GB2334911A - Electric hand tool clutch - Google Patents

Abstract

In an electric hand tool machine having a tool spindle (12) driven by an electric motor, a torque clutch disposed in a transmission path between electric motor and tool spindle has a manual setting element (14) for setting different torque steps. For the purpose of varying the setting element (14) from machine to machine without modifying the gear unit required for setting purposes, the setting element (14) is divided into a shift ring (23), which executes the setting function and is rotatable about the machine axis, and a design ring non-rotatably connected to said shift ring for the manual, rotary operation.

Description

2334911 1 Electric hand tool maphine

Prior art

The invention proceeds from an electric hand tool machine of the type defined in the preamble of claim 1.

In a known electric hand tool machine (DE 42 13 291 AI) designed as an impact drilling machine, the torque clutch is a safety clutch in the form of a slip clutch with cup springs,. which protects machine and operator should the tool lock during drilling. The setting element for setting different operating modes enables a gear change and a switchover from impact drilling mode to hammering or cutting mode.

So-called cordless screwdrivers are known, in which the maximum permissible torque usable for tightening a screw is adjustable by means of the setting element. The torque setting is stepped and adjustable by moving the setting element into a plurality of setting positions.

Advantages of the invention The electric hand tool machine according to the invention having the features of claim 1 has the advantage that by virtue of dividing the setting element into a shift ring for executing the gear setting fimctions and a design ring for manual operation, the appearance of the setting element may be- varied from machine to machine without having to modify the gear unit rtN'-uired 30', ' W- zetting purposes. The shift ring forms part of the gear unit is defined by the re4uirements existing there and performs all of the functions which are identical in all types of gear unit. The design ring executes all variable functions, is not defined by the 2 gear unit and may be assembled and exchanged at any time. Its appearance may be varied from machine to machine, as may the number of setting positions and their position relative to the angle of rotation of the design ring. The setting gear unit is fully flinctional without the design ring, only in said case the torque adjustrnent is stepless.

Advantageous developments and improvements of the electric hand tool machine indicated in claim 1 are possible by virtue of the measures outlined in the further claims.

According to a preferred embodiment of the invention, there is integrated in the torque clutch a locking clutch, which establishes an - in direction of rotation - keyed connection between the clutch parts of the torque clutch. The locking clutch may be engaged and disengaged by means of the setting element and the switching functions required for said purpose are executed by the shift ring.

According to an advantageous embodiment of the invention, an impact mechanism is provided for axially driving the tool spindle or a tool driven by the tool spindle. The impact mechanism may be connected and disconnected by means of the setting element the switching functions required for said purpose being executed by the shift ring.

Said constructional refinements of the electric hand tool machine have the advantage that the shift ring may execute not only the setting functions for the torque clutch but also further switching functions for switching on and off specific operating modes of the electric hand tool machine, e.g. in a combined electric hand tool machine usable as a screwing or drilling tool, the "impact drilling" and "drilling" modes, in both of which the torque clutch is inoperative and at the same time the locking clutch integrated 'm the torque clutch is engaged.

The locking clutch prevents axial forces, which would lead to an extreme loading of the gear case, from being transmitted from the clutch in drilling mode and 3 relieves the load upon the clutch spring of the torque clutch, thereby substantially prolonging the useful life of the torque clutch.

According to an advantageous embodiment of the invention, the design ring is capshaped and may be snapped onto the shift ring, there beffig defined 'm the design ring the detent positions, with which are associable setting positions of the shift ring for executing the setting and switching flinctions. Thus, the design ring may be assembled at any time without an additional tool and without additional fastening means and a subsequent exchange is possible. By defining the detent positions in a different manner, it is possible with the same setting gear unit to realize the number of steps for the torque adjustment the adjusting angle from step to step and the end position angle in a different manner.

