EP2813702B1 - Working machine with a combustion engine - Google Patents

Description

The invention relates to a working device with an internal combustion engine of the type specified in the preamble of claim 1.

From the DE 33 08 400 A1 is a generic working device, namely a power saw known, which has a starting device. To ensure that the chain is braked when the starting device is in the starting position, a connection between a throttle holding part of the starting device and the braking device is provided. When inserting the starting position, the braking device is actuated and adjusted to the braked position.

From the US 3,664,390 A a chain saw with a braking device and an ignition device is known. The chainsaw has a lever which, in an actuated position, both interrupts the ignition and acts on a brake shoe which brakes a brake drum of the chain saw.

From the US 3,982,616 goes out a working device whose engine drives a drive pinion via a centrifugal clutch. The safety clutch decouples the drive pinion from the centrifugal clutch. In addition, a braking device is provided for braking the drive pinion.

The FR 2 570 017 A2 discloses a power saw with means for detecting contact of the operator with the saw chain. The detection system comprises a pivoting lever which moves from an electrical actuator into the path of movement of fingers on the Clutch drum is pivoted when a contact of the operator was determined with the saw chain. The pivot lever is taken on the fingers on the clutch drum and adjusted to a position in which the pivot lever actuates a pawl. The pawl releases a tensioning device for the brake band, so that the saw chain is braked.

The WO 2013/015779 A2 shows a Anwerfvorrichtung for the internal combustion engine of a working device. The starter device can be operated via a cable. However, the Anwerfvorrichtung also includes an electric motor which is provided for mounting a starter spring.

The US 2012/0318236 A1 shows a starting device for an internal combustion engine. About a mode selector a hot start position and a cold start position of the throttle element and choke element are adjustable.

The US 2011/0048359 A1 and the US 2002/0185352 A1 show Anwerfvorrichtungen for an internal combustion engine. To connect to the crankshaft is in the US 2002/0185352 A1 a coupling mechanism provided with pawls.

The invention has for its object to provide a working device with an internal combustion engine of the generic type, in which it is ensured in a simple manner that the tool is not driven when starting the implement.

This object is achieved by a working device with an internal combustion engine with the features of claim 1.

To ensure in a simple manner that the tool can not run, a blocking device is provided with a pawl which projects in an actuated position in the path of movement of the driven element and limits the rotation of the driven element to less than one revolution. The starting device has an actuating device for the blocking device. In the starting position of the starting device, the blocking device holds the pawl in the actuated position. Since the output element in start position the starting device is blocked by the pawl, the output element of the clutch can not rotate. As a result, a drive of the tool is prevented in a simple manner. A pawl can securely lock the output element and absorb relatively large forces. The blocking device can be structurally simple, resulting in a simple construction of the implement. Since the starting means for starting the internal combustion engine is moved to the starting position, the internal combustion engine does not run when adjusting the pawl in the actuated position, and the forces exerted by the output member on the pawl forces are low.

The blocking device is advantageously adjusted when inserting the starting position in the actuated position. The actuating movement when inserting the starting position is therefore used to adjust the blocking device in the actuated position. The pawl is in particular pivotally mounted. This results in a simple structure, and for adjusting the pawl in the actuated position only low actuation forces are required.

The pawl is advantageously spring-loaded by a return spring in the direction of the unactuated position of the blocking device. The starting device adjusts the pawl, in particular against the force of the return spring in the actuated position. The return spring ensures that the pawl can be returned to the unactuated position when the starting position is in its operative position. The reset of the starting device in the operating position and the reset of the pawl can be done independently due to the return spring. Advantageously, the connection between the actuating device and the pawl is designed so that the actuating device can adjust the pawl only in the direction of the actuated position. The movement of the actuator back into the operating position of the starting device associated position advantageously causes no provision of the pawl.

Advantageously, a damping spring is arranged in operative connection between the actuating device and the pawl. The damping spring dampens the contact of the Pawl with the output member when the actuator is moved to the starting position while the output member is already rotating. The damper spring also allows for adjustment of the actuator even if the pawl can not be adjusted to the actuated position. This is especially the case when the pawl is blocked by the output element itself, for example due to an unfavorable rotational position of the output element. The pawl applies in this case under bias to the output element. As soon as the output element begins to rotate and moves out of the rotational position, the pawl can be pivoted into its actuated position, so that further rotation of the output element is avoided. Even with unfavorable rotational position of the output element is thereby prevented that the output member can rotate more than one revolution.

