EP0401548B1 - Device for a screw fastening tool - Google Patents

Description

The invention relates to a power-driven screwing machine tool with a drive arranged in a housing, with a screwing tool which is connected to a tool drive shaft which is axially displaceable relative to the housing, and with a screw-in depth switch-off, comprising a depth stop which defines a screw-in depth and is held on the housing and between the drive and the coupling of the tool drive shaft and by axial displacement of the tool drive shaft from a rest position in the direction of the drive into a working position coupling, which has a coupling element driven by the drive and a coupling element connected to the tool driving shaft as well as an intermediate coupling element arranged between these coupling elements, the intermediate coupling element having a first of the coupling elements, the intermediate coupling element from a load-free position to the other, second cup in the event of a load Plungselement to driving clutch axially shifting in a load position and maintaining a torque transmission and with the second coupling element forms a release clutch which interrupts a torque transmission when the screw-in depth is reached.

Such a power-driven screwing machine tool is known, for example, from EP-A-0 195 853 and also from DE-PS 36 37 852. The clutch works in such a way that when the screw-in depth defined by the depth stop is reached, the clutch triggers and switches off without chattering. Screwing machine tools of this type are mainly used as construction screwdrivers, since a large number of screws with a constant screwing depth are to be screwed in in drywall construction.

However, it is not possible with such a screwing machine tool with screw-in depth switch-off to accomplish those screwdriving cases in which two parts are to be screwed together with a predeterminable torque, for example two sheets which are at a short distance from one another are pulled against one another by the screw with a predetermined torque and thus to Plant should be brought.

The invention is therefore based on the object of improving a screwing machine tool in such a way that, in addition to a screw-in depth switch-off, it also has a screw-in torque switch-off.

This object is achieved according to the invention in a screwing machine tool of the type described at the outset by that the screw-in depth switch-off can be switched over to a screw-in torque switch-off incorporating the release clutch as a torque-limiting element.

The essence of the present invention thus shows that the screw-in depth switch-off, which normally interrupts the torque transmission only when the preset screw-in depth is reached, regardless of the counter torque that occurs, can be switched over to a screw-in torque switch-off, the trigger coupling of the screw-in depth switch-off being used as the torque-limiting element, although the release clutch does not primarily have the function of limiting the torque when the screw-in depth is switched off.

The advantage of the solution according to the invention can be seen in the fact that the possibility was created in a structurally very simple manner to operate one and the same screwing machine tool in two different operating modes and thus to handle different types of screwing.

In the basic principle of the invention, it was not specified to what extent the driving clutch during the switching process is involved. It would be possible, for example, to make a gear train bypassing the driving clutch switchable, so that the driving clutch as such is switched on or off. In terms of construction, it has proven to be particularly simple and expedient if the driving clutch can be blocked against a load-dependent axial displacement of the intermediate coupling element in the direction of the first coupling element when the triggering clutch is triggered.

The advantage of this solution is to be seen in the fact that only a partial functional blocking of the driving clutch is required to achieve the solution according to the invention. The driving clutch is always to be understood in the sense according to the invention in such a way that it does not come loose when the torque transmission is interrupted, but always remains in engagement, but permits an axial displacement of the intermediate coupling element relative to the first coupling element.

In principle, the driving clutch could be blocked in all intermediate positions including the load-free and the load position of the same. However, it is particularly easy to block the driving clutch if the driving clutch can be blocked against a load-dependent axial displacement of the intermediate coupling element when the release clutch is triggered in the load-free position or the load position, since these two positions are easiest to define as defined positions.

It has proven to be particularly advantageous if the driving clutch can be blocked in the load-free position, since in this position there has been no axial displacement of the intermediate coupling element away from the first coupling element and thus there is a space-saving, compact arrangement of the intermediate coupling element relative to the first coupling element.

To achieve the coupling effect, it is expedient if a blocking element which can be adjusted between an effective position blocking the driving clutch and an inactive position is provided.

The blocking element is advantageously designed such that it can be actuated from outside the housing.

Since in the construction according to the invention, switching from the screw-in depth switch-off to the screw-in torque switch-off should preferably be possible in all possible rotational positions, it is expediently provided that the blocking element is inactive in an effective position when the clutch is in the rest position and by moving the clutch from the rest position to the working position can be activated. As a result, the blocking element does not initially intervene in the rest position, and it is only when the clutch is moved into the working position that the blocking element is activated at the same time. Thus, for example, the elements of the driving clutch can still be freely rotated in the rest position, which can be used to let the blocking element become active in its effective position when the clutch is moved into the working position.

Since, as described at the beginning, the depth stop is an element of the screw-in depth switch-off and is not necessary for the function of the screw-in torque switch-off, it has proven to be advantageous in a preferred embodiment if the depth stop can be brought into an ineffective position.

A particularly favorable solution provides for the depth stop to be in the ineffective position when the driving clutch is blocked, that is to say that the ineffective position of the depth stop is coupled with the blocking of the driving clutch in the manner according to the invention described above.

If such a coupling is advantageous and desirable, it can then be used in a further development of this exemplary embodiment so that the blocking element can be actuated by means of the depth stop, so that when the depth stop is brought into its ineffective position, this handling also actuates the blocking element represents.

In order to make it clear to the user in which operating mode the screwing machine tool according to the invention is currently operated, it is extremely expedient if the depth stop is held pluggable on the housing and if the blocking element is ineffective when the depth stop is plugged in and effective when the depth stop is removed Position. In that in this embodiment, a scan to that effect If the depth stop is attached or not, and this scanning is used at the same time for actuating the blocking element, a particularly safe handling solution is achieved.

Since the release clutch in the solution according to the invention is primarily designed to switch off in connection with the screw-in depth shutdown at a certain screw-in depth and not when a limit torque is exceeded, there are particular advantages in the solution according to the invention if an adjusting device is provided for adjusting a release characteristic of the release clutch , so that the release clutch can be adjusted to the desired switch-off characteristic, in particular with the screw-in torque switch-off, via this adjusting device.

In order to make this possible for the operator in a simple manner, it is provided that the adjusting device can be adjusted by an actuating element accessible from outside the housing, so that the operator has easy access to the adjusting device while working.

