EP0016771B1 - Hand mechanical tool - Google Patents

Abstract

A power-driven hand mechanical tool, operating in particular as a drilling or percussive machine, wherein a rotating mandrel (20) with an air percussive part (13) are movable. The percussive part (13) comprises a concentric driving sheathing (28) which has a guiding surface (30) with maximum (32) and minimum (33) axial curve, said curve being closed and presenting an inclination which increases and decreases constantly. A claw (31) clamp onto a neighbouring location of the guiding surface (30) at the immediate vicinity of the driving piston (21) of the percussive device (13). A fastener (35) prevents the claw (31) from moving freely without guiding along the guiding surface (30) while, in the axial direction, the claw is held with some degree of freedom for sweeping a guiding surface (30).

Description

The invention relates to a hammer drill or impact hammer designed as a hand power tool, with an electric drive motor, by means of which a rotary sleeve with a tool holder acted upon by it, in which a tool can be guided, can be driven in rotation, and by means of which an air cushion is also driven. Percussion mechanism is drivable, which contains a club which delivers its impact energy to the tool, and which has a translational drive which works on the air cushion percussion mechanism and which has a drive member which can be driven all round and which has a circumferentially closed self-contained slope and an essentially continuously increasing and decreasing gradient Guide surface with at least one curve maximum and curve minimum directed in the axial direction and at least one driver designed as a rolling and sliding body which scans the guide surface and acts on the drive piston for its axial displacement.

Such a hand tool is known from DE-A 1 -2449191. The drive motor drives a swashplate as part of the striking mechanism via a motor pinion and the gearwheel that engages with it, which sits in a rotationally fixed manner on an intermediate shaft, which in turn carries another gearwheel which meshes with a gearwheel which is seated on the rotating sleeve. The rotary sleeve in turn also has a toothing which engages in a toothing of the die holder of the tool holder for its rotary drive. Four gearwheels are therefore necessary on the transmission side, and furthermore the two further toothings on the rotating sleeve and on the associated striker. These many gears are expensive, take up a lot of space in the machine and make them expensive, relatively large and heavy and therefore bulky. Another disadvantage of the transmission is that the cost of bearings for all the described transmission parts is considerable, which also has a disadvantageous effect on the price, dimensions and weight of the machine. The translation drive and its striking mechanism also have many disadvantages. The drive member is represented by the swash plate, which, as a curve guide, contains an annular groove which runs transversely but obliquely to the drive axis of the swash plate. In this annular groove a ring is rotatably held relative to the swash plate, which has a protruding driver pin which engages a piston pin of the drive piston. The drive piston is non-rotatably guided. This design of the striking mechanism with translation drive is very complex and leads to relatively high production costs. It also takes up a lot of space inside the machine. It also has the disadvantage that the force which acts on the drive piston for its axial back and forth movement acts eccentrically on the drive piston, so that the longitudinal guidance of the piston is thereby additionally stressed and subjected to additional wear. A rotation of the swashplate as the drive member results in an axial impact on the tool. In order to achieve a high number of strokes, the swash plate must be driven at a relatively high speed. On the other hand, since the swash plate is heavily stressed, it must be designed so that it can withstand the stresses even for a long time. This leads to a strong and heavy design of the swash plate with a driver guided on it. This results in relatively large rotating masses in this area. Otherwise, this design is expensive and also requires a high weight of the machine.

An electrically powered hand hammer has become known from DE-B-10 07 148, which, however, is only used for generating strikes. This hammer has a spring hammer mechanism, which is driven by the electric motor from a rotating to a translatory movement via a converter having a ball and curve guide. The spring hammer mechanism, however, has the considerable disadvantage that, because of its large masses, it either builds very large and tends to generate very strong vibrations which stress the operator working with the hand hammer or, if the masses are kept small, has only a comparatively very low impact capacity .

The invention has for its object to provide a hand tool described above, which is compared to known simpler, cheaper, compact, lighter and smaller and at the same time less vibration with a significantly simplified drive for the reciprocating movement of the drive piston and the tool. In particular, the number of necessary gears of the transmission and the total necessary bearings should be reduced. At the same time, the oscillating masses and thus the vibration load on the operator handling the machine are to be reduced. In everything, the advantages provided by the air spring hammer mechanism and the possibility of driving the tool not only axially but also simultaneously or independently of it should be retained.

The object is achieved in a hand machine tool of the type mentioned according to the invention in that the drive member from one to the drive piston and Racket coaxial and both concentrically surrounding drive sleeve is that the guide surface of the drive sleeve is provided with curve maxima and curve minima directed in the axial direction, that the driver engages directly on the drive piston on the guide surface adjacent location and that the rolling or sliding body by means of a bearing in the circumferential direction , preferably approximately cage-like, forced holder against free, uncontrolled migration along the guide surface secured in the axial direction, however, is held with a degree of freedom for scanning this guide surface.

This training creates the conditions for making the entire transmission and striking mechanism as simple as possible, specifically as a result of the drive sleeve, which concentrically surrounds the drive piston and racket. A special translational drive for the drive piston, which is to be arranged at a radial and axial distance from the arrangement of the drive piston and racket, is omitted, so that the otherwise otherwise e.g. space below the longitudinal central axis of the drive piston is no longer required. The machine can thus be made much more compact and smaller. In addition, it can be trained much easier and cheaper and also lighter in weight. On the transmission side, it is only necessary to provide the drive sleeve with a gearwheel which engages with a drive pinion of the drive motor.

So only two gears are required. This and the concentric arrangement of the drive sleeve make it possible to minimize the number of bearings and necessary bearings. This also has a favorable effect on reducing the size, weight and price of the machine, without foregoing the advantages of the air spring impact mechanism and the possible rotary and impacting action on the tool holder for the tool. It is also advantageous that the circulating masses are reduced and furthermore the oscillating masses can be kept as small as possible, so that a low vibration load for the operator handling the machine can thereby be achieved. The forced holder for the rolling or sliding body ensures that the latter always remain at a predetermined distance in the circumferential direction from each other when the drive sleeve rotates, so that there are very specific, predetermined drive conditions and impact rates for the tool which do not change during operation. The striking mechanism is switched on when the forced holder is held in a rotationally fixed manner and the drive sleeve is rotating. The hammer mechanism can be switched off by simple means by releasing the rotationally fixed fixing of the forced holder. Then the forced holder rotates together with the drive sleeve, but without the drive piston being driven axially back and forth. The striking mechanism stands still. Depending on the structural conditions, the drive conditions can be interchanged, i.e. the drive sleeve is held in a rotationally fixed manner and instead the forced holder is driven all round. The invention also opens up the possibility of driving both the drive sleeve and the forced holder in a rotating manner, but preferably in opposite directions to one another, whereby the advantage is achieved that the ratio of the number of impacts to the speed of the tool can be selected such that e.g. When used as a rotary hammer, the drilling progress and smooth running of the machine result in an optimal drilling pattern.

An advantageous embodiment provides that the number of alternating curve maxima and curve minima of the guide surface is selected such that in particular three axial strokes can be applied to the racket and thus to the tool per full rotation of the rotating drive sleeve or forced holder. Three strokes per revolution have proven to be the cheapest solution, as this results in three through-grooves with a segment angle of 60 ° when impact drilling. This is completely sufficient to achieve good drilling progress and a relatively quiet run.

Is chosen for the guide surface has a deviating from the sine wave, asymmetric, for example, leveling, so this results in the advantage that the reciprocating movement of the drive piston, shops _r windiness and acceleration can adapt to the necessary conditions better, for example, so that the Return stroke with suction movement is slower and the forward stroke with compression and subsequent acceleration phase of the club against the tool is faster.

A further advantageous embodiment provides that two or preferably three or more rolling or sliding bodies arranged at equal angular distances from one another in the circumferential direction are provided. Two such bodies are sufficient. They ensure that the forces driving the drive piston axially act centrally on the drive piston, which enables very low loads on the guide of the piston and other guide surfaces and high stability even over a long service life.