Advantageously, the blocking device has a holding contour which holds the pawl in the drive direction loaded output element regardless of the position of the starting device in the actuated position. To reset the pawl in the unactuated position is therefore in addition to the adjustment of the locking device in the operating position also necessary that the output element is not loaded in the drive direction. This prevents a jerky acceleration of the tool when releasing the starting device. As long as the output element is loaded in the drive direction, the pawl remains in its actuated position. Only when the output element is not loaded in the drive direction, the pawl can be adjusted back into its actuated position in particular due to the force of the return spring. Instead of the return spring, the pawl can also be reset by the operator. Due to the holding contour of the operator after adjusting the starting device in the operating position initially set a speed below the Einkuppeldrehzahl, in particular the idle speed, so that the pawl is returned to its unactuated position or can be reset. Only then is the output element released, and the implement can be operated in the usual way.

A simple constructive structure is obtained when the pawl cooperates in blocking the output element with a receptacle of the output element. The output element in particular has a plurality of rotationally symmetrical to the axis of rotation of the driven element arranged recordings. As a result, the possible rotational movement of the output element can be limited to significantly less than one revolution of the output element. Two recordings have proved to be particularly advantageous.

Advantageously, the blocking device blocks an insertion of the starting position with a rotating output element. As a result, inserting the starting position during operation, that is to say when the internal combustion engine is running, can be avoided in a simple manner. A simple design results when the blocking device has a non-rotatably connected to the output element blocking contour, the force of rotation on the pawl in the direction of their with rotating output element and moving from the unactuated position toward its actuated position pawl above a design speed unconfirmed position. A simple construction results when the locking contour is adjacent to the receptacle on the outer side and the rearward direction of the receptacle relative to the axis of rotation. The locking contour is in particular firmly connected to the output element. At speeds above the design predetermined speed exerts the locking contour on the pawl a force in the direction of the unactuated position of the pawl. The blocking contour is advantageously arranged on the outside of the axis of rotation and on the outside in the drive direction of the receptacle adjacent to the receptacle. This results in a simple structural design. To the speed at which the locking contour is effective, largely free to provide design, can also be provided that the locking contour is formed on a driven element held on the flyweight, which covers the recording at speeds above the design predetermined speed at least partially. The recording is at least so far covered that the pawl can not be adjusted to its actuated position or is held by the retaining contour is not in the actuated position.

The starting position of the starting device is advantageously achieved by actuating a throttle lever of the working device. The pawl can still remain in its actuated position. The clutch is in particular a centrifugal clutch, and the output member comprises a clutch drum.

Fig. 1

eine schematische Seitenansicht eines Arbeitsgeräts,

Fig. 2

eine schematische Schnittdarstellung durch das Arbeitsgerät aus Fig. 1,

Fig. 3

eine schematische Darstellung einer Starteinrichtung des Arbeitsgeräts in Betriebsstellung,

Fig. 4

die Starteinrichtung aus Fig. 3 in einer Startstellung,

Fig. 5

eine schematische Darstellung einer Blockiereinrichtung des Arbeitsgeräts in betätigter Stellung einer Sperrklinke,

Fig. 6

die Blockiereinrichtung aus Fig. 5 mit der Betätigungseinrichtung in einer Betriebsstellung,

Fig. 7

die Blockiereinrichtung aus den Fig. 5 und 6 in unbetätigter Stellung der Sperrklinke,

Fig. 8 und Fig. 9

Ausführungsbeispiele von Blockiereinrichtungen in unbetätigter Stellung der Sperrklinke,

Fig. 10

ein Ausfiihrungsbeispiel der Blockiereinrichtung in betätigter Stellung der Sperrklinke,

Fig. 11

die Blockiereinrichtung aus Fig. 10 mit blockiertem Abtriebselement,

Fig. 12

die Blockiereinrichtung aus Fig. 11 mit der Betätigungseinrichtung in

-

Betriebsstellung ,

Fig. 13

die Blockiereinrichtung aus Fig. 12 mit der Sperrklinke in unbetätigter Stellung,

Fig. 14 bis Fig. 17

ein weiteres Ausfiihrungsbeispiel einer Blockiereinrichtung in den Fig. 10 bis 13 entsprechenden Stellungen.

