EP1941973B1 - Screwing device - Google Patents

Description

The invention relates to a screwdriver for screwing screws into workpieces according to the preamble of claim 1.

Such a screwdriver is for example off US 2004/0040727 A1 or FR 1 142 933 A1 known. To drive the output shaft in each case a lining for receiving a screwing tool is provided in these screwdrivers.

Out US 6, 655, 473 B1 is a screwdriver with a bevel gear or bevel gear known, which serves to drive a planetary gear. The screwdriver has a tool holder.

For example, for example DE 20 20006 006 273 U1 Known screwing the drive of the output shaft and thus the rotary tool via a jaw clutch. In this case, the dog clutch is disengaged in the initial state of the screwdriver due to the force acting on the output shaft spring force, so that the output shaft and with it the rotary tool occupy their front, inactive position in which the drive of the output shaft is interrupted. To screw the screwdriver is then pressed over the screw against the workpiece, so that the output shaft against the spring force moves back to its rear, active position in which the dog clutch is engaged, so that the output shaft is driven and the screw is thus screwed. Once the depth of engagement defined by the depth stop has been reached, the screwdriver is supported by the depth stop on the workpiece, so that the Output shaft is relieved and the dog clutch can disengage again.

Such screwdrivers with a depth stop are mainly used for Serienverschrauben when a plurality of screws to be screwed in succession in a workpiece. They are commonly referred to as drywall screwdrivers.

In the known devices belonging to the dog clutch parts can be subject to wear. Further, the drive motor remains in operation by turning on the screwdriver by the user until it is turned off by the user. The user regularly turns off the screwdriver only after screwing in the last screw. This ongoing running of the engine not only promotes wear, but causes a correspondingly long-lasting noise and brings a correspondingly large energy consumption with it.

The present invention is therefore an object of the invention to provide a screwdriver, which is easy to handle, is little susceptible to wear and causes as little noise. In addition, the energy consumption is to be lowered.

This object is achieved by a screwdriver according to the technical teaching of claim 1.

In this way, eliminates the existing in the prior art jaw clutch. The output shaft can remain permanently mechanically connected to the drive.

The drive motor is energized only when the screwing starts, so overcome by the pressure on the output shaft, the spring force and therefore the motion-tight connected to the output shaft operating part pushed backwards and thus the switching device is automatically transferred to its on state. At the end of the screwing operation, the actuating part moves away from the switching device, so that the drive motor is switched off automatically. In this way, the drive motor runs only during the respective screwing, so no unnecessary engine run times occur. The switching device is expediently a non-contact switching device, expediently a Hall sensor, which is associated with a permanent magnet on the actuating part.

Another measure is that the output shaft is driven by a gear transmission from the side, wherein the gear transmission includes a driven wheel seated on the output shaft and the output shaft, the driven gear in the axial direction between its front, inactive position and its rear, active position movable be upheld. In this way, the rear end of the output shaft is exposed so that they or the associated actuating part can actuate the switching device.

It is further contemplated that the output shaft and the output gear abut each other via an inclined surface arrangement, so that the movement of the output shaft in the axial direction is superimposed a rotational movement of the output shaft relative to the driven gear and the operation of the output gear to the output shaft in addition to the output shaft driving torque in axial direction forward axial force is applied.

During screwing the force exerted by the workpiece on the screw on the output shaft force presses the output shaft not only against the spring force, but also against the axial force exerted by the output gear to the rear. At the end of screwing in, when the pressure decreases to the rear, the output shaft is not only moved by the spring force, but above all by the output gear to the front. As a result, the screw is still briefly screwed into the workpiece until the actuating part has reached its switching distance to the switching device.

In principle could be dispensed with the propulsion of the output shaft through the output gear. However, the force acting on the output shaft spring force would then have to be correspondingly large. On the other hand, if the output gear exerts the said axial force on the output shaft, a relatively weak spring can be used.

Further expedient embodiments of the invention are specified in the subclaims.

