Power tool

Abstract

The invention relates to an electric power tool (14a), in particular an angle grinder with an electric power tool, wherein a lubricant for lubricating a transmission can be received in a transmission housing interior (108) of a transmission housing (52a), a driven shaft (12a) has a first end on which a plug-in tool unit (18a) can be fitted and is configured as a hollow spindle having a cavity (115), the hollow spindle has a hollow cylinder section (105) on its second end, an actuator (30a) is arranged rotationally fixed to the transmission housing, the actuator is inserted in the hollow cylinder section, a gap (110) extending along an axis of rotation (R) is formed between the hollow cylinder section and the actuator, the gap is connected to the cavity on its first end (111) and to the transmission housing interior on its second end (112), and a shaft seal (100) is arranged in the gap, which inhibits the flow of lubricant out of the gap towards the first end of the driven shaft.

Description

Technical Field

[0001] This invention relates to a power tool, particularly an angle grinder, having a drive motor received in a housing for driving a drive shaft; and a transmission housing for receiving a transmission unit, particularly an angle gear transmission, for converting rotation of the drive shaft into rotation of a driven shaft about the axis of rotation of the transmission unit, wherein a lubricant for lubricating the transmission can be received in the transmission housing cavity, wherein the driven shaft has a first end and a second end, on which an insert tool unit can be fitted, wherein the driven shaft is constructed as a hollow shaft with a cavity, the hollow shaft having a hollow cylindrical section at its second end, and wherein an actuator is arranged anti-rotationally with respect to the transmission housing, the actuator being inserted into the hollow cylindrical section and particularly for tool-less fixing of the insert tool unit to the driven shaft. Background Technology

[0002] This type of power tool is known from WO2018072995A1.

[0003] It has been observed during the operation of these power tools that, due to the rotation of the hollow shaft, lubricant flows out from the inner cavity of the transmission housing, reaches the cavity between the actuator and the hollow cylindrical section of the hollow shaft, and then flows out into the surrounding environment. This causes the work area to become dirty and the transmission to dry out after prolonged use, which often leads to power tool failure. Summary of the Invention

[0004] Therefore, the objective of this invention is to suppress or prevent the lubricant from flowing out of the inner cavity of the transmission housing as much as possible.

[0005] This invention solves this task using a power tool according to the invention. Preferred embodiments of the invention are given in the description and in the accompanying drawings.

[0006] A gap extending along the axis of rotation (R) is formed between the hollow cylindrical section and the actuator. This gap connects to the cavity of the hollow shaft at its first end and to the inner cavity of the transmission housing at its second end. This means that there is a connection, in the form of a channel or through-hole, gap, between the cavity of the hollow shaft and the inner cavity of the transmission. Lubricant entering the gap provides lubrication between the actuator and the hollow shaft, and a shaft seal arranged in the gap further inhibits the outflow of lubricant from the gap toward the first end. By sealing the gap with the shaft seal, lubricant can enter the area between the actuator and the hollow shaft, where the shaft seal reduces or prevents the loss of lubricant to the surrounding environment. In this way, the transmission is kept operationally ready and the reliability of the power tool is improved.

[0007] The shaft seal is preferably constructed according to one of the following types of shaft seals:

[0008] Threaded shaft seals: This type of seal utilizes the threads on the driven shaft to create a seal by means of a return push property.

[0009] Radial shaft seal: This seal is suitable for sealing cavities of rotating driven shafts in the radial direction. It is specifically composed of a sealing lip that either sits directly on the shaft or on a resilient elastomer.

[0010] Axial shaft seal: This seal is used to prevent grease from flowing out axially from the gap between the rotating hollow shaft and the actuator.

[0011] Labyrinth seals: This type of seal consists of a row of interlocking rings and / or steps and can be used to minimize grease loss through the gap between the rotating driven shaft and the actuator.

[0012] Magnetic shaft seals: This type of seal uses magnetic force to achieve a tight seal.