In the exemplary embodiments described so far, it has not been specifically dealt with which characteristic features of the release clutch should be adjustable. It has proven to be particularly expedient in the context of a preferred embodiment if the triggering torque of the triggering clutch can be adjusted with the adjusting device and thus a simple adaptation of the triggering clutch to the individual desired triggering torques is possible.

In the context of the exemplary embodiments described above, it is particularly advantageous if the coupling elements and the intermediate coupling element are arranged on one axis. It is preferably even provided that the coupling elements and the intermediate coupling element are arranged coaxially to the tool drive shaft, a structurally particularly simple solution providing that the coupling elements and the intermediate coupling element are arranged on the tool drive shaft, but at least then the intermediate coupling element and the second coupling element are displaceable relative to the latter have to be.

In the exemplary embodiments described so far, nothing was said about how the driving clutch should be designed. It has proven to be particularly advantageous if the driving clutch has at least one footprint, which has an incline to the axis of the coupling elements, which acts on a counter surface when the first coupling element and the intermediate coupling element rotate relative to one another, and the intermediate coupling element in the axial direction from the load-free position shifts to the load position. In a drive coupling designed in this way, the axial displacement is triggered by a relative rotation between the first coupling element and the intermediate coupling element, which can be easily achieved in the torque transmission according to the invention when the screw-in depth is switched off.

The arrangement of the footprint can be done in any way. So it is conceivable, for example, that a guide surface running with a corresponding slope is used as the supporting surface is provided for a ball as a connecting element between the first coupling element and the intermediate coupling element. But it is also conceivable that the footprint is formed by a backdrop on which a scanning pin slides, the slide track can in the simplest case be an inner edge of a bore on which a pin slides with a much smaller diameter than the bore. The footprint can be realized particularly easily if it is designed as the side edge of a claw.

In order to limit the relative rotation of the above-described footprint, it is provided that the relative rotation between the first coupling element and the intermediate coupling element is limited by a stop surface which is effective in the load position. The stop surface preferably extends transversely to the footprint. If claws are used as connecting elements between the first coupling element and the intermediate coupling element, the stop surface can be designed such that it is a side surface of the claw that is parallel, in particular, to the axis of the coupling elements.

Particularly structurally simple solutions of a claw coupling using connecting elements provide that the first coupling element and the intermediate coupling element have claws with identically oriented side surfaces. In addition, it is also advantageous if the claws have identically oriented side flanks.

In the simplest case, this means that the claws of the first coupling element and the intermediate coupling element are identical to one another.

In all cases in which the driving clutch is to be blocked in the load-free position, it is expedient if the driving clutch in the load-free position positions the first coupling element and the intermediate coupling element relative to one another, in particular with respect to a relative rotation thereof. A blocking of the two elements can thus be achieved in a simple manner, whereas if the elements of the driving clutch in the load-free position were not defined, this would only be possible with additional aids that position the two elements.

This positioning can be achieved particularly easily in terms of construction if the side flanks of successive claws of the intermediate coupling element or of the first coupling element center the claw of the first coupling element or of the intermediate coupling element engaging between them in the defined load-free position.

In all the exemplary embodiments, in which the driving clutch is designed so that it requires an inclined surface to generate the axial displacement of the intermediate coupling element during the transition from the no-load position to the load position, it is necessary for the coupling to function that the intermediate coupling element points in the direction its no-load position is spring-loaded, in particular a spring that presses it apart is provided between the second coupling element and the intermediate coupling element. In the latter case, a further advantageous effect is achieved simultaneously with this spring that the first coupling element is spring-loaded in the direction of a load-free position.

In the exemplary embodiments described so far, no comments have yet been made about the release clutch. It is structurally very simple if the release clutch is formed by cams which are arranged on the intermediate coupling element and the second coupling element and face one another.

The cams are preferably arranged on a circular path around the axis of the intermediate coupling element. Furthermore, it is particularly advantageous in order to achieve an easy engagement of the cams while the machine is running if the gaps between the cams are a multiple of a cam width, so that the respective opposite cam can dip into the gaps between the cams in a simple manner.

If the driving clutch according to the invention is designed in such a way that a footprint with a slope is provided, which brings about the axial displacement when the intermediate coupling element rotates relative to the first coupling element, then it is particularly expedient to carry out the switchover according to the invention to a screw-in torque switch-off if the blocking element blocked the relative rotation of the intermediate coupling element to the first coupling element. In particular, the easiest way to achieve this is that the blocking element blocks the relative rotation in the load-free position.

A large number of variants are conceivable with regard to the design of the blocking element. For example, it would be possible for the blocking element to non-positively block the driving clutch. However, it is particularly expedient if the coupling ring in its active activated position blocks the intermediate coupling element and the first coupling element in a rotationally fixed manner, the positive locking elements preferably running parallel to the axis of the intermediate coupling element and the first coupling element.

It is particularly simple in this case if the coupling ring has grooves with which wedges of the intermediate coupling element and the first coupling element can be brought into engagement, the grooves and the wedges preferably running parallel to the axis with their longitudinal direction in order to move the coupling ring parallel to the axis to enable.

In the exemplary embodiments described so far, nothing has been said about how the intermediate coupling ring should advantageously be mounted and guided. A solution has proven to be particularly simple and expedient in which the coupling ring in its effective and ineffective position is guided coaxially to the intermediate coupling element.

The simplest way of arranging the coupling ring provides that it in its inactive position with the coupling in the working position protrudes over the intermediate coupling element in the direction of the second coupling element and thus no engagement of the wedges of the first coupling element in the coupling ring is possible. In contrast, the coupling ring projects in its effective position when the coupling is in the working position via the intermediate coupling element in the direction of the first coupling element, so that the wedges of the first coupling element engage in the grooves of the coupling ring.

It has proven to be a particularly preferred solution if the blocking element is spring-loaded in the direction of one of its two positions, so that displacement of the blocking element into one of its two positions is possible only by acting on it in one direction against the force of the spring.