Figur 1

ein erfindungsgemäßes Schraubgerät in schematischer Seitenansicht,

Figur 2

das Schraubgerät nach Figur 1 in Draufsicht gemäß Pfeil II in Figur 1,

Figur 3

den Gerätekopf des Schraubgerätes nach den Figuren 1 und 2 im Längsschnitt, wobei sich die Abtriebswelle in ihrer vorderen, inaktiven Stellung befindet,

Figur 4

die Anordnung nach Figur 3, wobei sich die Abtriebswelle in ihrer hinteren, aktiven Stellung befindet,

Figur 5

ein stark schematisiertes Blockschaltbild,

Figur 6

das Abtriebsrad des Schraubgerätes nach den Figuren 1 bis 4 im den Figuren 3 und 4 entsprechenden Schnitt in Einzeldarstellung,

Figur 7

das Abtriebsrad im gleichen Schnitt wie in Figur 6 zusammen mit der das Abtriebsrad durchgreifenden Abtriebswelle, wobei die Abtriebswelle ungeschnitten in Seitenansicht gezeigt ist, und

Figur 8

das Abtriebsrad, das der Einfachheit halber ohne seine Verzahnung gezeichnet ist, in gesonderter Darstellung in Schrägansicht gemäß Pfeil VIII in Figur 6.

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

FIG. 1

a screwdriver according to the invention in a schematic side view,

FIG. 2

after the screwdriver FIG. 1 in plan view according to arrow II in FIG. 1 .

FIG. 3

the head of the screwdriver after the Figures 1 and 2 in longitudinal section, wherein the output shaft is in its front, inactive position,

FIG. 4

the arrangement after FIG. 3 with the output shaft in its rear, active position,

FIG. 5

a highly schematic block diagram,

FIG. 6

the output gear of the screwdriver after the FIGS. 1 to 4 im the Figures 3 and 4 corresponding section in individual representation,

FIG. 7

the output gear in the same section as in FIG. 6 together with the driven gear through the output shaft, wherein the output shaft is shown uncut in side view, and

FIG. 8

the output gear, which is drawn for simplicity without its teeth, in a separate representation in an oblique view according to arrow VIII in FIG. 6 ,

The resulting from the drawing screwdriver 1 is used for screwing screws into workpieces. It is designed as a hand-held device and has a base section 2, which forms a pistol-like handle 3, on the front side of which a user to be actuated by pressing the actuator 4 of an electrical main switch is arranged. Above the handle 3, an upper portion 5 of the base portion 2 extends forward to a device head 6, which in the Figures 3 and 4 is shown separately. At the bottom of the device head 6, an electric drive motor 7 (only in FIG. 5 schematically indicated) containing motor region 8 of the base section 2 at.

In the illustrated case, the screwdriver 1 is a cordless device. The battery pack supplying power to the drive motor 7 is accommodated in a battery housing 9 detachably fastened to the base section 2 at the bottom. The power supply could be done by connecting the device by means of an electrical supply cable to the mains power instead of batteries.

The switching on and off of the drive motor 7 is controlled by the screwing, that is, the drive motor 7 is automatically set at the beginning of the screwing in motion and turned off automatically after screwing the respective screw. This is achieved in the manner described below.

The device head 6 includes a drivable by the drive motor 7 forth output shaft 10 to which a tool carrier 11 is connected, which extends coaxially to the output shaft 10 to the front 12 of the screwdriver 1 out and there has a frontal tool holder for a rotary tool 13, which is interchangeable in the tool holder inserted screwdriver bit is formed. The rotary tool 13 has a polygonal shaft 14 which is inserted into the correspondingly multi-edged tool holder of the tool carrier 11.

The tool carrier 11 extends in the axial extension of the output shaft 10 and is detachably connected to the output shaft 10 so that it can be replaced if necessary. In the connected state, the tool carrier 11 is seated firmly on the output shaft 10 both in the axial direction and in the circumferential direction.

In principle, one could also omit the separate tool carrier 11 if the output shaft 10 is extended up to the device front side 12 and provides on its front side with the tool holder accommodating the rotary tool 13.

The output shaft 10 is rotatable both at two axially spaced rotary and sliding bearings 15, 16 and in the axial direction between a front, inactive position ( FIG. 3 ) and a rear, active position ( FIG. 4 ) movably mounted. The axial movement is limited by fixedly arranged end stops, which are formed in the illustrated embodiment of the rotary and sliding bearings 16 and of a next to the other rotary and sliding bearings 15 arranged bearing ring 19. Each end stop 17, 18 is associated with a radial shoulder on the output shaft 10. It is understood that the end stops can be formed in other ways than shown.

The output shaft 10 is urged by a spring force in the direction of its front position. This spring force can be fixed by a one in the device head 6 and the other end on the output shaft 10 supporting coil spring 20 are applied.