[0013] The preferred shaft seal is a threaded shaft seal. Threaded shaft seals are specifically designed to return lubricant from the gap towards the transmission housing. The principle is as follows: a hollow cylindrical section of a hollow shaft filled with lubricant (which rotates about the actuator) drags the lubricant circumferentially. If there are additional inclined channels (grooves) in the inner wall of the hollow cylindrical section, in the outer wall of the actuator, or in a sleeve inserted into the gap, then the lubricant carried by the driven shaft is deflected on the sidewalls of these channels. This creates an axial flow component in the channels; in other words, the rotating driven shaft pushes fluid, particularly liquid, axially through the gap.

[0014] The grooves in the cylinder, inclined in the circumferential direction, form threads. Whether the threads are located in the rotating driven shaft, in the sleeve into which they are inserted, or in the idle actuator, the principle of lubricant delivery remains unchanged. The "threaded shaft" is used for sealing in such a way that the return flow generated by the rotation of the driven shaft relative to the actuator suppresses leakage flow caused by pressure through the gap. The delivery effect is affected 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°.

[0015] The actuator is preferably inserted into the hollow cylindrical section up to the insertion length. Preferably, the axial length of the threaded guide section of the hollow cylindrical section, the actuator, or the sleeve is less than the insertion length. Preferably, the axial length of the threaded guide section of the hollow cylindrical section, the actuator, or the sleeve is equal to or substantially equal to the insertion length. Preferably, the length of the sleeve is less than or preferably equal to the insertion length. The pushing effect can be shaped by the axial length of the threaded guide section.

[0016] The preferred thread for the threaded shaft seal is a right-angle thread (Flachgewinde, square thread, rectangular thread). This results in particularly good pushing efficiency. Preferred threads, especially right-angle threads, have a rectangular cross-section (Gangquerschnitt). This provides particularly good sealing performance in laminar flow. Right-angle threads have a right-angled shape: the axial height H of the thread is greater than the radial depth t by a factor c (H = c * t). The factor c can be at least 2, 4, 6, 8, or 10 (H > c * t). The thread section angle β is preferably 0°, thus ensuring that the thread sections are parallel to each other, but the thread section angle can also be between 0 and 20°.

[0017] The clearance depth h between the thread and the actuator or between the thread and the hollow cylindrical section is preferably chosen to be as small as possible and, taking thermal expansion into account, can be in the range of h = 10...60 μm in the radial direction.

[0018] The threads of the preferred threaded shaft seal, especially right-angle threads, have only one thread line. However, it is particularly preferred that the threads, especially right-angle threads, are multi-threaded. 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 about two or three times the clearance width h, thus t / h = 2...2.5...3. Preferably, the thread has a depth equal to or less than t = 0.1 mm. The thread head (Gänge) and thread dam (Dämme) are preferably of the same width.

[0019] Preferably, a sleeve is arranged within the hollow cylindrical section, the sleeve being fixed relative to the hollow cylindrical section to prevent rotation about the axial direction, or in other words, the sleeve is arranged to be immovable relative to the hollow cylindrical section. Preferably, the sleeve is inserted into the hollow cylindrical section. Preferably, internal threads are formed on the cylindrical inner wall of the sleeve – however, in the case of existing sleeves, the threads can also be provided on the actuator, in which case the sleeve preferably has a smooth inner wall. The sleeve can limit and define the gap width in the radial direction, so that the opening cross-section for lubricant passage is determined in this way. Depending on the axial length of the sleeve, the sealing effect can be further coordinated.

[0020] The sleeve is preferably made of metal, especially bronze. However, the sleeve may also be made of ceramic, plastic or connecting material, or may be composed of these materials.

[0021] The preferred sleeve has an outer flange that abuts against the second end of the driven shaft in the region of the hollow cylindrical section. This facilitates the positioning and fixation of the sleeve within the hollow shaft.

[0022] The preferred sleeve has a wall thickness between 0.2 mm and 0.8 mm, preferably between 0.3 mm and 0.5 mm.

