EP2746556A1 - Carburetor for a hand-held work device and hand-held work device - Google Patents

Abstract

The carburetor (36) has a carburetor housing (40), in which a carburetor roller (37) is pivot-mounted around a rotational axis (76). A needle (48) is fixed on the carburetor roller, where the needle is protruded in a fuel opening (90) of the carburetor. The carburetor has a holding contour (19), which is connected rotationally with the carburetor roller. A distance of the holding contour amounts less than the 10 millimeter to the rotational axis at any point of the holding contour. An independent claim is included for a hand-held working tool with a housing.

Description

The invention relates to a carburetor for a hand-held implement and a hand-held implement.

From the JP 2004-068772 A a carburetor for a hand-held implement is known in which the position of the carburetor needle in a fuel port is adjustable via an adjusting screw. The adjusting screw is arranged in a recess and surrounded by a peripheral wall.

It is known that the distance between the peripheral wall and the adjusting element is so small that the adjusting element can only be adjusted with a special tool provided for the adjustment. The adjustment should be made especially in the manufacture of the implement and in the service. This avoids incorrect positioning by the user.

The position of the needle relative to the carburetor is set in the manufacture of the implement according to geometric considerations. The actual position of the needle relative to the carburetor is dependent on the manufacturing tolerances, so that the amount of fuel supplied to the internal combustion engine during operation may vary from carburetor to carburetor depending on the tolerance position. In order to ensure good running behavior of the internal combustion engine for all possible tolerance combinations, the carburettor must be set comparatively fat.

The invention has for its object to provide a hand-held implement, which has a good running behavior and low exhaust emissions. Another object of the invention is to provide a carburetor for a hand-held implement, which allows a good running behavior of an internal combustion engine with low fuel consumption.

This object is achieved with respect to the carburetor by a carburetor having the features of claim 1. With regard to the hand-held implement, the object is achieved by a hand-held implement with the features of claim 14.

The retaining contour makes it possible to fix the rotatably mounted carburetor and to move the adjustment relative to the retaining contour. By fixing the carburetor roller adjustment of the position of the needle relative to the carburetor is possible without the carburetor can rotate. The fixation of the retaining contour can be done via a simple design additional tool. The fact that the carburetor can be fixed in a simple manner on the retaining contour for adjusting the adjustment, a setting of the needle during operation, ie when the engine is running is possible. This allows a particularly accurate adjustment can be achieved. The setting can be done manually or automatically. About the holding contour, the carburetor can be kept to adjust the needle advantageous in the idle position of the carburetor. About the retaining contour, however, it is also possible to set predetermined rotational positions of the carburetor and set for these rotational positions, the position of the needle relative to the carburetor. This allows a particularly accurate setting. Due to the exact setting, low exhaust gas values of the internal combustion engine can be achieved. Manufacturing tolerances, which can not be taken into account in a purely geometric adjustment of the position of the needle in the fuel port, can be compensated in the adjustment of the position of the needle in the operation of the internal combustion engine, which is made possible by the holding contour.

The setting of the carburetor is advantageous when the carburetor is mounted in the hand-held implement. The retaining contour must therefore from the outside, so by a housing of the implement, be accessible. For hand-held implement, which are often exposed to contamination in operation, a largely closed outer shell of the housing is desirable. In order to still allow adjustment of the carburetor during operation, it is provided that the holding contour is arranged close to the axis of rotation of the carburetor. The distance between the holding contour and the axis of rotation is less than approximately 10 mm at each point of the holding contour. A housing opening, through which the retaining contour is accessible, can thereby be made comparatively small. The distance is measured in a plane perpendicular to the axis of rotation of the carburetor. The needle must be so arranged in operation due to the rotational movement of the carburetor roller that the longitudinal axis of the needle coincides with the axis of rotation of the carburetor roller. As a result, holding contour and setting contour can be arranged so that they are accessible through a common housing opening. Advantageously, the distance of the retaining contour to the axis of rotation at each point of the retaining contour is less than about 8 mm.

The holding contour is arranged in particular concentric to the axis of rotation of the carburetor. Advantageously, the engagement contour is arranged in a recess which is bounded by a peripheral wall. The peripheral wall limits access to the engagement contour and prevents a tool not provided for adjustment of the needle from being engaged with the engagement contour.