Drawings The invention is explained in greater detail in the following description of an embodiment which is illustrated in the drawings. The drawings show:

Fig. 1 Fig. 2 Fig. 3 in a cutout manner a longitudinal section through an electric hand tool machine, a perspective view of a setting element of the hand tool machine in Fig. 1, partially cut open, a perspective representation of a design ring of the setting element in Fig. 2 in two different views, 4 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 a perspective view of a detent spring of the setting element in Fig. 2, - a perspective representation of a cover of the setting element in Fig. 2, in two different views, a perspective view of a clutch of the hand tool machine in Fig. 1, partially cut open, in a cutout manner an exploded view of the clutch in Fig. 6 with parts of the setting element in Fig. 2, a perspective view of a clutch part of the clutch in Fig. 6, partially cut open, a perspective representation of the other clutch part of the clutch in Fig. 6 in two difFerent views, a perspective view of the clutch in Fig. 6 with parts of the setting element in Fig. 2, partially cut open, a perspective representation of a locking wedge of the clutch in Fig. 10, in two different views, Fig. 12 m a cutout manner a perspective view of the hand tool machine with tool spindle, pivot bearing and switchover mimic for the drilling/impact drilling switchover, partially cut open, Fig. 13 an exploded view of the drilling/impact drilling switchover mimic in Fig. 12, Fig. 14 an exploded view of tool spindle and an impact mechanism for the impact drilling mode.

Description of the embodiment

The electric hand tool machine shown in a cutout manner in longitudinal section in Fig. 1 may be used as a drilling machine, as an impact drilling machine and as an electric screwdriver with adjustable torque. A machine housing denoted by 10 accommodates an electric motor (not shown here), which via a gear unit 11 drives a tool spindle 12 supported in a spindle bearing 3 6. The tool spindle 12 at one end carries a threaded stem 12 1, on which a chuck used to clamp drill bits, impact drill bits or various screwing tools may be screwed. Disposed in the transmission path between electric motor and tool spindle 12 is a torque clutch 13, the maximum transmissible torque of which is preselectable in steps by means of a manual setting element 14. The setting element 14 moreover has a flu-ther two setting positions for setting the "impact drilling" mode and the "drilling" mode. In said two operating modes the clutch 13 is rigidly operated, i.e. is inoperative as a torque clutch and acts as a locking clutch.

In particular, the clutch 13 comprises a clutch housing 15 (Figs. 1, 2, 6, 7, 10, 12), on which an annular first clutch part 16 (Fig. 9) is held in a nonrotatable and axially displaceable manner. The first clutch part 16 is in engagement with a second clutch part 18, which is formed on a ring gear 17 of a planetary gear step of the gear urnit 11. In said case, curved clutch cams 161 on the first clutch part 16 lie between bevelled clutch cams 181 of the second clutch part 18. The second clutch part 18 additionally carTies jaws 182, which are 6 disposed radially slightly finiher out than the clutch cams 18 1 and are substantially radially aligned with the latter. The clutch part 16 also carries jaws 162, which project from the side of the first clutch part 16 remote from the second clutch part 18 and are used to anchor the first clutch part 16 non-rotatably on the clutch housing 15. The clutch housing 15 carries an external thread 151 (Fig. 7), on which a setting nut 19 may be screwed. Supported between the setting nut 19 and the first clutch part 16 is a clutch spring 20, which holds the clutch cams 161 and 181 of the two clutch parts 16 and 18 in frictional engagement. The further the setting nut 19 is advanced towards the first clutch part 16 by turning on the 1 0 external thread 15 1, the greater the preloading of the clutch spring 20 and the greater the maximum torque transmissible via the torque clutch 13 to the tool spindle 12. Provided the set torque at the tool is not exceeded, the ring gear 17 is locked and the planet wheels 21 supported on a planet carrier 22 roll along the internal gearing 171 of the ring gear 17. The consequently rotating planet carrier 22 drives the tool spindle 12. I however, the counter-torque acting upon the tool spindle 12 exceeds the torque set by means of the clutch spring 20, the clutch cams 161 and 181 of the two clutch parts 16 and 18 rotate past one another. The ring gear 17 of the gear unit 11 is therefore no longer locked, with the result that the planet wheels 21 in the gear unit 11 are no longer supported against the internal gearing 171 of the ring gear 17 and so are no longer able to transmit torque via the planet carrier 22 to the threaded spindle 12.

