DE2655899A1 - CRAFT MACHINE - Google Patents

Description

R. 3C-.

State of the art

The invention is based on a hand machine tool according to the preamble of the main claim. In the case of hand machine tools that have been customary up to now In this way, the axial forces are supported undamped, which results in increased stress on the wrist and the arm of the operator working with the hand machine tool affects.

Advantages of the invention

The hand machine tool according to the invention with the characterizing features of the main claim has the advantage that the support of the axial forces is dampened. This results in minimal noise development during hammer drilling in particular achieved by the so-called B-strokes. (The rebound of the tool or the Drilling spindle on the handheld power tool.) In addition, the handheld power tool according to the invention is characterized by a simple, less prone to failure and cheap construction. Assembly and disassembly of the hand machine tool are in particular very workshop-friendly due to the drill spindle construction according to the invention; Ultimately, it is the sealing of the interior the hand tool is designed to be safe and durable.

The measures listed in the subclaims are advantageous developments and improvements of the main claim specified hand tool possible.

drawing

An embodiment of the invention is shown in the drawing using several figures and in the following

SQ982S / 0042

AV

Description explained in more detail. It shows Figure la a hammer drill in a reduced view, Figure Ib the hammer drill in partial longitudinal section, FIG. 2 shows a cross section along II-II of FIG. 1, FIG. 3 shows a cross section along III-III of FIG. 1 and FIG a partial section along IV-IV of FIG. 1.

Description of the invention

In the drawing, a handheld power tool referred to in more detail as a hammer drill is shown. The hammer drill 1 has a housing consisting essentially of three parts: A housing middle part 2 which is closed on the front side by a housing cover 3 and on the rear side by a rear housing part 5 provided with an integrally formed spade handle 4. All housing parts 2, 3, 5 are made of impact-resistant plastic. In the spade handle 4, a switch provided with a pusher 6 is installed, via which the hand-held power tool can be put into operation. At the lower end of the spade handle η, a power supply cable 7 is inserted through an elastic grommet. At the front end facing away from the spade handle 4, a tool holder 8 is arranged on the hammer drill 1, which tool holder 8 is used to hold tools, not shown in detail, such as drills or chisels.

In the lower area of the housing middle part 2, an electric motor 9 - here a universal motor - is arranged, the one rotor 10 has, which in a known manner on a drive shaft 13 of the electric motor supported on both sides in roller bearings 11, 12 is arranged. The front roller bearing 11 - here a deep groove ball bearing - sits with its inner ring with a press fit the drive shaft 13 and with its outer ring in a rubber bushing 14, which in turn is in a bearing extension 15 of the front Housing cover 3 is held. The bearing bush 14 is braced in such a way that the drive shaft 13 exerts a force in the direction of

009825/0042

the rear roller bearing 12, also designed as a deep groove ball bearing, experiences. The force is greater than all forces that occur in the drive shaft 13 in any operating state of the hammer drill and counteract this force. Due to its softness, the rubber bushing Ik - it is made of a material of high heat resistance and good compression set behavior - is able to absorb relatively large tolerances that may arise in plastic parts in such a way that only a small change in the axial tensioning force on the rotor 10 occurs. Axial misalignment caused by manufacturing tolerances or dimensional changes as a result of heating or creeping of the plastic parts, for example, can easily be compensated for. On the side facing the rotor 10, a fan wheel 16 accommodated in the housing cover 3 sits on the drive shaft 13. On the side facing away from the roller bearing 11, a commutator 17 connects to the fan wheel 16 on the drive shaft 13.

