Electric power tool

Abstract

The invention relates to a power tool (14a), in particular an angle grinder (with power tool), wherein a lubricant for gearbox lubrication is received in a gearbox housing interior (108) of the gearbox housing (52a), wherein the output shaft (12a) has a first end on which an insert tool unit (18a) can be mounted, and a second end, wherein the output shaft (12a) is designed as a hollow spindle having a cavity (115) and a hollow cylinder section (105) at its second end, and wherein an actuator (30a) is arranged rotationally fixed to the gearbox housing (52a) and engages in the hollow cylinder section (105), wherein a gap (110) extending along the axis of rotation (R) is formed between the hollow cylinder section (105) and the actuator (30a), which is connected at its first end (111) to the cavity (115) and at its second end (112) is connected to the gearbox housing interior (108),and wherein a shaft seal (100) is arranged in the gap (110) which prevents lubricant from escaping from the gap (110) towards the first end (111) of the output shaft (12a).

Description

[0001] The invention relates to a power tool, in particular an angle grinder, with a drive motor accommodated in a housing for driving a drive shaft, with a gear housing for accommodating a gear unit, in particular an angle gear, for converting the rotation of the drive shaft into a rotation of an output shaft about a rotation axis of the gear unit, wherein a lubricant for gear lubrication can be accommodated in a gear housing interior of the gear housing, wherein the output shaft has a first end, to which an insert tool unit can be mounted, and a second end, wherein the output shaft is designed as a hollow spindle having a cavity, which has a hollow cylinder section at its second end, and wherein an actuator is arranged rotationally fixed to the gear housing,which engages the hollow cylinder section and serves, in particular, to fix the insert tool unit to the output shaft without tools. Such a power tool is known from WO2018072995A1.

[0002] During operation of such power tools, it has been observed that, due to the rotation of the hollow spindle, the lubricant leaks from the interior of the gearbox housing and enters the hollow space between the actuator and the hollow cylindrical section of the hollow spindle, from where it leaks into the environment. This results in the work area becoming contaminated and, after prolonged use, the gearbox running dry, which typically leads to power tool failure.

[0003] The object of the present invention is therefore to counteract or, if possible, prevent the leakage of lubricant from the interior of the gearbox housing.

[0004] The invention solves this problem by the power tool according to claim 1. Preferred embodiments of the invention are the subject matter of the dependent claims and result from the description of the invention and from the figures.

[0005] A gap is formed between the hollow cylinder section and the actuator, extending along the axis of rotation (R), which is connected at its first end to the hollow space of the hollow spindle and at its second end to the interior of the gearbox housing. This means that there is a connection between the hollow space of the hollow spindle and the interior of the gearbox in the form of a passage, or a through-passage, a gap. The lubricant entering the gap exerts a lubricating effect between the actuator and the hollow spindle, and a shaft seal arranged in the gap also prevents lubricant from escaping from the gap in the direction of the first end. The gap is sealed by a shaft seal, allowing lubricant to enter the area between the actuator and the hollow spindle, with the shaft seal reducing or preventing the loss of lubricant to the environment.In this way, the gearbox remains operational and the reliability of the power tool is increased.

[0006] The shaft seal is preferably designed according to one of the following types of shaft seals: Threaded shaft seal: This type of seal utilizes a thread on the output shaft to create a seal by means of a return flow characteristic. Radial shaft seal: This seal is suitable for sealing the cavity of the rotating output shaft in the radial direction. It consists, in particular, of a sealing lip that sits either directly on the shaft or on an elastic elastomer.

[0007] Axial shaft seal: This seal can be used to prevent the leakage of grease from the gap between the rotating hollow spindle and the actuator in the axial direction.

[0008] Labyrinth seal: This type of seal consists of a series of interlocking rings and / or steps and is used to minimize grease loss through the gap between the rotating output shaft and the actuator.

[0009] Magnetic shaft seal: This type of seal uses magnetic force to achieve a tight seal.

[0010] The shaft seal is preferably a threaded shaft seal. The threaded shaft seal is designed, in particular, to return the lubricant from the gap toward the gearbox housing. The principle is as follows: A lubricant-filled hollow cylindrical section of the hollow spindle, which rotates around the actuator, carries lubricant in the circumferential direction. If there are additional inclined channels (grooves) in the inner wall of the hollow cylindrical section or in the outer wall of the actuator—or in a bushing inserted into the gap—the lubricant carried by the output shaft is deflected along the side walls of these channels. This creates an axial flow component in the channels; in other words, the rotating output shaft conveys fluid, particularly liquid, axially through the gap.