Advantageously, the retaining contour is arranged on the peripheral wall. As a result, no additional space is required for the retaining contour. The holding contour is arranged in particular on the front side of the peripheral wall. A tool for fixing the retaining contour can easily engage the retaining contour, which is arranged on the front side of the peripheral wall. A tool for fixing the retaining contour may be formed as a sleeve around the tool for adjusting the setting contour. This results in a compact, simple construction.

A simple design results when the holding contour is formed directly on the peripheral wall. The retaining contour is advantageously formed by depressions in the peripheral wall extending from the end face of the peripheral wall in the peripheral wall extend. To form the retaining contour thereby no additional components are needed. The peripheral wall is advantageously made of plastic, so that the holding contour can be produced in a plastic injection molding process together with the peripheral wall. For the production of the retaining contour thereby no additional manufacturing steps are required.

The outer circumference of the peripheral wall is advantageously comparatively small, resulting in a compact construction. The outer diameter of the peripheral wall is advantageously less than about 15 mm at the retaining contour. In particular, the outer diameter of the peripheral wall on the retaining contour is less than about 12 mm. The outer diameter of the peripheral wall is advantageously at most 2.5 times as large as the diameter of the engagement contour. The outer diameter of the peripheral wall is measured on the retaining contour and denotes the largest outer diameter of the peripheral wall on the retaining contour.

Advantageously, the peripheral wall has an annular cross-section. The peripheral wall is advantageously arranged concentrically to the axis of rotation of the carburetor. The peripheral wall advantageously encloses the engagement contour so closely that only a specially provided tool can engage the engagement contour. The distance between the peripheral wall and the engagement contour advantageously corresponds at most to half the diameter of the engagement contour. The diameter of the engagement contour is the largest diameter for an irregularly shaped engagement contour. It can also be provided that the engagement contour is formed on the end face of the adjusting element. In this case, the peripheral wall can close the adjusting element closely and with a very small distance. The distance between the peripheral wall and the engagement contour is advantageously at most about 2.5 mm. For the adjustment of the engagement contour, a special tool is advantageously provided. In particular, in order to avoid engagement of another tool on the engagement contour, the distance between the peripheral wall and the engagement contour is at most about 1.5 mm. Preferably, the distance between the peripheral wall and the engagement contour is about 0.8 mm to about 1.2 mm.

The holding contour advantageously has at least one tooth. In particular, a plurality of teeth are arranged distributed uniformly on the end face of the peripheral wall. Be particularly advantageous four teeth have been found. However, a different number of teeth may be advantageous. The holding contour advantageously has at least one first flank which, in side view, encloses an angle of less than approximately 10 °, in particular less than 5 °, with the axis of rotation of the carburetor roll. The first flank is in particular aligned approximately parallel to the axis of rotation of the carburetor roll. Characterized in that the first edge of the retaining contour is aligned at a low angle or approximately parallel to the axis of rotation of the carburetor, the holding forces can be transmitted particularly well. The first flank is advantageously opposite to the direction of rotation of the carburetor from an idle position to a full throttle position. Upon rotation of the carburetor in the direction of rotation from the idle position to the full throttle position, the first edge is the leading edge. As a result, the carburetor can be fixed well in the idle position, so that in particular an adjustment of the position of the needle during idling is easily possible. Advantageously, the retaining contour has at least one inclined to the axis of rotation of the carburetor second edge. The second flank advantageously includes an angle with the axis of rotation of the carburetor roll which is from about 20 ° to about 70 °. The angle between the second flank and the axis of rotation is in particular about 30 ° to about 60 °. Due to its inclination to the axis of rotation of the carburetor, the second edge allows easy engagement of a holding tool in the holding contour and an automatic centering between the flanks. As a result, an automated adjustment of the adjustment is simplified. The first and second flanks are advantageously formed on the at least one tooth.

The engagement contour is expediently a special contour that can be adjusted using a special tool. This will ensure that carburetor adjustment can only be made while the implement is being manufactured or serviced. An improper setting of the carburetor is thereby avoided.

