Hand-held machine tool

Abstract

The invention relates to a hand-held power tool, in particular a grinding machine (10), with an eccentric gear (40) arranged in a machine housing (11) and an electric or pneumatic drive motor (30) for rotary driving of a drive shaft (35) of the eccentric gear (40) about a drive axis (A), wherein the eccentric gear (40) has a tool shaft (50) which is rotatably mounted eccentrically on the drive shaft (35) by means of at least one tool shaft bearing (42, 44) to perform eccentric movements and has a tool holder (51) for a disc tool (14), wherein a forced rotation guide (54) is provided which, in a forced rotation eccentric mode, forces rotational movements of the tool shaft (50) with respect to the machine housing (11) by means of a rolling element (55) of the forced rotation guide (54) engaging another rolling element (57) of the forced rotation guide. (54) shifts,wherein one rolling element (57) is supported on the machine housing (11) and the other rolling element (55) is supported on the tool shaft (50). A freewheeling device (62) is provided between at least one of the rolling elements (57) and the tool shaft (50) or the machine housing (11). This freewheeling device couples the at least one rolling element (57) to the machine housing (11) or the tool shaft (50) in a rotationally fixed manner in a first direction of rotation of the tool shaft (50), which corresponds to a locking direction of the freewheeling device (62), so that one rolling element (55) supported on the tool shaft (50) can roll on the other rolling element (57) supported on the machine housing (11). In a second direction of rotation of the tool shaft (50), which corresponds to a freewheeling direction of the freewheeling device (62), the freewheeling device (62) is rotatably released, so that the tool shaft (50) can rotate with respect to the machine housing (11) without relative rotation of the rolling elements (55, 57) relative to each other.

Description

[0001] The invention relates to a hand-held power tool, in particular a grinding and / or polishing machine, with an eccentric gear arranged in a machine housing and an electric or pneumatic drive motor for rotary driving of a drive shaft of the eccentric gear about a drive axis, wherein the eccentric gear has a tool shaft which is rotatably mounted eccentrically on the drive shaft by means of at least one tool shaft bearing for carrying out eccentric movements and has a tool holder for a disc tool, in particular a grinding or polishing disc, wherein a forced rotation guide is provided which, in a forced rotation eccentric mode, forces rotational movements of the tool shaft with respect to the machine housing by means of a rolling element of the forced rotation guide rolling against another rolling element of the forced rotation guide.wherein one rolling element is supported on the machine housing and the other rolling element on the tool shaft.

[0002] Such a hand-held machine tool is described, for example, in DE 10 2010 012 025. The operator can manually switch the machine between forced rotation eccentric mode and a freewheel eccentric mode. In forced rotation eccentric mode, the tool shaft makes defined rotary movements by means of a planetary gear connected to the tool shaft rolling against a ring gear supported on the machine housing. When the ring gear is disengaged from the planetary gear, the tool shaft can rotate relatively freely and is driven by at least one tool shaft bearing.

[0003] However, switching between operating modes is complex.

[0004] It is therefore the object of the present invention to provide an improved operating concept for a hand-held machine tool, in particular a grinding machine or polishing machine.

[0005] To solve the problem, a hand-held machine tool of the type mentioned above is provided with a freewheel device arranged between at least one of the rolling elements and the tool shaft or the machine housing. This freewheel device supports the at least one rolling element on the machine housing or the tool shaft in a first direction of rotation of the tool shaft, corresponding to a locking direction of the freewheel device, with a supporting force suitable for rolling the other rolling element. In particular, it couples the rolling element in a rotationally fixed manner, so that the one rolling element supported on the tool shaft can roll on the other rolling element supported on the machine housing. In a second direction of rotation of the tool shaft, corresponding to a freewheel direction of the freewheel device, the freewheel device is rotatably released.so that the tool shaft can be rotated relative to the machine housing without relative rotation of the rolling elements against each other, and / or the rolling element supported on the tool shaft can rotate with the rolling element supported on the machine housing, and / or the rolling element associated with the tool shaft can be held completely or substantially rotationally fixed by the rolling element associated with the machine housing.

[0006] In the second direction of rotation, it is possible that the rolling element supported on the tool shaft can rotate with the rolling element supported on the machine housing. However, it is also possible that the rolling element associated with the tool shaft is rotatable in the second direction of rotation, so that it can be held stationary or essentially stationary against the rolling element supported on the machine housing, which is not rotatable in the second direction of rotation.

[0007] The underlying principle is that reversing the direction of rotation of the tool shaft activates or deactivates the forced rotation eccentric mode. The forced rotation eccentric mode is therefore active in the first direction of rotation of the tool shaft, allowing the forced rotation guide to impose a specific rotation relative to the machine housing. In this case, the freewheel mechanism locks. Consequently, the rolling element can no longer rotate freely relative to the component against which it is supported by the freewheel mechanism, i.e., the machine housing or the tool shaft.

[0008] However, when the tool shaft rotates in the second direction, the rolling element that was supported in the first direction of rotation of the tool shaft or the locking direction of the freewheel mechanism is released. It can therefore rotate freely and be carried along by the other rolling element, for example, or remain supported by the other rolling element. Thus, it is possible that the tool shaft is no longer guided by the forced rotation guide, i.e., it is no longer in forced rotation eccentric mode.

[0009] The forced rotation eccentric mode is therefore activated in the locking direction of the freewheel device, and deactivated in the freewheel direction of the freewheel device.

[0010] In the forced rotation eccentric mode, the tool shaft expediently performs a forced rotation around the drive axis, changing its angle of rotation relative to the machine housing of the hand-held machine tool, by means of the forced rotation guide.

[0011] In the forced rotation eccentric mode, it is advantageous for the freewheel mechanism to lock completely, thus completely preventing any movement of the locked rolling element relative to the component against which it is supported by the freewheel mechanism. For example, a ring gear can no longer rotate relative to the machine housing in this case. However, it is also possible for the freewheel mechanism to provide a lesser support force in the locked position compared to a complete blockage of the rolling element, instead providing a rotational restraint. In this case, the rolling element is not completely blocked relative to the supporting component, i.e., the machine housing or the tool shaft, but it cannot rotate freely; its rotational movement is restricted.The support force can therefore be somewhat less than a force required to completely lock or block a relative movement of the supported rolling element to the supporting component, the machine housing or the tool shaft.

[0012] When the forced rotation eccentric mode is deactivated, a free rotation eccentric mode is present. For example, it is intended that the tool shaft is in a free rotation eccentric mode in the second direction of rotation, in which the tool shaft performs rotational movements due to bearing friction of at least one tool shaft bearing when the drive shaft rotates, and is freely rotatable with respect to the drive axis. It is understood that the mobility is still limited by a certain amount of bearing friction, but is to be understood as free mobility in the sense that the previously supporting rolling element can be carried along by the other rolling element.

[0013] The hand-held machine tool expediently includes braking means for slowing down the tool shaft or the disc tool mounted on it. The braking means comprise, for example, a brake element, a sealing sleeve, or other braking devices that act on the tool shaft or the tool, or both. The braking means are specifically intended for operation of the hand-held machine tool with the forced rotation eccentric mode switched off.

[0014] Preferably, one of the rolling elements is a ring gear and the other is a planet gear. The planet gear is mounted within the ring gear and can roll against it. For example, the ring gear is associated with the machine housing, while the planet gear is associated with the tool shaft. However, the reverse configuration is also possible, in which a planet gear is provided on the machine housing, around which the ring gear, in turn, rotates, and which is fixed to the tool shaft.