It can be advantageous if the rolling or sliding bodies are designed as rollers, balls, sliding blocks or the like and preferably are hollow on the inside. This keeps the masses floating around as small as possible.

The forced bracket can be rotatably or rotatably driven in the housing relative to the drive sleeve and / or via a clutch optionally be released for rotation from the non-rotatable position. In the case of a non-rotatable arrangement, the percussion drive takes place via the circumferential drive sleeve. If the forced holder is released for rotation, the striking mechanism is switched off, as already explained at the beginning. If the forced holder is in turn driven in rotation, the drive sleeve can instead be held in a rotationally fixed manner. This represents the reversal of the first-mentioned drive conditions. Instead, however, it is also possible to also drive the drive sleeve at the same time, and advantageously in the opposite direction to the forced holder. This has the advantage that the ratio of the number of impacts to the number of revolutions of the tool is not or must be an integral multiple, but can also be a fractional number. With this design, extremely high impact rates can be achieved with a relatively low number of drives.

A further advantageous embodiment provides that the drive sleeve and / or the rotary sleeve and / or the tool holder are integral with one another or at least have a rotationally fixed drive connection with one another and that all of them are arranged coaxially with one another. The racket works directly on the tool, so that an intermediate drilling spindle e.g. is unnecessary with a die. The arrangement described is structurally simple and cheap and reduces weight. Dimensions and costs.

Instead of the above-described training, the arrangement can also be such that the latter and / or the rotating sleeve and / or the tool holder are integral with one another or are at least in a rotationally fixed drive connection in the case of a rotationally driven forced holder.

It can also be advantageous if the drive sleeve has a coaxial inner or outer circumferential toothing or a coaxial gear, in particular spur or bevel gear, on the end facing away from the racket, which is coupled directly to the drive sleeve in a rotationally fixed manner or via a safety coupling, and when the Drive motor carries a drive pinion on the motor shaft, which is in engagement with the peripheral toothing or the gear. So only two gear wheels of the transmission are necessary with a corresponding reduction in the number of bearings and bearings.

In a further advantageous embodiment, the guide surface is arranged on an axial end surface of the drive sleeve and is designed as an axial cam surface. The latter is arranged on a radially projecting ring shoulder on a peripheral part of the drive sleeve facing away from the racket. Both the racket and the drive piston are sealed and slidable and arranged one behind the other within the drive sleeve and the rotating sleeve, which is in particular one-piece, and is non-rotatable. With this design, the drive piston and racket are both seated inside the drive sleeve and axially one behind the other. It is advantageous if the forced bracket is formed from at least one radial bearing pin, which at the end carries a sliding body or a roller rotatable about the pin axis, which runs on the axial cam surface, and when the bearing pin is held in a rotationally fixed manner relative to the housing and preferably by means of an axial compression spring with its sliding body or the roller can be pressed against the axial cam surface. It can also be advantageous if the bearing pin is designed as a piston pin that diametrically penetrates the drive piston and is held in it, with sliding bodies or rollers arranged at each end. The bearing pin and the drive piston can be supported on the housing in a non-rotatable manner by means of the axial compression spring and preferably can be released for rotation. Furthermore, the arrangement in this design can be such that the drive sleeve with one-piece rotating sleeve and one-piece tool holder in the axial region of the tool holder on the one hand and the annular shoulder with axial cam surface on the other hand is each mounted in the housing by means of a bearing, in particular a roller and / or roller bearing. So only two bearings are necessary, which store the one-piece part, consisting of drive sleeve, rotating sleeve and tool holder, in the housing. The interior of the drive sleeve with rotating sleeve is optimally used by the racket and drive piston inside. The two sliding bodies or rollers are held at a distance of 180 ° in the circumferential direction by the piston pin. Since the piston pin is fixedly connected to the drive piston in the circumferential direction, both form a unit. By means of suitable means, pins, protrusions or the like. Or also by means of the axial compression spring, the drive piston is held in the housing in a rotationally fixed manner with piston pins and sliding bodies or rollers held thereon. At the same time, the sliding bodies or rollers are pressed against the axial cam surface via the axial compression spring. So you follow this cam surface. Rotation of the drive sleeve with the cam surface leads to the cam surface moving past the spatially fixed sliding bodies or rollers and the axial movement of the drive piston thereby being reciprocated. This action does not apply if the non-rotatable mounting of the drive piston with piston pin and sliding bodies or rollers is removed. Then the drive piston rotates together with the drive sleeve without a relative movement between the axial cam surface on the one hand and sliding bodies or rollers on the other hand. The striking mechanism is then switched off. Nevertheless, the tool is still driven in rotation. The axial compression spring has the advantage that it is so can be designed so that it responds at maximum compression of the air spring of the air spring hammer mechanism and thus intercepts the maximum pressure and makes the machine softer and more comfortable to use. It goes without saying that in the power flow, for example between the tool holder and the drive sleeve, a safety coupling of a conventional type can be arranged to protect the operator when the tool is stuck, in particular a drill.

The drive sleeve can be driven via an internal toothing or an external toothing at its end facing away from the tool holder, which meshes directly with a drive pinion on the motor shaft of the drive motor. So only two gear teeth are necessary. The internal spacing keeps the center distance as small as possible. Better coverage is also achieved.

Instead, the guide surface can also be arranged on the inner circumferential surface of the drive sleeve. It can be designed as a guide trough with an approximately circular arc-shaped trough cross section. At least one, preferably two or three, balls which engage in the guide trough can be provided as the driver. With this design, the guide surface in the form of the guide groove is thus placed in the inner peripheral surface of the drive sleeve. It therefore has here on the inner circumferential surface of the drive sleeve an approximately band-shaped sine curve in the circumferential direction or an asymmetrical curve deviating therefrom.

It can also be advantageous if the drive piston is designed as a hollow piston, in particular as such with one end of the axial piston sleeve open towards the tool holder, within which the racket is guided tightly and slidably. This leads to extremely short dimensions in the axial direction of the drive piston.

A further advantageous embodiment provides that the piston sleeve has on the outer circumferential surface a driving surface, in particular an annular groove, on which or in which the at least one ball engages as a driver. In this configuration, the forced holder can be formed from a guide sleeve, which contains an at least substantially axially extending guide slot for each ball, within which the ball is held approximately in a cage-like manner, but is movable in the direction of extension of the guide slot. It can also be advantageous if the guide slot provided for each ball is inclined at an acute angle to an imaginary, axial cylinder surface line or is curved. This also results in an asymmetrical curve deviating from the sinusoidal shape with the advantage that the back and forth movement of the drive piston, speed and acceleration can be better adapted to the necessary conditions, in a similar manner as by a course of the guide surface deviating from the sinusoidal shape.

It is advantageous if the guide sleeve runs coaxially with the hollow piston with the piston sleeve and concentrically surrounds the latter and leads inside. Another advantageous embodiment provides that the drive sleeve surrounds the guide sleeve at a radial distance and at least to the axial length over which the at least one guide slot extends, and that each ball positively guided in a guide slot in the radial direction through the guide slot and on the one hand into the Guide groove and on the other hand engages in the annular groove.

With this principle of the guide trough with balls placed in the inner circumferential surface of the drive sleeve, one rotation of the drive sleeve while the guide sleeve is held in place means that the balls have to follow the course of the guide trough and are thus displaced back and forth in the axial direction. The movement of the balls takes place within the guide slots of the guide sleeve. Since the latter is fixed, the balls are thus supported against circumferential movement and thereby forced to follow the course of the guide trough. Since the balls permanently engage in the annular groove of the piston sleeve, the balls transmit the axially back and forth movement to the piston sleeve, as a result of which the drive piston is driven oscillatingly back and forth. With this design, too, only two bearings are required for mounting the drive sleeve and the rest of the device, just as the transmission has only two gearwheels, namely one on the drive sleeve and also a drive pinion on the motor shaft. The arrangement of the gears is thus as simple as possible.

