EP1281483B1 - Rotary hammer - Google Patents

Description

The invention relates to a rotary hammer or chisel hammer with the features according to the preamble of claim 1. Such a hammer drill is, for example US-A-2 638 325 known.

Rotary hammers or chisels for drilling in stone or concrete and for performing chiselling have a tool spindle for receiving a drill, a chisel or similar tools. The longitudinally displaceable tool is acted upon by a percussion with blows in its longitudinal direction, whereby a chisel effect is achieved with the tool used. A usually switched on or switched off executed rotary drive is provided for the generation of a rotational movement of the tool spindle in combination with the percussion to perform drilling. The striking mechanism and the rotary drive are typically driven by a common drive motor.

Especially in a rotary hammer for professional use, for example, in a heavy version of the 10kg class, the percussion includes a crank mechanism with a crankshaft and a connecting rod. The connecting rod acts, for example via a spring and in particular by means of a piston on pneumatic way on the tool spindle.

In conventional embodiments, the crank mechanism is driven by a spur gear, which requires a complex bearing of the crank mechanism because of the high mechanical load of the hammer mechanism. A combination of radial and thrust bearings is provided for receiving the forces occurring and for fixing the individual parts in their predetermined position. Corresponding bearing seats and / or bearing blocks hold the individual bearings. The high number of items is costly. The assembly is expensive, the items are not fixed before the completion of the full installation and can fall out, for example, during maintenance.

The invention has for its object to provide a rotary hammer, which requires a reduced installation and maintenance in the field of its transmission.

The object is achieved by a hammer drill with the features of claim 1.

For this purpose, it is proposed to form the drive for the impact mechanism in the form of a gear pair, which consists of a bevel gear fixed to the crank and a bevel gear engaging in the bevel gear whose axes of rotation are at an angle, in particular at an approximately right angle to each other. In this case, the crank wheel is mounted so as to be longitudinally displaceable by means of a radial shaft bearing. The longitudinal displaceability of the crank wheel is limited in one direction by a thrust bearing and in the opposite direction by the bevel pinion. The flying storage leads to a simple mountability by attaching the crank wheel to the storage. In particular, in conjunction with the seated directly on the drive shaft of the drive bevel pinion, the final determination of the crank wheel by mounting the drive motor. Its bevel pinion acts as a thrust bearing and as a safeguard against axial slipping out of the crank wheel. On the additional cost of a further axial storage or anti-skid can be dispensed with.

Due to the angular arrangement of the axes of rotation of bevel pinion and crank wheel to each other constructively a wide range of desired ratios can be realized, with the angular arrangement of the Rotary axes a compact, slim design of the transmission is possible. In this case, the bevel gear and the Kurbelradnabe are designed as two separate components to reduce the manufacturing costs, wherein the bevel gear is fixed to the Kurbelradnabe and in particular festgelötet. The bevel pinion is appropriate directly on the drive shaft of the drive motor and engages directly into the bevel gear. In particular, the bevel pinion is integrally formed with the drive shaft for ease of manufacture. As a result, the number of gear parts is kept small. The above design contributes to the compact and lightweight design of the hammer drill.

The radial shaft bearing suitably comprises a needle bearing and is in particular designed as a pair of needle bearings. As a result, a high bearing capacity is given low volume, especially for absorbing the impact loads from the percussion. Under load needle bearings have a low elastic deformation, whereby repercussions on the mutual alignment of the gears in the drive are avoided. Due to the paired arrangement of two needle bearings in addition to a high radial stiffness and high rigidity in tilt direction is given.

In an advantageous development, the crank wheel is rotatably supported by means of the radial shaft bearing about a particular hollow executed, fixed housing stud bolts. As a result, the shaft bearing can be arranged on the inside of the crank wheel in the region of the drive, the output and the crank mechanism. The bearing has at least approximately no eccentricity compared to the forces acting, whereby the bearing forces and the deformations occurring are minimized. In a hollow design of the stud bolt a favorable ratio of weight to strength and rigidity is achieved. In an embodiment of the transmission housing made of light metal, in particular aluminum, a cast-in steel bushing for receiving the stud bolt is advantageously provided. The Leichtmetallguß of the gear housing leads to a high rigidity and insensitivity to shocks, wherein the cast-steel bushing initiates the concentrated bearing force in the stud bolt flat while avoiding voltage spikes in the light metal housing. The pouring of the steel bushing leads in addition to a simple production and reliable power and heat transfer. The stud bolt can be fixed with little effort, for example by pressing in the steel bushing.