As Figs. 1 and 2 reveal, the setting element 14 comprises an operating sleeve 23 (Fig. 7), a cap-shaped design ring 24 (Fig. 3) overlapping the operating sleeve 23, and a cover 25 (Fig. 5) which is snapped onto tile end face of the clutch housing 15 and used for guidance of the operating sleeve 23 and for axial, rotatable mounting of the design ring 24. The snap-action hooks for fastening the cover 25 are denoted in Figs. 5 and 2 by 251 and the snap- action hooks for receiving the design ning 24 are denoted by 252. It is evident from Fig.

7 2 that the snap-action hooks 251 engage behind corresponding lugs 152 of the clutch housing 15 and the snap-action hooks 252 engage into an annular groove 245 of the design ring 24. The operating sleeve 23 guided on the cover 25 engages with a spline profile into the setting nut 19 so that, upon rotation of the operating sleeve 23, the setting nut 19 is driven and screwed with simultaneous axial displacement on the external thread 151 of the clutch housing 15. Operating sleeve 23 and setting nut 19 together form a shift ring, by means of which all setting flinctions of the torque clutch 13 as well as all switching flinctions for engaging and disengaging the locking clutch integrated in the torque clutch 13 and for switching on and off an impact mechanism 30, yet to be described, for the "impact drilling" mode are executed. Between the cover 25 and the clutch housing a detent spring 26 (Fig. 4) is clamped so as to be locked against rotation and displacement. The detent spring 26 has a detent head 26 1, which interacts with detent recesses 241 in the design ring 24. The position and number of the detent recesses 241 in the design ring 24 determine the position and number of the individual setting positions of the setting element 14. The design ring 24 is snapped onto the operating sleeve 23 and connected non-rotatably to the latter.

To said end, webs 242 at the inside of the design ring 24 (Fig. 3B) engage into corresponding recesses 231 in the operating sleeve 23 (Fig. 7). Snapaction elements 243, which are formed at the inside of the design ring 24 and engage behind corresponding lugs 232 formed at the top of the operating sleeve 23 (Fig.

2), are used to fix the design ring 24 in an axially non-displaceable manner on the operating sleeve 23.

The order of the setting positions of the setting element 14 is defined in such a way that in the first setting position the "impact drillinJ mode, in the following second setting position the "drilling" mode and in further, e.g. fifteen, successive setting positions different torque steps of the torque clutch 13 for use of the hand tool machine as a screwdriver are adjustable. With increasing rotation 8 of the design ring 24, i.e. with an ascending number of setting position, the maximum transmissible torque set in the torque clutch 13 increases step by step. In the first two setting positions of the design ring 24, the torque clutch 13 is rendered inoperative and the locking clutch engaged, the clutch spring 20 being 5 in said case substantially unloaded.

For rendering the torque clutch 13 rigid and/or engaging the locking clutch integrated in the torque clutch 13, in the clutch housing 15 a plurality of locking wedges 27 distributed over the periphery are guided in an axially displaceable manner and overlap the clutch part 16, which is fixed non-rotatably on the clutch housing 15, between the jaws 162. In Fig. 10 only one locking wedge 27 may be seen, which is illustrated in two dilferent views in Fig. 11. As may also be seen in Fig. 10, the locking wedge 27 is pressed by means of a compression spring 28 supported in the clutch housing 15 towards an axially ascending, peripherally extending curved path 29 formed on the operating sleeve 23. Said compression spring 28 acts upon the one end face 271 (Fig. 1 1B) aligned at right angles to the direction of displacement of the locking wedge 27 and is accommodated by a pin 273, while the opposite end face 272 lies against the curved path 29. The two longitudinal faces 274 and 275 of the locking wedge 27, which extend parallel to the direction of displacement of the locking wedge 27, 20 take the form of stop faces. In the first two setting positions of the design ring 24 for the "impact drilling" and "drilling" modes, the operating sleeve 23 is in such a position of rotation that the curved path 29 pushes the locking wedge 27 counter to the compression spring 28 in between the jaws 182 of the second clutch part 18. Thus, one of the stop faces 274, 275 of the locking wedge 27 lies against one of 25 the axially extending faces 182a or 182b of the jaws 182 (Fig. g), and a purely keyed connection is established between the two clutch parts 16, 18. Given a plurality of locking wedges 27 distributed uniformly over the periphery, each locking wedge 27 is supported against a separate curved path 29, the curved paths 9 29 beffig disposed at a radial distance from, and concentric with, one another on the end face of the operating sleeve 23 directed towards the clutch 13. When the design ring 24 is further rotated past the first two setting positions, the curved paths 29 move back and the locking wedges 27 are pushed by the compression springs 28 back out of the second clutch part 18, with the result that the torque clutch 13 is then operative, its maximum transmissible torque being determined by the preloading force of the clutch spring 20.