Between the housing middle part 2, which represents the motor housing, and the housing cover 3 adjusted by a fitting 18 in the housing middle section 2, a brush holder plate 19 is arranged, whose side facing away from the rotor is designed as an air guide disk 20 for the fan. The brush holder plate 19 has two diagonally opposite quiver-shaped brush guides 21 (FIG. 2) in which carbon brushes 2k are guided. Furthermore, threads 22 are arranged in the brush holding plate 19, into which screws 25 are screwed. The screws 25 see cover 26 made of plastic with which the rear, outwardly opening ends of the brush guides 21 are closed. Furthermore, threaded inserts 23 for the cable connections assigned to the carbon brushes 2k are arranged in the brush holding plate 19 near the brush guides 21. The parts of the brush holding plate 19 carrying the thread 22 are used as holding extensions 27 for the laminated stator 28 of the electrical

80982670042

engine designed (Figure 4). As can be seen particularly well in FIG. 3, the stator 28 is in fact pushed into four correspondingly configured guide rails 29 of the housing middle part 2 serving as the motor housing. Slipping out of the stator 28 from the innermost position shown in FIG. 1 is thus reliably prevented by the holding projections 27, which can also be provided with rubber buffers 30 on their end face facing the stator 28.

On the side protruding from the roller bearing 12 from the stator 28, the drive shaft 13 is pierced by a lip sealing ring 31 the wall 32 of the middle part of the housing, which delimits the interior of the motor, is sealed. The drive shaft 13 - it has one here hardened, ground steel surface - sits with a sliding fit in the hardened and ground bore of the inner ring of the Rolling bearing 12. As a result, on the one hand, the above-described axial bracing of the two rolling bearings 11, 12 against one another enables and on the other hand a convenient removal and installation of the rotor 10 in the hammer drill. Both mechanically and Highly thermally stressed roller bearing 12 sits with its outer ring with a press fit in a bearing block 33 made of cast aluminum and is of existing in the gear room 34 of the hammer Lubricating oil lubricated and cooled. In this way, the bleeding of the roller bearing 12 as well as the rolling out of the bearing seat surely prevented the collapse of several parts. screwed aluminum bearing back is especially good for discharging the heat generated *

The end of the drive shaft 13 which is supported in the roller bearing 12 ″ carries a motor pinion 35. The! orienting: of the roller bearing 12 is supported in the axial direction at = a press-fit attf of the drive shaft 13 attached: Änschiagriiig 36- ab-. The motor pinion 35 is overdriving a toothing ^ 3T an intermediate shaft 38 on. The Zwlsshenwelle

JiS- R. 3 f. Ι £

is guided in two roller bearings 39, 40 designed as deep groove ball bearings, the outer rings of which are both pressed into receiving bores in the bearing block. The intermediate shaft 38 is pressed into the generously dimensioned roller bearing 40 on the handle side and is mounted in the inner ring of the other roller bearing 39 with a sliding fit.

A swash plate body 4l consisting of two axially juxtaposed parts 4l ', 4l "is pressed onto the intermediate shaft 38. An annular groove 42 is arranged on the circumference of the swash plate body 4l, the axis of which is inclined to the axis of the swash plate body. In the annular groove 42 is rotatable and via axial needle bearings A ring 43, supported on the flank-n ^{v of} the annular groove, is guided on which a radially extending tappet 44 is arranged. The tappet 44 drives the hammer mechanism

45 of the hammer drill.

Between the roller bearing 39 and the swash plate body 4l are arranged in the axial direction elastically deformed means. The elastic means are of a smaller diameter on the inner ring of the roller bearing 39 and with its larger diameter on the swash plate body 4l resting plate spring

46 formed. The disc spring conveniently compensates for the differences in distance between the axial contact surfaces on the intermediate shaft 38 and on the bearings 39, 40 caused by manufacturing tolerances as well as thermal expansion or wear in the bearings. It also leads to a slight axial preload of the two roller bearings 39, 40, which is important for the service life of the bearing, and to a rigid transmission of the high forces generated in the striking mechanism to the powerfully dimensioned roller bearing 40 Difficulties can be transmitted via the weakly pretensioned Te L Lei ^{1 spring.}

'Π i I-

The hammer mechanism 45 of the hammer drill is inside a stationary one Guide tube 47 arranged. It consists of an im Guide tube 47 tightly and slidably guided racket 48 and a drive member designed as a piston 49, likewise guided in a tight and sliding manner in the guide tube 48. In the wall The guide tube 47 has a plurality of passages which can be opened or closed by the racket 48.