It goes without saying that this arrangement can be reversed kinematically, that is to say, for example, the guide sleeve cannot be arranged in a rotationally fixed manner, but instead can be driven in rotation. If the drive sleeve is then held in a rotationally fixed manner, the drive piston is driven back and forth in the same way. In this case, the guide sleeve would then be connected in a rotationally fixed manner to the rotary sleeve and tool holder, so that the rotary rotary drive on the tool is then generated via the rotating guide sleeve. This design also opens up the possibility of optionally holding the drive sleeve in a rotationally fixed manner or releasing it for rotation. In the latter case, the drive sleeve would then rotate together with the rotating guide sleeve and no forced movement of the balls along the guide trough would be generated. The reciprocating drive movement for the drive piston would be switched off, and thus the striking mechanism. However, the tool would still be driven in rotation via the circumferential guide sleeve. At the same time, this design opens up the possibility of driving not only the guide sleeve, but also the drive sleeve all around, but preferably in opposite directions to one another. This enables extremely high impact rates, which can be determined via the gear ratio in the transmission.

The rotating sleeve is advantageously coupled to the tool holder in a rotationally fixed manner and is mounted in the coupling area in the housing.

The rotating sleeve can be in one piece with the drive sleeve and the drive sleeve can be rotatably mounted on the end facing away from the tool holder, preferably on the guide sleeve, and its gear can be in gear engagement with a drive pinion of the motor shaft.

The guide sleeve can be held in the housing in a rotationally fixed manner.

Instead, the arrangement can also be such that the rotary sleeve is connected in a rotationally fixed manner to the guide sleeve and the guide sleeve is rotatably mounted in the housing and carries a drive gearwheel which engages with a drive pinion of the motor shaft. Then the drive takes place through the guide sleeve with the rotary sleeve held in a rotationally fixed manner.

It can also be advantageous if the drive sleeve is held in the housing in a rotationally fixed manner via a switchable, non-positive or positive-locking coupling, but can be released for rotation. This opens up the possibility of switching off the striking mechanism by switching the clutch and enabling the drive sleeve to rotate.

A further advantageous embodiment provides that the drive sleeve, which is arranged in a rotationally fixed manner but rotatable when the clutch is released, is coupled to a gear wheel which, together with the drive gear of the driven guide sleeve, is in engagement with the drive pinion of the motor shaft, but preferably in the opposite direction to the drive gear the driven guide sleeve is driven. So here both the drive sleeve and the guide sleeve are driven, the latter simultaneously guiding the rotary drive to the tool via the rotationally fixed rotary sleeve and tool holder. This arrangement has the advantage that the ratio of the number of impacts to the number of revolutions of the tool is no longer or has to be an integral multiple, but can be a fractional number. Depending on the selected number of teeth on the gear wheel of the drive sleeve, the drive gear wheel of the guide sleeve and the drive pinion, an optimal drilling pattern for the drilling progress and smooth running of the machine designed as a hammer drill can be selected and defined. When the clutch is released, the drive sleeve can be uncoupled from the positive rotary drive, so that it is then not driven in a rotating manner via the gear wheel, but can rotate together with the driven guide sleeve. The hammer mechanism is then switched off, but the tool is still driven in rotation.

Another advantageous embodiment provides that the piston sleeve has a radially recessed ball pocket on its outer circumferential surface as a driving surface for each ball, within which each ball is coupled non-displaceably to the drive piston in the axial direction and in the circumferential direction, and that the drive piston in turn by means of a switchable Coupling is held in a rotationally fixed manner relative to the housing or, when the coupling is released, together with the drive sleeve can be rotated relative to the housing. The clutch is so switchable that the hammer mechanism is switched on or switched off in the other case. The rotary drive movement generated for the tool via the rotating drive sleeve is still retained.

In an advantageous further development, the coupling can have a central ball cage with coupling balls held therein, axially parallel or also approximately helical ball troughs for engaging one coupling ball each on the drive piston and an outer switching ring, which has receiving pockets on its inner surface for each coupling ball, in which, when the coupling is released, the radial Coupling balls emerging from the ball grooves can be received, so that the striking mechanism is then switched off in this position of the coupling. The outer switching ring, which can be rotated to switch the clutch, can be actuated by conventional gear means with access from the outside of the machine.

It can also be advantageous if the central ball cage of the clutch is held in the housing in a rotationally fixed manner and supports the drive piston. In this configuration too, only two bearings, which are arranged at a distance from one another in the axial direction, are necessary for mounting the entire system, and furthermore only the drive pinion and a gearwheel on the drive sleeve.

In all of the described embodiments, the motor shaft with the drive pinion can be aligned either axially parallel or at an angle to the longitudinal axis of the drive piston. The arrangement parallel to the axis is made possible by the design described and allows the drive motor to be accommodated approximately in the axial extension of the drive piston and close to the handle area of the machine. This allows the machine to be kept extremely small in diameter near the handle. In the case of an angular course of the motor shaft, the drive motor can sit in an adapted housing part, which at the same time has a grip character and can be handled from the outside as an additional handle.

It can also be advantageous if the tool holder on the end facing the racket has a catch device for the racket in its ejected idle position. The catching device can have a clamping ring, in particular an O-ring, within the tool holder and on the racket an annular shoulder with shoulders that drop radially on both sides in the axial direction, or vice versa.

• Fig. 1 einen schematischen, teilweisen axialen Längsschnitt eines Bohrhammers gemäß einem ersten Ausführungsbeispiel,
• Fig. 1 a eine Antriebshülse als Schlagwerkantrieb für den Bohrhammer gemäß Fig. 1,
• Fig. 2 eine schematische Ansicht der abgewickelten inneren Umfangsfläche der Antriebshülse mit darin enthaltener Führungsrinne des Bohrhammers gemäß Fig. 1,
• Fig. 3 einen schematischen axialen Längsschnitt eines Teiles eines Bohrhammers unterhalb der Längsmittelachse gemäß einem zweiten Ausführungsbeispiel und oberhalb der Längsmittelachse gemäß einem dritten Ausführungsbeispiel,
• Fig. 4 und 5 jeweils einen schematischen axialen Längsschnitt eines Teiles eines Bohrhammers gemäß einem vierten bzw. fünften Ausführungsbeispiel,
• Fig. 6 eine schematische Seitenansicht mit teilweisem Längsschnitt eines Bohrhammers gemäß einem sechsten Ausführungsbeispiel,
• Fig. 7a, 7b und 7c einen Halbschnitt entlang der Linie A-A in Fig. 6 bzw. einen Viertelschnitt entlang der Linie B-B bzw. C-C in Fig. 6 einmal bei eingeschaltetem Schlagwerk bzw. im anderen Fall bei ausgeschaltetem Schlagwerk,
• Fig. 8 eine schematische Seitenansicht mit teilweisem axialem Längsschnitt einer Schlagbohr-Vorsatzeinrichtung,
• Fig. 9 eine schematische Seitenansicht mit teilweisem axialem Längsschnitt eines siebten Ausführungsbeispieles eines Bohrhammers.

The invention is explained in more detail below with reference to exemplary embodiments shown in the drawings. Show it:

• 1 is a schematic, partial axial longitudinal section of a hammer drill according to a first embodiment,
• 1a a drive sleeve as a hammer mechanism drive for the hammer drill according to FIG. 1,
• 2 is a schematic view of the developed inner peripheral surface of the drive sleeve with the guide groove of the hammer drill according to FIG. 1 contained therein,
• 3 shows a schematic axial longitudinal section of a part of a rotary hammer below the longitudinal central axis according to a second exemplary embodiment and above the longitudinal central axis according to a third exemplary embodiment,
• 4 and 5 each show a schematic axial longitudinal section of a part of a hammer drill according to a fourth or fifth embodiment,
• 6 is a schematic side view with a partial longitudinal section of a rotary hammer according to a sixth embodiment,
• 7a, 7b and 7c a half section along the line AA in FIG. 6 or a quarter section along the line BB or CC in FIG. 6 once with the striking mechanism switched on or in the other case with the striking mechanism switched off,
• 8 is a schematic side view with a partial axial longitudinal section of an impact drilling attachment,
• Fig. 9 is a schematic side view with partial axial longitudinal section of a seventh embodiment of a rotary hammer.