Embodiments of the invention are explained below with reference to the drawing. Show it:

Fig. 1

a schematic side view of a working device,

Fig. 2

a schematic sectional view through the implement from Fig. 1 .

Fig. 3

a schematic representation of a starting device of the working device in the operating position,

Fig. 4

the starting device off Fig. 3 in a starting position,

Fig. 5

a schematic representation of a blocking device of the working device in the actuated position of a pawl,

Fig. 6

the blocking device off Fig. 5 with the actuating device in an operating position,

Fig. 7

the blocking device from the FIGS. 5 and 6 in the unactuated position of the pawl,

FIGS. 8 and 9

Embodiments of blocking devices in the unactuated position of the pawl,

Fig. 10

an embodiment of the blocking device in the actuated position of the pawl,

Fig. 11

the blocking device off Fig. 10 with blocked output element,

Fig. 12

the blocking device off Fig. 11 with the actuator in

-

Operating position,

Fig. 13

the blocking device off Fig. 12 with the pawl in the unactuated position,

FIGS. 14 to 17

a further exemplary embodiment of a blocking device in the Fig. 10 to 13 corresponding positions.

Fig. 1 shows as Ausfiihrungsbeispiel for a working device with an internal combustion engine, a hand-held implement, namely a chainsaw 1. The chainsaw 1 has a housing 2, on which a rear handle 3 and a handle tube 4 are fixed. On the housing 2, a hand guard 5 is also pivotally mounted, which can serve to trigger a chain brake device of the power saw 1. At the side facing away from the rear handle 3 of the housing 2 projects a guide rail 6 forward, on which a saw chain 7 is arranged circumferentially. The saw chain 7 is of an in Fig. 2 driven schematically shown internal combustion engine 11. As Fig. 1 shows, a throttle lever 8 and a throttle lock 9 are pivotally mounted on the rear handle 3. Adjacent to the rear handle 3, a mode selector 10 protrudes from the housing 2, in the direction of an arrow 23 from the in Fig. 1 shown operating position 81 can be adjusted in a dashed line start position 80.

Fig. 2 shows the structure of the drive of the power saw 1 in detail. The power saw 1 has a starter device 21, which is advantageously designed as a pull starter. The Anwerfvorrichtung 21 acts on a crankshaft 12 to which a fan 20 is held against rotation. In the exemplary embodiment, the fan 20 is disposed between the Anwerfvorrichtung 21 and a crankcase 17 of the engine 11. The internal combustion engine 11 has a cylinder 16 in which a piston 18 is reciprocated. The piston 18 rotatably drives the crankshaft 12 via a connecting rod 19. The crankshaft 12 is rotatably mounted in the crankcase 17 about a rotation axis 41. On the opposite side of the fan 20 of the engine 11, a clutch 13 is arranged, which is formed in the embodiment as a centrifugal clutch. In Fig. 2 the coupling 13 is shown schematically. The clutch 13 has a drive element 63, which comprises at least one flyweight. When a constructive predetermined speed of the crankshaft 12 is exceeded, the flyweight moves radially outward and comes to rest on an output element 51. On the outer circumference of the output element 51, a brake band 15 is arranged, which is part of the triggered by the hand guard 5 braking device. On the output element 51, a drive pinion 22 is fixed, which drives the saw chain 7.

The internal combustion engine 11 is connected via an in Fig. 3 shown carburetor 24 supplied fuel / air mixture. The internal combustion engine 11 is in particular a single-cylinder engine, advantageously a two-stroke engine. The carburetor 24 has a carburetor housing 34 in which a Ansaugkanalabschnitt 25 is guided. In the intake passage section 25, a throttle valve 26 and a choke flap 27 are pivotally supported. Instead of the throttle valve 26 and the choke flap 27, other throttle elements may be provided in the intake passage section 25 formed in the carburetor 24. The throttle valve 26 is pivotally mounted with a throttle shaft 28 about a rotation axis 32. The choke flap 27 is pivotally mounted with a choke shaft 29 about a rotation axis 33. At the throttle shaft 28, a throttle lever 30 is fixed. The throttle lever 30 is advantageously rotatably connected to the throttle shaft 28. At the choke shaft 29, a choke lever 31 is fixed. The choke lever 31 may be rotatably connected to the choke shaft 29, as shown in the embodiment. For tolerance compensation, however, a small relative movement between the choke lever 31 and the choke shaft 29 may be possible.