In an expedient development of the diameter of the housing-fixed stud in the region of the radial shaft bearing is smaller than the outer diameter of the cast-in socket. As a result, on the one hand, in particular in a plastic gear housing, the forces occurring are low. On the other hand, the cast-in socket forms a shoulder, which can serve as Axialgleitlager or to support a separate thrust bearing. In an advantageous variant of the stud is pressed directly into the gear housing, wherein the diameter of the stud in the region of the radial shaft bearing is smaller than in the gear housing area. The thicker area of the stud for pressing into the gear housing takes in one-piece training, the function of the steel bushing was. In addition, a reduction of the items is given and a simplification of the assembly allows.

In an expedient development of the power flow in the hammer drill is performed by the drive motor via the crank mechanism of the striking mechanism in the rotary drive. For this purpose, an output is provided in the region of the crank hub, via which the Kurbelradnabe acts on the tool spindle for generating the rotational movement. The Kurbelradnabe is characterized a multifunction part in which branches the power flow in the direction of the impact mechanism and the rotary drive. This multifunctional part can be manufactured and assembled as a unit. The crank mechanism of the impact mechanism and the rotary drive of the tool spindle can be mounted independently of the drive motor and brought into operative connection with each other. During maintenance work, the drive motor dismantled as a unit. In the case of the crank drive, which is still in engagement with the rotary drive, a functional check can be carried out manually.

The output is based on the crank pin of the crank mechanism in the direction of its axis of rotation on the same side of the Kurbelradnabe arranged as the drive. This allows a simply configured, based on the connecting rod unilateral bearing the Kurbelradnabe, the Kurbelradnabe can be mounted together with the storage without consideration of a connecting rod or a link control. On the additional design effort on both sides of the connecting rod arranged storage with an additional bearing block is omitted.

The drive motor acts directly on the Kurbelradnabe only, the required tolerances in the corresponding drive with little effort can be maintained. The tolerance insensitivity leads not only to cost-effective manufacturability but also to a corresponding longevity.

The output in the region of the crank hub is expediently formed by a further pair of gears with two gears designed in particular as spur gears. In a design of the gear pair as a pair of spur gears results in a simple, inexpensive production, the gear pair has a high load capacity and low tolerance insensitivity. The lying on the crank gear of the second gear pair is expediently formed integrally with the Kurbelradnabe, which in addition to reduced manufacturing costs, a high power transmission from the Kurbelradnabe on the gear even with small dimensions is possible.

In an expedient development, an intermediate shaft is provided between the output and the tool spindle, on which the second gear of the gear pair is provided by the output. By the arrangement an intermediate shaft, a strong speed reduction of the tool spindle can be structurally predetermined, whereby relative to the spindle speed, a high impact frequency of the striking mechanism is adjustable. This allows a high drilling performance with low tool wear. The arrangement of an intermediate shaft in conjunction with a strong reduction allows the choice of tooth pairings in a geometrically favorable range. The intermediate shaft expediently comprises a torque-limiting safety clutch, via which the corresponding gearwheel is connected. The safety coupling in the intermediate shaft area requires no additional space. Inadvertent seizure of the drilling tool, only the rotary drive is interrupted. About the ongoing impact mechanism, the drilling tool can be worked out. The power transmission from the intermediate shaft to the tool spindle is advantageously carried out via a bevel pinion on the intermediate shaft, which engages in a bevel gear on the tool spindle. By axial displacement of the bevel gear on the tool spindle, the rotary drive can be interrupted in a simple manner to use the hammer drill, for example, for chiselling. The drive motor and the tool spindle are expediently arranged axially parallel to one another, resulting in an overall slim design of the hammer drill. Working even in confined spaces is relieved. The center of gravity of the hammer drill is close to the axis of the tool spindle, whereby the hammer drill can be performed in impact operation with improved accuracy.

Fig. 1

einen Längsschnitt durch einen 10kg-Bohrhammer als Übersichtsdarstellung;

Fig. 2

eine Ausschnittsvergrößerung der Darstellung nach Fig. 1 im Bereich der fliegend gelagerten Kurbelradnabe;

Fig. 3

einen Längsschnitt durch ein weiteres Ausführungsbeispiel eines Bohrhammers;

Fig. 4

eine Ausschnittsvergrößerung der Anordnung nach Fig. 3 im Bereich der Kurbelradlagerung.