The hammer drill shown in Fig. 1 has a housing 10 in which an electric drive motor 11, which is designed as a universal motor, a gear 12 and a striking mechanism 13 are arranged. At the rear end, the housing 10 merges into a handle 14, into which a switch 15, which is provided with a pusher 15, is installed, via which the drive motor 11 can be started. At the lower end of the handle 14, a power supply cable 17 is inserted through an elastic grommet 16. At the front end facing away from the handle 14, a tool holder 18 is arranged in the housing .10, which is used to hold an indicated tool 19, e.g.

Drill or chisel. The tool holder 18 can be rotatably driven via the gear 12 via a rotary sleeve 20 in the interior of the housing 10. The striking mechanism 13 is also driven by the gear 12. It has an axially reciprocating drive piston 21 which acts on a striker 23 via an air cushion 22. The latter delivers its impact energy directly to the tool 19. A component of the striking mechanism 13 is also a translational drive 24 working on the drive piston 21, which will be explained in more detail below and has a drive element which can be driven in rotation with a cam guide and two drivers which scan the cam guide and act on the drive piston 21 for its axial displacement.

- Part of the transmission 12 is a conical drive pinion 25, which is non-rotatably on the motor shaft 26. The drive pinion 25 meshes with a ring gear 27 of the transmission 12. The motor shaft 26 is oriented at an obtuse angle to the longitudinal axis of the drive piston 21.

The drive member of the translation drive 24 consists of a drive sleeve 28 which is integral with the rotary sleeve 20. The latter is non-rotatably connected to the tool holder 18, e.g. shrunk tight on the latter. The tool holder 18, the rotating sleeve 20 and the drive sleeve 28 thus adjoin one another in the axial direction and are aligned coaxially with one another. The drive sleeve 28 is arranged coaxially with the drive piston 21 and the striker 23 and surrounds both concentrically.

The drive piston 21 is designed as a hollow piston and has an axial piston sleeve 29 pointing towards the tool holder 18 and open there, within which the striker 23 is tightly and slidably guided.

On its inner circumferential surface, the drive sleeve 28 (FIG. 1a) carries a guide surface designed as a guide groove 30 with an arc-shaped groove cross section. Within the guide trough 30 two balls run, of which only one ball 31 is visible in FIG. 1. The guide trough 30 is self-contained in the circumferential direction and in this case has an incline that increases and decreases essentially continuously in the circumferential direction, with curve maxima 32 and curve minima 33 directed in the axial direction. As FIG. 2 shows, the guide trough 30 has an approximately band-shaped configuration in the circumferential direction the drive sleeve 28 placed on sinusoid. However, the course can also be designed to deviate from a sinusoidal line, that is to say asymmetrically, as a result of which the back and forth movement of the drive piston 21, the speed and acceleration can be adapted even better to the necessary circumstances, for example in such a way that the return stroke with suction movement takes place more slowly and the forward stroke with compression and subsequent acceleration phase of the striker 23 against the work stuff 19 is done faster. The number of alternating curve maxima 32 and curve minima 33 of the guide trough 30 is selected such that three axial impacts can be applied to the striker 23 and thus to the tool 19 per full revolution of the rotating drive sleeve 28.

As can be seen, the ball 31 engages directly on the drive piston 21 on the guide groove 30 at a radially adjacent location. For this purpose, the drive piston 21 has, on its piston sleeve 29, specifically on its outer peripheral surface, a driving surface designed as an annular groove 34, in which the ball 31 engages.

The balls, of which only the ball 31 can be seen, are secured against free, uncontrolled migration along the guide trough 30 by means of a forced holder which is preferably approximately cage-like in the circumferential direction, but are held in the axial direction with a degree of freedom for scanning the guide trough 30. This restraint consists here of a guide sleeve 35 which contains an at least substantially axially extending guide slot 36 and 37 for each of the two balls. In the guide slot 36 is. the visible ball 31 is held approximately like a cage, in the other guide slot 37 the other, e.g. Sphere offset and not visible by 180 ° in the circumferential direction.

The holder in the guide slots 36 and 37 is such that each ball 31 is movable in the direction of extension of the guide slot 36. The guide slots 36, 37 run exactly axially here. Instead, they can also be inclined to an imaginary, axial cylinder surface line, e.g. be set at an acute angle, which also allows a better adaptation of the back and forth movement of the drive piston 21, the speed and acceleration to the necessary conditions.

As can be seen, the guide sleeve 35 runs coaxially with the drive piston 21 with the piston sleeve 29, the guide sleeve 35 concentrically surrounding the drive piston 21 and simultaneously leading radially and axially in the interior. The drive sleeve 28 surrounds the guide sleeve 35 at a radial distance and at least on the axial length over which the sinusoidal guide groove 30 extends. Each ball 31 or ball that is not visible in the associated guide slot 36 or 37 engages in the radial direction through the assigned guide slot 36, 37 on the one hand in the guide groove 30 and on the other hand in the annular groove 34 of the piston sleeve 29.

In the exemplary embodiment shown in FIG. 1, the guide sleeve 35 is held in the housing 10 in a rotationally fixed manner. It also serves to mount the drive sleeve 28, which is mounted in the area of the ring gear 27 by means of a ball bearing 38 on the fixed guide sleeve 35. At the left end in FIG. 1, the bearing in the area of the rotating sleeve 20 relative to the housing 10 likewise takes place by means of a ball bearing 39.

The tool holder 18 has at the end facing the racket 23 a safety device in the form of an O-ring 40 for the racket 23 in its ejected, idle position, not shown. A component of this catching device is furthermore on the racket 23 a radially projecting ring shoulder 41 with shoulders 42 and 43 which drop radially in the axial direction on both sides.

The tool 19 has two axial grooves on the inserted shaft, into which an invisible wedge of the tool holder 18 engages for rotational driving. Furthermore, at least two holding balls 44, 45 are held within the tool holder 18, which engage in axial recesses 46 and 47 of the tool 19, respectively, in such a way that the tool 19 is secured in the axial direction within the tool holder 18 against falling out and at the same time axially in it. and can be moved around.

When the drive motor 11 is switched on, it drives the ring gear 27, which is connected to the drive sleeve 28 in a rotationally fixed manner, via the motor shaft 26 with drive pinion 25. Via this rotary drive of the drive sleeve 28 and thus one-piece rotary sleeve 20, the tool holder 18 connected therewith in a rotationally fixed manner and thus the tool 19 is driven in rotation. During this rotation of the drive sleeve 28, the roughly sinusoidal guide groove 30 incorporated therein also rotates. As a result, the balls 31, which are prevented from rotating within the guide slots 36 of the fixed guide sleeve 35, inevitably move within the sinusoidal guide groove 30 and thus become alternately shifted left and right in the axial direction. Since the balls 31 engage radially inward in the annular groove 34 of the piston sleeve 29, this results in a reciprocating displacement actuation of the drive piston 21 and — via the air cushion 22 — a percussion drive during the axial displacement in FIG. 1 to the left on the racket 23, which in turn strikes against the facing end of the tool 19, so that axial shocks act on it. If, during handling with the tool 19, the rotary hammer is pressed against a wall, for example, the rotary drive movement of the tool 19 is exerted on this axial stroke in a superimposed manner. Whenever the striker 23 with its ring shoulder 41 has passed over the O-ring 40 in the axial direction, which is deformed somewhat in the radial direction, the O-ring 40 endeavors to engage in the rear shoulder 43 and the striker 23 in this ejected idle position to keep. Due to the axial pressure acting on the racket 23 via the tool 19, the racket 23 is freed from this catch position and axially ver to the right in FIG. 1 pushed so that the bat 23 on the air cushion 22 repeatedly experiences impacts and acceleration acting in the axial direction to the left.

