EP1814699B1 - Assembly for an electric tool and electric tool equipped with the assembly - Google Patents

Abstract

The invention relates to an electric tool and a module (1) for an electric tool, in particular an electric hand tool, such as a drill hammer with a chisel function, equipped with a module of this type. The module is configured as a synchronisation and switching unit that can be pre-assembled and is used for a rotary switch (12) that activates different operating modes. Said module comprises a locking element (3) that engages in a non-positive fit in a part that rotates in a fixed manner with a tool spindle (29), in addition to at least one switching plate (5, 6) with a guide curve (14, 15) for converting a rotational displacement of the rotary switch (12) into an axial displacement for activating different operating modes. The invention permits a simplified assembly of the electric tool.

Description

The invention relates to a structural unit for a power tool according to the preamble of claim 1. A building according to the preamble of claim 1 is known from DE 44 06 841 C1 known.

It is generally known that power tools, such as rotary hammers to design so that they are composed of modules. The individual units can be inexpensively prefabricated and assembled with a few assembly steps to the final product. Typical examples of such units are motor and gear units, which are used in prefabricated state in the housing shells of the tool. In power tools with a variety of functions, such as drill bits with chisel function, a high assembly cost is still required due to the complexity. Especially the setting of the different operating modes requires a high mechanical effort.

From the DE 42 05 840 C2 a hammer drill with chisel function is known in which different operating modes are switchable by means of a slide switch. In the known rotary hammer the chisel function is realized in that a rotationally fixed with the drill spindle fixed output gear is axially displaced into a locking position with a housing-fixed locking element. To relativize the possibility of intermediate positions in which the teeth of the locking element are aligned with the teeth of the output gear so that the output gear can not be brought into engagement with the locking element is provided in the known hammer drill that the locking teeth of the locking element first tapers and then gradually widening are formed, so that the output gear of the rotary drive moves even for the desired engagement in the locking element.

From the DE 195 45 260 A1 a hammer drill is known in which the different operating modes are switchable by means of a rotary switch, wherein the rotational movement of the rotary switch is converted via a switching plate in an axial movement. The switching plate is slidably mounted in the housing and is moved via an eccentrically arranged on the rotary switch cams. In order to block the drill spindle in the chisel operation, a locking plate fixed to the transmission housing is provided in the known rotary hammer, the toothed area by engaging with the teeth of the output gear of the drill spindle, this holds against rotation. In a "toothed tooth position" between locking plate and output gear, the latter can not be moved into the locking position.

From the DE 100 41 410 A1 as well as the EP 1 157 788 A2 generic rotary hammers are known with chisel function, the units as preassembled synchronization and switching units for a rotary switch for switching different modes of operation and a locking element for positive engagement in a rotationally fixed to a tool spindle rotating part and at least one switching plate with a guide curve for converting a rotational movement of the rotary switch in an axial movement for switching different operating modes include.

The invention has for its object to propose a structural unit for a power tool, is ensured by the simple assembly of the power tool.

This object is solved by the features of claim 1.

Advantageous embodiments of the invention are specified in the subclaims.

Due to the features of the dependent claim 7, a power tool, in particular electric hand tool such as hammer drill with chisel function, proposed, which is easy to assemble.

The invention is based on the idea to provide a preassemblable unit in the form of a synchronization and switching unit for a knob for switching different modes of operation, on the one hand has a locking element, with a rotating with the tool spindle part, in particular the driven gear to realize a chisel function can be held, and on the other hand provided with a switching plate with switching curve for converting a rotational movement of the rotary switch in an axial movement for switching different operating modes. The installation of a power tool, which is equipped with a inventive, preassembled unit is compared to the assembly of known power tools significantly simplified because the components, such as locking element and shrouds not individually bolted to the housing or must be used in special guides in the housing.

In order to move the shifters in the axial direction, eccentric cams are arranged on the rotary switch with respect to the axis of rotation of the rotary switch, which cooperate with the switching curves of the shifters.