For the "impact drilling" mode the tool spindle 12, in addition to its rotational motion, is also set in an axially reciprocating motion with a short axial stroke. To said end, a ratchet forming an impact mechanism 30 and having two ratchet parts 31, 32 (Figs. 1 and 14) is provided, the first ratchet part 31 being rigidly connected to the tool spindle 12, while the second ratchet part 32 is fixed in a non-rotatable and axially displaceable manner in the clutch housing 15. A compression spring 33 fixes said second ratchet part 32 against a stop 34 in the clutch housing 15. The two ratchet parts 31, 32 of the impact mechanism 30 shown in an exploded view in Fig. 14 are held with their opposing ratchet tooth systems in mesh by means of the compression spring 33 and a ffirther compression spring 35, which is supported between the tool spindle 12 and the spindle bearing 36. The axial stroke eflEected during rotation by the tool spindle 12 is determined by the axial height of the ratchet tooth systems. When the design ring 24 is situated in its first setting position, the two ratchet parts 3 1, 3 2 are meshed by their ratchet tooth systems. The impact mechanism 30 is switched on. When the design ring 24 is turned into its next setting position, a displacement mimic 3 7 ensures that the tool spindle 12 is displaced far enough (in Fig. 1 to the right) for the two ratchet parts 31, 32 to be disengaged, this being shown in Fig. 1. During displacement of the tool spindle 12, the second ratchet part 32 is applied under the action of the compression spring 33 against the stop 34 in the clutch housing 15 so that it is unable to follow the displacement motion of the tool spindle 12 and hence of the first ratchet part 3 1. The impact mechanism 30 is switched off. The tool spindle 12 executes a purely rotational motion.

The displacement mimic 37, which is illustrated only as a constructional unit in Fig. 1 for the sake of clarity, is shown in an exploded view in Fig. 13. It comprises a bearing pot 38, in which the spindle bearing 36 is positively received and pressed by the pressure spring 35 against the pot base, a link ring 3 9 which is seated non-rotatably on the clutch housing 15, and a coupling ring 40 which overlaps the link ring 39 at the periphery with segments 40 1, which are positively received in the operating sleeve 23 and establish a non-rotatable connection between operating sleeve 23 and coupling ring 40. The link ring 39 at its end face directed towards the coupling ring 40 carries two lifting ramps 41, which are arranged at a distance from one another in peripheral direction. Each lifting ramp 41, viewed in peripheral direction, ascends out from the annular surface of the link ring 39 and descends back towards the annular surface. The coupling ring 40, which lies flat against the annular surface of the link ring 39, carries in the region of each lifting ramp 41 a recess 42, the length of each recess 42 being greater than the ramp length- The bearing pot 38 by means of three claws 43, which are disposed offset by identical angles at circumference relative to one another, overlaps the coupling ring 40 at its end face remote from the link ring 39, the claws 43 simultaneously fixing the bearing pot 3 8 non-rotatably in the link ring 39.