[0015] In principle, it is also conceivable that one of the rolling elements is designed as a sun wheel, around which a rolling element designed as a planet wheel revolves, so to speak, or a planet wheel rolls.

[0016] It is preferred that the rolling elements have teeth so that their teeth mesh with each other. However, it is also possible that the rolling elements move against each other by friction, i.e., that one rolling element rolls or glides against the other rolling element when the first direction of rotation is set and the freewheel mechanism is in the locking position.

[0017] For example, it is possible that only one of the rolling elements is supported by a freewheel device with respect to the tool shaft or the machine housing. Therefore, only a single freewheel device can be provided, as is also shown in the drawing.

[0018] The hand-held power tool can also have multiple freewheel devices. For example, one freewheel device may be arranged between the rolling element associated with the tool shaft and the tool shaft itself, while another freewheel device may be arranged between the machine housing and the rolling element associated with the machine housing. It is possible, for instance, that one of these freewheel devices, in its locked position, completely blocks the rotational movement of the rolling element attached to it, while the other freewheel device, in its locked position, brakes the rolling element attached to it, thus inhibiting its rotational movement or mobility. The other freewheel device therefore does not completely block the rotational movement of the rolling element assigned to it.

[0019] It is possible that the rolling element, which can be supported in a rotationally fixed manner with respect to the machine housing or the tool shaft by means of the at least one freewheel device, can be rotated with respect to the machine housing or the tool shaft by means of a rotary bearing, in particular a rolling bearing, especially preferably a ball bearing, when the freewheel device assumes the freewheel direction or the tool shaft rotates in the second direction of rotation.

[0020] Preferably, the freewheeling device is arranged on a bearing or forms part of a bearing with which the rolling element is rotatably mounted relative to the machine housing or the tool shaft. For example, it is possible to use a bearing, in particular a rotary bearing, and most preferably a ball bearing, which has an integral freewheeling device.

[0021] It is preferred if the at least one tool shaft bearing comprises a first and a second tool shaft bearing that are spaced apart with respect to the drive axis or the longitudinal extent of the drive shaft. It is particularly preferred if the two tool shaft bearings are provided at the respective longitudinal end regions of the tool shaft and / or the respective longitudinal end regions of the drive shaft.

[0022] It is possible that the tool shaft is a hollow shaft with the drive shaft located inside it. In any case, it is possible that the drive shaft is located within or engages with an interior space of the tool shaft. For example, the tool shaft may be mounted eccentrically on the outside of the drive shaft.

[0023] A preferred variant is one in which the drive shaft has an interior space, for example, a hollow shaft, in which the tool shaft is arranged. It is advantageous if the drive shaft has a hollow shaft or is designed as a hollow shaft in which the tool shaft is arranged.

[0024] Advantageously, the tool shaft is mounted eccentrically in the drive shaft. The at least one tool shaft bearing is, for example, located inside the drive shaft and supports the tool shaft.

[0025] The following configuration is possible both when the drive shaft is a hollow shaft that accommodates the tool shaft and when the tool shaft is a hollow shaft in which the drive shaft is accommodated.

[0026] It is advantageous for the tool shaft to project in front of the drive shaft at an area facing away from the tool holder and to carry one of the rolling elements, for example the planetary gear or a ring gear.

[0027] Advantageously, the drive motor is arranged between the tool holder and at least one of the rolling elements, for example a planetary gear. This results in a favorable weight distribution.

[0028] A preferred concept provides that the drive motor is arranged between the tool holder and at least one of the rolling elements and / or the freewheel device.

[0029] It is particularly preferred if the drive motor is arranged between the tool holder and the forced rotation guide.

[0030] It is possible for the drive motor to directly drive the drive shaft. For example, the drive motor is a direct drive. In particular, the drive shaft is preferably provided or formed by the motor shaft of the drive motor. The drive shaft, in its hollow shaft configuration, can, for example, be the motor shaft.

[0031] However, it is also possible that the drive motor drives the drive shaft indirectly, namely via a gearbox.

[0032] The transmission can, for example, include or be a bevel gear transmission, in particular a bevel gear transmission.

[0033] It is also possible that the transmission includes or is a reduction gear that reduces or increases the speed of the drive motor. The transmission can also be a switchable transmission, where, for example, a first and second gear ratio can be selected. For instance, the transmission is a multi-speed transmission, specifically a two-speed transmission.

[0034] The transmission may include or be a planetary gear system.

[0035] Preferably, the gearbox is switchable with respect to its direction of rotation. For example, the gearbox can be switched in opposite directions of rotation, so that the drive shaft can be driven in different directions by the drive motor, even with the same motor rotation direction. The gearbox thus reverses the direction of rotation of the tool shaft from the first direction to the second direction and vice versa.

[0036] It is preferred that the drive shaft is located inside the drive motor. Even in this configuration, it is conceivable that the eccentric gear and / or a transmission gear are located inside the drive motor, and thus the drive motor drives the drive shaft via a gearbox using its motor shaft.

[0037] It is particularly advantageous if the drive shaft is formed by a motor shaft of the drive motor. For example, a laminated core can be arranged on the outer circumference of the drive shaft.

[0038] The drive motor is preferably electrically switchable between a first motor direction of rotation and a second motor direction opposite to the first. When rotating in the first motor direction, the drive motor drives the drive shaft, for example, in such a direction that the tool shaft rotates in the first direction, while when rotating in the second motor direction, the drive motor drives the drive shaft in the opposite direction, so that the tool shaft rotates in the second direction. If the drive motor is a direct drive, the motor direction of rotation is naturally the same as the direction of rotation of the drive shaft. However, with a gearbox connected between the drive motor and the drive shaft, a reversal of the direction of rotation in the drive train between the drive motor and the driven drive shaft of the eccentric gearbox is also possible.

[0039] To switch the motor's direction of rotation between the first and second directions, a control switch with different positions can be provided. For example, a toggle switch could be used. Alternatively, a push-button switch or another type of control switch that must be actuated in a predetermined sequence could be used to change the motor's direction of rotation. For instance, a push-button switch can be toggled by pressing it for varying durations, so that it, or a power supply device, controls the drive motor to rotate in either the first or second direction.

[0040] Such a control switch can simultaneously serve as the on / off switch for turning the drive motor on and off.

[0041] It is preferred that each motor direction of rotation is assigned a separate control switch, so that the operator can specifically set the motor direction of rotation by operating the respective control switch.

[0042] Preferably, the drive motor is an electronically commutated or brushless motor, or a motor without an electromechanical commutator. The hand-held power tool has a power supply device for energizing the brushless or commutatorless drive motor, which allows the direction of rotation of the drive motor to be reversed. The power supply device includes, for example, at least one half-bridge.

[0043] The brushless or electronically commutated drive motor has the advantage of exhibiting identical or essentially identical performance in both directions of rotation. The efficiency of the electronically commutated or brushless motor is also the same or essentially identical in both directions of rotation. Unlike the universal motor or brushed motor, which is also possible in principle and will be discussed later, the electronically commutated / brushless motor has the advantage of being able to operate optimally in opposite directions of rotation. Optimal operating characteristics can be set using suitable software to control the power supply. Among other advantages, the electronically commutated or brushless motor also exhibits no wear on components such as the commutator unit, regardless of the direction of rotation. In contrast to the universal motor, the brushless motor...For example, in machines equipped with a commutator or brushes, the wear of carbon brushes or brushes varies depending on the direction of rotation.