[0011] A groove in a cylinder that runs diagonally to the circumferential direction forms a thread. Whether the thread is in the rotating output shaft, a used Whether the lubricant is in the bushing or in the stationary actuator does not change the principle of lubricant delivery. The "threaded shaft" becomes a seal in that the return flow, which is generated by the rotation of the output shaft relative to the actuator, counteracts a pressure-induced leakage flow through the gap. The delivery effect is influenced by the direction of rotation and the thread pitch α. Preferably, 2° <= α <= 45°, preferably 3° <= α <= 35°, preferably 3° <= α <= 20°, preferably 4° <= α <= 15°, preferably 4° <= α <= 10°.

[0012] Preferably, the actuator engages the hollow cylinder section up to an engagement length. Preferably, the axial length of the threaded portion of the hollow cylinder section, the actuator, or the bushing is less than the engagement length. Preferably, the axial length of the threaded portion of the hollow cylinder section, the actuator, or the bushing is equal to, or substantially equal to, the engagement length. Preferably, the length of the bushing is less than, or preferably equal to, the engagement length. The conveying effect can be configured by the axial length of the threaded portion.

[0013] The thread of the threaded shaft seal is preferably a flat thread. This results in particularly good conveying efficiency. The thread, in particular a flat thread, preferably has a rectangular cross-section. This results in particularly good sealing properties in laminar flow. The flat thread has a flat profile: the height H of the thread in the axial direction is a factor c greater than the depth t of the thread in the radial direction (H = c * t). The factor c can be at least 2, 4, 6, 8 or 10 (H > c * t). The flank angle β of the thread is preferably 0°, whereby the thread flanks are parallel to one another, but it can also be between 0 and 20°.

[0014] The gap depth h remaining between the thread and the actuator or between the thread and the hollow cylinder section is preferably selected to be as small as possible and can be in the range of h = 10...60µm in the radial direction, taking thermal expansion into account.

[0015] The thread, in particular the flat thread, of the threaded shaft seal preferably has only one thread pitch. However, it is also particularly preferred for the thread, in particular the flat thread, to have multiple starts. The thread pitch angle is further preferably in the range of α = 10°...15°...20°. The thread depth t in the radial direction is preferably at least or approximately two or three times as large as the gap width h, so that t / h = 2...2.5...3. The thread preferably has a depth of equal to or less than t = 0.1 mm. The starts and the ridges of the thread are preferably of the same width.

[0016] Preferably, a bushing is arranged in the hollow cylinder section, which bushing is secured in particular against rotation about the axial direction relative to the hollow cylinder section, or which is arranged immovably relative to the hollow cylinder section. Preferably, the bushing is pressed into the hollow cylinder section. Preferably, an internal thread is formed on the cylindrical inner wall of the bushing - however, the thread can also be provided on the actuator if a bushing is present, in which case the bushing preferably has a smooth inner wall. The bushing can be used to limit and define the width of the gap in the radial direction in order to determine the opening cross-section for the passage of the lubricant. The sealing effect can be further adjusted depending on the axial length of the bushing.

[0017] The bushing is preferably made of metal, especially bronze. However, it can also be made of ceramic, plastic, or a composite material.

[0018] Preferably, the bushing has an outer flange adjacent to the second end of the output shaft in the region of the hollow cylinder section. This facilitates the positioning and securing of the bushing in the hollow spindle.

[0019] Preferably, the bushing has a wall thickness between 0.2 mm and 0.8 mm, preferably between 0.3 mm and 0.5 mm.

[0020] Preferably, an internal thread is formed on a cylindrical inner wall of the hollow cylinder section, forming the threaded shaft seal. The opposite wall of the actuator is preferably smooth in this case.

[0021] Preferably, an external thread is formed on a cylindrical outer wall of the actuator, forming the threaded shaft seal. The surface of the opposite wall of the hollow cylinder section is preferably free of grooves or depressions and thus smooth.