The mode selector 10 is coupled to the choke lever 31 via a coupling rod 36. The mode selector 10 is pivotally mounted about a pivot axis 50. The mode selector 10, the coupling rod 36, the choke lever 31, the choke shaft 29 and the choke flap 27 are part of a starting device 39. In the in Fig. 3 In the operating position 35, the choke flap 27 reduces the flow cross-section in the intake passage section 25 not or only slightly. The choke flap 27 is approximately parallel to the flow direction in the intake passage section 25.

To the starting device 39 from the in Fig. 3 shown operating position 35 in the in Fig. 4 shown starting position 42 to adjust the throttle lever 30 in the direction of arrow 37 in Fig. 3 pivoted. As a result, a portion of the throttle lever 30 pivots out of the pivotal path of the choke lever 31. The throttle lever 30 is pivoted by operating the throttle lever 8 in the direction of the arrow 37. Subsequently, the mode selector 10 can be pivoted in the direction of the arrow 70. Thereby pivots the choke lever 31 in the direction of arrow 38 in the in Fig. 4 When the throttle lever 8 is released when the mode selector 10 is actuated, the throttle lever 30 locks with the choke lever 31. The throttle lever 30 engages a shoulder 40 of the choke lever 31. In the in Fig. 4 shown starting position 42, the throttle valve 26 is slightly open and the choke flap 27 against the operating position 35 further closed. Throttle valve 26 and choke flap 27 are in a position in which the amount of combustion air supplied to the internal combustion engine 11 and the quantity of fuel supplied to the internal combustion engine 11 are adjusted to the air consumption and the fuel consumption when the internal combustion engine 11 is started, that is to say when the starting device 21 is actuated , It can also be provided that only the choke lever 31 must be actuated and this provides the throttle lever 30 in a starting position.

In order to avoid that the tool, so the saw chain 7 can move when starting the engine 11, is an in Fig. 5 schematically shown blocking device 43 is provided. The blocking device 43 comprises a pawl 44, which is mounted pivotably about a pivot axis 58 and which cooperates with a receptacle 53 on the output element 51. The output element 51 comprises a clutch drum 14. On the clutch drum 14, a holding plate 52 is fixed, which protrudes on opposite sides over the outer circumference of the clutch drum 14 and which has a receptacle 53 for the pawl 44 on both sides. Also, another constructive arrangement of one or more receptacles 53 may be advantageous. The output element 51 is driven by the internal combustion engine 11 in a drive direction 54. Fig. 5 shows the pawl 44 in its actuated position 46. In this position, the pawl 44 projects into the in Fig. 5 Dashed line of movement 71 of the output element 51 a. In this case, the movement path 71 is the circle which the region of the output element 51 furthest from the rotation axis 41 describes in the region of the receptacle 53 when rotating about the rotation axis 41.

At the pawl 44 an actuating element 57 engages. The actuating element 57 is of a return spring 55 in the direction of a in Fig. 7 shown unactuated position 47 of the pawl 44 spring-loaded. In the schematic representation in Fig. 5 the return spring 55 is supported at one end on a fixed bearing 56 connected to the actuator 57. The other end of the spring 55 is fixedly connected to the housing 2.