A perspective view of the assembled displacement mimic 37 is shown in Fig. 12. In the position shown there, the lifting ramps 41 on the link ring 39 project through the recesses 42 in the coupling ring 40, and the coupling ring 40 lies flat against the link ring 39. After the above-said, the tool spindle 12 is displaced by the pressure spring 35 far enough, in Fig. 1, to the left for the ratchet parts 31, 32 to be in mesh with one another and for the second ratchet part 32 to have lifted off the stop 34. The "impact dfflhng" mode is switched on, the locking 11 clutch being engaged by virtue of the appropriate rotational position of the operating sleeve 23. When the design ring 24 is then turned into its second setting position, the coupling ring 40 slides onto the lifting ramps 41 and the bearing pot 38 via the claws 43 is displaced axially counter to the action of the pressure spring 35. The spindle bearing 36 supported against a shoulder 122 of the tool spindle 12 (Fig. 1) displaces the tool spindle, in Fig. 1, to the right. The axial displacement which is determined by the axial height of the lifting ramps 41, is such that the ratchet parts 31, 32 disengage and the second ratchet part 32 is applied against the stop 34. The "drilling" mode is set the locking clutch continuing to remain engaged by virtue of the appropriate rotational position of the operating sleeve 23. When the design ring 24 is turned out of said second setting position into further setting positions, the co-rotating coupling ring 40 is no longer able to leave the lifting ramps 41 so that in all further rotational positions of the design ring 24, the impact mechanism 30 is inoperative. At the same time, in said range of rotation the curved paths 29 on the operating sleeve 23 are so designed that the locking wedges 27 are pushed by their compression springs 28 back out of the second clutch part 18 so that the locking clutch is disengaged and the torque clutch 13 is operative.

The invention is not limited to the described embodiment. For instance, the order, in which the setting positions of the setting element 14 for the "impact drilling" and "drffiffig" modes and for torque selection are arranged, is not compulsory. Given a suitably different construction of the displacement mimic 37, the setting positions for the "impact drilling" and "drilling" modes may swap places. Also, said two setting positions need not necessarily come before the group of setting positions for torque selection, although this is advantageous for relieving the load upon the clutch spring 20 in said two operating modes. At the cost of a specific load upon the clutch spring, it is for example also possible for further setting positions for the "drilling" and/or "impact drilling" modes to be 12 interspersed among the group of torque setting positions. By said means, shorter switchover paths for the setting element 14 may be achieved.

11 1 13

Claims (1)

1. Claims

   1.

   2.

   Electric hand tool machine having a tool spindle (12) driven by an electric motor, a torque clutch (13) disposed in a transmission path between electric motor and tool spindle (12) for transmitting a preselectable maximum torque and having a manual setting element (14) for setting different torque steps in the torque clutch (13), characterized in that the setting element (14) comprises a shift ring (19, 23), which executes the setting fimctions and is rotatable about the machine axis, and a design ring (24) non-rotatably connected to said shift ring for the manual, rotary operation.

   Machine according to claim 1, characterized in that integrated Mi the torque clutch (13) is a locking clutch, which establishes an - in direction of rotation - keyed connection between the clutch parts (16, 18) of the torque clutch (13), that the locking clutch may be engaged and disengaged by means of the setting element (14) and that the switching functions for engaging and disengaging the locking clutch are assigned to the shift ring (19, 23).

   Machine according to claim 1 or 2, characterized in that an impact mechanism (30) for axially driving the tool spindle (12) or a tool driven by the tool spindle (12) is provided, that the impact mechanism (30) is connectable and disconnectabIe by means of the setting element (14) and that the switching fimctions for connecting and disconnecting the impact mechanism (30) are assigned to the shift ring (19, 23).

   14 4.

   5.

   lo 6.

   7.

   8.

   Machine according to one of claims 1 - 3, characterized in that the design ring (24) is cap-shaped and may be snapped onto the shift ring (19, 23).

   Machine according to one of claims 1 - 4, characterized in that the design ring (24) has detent positions, with which are associable setting positions of the shift ring (19, 23) for executing the setting and switching flinctions.

   Machine according to one of claims 1 - 5, characterized in that the detent positions of the design ring (24) are defined by detent recesses (24 1), which are disposed at the inside of the design ring (24) distributed over the latter's periphery and cooperate with a fixed detent spring (26).

   Machine according to one of claims 1 - 6, characterized in that the sliffi ring comprises an operating sleeve (23) and a setting nut (19), which are connected to one another in a non-rotatable and axially relatively displaceable manner, and that the cap-shaped design ring (24) overlaps the operating sleeve (23), preferably completely, and is snapped firmly in position on the latter.

   Machine according to claim 7, characterized in that the torque clutch (13) comprises a clutch housing (15) and two clutch parts (16, 18), which are held in frictional engagement with one another by a clutch spring (20), and that the setting nut (19) is seated screwably on the clutch housing (15) and the clutch spring (20) is supported between the setting nut (19) and the one clutch part (16) fixed in a non-rotatable and axially displaceable manner on the clutch housing (15).