It is provided that the assembly comprises two, preferably arranged parallel to each other, axially displaceable button, wherein a switching plate for connecting and disconnecting the percussion drive and a switching plate for axial displacement of a driven gear is formed on the tool spindle. By the axial displacement of the output gear, the drill drive can be switched on and off by the driven gear is brought into engagement or out of engagement with the drive gear of a countershaft. At the same time, the output gear can be brought into engagement with the locking element via this switching plate to realize the chisel function. Likewise, the output gear is movable with this switching plate in an axial position in which it is not in engagement with the drive gear of the countershaft and on the other hand is not yet locked by means of the locking element. In this so-called chisel position search position, the desired angle of rotation of the bit can be selected in which the output gear is to be blocked in a further switching position.

According to the present invention, the locking element for the perception of Bohrspindelarretierung in the chisel function is designed so that it engages in a larger number of gear gaps of a driven gear on the drill spindle, for example via a quarter circle or an eight-circle to secure the bit position wear.

According to the invention it is provided that the structural unit comprises a guide rod, along which the locking element and the shrouds are axially displaceable against a respective spring force. Characterized in that the locking element is not fixed in its position, but is arranged axially displaceable against a spring force, a synchronization device between the output gear and locking element is created in a surprisingly simple and effective manner. In the event that during the axial movement of the locking element along the drill spindle in the locking position, the teeth of the locking element should be aligned with the teeth of the output gear, the locking element is axially displaced against the spring force. As soon as only minimal torque acts on the drill spindle when the impact drive starts, it is slightly twisted, as a result of which the locking element with the locking teeth enters the tooth spaces the output gear snaps. In this way, the rotary switch and forcibly guided in this direction switching plate can be switched through in the bit position (lock position), even if the driven gear can not be brought into engagement with the locking element due to its angular position.

The installation of the assembly in a power tool can be done simply by the fact that the guide rod is received with its two end in a respective bearing in the housing, in particular is locked.

Due to the axial Federkraftbeaufschlagung the shifters also a synchronization device is created. If the output gear wheel can not be brought into engagement with the drive gear of a countershaft because of its angular position, the rotary switch can still be rotated into the corresponding position due to the design according to the invention. Once the rotary drive is turned on, the driven gear snaps into meshing engagement with the drive gear of the countershaft due to the axial spring loading. In the same way, the connection and disconnection mechanism for the percussion drive can be synchronized if the switching plate provided for the circuit of the percussion drive is designed to be axially spring-loaded. Due to the inventive design, the shifters are forced out only in one direction of movement, so that a switching of the knob regardless of the angular position of the gears or coupling elements to each other, is possible. The shift plate, which moves the output gear axially, should be spring-loaded such that the output gear is spring-loaded in the direction of the drive gear, so that the shift plate is forced out of the rotational drive position out only.

The same applies to the switching plate, which is responsible for the connection and disconnection of the percussion drive. Also, this switching plate should be forced out only from the engaged position. For this purpose, it is advantageous if all the springs of the assembly are arranged such that the direction of the spring force on the axially displaceable locking element and the spring force on at least one, preferably all, axially movable shifters are rectified.

The realization of the assembly with as few individual parts is possible, that the locking element and at least one switching plate in each case a coaxially arranged to the shift rod spring, preferably coil spring assigned, each coil spring with one end on a arranged on the shift rod stop, in particular a Circlip, supports. It is advantageous if the stop for the switching plate associated with a spiral spring simultaneously forms an axial stop for the locking element and / or the stop for a switching plate associated coil spring simultaneously forms an axial stop for another switching plate.

Preferably, the locking teeth are arranged symmetrically with respect to a central axis which is perpendicular to a longitudinal axis of the guide rod. This ensures that the locking element is acted upon symmetrically with respect to the guide rod and can not be twisted or tilted against it.

Preferably, a headband may be provided which fixes the shift plate in the drilling position and thus holds the drive gear in its position. This prevents that in case of a shock load of the tool or a triggering the slip clutch, the output gear, which is otherwise held by the coil spring in position, can escape and disengage.

A particularly resilient and low-wear locking element according to the invention is obtained when the locking element is produced by means of the metal injection molding method (MIM). Here, metal powder is first mixed with plastic powder and injected into a mold, whereupon the plastic is baked.

The invention will be explained in more detail below with reference to the figures showing an embodiment.