[0044] With brushless motors, changing the direction of rotation is significantly easier. Unlike universal motors or motors with brushes, no complicated electromechanical components are required, such as those that need to be mechanically adjusted by a brush assembly or arrangement of brushes. An electrical switch or sensor, activated by the operator, is sufficient to control the motor's electronics or power supply, thereby changing its direction of rotation.

[0045] However, the principle according to the invention can also be implemented with any other electric drive motor, for example a so-called universal motor.

[0046] The drive motor could also be a pneumatic or compressed air motor. In this case, the hand-held power tool advantageously features a suitable valve arrangement for adjusting the appropriate supply of compressed air.

[0047] The machine housing advantageously features a handle for gripping by an operator. However, it is also possible for a handle element to protrude from the machine housing, in particular a rod-shaped handle element connected to the machine housing via a joint. For example, the hand-held power tool could be a ceiling or wall sander.

[0048] Preferably, the drive motor is arranged in or on the machine housing. The eccentric gearbox can have a gearbox housing on which at least one freewheel device is supported. However, it is also possible that the machine housing, in particular a drive section of the machine housing, forms a gearbox housing for the eccentric gearbox.

[0049] A preferred concept provides that, on the one hand, the forced rotation guide and / or the freewheel device and, on the other hand, the tool holder are arranged on opposite sides of the machine housing, for example, on a top and a bottom. In any case, it is advantageous if the forced rotation guide and / or the freewheel device are arranged in a protected area of ​​the housing and away from the tool holder and thus the disc tool, so that the effects of dust, dirt, or the like are minimized.

[0050] It is advantageous if the forced rotation guide or the freewheel device, or both, are arranged far away from the tool holder within the machine housing. One advantageous concept provides that the forced rotation guide and / or the freewheel device are arranged at an end region of the tool shaft opposite the tool holder or the disc tool, or on a wall region or upper region of the machine housing facing away from the tool holder. For example, it is provided that the freewheel device and / or the forced rotation guide are arranged below an upper cover wall of the machine housing.

[0051] An advantageous ventilation concept can be designed as follows. A fan wheel, which is driven directly or indirectly by the drive motor, or can also be driven by a separate drive, is expediently arranged between the tool holder and one or more of the following components: drive motor and / or forced rotation guide and / or freewheel device. For example, the following series arrangement is provided with respect to a longitudinal axis of the tool shaft and / or drive shaft: forced rotation guide and freewheel device, drive motor, fan wheel, tool holder.

[0052] A suitable arrangement provides that an airflow generated by the fan wheel, for example, first flows through the drive motor before it flows out of the housing or cools the forced rotation guide or the freewheel or both of them on the outflow side.

[0053] A preferred cooling concept involves a cooling airflow through an air guide arrangement of the hand-held machine tool, directed towards the tool holder at the forced rotation guide, the freewheeling device, the drive motor, or combinations thereof. The cooling airflow is drawn in away from the tool holder and thus from the disc tool, where it is contaminated with relatively little or no dust.

[0054] It is advantageous for the machine housing of the hand-held power tool to have at least one inlet opening in an area facing away from the tool holder, for example, on a handle section. Cooling air flows into the machine housing through this inlet opening, for example, a suitable grille, and flows past one or more of the components described below, namely the forced rotation guide, the freewheel mechanism, and the drive motor. The cooling air then preferably flows out through one or more outlet openings in the machine housing. However, it is also possible for the cooling air to flow out completely or partially in the area of ​​the disc tool or the tool holder.It is preferred if the cooling air or cooling airflow exits the machine housing in the direction of work, either at the front or towards the front, so that the cooling airflow can flow into an area of ​​the workpiece located in front of the plate tool or tool holder in the direction of work, for example to blow away dust.

[0055] It is further advantageous if, particularly within the machine housing, a partition is arranged between the tool holder and the forced rotation guide and / or the freewheel mechanism and / or the drive motor, isolating the forced rotation guide, the freewheel mechanism, or the drive motor, or several of them, from a dust-laden area of ​​the hand-held power tool. The dust is generated by the disc tool during operation of the hand-held power tool, for example, when grinding a workpiece. The partition effectively acts as a bulkhead or isolation wall.

[0056] The partition can be formed or provided, for example, wholly or partially by a fan wheel. The fan wheel is preferably arranged close to the tool holder. The fan wheel can, for example, form a kind of base of the machine housing and thus a separating plane between the tool holder and the drive components, in particular the drive motor, the eccentric gear, the forced rotation guide, or the like.

[0057] It is advantageous to provide a sealing arrangement, in particular a labyrinth seal, between the fan wheel and the machine housing.

[0058] A preferred concept involves the cooling airflow being drawn past the drive components, particularly the drive motor and / or the forced rotation guide and / or the freewheel mechanism, by the fan wheel, and then expelled from the machine housing in an area close to the tool holder or the disc tool. The fan wheel itself forms a partition or separating it from a dusty area within the hand-held power tool, where the tool holder or disc tool is located. Dusty air from this dusty area flows, for example, through a dust outlet or suction port. A vacuum cleaner can conveniently be connected to the dust outlet.

[0059] Of course, it is possible that the hand-held machine tool may have a blower or similar other means for generating a dust air stream or for conveying dust-laden air away from the working area of ​​the disc tool.

[0060] It is further advantageous if the forced rotation guide and / or the freewheel device are housed in a protective enclosure or gearbox housing. The enclosure or gearbox housing is expediently a housing completely separate from the machine housing. However, it is also possible for the enclosure or gearbox housing to be at least partially formed by the machine housing, for example, by an outer wall. The enclosure of the gearbox housing expediently has an opening that is sealed by a bearing. This opening serves, for example, to accommodate the drive shaft, the hollow shaft, the motor shaft, or the tool shaft, with the respective shaft being expediently rotatably mounted relative to the gearbox or enclosure housing by the bearing.

[0061] An embodiment of the invention is explained below with reference to the drawing. The drawing shows: Figure 1 is a perspective oblique view of a hand-held machine tool, Figure 2 is a cross-section through a front section of the hand-held machine tool according to Figure 1 , for example along a section line AA in Figure 1 Figure 3 shows a side view of the motor housing and a freewheel arrangement of a variant of the hand-held machine tool according to the preceding figures, of which Figure 4 shows a cross-sectional view along a section line BB. Figure 3 Figure 5 shows a section approximately along a section line C, C in Figure 3 by a freewheel arrangement of the gearbox in a neutral position, Figure 6 the freewheel arrangement according to Figure 5 in a locked position, Figure 7 the freewheel arrangement according to Figure 5 in a free-running position and Figure 8 a schematic further embodiment of the invention in a cross-sectional view.

[0062] A hand-held power tool shown in the drawing is preferably suitable for grinding and / or polishing surfaces. For example, the hand-held power tool is a grinding machine 10.

[0063] The grinding machine 10 has a machine housing 11 which can be conveniently gripped by an operator at a handle section 12. The handle section 12 extends from a drive section 13. A disc tool 14, for example a grinding disc 15, is arranged on the drive section 13. The grinding disc 15 can have an integral abrasive or a removable abrasive 16 arranged on its underside. A top surface 17 of the grinding disc 15 faces the machine housing 11.