[0022] Preferably, the actuator engages the hollow cylinder section up to an engagement length. Preferably, the axial length of the threaded portion of the hollow cylinder section, the actuator, or the bushing is less than the engagement length. Preferably, the axial length of the threaded portion of the hollow cylinder section, the actuator, or the bushing is equal to, or substantially equal to, the engagement length. Preferably, the length of the bushing is less than, or preferably equal to, the engagement length.

[0023] The hollow spindle preferably has a first hollow cylinder section with a first diameter, into which the actuator in particular engages, and concentric with this at least one second hollow cylinder section with a second diameter. The value of the second diameter deviates in particular from the value of the first diameter and is in particular larger than the first diameter, in particular at least twice as large. This allows the locking mechanism of the quick-action clamping device to be accommodated in the hollow spindle. The actuator, which can preferably be moved translationally relative to the gear housing, is in particular an actuating element which can be deflected against a spring force by a manually operable lever element. An eccentric is in particular arranged on the lever element.

[0024] The actuator preferably extends axially through a passage through the gear housing, in particular also through an outer housing of the power tool. A seal, in particular an O-ring element, is provided to seal the passage, in particular to prevent lubricant from escaping there. Between one end face of the hollow cylinder section, in particular, a cover element is provided, which supports the hollow cylinder section axially relative to the gear housing. The cover element preferably presses the seal against the gear housing or a wall section surrounding the passage.

[0025] The hollow spindle is preferably mounted on the gearbox housing by means of a first bearing, and preferably mounted on a bearing plate element or a receiving flange of the bearing plate element by means of a second bearing. The output shaft extends in particular through the bearing plate element and the receiving flange. The first bearing is preferably a needle bearing, which allows for a small component volume. The second bearing element is preferably a ball bearing, a sealed ball bearing. The gearbox housing interior is sealed in particular by the second bearing and in particular partially sealed by the first bearing.

[0026] The power tool preferably has a quick-clamping device designed for tool-free fixation of the insert tool unit to the output shaft. Preferably, the actuator is an actuating element of the quick-clamping device.

[0027] Preferably, the quick-clamping device has at least one clamping unit which, for tool-free fixing of the insert tool unit to the output shaft, has at least one movably mounted clamping element for exerting a clamping force on the insert tool unit in a clamping position of the clamping element, and has at least one operating unit for carrying out a movement of the clamping element into the clamping position and / or into a release position of the clamping element, in which the insert tool unit can be removed from the clamping unit.

[0028] Preferably, the quick-clamping device has at least one decoupling unit which is provided to decouple the operating unit from the clamping unit depending on a rotational speed of the output shaft.

[0029] The power tool is preferably designed as an angle grinder, in particular as an EC mains angle grinder.

[0030] Advantageously, a hook device of a tool holder of the quick-clamping device has a snap mechanism through which an accessory in the form of an insert tool can be picked up by clicking in. The term insert tool can encompass all tools with which it is possible to process or remove a wide variety of materials, e.g., grinding or cutting wheels, brushes, diamond cutting tools, flexible grinding wheels, fan wheels, diamond hole cutters, etc.

[0031] In the following, the invention is explained in more detail using several embodiments shown in the drawings, in which: Fig. 1 shows a side view of a tool according to the invention designed as an angle grinder according to an embodiment. Fig. 2 shows a side cross-sectional view of a partial area of ​​a tool according to the invention designed as an angle grinder according to an embodiment. Fig. 3a shows a detail of the cross-sectional view from Fig. 2Fig. 3b cross-sectional view of the embodiment of the Fig. 2 used bushing with threaded shaft seal.

[0032] In Figure 11 shows a power tool designed as a portable machine tool 14a, with a quick-clamping device 10a, similar to the machine tool shown in WO2018072995A1. The machine tool is shown as an angle grinder. However, it is also possible for the portable machine tool 14a to have a different design, such as a circular saw or grinding machine. The gear housing 52a of the portable machine tool 14a serves to receive and / or mount a gear unit 54a and is preferably made of a metallic material. However, it is also conceivable for the gear housing 52a to be made of another suitable material, such as plastic. The gear unit 54a is designed as an angular gear and includes a rotatingly driven output shaft 12a, to which an insert tool unit 18a can be fixed by means of the quick-clamping device 10a.The portable machine tool 14a contains a hollow spindle as output shaft 12a, in which the quick-action clamping device 10a is located at least partially (see . Figure 2). A protective hood unit 90 can be attached to the gear housing 52a or the receiving flange 92 of a bearing plate in a manner already known, while an auxiliary handle can also be attached to the gear housing 52a in a manner already known. The drive unit 58a of the portable power tool 14a is received and / or mounted in the motor housing 56a. Preferably, the drive unit or the drive motor 58a drives the output shaft 12a in rotation about the rotation axis 48a by means of cooperation with the gear unit 54a. The rotation axis 48a of the output shaft 12a runs at least substantially perpendicular to a drive rotation axis 60a of the drive unit 58a.The drive unit 58a is preferably designed as an electric motor, but may also have another configuration that appears appropriate to a person skilled in the art, such as a combustion drive unit, hybrid drive unit, pneumatic drive unit or the like.