The rear end of the piston 49 facing away from the striker 48 is fork-like and carries a pivot pin 50. In the center of the pivot pin 50, a transverse bore is arranged into which the plunger 44 engages with little play. As a result, the plunger 44 can easily move in the axial direction move the cross hole.

In the front end area of the interior, facing away from the piston 49 of the guide tube 47 extends the inner end of a drilling spindle 51. The front end facing the motor 9 the intermediate shaft 38 is in turn designed as a pinion 52, which meshes with a face-toothed collar 53 which is arranged on a rotary sleeve 54. The rotating sleeve is rotatably seated the front part of the fixed guide tube 47; on her the front end of the rotary sleeve 54 has internal teeth 55, the non-rotatably into a corresponding external spline of the rear end of the drilling spindle protruding into the guide tube 47 51 intervenes. The rotary sleeve 54 is supported on the one hand radially inside the face-toothed collar on the guide tube 47 and on the other hand with the internal toothing 55 on the drilling spindle 51. The almost always existing axial offset between Drilling spindle L and bearing point on the bearing block or the lift bearing block attached standing guide tube 47 accommodates this arrangement in a special way. Since dLe-mentioned radially inward of the federal 53 lying bearing point of the rotary sleeve 5 '! Is slightly ball-shaped, a slight angular misalignment can be achieved without disadvantageous consequences are accepted.

Between the ^{hammer mechanism 1} J 5 and the tool holder 8 arranged at the free end on the drilling spindle, the drilling spindle 51 is arranged with a sliding fit in two roller bearings 56, 57 designed as deep groove ball bearings. Between the roller bearings 56 , 57, the drilling spindle 51 has a collar 58 which engages in a space which is delimited in the axial direction by two stop shoulders 59, 60 which are supported by damping means on the housing of the hammer drill. Each shoulder stop 59, 60 is connected to a cylindrical outer surface of the drill spindle 51 which annularly surrounds body 61, 62 of a cushioning material - Polyamide here - formed. The two ring-shaped, mirror- inverted bodies Gl, 62 are each supported at the rear on the _{side facing away from the stop shoulders 59 3} 60 via an O-ring 63, 6 * J and the roller bearings 56, 57 in the housing of the hammer drill. For better centering of the annular bodies 6l, 62 each time the collar of the collar 58 hits the stop shoulders 59 , 60, the stop shoulders 59j 60 have the shape of an inner cone converging in the direction of impact, the collar 58 that of an associated outer cone converging in the same direction.

The construction of the hammer drill in the drilling spindle area is characterized by a robust and simple rotary drive through extremely effective damping of the axial forces in both directions and - through - a total of very robust, cheap, compact, lightweight and workshop-friendly design ». /: _ '} - [- ■ _ [': __ ..; ".-". ".

On the end face facing the tool holder 8: üä & Wckzla. gers 56- is eik ^ den. iötrenraüm ^ = the hammer to work convincing was te sealing Mchtring i y .angeordnet ^": ν ■"/·■-"...:;..;'_;";.: - vi" .-. "" -: ■ '■;

The eetriefer room. J ¹ * ⁷ is ^ - as Q & enffehön mentioned - to? Lubrication: - lubrication uncf for ": cooling:" Samtifeh & r bearing share ^ owie'-des Schlag * - s ^ at least- partially filled with oil: ^ MerÖ ^ eii ^; ia.s & eri: /