Fig. 1

eine Seitenansicht der Baueinheit mit Drehschalter,

Fig. 2

eine in Bezug auf Fig. 1 um 90° gedrehte Ansicht der Baueinheit,

Fig. 3

eine perspektivische Ansicht des vorderen Teilbereichs eines Bohrhammers in der Schalterstellung "Bohren mit Schlagantrieb" (Bohrhämmern),

Fig. 4

eine perspektivische Ansicht des vorderen Teilbereichs eines Bohrhammers in der Schalterstellung Bohren ohne Schlagantrieb",

Fig. 5

eine perspektivische Ansicht des vorderen Teilbereichs eines Bohrhammers in der Schalterstellung "Meißeln" bei arretierter Bohrspindel,

Fig. 6

eine perspektivische Ansicht des vorderen Teilbereichs eines Bohrhammers in der Schalterstellung "Meißeln" bei einer "Zahn-auf-Zahn-Stellung" zwischen.Abtriebszahnrad und Arretierelement,

Fig. 7

eine perspektivische Ansicht des vorderen Teilbereichs eines Bohrhammers in der Schalterstellung "Meißelpositionssuche" und

Fig. 8

Baueinheit in der Schalterstellung "Bohren" mit zusätzlichem Haltebügel

Showing:

Fig. 1

a side view of the assembly with rotary switch,

Fig. 2

one in relation to Fig. 1 90 ° rotated view of the unit,

Fig. 3

a perspective view of the front portion of a hammer drill in the switch position "drilling with impact drive" (drills),

Fig. 4

a perspective view of the front portion of a hammer drill in the switch position drilling without impact drive ",

Fig. 5

a perspective view of the front portion of a hammer drill in the switch position "chiseling" with locked drill spindle,

Fig. 6

a perspective view of the front portion of a hammer drill in the switch position "chiselling" at a "tooth-on-tooth position" between.Abtriebszahnrad and locking element,

Fig. 7

a perspective view of the front portion of a rotary hammer in the switch position "chisel position search" and

Fig. 8

Assembly in switch position "drilling" with additional retaining bracket

The structural unit 1 according to the invention consists of a guide rod 2 on which a locking element 3 with locking teeth 4, as well as a first switching plate 5 and a second switching plate 6 are mounted axially displaceably.

The guide rod 2 is guided for this purpose by an integrally formed with the locking element 3 bearing sleeve 7. The shift plates 5, 6 are arranged parallel to one another and in each case held captive and displaceable on the guide rod 2 via lugs 8, 9, 10, 11 oriented orthogonally to the shift plates 5, 6, the guide rod 2 being guided through a through opening in the lugs 8, 9, 10, 11 is guided. The second switching plate 6 is arranged between the first switching plate 5 and a rotary knob 12, wherein the second switching plate is provided with a 90 ° angled and parallel to the guide rod 2 extending connecting plate 13 which engages over the first switching plate 5 and the second switching plate 6 with the Tabs 10, 11 connects. To shorten the length of the assembly 1, the tab 10 of the second Shifter plate 6 between the tabs 8, 9 of the first shift plate on the guide rod 2 is arranged.

Each switching plate 5, 6 has a guide curve 14, 15, which cooperate with a respective transverse to the guide rod 2 extending cam 16, 17 of the rotary switch 12.

In the in Fig. 1 In the embodiment shown, the first switching plate 5 is displaced against the spring force of a spiral spring 18 on the guide rod 2 in the direction of the locking element 3. The cam 17 is in the switch position shown not engaged with the associated guide cam 15. The shrouds 5, 6 are positively guided only in one axial direction.

The locking teeth 4 of the locking element 3 are arranged over a circular segment. The locking element 3 is located in the in Fig. 1 illustrated embodiment of a, held in a groove of the guide rod 2 retaining ring 19 which forms an axial stop for the locking element 3, to. The retaining ring 19 simultaneously forms a stop for the coil spring 18 of the first switching plate 5, whereby the coil spring 18 is supported on the retaining ring 19 and on the tab 8.

The locking element 3 is associated with a coaxial with the guide rod 2 and the bearing sleeve 7 arranged coil spring 20 which is supported at one end to a held in a circumferential groove of the guide rod 2 retaining ring 21 and with its other end laterally on the locking element 3. To facilitate assembly of the assembly are on the locking element 3 two axially and parallel to the guide rod 2 extending Bolt 22, 23 provided, which can engage in corresponding recesses in the housing.