[0033] Figure 2shows a representation of the gear housing 52a and the quick-clamping device 10a of a portable power tool 14a. This quick-clamping device serves to securely fasten the insert tool unit 18a to the rotatably driven output shaft 12a. It consists of at least one clamping unit 16a, which includes a movably mounted clamping element 20a, 22a that exerts a clamping force on the insert tool. The quick-clamping device 10a additionally contains an operating unit 24a, which allows the clamping element 20a, 22a to be moved into the clamping position and / or a release position, whereby the insert tool 18a can be removed from the clamping unit 16a and / or the output shaft 12a.

[0034] The clamping unit 16a includes at least two movably mounted clamping elements 20a and 22a, but it is also possible for it to contain a different number of clamping elements. Both clamping elements 20a and 22a have a similar construction, which is why features described for one of the clamping elements also apply to the other. The clamping elements 20a and 22a are pivotally mounted and have a pivot axis 62a that runs essentially perpendicular to the rotational axis 48a of the output shaft 12a. They serve to fix the insert tool unit 18a in an axial position on the output shaft 12a, particularly in the clamping position. The clamping elements 20a and 22a are connected to the output shaft 12a in a rotationally fixed manner and rotate together with it about the rotational axis 48a.

[0035] The clamping unit 16a has at least one rotary drive element to enable the transmission of torque to the insert tool unit 18a. When the insert tool unit 18a and the clamping unit 16a or the output shaft 12a are arranged in a specific manner, this rotary drive element engages in a receiving recess on the insert tool unit 18a and transmits the torque to a delimiting edge of the insert tool unit 18a. The transmission of torque between the output shaft 12a and the insert tool unit 18a occurs in a known manner by means of a positive connection between the rotary drive element and the insert tool unit 18a. The rotary drive element is non-rotatably attached to the output shaft 12a and can rotate together with it about the rotation axis 48a.

[0036] The operating unit 24a is primarily intended to move the clamping elements 20a and 22a, in particular the two clamping elements 20a and 22a, at least into the position in which the insert tool 18a can be removed from the clamping unit 16a or the output shaft 12a. Alternatively or additionally, it is possible for the operating unit 24a to be used to move the clamping elements 20a and 22a, in particular the two clamping elements 20a and 22a, at least into the clamping position in which the insert tool 18a can be fixed to the output shaft 12a by the clamping unit 16a. The operating unit 24a preferably comprises at least one operating element 66a that can be actuated by a user. The operating element 66a is designed as an operating lever and has a movement axis 68a, in particular a pivot axis, which runs transversely, in particular at least substantially perpendicularly, to the rotation axis 48a of the output shaft 12a.The operating element 66a is preferably pivotally mounted about the movement axis 68a, in particular the pivot axis, and is separated from a rotational movement of the output shaft 12a.

[0037] The operating element 66a includes an eccentric section 70a to actuate an actuating element 30a of the operating unit 24a. The actuating element 30a is movably mounted along the rotational axis 48a, for example, the output shaft 12a or in the gear housing 52a. It is secured against rotation in the gear housing 52a, for example, by at least one lateral flattening that allows axial movement and prevents rotational movement. Ideally, the actuating element 30a has at least one flattening on each of two opposite sides. It is also possible for the actuating element 30a to have an alternative design that appears sensible to an expert, such as a polygonal cross-section or toothing, in order to secure the actuating element 30a against rotation relative to the gear housing 52a. In the area of ​​the actuating element 30a, a sealing element 72a, e.g.A rubber seal is provided to prevent dirt from entering the gear housing 52a and / or the clamping unit 16a. The sealing element 72a is fixedly arranged and bears against the actuating element 30a. Upon movement of the actuating element 30a, the actuating element 30a slides on at least one sealing surface of the sealing element 72a.