ORiQiNALiNSPECTED

the best lubrication conditions can be achieved until the oil is completely used up, as well as good heat transfer conditions. A condition for this, however, is that the gear space is sealed so that the oil cannot escape. It has been shown, however, that if the gear space is not ventilated to the outside, high pressures and, when the hammer drill cools down, also negative pressures can arise afterwards. To prevent this, the gear housing is provided with an oil-tight vent. This consists of a ventilation duct 66, which extends through the wall 32 from the engine interior connected to the outside air. The ventilation channel 66 is arranged in a mandrel-shaped housing extension 67, the preferably sharp-edged end of which ends in the interior of a coaxial bore 68 in the intermediate shaft 38. At the inner end, the coaxial bore 68 has a radial opening 69 which opens in the base of the annular groove 42 of the swash plate body 4l. There is a narrow sealing gap 70 between the end face at the end of the intermediate shaft 38 on the pinion side and the housing wall 32 forming the foot area of the housing extension 67.The described ventilation channel 66 ensures effective ventilation of the gear space 34, which reliably prevents the above-described overpressures or underpressures . The pointed outflow of the housing extension 67 and the centrifugal effect on the oil penetrating into the bore 68 prevent oil from penetrating through the vent into the engine compartment, even if the oil suddenly accumulates there like a surge. Adequate lubrication of the needle bearings supporting the ring 53 is also guaranteed via the radial opening 69.

In a modification of the invention - without having to take into account the narrow sealing gap 70 - the front opening of the coaxial Bore 68 from the intermediate shaft 38 is closed by a sealing washer not shown in detail in the drawing are, on the one hand, the wall of the coaxial bore of the

- 10 -

809825/0042

Vd- R.

Intermediate shaft 38 and on the other hand the thorn-shaped housing extension 67 touched. The venting then no longer takes place via the narrow sealing gap 70 but directly via the radial opening 69 into the base of the annular groove 42 and the bore 68 to the venting channel 66.

A rotary movement of the swash plate body 4l, as can be easily seen, produces a reciprocating movement of the piston 49. When the tool clamped in the tool holder 8 is placed on a workpiece - i.e. on a masonry to be machined -, whereby the drilling spindle 51 in the position shown in Figure 1 arrives, in which the inner end of the same, which carries an external splined shaft toothing, protrudes into the striking mechanism 45, the striking mechanism is in its striking position, via the air cushion formed between the piston 49 and the hammer 48, which acts as an energy store, the striker 23 is also set in an axial reciprocating motion. When it hits the inner end of the drilling spindle 51, the hammer emits its energy, which ultimately acts as an axial impact on the tool held in the tool holder 8. From the position shown in FIG. 1, the drilling spindle performs a certain axial movement forwards, but this does not go so far that the collar 58 comes into contact with the front shoulder 59. Since the tool and mostly also the workpiece to be machined When it comes to highly elastic materials, the tool experiences a rebound towards the hand-held power tool after the so-called Α-impact just described, the so-called B-impact the shoulder 60 is incident. in this way, the annular body 62 made of plastic or nylon, the damping force on the O-ring 64 forwards it to the rear bearing 57 'which the blow discharge into the enclosure. By this arrangement, a minimum of noise during

• 09825/0042

Hammer drilling achieved by the described B-punches. In addition, of course, the strain on the wrists and arms is also increased of the operator working with the hand machine tool is reduced.

If the operator takes the hand tool from the workpiece from, the drilling spindle 51 can move forward until finally the collar 58 hits the front shoulder 59. If the hammer is removed from the workpiece while the hammer is in operation, the hammer 58 initially becomes at least one more Exercise axial run-out on the spindle 51. The spindle 51 will then impinge on the front shoulder 59, where the blow then occurs is damped in the same way as described above for a B-beat. The striking mechanism 45 is now in its idle position, in which the hammer 48, since the drilling spindle 51 is in its foremost possible position, can move to the front end of the guide tube 47. The striking mechanism is now so that the striker 48 does not return to the striking mechanism during the described transition to idle rebounds equipped with a bat arrester. This racket catching device consists of a Workpiece-side end of the guide tube 47 held, elastic expandable O-ring 71. The racket 48 now has a damping collar 73 at its front free end on the circumference, whose diameter is larger than the inner diameter of the undeformed O-ring 71 · The damping collar has at its - in Movement direction of the piston 48 seen - front and rear side conical transition surfaces to the cylindrical outer surface of the extension 72, the diameter of which corresponds essentially to the inner diameter of the undeformed O-ring 71. At the Transition of the hammer mechanism to idle, the bat with its damping collar 73 now thaws into the O-ring, whereby the-. water is deformed, as a result of which part of its kinetic energy is consumed, while the greater part of its kinetic energy