[0023] Preferably, an internal thread is constructed on the cylindrical inner wall of the hollow cylindrical section, forming a threaded shaft seal. The opposite wall of the actuator is preferably smooth in this case.

[0024] Preferably, external threads are constructed on the cylindrical outer wall of the actuator, forming a threaded shaft seal. In this case, the surfaces of the opposite walls of the hollow cylindrical section preferably do not have grooves or recesses and are therefore constructed to be smooth.

[0025] Preferably, the actuator is engaged in the hollow cylindrical section up to the engagement length. Preferably, the axial length of the threaded guide section of the hollow cylindrical section, the actuator, or the sleeve is less than the engagement length. Preferably, the axial length of the threaded guide section of the hollow cylindrical section, the actuator, or the sleeve is equal to or substantially equal to the engagement length. Preferably, the length of the sleeve is less than or preferably equal to the engagement length.

[0026] The preferred hollow shaft comprises: a first hollow cylindrical section having a first diameter, in particular an actuator being fitted into the first hollow cylindrical section, and at least one second hollow cylindrical section concentric with the first hollow cylindrical section having a second diameter. The value of the second diameter is particularly different from the value of the first diameter and is particularly larger than the first diameter, particularly at least twice the size of the first diameter. This allows the locking mechanism of the quick-clamping device to be received within the hollow shaft. The actuator, particularly the actuating element, is preferably translatably movable relative to the transmission housing, and can be deflected by a manually operable lever element against spring force. An eccentric element is particularly arranged on the lever element.

[0027] The actuator preferably extends axially through the through-hole in the transmission housing, and particularly through the outer housing of the power tool. A seal, particularly an O-ring element, is provided here to seal the through-hole, specifically to prevent lubricant leakage. A cover element, particularly between the top surface of the hollow cylindrical section and the wall of the transmission housing, supports the hollow cylindrical section axially relative to the transmission housing. The cover element preferably presses the seal against the transmission housing or the wall section surrounding the through-hole.

[0028] The hollow shaft is preferably supported on the transmission housing by means of a first bearing, and more preferably supported on a support plate element or a receiving flange of the support plate element by means of a second bearing. The driven shaft extends particularly through the support plate element and the receiving flange. The first bearing is preferably a needle roller bearing, which allows for a very small component volume. The second bearing element is preferably a ball bearing, a sealed ball bearing. The cavity inside the transmission housing is sealed particularly by the second bearing and partially sealed particularly by the first bearing.

[0029] Power tools preferably have a quick-clamping device, which is configured to secure the insert tool unit to the driven shaft without tools. The actuator is preferably the operating element of the quick-clamping device.

[0030] The preferred quick clamping device has at least one clamping unit, which has at least one movably supported clamping element for toolless fixing of the insert tool unit to the driven shaft, for applying clamping force to the insert tool unit in the clamping position of the clamping element; and has at least one operating unit for implementing movement of the clamping element to the clamping position and / or to the loosening position of the clamping element, in which the insert tool unit can be removed from the clamping unit.

[0031] The preferred quick clamping device has at least one disengagement unit, which is configured to disengage the operating unit from the clamping unit according to the rotational speed of the driven shaft.

[0032] Preferred power tools are constructed as angle grinders, especially EC-powered angle grinders.

[0033] Advantageously, the hook device of the tool receiving section of the quick-clamping device has a locking mechanism, through which an accessory in the form of an insert tool can be received by locking. The concept of insert tools includes all tools capable of processing or abrading various materials, such as grinding discs or dividing discs, brushes, diamond cutting tools, flexible grinding discs, flipping discs, diamond hole cutters, etc. Attached Figure Description

[0034] The invention is described in more detail below with reference to several embodiments shown in the accompanying drawings, wherein:

[0035] Figure 1 A side view of a tool according to the invention, implemented as an angle grinder according to one embodiment, is shown.

[0036] Figure 2 A side cross-sectional view of a tool according to the invention, implemented as an angle grinder according to one embodiment, is shown.