It is not shown that in the first embodiment e.g. in the flow of force between the ring gear 27 and the drive sleeve 28 or the rotating sleeve 20 or the tool holder 18, a safety clutch can be arranged to protect the operator.

The second exemplary embodiment shown in FIG. 3 below the longitudinal central axis differs from the first exemplary embodiment only in that here the motor shaft 126 with drive pinion 125 is aligned axially parallel to the drive piston 121 and that, in addition to a ring gear on the drive sleeve 128, a spur gear 127 is seated in a rotationally fixed manner is engaged with the drive pinion 125.

The third exemplary embodiment shown in FIG. 3 above the central axis differs from the second exemplary embodiment in that the spur gear 227 does not act directly on the drive sleeve 228, but in between a safety coupling 248 which triggers in the axial direction and is known per se, which responds when it responds , decouples the drive sleeve 228 from the rotary drive via the spur gear 227, which then continues to spin freely. If the safety clutch 248 responds in this way, not only the striking mechanism, but also the rotary drive for the tool is switched off.

If, in a modification of the third embodiment, the safety clutch is in the power flow between the drive sleeve 228 and e.g. the rotating sleeve 220 or the tool holder 218 is switched on, then it can be achieved that only the rotary drive for the tool is switched off when the safety clutch responds, whereas the striking mechanism continues to work and applies axial shocks to the tool.

The fourth exemplary embodiment shown in FIG. 4 differs from the previous exemplary embodiments in that the rotary sleeve 320 is now connected in a rotationally fixed manner to the guide sleeve 335 instead of the drive sleeve 328, which in turn is rotatably mounted in the housing 310 by means of the ball bearing 338. The spur gear 327, which meshes with the drive pinion 325 of the motor shaft 326, is thus connected in a rotationally fixed manner to the guide sleeve 335 in this exemplary embodiment. The drive sleeve 328 is a non-positive or positive, e.g. manually switchable clutch held in rotation in housing 310, but can be released for rotation by actuating this clutch. The clutch is e.g. from between an outer switching ring 349 and the outer circumferential surface of the drive sleeve 328 arranged, approximately needle-like rolling elements 350 and also an invisible inner clamping surface on the outer switching ring 349. By rotation, the switching ring 349 is adjustable so that the rolling elements 350 a radial clamping force on the Exercise the drive sleeve 328 so that the drive sleeve 328 is then held in a rotationally fixed manner. As a result of the rotary drive of the guide sleeve 335, the balls 331 within the guide slots 336, 337 are forced to pass through the guide groove 330 in the fixed drive sleeve 328, so that the drive piston 321 is driven back and forth in the axial direction in the same way as in the first exemplary embodiment. In this fourth exemplary embodiment according to FIG. 4, the drive conditions are only reversed compared to the first exemplary embodiment according to FIG. 1. With the drive sleeve 328 held in place, the tool is driven both by rotation and by impact drive.

If the switching ring 349 is rotated in such a way that its inner clamping surface moves radially away from the rolling elements 350, then that which acts radially on the drive sleeve 328 becomes. Clamping force released and the latter free to rotate together with the driven guide sleeve 335 and the balls 331. There is then no reciprocating drive of the drive piston 321. However, the tool is still driven in rotation via the guide sleeve 335, the one-piece rotating sleeve 320 and the tool holder 318. So only the striking mechanism stands still.

In another embodiment, not shown, the coupling of the drive sleeve 328 described is designed instead of a non-positive, e.g. such that a locking pin engages radially in a recess of the drive sleeve 328 to stop it. The locking pin can be pulled out radially to release the drive sleeve 328. The scope of the invention also includes other non-positive and also positive couplings which act in the same way.

The exemplary embodiment shown in FIG. 5 roughly combines the elements of the third exemplary embodiment in FIG. 3 with those of the fourth exemplary embodiment in FIG. 4. Also in the fifth exemplary embodiment in FIG. 5, the rotating sleeve 420 is connected to the guide sleeve 435 in a rotationally fixed manner. The latter is driven by the drive pinion 425 on the motor shaft 426 via the spur gear 427, which is rotatable therewith. The drive sleeve 428 is rotatably supported by means of two ball bearings 451, 452 on the rotary sleeve 420 or the guide sleeve 435. In the embodiment shown below the longitudinal central axis, an internally toothed drive wheel 453 is seated on the drive sleeve 428, the teeth of which are also in engagement with the drive pinion 425 of the motor shaft 426. Here, the drive sleeve 428 is also driven by the drive pinion 425, but in the opposite direction to the direction of rotation of the guide sleeve 435. This The embodiment does not provide a shutdown via clutch. It has the advantage that the ratio between the number of blows and the number of revolutions of the tool is or must not be an integral multiple, but can also be a fractional number. This exemplary embodiment makes it possible, depending on the selected number of teeth of the drive pinion 425, the spur gear 427 and the internally toothed drive wheel 453, to select and define an optimum drilling pattern for drilling progress and smooth running of the rotary hammer, for example. This can be achieved by producing a much larger number of impacts on the tool with one rotation of the guide sleeve 435. In this exemplary embodiment, the tool is driven in rotation via the guide sleeve 435 and thus one-piece rotary sleeve 420. If instead the rotary sleeve 420 is connected in a rotationally fixed manner to the drive sleeve 428, the rotary drive of the tool takes place via the drive sleeve 428.

A modification is shown above the longitudinal central axis in FIG. 5, which enables the striking mechanism to be switched off, the tool still being driven in rotation via the guide sleeve 435 and rotary sleeve 420. In this configuration, the internally toothed drive wheel 453 is not connected to the drive sleeve 428 in a rotationally fixed manner. Rather, a coupling part 454 is provided, which engages with at least one inner radial tooth 455 in a form-fitting manner in an associated axial groove 456 of the drive sleeve 428 and is displaceable therein in the axial direction. The drive wheel 453 is rotatable relative to the drive sleeve 428. It e.g. 5 to the left in FIG. 5, in which, under the action of a spring 458, an associated driver on the coupling part 454 engages axially in FIG. 5 to the right. This engagement position is shown in Fig. 5 above the longitudinal central axis. In this case, the drive sleeve 428 is driven, specifically via the drive wheel 453, the axial toothing 457, the coupling part 454 and the radial tooth 455 engaging in the axial groove 456. In this state, the same results as in that shown in FIG. 5 below the longitudinal central axis Embodiment.

To switch off the beat, e.g. 5, so that the coupling part 454 is disengaged from the axial teeth 457 of the drive wheel 453 in the axial direction. The latter is still driven by the drive pinion 425, but the rotary drive for the drive sleeve 428 is then switched off. When the guide sleeve 435 is driven, it rotates with it, so that no axially reciprocating drive movement acts on the drive piston 421. However, the rotary drive for the tool still takes place via the guide sleeve 435 and rotary sleeve 420.

The exemplary embodiment shown in FIG. 8 uses the principle explained above for an impact drilling attachment 560 that is in the chuck 561 e.g. a conventional hand drill with a pin 562 is clamped. The guide sleeve 535 is connected in a rotationally fixed manner to the pin 562 and is integral with the rotary sleeve 520, which is connected in a rotationally fixed manner to the tool holder 518. The drive sleeve 528 is rotatably mounted on the guide sleeve 535 by means of two ball bearings 551, 552, but is held immovably in the axial direction. In this respect, the conditions correspond to the exemplary embodiment shown in FIG. 5 below the longitudinal central axis. For the rotary drive of the tool alone, the drive sleeve 528 is not attacked, so that it can rotate in the direction of rotation together with the guide sleeve 535. Then the striking mechanism is switched off. If the latter is to be switched on, the drive sleeve 528 is attacked by hand and this is prevented from rotating.