It is particularly advantageous here if the blocking element is spring-loaded in the direction of its effective position, so that it can be moved with an adjusting element in the direction of its inactive position. The spring action in the direction of the active position has the further advantage that indenting the positive connection between the first coupling element and the blocking element is facilitated by the fact that the blocking element can initially move in the direction of its ineffective position if the positive connection is not suitable, but immediately afterwards a fit of the positive connection engages it and the blocking element changes into its effective position.

In order to obtain a defined position of the tool drive shaft when the main tool is placed on the screw, it is advantageous if the axial displacement of the tool drive shaft in the direction of the drive can be limited by a rear stop position. The rear stop position is preferably formed by an axial bearing between the tool drive shaft and the housing, the axial bearing in particular being arranged on an end of the tool drive shaft opposite the screwing tool.

In one embodiment of the solution according to the invention, in which the connection between the intermediate coupling element and the second coupling element takes place by means of cams, it is advantageously provided that an engagement depth of the cams of the release clutch can be adjusted with the adjusting device.

The depth of engagement of the cams can be varied by moving different parts. For example, it would be conceivable to vary the distance between the intermediate coupling element and the second coupling element. In terms of construction, however, a concept can be implemented in which the distance between the first coupling element and the second coupling element can be changed by the adjusting device when the tool drive shaft is in the rear stop position.

This can also be realized in different ways. For example, it would be possible to adjust the rear stop position of the tool drive shaft shape. However, it is even easier if the second coupling element can be adjusted in the axial direction with the adjusting device.

The structurally most favorable solution provides that the coupling element driven by the drive is displaceable in the axial direction by a displacement device serving as an adjusting device.

The latter solution offers further advantages with regard to its design if the coupling element driven by the drive is supported on the displacement device on its side opposite the coupling element connected to the tool drive shaft.

The displacement device itself can now be designed in a wide variety of ways. For example, the displacement could take place via a spindle element. However, it is easiest if the displacement device comprises two adjusting rings which can be rotated relative to one another.

With these adjusting rings, a simple axial displacement can be achieved if one adjusting ring has a sliding surface that extends with an incline to the axis of rotation of the relative rotation, on which the other adjusting ring rests with a supporting surface, wherein the supporting surface itself can also be designed as a sliding surface.

The relative rotation can be achieved most simply in that one of the adjusting rings is rotatably mounted on the housing and the other adjusting ring is rotatable.

A rotary device is advantageously provided for rotating the rotatably mounted adjusting ring.

An actuating element which can be actuated from outside the housing is provided for actuating the rotating device.

As already mentioned in connection with a previous exemplary embodiment, the actuating element for the adjusting device should be accessible from outside the transmission housing. For this reason, this actuating element must be guided out of the gear housing by the adjusting device. Problems then arise when the actuating element is led out of a transmission housing section of the housing, since the transmission housing is filled with lubricant and therefore a hermetic seal is necessary in order to prevent lubricant from escaping from the transmission housing section and on the other hand to prevent dirt from entering the transmission housing section to prevent. For this reason, it is expedient if the actuating element is led out of the housing outside of a transmission housing section. Within the scope of the screwing machine tool according to the invention, it is advisable here if the actuating element is preferably led out of a motor housing section of the housing.

In the simplest case, it is provided that the actuating element acts on the rotatable adjusting ring via an intermediate member. However, it is even more advantageous if the intermediate member is passed through a wall between the gear housing section and the motor housing section.

In order to find a constructive solution in which the shortest possible paths from the actuator to the adjustment device can be reached, it is advantageous if the adjustment device is mounted on the wall between the gear housing section and the motor housing section.

Furthermore, particularly when the intermediate member is passed through the wall between the transmission housing section and the motor housing section, a solution is favorable in which the adjusting ring supporting the coupling element driven by the drive is rotatably fixed and the adjusting ring arranged on the opposite side of the coupling element is rotatably arranged.

However, this is not intended to preclude a solution in which the adjusting ring supporting the drive element driven by the drive is rotatable and the other adjusting ring is arranged in a rotationally fixed manner.

The adjusting device is expediently dimensioned such that it allows the distance between the coupling elements to be changed by at least half the height of the cams. It is even more advantageous if the adjusting device allows a change in the distance between the coupling elements in the order of magnitude of the height of the cams.

Fig. 1

eine teilweise aufgebrochene Seitenansicht einer erfindungsgemäßen Schraubwerkzeugmaschine;

Fig. 2 a bis c

einen teilweisen Schnitt durch eine erfindungsgemäße Kupplung bei in unwirksamer Stellung stehendem Blockierungselement;

Fig. 3

eine Draufsicht auf ein erstes Kupplungselement in Richtung der Pfeile 3-3 in Fig.2;

Fig. 4

eine Draufsicht auf ein Zwischenkupplungselement in Richtung der Pfeile 4-4 in Fig. 2;

Fig. 5

eine Draufsicht auf das Zwischenkupplungselement in Richtung der Pfeile 5-5 in Fig.2;

Fig. 6 a bis c

eine teilweise geschnittene Darstellung der erfindungsgemäßen Kupplung bei in wirksamer Stellung stehendem Blockierungselement;

Fig. 7

eine Draufsicht auf einen Stellring einer erfindungsgemäßen Stelleinrichtung;

Fig. 8

eine erste Variante einer Betätigungsmöglichkeit eines Stellrings;

Fig. 9

eine zweite Variante der Verdrehung eines Stellrings;

Fig.10

einen Schnitt längs Linie 10-10 in Fig. 2 und

Fig. 11

eine Draufsicht in Richtung des Pfeils A in Fig. 9.

Further features and advantages of the invention are the subject of the following description and the drawing of an embodiment with variants. The drawing shows:

Fig. 1

a partially broken side view of a screw machine according to the invention;

2 a to c

a partial section through a coupling according to the invention with the blocking element in an inactive position;

Fig. 3

a plan view of a first coupling element in the direction of arrows 3-3 in Figure 2;

Fig. 4

a plan view of an intermediate coupling element in the direction of arrows 4-4 in Fig. 2;

Fig. 5

a plan view of the intermediate coupling element in the direction of arrows 5-5 in Figure 2;

6 a to c

a partially sectioned illustration of the clutch according to the invention with the blocking element in an effective position;

Fig. 7

a plan view of a collar of an actuating device according to the invention;

Fig. 8

a first variant of an actuating possibility of an adjusting ring;

Fig. 9

a second variant of the rotation of an adjusting ring;

Fig. 10

a section along line 10-10 in Fig. 2 and

Fig. 11

a plan view in the direction of arrow A in Fig. 9th

An embodiment of a screwing machine tool according to the invention, shown in FIG. 1, comprises a housing, designated as a whole by 10, in which a drive 12 is held, which comprises an electric motor with a rotor 14, which is seated on a motor shaft 16. A front end of the motor shaft 16 is provided with a drive pinion 18.