For a hand-held implement with a housing in which a carburetor for supplying fuel and combustion air for an internal combustion engine is arranged, wherein the carburetor has a carburetor housing in which a carburetor roll is rotatably mounted about an axis of rotation, wherein on the carburetor roller a needle is defined, which projects into a fuel port of the carburetor, wherein the position of the needle is adjustable relative to the carburetor via an adjustment, wherein the adjusting element has an engagement contour on which a tool can engage for adjusting the adjusting element, it is provided that the carburetor has a holding contour which is rotatably connected to the carburetor, and that the distance of the holding contour to the axis of rotation at each point of the holding contour less than is about 10 mm, in particular less than 8 mm.

Advantageously, the housing of the implement has a housing opening through which the retaining contour is accessible. As a result, an adjustment of the adjusting element with the internal combustion engine running, that is, during operation, is readily possible. To avoid contamination of the housing interior and damage to the housing in an impact, the housing opening should be kept as small as possible. Between the holding contour and the housing opening, a slot is advantageously formed. The largest, measured in a plane perpendicular to the axis of rotation width of the slot is advantageously less than about 7 mm, in particular less than about 4 mm. The largest width of the slot is advantageously smaller than the diameter of the engagement contour. Advantageously, the retaining contour is formed on the end face of the peripheral wall, so that only a very small space for the retaining contour and thus only a very small housing opening for engagement of a tool on the retaining contour is needed. The slot is advantageously designed so that a round rod with a diameter of 7 mm can not be inserted into the slot. This can be avoided that in operation branches or the like can engage through the slot in the housing and cause damage.

The implement advantageously has a starting device with which the internal combustion engine can be started. The starting device is advantageously used to adjust the carburetor in a starting position. A simple construction results when a detent contour, which is part of a starting device, is arranged on the outside of the peripheral wall facing away from the recess. In addition, one or more reinforcing struts may be provided on the peripheral wall. Because these elements are located outside the perimeter wall are, they are not suitable for fixing the carburetor roller for adjusting the adjustment because they are not accessible through the housing opening from the outside and so a setting during operation is not possible.

Fig. 1

eine schematische, perspektivische Darstellung eines Arbeitsgeräts,

Fig. 2

das Gehäuse des Arbeitsgeräts in perspektivischer Darstellung,

Fig. 3

eine schematische Schnittdarstellung durch den Verbrennungsmotor des Arbeitsgeräts,

Fig. 4

eine schematische Schnittdarstellung durch den Vergaser des Arbeitsgeräts,

Fig. 5

eine Seitenansicht eines Werkzeugs zur Einstellung des Einstellelements des Vergasers,

Fig. 6

eine Draufsicht auf den Vergaser,

Fig. 7

eine vergrößerte Darstellung der Draufsicht auf die Vergaserwalze aus Fig. 6,

Fig. 8

eine vergrößerte Darstellung des Bereichs der Haltekontur des Vergasers aus Fig. 4.

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

Fig. 1

a schematic, perspective view of a working device,

Fig. 2

the housing of the implement in perspective view,

Fig. 3

a schematic sectional view through the engine of the working device,

Fig. 4

a schematic sectional view through the carburetor of the working device,

Fig. 5

a side view of a tool for adjusting the setting element of the carburetor,

Fig. 6

a top view of the carburetor,

Fig. 7

an enlarged view of the top view of the carburetor from Fig. 6 .

Fig. 8

an enlarged view of the area of the retaining contour of the carburetor Fig. 4 ,

Fig. 1 shows a hand-held implement 1, namely a brushcutter. However, the implement 1 may be another hand-held implement such as a power saw, a power cutter, a hedge trimmer, a blower, a harvester such as an olive shaker or the like. Is the implement a blower or suction device, so the driven by the drive motor tool is the fan, which promotes the working air flow.

The implement 1 has a housing 2, from which a Anwerfgriff 3 for starting a arranged in the housing 2, in Fig. 1 schematically shown internal combustion engine 20 protrudes. The housing 2 is connected via a guide tube 4 with a gear head 9. Through the guide tube 4 protrudes a drive shaft, not shown, which drives a tool 10 about a rotation axis 11 via a gear arranged in the transmission 9 gear. The tool 10 is a knife in the embodiment. However, the tool 10 may also be a thread mowing head or the like. Adjacent to the gear head 9, a protection 12 is fixed to the guide tube.

To guide the implement 1, a handle link 5 is attached to the guide tube 4, which carries two handles 6. On one of the handles 6, a throttle 7 and a throttle lever lock 8 are mounted. The throttle lever 7 serves to operate the internal combustion engine.

