 shown in Figure 2 is arranged in the drive housing 3, whereby, due to the partial insertion of the drive housing 3 into the handle housing 4, the drive unit 30 is also partially arranged within the handle housing. The drive unit 30 is an electric motor 30, which has a drive shaft 32. The drive shaft 32 is supported in the drive housing 3, in particular by means of a bearing 33. The drive shaft 32 defines a longitudinal axis 100 of the ratchet 1. In particular, the ratchet 1 extends along the longitudinal axis 100. The drive housing 3 is detachably connected to the handle housing 4 at a first end 401 in the axial direction of the longitudinal axis 100.

[0080] The ratchet 1 further comprises a gear unit 70, which translates the torque generated by the electric motor 30. The gear unit 70 preferably has a planetary gear set. The gear unit 70 is screwed to the drive housing 3. The gear unit 70 is screwed to the drive housing 3 by means of an external thread in its encapsulation. The gear unit 70 is screwed to an output unit 2. In addition to translating the torque, the gear unit 70 also performs a connecting function. The gear unit 70 connects the output unit 2 and the drive housing 3 in such a way that the torque generated by the electric motor 30 can be transmitted to the output unit 2. R. 417292

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[0082] The output unit 2 comprises, in particular, an output housing 24, which accommodates an eccentric unit 22 and at least parts of the tool holder 21, along with a direction-of-rotation lever 23. The eccentric unit 22 is configured to convert a rotary motion of the drive shaft 32 into an oscillating or reciprocating motion, which is transmitted to the tool holder 21, in particular by means of a ratchet mechanism having a pawl device (shown in Fig. 3). The direction-of-rotation lever 23 is configured to act on the pawl device so that the tool holder 21 operates in one direction of rotation for fastening and can rotate freely in the opposite direction. The tool holder 21 is configured to receive a tool 212 on a tool-changing device 210. For example, socket wrenches can be used with the tool 212 to tighten or loosen screws 213 or nuts.Furthermore, extensions, adapters, joints and / or bit attachments can be mounted on the tool holder 21. The tool changing device 210 has a square drive, for example in a size of 1 / 4 inch, 3 / 8 inch or 1 / 2 inch, on its outer surface.

[0083] Figure 3 shows a section of the output unit 2. The drive shaft 32 is rotatably mounted about its axis of rotation 320. In the section shown, the drive shaft 32 is supported by two needle bearings 50 (for illustrative purposes, only one needle bearing 50 is shown). The needle bearings 50 are axially supported by a collar 322, which is integrally formed with the drive shaft 32. A first stop surface 323 and a second stop surface 324 (shown in Figure 4) extend directly from an end face of the collar 322 at right angles to the end face of the collar 322. The stop surfaces 323, 324 can, for example, be machined from the drive shaft 32 by a machining process. The stop surfaces 323, 324 are integrally formed with the collar 322. The stop surfaces 323, 324 are integrally formed with the drive shaft 32.

[0084] The eccentric unit 22 is partially inserted into the drive shaft 32 and rotatably mounted. The rotational movement of the eccentric unit 22 relative to the drive shaft 32 is limited by the stop cam 221, which interacts with the stop surfaces 323, 324 on the drive shaft 32. The stop cam 221 has a first R. 417292

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[0086] The drive shaft 32 has two cam stop surfaces: one 230 and a second 231 (not shown). In Figure 3, the second 231 cam stop is in contact with the second stop surface 324 (Figure 4). When the drive shaft 32 rotates counterclockwise, the contact between the stop surface 324 and the cam stop surface 231 creates a positive connection between the drive shaft 32 and the eccentric unit 22. When rotating clockwise, the first stop surface 323 engages with the first cam stop surface 230. The eccentric unit 22 can thus be switched between two defined rotational positions. These rotational positions define two different eccentricities (250, 251) between the eccentric pin axis 224 and the rotational axis 320 of the drive shaft, thereby achieving different gear ratios between the drive shaft 32 and the ratchet mechanism 52. The origin of eccentricities 250 and 251 is explained in more detail below with reference to Figures 4, 5 and 6.

[0087] Figure 3 also shows a bushing 51 that converts the rotary motion of the eccentric unit 22 into an oscillating motion of the fork 53. The fork 53 drives the ratchet mechanism 52 and thus the tool holder 210.

[0088] Figures 4 and 6 show the drive shaft 32 in a close-up view and a frontal view, respectively. Both figures show the eccentric bore 325, which, as is particularly evident in Figure 6, is arranged eccentrically. The eccentric unit 22, more precisely the eccentric shaft 220 (Fig. 5), is mounted in the eccentric bore 325 of the drive shaft by means of a sliding bearing. The eccentric bore 325 makes the drive shaft 32 a hollow shaft.

[0089] Figure 5 shows the eccentric unit 22 in detail. The eccentric shaft 220 is defined by its eccentric axis 223. The stop cam 221 is arranged on the end face of the eccentric shaft 220. This is preferably formed integrally with the eccentric shaft 220, but can also be made of multiple parts. The eccentric pin 222 is located on the stop cam 221 and has a central axis as the eccentric pin axis 224.