This drive pinion 18 drives a gearwheel 20, which is connected to a coupling designated as a whole by 22, via which a tool drive shaft 24 is then ultimately driven, which is oriented such that its axis 26 runs parallel to a motor axis 28 of the motor shaft 16 . A front section 30 of the tool drive shaft 24 opposite the drive 12 has a receptacle 32 into which a screwing tool 34 with a fitting piece 36 arranged at a rear end thereof can be inserted. At a front end opposite the fitting 36, the screwing tool is provided, for example, with a Phillips screwdriver 38.

The tool shaft 24 is in turn rotatable with a middle section 40 adjoining the front section 30 in a bearing sleeve 42 of the housing 10 and is displaceable in the direction of its axis 26. The bearing sleeve 42 is in turn screwed into a cylindrical front part 44 of the housing 10 with an internal thread.

Following the central section 40, a rear section 46 of the tool drive shaft 24 extends toward the drive 12, which section is opposite the central section 40 has a reduced diameter. This rear section 46 40 carries the clutch 22 and is in turn received at its rear end 48 in a radial bearing 50 and is additionally provided with an axial bearing 52 which has a ball 56 held in a rear recess 54 of the tool drive shaft 24, which, however, does not always have the Tool drive shaft 24 is supported on a support surface 58, formed by a metal plate 60, but only when the tool drive shaft is in its rear stop position, as is shown, for example, in FIGS. 6 b and c.

The axial bearing 52 and the radial bearing 50 are supported by a wall 62 which divides the housing 10 into a motor housing section 64 and a gear housing section 66 located in front of this motor housing section, into which the motor shaft 16 projects with the drive pinion 18 and which receives the clutch 22.

On the cylindrical front part 44 of the housing 10, a depth stop designated as a whole can be plugged on, which has a fastening sleeve 70 which fits around the cylindrical front part 44 and which adjoins the screwing tool 34 to form an adjusting sleeve carrier 72, in which one as a whole with 74 designated adjusting sleeve is rotatably and adjustable by a thread 76 in the direction of the axis 26. A front support edge 78 of the depth stop 68 surrounding the screwdriver 38 serves as the stop surface, which ultimately determines a screw-in depth of the screw to be screwed in.

The depth stop 68 itself is arranged together with its adjusting sleeve 74 coaxially with the axis 26. Likewise, the cylindrical front part 44 with its cylindrical outer surface 80 is coaxial with the axis 26.

A rear part 82 of the adjusting sleeve 74 opposite the supporting edge 78 is additionally provided with external grooves 84 which run parallel to the axis 26 and into which a ball 88 engages by an O-ring 86 and is resiliently acted upon by the O-ring 86 in order to lock the rotational positions of the adjusting sleeve 74.

The entire depth stop 68 can be removed from the housing 10, which is possible in that the fastening sleeve 70 can be pulled off in the direction of the axis 26 to the front via the cylindrical front part. The fastening sleeve 70 is locked in place on the cylindrical front part 44 by an O-ring 92, which partially protrudes over an inner surface 90 of the fastening sleeve 70 and is supported in an annular groove in the inner surface 90 and which has the possibility of being incorporated into a cylindrical surface 80 To engage annular groove 94 and thereby fix the fastening sleeve 70 in the direction of the axis 26.

In this fixed position, as can also be seen in particular from FIG. 2, a rear end wall 96 bears against an annular surface 98 of the gear housing section 66 that runs perpendicular to the cylindrical lateral surface 80 and limits it to the rear.

The clutch 22 includes in particular a first clutch element 100, an intermediate clutch element 102 and a second clutch element 104, all of which are seated on the rear section 46 of the tool drive shaft 24. The first coupling element 100 is non-rotatably and non-displaceably connected to the tool drive shaft 24 and bears with a rear side 106 against an annular surface 108 of the transition between the rear section 46 and the central section 40. On the side of the first coupling element 100 assigned to the drive 12, the intermediate coupling element 102 is rotatably and displaceably mounted on the rear section 46 in the axial direction. Likewise, the second coupling element 104 is also rotatable and axially displaceably mounted on the rear section 46 and arranged on the side of the intermediate coupling element 102 associated with the drive 12.

In the illustrated embodiment of the screwing machine tool according to the invention, the second coupling element 104 carries the gear 20, which is driven by the drive pinion 18.

A spring 110 is arranged between the intermediate coupling element 102 and the second coupling element 104, which acts on the intermediate coupling element 102 in the direction of the first coupling element 100 and the second coupling element 104 in the direction of the drive 12.

On its side facing away from the intermediate coupling element 102, the rear side 112 of the second coupling element 104 bears against a first adjusting ring 114, which in turn counteracts presses a second adjusting ring 116. Both adjusting rings 114 and 116 form a displacement device 118, which will be described in detail later. At the same time, the rear adjusting ring 116 forms the radial bearing 50 in that it is held by an annular collar 120 of the wall 62. In addition, the second adjusting ring 116 has such an extension in the direction of the axis 26 that the tool drive shaft 24 is always held radially by the second adjusting ring 116 with its rear section 46 in all possible axial displacement positions.

The clutch 22 can now act in a manner known from EP-A-0 195 853 as a screw-in depth switch-off, which interrupts torque transmission when a screw is screwed in at a preselectable screw-in depth and does not show any rattling of the clutch 22.

For this purpose, the clutch 22 is divided into a driver clutch, formed by the first clutch element 100 and the intermediate clutch element 102, and a release clutch, formed by the intermediate clutch element 102 and the second clutch element 104.

