EP1946892A2 - Impact wrench - Google Patents

Abstract

The impact screwdriver has two drive shafts (4,5). A switching device for switching percussive operation over to the non-percussive operation by an operating device (36), operated from outside. A switching ring (35), which is adjusted between a non-operating position assigned to the percussive operation. An operating position is assigned to the non-percussive operation, which is arranged, in torque-proof and axially sliding manner, outside concentric to the drive shaft. The switching ring is supported on a switching ring support part (37) connected with the drive shaft.

Description

The invention relates to an impact wrench to non-impact mode switchable impact wrench, arranged with a motor driven drive shaft, a coaxial to the drive shaft, rotatably mounted relative to the drive shaft output shaft and a concentric to the drive shaft mounted on this, in driving connection with the drive shaft and by a spring force in Impact body acted upon in the axial direction to the output shaft, which is in rotational driving engagement with the output shaft in a forward position to the output shaft and connected by at least one cam arrangement and an engaging in this control with the drive shaft such that during impact operation of the shock body when on the Output shaft from the outside no counter-torque or a smaller counter-moment acts as a limit counter-moment, assumes its front position and, if on the output shaft from the outside, the limit Gegenmome nt, contrary to the spring force performs an axial movement to the rear with superimposed rotary motion relative to the drive shaft, rotates past the output shaft and then passes under the spring force back into its forward position and exerts a shock on the output shaft in the circumferential direction.

Impact wrenches are used for tightening screws or loosening tightened screws. For this purpose, the impact wrench is attached to the respective screw and in operated according to the tightening or loosening corresponding direction of rotation, so that in the impact mode when the limit counter-torque occurs consecutive, pulse-like blows in the circumferential direction on the output shaft and thus exerted on the screw.

These impact wrenches are usually hand tools.

One from the EP 1050381 A2 Known impact wrench can be switched from the described impact mode to a non-impact operation by the output shaft is always connected to the drive shaft, regardless of the counter-torque acting on them, so that the impact wrench works like a normal screwdriver, in which no impact function is integrated.

In the known impact wrench, a drive shaft in the axial direction enforcing switching pin is present, which is advanced to switch from the impact mode to the non-impact mode, so that it comes into rotationally fixed engagement with the output shaft and this directly rotatably connected to the drive shaft.

One of the disadvantages of this impact wrench is that the switching pin has a fairly small diameter, so that only correspondingly small torques can be transmitted from the drive shaft to the output shaft.

The present invention has for its object to provide an impact wrench of the type mentioned, with a simple and stable structure and easy to handle manner of impact operation on the non-impact operation can be switched and allowed in non-impact operation, the transmission of relatively large torques.

This object is achieved in that the switching means for switching from impact mode to the non-impact operation operable by an actuator from the outside, between an impact mode associated inoperative position and the non-impact operation associated effective position adjustable shift ring containing radially outwardly of the drive shaft concentric arranged for this and rotatably mounted on a non-rotatably connected to the drive shaft switching ring bearing part and axially displaceable and when moving from its the impactor uninfluenced letting inactive position reaches its operative position in rotationally fixed locking engagement with the striker.

In this way, the impactor is locked in non-impact mode on the switching ring with the drive shaft, so that the impactor no longer rotate relative to the drive shaft and thus can not shift axially. Therefore, the impactor can no longer dodge as it were and get out of engagement with the output shaft when acting on the output shaft of the limiting counter-torque. Therefore, the output shaft is always connected rotationally fixed to the drive shaft.

The switching ring may have a relatively large diameter, so that correspondingly large torques can be transmitted.

Advantageous embodiments of the invention are specified in the subclaims.

Figur 1

einen erfindungsgemäßen Schlagschrauber in Außenansicht in Schrägansicht,

Figur 2

den Schlagschrauber nach Figur 1 in Teildarstellung in Seitenansicht, wobei das Gehäuse des Schlagschraubers im vorliegend interessierenden Bereich entfernt ist und der Schlagschrauber sich im Betriebszustand "Schlagbetrieb" befindet,

Figur 3

die Anordnung nach Figur 2 im Betriebszustand "Nichtschlagbetrieb",

Figur 4

die Anordnung nach Figur 2 im zur Zeichenebene der Figur 2 parallelen Schnitt,

Figur 5

die Anordnung nach Figur 4 in Draufsicht gemäß Pfeil V, teilweise im Schnitt,

Figur 6

die Anordnung nach Figur 2 in Stirnansicht gemäß Pfeil VI und

Figur 7

den vorderen Bereich der Antriebswelle in gesondertem Zustand in Seitenansicht mit schematisch angedeuteter Steuerkurvenanordnung mit zugeordnetem Steuerelement.