The output shaft 10 is driven via a gear transmission from the side. The gear transmission includes a seated on the output shaft 10 output gear 21, wherein the output shaft 10, the output gear 21 passes through and thereby between its front, inactive position and its rear, active position is movable. The output gear 21 is arranged axially fixed. It is arranged between the front rotating and sliding bearing 16 and the bearing ring 19. The gear transmission is a bevel gear. The drive is effected by means of a drive shaft 22 with pinion 23, which extends transversely to the output shaft 10 and is driven by the drive motor 7 ago. The drive shaft 22 carries a first bevel gear 24 which meshes with the output gear 21 forming the second bevel gear of the gear transmission.

The output shaft 10 and the output gear 21 abut each other via an inclined surface arrangement 27, so that when the output shaft 10 is moved in the axial direction of this axial movement, a rotational movement of the output shaft 10 is superimposed relative to the output gear 21. The inclined surface arrangement 27 is in the illustrated embodiment of several - in principle would suffice - distributed over the circumference, spirally inclined to the axial direction extending inclined surfaces 25 on the inner circumference of the driven gear 21 and of the inclined surfaces 25 of the driven gear 21 associated, corresponding spirally inclined inclined surfaces 26th formed on the outer circumference of the output shaft 10.

It is understood that the inclined surface arrangement 27 can also be realized differently. So you could, for example provide on the output shaft at least one projecting guide pin in the radial direction, which engages in a spirally inclined guide groove on the inner circumference of the driven wheel and is guided in this.

In this way, in operation, when the output gear 21 rotates, exerted from the output gear 21 to the output shaft 10 in addition to the output shaft 10 driving torque an axially directed axial force. In this case, the sense of direction of the inclination of the inclined surface arrangement 27 is such that the axial force is directed forwards towards the device front side 12.

The screwdriver 1 further has on its front side 12 a depth stop 28 which limits the screwing depth when screwing in a screw and abuts the workpiece when reaching the desired screwing depth. In the exemplary embodiment, the depth stop 28 is formed by a stop sleeve 29 which surrounds the rotary tool 13 and which comes with its end face for abutment against the workpiece. The depth stop 28 is adjustable in the usual way in the axial direction. For this purpose, it can be seated in the usual way on an adjusting sleeve 30, which can be screwed back and forth in the axial direction (threaded connection 31) on a fixed housing part 32 of the device head 6.

The depth stop could also be designed differently than illustrated and be formed, for example, by a screw magazine containing a plurality of screws, which are successively conveyed to the turning tool 13. Such screw magazines are known, so that a more detailed description is unnecessary.

The output shaft 10 is, as described, movable in the axial direction between its front, inactive position and its rear, active position. This movement is used to turn on and off the drive motor 7. For this purpose, the screwdriver 1 has a switching device 33 for switching on and off the energization of the drive motor 7, wherein the switching device 33 by a movement of the output shaft 10 mitmachende actuating section 34 is switchable. The switching device 33 is in the front position of the output shaft 10 in its the energizing of the drive motor 7 preventing the off state and in the rear position of the output shaft 10 in its the energizing of the drive motor 7 permitting ON state.

In the expedient embodiment, the switching device 33 of the output shaft 10 is upstream in the axial direction to the rear. She is fixed. The actuating part 34 is arranged on the rear end face 35 of the freely ending output shaft 10 or, depending on the type of switching device 33, formed by the end face 35 itself.

The switching device 33 expediently operates without contact. It can therefore be a proximity sensor in the form of a Hall sensor. Other possibilities would be, for example, a reed sensor, an optical sensor or a magnetostrictive sensor. Depending on the type of sensor, the associated actuating part 34 is formed by a permanent magnet 36.

In a modification of the illustrated embodiment, the switching device 33 could in principle also be formed by a contact switch.

The working method is as follows:

FIG. 3 shows the starting position. The output shaft 10 is located by the force of the coil spring 20 in its front, inactive position, in which the actuating portion 34 is arranged at a distance from the switching device 33, so that an energization of the drive motor is prevented. In this off state of the drive shaft 10 is applied to the screwdriver tool 13 to be screwed on and sets the screw on the workpiece or you bring the screwdriver tool 13 into engagement with the screw head of the previously positioned on the workpiece screw. The screw, not shown, extends in the illustration according to the Figures 3 and 4 in the axial direction of the output shaft 10. The workpiece, also not shown, is found in the Figures 3 and 4 right in front of the device in the axial direction of the output shaft 10 rectangular position.