The mode selector 10 is firmly connected in the exemplary embodiment with a bearing shaft 48 and pivotally mounted about the pivot axis 50. On the bearing shaft 48, an actuating pin 49 is fixed, which acts on the actuating element 57. The mode selector 10 forms with the bearing shaft 48 and the actuating pin 49, an actuator 45 for the blocking device 43rd Fig. 5 shows the mode selector 10 in its starting position 80. In the starting position 80 of the mode selector 10, the starting device 39 is in its starting position 42 (FIG. Fig. 4 ). In start position 80 of the mode selector 10, the actuating pin 49 presses the pawl 44 against the force of the spring 55 in the actuated position 46th

If the starting position 42 is released by accelerating, the in Fig. 4 Locking shown between throttle lever 30 and choke lever 31. The mode selector 10 is due to the force of a spring not shown in his in Fig. 6 shown operating position 81 adjusted. It can also be provided that the mode selector 10 is selected by the operator from the in Fig. 5 Starting position shown 80 in the in Fig. 6 shown operating position 81 is reset. As Fig. 6 shows, a holding contour 59 is formed on the receptacle 53. The holding contour 59 limits the receptacle 53 on the radially outside of the axis of rotation 41 and in the drive direction 54 behind the area and lies in the pivoting path of the pawl 44 from the actuated position 46 in the in Fig. 7 shown unactuated position 47. The pawl 44 is spring-loaded by the spring 55 in the direction of the unactuated position 47. The spring force is in Fig. 6 indicated by the arrow 66. As long as the output element 51 is loaded in the drive direction 54, a pivoting of the locking pawl 44 is prevented in the unactuated position 47 of the holding contour 59 .

Fig. 7 shows the arrangement after the output element 51 is no longer loaded in the drive direction 54. This can be done, for example, that the operator releases the throttle lever 8 and the engine 11 is operated at idle. The idle speed is below the engagement speed of the clutch 13, so that the output element 51 of the clutch 13 is not driven further. Due to the force of the spring 55, the pawl 44 is pivoted in a pivoting direction 65 in its unactuated position 47 . In this case, the pawl 44 has exerted a force on the retaining contour 59 and the output element 51 slightly in a direction of drive 54 54 opposite direction of rotation moves. The retaining contour 59 causes the pawl 44 remains in its actuated position 46, to the output element 51 no torque in the drive direction 54 acts more. As a result, jerky starting of the tool when adjusting the starting device 39 into the operating position 35 can be prevented.

At the in Fig. 8 shown embodiment, a locking contour 60 is formed on the receptacle 53 adjacent to the retaining contour 59. The blocking contour 60 is arranged on the side of the receptacle 53, which lies radially on the outside relative to the axis of rotation 41 and on the rear side relative to the drive direction 54, adjacent to the receptacle 53. The blocking contour 60 exerts in the drive direction 54 rotating output element 51 on a from the unactuated position 47 in the direction of their actuated position 46 ( Fig. 6 ) moved pawl 44 a force in the direction of the arrow 72, ie, relative to the axis of rotation 41 radially outward. From a constructive predetermined speed followed by the two over the clutch drum 14 projecting ends of the holding plate 52 formed locking contours 60 so quickly that a pivoting of the pawl 44 in the actuated position 46 is no longer possible. The mode selector 10 can thereby not be adjusted to its starting position 80. As a result, an adjustment of the starting device 39 in the starting position 42 is prevented with a rotating output element 51.

At the in Fig. 9 shown alternative embodiment adjacent to the receptacles 53 flyweights 61 are mounted on the output member 51. In the in Fig. 9 shown outwardly adjusted position of the flyweights 61 close the centrifugal weights 61, the receptacles 53 at least partially. In the exemplary embodiment, the receptacles 53 are approximately completely closed. The flyweights 61 each have a locking contour 62 which closes a receptacle 53. As a result, an adjustment of the pawl 44 in the in Fig. 6 shown actuated position 46 prevents. The centrifugal weights 61 are connected via a respective bolt 74 with the holding plate 52, which projects into a groove 73. The groove 73 extends inclined to the radial direction to the rotation axis 41. By appropriate design of the inclination angle of the groove 73 and the weight of the centrifugal weight 61, the speed at which the adjustment of the pawl 44 is prevented in the actuated position 46 can be adjusted.