It is common to all of the aforementioned exemplary embodiments according to FIGS. 1-8 that the drive sleeve has on its inner circumferential surface the guide trough which is shown schematically in development in FIG. 2. Furthermore, in all the exemplary embodiments, the hollow piston is provided with a recessed annular groove on the outer circumferential surface of its piston sleeve, and a guide sleeve with essentially axially extending guide slots is also provided. In all exemplary embodiments, the drivers consist of balls which are hollow on the inside. For a central force application on the drive piston, at least two balls are provided, which are arranged at equal angular distances from one another in the circumferential direction. It can also be three or more balls. The guide sleeve has a guide slot for each ball. All balls engage on the one hand in the guide trough and on the other hand in the annular groove of the piston sleeve. In the schematic representation of the guide trough in FIG. 2, three axial impacts are generated on the tool per revolution of the tool 19. The following consideration leads to this design. If the guide trough is designed in such a way that only one stroke is generated per revolution of the tool 19, there is only one through-notch during drilling. If the design is such that two impacts are generated per revolution of the tool 19, there is also only one through notch during drilling, which is repeated after rotation through 180 °. With three impacts on the tool 19 per revolution, however, there are three through-notches with a segment angle of 60 °. With four impacts per revolution of the tool 19, there are only two through-notches with a segment angle of 90 °. This shows that the design of the guide trough with three Curve maxima 32 and three curve minima 33 the cheapest is also taking into account that this makes the hammer drill simple and extraordinarily light. There are three impacts per revolution of the tool 19. This is completely sufficient for drills, for example in the diameter range between 5 and 12 mm, in order to achieve good drilling progress and essentially smooth running.

In the sixth exemplary embodiment shown in FIGS. 6 and 7a-7c, the guide sleeve of the previous exemplary embodiments is missing. Furthermore, the piston sleeve 629 does not have an annular groove on its outer circumferential surface as a driving surface for each ball 663, 664, but instead a radially recessed ball pocket 665 or 666 for each ball. In this exemplary embodiment, a total of three balls are provided, of which only the two Balls 663, 664 can be seen. Accordingly, there are also three associated ball pockets on the piston sleeve 629. Each ball 663, 664 is coupled within the associated ball pocket 665 or 666 so as to be non-displaceable in the axial direction and in the circumferential direction with the drive piston 621. The restraint for the balls explained at the outset is thus formed here by these ball pockets 665, 666. To support against rotation, as a further element of the forced mounting, the drive piston 621 is held in a rotationally fixed manner relative to the housing 610 by means of a switchable coupling 667 or, when the coupling 667 is released, together with the drive sleeve 628 can be rotated relative to the housing 610. In the latter case, with clutch 667 released, the rotary drive movement for tool 619 is maintained while the striking mechanism is switched off.

As in the previous exemplary embodiments, the drive sleeve 628 has the guide groove 630 on its inner circumferential surface. The drive sleeve 628 is also in one piece with the rotary sleeve 620, which in turn is non-rotatably connected to the tool holder 618. The drive sleeve 628 carries a drive wheel 627 in a rotationally fixed manner. As in the previous exemplary embodiments, this can be in direct engagement with the drive pinion 625 of the motor shaft 626 or, as shown here only by way of example, mesh with an intermediate wheel 668 on an intermediate shaft 669, which in FIG an axial distance carries a gear 670 which engages with the drive pinion 625. The drive sleeve 628 is mounted in the area of the rotary sleeve 620 via the ball bearing 639 relative to the housing 610. The inner ring of the ball bearing is non-displaceably clamped axially between the rotary sleeve 620 and the tool holder 618. The outer ring of the ball bearing 639 is on the one hand direct and on the other hand via an interposed buffer ring 671, e.g. O-ring, supported against the housing 610. Through the latter, the impacts generated in the device and to be absorbed by the operator are dampened during handling, as a result of which the device can be handled more safely and quietly and without fatigue. In the area of the clutch 667, the drive sleeve 628 is mounted by means of a simple needle bearing 672, which is supported on part of the clutch 667.

Details of the coupling can be seen in particular from FIGS. 7b and 7c, of which the former shows the engaged position in which the striking mechanism is switched on, and the latter shows the disengaged position with the striking mechanism deactivated. The coupling 667 has a central ball cage 673 with coupling balls 674 held therein, further on the drive piston 621 axially extending ball grooves 675 for engaging one coupling ball each and, moreover, an outer, rotatably actuated switching ring 676. The latter carries on its inner surface receiving pockets 677 for each coupling ball, in which, when the clutch is released (FIG. 6 below the longitudinal central axis and FIG. 7c), the clutch balls 674 which have radially emerged from the ball grooves 675 can be received. The middle ball cage 673 of the clutch 667 is held in the housing 610 in a rotationally fixed manner and supports the drive sleeve 628 via the needle bearing 672 and also the drive piston 621 inside.

If the clutch is in the released position according to FIG. 7c, the drive piston 621 is not held in a rotationally fixed manner, but can rotate in the circumferential direction together with the drive sleeve 628 and the balls 663, 664, so that the striking mechanism is switched off, as before but the tool 619 is driven in rotation for drilling. By rotating the switching ring 676 from the rotational position according to FIG. 7c to that according to FIG. 7b, the coupling balls 674 disengage from the receiving pockets 677 of the switching ring 676. The coupling balls 674 are pressed radially inwards and into the ball grooves 675 of the drive piston 621. You couple the drive piston 621 with the non-rotatably held ball cage 673, so that in this position the drive piston 621 is held in a rotationally fixed manner and when the drive sleeve 628 rotates, the drive piston 621 is driven oscillatingly back and forth. The striking mechanism is thus switched on.

The seventh exemplary embodiment shown in FIG. 9 differs, for example, from the first exemplary embodiment according to FIG. 1 in that in the seventh exemplary embodiment the drive sleeve 728 is not only in one piece with the rotating sleeve 720, but also in one piece with the tool holder 718. This entire arrangement is mounted in the area of the tool holder 718 by means of the ball bearing 739 and at an axial distance therefrom by means of a roller bearing 778 in the housing 710. Inside the drive sleeve 728 are behind in the axial direction both the racket 723 and the drive piston 721 are tightly and slidably held and guided. The drive piston 721 is designed as a hollow piston, but without a piston sleeve.

The guide surface, which is self-contained in the circumferential direction and has an essentially continuously increasing and decreasing gradient, with curve maxima 732 and curve minima 733 oriented in the axial direction is arranged here on an axial end surface 779 on the side of the drive sleeve 728 facing away from the tool 719 and as an axial cam surface 780 designed, which is only shown in dashed lines in Fig. 9 for clarity. This axial cam surface 780 is located on a radially projecting annular shoulder 781 of a peripheral part of the drive sleeve 728 facing away from the striker 723. Two rollers 782, 783 are provided here as drivers, the roller axis of which extends radially and which are arranged at equal angular distances from one another in the circumferential direction. The rollers 782, 783 scan the axial cam surface 780 and rest on it. The forced holder for the rollers 782, 783 consists of a radial bearing pin in the form of a piston pin 784, which passes diametrically through the drive piston 721 and is held therein. The piston pin 784 carries the rollers 782 and 783, which are rotatable thereon, on both ends projecting radially beyond the drive piston 721. The piston pin 784 with the rollers 782, 783 is thus connected to the drive piston 721 in a non-rotatable manner in the circumferential direction. On the axial side facing away from the striker 723, an axial compression spring 785 presses against the drive piston 721, by means of which the rollers 782, 783 are pressed against the axial cam surface 780. The compression spring 785 is supported with its other end either non-influencably on the housing 7.10, as is not shown, or it is seated on a rotatable support pin 786 with a collar 787, on which the compression spring 785 is in turn non-rotatably held, but which in turn is optional is either rotatable in the housing 710 or can be fixed non-rotatably relative thereto. For this purpose, the support pin 786 can e.g. have a fork 788 on the side facing away from the compression spring 785, in which a locking pin 789 which can be actuated by hand engages in a radial locking manner. This engagement position is shown in Fig. 9. Then the compression spring 785 and, via this, the drive piston 721, which is non-rotatable thereon, are held in the housing 710 in a non-rotatable manner. A rotary drive of the drive sleeve 728 on the one hand effects the rotary drive of the tool 719 and on the other hand leads to the fact that the axial cam surface 780 rotates relative to the rollers 782, 783 held in the circumferential direction and the held piston 721. The rollers 782, 783 run on the cam surface 780, as a result of which the drive piston 721 is reciprocated in the axial direction.