[0037] Figure 3a It shows Figure 2 A detail of the cross-sectional view.

[0038] Figure 3b It shows in Figure 2 A cross-sectional view of a sleeve with a threaded shaft seal used in the embodiments. Detailed Implementation

[0039] Figure 1 A power tool 14a, implemented as a portable machine tool 14a, is shown, having a quick-clamping device 10a, similar to the machine tool shown in WO2018072995A1. This machine tool is shown as an angle grinder. However, it is also possible that the portable machine tool 14a has other designs, such as being designed as a circular saw or a grinder. The transmission housing 52a of the portable machine tool 14a is used to receive and / or support the transmission unit 54a and is preferably made of a metallic material. However, it is also conceivable that the transmission housing 52a is made of other suitable materials, such as plastic. The transmission unit 54a is implemented as a winkelgetriebe and includes a driven shaft 12a that is driven to rotate, on which an insert tool unit 18a can be fixed by means of the quick-clamping device 10a. The portable machine tool 14a includes a hollow shaft as the driven shaft 12a, and the quick-clamping device 10a is at least partially located in the hollow shaft (see [link to documentation]). Figure 2 The protective cover unit 90 can be fastened to the transmission housing 52a or receiving flange 92 of the bearing plate in a known manner and type, while the additional handle can also be mounted on the transmission housing 52a in a known manner and type. The drive unit 58a of the portable machine tool 14a is received and / or supported in the motor housing 56a. Preferably, the drive unit or drive motor 58a drives the driven shaft 12a to rotate about the rotation axis 48a by means of cooperation with the transmission unit 54a of the driven shaft 12a. The rotation axis 48a of the driven shaft 12a is at least substantially perpendicular to the drive rotation axis 60a of the drive unit 58a. The drive unit 58a is preferably implemented as an electric motor, but may also have other designs that appear reasonable to those skilled in the art, such as a combustion drive unit, a hybrid drive unit, a pneumatic drive unit, or a similar drive unit.

[0040] Figure 2A diagram shows the transmission housing 52a of a portable machine tool 14a and a quick-clamping device 10a. The quick-clamping device is used to reliably secure an insert tool unit 18a to a driven shaft 12a that can be driven to rotate. The quick-clamping device consists of at least one clamping unit 16a, which includes movably supported clamping elements 20a and 22a that apply clamping force to the insert tool. The quick-clamping device 10a also includes an operating unit 24a that can move the clamping elements 20a and 22a to a clamping position and / or a released position, thereby enabling the insert tool 18a to be removed from the clamping unit 16a and / or the driven shaft 12a.

[0041] The clamping unit 16a includes at least two movably supported clamping elements 20a and 22a, but it may also include different numbers of clamping elements. The two clamping elements 20a and 22a have similar constructions, so features described for one clamping element also apply to the other. The clamping elements 20a and 22a are pivotally supported and have a pivot axis 62a, which runs substantially perpendicular to the rotation axis 48a of the driven shaft 12a. The clamping elements are used to secure the insert tool unit 18a in an axial position on the driven shaft 12a, particularly in a clamped position. The clamping elements 20a and 22a are anti-rotationally connected to the driven shaft 12a and rotate together with the driven shaft about the rotation axis 48a.

[0042] The clamping unit 16a has at least one rotary drive element to transmit torque to the insert tool unit 18a. The rotary drive element is engaged in a receiving recess on the insert tool unit 18a in a defined arrangement of the insert tool unit 18a and the clamping unit 16a or the driven shaft 12a, and transmits torque to the restricted edge of the insert tool unit 18a. Torque transmission between the driven shaft 12a and the insert tool unit 18a is carried out in a known manner by means of a form-locking connection between the rotary drive element and the insert tool unit 18a. The rotary drive element is anti-rotationally secured to the driven shaft 12a and can rotate together with the driven shaft about a rotation axis 48a.