To form the driving clutch, both the first coupling element 100 and the intermediate coupling element 102 have claws 122 and 124, which are in engagement with one another. The claws, as can be seen in particular from FIGS. 2 and 3 and 4, are shaped in such a way that they have an elevation 126 or 128 which faces the intermediate coupling element 102 or the first coupling element 100 and is vertical End faces 130 and 132 extending to the axis 26, the end faces 130 and 132 having side edges 134 and 136 extending in the radial direction to the axis 26. Starting from these side edges 134 and 136, side surfaces 138 and 140 run in the direction of the respective element, that is to say the first coupling element 100 and the intermediate coupling element 102, these side surfaces 138, 140 representing partial surfaces of planes of a plane group passing through the axis 26.

Following the side surfaces 138 and 140, the claws 122 and 124 terminate in side flanks 142 and 144, which have a pitch angle with respect to the axis 26, that is to say at an angle to the end surfaces 130 and 132 and also at an angle the side surfaces 138 and 140, and thereby merge into a support surface 146 and 148, which is aligned parallel to the respective end surface 130 and 132, respectively. The pitch angles between the side flanks 142 and 144 and the axis 26 are preferably identical.

For the function of the driving clutch, it is not necessary that the claws 122 and 124 are of identical design. However, identically shaped claws 122, 124 offer advantages in terms of production technology.

In addition, it is not necessary for the function of the driving clutch that the bearing surfaces 146 and 148 have the same arc length as the end faces 130 and 132. However, in the present exemplary embodiment this offers the advantage, which will be explained later, that the claws 122 and 124 when they are full intermesh by the side flanks adjoining the bearing surfaces 146 and 148 142 and 144 are centered relative to each other and are thus in a defined position.

In the following exemplary embodiment, the triggering clutch is formed between the intermediate clutch element 102 and the second clutch element 104 by cams 150 and 152 which are arranged on sides of the two elements 102, 104 which face one another and which have a cam end face 154 or 156 which is perpendicular to the axis 26 stands and cam flanks 158 and 160 emanating from this cam end face, which also have an incline with respect to the axis 26, that is to say are inclined with respect to the cam end faces 154, 156 (FIG. 5).

Between the cams 150 and 152, the intermediate coupling element 102 and the second coupling element 104 have ring surface segments 162 and 164 standing in a plane perpendicular to the axis 26.

Preferably, three cams 150 and 152 are provided on both the intermediate coupling element 102 and on the second coupling element 104, between which the largest possible gaps remain, the gaps being a multiple of these, based on the arc length of the cam end face 154, 156 (FIG. 2 , 5).

Starting from a rest position, shown in Fig. 2a, the clutch 22 now works in the known manner so that by placing the screwdriver 38 on the screw 121, the tool drive shaft and thus the clutch is transferred from the rest position to the working position. In the rest position, due to the action of the spring 110, the claws 122 and 124 of the first coupling element 100 and the intermediate coupling element 102 are centered relative to one another, that is to say the end faces 130 and 132 lie over the entire surface of the respective opposite bearing surfaces 146 and 148. On the other hand, the intermediate coupling element 102 and the second coupling element 104 are spaced apart by the action of the spring 110 which is greater than the sum of the heights with which the cam end faces 154 and 156 rise above the annular surface segments 162 and 164, respectively, so that the Cams 150 and 152 cannot interlock.

In the working position, the intermediate coupling element 102 is shifted so far in the direction of the second coupling element 104 that the cams 150 and 152 engage fully with one another, that is to say with their cam flanks 158 and 160 abut one another. If the drive 12 is now switched on, a torque is transmitted from the second coupling element 104 to the intermediate coupling element 102, which leads to the cams 150 and 152 remaining in engagement due to the greater slope of the cam flanks 158 and 160, while the claws 122 and 124 due to the smaller slope of the side flanks 142 and 144 of the same, slide against one another until their side surfaces 138 and 140 come into contact with one another. The sliding of the claws 122 and 124 on their side flanks 142 and 144, on the one hand, leads to a relative rotation of the intermediate coupling element 102 with respect to the first coupling element 100 and at the same time, starting from an intermediate coupling element 102 supported on the second coupling element 104, to a slight displacement of the first coupling element 100 together with the tool drive shaft 24 in the direction of the screw 121.

Since the depth stop 68 with its support edge 78 only becomes effective when the screw 121 is screwed in to the required stop depth, the force with which the screwing machine tool according to the invention is placed on the screw 121 becomes as long as the screw 121 has not reached this screw-in depth. the tool shaft 24 is held in the direction of the drive 12 and thus the spring 110 is compressed, so that the cams 150 and 152 are further engaged. The state according to FIG. 2b is maintained until the screw 121 has reached the preselected screw-in depth.

Shortly before reaching the screw-in depth, the support edge 78 of the depth stop 68 sits on a surface of the object into which the screw 121 is to be screwed. As a result, the tool drive shaft 24 will move forward with increasing screw-in depth in the direction of the screw, and the spring 110 will ensure that the cams 150 and 152 remain engaged with an ever smaller screw overlap as the screw-in depth increases. The screw-in depth is reached when the cams 150 and 152 with their cam end faces 154 and 156 have the possibility of sliding over one another. At this moment, however, the torque transmitted to the intermediate coupling element 102 ceases to exist, so that, due to the action of the spring 110, the intermediate coupling element 102 reverses the relative rotation to the first coupling element 100 that was initially carried out in the working position in that the claws 122 and 124 on side flanks 142 and 144 slide back into the position they have in their starting position. This removes the cam 150 by an additional distance from the cam 152 and thus prevents the clutch 22 from rattling, which would otherwise occur if the cams 150 and 152 hit each other. With the interruption of the torque transmission to the intermediate coupling element 102, the torque transmission to the screw 121 is also omitted, so that the desired interruption of the screwing process occurs at the screwing depth.