An embodiment of the invention will be explained in detail below with reference to the drawings. Show it:

FIG. 1

an impact wrench according to the invention in an external view in an oblique view,

FIG. 2

after the impact wrench FIG. 1 in a partial view in side view, wherein the housing of the impact wrench in the present area of interest is removed and the impact wrench is in the operating state "impact mode",

FIG. 3

the arrangement after FIG. 2 in the operating state "non-impact operation",

FIG. 4

the arrangement after FIG. 2 im to the drawing level of FIG. 2 parallel cut,

FIG. 5

the arrangement after FIG. 4 in plan view according to arrow V, partly in section,

FIG. 6

the arrangement after FIG. 2 in front view according to arrow VI and

FIG. 7

the front portion of the drive shaft in a separate state in side view with schematically indicated cam arrangement with associated control.

From the drawing is a trained as a hand-held impact wrench 1 with an electric drive motor 2, a driven by the drive motor 2 gear unit 3, a driven by the gear unit 3 drive shaft 4 and a coaxial with the drive shaft 4 arranged output shaft 5, which are in an elongated device housing 6, which may be formed in several parts, are added. From the device housing 6 is a handle 7 forming housing part 8 pistol-like.

The impact wrench 1 is designed as a cordless device. For this purpose, a receptacle for a battery pack is arranged at the bottom of the handle 7. Instead of using a rechargeable battery, however, the impact wrench could also be operated with mains power.

At the top of the handle 7, a user-actuated push-button 10 is arranged at the front, via which a lying in the power supply operating switch 11 is actuated.

The output shaft 5 is at the front of the device housing 6 in front of this and can be connected to a turning tool for screwing or unscrewing a screw. The protruding output shaft portion 12 is formed as a square shaft 13 and includes an outgoing from its front polygonal recess 14. On the square shaft 13, a conventional socket wrench can be inserted non-rotatably having a polygonal receptacle for rotationally fixed insertion of a polygonal screw head. Instead of a socket wrench can also be attached to the square shank a header, on which in turn a turning tool can be set. The polygonal recess 14, however, can be used for the rotationally fixed insertion of a bit-like turning tool.

The impact wrench 1 is switchable from a beating operation to a non-impact operation. In non-impact operation ( FIG. 3 ), the output shaft 5 is independent of the applied torque or regardless of the incoming or ausudrehenden from the screw acting on the output shaft counter torque non-rotatably connected without interruption to the drive shaft, so that the impact wrench 1 works like a conventional screwdriver without impact function.

In the impact mode, however, successive, pulse-like impacts in the circumferential direction are exerted on the output shaft when exceeding a force exerted externally on the output shaft 5 limit Gegenmoments, so tighten in comparison to the non-impact operation a screw and a stuck screw can be solved easily.

It is understood that the output shaft 5 can be selectively driven in both directions of rotation.

For the impact operation a suitably trained impact mechanism is available.

The output shaft 5 is rotatably supported relative to the drive shaft 4. In the embodiment, the drive shaft 4 on its output shaft 5 side facing a bearing extension 16 which engages in a bearing recess 15 of the output shaft 5 rotatably. The output shaft 5 is rotatably supported in the device housing 6 by means of a pivot bearing 17 arranged on its outer circumference.

The output shaft 5 also has at least one, advantageously a plurality of, in particular two diametrically opposed, radially outwardly projecting output drive projections 18, 19 (see in particular the FIGS. 2, 3 and 6 ), so that in the circumferential direction between the output driving projections 18, 19 spaces 20, 21 are formed.

On the drive shaft 4, a concentric with the drive shaft 4 arranged impactor 22 is mounted, which is in a manner to be described in driving connection with the drive shaft 4, but it can perform on the drive shaft 4 an axial movement with superimposed rotary motion. The impactor 22 is acted upon by a spring force applied by a coil spring 23 in the direction of the output shaft 5 and takes except in the impact mode when acting on a counter-torque exceeding the counter-torque under the spring force to the output shaft 5 toward a forward forward position, which in the Drawing is shown. In this front position, the striker 22 is in rotational engagement with the output shaft 5. For this purpose, the striker 22 at its output shaft 5 facing end in the number of output driving projections 18, 19 of the output shaft 5 corresponding drive driving projections 24, 25, the protrude in the axial direction of the impactor body 22 and engage in the front position of the impactor body 22 in each case in one of the intermediate spaces 20, 21 between the output drive projections 18, 19.