An embodiment of the invention is described below with reference to the drawing. Show it:

Fig. 1

a longitudinal section through a 10kg hammer drill as an overview;

Fig. 2

an enlarged detail of the representation after Fig. 1 in the area of the overhung crank wheel hub;

Fig. 3

a longitudinal section through a further embodiment of a hammer drill;

Fig. 4

an enlarged detail of the arrangement Fig. 3 in the area of the crank wheel bearing.

Fig. 1 shows a longitudinal sectional view of an overview of a 10kg hammer drill 1. The hammer drill 1 has at the rear a drive motor 4, which is designed in the illustrated embodiment as an electric motor. It may also be provided a combustion, hydraulic or pneumatic motor. At its end opposite the drive motor 4, a rotatable tool spindle 2 is mounted in a gear housing 5 in which an indicated tool 3, for example a drill, chisel or the like, is held. It is provided on the tool 3 acting percussion 6. In the gear housing 5 is a crank mechanism 7 is mounted as part of the hammer mechanism 6, which is driven by the drive motor 4. The crank mechanism 7 comprises a crank wheel 8, which is rotatable about a rotation axis 17. Eccentric to the axis of rotation 17, the crank 8 has a crank pin 11 which is in engagement with a connecting rod 9. About the connecting rod 9, a piston 32 is connected to the crank mechanism 7 and longitudinally displaceable oscillating drivable. The piston 32 is guided in the hollow tool spindle 2 and generates by means of its oscillating movement an oscillating air pressure in the tool spindle 2. The oscillating air pressure is pneumatically transmitted to a striker 33, which in turn strikes a striker 34 and thus over the striker 34 impact energy on the tool 3 applies.

Fig. 2 shows an enlarged view of the hammer drill 1 after Fig. 1 in the region of the crank mechanism 7 and the drive motor 4. In the impact mechanism 6, a transmission element 45 is provided between the crank wheel 8 and the piston 32. The transmission element 45 is shown in FIG Embodiment, the connecting rod 9, but can also be designed, for example, as a linearly longitudinally displaceable link or the like. The connecting rod 9 has a connecting rod 46, through which the crank pin 11 is guided. The crank pin may be integrally formed with the crank hub 10 or another component of the crank wheel 8. In the illustrated embodiment, it is a separate item and engages with press-fit in an end-side retaining opening 47 of the crank hub 10th

In the drive motor 4 designed as an electric motor, a drive shaft 19 with an armature 35 is rotatably mounted in a rear ball bearing 36 and a front ball bearing 37 about a rotation axis 18. The axis of rotation 18 of the drive shaft 19 is substantially perpendicular to the axis of rotation 17 of the crank wheel 8. Depending on the application, an arrangement in a different angle and, for example, an axially parallel arrangement may be appropriate.

The crank wheel 8 has a Kurbelradnabe 10, wherein between the Kurbelradnabe 10 and the drive motor 4, a drive 12 is provided, via which the drive motor 4 acts on the crank mechanism 7. The drive 12 may be an intermediate gear, a worm gear, a belt drive or the like. Be and is formed in the embodiment shown by a gear pair 14. From the angular arrangement of the two axes of rotation 17, 18 to each other results in a conical configuration of the gear pair 14. In an axis-parallel arrangement are advantageously provided spur gears. In the illustrated embodiment, the gear pair 14 consists of a bevel gear 10 fixed to the bevel gear 15 and a bevel gear 15 engaging bevel gear 16. The bevel gear 15 can be pressed with the bevel gear 10, screwed or the like. Be and is in the illustrated embodiment on the Kurbelradnabe 10th soldered. The bevel pinion 16 may be mounted on an intermediate shaft or the like and is fixed in the illustrated embodiment to the drive shaft 19 of the drive motor, as a result, the drive motor 4 with his Drive shaft 19 engages over the bevel pinion 16 directly into the bevel gear 15. The front ball bearing 37 of the drive shaft 19 is arranged in the immediate vicinity of the bevel pinion 16.