Since not only a screw depth switch-off should now be possible, but also a switchover to a torque switch-off, in which disengagement of the cams 150 and 152 with rattling thereof is desired, the coupling 22 is provided with a coupling ring 170, which is once in an inactive position Pins 172 is held (Fig. 2) so that the clutch 22 can function as previously described. The pins 172 are acted upon by the lower end wall 96 of the fastening sleeve 70 in the plugged-on state and hold the coupling ring 170 in a position in which it encompasses the intermediate coupling element 102 and is also held coaxially to the axis 26 by this, but from the intermediate coupling element 102 in the direction of the second coupling element 104 protrudes, the cams 150 and 152 being arranged such that they lie within the coupling ring 170. Furthermore, the union ring is acted upon in its inactive position by a spring 174 in the direction of its active position. The spring 174 encompasses the coupling ring 170 and is supported on the one hand on the second coupling element 104 and, on the other hand, acts on an annular flange 176 which extends radially outward from the coupling ring 170. The coupling ring 170 is also held in the inactive position by the pins 172 in that these act on the annular flange 176 against the force of the spring 174.

If the depth stop 68 is now removed, there is no action on the pins 172 through the rear end wall 96 of the fastening sleeve 70, so that the pins 172, which are mounted in a bore 178 of the gear housing section 66, can move forward until they reach one in the cylindrical front part 44 incorporated boundary surface 180. The thrust ring 170 is also pushed into its effective position by the force of the spring 174, which is shown in FIG. 6.

In this effective position, the coupling ring 170 is still guided and held concentrically to the axis 26 by the intermediate coupling element 102. However, the coupling ring 170 is displaced so far forward in the direction of the first coupling element 100 that in the rest position of the coupling 22, that is to say with the tool drive shaft 24 displaced completely forwards, a front end face 182 of the coupling ring 170 closes with the contact surface 148 of the intermediate coupling element 102 , that is, does not project beyond it in the direction of the first coupling element 100. In this position, the coupling ring 170, held by the pins 172 and acted against by the spring 174, remains, as shown in FIGS. 6a to c.

In order to serve as a blocking element for the driving clutch between the first coupling element 100 and the intermediate coupling element 102 and a relative rotation of the intermediate coupling element 102 relative to the first coupling element 100 during the transition from the no-load position, shown in FIGS. 2a and 6a, to the load position, shown in FIGS 2b and c, to prevent the collar 170 on one inner circumferential surface 184 (FIG. 4) with grooves 186 running in the direction of the axis 26. Wedges 188 projecting radially outward from the intermediate coupling element 100 positively engage in these grooves 186, so that the coupling ring 170 is held on the intermediate coupling element 102 in a rotationally fixed manner.

Due to the alignment of the grooves 186 and wedges 188 in the axial direction, the coupling ring 170 can also be displaced parallel to the axis 26.

In the same way as the intermediate coupling element 102, the first coupling element 100 also has wedges extending radially outwards, which have the same shape as the wedges 188, so that the coupling ring 170, starting from the intermediate coupling element 102, also engages with the wedges 190 in a rotationally fixed manner is feasible.

According to the invention, the wedges 188 are arranged relative to the claws 124 and the wedges 190 relative to the claws 122 such that the wedges 190 can then be brought into engagement with the grooves 186 in the coupling ring 170, in the grooves of which the wedges 188 already engage, if the claws 124 and 122 are in their load-free position according to FIGS. 2a and 6a, that is to say in a position in which the claws 122, 124 are held centered by the respective side flanks 142, 144 of the respective other claw.

Starting from the rest position of the clutch 22, in which the claws 122, 124 are in their load-free position, and the effective position of the coupling ring 170, shown in FIG. 6a, now placing the screwing tool 34 on the screw 121 leads to the tool drive shaft 24 being displaced rearwards in the direction of the drive 12 and thus also the clutch 22 from its rest position to it Working position is shifted.

Since the first coupling element 100 and the intermediate coupling element 102, starting from the rest position, are in the load-free position of the claws 122 and 124 and no torque applied to them by the drive torque, the first coupling element 100 and the intermediate coupling element 102 are displaced in the direction of the drive 12 to ensure that the wedges 190 of the first coupling element 100 slide into the grooves 186 of the coupling ring 170 and thus block a relative rotation of the intermediate coupling element 102 to the first coupling element 100 before the cams 150 of the intermediate coupling element 100 with the cams 152 of the second coupling element 104 in Can engage and thus torque transmission takes place. The driving clutch between the first coupling element 100 and the intermediate coupling element 102 is thus blocked, so that these two act as a single coupling element, which together with the second coupling element 104 forms the torque cut-off, which triggers when a maximum torque is exceeded, this maximum torque depending on the gradient of the Cam flanks 158, 160, which depend on the force exerted by the screw 121 on the tool drive shaft 24 in the direction of the drive 12 and an engagement height E of the cams 150 and 152.

This engagement height E is set via the adjustment device 118 already mentioned, which comprises the first adjusting ring 114 and the second adjusting ring 116. The two adjusting rings 114 and 116 each have, as shown in FIG. 7 using the example of the adjusting ring 114 on mutually facing end faces 194, adjustment wedges 196 rising from these end faces 194, which comprise a sliding surface 198 which rises obliquely to the end face 194 and which with respect to one another Axis of rotation of the same and thus in the illustrated embodiment has an incline with respect to the axis 26.

The two adjusting rings 114, 116 can be in an initial position such that the respective sliding wedge 196 of one adjusting ring 114 rests on the respective end face 194 of the other adjusting ring 116 and vice versa. By relative rotation of the adjusting rings 114, 116, the adjusting wedges 196 can come into contact with one another, so that the sliding surfaces 198 slide on one another and consequently press the two adjusting rings 114, 116 apart. This is possible until a maximum displacement of the adjusting rings 114, 116 relative to one another has been reached, in which case the adjusting wedges 196 with the highest elevations of the displacement surfaces 198 are in each case above the respective end face 194.

The position in which the adjusting rings 114, 116 have reached the maximum displacement is shown in FIG. 6b. The maximum displacement is chosen so that the engagement height of the cams 150, 152 is maximum, that is to say essentially corresponds to a height of the cams.

The initial position of the rings 114, 116 is shown in FIG. 6c, the difference in the displacement path between the maximum displacement and the initial position corresponding to the difference between the maximum engagement height E of the cams 150, 152 and the minimum engagement height E of the cams 150, 152. At a minimum engagement height E, shown in FIG. 6c, the cams engage with one another only with their regions of the cam flanks 158, 160 which directly adjoin the respective cam end faces 154, 156.