- 12 -

• 09825/0042

- . vi - R. 3p ι ε

energy is still delivered to the drilling spindle 51. The after the return of the hammer 48 from the drill spindle 51 The O-ring 71 absorbs the remaining small rebound energy completely and holds the racket 48 safely in the idle position. Should the striking mechanism now be in its striking position again are brought, the hammer only has to be placed back on the workpiece, whereby the drilling spindle 51 is pushed back and the racket 48 again from the O-ring 71 pushes out. Of course, the racket catcher is used not limited to the handheld power tool described here or the percussion mechanism described here. The racket catching device can also be used with striking mechanisms provided with a crank drive.

- 13 -

8098 25/00

. scr .

Claims (1)

R. '7. '■ ■ Expectations Q / hand tool with an electric motor driven percussion mechanism, in which a racket connected in particular via an air cushion to a drive element executing an axial reciprocating movement delivers its energy to a rotatably arranged tool guided in the hand machine tool, characterized in that between the percussion mechanism (45) and the work-receiving tool holder (8) a drilling spindle (51) which conducts the rotary movement and the axial impacts is guided axially movably and rotatably in two bearings (56, 57) and that the drilling spindle (51) between the bearings (56, 57) has a Has collar (58) which engages in a space which is limited in the axial direction by two stop shoulders (59, 60) which are supported by damping means on the housing (2, 3) of the handheld power tool (1). 2. Hand tool according to Claim 1, characterized in that the stop shoulder (59, 60) on one of the cylindrical ones Outer surface of the drilling spindle (51) at least partially ring-shaped surrounding body (61, 62) made of damping material, especially if special polyamide. 3 Hand machine tool according to Claim 1 or 2, characterized in that that the stop shoulder is supported at the rear on an O-ring (63, 64). 80982S / Q042 4. Hand tool according to one of the preceding claims, characterized in that the drilling spindle (51) is guided with a sliding fit in roller bearings (56, 57), preferably deep groove ball bearings, pressed into the housing (2, 3), the support of the stop shoulder (59, 60 ) happens via the roller bearings (56, 57) in the housing (2, 3). 5. Hand machine tool according to one of the preceding claims, characterized in that the stop shoulder (59, 60) the Shape of an inner cone converging in the direction of impact, the collar (58) that of an associated converging converging in the same direction Has outer cone. 6. Hand machine tool with an armature of the electric motor arranged in two bearings, in particular according to one of the preceding claims, characterized in that elastic means (14) are provided which hold the bearings (11, 12) against one another in the axial direction to press. 7 · Hand machine tool according to Claim 6, characterized in that the armature shaft (13) on the pinion side in an axial force on the inner ring of a first pressed into a metal bearing block (33) Rolling bearing (12) transmitting manner is performed that the other, a fan wheel (l6) carrying end of the drive shaft (I3) also in a manner transmitting axial force to the inner ring - 15 -. 809825/0042 is guided in a second roller bearing (11), which in a Rubber bushing (14) is held, which is so braced that the armature shaft (13) exerts a force in the direction of its pinion side The end experience is greater than any force that occurs in any operating state and is directed in the opposite direction to this force. 8. Hand machine tool according to Claim 7, characterized in that that the fan wheel-side bearing (11) with a press fit on the Armature shaft (13) held deep groove ball bearing and the pinion-side bearing (12) held with a sliding fit, pressed against one Stop ring (36) is adjacent deep groove ball bearing. 