The second switching plate 6 is associated with a coil spring 24 which, like all coil springs 18, 20 coaxial with the guide rod 2 is arranged. The coil spring 24 is supported on a retaining ring 25 held in a groove of the guide rod 2 and laterally on the tab 10 of the second control panel 6. The securing ring 25 simultaneously forms an axial stop for the first switching plate 5. The axial stop for the second switching plate 6 is formed by a securing ring 26.

In the FIGS. 3 to 7 is only partially shown the front portion of a hammer drill. On the representation of the drive motor and on the representation of housing parts has been omitted for clarity. The drive motor, not shown, is connected to a countershaft 27 via a shaft 28 in fixed rotational engagement, wherein the countershaft 27 causes both the rotary drive for the drill spindle 29 and the percussion drive. The impact drive is realized by means of a conventionally configured wobble bearing 30, which acts via a wobble finger on a piston of a striking mechanism. The countershaft 27 is guided centrally through the swash bearing 30 and rotatably supported relative thereto. The swash bearing 30 can be brought via a jaw clutch 31 in rotationally fixed engagement with the countershaft 27, as for example in Fig. 3 is shown. For this purpose, the dog clutch 31 on the countershaft 27 axially displaceable and rotationally fixed on this mounted coupling sleeve 32 with two axially projecting coupling cam 33 which can engage in corresponding grooves of a coupling counterpart 35. The coupling piece 35 is rotatably connected to the swash bearing 30.

The second switching plate 6 engages with the tab 10 in a circumferential groove 36 of the coupling sleeve 32, whereby the second switching plate 6 and the coupling sleeve 32 of the dog clutch 31 can perform a coupled axial movement.

On the countershaft 27, a drive gear 37 is arranged rotationally fixed, which in Fig. 3 meshes with a driven gear 38. The output gear 38 is rotatably mounted on the drill spindle 29. For safety reasons, however, a slip clutch 39 is provided in a known manner in order to avoid injuries when tilting the drill during the drilling operation. The slip clutch and thus the output gear 38 and the first shift plate 5 are coupled together in the axial direction. For this purpose, the first switching plate 5 engages with the tab 8 in a circumferential groove 40 of the slip clutch 39, so that the output gear 38 is indeed rotatable relative to the unit 1, but in the axial direction of movement is positively connected to the first switching plate.

About the rotary switch 12 and the unit 1 different operating modes can be switched. The rotational movement of the rotary switch 12 is converted via the cams 16, 18 in conjunction with the guide curves 14, 15 in axial movements of the shifters 5, 6 and thus of the output gear 38 and the coupling sleeve 32 of the dog clutch 31.

In the following, the different operating modes based on the Fig. 3 to 7 explained in more detail.

In Fig. 3 is the operating mode "drilling with impact drive" (drill hammers) shown. The shifters 5, 6 are with the tabs 8, 11 on the retaining rings 25, 26, whereby the output gear 38 of the drill spindle 29 meshes with the drive gear 37 of the countershaft 27, which in turn transmits the rotary motion of the drive gear 37 via the output gear 38 to the drill spindle 29 (drilling). At the same time, the dog clutch 31 is closed. The coupling sleeve 32 engages with the coupling cam 33 in grooves of the coupling counterpart of the swash bearing 30, whereby the rotational movement of the countershaft 27 is transmitted to the swash bearing 30, which in turn acts a tumble finger on a percussion piston, not shown (hammering).

In Fig. 4 the rotary switch 12 is rotated in the switching position "drilling", whereby the opposite Fig. 3 the second switching plate 6 was displaced axially against the spring force of the spring 24 on the guide rod 2 in the direction of locking element 3 by the cam 17 was moved along the guide curve 15. The forcibly coupled to the second switching plate coupling sleeve 32 has been correspondingly moved axially along the countershaft 27 in the direction of drive gear 37, whereby the coupling cam 33 of the coupling sleeve 32 out of the grooves 36 of the coupling counterpart 35 were herausverfahren. Thus, the rotational movement of the countershaft 27 is no longer transferred to the swash bearing 30, so that the percussion drive is disabled. The axial position of the first shift plate 5 is opposite to in FIG Fig. 3 shown operating mode has not been changed, whereby the drive gear 37 continues to mesh with the output gear 38 of the drill spindle 29.