Then you press the held by the operator on the handle 3 screwdriver 1 forward. The workpiece via the screw, the rotary tool 13 and the tool holder 11 exerts a rearwardly directed counterforce on the output shaft 10, so that the output shaft 10 moves with slight rotation in the driven gear 21 against the spring force to the rear, thereby approaching the switching device 33 so that the switching device 33 is switched to its on state and the energizing of the drive motor 7 is allowed. The output shaft 10 then rotates, so that the rotationally fixed to the output shaft 10 screwdriver tool 13 is driven and screwed the respective screw. This corresponds to the FIG. 4 resulting situation.

At the end of screwing the depth stop 28 comes to rest against the workpiece. This reduces the From the workpiece via the screw on the output shaft 10 pressure exerted so that the output shaft 10 is relieved from the workpiece. The axial force exerted by the helical spring 20 and, in particular, by the drive wheel 21 on the output shaft 10 then shifts the output shaft 10 forward while simultaneously rotating the output shaft 10 (inclined surface arrangement 27) so that the actuating portion 34 moves away from the switching device 33. The screw is screwed a short distance into the workpiece, so that the screw head is sunk. If the actuating part 34 has reached the response distance to the switching device 33, the switching device 33 reaches its switch-off state, so that the drive motor 7 is no longer energized. It then comes out again FIG. 3 resulting situation.

The wiring of the switching device 33 and the required for switching on and off the energization of the drive motor 7 circuit is conventional and can be performed by a person skilled in the art without further notice.

The screwdriver 1 may conveniently be operated either in one of two modes:

The first operating mode is the single mode (standard operation). In this mode, the operator operates on the actuator 4, the main switch so that the screwdriver is turned on so far. The screwdriver is, so to speak, in a ready state. The energization of the drive motor 7 then depends on the axial position of the output shaft 10, that is, whether you press the screwdriver against the screw and the workpiece or screwing is completed.

This readiness state of the screwdriver lasts as long as the user actuates the main switch.

In the operating mode "continuous operation", however, the screwdriver is constantly in the standby position, that is, regardless of whether the user keeps the operating element 4 of the main switch inside or not. This mode can be achieved in principle by a statement of the main switch in the depressed state or by an appropriate control.

To set the respectively desired mode is the screwdriver 1, a preselection switch 37, in the case shown a rotary switch, available. In the pre-selection position "single operation", the operator must operate the actuator 4 of the main switch. If the preselection switch 37 is adjusted to the "continuous operation" position, the continuous electrical standby state is obtained via an associated control device 38.

The block diagram according to FIG. 5 shows the electrical or electronic control device 38, via which the compared to the control device 38 undersized drive motor 7 can be energized by the voltage source 39 forth. Both the actuated by the actuator 4 main switch 40 and the symbolically drawn switching device 33 are connected to the control device 38 as well as the selector switch 37. In the operating mode "continuous operation", the main switch 40 is bridged, as it were, so that the state of the switching device 33 is decisive for the energization of the drive motor 7.

On the outside of the screwdriver 1, a further switch for changing the direction of rotation of the output shaft 10 may also be provided.

The following is the appropriate action to be added:

The tool carrier 11 is fixedly connected to the output shaft 10 both in the axial direction and in the direction of rotation. This is a detachable connection, so that the tool holder 11 can be replaced if necessary. For this purpose, the output shaft 10 has a plug-in recess 42 projecting from its front end face 41 with a polygonal cross-section over at least part of its length. The tool carrier 11 forms a plug-in shaft 43 with a corresponding polygonal cross-section, so that the inserted into the plug-in recess 42 insertion shaft 43 is rotatably connected to the output shaft 10. At the insertion shaft 43, a circumferential locking groove 44 is further formed, which are associated with one or more distributed over the circumference locking body in the form of locking balls 45. The locking balls 45 are arranged in the plug-in recess 42 containing region of the output shaft 10 and each mounted in a radial direction from the outer periphery of the output shaft 10 to the plug recess 42 through radial recess 46 movable in the radial direction. The detent balls 45 is associated with a displaceable on the outer circumference of the output shaft 10 in the axial direction locking sleeve 47, which holds the locking balls 45 inwardly into the locking groove 44 in its illustrated locking position. The already described coil spring 20 is supported on the locking sleeve 47 and acts on the locking sleeve 47 and the locking balls 45, the output shaft 10 forward. The locking sleeve 47 has a front and radially outwardly rising contact surface 48, via which the locking sleeve 47 on the locking balls 45th is applied so that they are pressed inward and the tool carrier 11 is locked to the output shaft 10. To remove the tool carrier 11, you have to pull the tool holder 11 only forward. The rear flank of the locking groove 44 then pushes the locking balls 45 outwards, which moves the locking sleeve 47 against the spring force via the inclined contact surface 48, so that the tool carrier is released.