Fig. 10 shows an embodiment of a blocking device 43. The design of the output element 51 corresponds to the design of the output element of the Fig. 5 to 7 , Also a design according to the embodiment according to Fig. 8 or according to the embodiment according to Fig. 9 with a locking contour 60 or 62 may be advantageous. Like reference numerals indicate corresponding elements throughout the figures. The actuator 45 of in Fig. 10 embodiment shown instead of a mode selector 10 has a rotatably mounted about the pivot axis 50 knob 67. Advantageously, the knob 67 in addition to its rotational movement in the direction of the pivot axis 50 is longitudinally displaceable. On the knob 67, a cantilevered arm 75 is arranged, on which one end of a damping spring 68 is fixed. The other end of the damping spring 68 is connected to the pawl 44. The damping spring 68 is designed as a tension spring. Also, another structural arrangement and design of acting between the knob 67 and the pawl 44 damping spring 68 may be advantageous. In Fig. 10 the pawl 44 is in the actuated position 46. The knob 67 is in the starting position 80. If the output element 51 in Drive direction 54 driven so hooks the pawl 44 into the receptacle 53 and thereby prevents further rotation of the receptacle 53. The output element 51 is locked. This is in Fig. 11 shown.

If the knob 67 from the starting position 81 in the in Fig. 12 shown operating position 80 adjusted so the damping spring 67 is tensioned. The pawl 44 is held by the retaining contour 59 in its actuated position 46 as long as the output element 51 is driven in the drive direction 54. At the pawl 44, the force of the damping spring 68 acts, as the arrow 69 shows. Once the output element 51 is no longer loaded in the drive direction 54, the pawl 44, the output element 51 to the retaining contour 59 in the in Fig. 13 Turning the direction of rotation 64 shown rotate until the pawl 44 is released and due to the force of the damping spring 68 in the in Fig. 13 shown unconfirmed position 47.

If the knob 67 from the in Fig. 13 shown operating position 81 in the in Fig. 10 shown start position 80 is rotated, the pawl 44 is in the direction of the in Fig. 10 shown actuated position 46 pivoted. Rotates in this pivoting movement, the output element 51 in the drive direction 54, so beat over the clutch drum 14 protruding ends of the holding plate 52 against the pawl 44 (FIG. Fig. 8, 9 ). These shocks are mitigated by the damping spring 68. Is a holding plate as in Fig. 13 dashed lines shown in the pivoting path of the pawl 44, the knob 67 can still be adjusted to its starting position 80. In this case, the damping spring 68 is tensioned. If the output element 51 moves about the axis of rotation 41, the pawl 44 can pivot into its actuated position 46 due to the force of the spring 68. As a result, in each rotational position of the output element 51, the adjustment of the starting device 39 into the starting position 42 is possible.

In the FIGS. 14 to 17 an embodiment is shown in which both a damping spring 68 and a return spring 55 are provided. On the arm 75 of the knob 67, a first actuator 76 is fixed, which in the in Fig. 14 shown starting position 80 of the knob 67 rests against a second actuating element 77. The first actuator 76 and the second actuator 77 are only adjacent to each other, so that between the actuators 76 and 77 only compressive forces but no tensile forces can be transmitted. The second actuating element 77 acts via the damping spring 68 on the pawl 44, which in Fig. 14 is arranged in its actuated position 46. Between the second actuating element 77 and the housing 2 or an element connected to the housing 2, the return spring 55 acts.

Fig. 15 shows the arrangement for a rotation of the output element 51 in the drive direction 54. In this position, the pawl 44 abuts the receptacle 53 on the output element 51, thereby blocking further rotation of the output element 51. The fact that two receptacles 53 are arranged opposite each other, can the output member 51 in the actuated position 46 of the pawl 44 to turn at most almost 180 ° until the pawl 44 comes into contact with a receptacle 53 and thereby blocks the output member 51. If the knob 67 from the in Fig. 15 Starting position shown 80 in the in Fig. 16 shown operating position 81 is set, the first actuator 76 is reset. The second actuator 77 may follow the movement of the first actuator 76 or may perform less or no travel. This is dependent on the design of the return spring 55 and the damping spring 68. The pawl 44 is in its actuated position 46, since it is fixed by the retaining contour 59, as long as the output element 51 is driven in the drive direction 54. Once the output element 51 is no longer driven in the drive direction 54, the pawl 44 is due to the force of the springs 68 and 55 in the in Fig. 17 shown unactuated position 47 back. In this case, the drive element 51 is rotated in an opposite direction 64 until the pawl 44 is released.