If now the rotary switch 12 of the in Fig. 4 shown switching position by 90 ° in the in Fig. 3 shown switching position is rotated back, the second switching plate 6 due to the spring force of the spring 24 back into the axially Fig. 3 moved position shown, wherein the clutch cam 33 engage in the grooves 34. Assuming the case that the clutch cam 33 should not be aligned with the grooves 34, the switch can still in the in Fig. 3 shown rotated position. However, the second shift plate 6 moves only so far in the axial direction until the switching cam 33 abut against the coupling counterpart 35. However, as soon as the countershaft 27 is then driven, the clutch cams 33 snap into the grooves 34 due to the spring loading with the coil spring 24 into the grooves 36. Due to the inventive design of the unit 1 so a synchronization for the connection of the percussion drive is created.

In Fig. 5 the switch has moved to the "chiseling" position. Opposite the in Fig. 3 shown operating mode, only the first shift plate 5 has been axially displaced in the direction of locking element 3 on the guide rod 2, whereby the output gear 38 coupled to the shift plate 5 has been axially displaced in the same direction. As a result, the output gear 38 no longer meshes with the drive wheel 37 of the countershaft 27, but with the locking teeth 4 of the locking element 3. In this mode, only the percussion drive is activated. The drill spindle 29 is prevented via the locking element 3 from rotating.

Fig. 6 shows the same switch position as in Fig. 5 , However, the driven gear 38 could not be engaged with the locking teeth 4 of the locking member 3 because the teeth of the driven gear 38 and the locking teeth 4 are aligned. As a result, the locking element against the in Fig. 5 shown position axially displaced towards the front end of the drill spindle 29 of the output gear 38. In this case, the coil spring 20 has been compressed. Due to the axial Displaceability of the locking element on the guide rod 2, it is even possible that the rotary switch in the in Fig. 6 shown rotational position is rotatable. Without displaceable mounting of the locking element 3, the axial movement of the driven gear 38 and thus the axial movement of the switching plate 5 and the rotational movement of the rotary switch 12 would be blocked. Due to the inventive design of the unit 1, the locking element 3 is biased against the driven gear 38, so that the locking teeth 4 of the locking element 3 snap into the tooth gaps of the output gear 38 as soon as a slight rotation of the drill spindle 29 takes place. Due to the resilient bias of the locking element, a synchronization device for the locking mechanism is thus provided.

In Fig. 7 the rotary switch 12 is rotated in the "bit position search position". In this case, the first shift plate 5 has been displaced axially, to such an extent that the output gear 38 is positioned in the axial direction between the drive gear 37 and the locking element 3. In this position, the rotary drive is decoupled. However, the drill spindle 29 with the output gear 38 is rotatable by hand, so that the desired bit position can be searched before the rotary switch 12 by another 45 ° in the in Fig. 5 shown "chisel position" is rotated.

Fig. 8 shows a headband 41, which is fastened with a mounting leg 42 to a housing flange 46. The retaining clip 41 has a securing leg 44, which engages around the switching plate 5 in a front abutment region 45. In this position, it is thus ensured that the slip clutch 39 is positively held in position via the groove 40 with the leg 8 of the control panel 5. Without such Retaining clip 41, the friction clutch 39 is merely frictionally held by the coil spring 18 on the locking ring 25, so that in the case of shock stress there is a risk that the output gear 38 comes out of engagement. An increase in the spring force to reduce this risk is eliminated because otherwise the switching forces are too high.

Upon actuation of the rotary switch 12 in the clockwise direction as viewed Fig. 8 runs the cam 16 on a release portion 43 of the securing bracket 41 so that it dodge down and the switching plate 5 releases before the cam 16 comes into contact with the guide cam 14.