[0090] The first stop surface 323 and the second stop surface 324 are arranged at an angle 326 of 100° to each other. The stop surfaces 323, 324 are planar and R. 417292

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[0092] The design provides a sufficiently large contact surface for the stop cam 221 to transmit the required torques, for example, up to 100 Nm. The length of the surfaces parallel to a radial direction of the eccentric bore 325 is at least 40%, preferably at least 50%, of the diameter of the eccentric shaft. The height of the stop surfaces 323, 324 in an axial direction of the drive shaft 32, starting at an end face of the collar, is in the range of 1 mm to 10 mm, preferably 2 mm to 8 mm, and particularly preferably 2 mm to 5 mm.

[0093] The first eccentricity 250 and the second eccentricity 251 each have a constant base component 326, which is derived from a fixed distance between the eccentric axis 223 and the axis of rotation of the drive shaft 320. The stop cam 221, which has two defined stop surfaces 323, 324 on the drive shaft 32 during rotation and can be switched between them, results in two different additional components for the first eccentricity 250 and the second eccentricity 251. These additional components are summed to form the constant component.

[0094] This results in different leverage ratios between the eccentric pin 220 and the fork 53, and thus different gear ratios between the drive shaft 32 and the ratchet mechanism 52.

[0095] The first eccentricity 250 and the second eccentricity 251 are resulting eccentricities. The first eccentricity 250 and the second eccentricity 251 are defined as the distance of the eccentric pin axis 224 to the axis of rotation 320 of the drive shaft 32. The first eccentricity 250 corresponds, for example, to a high-speed mode with high rotational speed and low torque, while the second eccentricity 251 corresponds to a high-torque mode with low rotational speed and high torque.

[0096] Figures 7a and 7b, based on longitudinal sections of the ratchet 1, schematically illustrate the first eccentricity 250 and the second eccentricity 251 in a section of the ratchet 1 corresponding to Figure 3. This shows that the second eccentricity 251 is greater than the first eccentricity 250, resulting in different gear ratios in the two rotational positions of the eccentric unit 22.

Claims

R. 417292 - 16 - Claims 1. Hand-held power tool (1), in particular a ratchet, comprising a drive unit (30), an eccentric unit (22) for generating an oscillating motion, a ratchet mechanism (52) which can be driven by means of the oscillating motion, a tool holder (21) and a device (220, 221, 222, 32) for changing the transmission between the drive unit (30) and the ratchet mechanism (52), characterized in that the eccentric unit (22) is designed to change a transmission between the drive unit (30) and the ratchet mechanism (52).

2. Hand-held power tool according to claim 1, characterized in that the eccentric unit (22) has a first eccentricity (250) and a second eccentricity (251) and the ratio can be changed by switching from the first eccentricity (250) to the second eccentricity (251).

3. Hand-held power tool according to one of claims 1 or 2, characterized by an eccentric pin axis (224) of an eccentric pin (222) which is arranged differently from an eccentric axis (223) of the eccentric shaft (22).

4. Hand-held power tool according to one of the preceding claims, characterized in that the eccentric unit (22) is switchable between two defined rotational positions which define the first eccentricity (250) and the second eccentricity (251) between the eccentric pin axis (224) of the eccentric pin (222) and a rotational axis (320) of a drive shaft (32).

5. Hand-held power tool (1) according to one of the preceding claims, characterized in that the eccentric unit (22) is rotatably mounted with respect to a drive shaft (32) of the drive unit (30). R. 417292 - 17 - 6. Hand-held power tool according to claim 4, characterized in that the eccentric shaft (220) of the eccentric unit (220) is mounted on the drive shaft (32) by means of a rolling or sliding bearing (325a).

7. Hand-held power tool (1) according to claim 5, characterized in that the eccentric shaft (220) is arranged eccentrically (326) to an axis of rotation (320) of the drive shaft (32).

8. Hand-held power tool (1) according to one of claims 3 to 7, characterized in that the drive shaft (32) is designed as a hollow shaft and the eccentric shaft (220) is accommodated at least in part in its interior, in particular in an eccentric bore (325).

9. Hand-held power tool (1) according to one of claims 4 to 7, characterized in that the drive shaft (32) has a first stop (323) and a second stop (324) which are designed to limit the eccentric shaft (220) in the two defined rotational positions.

10. Hand-held power tool (1) according to claim 9, characterized in that the first stop (323) and the second stop (324) are integrally formed with the drive shaft (32).

11. Hand-held power tool (1) according to claim 9 or 10, characterized in that the first stop (323) and the second stop (324) are arranged at an angle, wherein the enclosed angle (326) is in a range of 70°-130°, preferably 90° - 120°, particularly preferably 95° - 105°.

12. Hand-held power tool (1) according to one of claims 9 to 11, characterized in that the first stop (323) is designed as a flat surface, as a first stop surface (323), and / or the second stop (324) is designed as a flat surface, as a second stop surface (324).

13. Hand-held power tool (1) according to one of the preceding claims, characterized in that the eccentric unit (22) has a stop cam (221), R. 417292 - 18 - which is arranged on one end face of the eccentric shaft (220) facing the tool holder (21) and is in particular symmetrical to a central plane (226) of the stop cam (221).

14. Hand-held power tool according to claim 13, characterized in that the eccentric pin (222) of the eccentric unit (22) is arranged on the stop cam (221).

15. Hand-held power tool according to one of claims 2-14, characterized in that the hand-held power tool comprises a control unit (87) which is designed to control a direction of rotation of the drive shaft (32), in particular to move the eccentric unit (22) between that of the first eccentricity (250) and that of the second eccentricity (251).

16. Hand-held power tool according to any one of claims 2 to 15 preceding claims, characterized in that the first eccentricity (250) has a greater eccentricity than the second eccentricity (250).

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