The driving entrainment projections 24, 25 have a smaller circumferential extent than the intermediate spaces 20, 21 between the driven entrainment projections 18, 19, so that the impactor body 22 and the output shaft 5 are relatively rotatable relative to one another. If the striking body is in its forward position, the driving entrainment projections 24, 25 lie in the direction of rotation of the drive shaft 4 on the driven entrainment projections 18, 19, so that the output shaft 5 is taken in the direction of rotation.

The impactor body 22 and the drive shaft 4 are connected to each other via two diametrically opposite cam assemblies 26, 27, each with associated and in the respective control cam assembly 26, 27 engaging control 28, 29 in the form of a control ball 30, 31. In principle, one of the two cam arrangements would suffice.

In the exemplary embodiment, each control cam arrangement 26, 27 has a V-shaped extending control groove 32 on the outer circumference of the drive shaft 4, in which the respective control ball 30, 31 engages. The tip of the V-shape of the cam groove 32 faces the output shaft 5. The respective control ball 30, 31 protrudes from the relevant control groove 32 of the drive shaft 4 and abuts a respective control surface 33 on the inner periphery of the impactor 22. In FIG. 7 is the control surface 33 indicated by dash-dotted lines. The control surface 33 is formed on the inner circumference of the impactor body 22 at the transition to an extension 34, facing the output shaft 5, of the inner cross-section of the impactor body 22. The control surface 33 also has a V-shaped profile, wherein the tip of the V, however, faces away from the output shaft 5. Instead of the control surface 33, however, a control groove corresponding course could be provided on the inner periphery of the impactor 22. In the initial rotational position, that is, when the striking body 22 assumes its front position, the respective control ball 30, 31, as is out FIG. 7 at the top of the V-shaped cam groove 32 and the tip of the V-shaped cam 33.

With the help of these at least one cam arrangement 26, 27 and associated control ball 30, 31, the striking body 22 during impact operation when the output shaft 5 from the outside a larger counter-torque than the limit counter-torque is applied, against the spring force axial movement to the rear with superimposed Rotary movement relative to the drive shaft 4, so that the striking body 22 rotates past the output shaft 5 and then again under the spring force forward to the front position and thereby with its drive-driving projections 24, 25 in the spaces 20, 21 against the output driving projections 18, 19 of the output shaft 5 is moved, so that in the circumferential direction a blow to the output driving projections 18, 19 and thus exerted on the output shaft 5.

To switch from this impact mode to the non-impact operation, a switching ring 35 is present, which can be actuated by means of an actuating device 36 from the outside and between an impact position associated with the inoperative position and the non-impact mode associated effective position. The switching ring 35 is arranged radially outside of the drive shaft 4 concentric with this. In this case, the switching ring 35 is rotatably mounted on a rotatably connected to the drive shaft 4 switching ring bearing part 37 and axially displaceable. In its inoperative position ( Figures 2 . 4 and 5 ) is the switching ring 35 away from the impactor 22, so that the impactor 22 is unaffected by the switching ring 35. Moves you the switching ring 35, however, in its operative position to the impactor 22 back, the switching ring 35 comes into rotationally fixed locking engagement with the impactor 22. For this purpose, the switching ring 35 a plurality of distributed over the circumference, the impactor 22 projecting toward locking projections 38 on (in principle, only such a locking projection 38 could be present). Each locking projection 38 is assigned a arranged at the facing end of the impactor 22 locking recess 39. When transferring the switching ring 35 in its operative position, the locking projections 38 engage in the locking recesses 39, so that the striking body 22 is rotatably connected to the switching ring 35. Conversely, the arrangement could also be made so that the locking projections on the striker and the locking recesses are arranged on the switching ring.

Since the switching ring 35 on the other hand rotatably connected to the switching ring bearing part 37, which in turn is in a rotationally fixed connection with the drive shaft 4, results in the operative position of the switching ring 35, a rotationally fixed connection of the impactor 22 with the drive shaft 4. At the same time can Impactor 22 also no longer move in the axial direction, so that the impactor 22 is independent of the externally applied to the output shaft 5 counter-torque in rotational engagement with the output shaft 5.