When inserting the tool carrier this displaces the locking balls 45 initially radially outward until the locking groove 44 reaches the locking balls 45.

Claims (11)

1. Screwing implement for tightening screws into workpieces, with an output shaft (10) which can be driven from an electric drive motor (7), with a tool-receiving socket for a rotating tool (13), which faces the front (12) of the implement, is coaxial with the output shaft (10) and is mounted on the output shaft or on a tool carrier (11) connected non-rotatably, in particular releasably, to the output shaft (10), wherein the output shaft (10) is bearing-mounted for movement in the axial direction between a front, inactive position and a rear, active position and preloaded towards its front position by spring force, and with a depth-control stop (29) for limiting the thread engagement, wherein the screwing implement (1) comprises a switching device (33) for energising and de-energising the drive motor (7), which switching device is switchable by an operating section (34) following the movement of the output shaft (10), wherein the switching device (33) is in its off state preventing the energisation of the drive motor (7) in the front position of the output shaft (10) and in its on state permitting the energisation of the drive motor (7) in the rear position of the output shaft (10), characterised in that it is provided on its front side (12) with a depth-control stop (28) which is adjustable in the axial direction and which limits the thread engagement during the tightening process and abuts against the workpiece when the desired thread engagement is reached.
2. Screwing implement according to claim 1, characterised in that the switching device (33) is located to the rear of the output shaft (10) in the axial direction.
3. Screwing implement according to claim 1 or 2, characterised in that the switching device (33) is a non-contact switching device.
4. Screwing implement according to claim 3, characterised in that the switching device (33) comprises a Hall sensor.
5. Screwing implement according to any of claims 2 to 4, characterised in that the operating section (34) is located at the rear end face (35) of the output shaft (10).
6. Screwing implement according to any of claims 2 to 5, characterised in that the operating section (34) comprises a permanent magnet (36).
7. Screwing implement according to any of claims 1 to 6, characterised in that the output shaft (10) is driven from the side via gear train (21, 24), wherein the gear train includes an output gear (21) mounted on the output shaft (10) and the output shaft (10) passes through the output gear (21) while being movable in the axial direction between its front, inactive position and its rear, active position.
8. Screwing implement according to claim 7, characterised in that the output shaft (10) and the output gear (21) bear against each other by way of an inclined surface arrangement (27), so that a rotary movement of the output shaft (10) relative to the output gear (21) is superimposed on the movement of the output shaft (10) in the axial direction and in operation the output gear (21) applies to the output shaft (10), in addition to the torque driving the output shaft (10), an axial force directed towards the front.
9. Screwing implement according to claim 7 or 8, characterised in that the output shaft (10) is driven via a bevel gear train by means of a drive shaft (22) extending at right angles to the output shaft.
10. Screwing implement according to any of claims 1 to 9, characterised in that the spring force is applied by a coil spring (20), one end of which is fixed, while the other end is supported on the output shaft (10) or on a part (47) mounted on the output shaft (10).
11. Screwing implement according to claim 10, characterised in that the output shaft (10) comprises a plug-in recess (42) extending from its front end face (41) and having a polygonal cross-section along at least a part of its length and the tool carrier (11) comprises a plug-in shank (43) having a polygonal cross-section along at least a part of its length, in that a continuous latching groove (44) is formed on the plug-in shank (43), in that, in the region of the output shaft (10) which contains the plug-in recess (42), one or more latching bodies (45) distributed along the circumference and assigned to the latching groove (44) are each mounted for movement in the radial direction in a radial recess (46) extending in the radial direction from the outer circumference of the output shaft (10) to the plug-in recess (42), and in that a locking sleeve (47) which is axially displaceable on the outer circumference of the output shaft (10) and on which the coil spring (20) is supported is assigned to the at least one latching body (45), so that a forward-acting spring force is applied to the locking sleeve (47), wherein the locking sleeve (47) has a locating surface (48) which rises towards the front and in a radially outward direction and acts against the at least one latching body (45), by way of which locating surface the locking sleeve (47) holds the at least one latching body (45) radially inwards in a locking position engaging the latching groove (44), and by way of which locating surface a releasing force pushing the locking sleeve (47) towards the rear against spring force is applied to the locking sleeve (47), if a forward-oriented tensile force is applied to the tool carrier (11), so that the rear flank of the latching groove (44) pushes the at least one latching body (45) outwards against the locating surface (48).

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