[0038] The quick-release clamping device 10a includes at least one decoupling unit 26a, which serves to separate the operating unit 24a from the clamping unit 16a depending on the speed of the output shaft 12a. The decoupling unit 26a is designed such that, upon a change in the speed of the output shaft 12a, a movement occurs between at least a part of the decoupling unit 26a and the actuating element 30a of the operating unit 24a, thereby separating the operating unit 24a from the clamping unit 16a. The decoupling unit 26a includes at least the movably mounted decoupling element 28a, which, upon changes in the speed of the output shaft 12a, can be moved into a decoupling position in which the operating unit 24a is separated from the clamping unit 16a. The decoupling unit 26a is preferably designed as a friction decoupling element.

[0039] The decoupling unit 26a has at least the movably mounted decoupling element 28a, which is movable relative to the output shaft 12a due to a frictional force between the decoupling element 28a and the actuating element 30a of the operating unit 24a. The decoupling unit 26a has at least the movably mounted decoupling element 28a, which is movably mounted in the output shaft 12a along and / or around the rotational axis 48a of the output shaft 12a. The decoupling unit 26a comprises at least the movably mounted decoupling element 28a and at least one decoupling spring element 44a, which applies a spring force to the decoupling element 28a in the direction of the operating unit 24a. The decoupling unit 26a has at least the movably mounted decoupling element 28a and at least one link element for guiding the decoupling element 28a during a relative movement of the decoupling element 28a relative to the output shaft 12a.

[0040] The decoupling element 28a can be brought into contact with the actuating element 30a via a force-locking connection, or it is already in contact via such a connection. The decoupling element 28a is preferably mounted such that it can be moved along the rotational axis 48a, in particular within the output shaft 12a or a transmission element 42a of the clamping unit 16a. It has a conical connection area that at least partially engages in a recess of the actuating element 30a. The frictional effect between the actuating element 30a and the decoupling element 28a depends on the design of the conical connection area and the spring force of the decoupling spring element 44a. The decoupling spring element 44a serves to apply a spring force to the decoupling element 28a in the direction of the actuating element 30a and is arranged in the transmission element 42a, which is designed as a clamping fork.The transmission element 42a is non-rotatably connected to the output shaft 12a, movably mounted within it, and translationally movable along the clamping axis 74a. It can be subjected to a spring force via the tension spring element 76a of the clamping unit 16a along the clamping axis 74a, particularly in the direction of the operating unit 24a.

[0041] The decoupling unit 26a has at least one connecting element 78a, which serves to connect the decoupling element 28a and the transmission element 42a to one another in terms of movement, particularly when the output shaft 12a is rotating slowly or is stationary. The connecting element 78a is designed as a bolt and is fastened to the decoupling element 28a. It can be moved together with the decoupling element 28a and extends into the link element of the decoupling unit 26a. This link element serves as a link guide track and is part of the transmission element 42a. When the output shaft 12a rotates, the decoupling element 28a and the connecting element 78a can rotate relative to the transmission element 42a due to a braking effect by the actuating element 30a.The connecting element 78a can be moved in a guide track designed as a slotted guide track, so that the decoupling element 28a can be moved into a guide recess 80a of the transmission element 42a against the spring force of the decoupling spring element 44a. By actuating the operating element 66a during a rotational movement of the output shaft 12a, a movement of the actuating element 30a and the decoupling element 28a relative to the transmission element 42a can occur. During a rotational movement of the output shaft 12a, it is largely impossible for the transmission element 42a to move due to the action of an operator force via the operating unit 24a and for the clamping element 20a, 22a to be moved from the clamping position to the release position.When the output shaft 12a rotates slowly or is stationary, the axial force exerted by the actuating element 30a on the decoupling element 28a can be transmitted to the transmission element 42a through the interaction of the connecting element 78a and the link element designed as a guide track. The transmission element 42a can be moved by the operating unit 24a against the spring force of the tension spring element 76a. It serves to move the tensioning elements 20a and 22a from their tensioned position to the released position.