9 · Hand machine tool in which the striking mechanism is via a swash plate drive is moved, which has a guided in two bearings shaft with a swash plate body, in particular after a of the preceding claims, characterized in that the bearings designed as roller bearings, in particular deep groove ball bearings (39, 40) are pressed with their outer rings in a bearing block (33), preferably made of aluminum, that the Shaft (38) is guided with a sliding fit in the inner ring of the first (39) and with a press fit in the inner ring of the second bearing (40) and that between the first bearing (39) and the swash plate body (41) elastically deformed means (46) are arranged in the axial direction are. - 16 - 80982B / 0042 - 1 # - row 3 j 10. Hand machine tool according to claim 9, characterized in that the elastic means are formed by a plate spring (46) resting with its smaller diameter on the inner ring of the first roller bearing (39) and with its larger diameter on the swash plate body {kl). 11. Hand machine tool with an electric motor having a commutator, preferably a universal motor, in which the commutator-side Motor bearing in a housing cover similar to a bearing plate is arranged, which is fastened in particular by a fitting in the motor housing, in particular according to claim 1, thereby characterized in that between the motor housing (2) and the housing cover (3) a quiver-shaped brush guides (21) and thread (22, 23) e.g. B. for cable connections having brush holder plate (19) is adjusted, the side facing away from the electric motor designed as an air guide disc (20) for the fan (16) is and on the side carrying the brush guides (21) holding extensions (27) for the laminated stator (28) of the Electric motor (9) are arranged. 12. Hand machine tool according to Claim 11, characterized in that that the brush guides (21) in relation to the axis of the current v. wenders (17) run radially and that their rear, after ends that open outward are closed by cover plates (26) secured by means of screws (25). - 17 - 809825 / 00A2 - 17 - row 3 Γ ί? Hand machine tool with a sealed housing interior, at least partially filled with oil, with oil-lubricated hammer mechanism and / or gear arranged therein and oil-tight ventilation, in particular according to claim 1, characterized in that a ventilation duct (66) extends from a space connected to the outside air which ends in a mandrel-shaped housing extension (67) , the preferably sharp-edged end of which ends inside a coaxial bore (69) in a rotating shaft (38) in the gear space (34). I ¹ J. Hand machine tool according to Claim 13 , characterized in that there is a narrow sealing gap (70) between the end face in the shaft (38) and the housing wall (32) forming the foot area of the housing extension (67). 15 · Hand machine tool according to Claim 13 _3, characterized in that the coaxial bore (68) has a radial opening (69) at its inner end. 16. Hand machine tool according to Claim 15, characterized in that that the front opening of the coaxial bore (68) from the shaft (38) is closed by a sealing washer, on the one hand the shaft (38), on the other hand, touches the mandrel-shaped housing extension (67). - 18 - 80982S / 0042 (ο - * - ^R - 3 6 i 6 17. Hand tool according to claim l6, characterized in that the sealing washer is made of slightly elastic material , in particular polyurethane foam. 18. Hand machine tool according to claim 1, with an upright, the hammer mechanism receiving guide tube on which a coaxially the rotary movement of the tool passing rotary sleeve is guided, the drive end of which has a face-toothed collar and the output side of the drilling spindle engaging internal toothing, characterized in that the rotary sleeve (5 ¹ J) is supported on the one hand radially inside the face-toothed collar (53) and on the other hand with the internal toothing (55) on the drilling spindle (51). 19 Hand machine tool according to Claim 18, characterized in that that the bearing point of the rotary sleeve (54) lying within the collar (53) is designed as an annular bead with a spherical inner surface is. 20. Hand machine tool with a hammer mechanism in its guide tube an axially freely movable racket is guided, in particular according to claim 1, characterized in that on the front, workpiece-side At the end of the guide tube (47) an elastically expandable O-ring (71) is held, into which at the transition of the Svhlagwerks (45) in idle on one at the front - 19 - ■ 809825/0042 2655898 side of the racket (4 &) seated port set (72) Cushioning collar. (73), the diameter of which is larger than the inner diameter of the undeformed O-ring (71) is immersed. 21. Hand tool according to Claim 19, characterized in that the damping collar (73) has conical transition surfaces to the cylindrical outer surface of the extension (72) , the diameter of which is essentially the inner diameter of the undeformed O-ring (71). , "■ 809825/0042