[0043] The operating unit 24a is primarily configured to move the clamping elements 20a and 22a, particularly the two clamping elements 20a and 22a, at least to a position where the insert tool 18a can be removed from the clamping unit 16a or the driven shaft 12a. Alternatively or additionally, the operating unit 24a may be primarily configured to move the clamping elements 20a and 22a, particularly the two clamping elements 20a and 22a, at least to a clamping position in which the insert tool 18a can be secured to the driven shaft 12a by the clamping unit 16a. The operating unit 24a preferably includes at least one operating element 66a, which can be operated by a user. The operating element 66a is configured as an operating lever and has a motion axis 68a, particularly a pivot axis, which runs transversely to, and at least substantially perpendicularly to, the rotation axis 48a of the driven shaft 12a. The operating element 66a is preferably pivotally supported about the motion axis 68a, particularly the pivot axis, and is separated from the rotational motion of the driven shaft 12a.

[0044] The operating element 66a includes an eccentric section 70a for actuating the operating element 30a of the operating unit 24a. The operating element 30a is movably supported along, for example, a rotation axis 48a of the driven shaft 12a or within the transmission housing 52a. The operating element is anti-torsionally fixed within the transmission housing 52a, for example by at least one lateral flattened portion, which allows axial movement and prevents rotational movement. Ideally, the operating element 30a has two opposing sides, each having at least one flattened portion. The operating element 30a may also have alternative designs that seem reasonable to those skilled in the art, such as a polygonal cross-section or teeth, for fixing the operating element 30a against torsion relative to the transmission housing 52a. A sealing element 72a, such as a rubber seal, is preferably disposed in the region of the operating element 30a to prevent contaminants from entering the transmission housing 52a and / or the clamping unit 16a. The sealing element 72a is arranged in a fixed position and abuts against the operating element 30a. When the actuating element 30a moves, the actuating element 30a slides on at least one sealing surface of the sealing element 72a.

[0045] The quick-clamping device 10a includes at least one disengagement unit 26a for separating the operating unit 24a from the clamping unit 16a according to the rotational speed of the driven shaft 12a. The disengagement unit 26a is designed such that, upon a change in the rotational speed of the driven shaft 12a, movement occurs between at least a portion of the disengagement unit 26a and the actuating element 30a of the operating unit 24a, thereby separating the operating unit 24a from the clamping unit 16a. The disengagement unit 26a includes at least a movably supported disengagement element 28a, which can engage in a disengagement position upon a change in the rotational speed of the driven shaft 12a, in which the operating unit 24a is separated from the clamping unit 16a. Preferably, the disengagement unit 26a is implemented as a sliding disengagement device.

[0046] The disengagement unit 26a has at least a movably supported disengagement element 28a, which is movable relative to the driven shaft 12a due to friction between the disengagement element 28a and the actuating element 30a of the operating unit 24a. The disengagement unit 26a has at least a movably supported disengagement element 28a, which is movably supported in the driven shaft 12a along and / or about a rotation axis 48a of the driven shaft 12a. The disengagement unit 26a includes at least the movably supported disengagement element 28a and at least one disengagement spring element 44a, which loads the disengagement element 28a toward the operating unit 24a by a spring force. The disengagement unit 26a has at least a movably supported disengagement element 28a and at least one groove element for guiding the disengagement element 28a during relative movement with respect to the driven shaft 12a.

[0047] The disengagement element 28a can be brought into contact with the actuating element 30a via a force-locking connection, or is already in contact via such a connection. The disengagement element 28a is preferably supported such that it is movable along the rotation axis 48a, particularly within the driven shaft 12a or within the transmission element 42a of the clamping unit 16a. The disengagement element has a tapered connection area that is at least partially fitted into a recess in the actuating element 30a. The frictional action between the actuating element 30a and the disengagement element 28a depends on the design of the tapered connection area and the spring force of the disengagement spring element 44a. The disengagement spring element 44a is used to load the disengagement element 28a toward the actuating element 30a with spring force and is arranged in the transmission element 42a, which is implemented as a clamping fork. The transmission element 42a is anti-rotationally connected to the driven shaft 12a, movably supported within the driven shaft, and capable of translational movement along the clamping axis 74a. The transmission element can be loaded with spring force along the clamping axis 74a, particularly toward the operating unit 24a, via the clamping spring element 76a of the clamping unit 16a.