Another advantage of the impact wrench 1 is that the impactor body 22 in the inoperative position of the switching ring 35 automatically off such a rotational position relative to the switching ring 35 assumes that the locking recesses 39 of the impactor 22 in the axial direction in alignment with the locking projections 38 of the switching ring 35 are arranged so that the switching ring 35 immediately enters his locking into the operative position with its locking projections 38 in the locking recesses 39 of the impactor body 22 and no further manipulations are required to bring the locking projections 38 and the locking recesses 39 in an aligned position. This results as a result of the spring force acting on the impact body 22 and the at least one control cam arrangement 26, 27 with associated control ball 30, 31.

Furthermore, it is expediently provided that the end face regions 40, 41 of the striking body 22 arranged between two respective locking recesses 39 have a course which is recessed with respect to the mouths of the locking recesses 39, so that the aforementioned end face regions 40, 41 form depressions on the end face of the striking body 22. In this way it is avoided that the latching projections 38 of the switching ring 35 can collide with the end face of the impactor 22 in impact mode.

The transmission unit 3 includes a drive shaft 4 driving planetary gear. On the output side, this planetary gearset includes a set of planetary gears 42 distributed over the circumference, which radially inwardly mesh with a sun gear 43 driven by the drive motor 2 and radially outwardly with a ring gear 44 enclosing the set of planetary gears 42. The planetary gears 42 are each rotatably mounted on a Planetenradwelle 45 which project from an annular peripheral web body 46 which is arranged on the impactor 22 side facing the planetary gear 42. The drive shaft 4 is rotatably and axially fixedly connected to the web body 46, so that the drive shaft 4 is driven via the planetary gear.

In the embodiment, it is a multi-stage, switchable planetary gear. However, in the present case, it is only essential that the planetary gear mechanism has a web body facing the striking body 22, that is, the web body 46. This web body 46 is designed such that it also forms the switching ring bearing part 37. Here, the switching ring 35 is rotatably mounted on the outer circumference of the web body 46 and axially displaceable. In this way, no separate switching ring bearing part is required, so that results in a low-part arrangement.

The web body 46 has a smaller diameter than the impactor 22, so that the web body 46, as shown in FIGS. 4 and 5 it can be seen, a piece immersed in the impactor 22.

For rotationally fixed, but axially displaceable mounting of the switching ring 35 on the web body 46 groove-like, axially directed guideways 47 are arranged on the outer periphery of the web body 46. The arrangement is suitably made so that the locking projections 38 of the switching ring 35 run radially inward in the guideways 47 and engage in the non-impact operation with its radially outer region in the locking recesses 39 of the impactor body 22.

The striker 22 acting on the front coil spring 23 is supported with its rear end on the web body 46, which is arranged fixed in the axial direction. The coil spring 23 rotates during operation of the impact wrench 1 with.

The impactor 22 has an open towards the rear, annular circumferential recess 48 into which engages the coil spring 23 and is mounted with the respective end. The web body 46 also forms an annular circumferential recess 49, which is open towards the front and receives the rear end of the coil spring 23. This contributes to the space-saving design. In principle, only one of the two recesses 48, 49, expediently the recess 48 in the impactor 22, could be present.

The actuating device 36, with which the switching ring 35 can be displaced, has an externally on the device housing 6 movably arranged actuating element 50, from the movement of the axial displacement movement of the switching ring 35 is derived. For this purpose, the switching ring 35 on its outer circumference on a circumferential annular groove 51 into which a suitably U-like switching bracket 52 engages, which preferably consists of wire material. The switch bracket 52 is movable in the axial direction and is actuated by means of the actuating element 50.

During operation of the impact wrench 1, the switching bracket 52 remains in the direction of rotation, and the switching ring 35 rotates past the switching bracket 52.

The actuating element 50 is formed in the expedient embodiment of an annular, rotatably mounted on the housing 6 rotary valve 53 which is connected to the switch bracket 52 so that its rotational movement is converted into the axial displacement movement of the switching ring 35. This movement conversion takes place by means of a flat shape having deflecting part 54, on the one hand carries the switching bracket 52 and on the other hand with the rotary valve 53 in engagement is that the switching bracket 52 and with this the switching ring 35 moves in the axial direction when the rotary valve 53 is rotated.