[0064] The grinding disc 15 or the disc tool 14 is located essentially below a cover 18 of the grinding machine 10, and is thus covered from above. The cover 18 includes an elastic seal 19, for example a sealing sleeve, which rests against the upper surface 17 of the disc tool 14. The cover 18 is therefore essentially dustproof above or on the grinding disc 15, so that, for example, dust can be extracted from a working area of ​​the grinding disc 15, i.e., in the area of ​​the abrasive 16, through a suction channel 21 extending below the handle section 12. The suction channel 21 terminates in a suction port 22, to which, for example, a vacuum cleaner hose can be connected.

[0065] On the side of the drive section 13 facing the handle section 12, a switch 23 is advantageously located, which can be used to switch the grinding machine 10 on or off. For example, the switch 23 is a push-button switch. The switch 23 can be used to switch on or off a power supply unit 25, which serves to supply power to a drive motor 30. A direction switch 24 can be used to change the direction of rotation of the drive motor 30. The power supply unit 25 is responsible for supplying power to the drive motor 30 in the direction of rotation set by the direction switch 24.

[0066] The power supply unit 25 comprises, for example, a circuit with half-bridges, which is known per se. The drive motor 30 is advantageously a brushless drive motor, in particular a commutatorless or electronically commutated drive motor. However, the drive motor 30 could also be a so-called universal motor, have a commutator, or the like. Furthermore, a compressed air motor or pneumatic motor can also be used as the drive motor. In any case, it is advantageous if the direction of rotation of the drive motor 30 can be switched, for example, by applying appropriate current via the power supply unit 25. With a pneumatic motor or compressed air motor, the direction of rotation can be switched by applying appropriate compressed air.For example, in a drive motor having a commutator or brush assembly, the brush assembly or commutator is adjustable to set the direction of rotation of the drive motor.

[0067] The drive motor 30 has a stator 31 in the interior of which a rotor 32 is rotatably mounted. The drive motor 30 also has an excitation coil assembly 33, which is energized by the current supply device 25. The excitation coil assembly 33 is arranged on a laminated core 34, which enables optimal magnetic flux.

[0068] The rotor 32 is arranged on a drive shaft 35, i.e., a motor shaft. The drive motor 30 is a direct drive. However, this should not be interpreted to mean that a drive concept with a transmission gearbox, for example a bevel gear gearbox and / or a speed-changing gearbox (transmission gearbox) or a gearbox in which the direction of rotation of an output of the gearbox can be switched, is not within the scope of the invention. This will be discussed further in connection with Figure 8 clearly.

[0069] The drive shaft 35 is designed as a hollow shaft 36. The drive shaft 35 is rotatably mounted on bearings 37 and 38 relative to the machine housing 11. The bearings 37 and 38 are longitudinally spaced with respect to an axis of rotation. D, around which the drive shaft 35 rotates.

[0070] The bearings 37, 38 are arranged, for example, on bearing receptacles 46, 47 of a stator body 45 of the drive motor 30. A retaining projection 48, for example, extends in front of the stator body 45 and carries a retaining element 70.

[0071] The drive motor 30 has a fan wheel 39 which is non-rotatably connected to the drive shaft 35. For example, the fan wheel 39 is located next to the lower bearing 38 or at the longitudinal end region of the drive shaft 35 associated with the plate tool 14.

[0072] The hollow shaft 36 has an interior H in which a tool shaft 50 is rotatably mounted. A tool holder 51 for the disc tool 14 is provided at one longitudinal end 52a of the tool shaft 50. The longitudinal end 52a projects in front of the drive shaft 35. The tool holder 51 has, for example, bayonet contours and / or a screw thread and / or a plug-in fitting or similar other retaining means for holding a disc tool. For example, the disc tool 14 is fastened to the tool shaft 50 by means of a screw 53.

[0073] The tool shaft 50 is rotatably mounted on the drive shaft at tool shaft bearings 42, 44 which are spaced apart from each other with respect to the drive axis D. For example, the tool shaft bearings 42, 44 are provided on bearing receptacles 41, 43 in the interior H of the hollow shaft 36 or drive shaft 35.

[0074] The tool shaft bearing 42 is, for example, a ball bearing. The tool shaft bearing 42 is, for example, provided in the region of the longitudinal end 52a.

[0075] In the region of a longitudinal end 52b opposite the longitudinal end 52a, the tool shaft 50 is supported on the drive shaft 35 by means of the tool shaft bearing 44. The tool shaft bearing 44 is, for example, a needle bearing.

[0076] The tool shaft bearings 42, 44 support the tool shaft 50 rotatably with respect to the drive axis D, but not concentrically, rather eccentrically with an eccentricity E. A tool rotation axis W of the tool shaft 50 has the eccentricity E to the drive axis D.

[0077] Due to friction in the tool shaft bearings 42, 44, the tool shaft 50 is driven by the drive shaft 35 when the drive motor 30 sets the drive shaft 35 in rotation. In principle, the tool shaft 50 would reach the rotational speed of the drive shaft 35 unless the disc tool 14 is in contact with a workpiece, which causes the tool shaft to slow down. However, if the disc tool 14 lifts off the workpiece, without the application of a brake to either the disc tool 14 or the tool shaft 50, the rotational speed of the disc tool 14 would increase undesirably. This would cause the disc tool 14 to rotate at high speed when it is repositioned on the workpiece, leading to damage to the workpiece and / or premature wear of the disc tool 14 or the abrasive 16.

[0078] Therefore, braking means in the form of, for example, brake elements 20, which are fixed to the machine housing 11, for example on the cover 18, are provided. The brake elements 20 brake the disc tool 14. The brake elements 20 act, for example, on the top surface 15 of the grinding disc 15 or the disc tool 14. Alternatively or additionally, the elastic seal 19 or the cover 18 on the top surface 17 of the disc tool 14 can also act as a brake.

[0079] The hand-held machine tool 10 also makes it possible to set the tool shaft 50 into controlled eccentric rotational movements or so-called hypercycloidal movements, for which a forced rotation guide 54 is provided. The forced rotation guide 54 comprises rolling elements 55, 57 which are in frictional or positive engagement with each other, so that, for example, the rolling element 55 rolls on the rolling element 57 when the forced rotation guide 54 is active.

[0080] The rolling element 55 is, for example, a gear 56 or a sun gear, which is arranged in an interior space of the rolling element 57 designed as a ring gear 58 and rolls on its inner circumference, for example with interlocking teeth.

[0081] The rolling element 55, for example, is assigned to the tool shaft 50. The rolling element 57, on the other hand, is assigned to the machine housing 11.

[0082] The rolling element 55 is connected to the tool shaft 50 in a rotationally fixed manner.

[0083] The rolling element 57 could, for example, be engaged and disengaged from the rolling element 55 on one side by axial displacement, such as along the drive axis D, or the like. However, a different concept is chosen to effectively deactivate the effect of the rolling element 57 and thus the forced rotation guide 54: To disable the rolling element 57, it is rotatably mounted on the machine housing 11 by means of a bearing 61. If the rolling element 57 can rotate relative to the machine housing 11 by means of the bearing 61, it is driven along by the other rolling element 55, meaning that the rolling element 55 cannot be set into rotation by rolling against the rolling element 57.Thus, the rolling element 55 can rotate freely in the machine housing 11 and also freely with respect to the drive shaft 35 or with respect to the drive axis A, so that the already explained free rotation eccentric mode is present, in which the braking means 20 are effective, but no forced rotation guidance 54 is active.

[0084] It is also possible that the bearing 61 has such a braking torque that it brakes the rolling element 57 to such an extent that the rolling element 57 cannot be carried along completely freely by the rolling element 55, but that a certain torque is transferred from the rolling element 57 to the rolling element 55.