[0048] The disengagement unit 26a has at least one connecting element 78a for kinematically connecting the disengagement element 28a and the transmission element 42a to each other, particularly when the driven shaft 12a rotates slowly or remains stationary. The connecting element 78a is implemented as a bolt and fastened to the disengagement element 28a. The connecting element can move together with the disengagement element 28a and extends into a grooved element of the disengagement unit 26a. The grooved element serves as a guide rail and is part of the transmission element 42a. If the driven shaft 12a rotates, the disengagement element 28a and the connecting element 78a rotate relative to the transmission element 42a due to the braking action of the actuating element 30a. The connecting element 78a can move within the grooved guide rail, thereby enabling the disengagement element 28a to overcome the spring force of the disengagement spring element 44a and move into the guide recess 80a of the transmission element 42a. Movement of the operating element 30a and the disengagement element 28a relative to the transmission element 42a can be achieved by manipulating the operating element 66a during the rotational movement of the driven shaft 12a. During the rotational movement of the driven shaft 12a, movement of the transmission element 42a is virtually impossible due to the operating force via the operating unit 24a, and movement of the clamping elements 20a and 22a from the clamped position to the released position is virtually impossible. If the driven shaft 12a rotates slowly or remains stationary, the axial force applied to the disengagement element 28a by the operating element 30a can be transmitted to the transmission element 42a through the synergistic action of the connecting element 78a and the slide element implemented as a slide rail. The transmission element 42a can move against the spring force of the clamping spring element 76a via the operating unit 24a. The transmission element is used to move the clamping elements 20a and 22a from their clamped position to their released position.

[0049] According to the present invention, and unlike the machine tool described in WO2018072995A1, the machine tool 14 shown herein is a handheld machine tool.

[0050] A drive motor 58a is received in housings 52a and 56a for driving drive shaft 60.

[0051] It has a transmission housing 52a for receiving a transmission unit 54a, particularly an angle gear transmission, which converts the rotation of the drive shaft 60 into the rotation of the driven shaft 12a about the rotation axis R of the transmission unit.

[0052] Specifically, the inner cavity of the transmission housing can receive lubricant used for lubricating the transmission device.

[0053] The driven shaft 12a has a first end and a second end, and an insert tool unit 18a can be mounted on the first end.

[0054] The driven shaft 12a is constructed as a hollow shaft with a cavity, and has a hollow cylindrical section 105 at its second end.

[0055] Furthermore, the actuator 30a or tappet 30a is arranged in a rotationally resistant manner relative to the transmission housing 52a. This is a cylindrical element designed within a hollow shaft, which is embedded in the hollow cylindrical section 105.

[0056] A gap 110 extending along the rotation axis R is formed between the hollow cylindrical section 105 and the actuator 30a. The gap is connected to the cavity 115 at its first end 111 and to the inner cavity 108 of the transmission housing at its second end 112. A shaft seal 100 is arranged in the gap to prevent lubricant from flowing out of the gap 110 toward the first end 111.

[0057] The actuator 30a is inserted into the hollow cylindrical section 105 up to the insertion length L, which is approximately 5.0 mm. The axial length of the threaded guide section of the sleeve 120 is essentially equal to the insertion length L. The sleeve length along the axial direction is approximately equal to the insertion length L.

[0058] The actuator 30a extends axially R through the through-hole 107 passing through the transmission housing 52a and also through the outer housing of the power tool 14a. A sealing element 72a, particularly an O-ring element, is provided here to seal the through-hole 107, specifically to prevent lubricant leakage. A cover element 109 is provided, in particular, between the top surface 105a of the hollow cylindrical section 105 and the wall 52a' of the transmission housing, supporting the hollow cylindrical section 105 axially relative to the transmission housing 52a. The cover element 109 here presses the seal 72a against the transmission housing 52a or the wall section 52a' surrounding the through-hole.