As Fig. 2 shows, the housing 2 has a plurality of cooling air openings 13. The cooling air openings 13 serve for the entry or exit of cooling air. The housing 2 has an air filter cover 16, under which a in Fig. 3 is schematically shown air filter 35 is arranged. The air filter cover 16 forms part of the housing 2. From the housing 2 protrudes a Purgerbalg 14, which serves to promote fuel in the fuel system of a carburetor of the working device 1. For fixing the housing 2 on the guide tube 4, a mounting clamp 17 is provided. The implement 1 also has a fuel tank 15.

As Fig. 2 shows, a housing opening 18 is formed in the housing 2 adjacent to the air filter cover 16. About the housing opening 18 a directly below the housing opening 18 arranged retaining contour 19 is accessible.

Fig. 3 schematically shows the engine 20 of the working device 1. The internal combustion engine 20 is advantageously a two-stroke engine, in particular a single-cylinder engine.

The internal combustion engine 20 has a cylinder 21, in which a combustion chamber 22 is formed. The combustion chamber 22 is delimited by a piston 24 reciprocating in the cylinder 21. The piston 24 drives via a connecting rod 25 a rotatably mounted in a crankcase 23 crankshaft 26 to rotate. From the combustion chamber 22 leads an outlet 34. On the cylinder 21 opens a mixture channel 28 with a mixture inlet 30 into the crankcase and an air channel 27 with at least one air inlet 29. The air inlet 29 is at least one formed on the piston piston piston pocket 31 31 with one or more overflow windows 33 is connected by one or more transfer passages 32 when the piston 24 is in the region of its top dead center. The overflow channels 32 connect the interior of the crankcase 23 in the region of bottom dead center of the piston 24 with the combustion chamber 22. The air channel 27 and the mixture channel 28 are separated by a partition wall 38 over at least part of their length. The air channel 27 and the mixture channel 28 are partially formed in a carburetor 36 and open at the clean room of an air filter 35. The air filter 35 is held between the air filter cover 16 and an air filter bottom 77. In the exemplary embodiment, the air filter 35 is shown as a flat filter. However, a wide variety of designs of the air filter 35 are possible. The air filter 35 is advantageously fixed by the air filter cover 16.

The carburetor 36 is designed as a roller carburetor and has a carburetor roller 37 which is rotatably mounted about an axis of rotation 76. As it rotates, the carburetor roller 37 is moved axially in the direction of the axis of rotation 76. For this purpose, a cam contour 79 is provided, which in Fig. 3 is shown schematically. In Fig. 3 the carburetor roller 37 is shown in its full throttle position 89, in which the carburetor roller 37, the flow cross sections in the air duct 27 and the mixture channel 28 largely, in particular completely releases.

In operation, fuel / air mixture flows in a flow direction 39 through the mixture passage 28 and via the mixture inlet 30 into the crankcase 23 when the piston 24 is in the region of its top dead center. During the downward stroke of the piston 24, the fuel / air mixture is compressed in the crankcase 23 and flows in the region of the bottom dead center of the piston 24 into the combustion chamber 22, where it again after Compression is ignited in the subsequent upward stroke of the piston 24. The combustion accelerates the piston 24 back toward its bottom dead center. As soon as the piston 24 opens the outlet 34, the exhaust gases flow out of the combustion chamber 22.

When the piston 24 is in the region of top dead center, fuel-lean or fuel-free air is pre-stored in the overflow channels 32 via the air channel 27. This air flows in the region of the bottom dead center of the piston 24 into the combustion chamber 22 and flushes the exhaust gases through the outlet 34 before fresh fuel / air mixture flows from the interior of the crankcase 23 via the overflow channels 32 into the combustion chamber 22.

Fig. 4 shows the structure of the carburetor 36 in detail. The carburetor 36 has a carburetor housing 40, in which the carburetor roller 37 is rotatably mounted about the axis of rotation 76. To the side from which the carburetor roller 37 is inserted into the carburetor housing 40, the carburetor housing 20 is closed by a cover 41. Concentric with the axis of rotation 76, a fuel channel 44 projects into the carburetor cylinder 37. The fuel channel 44 is guided in a fuel pipe 45 in the exemplary embodiment. At the end of the fuel channel 44, a fuel opening 90 is formed, which opens into the mixture channel 28. The fuel channel 44 is of an in Fig. 4 schematically drawn, trained in the usual way control chamber 43 fed. The control chamber 43 is separated by a control membrane 92 from a compensation chamber 42. The carburetor 36 is therefore designed as a diaphragm carburetor. In the exemplary embodiment, the control chamber 43 is arranged on the side facing away from the mixture channel 28 of the carburetor 36. The fuel pipe 45 extends through the air channel 27. The fuel opening 90 is arranged in the region of a partition wall section 46. The partition wall section 26 is part of the partition wall 38 (FIG. Fig. 3 ), the air channel 27 and mixture channel 28 separates, and formed on the carburetor roller 37.