The crank wheel 8 is mounted by means of a radial shaft bearing 20 in the direction of its axis of rotation 17 longitudinally displaceable flying. On the conrod 9 side facing away from the radial shaft bearing 20, a thrust bearing 21 is provided. The longitudinal displacement of the crank wheel 8 is limited in one direction by this thrust bearing 21 and in the opposite direction by the bevel pinion 16. In particular, in a rotary hammer with low power 20 may be provided for the radial shaft bearing sliding or ball bearings. In the shown 10kg class high performance rotary hammer 1, the radial shaft bearing 20 is formed as a pair of needle bearings 22. For this purpose, a housing-fixed hollow running stud 23 is provided, around which the crank wheel 8 is rotatably supported by means of the needle bearing 22. Depending on the application, it may also be appropriate to provide the crank wheel 8 with a pivot pin which engages in a bearing bush or the like. In the gear housing 5. The stud bolt 23 can be screwed into the gear housing 5, pressed or cast directly. In the illustrated embodiment, it is pressed into a steel bushing 24. The steel bushing 24 in turn is cast in the gear housing 5 made of cast aluminum. It may also be expedient to press the steel bush 24 into the transmission housing 5. As materials for the transmission housing 5, other light metals such as magnesium or injection-molded plastic are suitable.

In the area of the crank wheel hub 10, an output 13 is provided, via which the crank wheel hub 10 acts on the tool spindle 2 to produce a rotational movement. The output 13, based on the connecting rod 9 in the direction of the axis of rotation 17, on the same side of the Kurbelradnabe 10 as the drive 12. The output 13 may be a worm drive or the like. And is in the illustrated embodiment a another gear pair 25. The output 13 can act directly on the tool spindle 2. In the embodiment shown, an intermediate shaft 28 is provided, which is rotatably mounted about a substantially parallel to the axis of rotation 17 of the crank wheel 8 shaft shaft 42. The gear pair 25 is formed in this embodiment of two gears designed as spur gears 26, 27. In an angular arrangement of the shaft axis 42 to the rotation axis 17, the gears 26, 27 are preferably formed as bevel gears.

The crank wheel side gear 26 of the gear pair 25 is integrally formed with the Kurbelradnabe 10. The gear 27 on the side of the intermediate shaft 28 is designed as a separate component and fixed by a torque limiting safety clutch 29 on the intermediate shaft 28. Integral with the intermediate shaft 28, a bevel pinion 30 is formed, which engages in a bevel gear 31 on the tool spindle 2. The tool spindle 2 has on the outside a toothing 38 on which the bevel gear 31 is rotatably mounted. By a longitudinal displacement of a coupling sleeve 54 in the direction of the double arrow 39 is a torque transmitting connection between the bevel gear 31 and the tool spindle 2 on or disengaged. As a result, the rotary drive is required for drilling on and off, for example, for chiselling. The intermediate shaft 28 has on its side facing away from the bevel pinion 30 a stub axle 44 which engages in a blind hole 43 in the gear housing 5 and is mounted there by means of needle bearings 40. It can also be a storage about a stud bolts comparable to the storage of the crank wheel 8 appropriate.

In the illustrated embodiment, the spindle axis 41 of the tool spindle 2 and the axis of rotation 18 of the drive shaft 19 are arranged substantially parallel to each other. Perpendicular to this are the axis of rotation 17 of the crank wheel 8 and the shaft axis 42 of the intermediate shaft 28. Depending on the application, any other angular arrangements may be appropriate.

The simple, fast and cost-effective installation of the arrangement shown is carried out by first the assembly of the intermediate shaft 28 with the bevel pinion 32 and the spur gear 27 is inserted into the needle bearing 40. Subsequently, the crank wheel 8 is pushed onto the stud bolt 23, the piston 32 is suspended with the connecting rod 9 on the crank pin 11, the bevel gear 31 is positioned and the tool spindle 2 is pushed by the bevel gear 31 and the piston 32. Finally, the drive motor 4 is fixed to the transmission housing 5, wherein the bevel pinion 16 forms the longitudinal stop for the crank wheel 8. As a result, the said parts are now fixed in their operating position. For maintenance or the like. Dismantling can be done in the reverse order in a comparable simple manner.

Fig. 3 shows a longitudinal sectional view of another embodiment of a hammer drill 1 with a rotatably mounted tool spindle 2, through which a tool 3 is rotatably driven. Coaxial with the tool spindle 2, an electric motor 4 is provided which drives a striking mechanism 6 and the bevel pinion 30 and the bevel gear 31, the tool spindle 2 rotationally. In the illustrated embodiment, the bevel gear 16 is formed integrally with the drive shaft 19 on the drive shaft 19 of the drive motor 4. The stud bolt 23 is pressed into a ribbed, cast-in in the gear housing 5 steel bushing 24. The steel bushing 24 may also be pressed into the transmission housing 5. The steel bush 24 has a larger diameter than the stud bolt 23 in the region of the radial shaft bearing 20 for the Kurbelradnabe 10. A thrust bearing 21 for the Kurbelradnabe 10 is designed as a sliding bearing and supported on the steel bushing 24 frontally. The stud bolt 23 has a coaxial downwardly open bore 48 in the form of a blind hole. The transmission housing 5 is suitably a Leichtmetallguß- or plastic injection molding.