[0059] The hollow shaft 12a is supported on the transmission housing 52a by means of a first bearing, a needle roller bearing 116, and on a support plate element or a receiving flange 92 of the support plate element by means of a second bearing, a ball bearing 117. The driven shaft 12a extends through the support plate element and the receiving flange 92. The inner cavity 108 of the transmission housing is sealed by the second bearing 117 and partially sealed by the first bearing 116.

[0060] The shaft seal 100 is a threaded shaft seal 100, which is disposed on the sleeve 120. The thread here is screwed into the inner wall 122 of the sleeve 120 as an internal thread 123. The thread is used to push back lubricant from the gap 100 toward the inner cavity 108 of the transmission housing. The gap 110, or the gap maintained between the sleeve 120 and the actuator 30a, is lubricated by grease entering the gap from the inner cavity 108 of the transmission housing. Undesirable outflow of grease is prevented by the return push, and the grease is pushed back onto the outer wall of the actuator 30a toward the top face 105a and squeezed back into the inner cavity 108 of the transmission housing by the rotation of the spindle.

[0061] On its first end 111, a sealing element may be provided on or in the hollow cylindrical section 105, in particular a sealing cap (not shown) surrounding the actuator 30a and / or the disengagement element 28a, which prevents dust from entering the first end 111 of the gap 110.

[0062] The sleeve 120 is squeezed into the hollow cylindrical section 105, thereby connecting the sleeve to the hollow spindle 12a in a rotation-resistant and, in particular, axially immovable manner.

[0063] The sleeve 120 has an outer flange 121 that abuts against the second end of the driven shaft 12a in the region of the hollow cylindrical section 105 or its top surface 105a. This simplifies the assembly of the sleeve in the hollow shaft and achieves a tight fit.

[0064] Sleeve 120 here has an axial length X = 5.0 mm, a diameter D = 6.0 mm, and a wall thickness of approximately 0.4 mm, as shown below. Figure 3b It is evident that the sleeve is currently made of bronze.

[0065] List of reference numerals

[0066] L Interlocking Length

[0067] Length of X 120

[0068] Diameter of D 120

[0069] 10a Quick clamping device

[0070] 12a Driven Shaft

[0071] 14a Machine Tool

[0072] 16a Clamping Unit

[0073] 18a Insertable Tool Unit

[0074] 20a, 22a clamping elements

[0075] 24a Operation Unit

[0076] 26a Detachment Unit

[0077] 28a Detachment element

[0078] 30a Control elements, actuators

[0079] 42a Transmission element

[0080] 44a Disengagement from spring element

[0081] 48a Rotation axis

[0082] 52a Transmission device housing

[0083] 52a' Transmission device housing wall

[0084] 54a Transmission Unit

[0085] 56a Motor Housing

[0086] 58a drive unit, drive motor

[0087] 60 drive shaft

[0088] 60a Drive Rotary Axis

[0089] 62a Pivot axis

[0090] 64a Rotating drive element

[0091] 66a Operating element

[0092] 68a Motion axis

[0093] 70a Eccentric section

[0094] 72a Sealing element

[0095] 74a Clamping axis

[0096] 76a Clamping Spring Element

[0097] 78a Connecting element

[0098] 80a Guide notch

[0099] 90 Protective shield unit

[0100] 92 Receiving flange

[0101] 100 Shaft Seal

[0102] 105 Hollow cylindrical section

[0103] 105a 105 top face

[0104] 107 Pass-through part

[0105] 108 Inner cavity of the transmission device housing

[0106] 109 Cover Components

[0107] 110 gap

[0108] The first end of 111 110

[0109] The second end of 112 110

[0110] 115 Cavity

[0111] 116 needle roller bearing

[0112] 117 ball bearing

[0113] 120 sleeve

[0114] 121 105 outer flange

[0115] 122 Inner Wall

[0116] 123 Internal thread.