In the in the FIGS. 14 to 17 embodiment shown, the starting device 39 can be reset regardless of the position of the pawl 44 from the starting position 80 in the operating position 81. Due to the decoupling of the two actuators 76 and 77, the damping spring 68 exerts even when the pawl 44 is in its actuated position 46, no force on the knob 67 from. As a result, the release of the starting position 42 of the starting device 39 by the blocking device 43 is not with special needs. The blocking device 43 comprises the receptacle 53, the pawl 44 and the actuating elements 76, 77, 57 and springs 55, 68 arranged in operative connection between the pawl 44 and the mode selector 10 or the rotary knob 67.

Claims (15)

1. Working implement with an internal combustion engine (11) driving at least one tool of the working implement via a clutch (13), wherein the clutch (13) has at least one drive element (63) in operative connection with the internal combustion engine (11) and at least one output element (51) in operative connection with the tool, and wherein the working implement has a starting device (39) having a starting position (42) and an operating position (35) for the internal combustion engine (11),
   characterised in that the working implement has a blocking device (43) with a detent (44), which in an actuated position (46) projects into the movement path (71) of the output element (51) and limits the rotation of the output element (51) to less than one revolution, and which in a non-actuated position (47) enables the output element (51), and in that the starting device (39) has an actuating device (45) for the blocking device (43), which holds the detent (44) in the actuated position (46) in the starting position (42) of the starting device (39).
2. Working implement according to claim 1,
   characterised in that the blocking device (43) is moved into the actuated position (46) if the starting position (42) is engaged.
3. Working implement according to claim 1 or 2,
   characterised in that the detent (44) is mounted pivotably.
4. Working implement according to any of claims 1 to 3,
   characterised in that the detent (44) is spring-loaded by a return spring (55) towards the non-actuated position (47) of the blocking device (43), and in that the starting device (39) moves the detent (44) into the actuated position (46) against the force of the return spring (55).
5. Working implement according to any of claims 1 to 4,
   characterised in that a damping spring (68) is located in operative connection between the actuating device (45) and the detent (44).
6. Working implement according to any of claims 1 to 5,
   characterised in that the actuating device (45) has a starting position (80) assigned to the starting position (42) of the starting device (39) and an operating position (81) assigned to the operating position (35) of the starting device, and in that the actuating device (45) can be moved into the operating position (81) independently of the position of the detent (44).
7. Working implement according to any of claims 1 to 6,
   characterised in that the blocking device (43) has a holding contour (59), which holds the detent (44) in the actuated position (46) independently of the position of the starting device (39) if the output element (51) is loaded in the drive direction (54).
8. Working implement according to any of claims 1 to 7,
   characterised in that the detent (44) acts together with a receptacle (53) of the output element (51) when blocking the output element (51).
9. Working implement according to claim 8,
   characterised in that the output element (51) has a plurality of receptacles (53) arranged rotationally symmetrically to the axis of rotation (41) of the output element (51).
10. Working implement according to claim 8 or 9,
    characterised in that the blocking device (43) blocks an engagement of the starting position (42) if the output element (51) rotates.
11. Working implement according to any of claims 8 to 10,
    characterised in that the blocking device (43) has a locking contour (60, 62), which is non-rotatably connected to the output element (51) and which, if the output element (51) rotates and the detent (44) is moved from the non-actuated position (47) towards its actuated position (46), applies above a constructively predetermined speed a force to the detent (44) towards its non-actuated position (47).
12. Working implement according to claim 11,
    characterised in that the locking contour (60) adjoins the receptacle (53) on that side of the receptacle (53) which is on the outside with reference to the axis of rotation (41) and at the rear in the drive direction (54).
13. Working implement according to claim 11,
    characterised in that the locking contour (62) is formed at a flyweight (61), which is held at the output element (51) and at least partially covers the receptacle (53) at speeds above the constructively predetermined speed.
14. Working implement according to any of claims 1 to 13,
    characterised in that the starting position (42) of the starting device (39) is released by operating a throttle lever (8) of the working implement.
15. Working implement according to any of claims 1 to 14,
    characterised in that the clutch (13) comprises a centrifugal clutch and the output element (51) comprises a clutch drum (14).

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