The rotation of the adjusting rings 114, 116 relative to each other can be done in the simplest case by the fact that, as shown in FIG Extending lever 200, which passes through an opening 202 of the gear housing section 66 and has a handle part 204 lying outside the same. The opening 202 is dimensioned so that a pivoting angle of the lever 200 causes a relative rotation of the adjusting rings 114, 116 from the starting position to the position with maximum displacement. The opening 202 is preferably also provided with latching bumps 203, with which the lever 200 can be locked in different positions.

An alternative preferred according to the invention of this simple embodiment of a possibility for rotating the adjusting rings 114, 116 relative to one another is shown in FIGS. 9, 10 and 11. In this embodiment, in contrast to the embodiment mentioned above, the first adjusting ring 114 is held on the wall 62 in a rotationally fixed manner. This is preferably done by two retaining pins 206 with circular cylindrical heads 208, which are arranged with respect to the axis 26 on opposite sides of the first adjusting ring 114 so that the heads 208 engage with their outer circumference 210 in recesses 214 formed in an outer jacket 212 of the first adjusting ring 114 corresponding to the outer circumference and thereby prevent the first adjusting ring 114 from rotating.

The second adjusting ring 116 is enclosed by an annular bead 216 formed on the wall 62 and is rotatably supported in the wall 62 by this annular bead. From this second adjusting ring 116, on its end face 218 opposite the first adjusting ring 114, a pivot pin 220 protrudes, which passes through the wall 62 in a region 222 lying within the annular bead 216 and projects beyond the wall 62 into the motor housing section 64.

The pivot pin 220 is preferably aligned parallel to the axis 26.

Arranged in the motor housing section 64 is a slide 224 which extends through it transversely to the axis 26 and which has a recess machined in the form of a receptacle 226 for the pivot pin 220. The pivot pin 220 is arranged such that the slide 224 with the receptacle 226 can be displaced approximately tangentially to the arc segment 230, on which the pivot pin 220 runs from the initial position to the position of the maximum displacement when the adjusting rings 114, 116 are rotated relative to one another. The displacement direction 228 of the slide 224 is preferably parallel to an upper housing surface 232.

Around the slide 224 in different positions, in particular also in intermediate positions between the starting position and the position of the maximum displacement to be able to fix, a locking element in the form of a spring-loaded locking ball 234 is provided in the slide 224, which is pressed by a spring 236 against a locking plate 238, which has locking slots 240 running parallel to one another and transverse to the direction of displacement 228 and is firmly anchored to the wall 62 on the side facing the slider 224, the slider 224 resting against the locking plate 238 with a front side 242 and the locking ball 234 projecting beyond the front side 242.

Preferably, the slide 224 has two handle parts 244 and 246 projecting on opposite sides of the housing, the slide being dimensioned such that in the initial position of the adjusting rings 114, 116 one handle part 244 and in the position of maximum displacement the other handle part 246 neighboring areas of the housing 10 laterally protrudes.

A particularly favorable exemplary embodiment is advantageously designed such that the slide 224 does not protrude over an overall contour of the housing in any position.

The sliding device 118 can thus be adjusted by the slider 224, so that the tripping characteristic of the tripping clutch between the intermediate coupling element 102 and the second coupling element 104 can be adjusted with an effective coupling ring 170, and thus the screwing machine tool according to the invention, in addition to a screw-in depth switch-off with depth stop, which triggers without rattling, a torque switch-off with adjustable trigger characteristic.

Claims (40)