Claims

1. A power tool (14a). It has a drive motor (58a) received in a housing (52a, 56a) for driving a drive shaft (60). It has a transmission housing (52a) for receiving a transmission unit (54a) for converting the rotation of the drive shaft (60) into the rotation of the driven shaft (12a) about the rotation axis (R) of the transmission unit. in, The transmission housing cavity (108) of the transmission housing (52a) can receive lubricant for lubricating the transmission device. The driven shaft (12a) has a first end and a second end, and an insert tool unit (18a) can be mounted on the first end. The driven shaft (12a) is constructed as a hollow shaft with a cavity (115) and a hollow cylindrical section (105) at its second end. Furthermore, an actuator (30a) is arranged anti-rotationally with respect to the housing (52a) of the transmission device, and the actuator is embedded in the hollow cylindrical section (105). Its features are, A gap (110) extending along the axis of rotation (R) is formed between the hollow cylindrical section (105) and the actuator (30a), the gap connecting to the cavity (115) at its first end (111) and to the inner cavity (108) of the transmission housing at its second end (112). A shaft seal (100) is arranged in the gap (110) to prevent the lubricant from flowing out of the gap (110) toward the first end (111) of the driven shaft (12a).

2. The power tool according to claim 1, characterized in that, The power tool (14a) is a handheld power tool.

3. The power tool according to claim 1, characterized in that, The transmission unit (54a) is an angle gear transmission device.

4. The power tool according to claim 1, characterized in that, The shaft seal (100) is a threaded shaft seal configured to push the lubricant back from the gap (110) toward the transmission housing (52a).

5. The power tool according to claim 4, characterized in that, A sleeve (120) is arranged in the hollow cylindrical section (105).

6. The power tool according to claim 5, characterized in that, The sleeve (120) is inserted into the hollow cylindrical section (105), and an internal thread (123) is formed on the cylindrical inner wall (122) of the hollow cylindrical section, the internal thread forming the threaded shaft seal.

7. The power tool according to claim 5, characterized in that, The sleeve (120) has an outer flange (121) on the top surface (105a) of the hollow cylindrical section (105) that abuts against the second end of the driven shaft (12a).

8. The power tool according to claim 5, characterized in that, The sleeve (120) has a wall thickness between 0.2 mm and 0.8 mm.

9. The power tool according to claim 5, characterized in that, The sleeve (120) has a wall thickness between 0.3 mm and 0.5 mm.

10. The power tool according to claim 4, characterized in that, An internal thread (123) is constructed on the inner wall (122) of the hollow cylindrical section (105), the internal thread forming the threaded shaft seal (100).

11. The power tool according to claim 4, characterized in that, An external thread is constructed on the cylindrical outer wall of the actuator (30a), the external thread forming the threaded shaft seal (100).

12. The power tool according to any one of claims 1 to 11, the power tool having a quick clamping device (10a) configured to secure the insert tool unit (18a) toolless onto the driven shaft (12a).

13. The power tool according to claim 12, characterized in that, The actuator (30a) is the operating element (30a) of the quick clamping device (10a).

14. The power tool according to claim 12, characterized in that, The quick clamping device (10a) has at least one clamping unit (16a) for toolless fixing of the insert tool unit (18a) to the driven shaft (12a), having at least one movably supported clamping element (20a, 22a) for applying clamping force to the insert tool unit (18a) in the clamping position of the clamping element (20a, 22a), and having at least one operating unit (24a) for implementing movement of the clamping element (20a, 22a) to the clamping position and / or to the loosening position of the clamping element (20a, 22a), in which the insert tool unit (18a) can be removed from the clamping unit (16a).

15. The power tool according to claim 14, characterized in that, The quick clamping device has at least one disengagement unit (26a) configured to disengage the operating unit (24a) from the clamping unit (16a) according to the rotational speed of the driven shaft (12a).

16. The power tool according to any one of claims 1 to 11, wherein the power tool is configured as an angle grinder (14a).

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