Claims (12)

From striking operation to non-impact operation switchable impact wrench, with a motor driven drive shaft (4), a coaxial with the drive shaft (4) arranged relative to the drive shaft (4) rotatably mounted output shaft (5) and concentric with the drive shaft (4) mounted on this, in driving connection with the drive shaft (4) standing and by a spring force in the axial direction to the output shaft (5) acted upon impactor (22) in a forward to the output shaft (5) pushed forward position in rotational engagement with the output shaft (5) and by at least one control cam arrangement (26, 27) and an engaging in this control element (28, 29) with the drive shaft (4) is connected such that during impact operation of the striking body (22), if on the output shaft (5) from the outside no Counter moment or a smaller counter moment acts as a limit counter moment, assumes its front position and, if on the Abtri ebswelle (5) from the outside, the limit counter-torque acts, contrary to the spring force an axial movement to the rear with superimposed rotary motion relative to the drive shaft (4) rotates past the output shaft (5) and then passes under the spring force back to its forward position and exerts on the output shaft (5) a shock in the circumferential direction, characterized in that the switching means for switching from the impact operation to the non-impact operation by means of an actuator (36) operable from the outside, between an impact position associated with the inoperative position and the non-impact operation effective position adjustable shift ring (35) contains, which is arranged radially outside of the drive shaft (4) concentric to this and on a rotatably connected to the drive shaft (4) switching ring bearing part (37) rotatably and axially displaceably mounted and when moving from his the impactor (22) uninfluenced letting ineffective Position in its operative position in rotationally fixed locking engagement with the striker (22) passes. Impact wrench according to claim 1, characterized in that the locking engagement by means of at least one locking projection (38) on the switching ring (35) or on the striking body (22) and at least one locking recess (39) on the striking body (22) or on the switching ring (35), wherein the impactor (22) in the inoperative position of the switching ring (35) with the impact wrench automatically such a rotational position relative to the switching ring (35) assumes, in which the at least one locking recess (39) or the at least one locking projection on the striker (22) in the axial Direction in alignment with the at least one locking projection (38) or at least one locking recess (39) on the switching ring (35) is arranged. Impact wrench according to claim 2, characterized in that the at least one control cam arrangement (26, 27) has a V-like shape and the control element (28, 29) by a control ball (30, 31) is formed, so that in the output rotational position, the Control ball (30, 31) is arranged at the top of the respective V. Impact wrench according to claim 2 or 3, characterized in that the impactor (22) on its the switching ring (35) facing the end more over the circumference distributed locking recesses (39) and arranged between each two locking recesses (39) end face regions (40, 41) of the striking body (22) with respect to the mouths of the locking recesses (39) recessed course. Impact wrench according to one of claims 1 to 4, characterized in that the drive shaft (4) is driven by a planetary gear having a the impactor (22) facing, rotationally fixed and axially fixed to the drive shaft (4) connected to the web body (46), formed as the switching ring (35) rotatably on its outer circumference and axially displaceable overlapping ring gear bearing part (37) is formed. Impact wrench according to one of claims 1 to 5, characterized in that on the impactor (22) acting spring force of a coil spring (23) is applied. Impact wrench according to claim 6, characterized in that the coil spring (23) on the web body (46) is supported. Impact wrench according to claim 7, characterized in that the striker (22) and / or the web body (46) on its the web body (46) or the striker (22) facing end face an annular circumferential recess (48 or 49) for supporting the coil spring (23). Impact wrench according to one of claims 5 to 8, characterized in that the web body (46) has a smaller Has diameter as the impactor (22) and a little way into the striking body (22) dips. Impact wrench according to one of claims 1 to 9, characterized in that the actuating device (36) has an externally on the housing (6) of the impact wrench movably arranged actuating element (50), from the movement of the axial displacement movement of the switching ring (35) is derived. Impact wrench according to claim 10, characterized in that the switching ring (35) has on its outer circumference a circumferential annular groove (51) into which an axially movable, by means of the actuating element (50) operable switch bracket (52) engages. Impact wrench according to claim 11, characterized in that the actuating element (50) by an annular, rotatably mounted on the housing (6) of the impact wrench rotary slide (53) is formed, which is connected to the switch bracket (52) so that its rotational movement in the axial displacement movement of the switching ring (35) is implemented.

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