If the locking pin 789 is pulled out of the fork 788 in the radial direction, the rotationally fixed support of the compression spring 785 relative to the housing 710 is omitted. The compression spring 785 can rotate and thus also the drive piston 721. When the drive sleeve 728 is rotated, this causes that together with the latter at the same time, the drive piston 721 rotates and is not driven back and forth. The striking mechanism is switched off, while the tool 719 is still driven in rotation.

The gear has here on the part 790 of the drive sleeve 728 which is elongated like a sleeve towards the right in FIG. 9, an internal toothing 791 which is in engagement with the drive pinion 725 on the axially parallel motor shaft 726. The internal toothing 791 has the advantage that a better overlap and at the same time a very small center distance between the drive pinion 725 and the toothing 791 are achieved in the transmission. Instead of the internal toothing 791, an external toothing or a separate gearwheel, which is connected in a rotationally fixed manner to the drive sleeve 728, can also mesh with the drive pinion 725.

In all of the exemplary embodiments, it is of essential advantage that the hammer drill is simple, cheap, compact, light, and at the same time small and low-vibration in design. The translational drive, which converts the rotary drive movement of the drive motor into a translational movement of the drive piston, is extremely simple and requires very few, essentially low-wear parts. The drive makes it possible, when designing the rotary hammer, to choose from the outset how many impacts are generated per revolution of the tool. Another advantage of the transmission is that you can get by with just two gears, namely the drive pinion on the motor shaft and the meshing teeth of the drive sleeve or guide sleeve. This significantly reduces the cost, size and weight of the hammer drill. In addition, there are no additional axes or shafts. The number of bearings is reduced to a minimum. This also reduces costs, weight and size. There are also very small oscillating masses and thus low vibration loads for the operator of the hammer drill. The fact that the racket works directly on the tool also makes the hammer much easier and simpler. The impact energy generated is used even better. It is also advantageous that with at least two drivers, the circumferential direction at equal angular intervals are arranged from each other and act on the drive piston, the drive piston is not acted upon by eccentric forces, but rather by centric forces. The embodiments shown in Fig. 1-8 with hollow piston and piston sleeve also allow to build extremely short in the axial direction. This reduces the size and weight of the hammer drill. The drivers, namely balls or rollers, can also be designed as differently designed rolling elements or sliding elements, for example rollers, sliding blocks or the like. In order to keep the oscillating masses as small as possible, these drivers can be made hollow.

1-8 all forces occurring during the back and forth movement in the guide raceways are positively received and supported, in the seventh embodiment according to FIG. 9 this is done by the compression spring 785. The latter has the advantage that it is so can be designed so that it responds at maximum compression of the air cushion 722 between the drive piston 721 and the striker 723 and thus intercepts the maximum pressure and thus makes the hammer drill softer and more comfortable to use.

Claims (37)

1. A drill hammer or percussive hammer in the form of a hand tool machine comprising an electric driving motor (11) by means of which a rotary sleeve (20) can be rotatably driven together with a tool receiver (18) influenced by the sleeve and in which a tool (19) can be guided, and furthermore by means of which an air cushion percussive mechanism (13) can be driven which comprises a striker (23) which delivers its impact energy to the tool (19) and has, acting on the air cushion percussive mechanism (13), a translational drive (24) which has a rotationally driveable driving element (28; 728) provided with a guiding surface (30; 780) continuous in a peripheral direction and moreover having a substantially constant increasing and decreasing inclination and provided with at least one axially directed curve maxima (32; 732) and curve minima (33; 733) and at least one follower (31) tracing the guiding surface (30; 780) and engaging the driving piston (21) in the form of a rolling and sliding member (31, 782, 783) for its axial displacement, characterised in that, the driving member consists of a driving sleeve (28; 728) coaxial with respect to the driving piston (21; 721) and the striker (23; 723) and concentrically surrounding both of them, that the guiding surface (30; 780) on the driving sleeve (28; 728) is provided with axially directed curve maxima (32; 732) and curve minima (33; 733), that the follower along the guiding surface (30 or 780) directly engages adjacent positions on the driving piston (21 or 721) and that the rolling or sliding member (31; 782, 783) secures against free uncontrolled deviation along the guiding surface (30 or 630 or 780) by means of an enforced mounting (35-37; 665, 667; 784, 785) supporting the rolling or sliding member in a peripheral direction, preferably in a substantially cage-like manner, but is axially retained with a degree of freedom for tracing the said guiding surface.

2. A machine according to claim 1, characterised in that, the guiding surface (30; 780) has a sinusoidal path in a peripheral direction arranged substantially in the form of a strip on the driving sleeve (28; 728).

3. A machine according to claim 1, characterised in that, for better adaptation to the to and fro movement, speed and acceleration of the driving piston (21; 721), the guiding surface (30; 780) has an asymmetrical path deviating from a sine curve arranged in a peripheral direction substantially in the form of a strip on the driving sleeve (28; 728).

4. A machine according to one of claims 1 to 3, characterised in that, the number of alternating curve maxima (32; 732) and curve minima (33; 733) of the guiding surface (30; 780) is so selected that three, in particular, axial impacts can be applied to the striker (23; 723) and thus to the tool (19; 719) for each complete revolution of the rotary driving sleeve (28; 728) or enforced mounting (335; 435; 535).

5. A machine according to one of claims 1 to 4, characterised in that, two or preferably three or more rolling or sliding members (31; 782, 783) are provided arranged at the same angular distances from one another in a peripheral direction.

6. A machine according to one of claims 1 to 5, characterised in that, the rolling or sliding members are formed as rollers (782, 783), balls (31), sliders or the like and are preferably made hollow inside.

7. A machine according to one of claims 1 to 6, characterised in that, the enforced mounting (35; 135; 235; 335; 435; 535; 665, 667; 784; 785) is rotationally fixed in the housing relatively to the driving sleeve (Figures 1 to 3, 9) or can be rotated (Figures 4, 5 and 8) and/or can be selectively released for rotation by a clutch (667; 785-789) out of the rotationally fixed position.

8. A machine according to one of claims 1 to 7, characterised in that, the driving sleeve (28) and/or the rotary sleeve (20) and/or the tool receiver (18) are integral with one another or are at least in a fixed rotational driving connection with one another and that they are all arranged coaxial to one another.

9. A machine according to claim 7, characterised in that, the rotationally driven enforced mounting (335; 435; 535) and/or the rotary sleeve (320; 420; 520) and/or the tool receiver (318; 418; 518) are integral with one another or are at least in a rotationally fixed driving connection with one another.

10. A machine according to one of claims 1 to 9, characterised in that, on its end remote from the striker, the driving sleeve (26; 128; 228; 428; 628; 728) has coaxial inner or outer peripheral teeth (453; 791) or a coaxial gear wheel (27; 127; 227; 627), particularly a spur gear or bevel gear, which is rigidly coupled for rotation to the driving sleeve directly (Figures 1, 3 below, 5 below, 6, 9) or through a safety coupling (Figure 3 above) and that the driving motor carries a driving pinion (25; 125; 325; 425) on the motor shaft (26; 126; 326; 426) in which is in engagement with the peripheral teeth or the gear wheel.