LIST OF REFERENCE NUMBERS

1

unit

2

guide rod

3

locking

4

locking teeth

5

first switching plate

6

second switching plate

7

bearing sleeve

8th

flap

9

flap

10

flap

11

flap

12

rotary switch

13

connecting strap

14

guide curve

15

guide curve

16

cam

17

cam

18

spiral spring

19

circlip

20

spiral spring

21

circlip

22

bolt

23

bolt

24

spiral spring

25

circlip

26

circlip

27

Countershaft

28

wave

29

Spindle

30

wobble bearing

31

claw clutch

32

coupling sleeve

33

clutch cams

34

groove

35

Coupling counterpart

36

groove

37

drive gear

38

output gear

39

slip clutch

40

circumferential groove

41

headband

42

fastening leg

43

release section

44

securing legs

45

plant area

46

housing flange

Claims (11)

1. A structural unit for an electrical tool, in particular an electrical tool such as a hammer drill with a chisel function, wherein the structural unit (1) is designed in the form of a synchronization and switching unit capable of being pre-assembled for a rotary switch (12) for switching different modes of operation, and a guide rod (2) and at least one contact plate (5, 6) with a guide curve (14, 15) for converting a rotary movement of the rotary switch (12) into an axial movement for switching different modes of operation, wherein the structural unit (1) has two axially displaceable contact plates (5, 6) preferably arranged parallel to each other, wherein one contact plate (6) is designed for switching an impact drive on and off and one contact plate (5) is designed for the axial displacement of a driven gearwheel (38) on the tool spindle (29), characterized in that the structural unit (1) has a locking element (3) with a plurality of locking teeth (4) extending over a circular segment for engaging with positive locking in a part rotating in a rotationally fixed manner with a tool spindle (29), and the locking element (3) and the contact plates (5, 6) are held by the guide rod (2), wherein both the locking element (3) and the contact plates (5, 6) are displaceable axially along the guide rod (2) against a spring force in each case.
2. A structural unit according to claim 1, characterized in that in order to produce the spring force springs (18, 20, 24) are arranged in such a way that the direction of the spring force is directed in the same way both at the locking element (3) and at the at least one contact plate (5, 6).
3. A structural unit according to one of the preceding claims, characterized in that one spiral spring (18, 20, 24) arranged coaxially with the guide rod (2) is associated in each case with the locking element (3) as well as with the at least one contact plate (5, 6), wherein each spiral spring (18, 20, 24) is supported at one end on a stop (19, 21, 25), in particular a retaining ring, arranged on the guide rod (2).
4. A structural unit according to claim 3, characterized in that the stop (19) for the spiral spring (18) associated with the contact plate (5) forms an axial stop for the locking element (3) at the same time.
5. A structural unit according to one of claims 3 or 4, characterized in that the stop (25) for the spiral spring (24) associated with the contact plate (6) forms an axial stop for the further contact plate (5) at the same time.
6. A structural unit according to any one of the preceding claims, characterized in that the locking teeth (4) are arranged symmetrically with respect to a centre axis which extends at a right angle to a longitudinal axis of the guide rod (2).
7. An electrical tool, in particular an electrical hand tool such as a hammer drill with a chisel function, with a rotary switch for switching different modes of operation, characterized in that the rotary switch (12) engages with a structural unit (1) according to any one of the preceding claims, in order to convert a rotary movement of the rotary switch (12) into an axial movement for switching different modes of operation.
8. An electrical tool according to claim 7, characterized in that a switching cam (16, 17), which is capable of being moved along the guide curve (14, 15) of the contact plate (5, 6) in each case, is provided on the rotary switch (12) for each contact plate (56) [sic], wherein the contact plates (5, 6) and the locking element (3) are spring-loaded axially in the direction of the rotary switch (12).
9. An electrical tool according to one of claims 7 or 8, characterized in that the rotary switch (12) is rotatable into switching positions distributed over the periphery, wherein the modes of operation of drilling, hammer-drilling, chiselling and chisel position searching are capable of being switched on.
10. An electrical tool according to any one of claims 7 to 9, characterized in that the rotary switch (12) engages in the switching positions in a releasable, and in particular an audible, manner.
11. An electrical tool according to any one of claims 7 to 10, characterized in that the contact plate (5) is capable of being fixed axially by a holding yoke (41) capable of being activated by way of the rotary switch (12).

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