[0042] According to the invention, and deviating from the machine tool described in WO2018072995A1, the power tool 14 shown here is a hand-held power tool, with a drive motor 58a accommodated in a housing 52a, 56a for driving a drive shaft 60, with a gear housing 52a for accommodating a gear unit 54a, in particular an angular gear, for converting the rotation of the drive shaft 60 into a rotation of an output shaft 12a about a rotation axis R of the gear unit, wherein a lubricant for gear lubrication can be accommodated in a gear housing interior of the gear housing, wherein the output shaft 12a has a first end, on which an insert tool unit 18a can be mounted, and has a second end, wherein the output shaft 12a is designed as a hollow spindle having a cavity, which has a hollow cylinder section 105 at its second end, and wherein an actuator 30a orPlunger 30a is arranged, here a cylindrical element within the hollow spindle, which engages in the hollow cylinder section 105, wherein a gap 110 extending along the rotational axis R is formed between the hollow cylinder section 105 and the actuator 30a, which gap is connected at its first end 111 to the cavity 115 and at its second end 112 to the gear housing interior 108, and that a shaft seal 100 is arranged in the gap, which counteracts an escape of lubricant from the gap 110 in the direction of the first end 111. .

[0043] The actuator 30a engages the hollow cylinder section 105 up to an engagement length L, here approximately L=5.0 mm. The axial length of the thread-guiding section of the bushing 120 is substantially equal to the engagement length L. The length of the bushing in the axial direction is approximately equal to the engagement length L.

[0044] The actuator 30a extends in the axial direction R at a passage 107 through the gear housing 52a, and also through an outer housing of the power tool 14a. The sealing element 72a, in particular an O-ring element, is provided to seal the passage 107, in particular to prevent lubricant from escaping there. Between an end face 105a of the hollow cylinder section 105 and a gear housing wall 52a', in particular, a cover element 109 is provided, which supports the hollow cylinder section 105 in the axial direction relative to the gear housing 52a. The cover element 109 presses the seal 72a against the gear housing 52a or a wall section 52a' surrounding the passage.

[0045] The hollow spindle 12a is mounted on the gear housing 52a by means of a first bearing, a needle bearing 116, and on a bearing plate element or a receiving flange 92 of the bearing plate element by means of a second bearing, here a ball bearing 117. The output shaft 12a extends through the bearing plate element and the receiving flange 92. The gear housing interior 108 is sealed by the second bearing 117 and partially sealed by the first bearing 116.

[0046] The shaft seal 100 is a threaded shaft seal 100 provided on a bushing 120. The thread is screwed into the inner wall 122 of the bushing 120 as an internal thread 123. It serves to return the lubricant from the gap 110 toward the gearbox housing interior 108. The gap 110, or the gap remaining between the bushing 120 and the actuator 30a, is lubricated by the lubricating grease entering the gap from the gearbox housing interior 108. This return prevents the unwanted escape of lubricating grease; the lubricating grease is forced back by the rotation of the spindle on the outer wall of the actuator 30a toward the end face 105a and into the gearbox housing interior 108.

[0047] At its first end 111, a sealing element, in particular a sealing cap (not shown) surrounding the actuator 30a and / or the decoupling element 28a, can be provided on or in the hollow cylinder section 105, which prevents the penetration of dust into the first end 111 of the gap 110.

[0048] The bushing 120 is pressed into the hollow cylinder section 105 so that it is connected to the hollow spindle 12a in a rotationally fixed and, in particular, axially immovable manner.

[0049] The bushing 120 has an outer flange 121 adjacent to the second end of the output spindle 12a in the region of the hollow cylinder section 105 or its end face 105a. This simplifies the assembly of the bushing in the hollow spindle and ensures a secure fit.

[0050] The bushing 120 has a length X = 5.0 mm in the axial direction, a diameter of D = 6.0 mm, and a wall thickness of about 0.4 mm, as Fig. 3bvisible. The bushing is made of bronze. List of reference symbols