11. A machine according to one of claims 1 to 10, characterised in that, the guiding surface is arranged on an axial end surface (779) of the driving sleeve (728) and is formed as an axial cam surface (780) (Figure 9).

12. A machine according to claim 11, characterised in that, the axial cam surface (780) is arranged on a radially projecting annular shoulder (781) arranged on a peripheral portion of the driving sleeve (728) remote from ths striker (723).

13. A machine according to claim 11 or 12, characterised in that, both the striker (723) and the driving piston (721) are arranged sealingly and slidingly and one behind the other within the driving sleeve (728) and the, in particular integral, rotary sleeve (720) fixed for rotation therewith.

14. A machine according to one of claims 11 to 13, characterised in that, the enforced mounting is formed by at least one radial bearing pin (784) which carries at its end a sliding member or a roller rotatable about the axis of the pin and which follows the axial cam surface and that the bearing pin (784) is held against rotation with respect to the housing (710) and by means of its sliding member or the roller (782, 783) can be urged against the axial cam surface (780) preferably by means of an axial compression spring (785).

15. A machine according to claim 14, characterised in that, the bearing pin (784) is formed as a gudgeon pin passing diametrally through the driving piston (721), retained within the latter and provided with sliding members or rollers (782, 783) arranged at each end.

16. A machine according to claim 14 or 15, characterised in that, the bearing pin (784) and the driving piston (721) are non-rotatably supported by the housing (710) by means of the axial compression spring (785) and are preferably releasable selectively for rotation.

17. A machine according to one of claims 11 to 16, characterised in that, the driving sleeve (728) together with an integral rotary sleeve (720) and an integral tool receiver (718) is mounted in the housing (710) on the one hand in the axial region of the tool receiver (718) and the annular shoulder (781) together with an axial cam surface (780) is mounted in the housing (710) on the other hand and each is mounted in the housing by means of a bearing (739 or 778), particularly a non-friction bearing and/or roller bearing.

18. A machine according to one of claims 1 to 10, characterised in that, the guiding surface (30) is arranged on the inner peripheral surface of the driving sleeve (28) (Figures 1 to 8).

19. A machine according to claim 18, characterised in that, the guiding surface is formed as a guiding groove (30) having a substantially circular arcuate groove cross-section and that at least one ball (31), preferably two or three, engaging in the guiding groove (30) is provided as a follower.

20. A machine according to claim 18 or 19, characterised in that, the driving piston (21) is sealingly and slidingly guided within the striker (23) and is formed as a hollow piston particularly as an axial piston sleeve (29) open at one end directed towards the tool receiver (18).

21. A machine according to one of claims 18 to 20, characterised in that, the piston sleeve (29; 629) has on the outer peripheral surface a driving surface (34 or 665, 666), especially an annular groove, on which or in which the at least one ball (31 or 663, 664) engages as a follower (Figures 1 to 5, 8 or Figure 6).

22. A machine according to one of claims 18 to 21, characterised in that, the enforced mounting is formed by a guiding sleeve (35) which, for each ball (31), includes a guiding slot (36) extending at least substantially axially and within which the ball (31) is retained in a substantially cage-like manner but is movable in a direction in which the guiding slot (36) extends (Figures 1 to 5, 8).

23. A machine according to claim 22, characterised in that, for the better adaptation of the to and fro movement, speed and acceleration of the driving piston (21; 721) the guiding slot (36) provided for each ball (31) is arranged at an acute angle inclination or is made curved with respect to an imaginary axial surface line of a cylinder.

24. A machine according to claim 22 or 23, characterised in that, the guiding sleeve (35) extends coaxially with respect to the hollow piston (21) and the piston sleeve (29) and surrounds the latter concentrically and guides the latter in its interior (Figures 1 to 5, 8).

25. A machine according to one of claims 22 to 24, characterised in that, the driving sleeve (28) surrounds the guiding sleeve (35) with radial clearance and at least over the axial length over which the at least one guiding slot (36) extends and that each ball (31) forcedly guided in a guiding slot (36) engages on the one hand in the guiding groove (30) and on the other hand in the annular groove (34) in a radial direction through the guiding slot (36).

26. A machine according to one of claims 18 to 25, characterised in that, the rotary sleeve (20) is coupled for rotation with the tool receiver (18) and is mounted in the housing (10) in the coupling region (Figures 1 to 9).

27. A machine according to one of claims 22 to 26, characterised in that, the rotary sleeve (20; 120; 220; 620; 720) is integral with the driving sleeve (28; 128; 228; 628; 728) and at the end remote from the tool receiver the driving sleeve is rotatably mounted, preferably on the guiding sleeve (35; 135; 235; 435; 535) and through its gear wheel is in meshing engagement with a driving pinion on the motor shaft.

28. A machine according to one of claims 22 to 27, characterised in that, the guiding sleeve (35; 135; 235) is supported in the housing against rotation (Figures 1 to 3).

29. A machine according to one of claims 22 to 27, characterised in that, the rotary sleeve (320; 420; 520) is connected to the guiding sleeve (335; 435; 535) for rotation therewith and the guiding sleeve (335; 435) is rotatably mounted in the housing and carries a driving gear wheel (327; 427) in which is in engagement with a driving pinion (325; 425) on the motor shaft (326; 426) (Figures 4 and 5).

30. A machine according to claim 29, characterised in that, the driving sleeve (328; 428) is supported in the housing against rotation by a switchable frictionally or positively acting clutch (350; 454-459) but is releasable for rotation (Figures 4 and 5).

31. A machine according to claims 29 and 30, characterised in that, the driving sleeve (428) arranged against rotation by means of the clutch (454-459) but rotatable on releasing the clutch is coupled to a gear wheel (453) which, together with the driving gear wheel (427) of the driven guiding sleeve (435), is in engagement with the driving pinion (425) on the motor shaft (426) but is preferably driveable in the opposite sense to the driving gear wheel (427) of the driven guiding sleeve (435).

32. A machine according to one of claims 18 to 21, characterised in that, on its outer peripheral surface, the piston sleeve (629) is provided with a radially recessed ball pocket (665 and 666) as a driving surface for each ball and within which each ball is coupled to the driving piston (621) as an enforced mounting in an axial direction and non-displaceable in a peripheral direction and that, by means of a switchable clutch (667), the driving piston (621) in its turn is maintained against rotation with respect to the housing (610) or is rotatable relatively to the housing (610) together with the driving sleeve (628) with the clutch (667) released (Figure 6).

33. A machine according to claim 32, characterised in that, the clutch (667) has a central ball cage (673) with coupling balls (674) held therein, axially parallel or even undulating to some extent ball grooves (675) on the driving piston (621) for engagement with a respective coupling ball (674) and an external switching ring (676) which on its inner surface has receiving pockets (677) for each coupling ball (674) and into which the coupling balls (674) extending radially out of the ball grooves (675) can be received with the coupling released (Figure 7C).

34. A machine according to claim 33, characterised in that; the central ball cage (673) of the clutch (667) is held against rotation in the housing (610) and supports the driving piston (621).

35. A machine according to one of claims 1 to 34, characterised in that, the motor shaft together with the driving pinion is aligned axially parallel with or at an angle to the longitudinal axis of the driving piston (Figures 2 to 9 or Figure 1).

36. A machine according to one of claims 1 to 35, characterised in that, at the end facing the striker (23) the tool receiver (18) has an internal trap device (40) for the striker (23) in its extended idling position.

37. A machine according to claim 36, characterised in that, the trap device has a clamping ring (40) particularly an 0 ring, within the tool receiver (18) and an annular shoulder (41) on the striker (23) provided with radially inclined shoulders (42, 43) on each side in an axial direction.

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