[0085] The bearing 61 is, for example, arranged on the outer circumference of a bearing projection 59 of the rolling element 57 and held by a retaining element 70. The retaining element 70 is fixed in position relative to the machine housing 11. The rolling element 57 or the ring gear 58 is thus rotatably mounted relative to the machine housing 11 by means of the bearing 61. The retaining element 70 has, for example, a retaining projection 71 with which it is connected to the stator body 45, for example by engaging in a receptacle of the stator body 45. A bearing receptacle 72 for the bearing 61 is also provided on the retaining element 70. The retaining element 70 projects radially inward toward the axis of rotation D with a retaining section 73. A retaining segment 74 projects from the retaining section 73.

[0086] A freewheel device 62 of the freewheel assembly 60 is connected to the retaining section 74 and the bearing projection 59 of the ring gear 58 or the rolling element 57. A freewheel part 63 of the freewheel device 62, which is arranged, for example, radially outside, is connected to the bearing projection 59, and a freewheel part 64, which is arranged, for example, radially inside, is connected to the retaining section 74. The freewheel parts 63 and 64 are, for example, components of a freewheel bearing 65. The freewheel parts 63 and 64 cannot rotate relative to each other in a first direction of rotation D1 of the tool shaft 50; they support each other, so that the rolling element 57 is fixed against rotation from the machine housing 11 via the freewheel device 62 and the retaining element 70. Thus, the other rolling element 57, the planet gear, rolls on the inside of the ring gear 58, so that a so-called hypercycloidal movement is forced upon it, i.e. the forced rotation guidance 54 is active.The freewheeling device 62 is in its locked position in this case.

[0087] In a second direction of rotation D2, the freewheel components 63, 64 can rotate relative to each other, so that the rolling element 57 is no longer supported with respect to the machine housing 11 and the rolling element 55 can drive the rolling element 57 along with it, thus allowing it to rotate relatively freely apart from the bearing friction of the freewheel device 62. In this case, the tool shaft 50 is driven freely by the drive shaft 35, but is still braked by the brake elements 20. This has already been explained. The direction of rotation D2 corresponds to the freewheel direction of the freewheel device 62. In the direction of rotation D2, for example, the free rotation eccentric mode is active.

[0088] Therefore, it is possible to switch between the forced rotation eccentric mode and the free rotation eccentric mode by simply reversing the direction of rotation of the drive motor 30.

[0089] For example, to reverse the direction of rotation of the drive motor 30, the direction switch 24 must be actuated. Complex mechanical actuating elements are not necessary; a simple electrical switch is sufficient.

[0090] A symbol F, indicating particularly fine workpiece machining, signals to the operator that the free-rotation eccentric mode can be set in this way. For example, the symbol F is assigned to the direction of rotation D2. The symbol G indicates a coarser workpiece machining operation to the operator, corresponding to the forced-rotation eccentric mode and thus to the direction of rotation D1. The symbols F and G are located, for example, next to the direction switch 24 or assigned to its two switching positions.

[0091] However, it is also possible that each of the two directions of rotation D1 and D2, or the two eccentric modes symbolized by the symbols F and G, is assigned a dedicated actuating switch 24a and 24b. By pressing one of the two actuating switches 24a or 24b, the direction of rotation of the drive motor 30 can be reversed, thus allowing switching between the free-rotation eccentric mode and the forced-rotation eccentric mode with a simple press of a button.

[0092] Furthermore, it is possible to electrically reverse the direction of rotation of the drive motor 30 by means of a specific key sequence, for example by triggering a correspondingly long or short press of the switch 30. For instance, a sequence of two or three short presses of the switch 30 can be assigned to the direction of rotation D1 and thus to the forced rotation eccentric mode, while two or three long presses of the switch 30 with predetermined pauses are assigned to the direction of rotation D2 and thus to the free rotation eccentric mode.

[0093] The freewheeling device 62 and the forced rotation guide 54 are optimally arranged in the hand-held power tool 10 with regard to cooling and minimal interference from dust and other dirt. For example, the freewheeling device 62 and the forced rotation guide 54 are arranged in a region of the machine housing 11 remote from the tool holder 51 and thus from the disc tool 14, preferably below a wall section 11b. The wall section 11b is, for example, located on the top of the housing or at the top of the drive section 13.

[0094] Furthermore, the freewheeling device 62 and the forced rotation guide 54 are arranged in a capsule housing 80. The capsule housing 80 could also be referred to as a gear housing or be a gear housing. The capsule housing 80 has a lower sub-housing 81 and an upper sub-housing 82, which enclose the freewheeling device 62 and the forced rotation guide 54 in a shell-like manner. The part of the capsule housing 80 facing the drive motor 30, or the sub-housing 81, is formed, for example, by the area of ​​the stator body 45 facing away from the excitation coil assembly 33, or by the retaining projection 48. The stator body 45, the retaining projection 48, or the sub-housing 81 are, for example, shell-shaped. The part of the capsule housing 80 or the sub-housing 82 located further away from the drive motor 30 is provided by the retaining body 70, which, in the manner of a cover, forms the retaining projection 48 or 48.The receptacle provided by this covers the freewheeling device 62 and the forced rotation guide 54. The sub-housings 81, 82 are screwed together, for example, by means of one or more screws 83. Preferably, the sub-housings 81, 82 are connected to each other by means of stepped contours 84 and / or labyrinth seals.

[0095] An elastic seal, for example an O-ring, may also be provided between the sub-housings 81 and 82.

[0096] The sub-housing 81 has the bearing receptacle 46 for the bearing 37 of the drive shaft 35 / motor shaft. The bearing 37 simultaneously seals the interior of the capsule housing 80 against the ingress of dust or the like. The bearing 37 forms a seal for the sub-housing 81 and thus for the capsule housing 80.

[0097] As an alternative or supplement to the concept of encapsulating the freewheeling device 82 and the forced rotation guide 54 against dust by means of the capsule housing 80, the dust isolation concept mentioned below is advantageous.

[0098] A lower section of the machine housing 11, facing the plate tool 14 in the drawing, is essentially a dust zone that communicates with the extraction duct 21. The forced rotation guide 54 and the freewheel assembly 60 are not only spatially separated from this area, but also separated by a partition 90.

[0099] The partition 90 is, so to speak, fixed in position with respect to the longitudinal axis of the drive shaft 35, but rotatable. It is provided by a base wall or base wall of the fan wheel 39. A sealing arrangement 91 is provided between an outer circumference of the fan wheel 90 and the machine housing 11. The sealing arrangement 91 includes, for example, a labyrinth seal 92.

[0100] On the side of the fan wheel 90 facing the plate tool 14, an extraction chamber 96 is provided, which communicates with the extraction duct 21. When dusty air S is extracted via the extraction duct 21, the pressure in the extraction chamber 96 is lower than on the side of the fan wheel 39 facing away from the extraction chamber 96 and towards the drive motor 30. This prevents the dusty air S from flowing into the area of ​​the drive motor 30 and ultimately into the area of ​​the forced rotation guide 54 and the freewheel assembly 60. Instead, it flows, if at all, from this "clean" or "fresh air" area towards the extraction chamber 96. As a result, the dust load on the drive motor 30, the forced rotation guide 54, and the freewheel assembly 60 is low.