Fig. 4 shows in an enlarged detail the arrangement Fig. 3 In the region of the crank hub 10. In this case, a variant of the stud 23 is provided, which has a radially enlarged paragraph 49 in the region of the gear housing 5, whose diameter is greater than the diameter of the stud 23 in the region of the radial shaft bearing 20. The stud and the paragraph 49 are integrally formed, wherein the stud bolt 23 is pressed with the paragraph 49 in the transmission housing 5 directly.

Claims (14)

1. Hammer drill (1) or chipping hammer with a tool spindle (2) for the location of a tool (3), with a drive motor (4) and with a hammer (6) acting on the tool (3) and located in a gear housing (5), which comprises a crank drive (7) with a crank gear (8) rotatable about an axis of rotation (17), wherein the crank gear (8) comprises a crank boss (10) and a crank pin (11) and wherein between the crank pin (11) and the drive motor (4) there is provided a drive (12), by way of which the drive motor (4) acts on the crank drive (7), characterised in that the drive (12) comprises a bevel gear (15) located on the crank boss (10) and a bevel pinion (16) meshing with the bevel gear (15), their axes of rotation (17, 18) extending at an angle relative to one another, and in that the crank gear (8) is over-mounted for longitudinal movement by means of a radial shaft bearing (21), wherein the longitudinal movement is limited by a thrust bearing (21) in one direction and by the bevel pinion (16) in the other direction.
2. Hammer drill according to claim 1,
   characterised in that the radial shaft bearing (20) comprises at least one needle roller bearing (22) and is in particular designed as a pair of needle roller bearings (22).
3. Hammer drill according to claim 1 or 2,
   characterised in that the crank gear (8) is mounted rotatably about an in particular hollow stud (23) located on the housing by means of the radial shaft bearing (20).
4. Hammer drill according to claim 3,
   characterised in that the gear housing (5) is made of a light metal, in particular of aluminium or magnesium, or of plastic, into which a steel bushing (24) is cast to accommodate the stud (23).
5. Hammer drill according to any of claims 1 to 4,
   characterised in that the diameter of the stud (22) located on the housing is smaller in the region of the radial shaft bearing (20) than the outer diameter of the cast- or pressed-in bushing (24).
6. Hammer drill according to claim 3,
   characterised in that the stud (23) is pressed directly into the gear housing (5), the diameter of the stud (23) being smaller in the region of the radial shaft bearing (20) than in the region of the gear housing.
7. Hammer drill according to any of claims 1 to 6,
   characterised in that the bevel pinion (16) is mounted on a drive shaft (19) of the drive motor (4) and directly meshes with the bevel gear (15), the bevel pinion (16) being in particular designed as a single part together with the drive shaft (10).
8. Hammer drill according to any of claims 1 to 7,
   characterised in that the bevel gear (15) is non-rotatably joined and in particular soldered to the crank boss (10).
9. Hammer drill according to any of claims 1 to 8,
   characterised in that an output (13) is provided in the region of the crank boss (10), by way of which the crank boss (10) acts on the tool spindle (2) to generate the rotary motion, wherein, relative to the crank pin (11), the output (13) is located on the same side of the crank boss (10) as the drive (12) in the direction of the axis of rotation (17).
10. Hammer drill according to claim 9,
    characterised in that the output (13) is designed as a second pair of gears (25) with two gears (26, 27) designed in particular as spur gears.
11. Hammer drill according to claim 10,
    characterised in that the gear (26) is designed integral with the crank boss (10).
12. Hammer drill according to any of claims 1 to 11,
    characterised in that between the output (13) and the tool spindle (2) there is provided an intermediate shaft (28) with the gear (27), which in particular includes a torque-limiting safety clutch (29).
13. Hammer drill according to claim 12,
    characterised in that the intermediate shaft (28) supports a bevel pinion (30), which meshes with a bevel gear (31) on the tool spindle (2).
14. Hammer drill according to any of claims 1 to 13,
    characterised in that the drive motor (4) and the tool spindle (3) are arranged to be axially parallel to one another.

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