   9.

   10.

   11.

   Machine according to claim 8, characterized in that latched on the clutch housing (15) is a cover (25), against which the operating sleeve (23) is guided and on which the cap-shaped design ring (24) is firmly snapped in a rotatable manner.

   Machine according to claim 9, characterized in that the detent spring (26) is clamped between clutch housing (15) and cover (25) so as to be locked against rotation and displacement and engages with a detent head (26 1) into the detent recesses (24 1) of the design ring (24).

   Machine according to one of claims 8 - 10, characterized in that the locking clutch integrated in the torque clutch (13) comprises at least one locking wedge (27), which isfixed in an axially displaceable manner in one clutch pail (16) and as a result of axial displacement projects in such a way between jaws (182) disposed on the second clutch part (18) that axially extending stop faces (274, 275, 182a, 182b) of locking wedge (27) and jaws (182) lie against one another, and that formed on the operating sleeve (23) is at least one curved path (29) ascending in axial direction and extending in peripheral direction, against which the at least one locking wedge (27) is supported under spring action by an end face (272) extending at right angles to the stop faces (274, 275).

   16 12.

   13.

   14.

   15.

   Machine according to claim 11, characterized in that a compression spring (28) is supported between the end face (271), remote from the curved path (29), of the at least one locking wedge (27) and the clutch housing (15).

   Machine according to claim 11 or 12, characterized in that the at least one curved path (29) is formed in such a manner on the operating sleeve (23) that in a preselected angle-of-rotation region of the operating sleeve (23) between two successive detent positions of the design ring (24) the at least one locking wedge (27) lies in the region of the axially highest elevation of the curved path (29) against the latter.

   Machine according to one of claims 11 - 13, characterized in that a plurality of locking wedges (27) are provided, which are distributed preferably uniformly over the periphery of the clutch parts (16, 18) of the torque clutch (13), that in each case one locking wedge (27) lies against a separate curved path (29) and that the curved paths (29) are disposed concentrically at a radial distance from one another on the end face of the operating sleeve (23) directed towards the clutch parts ( 16, 18).

   Machine according to one of claims 7 - 14, characterized in that the impact mechanism (30) comprises a first ratchet part (3 1) rigidly connected to the tool spindle (12) and a second ratchet part (32) disposed in a non-rotatable and axially displaceable manner, the ratchet tooth systems of which are in engagement with one another by virtue of spring forces acting upon the ratchet parts (31, 32), and 1 7 that the operating sleeve (23) is so designed that in one angle- ofrotation region it effects an axial displacement of the tool spindle (12) in such a manner that the two ratchet parts (31, 32) are disengaged.

   16.

   17.

   18.

   Machine according to claim 15, characterized in that a spindle bearing (36) receiving the tool spindle (12) is seated in a bearing pot (38), which is disposed so as to be non-rotatable and axially displaceable relative to the clutch housing (15) and in the angle-ofrotation region of the operating sleeve (23) executes an axial stroke which decouples the ratchet parts (31, 32), the one axially displaceable ratchet part (32) loaded by a compression spring (33) being supported against a stop (34).

   Machine according to claim 16, characterized in that the spindle bearing (36) is fixed in a flictionally engaged manner to the base of the bearing pot (38) by means of a pressure spring- (35) supported against the tool spindle (12).

   Machine according to claim 17, characterized in that seated nonrotatably on the clutch housing (15) is a link ring (39), which on its annular surface remote from the bearing pot (3 8) carries two axially projecting lifting ramps (41), which are disposed a distance apart from one another in peripheral direction and in each case in peripheral direction ascend out from the annular surface and descend back towards the annular surface, that lying against the end face of the link ring (39) is a coupling ring (40), which is nonrotatably connected to the operating sleeve (23) and in the region of 18 each lifting ramp (4 1) carries a recess (42), the length of which is greater than the ramp length, and that the coupling ring (40) at its end face remote from the link ring (39) is overlapped by at least two claws (43), which are disposed at an identical angle at circumference to one another on the bearing pot (38) and simultaneously fix the bearing pot (38) non-rotatably in the link ring (39).

   19.

   An electric hand tool machine substantially as herein described with reference to the accompanying drawings.