[0101] The dusty air S can, for example, flow through openings 96 on the sanding disc 15 or disc tool 14 towards the extraction duct 21 in an area 94 between the cover 18 and the sanding disc 15. The cover 18 in turn has openings 95, so that the dusty air S can flow from area 94 into the extraction chamber 96 and ultimately into the extraction duct 21.

[0102] Furthermore, the cooling concept of the hand-held machine tool 10, as explained below, optimally contributes to ensuring that the drive motor 30 and / or the freewheel arrangement 60 and / or the forced rotation guide 54 are optimally cooled and, in particular, are not or only minimally affected by dust.

[0103] A cooling airflow K is generated by the rotation of the fan wheel 39. The cooling airflow K enters the machine housing 11 through inlet openings 97, preferably at the handle section 12 or at least at a section of the machine housing 11 remote from the tool holder 51, flows through the machine housing 11, and exits through outlet openings 98. The outlet openings 98 are preferably located on the drive section 13. Thus, the cooling airflow K preferably flows past the power supply unit 25 to cool it. The cooling airflow K also flows past the freewheel assembly 60 or the freewheel device 62, cooling it as well as the forced rotation guide 54. The cooling airflow K then flows past the drive motor 30 and, in particular, through the excitation coil assembly 33, so that the drive motor 30 is also optimally cooled.The cooling air K, heated in this way, then flows laterally, preferably forwards in the direction of work as in . Figure 1 The cooling air K is drawn in from the machine housing 11, thus originating away from the working area of ​​the disc tool 14, where the dust load is low. The cooling air K then flows towards the disc tool 14, so that it can preferably also help to clear the working area of ​​the disc tool 14, or an area X located forward of the working area of ​​the disc tool 14 in the direction of operation, of, for example, dust or other contaminants.

[0104] During a session in the Figures 3 to 7The hand-held machine tool 110, only partially depicted, contains essentially the same components as the previously described hand-held machine tool 10, in particular the drive motor 30, which is designed as a direct drive. The drive motor 30 is not shown, or only schematically, nor is its drive shaft 35. However, the tool shaft 50, arranged in and driven by the drive shaft 35, is shown. At the upper longitudinal end region of the tool shaft 50, a rolling element 55, designed, for example, as a planetary gear, is provided. This rolling element 55 can, in principle, roll on the rolling element 57, designed as a ring gear 58, when a freewheel arrangement 160 with a freewheel device 162 is in its locked position. The rolling element 55 can engage the rolling element 57 when the freewheel device 162 assumes its freewheel position. The corresponding directions of rotation D1 and D2 of the tool shaft 50 are shown in the Figures 6 and 7 marked.

[0105] The drive motor 30 is, for example, arranged in a motor housing 145, for example in an interior of the motor housing 145 bounded by a circumferential wall 147. A drive shaft or motor shaft of the drive motor 30, not visible in the drawing, is supported, for example, by the bearing 37 already described, which in turn is received in a bearing receptacle 146 of the motor housing 145.

[0106] On the end face or end wall 149a facing the freewheel device 162, the motor housing 145 has a number of several passage openings 149 for cooling air to cool the drive motor 35.

[0107] A retaining projection 148 projects from the end wall or end face 149a, serving to hold a retaining element 170. The retaining element 170 serves, in principle, to hold the freewheel device 160 in a fixed position relative to the machine housing 11 and also to hold a bearing arrangement with a bearing 161 for the rotatable support of the rolling element 57. The retaining element 170 is, for example, provided with a retaining projection 171 that is connected to the retaining projection 148 of the motor housing 145. For example, corresponding plug receptacles and plug projections engage with each other.

[0108] For example, the retaining projection 171 extends from a retaining area 173 in the direction of the axis of rotation D. The retaining area 173 is designed, for example, in the form of an end wall. A bearing receptacle 174 for the bearing 161 is provided on the retaining area 173.

[0109] With respect to the axis of rotation D, a bearing projection 159 extends in front of the rolling elements 57, and the bearing 161 is provided on the radial outer circumference of this projection. The bearing projection 159 is designed, for example, in the form of a pin or a sleeve.

[0110] The bearing 161 is arranged between the holding area 173, in particular the bearing receptacle 174, of the holding body 170, which is stationary with respect to the machine housing 11, and the bearing projection 159.

[0111] Between these two components, the bearing receptacle 174 and the bearing projection 159, the freewheel device 162 is further provided, which has a freewheel part 163, which is connected to the ring gear 58 or the rolling element 57, and a freewheel part 164, which can be fixed in a locking direction relative to the machine housing 11, namely relative to the retaining body 170, in a locking direction corresponding to a direction of rotation D1, while in a direction of rotation D2 a freewheel position is assumed in which the freewheel part 164 and thus the rolling element 57 can rotate relative to the machine housing 11.

[0112] The retaining projection 148 forms a partial housing 181 and the retaining body 170 a partial housing 182 of a capsule housing 180. The capsule housing 180 encloses the forced rotation guide 54. The partial housings 181 and 182 engage with each other via stepped contours or a labyrinth seal 183.

[0113] The bearing 137 seals an opening in the sub-housing 181 through which the drive shaft of the drive motor 30 enters the capsule housing 180, and rotatably supports the drive shaft 35 of the drive motor 30. The bearing 161 is advantageously completely or at least partially covered by a cover wall 184 of the sub-housing 182 or the capsule housing 180.

[0114] The capsule housing 180, and thus the freewheel arrangement 160 and the forced rotation guide 54, are also located in the upper area of ​​the machine housing 11, in any case far away from the plate tool 14. This reduces or prevents the influence or contamination by dust.

[0115] A space 169 is provided between the freewheel part 163 and the freewheel part 164, in which a number of locking elements 165, for example rotary locking elements 165, are movably mounted. The locking elements 165 can move about the axis of rotation D in the space 169, e.g., roll. Advantageously, the locking elements 165 are balls, rollers, or the like.

[0116] In the direction of rotation D2, the freewheeling direction of the freewheel device 162, which corresponds to a free-rotation eccentric mode, the locking elements 165 are received in drive recesses 166 provided on the outer circumference of the freewheel part 163. The drive recesses 166 are deep enough that the locking elements 165 do not cause jamming or blockage of the freewheel parts 163, 164 relative to each other. The distance from the bottom of a respective drive recess 166 to the inner circumference of the freewheel part 164 is greater than the diameter of a locking element 165.

[0117] For example, the drive recesses 166 are provided next to drive projections 166a, which are designed to rotate the locking elements 165 in the direction of rotation D2 and thus ensure that the locking elements 165 enter the drive recesses 166 in the direction of rotation D2. When the locking elements 165 are in the drive recesses 166, they no longer bear against the radial inner circumference of the freewheel part 164, so that the freewheel parts 163, 164 can rotate relative to each other. Therefore, the freewheel part 163, and thus the rolling element 57, is rotatable with respect to the machine housing 11.

[0118] In the direction of rotation D1, however, the blocking elements 165 emerge from the drive recesses 166, for example, by being flung or displaced radially outwards from the drive recesses 166 due to centrifugal forces. They then come into contact with wedge-shaped or blocking ramps 168, which are provided, for example, on the rear sides of the drive projections 166a. The wedge-shaped ramps 168 are so close to the inner circumference of the freewheel part 164 that the blocking elements 165 wedge themselves between the wedge-shaped ramps 168 and the inner circumference of the freewheel part 166, so that the freewheel part 163 is blocked relative to the freewheel part 164, i.e., assumes its locked position. Thus, the ring gear 58 or the rolling element 57 can no longer rotate, which is why the other rolling element 55 rolls on the inner circumference of the rolling element 57, so that ultimately the forced rotation eccentric mode is set.