[0051] LInteraction length XLength of 120 DDiameter of 120 10aQuick clamping device 12aOutput shaft 14aMachine tool 16aClamping unit 18aInsert tool unit 20a, 22aClamping element 24aOperating unit 26aDecoupling unit 28aDecoupling element 30aActuating element, actuator 42aTransmission element 44aDecoupling spring element 48aRotational axis 52aGearbox housing 52aGearbox housing wall 54aGearbox unit 56aMotor housing 58aDrive unit, drive motor 60Drive shaft 60aDrive rotational axis 62aPivoting axis 64aRotary driving element 66aOperating element 68aMovement axis 70aEccentric section 72aSealing element 74aClamping axis 76aClamping spring element 78aConnecting element 80aGuide recess 90Protective hood unit 92Mounting flange 100Shaft seal 105Hollow cylinder section 105aEnd face of 105 107Passage 108Gearbox housing interior 109Cover element 110Gap 111First end of 110 112Second end of 110 115Cavity 116Needle bearing 117Ball bearing 120Bushing 121Outer flange of 105 122Inner wall 123Internal thread

Claims

1. An electric power tool (14a), in particular a hand-held electric power tool, with a drive motor (58a) accommodated in a housing (52a, 56a) for driving a drive shaft (60), with a gearbox (52a) for receiving a gear unit (54a), in particular an angular gear, for converting the rotation of the drive shaft (60) into a rotation of an output shaft (12a) about an axis of rotation (R) of the gear unit, wherein a lubricant for lubricating the gear mechanism is receivable in a gear mechanism inner space (108) of the gear mechanism housing (52a), wherein the output shaft (12a) has a first end to which an insert tool unit (18a) is mountable and a second end, wherein the output shaft (12a) is configured as a hollow spindle which has a hollow space (115) and which has a hollow cylindrical section (105) at its second end, and wherein an actuator (30a) is arranged fixedly in terms of rotation with respect to the transmission housing (52a) and engages in the hollow cylinder section (105), characterized in that between a gap (110) is formed the hollow cylinder section (105) and the actuator (30a) the gap extending along the axis of rotation (R) and being connected at its first end (111) to the hollow space (115) and at its second end (112) to the interior (108) of the transmission housing, and that a shaft seal (100) is arranged in the gap (110) and counteracts the lubricant from exiting the gap (110) in the direction of the first end (111) of the output shaft (12a).

2. The electric power tool according to claim 1, characterized in that the shaft seal (100) is a threaded shaft seal that is configured to return the lubricant from the gap (110) in the direction of the gearbox (52a).

3. The electric power tool according to claim 2, characterized in that a bushing (120) is arranged in the hollow cylinder section (105), the bushing being in particular pressed into the hollow cylinder section (105), wherein on the cylindrical inner wall (122) of the bushing is formed an internal thread (123), which forms the threaded shaft seal.

4. The electric power tool according to claim 3, characterized in that the sleeve (120) has an outer flange (121) resting against the second end of the drive shaft (12a), on the end face (105a) of the hollow cylindrical portion (105).

5. The electric power tool according to claim 3 or 4, characterized in that the sleeve (120) has a wall thickness between 0.2 mm and 0.8 mm, preferably between 0.3 mm and 0.5 mm.

6. The electric power tool according to claim 2, characterized in that an internal thread (123) is formed on a cylindrical inner wall (122) of the hollow cylinder portion (105), which internal thread forms the threaded shaft seal (100).

7. The electric power tool according to claim 2, characterized in that an external thread is formed on a cylindrical outer wall of the actuator (30a), forming the threaded shaft seal (100).

8. The electric power tool according to one of the preceding claims, which has a quick-action clamping device (10a) which is set up for a tool-free fixing of the insert tool unit (18a) to the driven shaft (12a).

9. The electric power tool according to claim 1, characterized in that the actuator (30a) is an actuating element (30a) of the quick-action clamping device.

10. The electric power tool according to one of claims 8 and 9, characterized in that the quick-action clamping device (10a) has at least one clamping unit (16a) which, for the tool-free fixing of the insert tool unit (18a) to the driven shaft (12a), has at least one movably mounted clamping element (20a, 22a) for the application of a clamping force to the insert tool unit (18a) in a clamping position of the clamping element (20a, 22a), and at least one operating unit (24a) for carrying out a movement of the clamping element (20a, 22a) into the clamping position and / or into a release position of the clamping element (20a, 22a), in which the insert tool unit (18a) can be removed from the clamping unit (16a).

11. The electric power tool according to claim 10, characterized in that the quick-action clamping device has at least one decoupling unit (26a) which is provided for the purpose of decoupling the operating unit (24a) from the clamping unit (16a) as a function of a rotational speed of the output shaft (12a).

12. The electric power tool according to one of the preceding claims, which is configured as an angle grinder (14a).

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