1. Power-operated screwdriving machine tool, with a drive (12) arranged in a housing (10), with a screwdriving tool (34) which is connected to a tool drive shaft (24) axially displaceable relative to the housing (10), and with a screw-in depth cut-off comprising a depth stop (68) determining a screw-in depth and held on the housing as well as a coupling (22) which is arranged between the drive (12) and the tool drive shaft (24) and can be transferred, as a result of axial displacement of the tool drive shaft, from a position of rest in the direction of the drive (12) into a working position and which has a coupling element (104) driven by the drive (12) and a coupling element (100) connected to the tool drive shaft (24) as well as an intermediate coupling element (102) arranged between these coupling elements,the intermediate coupling element (102) forming, with the first of the coupling elements (100), a take-up coupling (100, 102), which, in the event of load, axially displaces the intermediate coupling element (102) from a load-free position towards the other second coupling element (104) into a load position and maintains a torque transmission, and, with the second coupling element (104), a release coupling (102, 104) which interrupts a torque transmission when the screw-in depth is reached, characterised in that the screw-in depth cut-off can be changed over to a screw-in torque cut-off which incorporates the release coupling (102, 104) as a torque-limiting element.
2. Screwdriving machine tool according to Claim 1, characterised in that the take-up coupling (100, 102) can be blocked against a load-dependent axial displacement of the intermediate coupling element (102) in the direction of the first coupling element (100) during the release of the release coupling (102, 104).
3. Screwdriving machine tool according to Claim 2, characterised in that the take-up coupling (100, 102) can be blocked in the load-free position or the load position against a load-dependent axial displacement of the intermediate coupling element (102) during the release of the release coupling (102, 104).
4. Screwdriving machine tool according to Claim 2 or 3, characterised in that a blocking element (170) adjustable between an effective position blocking the take-up coupling (100, 102) and an ineffective position is provided.
5. Screwdriving machine tool according to Claim 4, characterised in that the blocking element (170) can be actuated from outside the housing.
6. Screwdriving machine tool according to Claim 4 or 5, characterised in that in the effective position, with the coupling (100, 102, 104) being in the position of rest, the blocking element (170) is inactive and can be activated by transferring the coupling (100, 102, 104) from the position of rest into the working position.
7. Screwdriving machine tool according to one of the preceding claims, characterised in that the depth stop (68) can be brought into an ineffective position.
8. Screwdriving machine tool according to Claim 7, characterised in that, with the take-up coupling (100, 102) blocked, the depth stop (68) is in the ineffective position.
9. Screwdriving machine tool according to Claim 8, characterised in that the blocking element (170) can be actuated by means of the depth stop (68).
10. Screwdriving machine tool according to Claim 9, characterised in that the depth stop (68) is held attachably on the housing (10), and in that the blocking element (170) is in its ineffective position, with the depth stop (68) attached, and in its effective position, with the depth stop (68) removed.
11. Screwdriving machine tool according to one of the preceding claims, characterised in that an adjusting device (118) for adjusting a release characteristic of the torque cut-off (102, 104) is provided.
12. Screwdriving machine tool according to Claim 11, characterised in that the adjusting device (118) can be adjusted by means of an actuating element (224) accessible from outside the housing (10).
13. Screwdriving machine tool according to Claim 11 or 12, characterised in that the release torque of the release coupling (102, 104) can be adjusted by means of the adjusting device (118).
14. Screwdriving machine tool according to one of the preceding claims, characterised in that the take-up coupling (100, 102) has at least one regulating face (142, 144) which is arranged with a pitch relative to the axis (26) of the coupling elements (100, 102) and which, during a relative rotation between the first coupling element (100) and the intermediate coupling element (102), acts on a counterface (144, 142) and displaces the intermediate coupling element (102) in the axial direction from the load-free position into the load position.
15. Screwdriving machine tool according to Claim 14, characterised in that the regulating face is designed as a side flank (142, 144) of the claw (122, 124).
16. Screwdriving machine tool according to Claim 14 or 15, characterised in that, in the load-free position, the take-up coupling (100, 102) positions the first coupling element (100) and the intermediate coupling element (102) specifically relative to one another, especially in terms of a relative rotation of these.
17. Screwdriving machine tool according to Claim 16, characterised in that the side flanks (142, 144) of successive claws (124, 122) of the intermediate coupling element (102) or of the first coupling element (100) centre the claw (122, 124), engaging between these, of the first coupling element (100) or of the intermediate coupling element (102) in the specific load-free position.
18. Screwdriving machine tool according to one of the preceding claims, characterised in that the intermediate coupling element (102) is spring-loaded in the direction of its load-free position.
19. Screwdriving machine tool according to one of the preceding claims, characterised in that the release coupling (102, 104) comprises mutually confronting bosses (150, 152) arranged on the intermediate coupling element (102) and on the second coupling element (104).
20. Screwdriving machine tool according to one of Claims 14 to 19, characterised in that the blocking element (170) blocks a relative rotation of intermediate coupling element (102) in relation to the first coupling element (100).
21. Screwdriving machine tool according to Claim 20, characterised in that the blocking element is a union ring (170) for the intermediate coupling element (102) and for the first coupling element (100).
22. Screwdriving machine tool according to Claim 21, characterised in that, in its effective activated position, the union ring (170) fixes the intermediate coupling element (102) and the first coupling element (100) fixedly in terms of rotation by positive connection.
23. Screwdriving machine tool according to Claim 21 or 22, characterised in that, in its effective and ineffective positions, the union ring (170) is guided by the intermediate coupling element (102) coaxially relative to the latter.
24. Screwdriving machine tool according to one of Claims 4 to 23, characterised in that the blocking element (170) is spring-loaded in the direction of one of its two positions.
25. Screwdriving machine tool according to Claim 24, characterised in that the blocking element (170) is spring-loaded in the direction of its effective position.
26. Screwdriving machine tool according to one of the preceding claims, characterised in that an axial displacement of the tool drive shaft (24) in the direction of the drive (12) can be limited by a rear stop position.
27. Screwdriving machine tool according to one of Claims 11 to 26, characterised in that an engagement depth of the bosses (150, 152) of the release coupling (102, 104) can be adjusted by means of the adjusting device (118).
28. Screwdriving machine tool according to Claim 27, characterised in that a distance between the first coupling element (100) and the second coupling element (104), with the tool drive shaft (24) being in the rear stop position, can be varied by means of the adjusting device (118).
29. Screwdriving machine tool according to Claim 27 or 28, characterised in that the second coupling element (104) is adjustable in the axial direction by means of the adjusting device (118).
30. Screwdriving machine tool according to one of Claims 27 to 29, characterised in that the coupling element (104) driven by the drive is displaceable in the axial direction by means of a displacement device (118) serving as an adjusting device.
31. Screwdriving machine tool according to Claim 30, characterised in that the coupling element (104) driven by the drive (12) is supported, on its side (112) located opposite the coupling element (100) connected to the tool drive shaft (24), on the displacement device (118).
32. Screwdriving machine tool according to one of Claims 30 or 31, characterised in that the displacement device (118) comprises two setting rings (114, 116) rotatable relative to one another.
33. Screwdriving machine tool according to Claim 32, characterised in that one setting ring (114, 116) has a displacement face (198) which extends with a pitch relative to the axis of rotation (26) of the relative rotation and on which the other setting ring (116, 114) rests with a supporting face (198) [sic].
34. Screwdriving machine tool according to one of Claims 12 to 33, characterised in that the actuating element (224) is guided out of the housing (10) outside a gear-case portion (66).
35. Screwdriving machine tool according to Claim 34, characterised in that the actuating element (224) is guided out of a motor-case portion (64) of the housing (10).
36. Screwdriving machine tool according to one of Claims 34 or 35, characterised in that an intermediate member (220) is guided through a wall (62) between the gear-case portion (66) and the motor-case portion (64).
37. Screwdriving machine tool according to Claim 36, characterised in that the adjusting device (118) is mounted on the wall (62) between the gear-case portion (66) and the motor-case portion (64).
38. Screwdriving machine tool according to one of Claims 32 to 37, characterised in that the setting ring (114) supporting the coupling element (104) driven by the drive (12) is arranged fixedly in terms of rotation and the setting ring (116) located on the opposite side of this coupling element (104) is arranged rotatably.
39. Screwdriving machine tool according to one of Claims 11 to 38, characterised in that the adjusting device (118) allows a variation of the distance between the coupling elements (102, 104) by at least half the height of the bosses (150, 152).
40. Screwdriving machine tool according to Claim 39, characterised in that the adjusting device (118) allows a variation of the distance between the coupling elements (102, 104) of the order of the height of the bosses (150, 152).

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