[0119] In this case too, switching between different eccentric modes is conveniently possible by simply reversing the direction of rotation of the drive motor 35.

[0120] In the schematically indicated embodiment according to Figure 8A drive motor 230, for example a universal motor, a brushless motor, a pneumatic motor, or the like, is arranged in a machine housing 211 and drives a drive shaft 235 via a gear assembly or gearbox 280. The gear assembly includes, for example, a reduction gearbox 281 and / or a switching gearbox 284 for reversing the direction of rotation and / or a right-angle gearbox 287. Thus, a complex drive train is provided, which can, of course, also be designed simply. An integrated gearbox with one or more functions can also be provided, in which, for example, the functions of the transmission gearbox and the right-angle gearbox are realized by a single gearbox unit.

[0121] The output of the drive motor 230 initially drives the transmission gearbox 281. A first gear stage and a second gear stage, representing different gear ratios, can be engaged using an actuating element 282. The actuating element 282 is located, for example, in front of the machine housing 211.

[0122] The output 283 of the transmission 281 drives the direction-of-rotation gearbox or switching gearbox 284. The switching gearbox 284, which can be actuated via an actuating element 285, allows, for example, the direction of rotation of an output 286 of the switching gearbox 284 to be switched. Thus, with the same direction of rotation of the drive motor 230, it is possible to switch between a first and a second direction of rotation of the drive shaft 235.

[0123] The drive motor 230 can, for example, be arranged in a handle section of the machine housing 211, similar to the handle section 12, which is simplified and not shown in the drawing. In any case, the axial direction of the drive motor 230 is perpendicular to the axial direction of the drive shaft 235, for example, at a right angle. The corresponding power transmission between the drive motor 230 and the drive shaft 235 is effected by means of the bevel gear 287, for example, a bevel gear drive. It should be noted here that the bevel gear 287 can also have a gear ratio between the drive motor 230 and its output, which is coupled to the drive shaft 235 or forms the drive shaft 235 itself.

[0124] The drive shaft 235 extends into the interior of a tool shaft 250, which is designed as a hollow shaft 236. The tool shaft 255 is rotatably mounted on the drive shaft 235, for example, by tool shaft bearings 242 and 244 spaced apart from each other with respect to a rotational axis D of the drive shaft 235. At the free end of the tool shaft 250, the previously described disc tool 14, i.e., for example, a grinding disc 15 or polishing disc with a polishing or abrasive 16, is arranged via a tool holder 51 in a manner not shown in detail. In any case, the drive shaft 235 essentially drives the tool shaft 250 via the bearing friction of the tool shaft bearings 242 and 244.

[0125] The rotary axis W of the tool shaft 250 and the rotary axis D of the drive shaft 235 have an eccentricity E, thus realizing an eccentric gear 240. A braking device with brake elements 20, shown schematically, is provided to decelerate the disc tool 14 in a free-rotating eccentric mode.

[0126] To illustrate various versions of the invention, freewheel arrangements 260 and 360 are provided, which are explained below. For example, a rolling element 255 of a forced rotation guide 254 is connected to the tool shaft 250 via a freewheel device 262. The rolling element 255, for example a planetary gear, can roll on the inner circumference of a rolling element 257, designed as a ring gear and stationary with respect to the machine housing 211, when the freewheel device 262 assumes its locking direction. For example, the rolling element 257 is arranged on retaining projections 248, which project radially inward toward the tool shaft 235 from side walls 249 of the machine housing 211.

[0127] The freewheel device 262 is shown only schematically. For example, it has freewheel parts 263 and 264 that cannot rotate relative to each other in the direction of rotation D1, i.e., they are in the locked position, while they can rotate relative to each other in the direction of rotation D2 of the drive shaft 235. The freewheel device 262 is therefore in freewheel mode in the direction of rotation D2. The free-rotation eccentric mode is then engaged. An operator can easily achieve this changeover by switching the gear unit 284 between the two directions of rotation D1 and D2. While a mechanical switch between the eccentric modes is necessary, this offers a significant advantage: the switching device does not need to be located directly in the area of ​​the tool shaft or drive shaft, but can be ergonomically positioned, for example, on a handle, where the direction of rotation can be changed using the actuating element 282.

[0128] In the above embodiments, the ring gear was associated with the machine housing and the planetary gear with the tool shaft. However, a reverse arrangement is also possible, as indicated by a freewheel device 362 of the freewheel assembly 360. In this case, for example, a rolling element 355 associated with the tool shaft 250 is designed as a ring gear, on whose radial inner circumference a rolling element 357, essentially a planetary gear, can roll when the forced rotation guide 354 is active. For example, a freewheel part 363 of the freewheel assembly 362 is connected to the rolling element 355, while a freewheel part 364 is connected to the tool shaft 250.

[0129] The planetary gear or rolling element 357 could, in principle, also be connected to the machine housing 211 via a freewheel device, for example, by means of a freewheel device 462. The freewheel device 462 could, for example, allow free rotation of the rolling element 357 relative to the machine housing 211 in the direction of rotation D2. It is also possible that, in the freewheel position or in the direction of rotation D2, the freewheel device 462, while generally allowing rotation of the rolling element 357 relative to the machine housing, does so with a certain degree of resistance or viscosity. For example, the freewheel device 462 contains a fluid, such as oil, which, in the freewheel position, allows relative rotation of freewheel components of the freewheel device 462, but with a braking torque or rotational resistance.Thus, although the positive guidance 354 is not fully active, it nevertheless imparts a certain hypercycloidal torque to the tool shaft 250 in the freewheel position of the freewheel device 462.

[0130] Advantageously, the rolling element 357 is fixedly arranged on retaining projections 348, which, for example, project from a circumferential wall of the machine housing 211. In the direction of rotation D1, the freewheeling parts 363 and 364 are not rotatable relative to each other, which is why the ring gear or the rolling element 355 rolls on the outer circumference of the rolling element 357. For example, friction surfaces or a toothed connection are provided between the rolling elements 355 and 357. In the direction of rotation D2, however, the freewheeling parts 363 and 364 can rotate relative to each other, which is why the rolling element 355 can remain stationary relative to the machine housing 211. In this case, the tool shaft 250 rotates freely relative to the machine housing 211, apart from being braked by the brake elements 20.

[0131] In the hand-held machine tool 210, a fixed partition 290, penetrated only by the hollow shaft 236, separates an extraction chamber 296, which faces the disc tool 14 and is connected to the extraction duct 21, from a section of the machine housing 211 in which, for example, the drive motor 230 and / or the forced rotation guides 354, 254 and their associated freewheeling devices are located. Extraction from the extraction chamber 296 is possible via the extraction duct 21 and the suction port 22, as described above. Dusty air S can enter the extraction chamber 296 through inlet openings 93 on the disc tool 14.

Claims

1. Hand-held power tool, in particular a grinding machine (10) and / or polishing machine, with an eccentric gear (40) arranged in a machine housing (11) and an electric or pneumatic drive motor (30) for rotary driving of a drive shaft (35) of the eccentric gear (40) about a drive axis (A), wherein the eccentric gear (40) has a tool shaft (50) which is rotatably mounted eccentrically on the drive shaft (35) by means of at least one tool shaft bearing (42, 44) for carrying out eccentric movements and has a tool holder (51) for a disc tool (14), in particular a grinding disc (15) or polishing disc, wherein a forced rotation guide (54) is provided which forces rotational movements of the tool shaft (50) relative to the machine housing (11) in a forced rotation eccentric mode,by one rolling element (55) of the forced rotation guide (54) rolling on another rolling element (57) of the forced rotation guide (54), wherein one rolling element (57) is supported on the machine housing (11) and the other rolling element on the tool shaft (50), characterized by the fact thatA freewheeling device (62) is arranged between at least one of the rolling elements (57) and the tool shaft (50) or the machine housing (11). This freewheeling device supports the at least one rolling element (57) on the machine housing (11) or the tool shaft (50) in a first direction of rotation of the tool shaft (50), corresponding to a locking direction of the freewheeling device (62), with a supporting force suitable for rolling the other rolling element (55), in particular coupling it in a rotationally fixed manner, so that one rolling element (55) supported on the tool shaft (50) can roll on the other rolling element (57) supported on the machine housing (11). In a second direction of rotation of the tool shaft (50), corresponding to a freewheeling direction of the freewheeling device (62), the freewheeling device (62) is rotatably released, so that the tool shaft (50) can rotate relative to each other with respect to the machine housing without relative rotation of the rolling elements (55, 57). (11) is rotatable.

2. Hand-held machine tool according to claim 1, characterized by the fact thatone of the rolling elements (55) is a planet gear and the other rolling element (57) is a ring gear (58) receiving the planet gear, wherein it is advantageously provided that the ring gear (58) is assigned to the machine housing (11) and the planet gear is assigned to the tool shaft (50).

3. Hand-held machine tool according to one of the preceding claims, characterized by the fact that the rolling elements have teeth or are gear elements, or that there is a frictional connection between the rolling elements.

4. Hand-held machine tool according to one of the preceding claims, characterized by the fact that only one of the rolling elements (57) is supported by a freewheel device (62) with respect to the tool shaft (50) or the machine housing (11), or both rolling elements are each supported by a freewheel device (62) with respect to the tool shaft (50) or the machine housing (11).

5. Hand-held machine tool according to one of the preceding claims, characterized by the fact thatthe at least one freewheel device (62) locks or restrains the rolling element (57) supported on it in the locking position with respect to rotation relative to the component supporting the freewheel device (62), the machine housing (11) or the tool shaft (50), and / or the at least one freewheel device (62) forms part of a bearing (65) or is arranged on a bearing with which the rolling element (57) is rotatably mounted relative to the machine housing (11) or the tool shaft (50), wherein it is advantageously provided that the bearing (65) is a rolling bearing, in particular a ball bearing.

6. Hand-held machine tool according to one of the preceding claims, characterized by the fact thatthe tool shaft (50) is eccentrically mounted in the drive shaft (35) and / or that the drive shaft (35) has a hollow shaft (36) or is designed as a hollow shaft (36) in which the tool shaft (50) is arranged, and / or that the tool shaft (50) projects in front of the drive shaft (35) at an area away from the tool holder (51) and carries one of the rolling elements (57).

7. Hand-held machine tool according to one of the preceding claims, characterized by the fact that the drive motor (30) is arranged between the tool holder (51) and at least one of the rolling elements (57) and / or the freewheel device (62) and / or the forced rotation guide (54) and / or that the drive motor (30) is a brushless and / or electronically commutated motor and / or that the drive shaft (35) is arranged in an interior space of the drive motor (30) and / or that the tool shaft (50) and the drive shaft (35) rotate in the same direction.

8. Hand-held machine tool according to one of the preceding claims, characterized by the fact that the drive shaft (35) is formed by a motor shaft of the drive motor (30) and / or the drive motor (30) directly drives the drive shaft (35) or that a transmission (284) which can be switched, in particular with regard to its direction of rotation and / or its transmission ratio, and / or an angle transmission (287) and / or a transmission transmission (281) is arranged between the drive motor (30) and the drive shaft (35).

9. Hand-held machine tool according to one of the preceding claims, characterized by the fact thatthe drive motor (30) is electrically, in particular electronically, switchable between a first motor direction of rotation and a second motor direction of rotation opposite to the first motor direction of rotation, wherein it is advantageously provided that it has a switch (30) to be actuated in a predetermined switching sequence or an operating switch (24) that can be brought into different switching positions or an actuating switch (24a, 24b) each assigned to the first motor direction of rotation and the second motor direction of rotation.

10. Hand-held machine tool according to one of the preceding claims, characterized by the fact thatThe tool shaft (50) is in a free-rotation eccentric mode in the second direction of rotation, in which the tool shaft (50) performs rotational movements due to bearing friction of the at least one tool shaft bearing (42, 44) when the drive shaft (35) rotates and is freely rotatable with respect to the drive axis (A), wherein the hand-held machine tool expediently has braking means for braking the tool shaft (50) or the tool in the free-rotation eccentric mode.

11. Hand-held machine tool according to one of the preceding claims, characterized by the fact thaton the one hand the forced rotation guide (54) and / or the freewheel device (62) and on the other hand the tool holder (51) are arranged on opposite sides, in particular a top and a bottom, of the machine housing (11) and / or that the forced rotation guide (54) and / or the freewheel device (62) are arranged on an end region of the tool shaft (50) opposite the tool holder (51) and / or on a wall region (11b) of the machine housing (11) facing away from the tool holder (51) and / or outside a dust air stream (S) flowing away from the working area of ​​the disc tool (14).

12. Hand-held machine tool according to one of the preceding claims, characterized by the fact thatthe forced rotation guide (54) and / or the freewheel device (62) are arranged in completely or substantially enclosed capsule housings (80), wherein it is advantageously provided that at least one opening of the capsule housing (80) is sealed by a bearing (37) and / or the capsule housing (80) has shell-like partial housings (81, 82) enclosing the forced rotation guide (54) and / or the freewheel device (62).

13. Hand-held machine tool according to one of the preceding claims, characterized by the fact that a fan wheel (39), driven in particular directly or indirectly by the drive motor (30), is arranged between the tool holder (51) and the drive motor (30) and / or between the tool holder (51) and the forced rotation guide and / or between the tool holder (51) and the freewheel device (62).

14. Hand-held machine tool according to one of the preceding claims, characterized by the fact thatA partition (90), in particular located in the machine housing (11), is arranged between the tool holder (51) on the one hand and the forced rotation guide (54) and / or the freewheel device (62) and / or the drive motor (30) on the other hand, which isolates the forced rotation guide (54) or the freewheel device (62) or the drive motor (30) from a dust-laden area or extraction chamber (96) of the hand-held machine tool, wherein the dust is generated by the disc tool (14) during operation of the hand-held machine tool, wherein it is advantageously provided that the partition (90) is at least partially or completely provided or formed by a fan wheel (39) and / or that a seal (92), in particular a labyrinth seal, is provided between an edge region of the fan wheel (39) and the machine housing (11).

15. Hand-held machine tool according to one of the preceding claims, characterized by the fact thatit has an air guidance arrangement for guiding a cooling air flow (K) past the forced rotation guide (54) and / or the freewheel device (62) and / or the drive motor (30) in the direction of the tool holder (51) and / or that the machine housing (11) has at least one inlet opening (97) in an area away from the tool holder (51), in particular on a handle section (12), into which a cooling air flow (K) flows into the machine housing (11) during operation of the hand-held power tool, flows past the forced rotation guide (54) and / or the freewheel device (62) and / or the drive motor (30) and in particular flows out of the machine housing (11) via at least one outlet opening (98) of the machine housing (11).

Images