From the side of the carburetor 36 opposite the fuel passage 44 and the control chamber 43, a needle 48 protrudes into the fuel opening 90. The depth that the needle 48 dips into the fuel pipe 45 may be fed through the fuel opening 90 Fuel quantity to be adjusted. As Fig. 4 shows the fuel pipe 45 and the needle 48 protrude from opposite sides in an opening 47 of the partition wall portion 46 a. It can also be provided that the fuel pipe 45 projects through the partition wall section 46 at an opening 47.

The carburetor roller 37 is longitudinally displaceable by a predetermined path in the direction of the axis of rotation 76. Upon axial displacement of the carburetor roller 37 due to a rotational movement from the idle position 88 for full throttle position 89, the needle 48 moves from the fuel pipe 45 and thereby increases the mixture channel 28 supplied amount of fuel. The carburetor roller 37 is spring biased by a spring 61 which biases the carburetor roller 37 in the direction in which the needle 48 farthest into the fuel pipe 45.

In Fig. 4 the carburetor roller 37 is shown in its idle position 88, in which the needle 48 farthest into the fuel pipe 45 dips. Only a small flow cross-section is released, since the sections of mixture channel 28 and air channel 27 formed in the carburetor roller 37 extend transversely to the flow direction 39 (FIG. Fig. 3 ) are arranged. Fig. 3 shows the carburetor 37 in full throttle position 89, in which the carburetor 37 formed in the sections of air duct 27 and the mixture channel 28 are aligned in the flow direction 39, so that the maximum free flow cross-sections result.

To start the internal combustion engine 20, a starting device is provided which comprises an actuating knob 58. The operating knob 58 is rotatably mounted in a guide 59 and slidably mounted in its longitudinal direction. The displacement in the longitudinal direction is possible only in a constructively predetermined position. Both in the direction of rotation and in the axial direction of the actuating button 58 is spring-loaded by a spring 60, which biases the operating knob 58 in the direction of its unactuated position. The operation knob 58 has a in the Fig. 4 and 6 shown hook 68 which forms a latching element and locked with a rotatably connected to the carburetor roller 37 hooks 63 in a start position.

As Fig. 4 shows, the hook 63 is formed on a non-rotatably connected to the carburetor roller 37 actuator 62. The actuator 62 and the carburetor roller 37 are disposed on opposite sides of the carburetor 36 on the lid 41. The actuator 62 is fixed, so immovably connected to the carburetor roller 37 both in the direction of rotation about the axis of rotation 76 and in the longitudinal direction of the axis of rotation 76.

In order to adjust the position of the needle 48 in the fuel passage 45 and thus the amount of fuel supplied into the mixture channel 48, the position of the needle 48 in the longitudinal direction of the rotation axis 76 relative to the carburetor roller 37 is adjustable. For this purpose, an adjustment member 49 is provided, which is formed in the embodiment as fixed to the needle 48, screwed into a thread 50 screw. The thread 50 is formed on the carburetor roll 37 or a member fixedly connected to the carburetor roll 37. The adjusting member 49 has a head 51, on the outer circumference of an engagement contour 52 is formed. The engagement contour 52 is a non-standard, adjustable only with a special tool special contour. In the exemplary embodiment, the engagement contour 52 is formed as a rounded hexagon. However, it can be provided any other engagement contours, for example, rounded outer contours or provided on the front side engagement contours such as a specially designed slot or Phillips. By screwing or unscrewing the adjustment member 49 in the thread 50, so by turning the adjustment member 49 relative to the carburetor 37, the immersion depth of the needle 48 is set in the fuel passage 45.

The engagement contour 52 is surrounded by a peripheral wall 54. This ensures that the adjustment element 49 can only be adjusted with a special tool provided for this purpose, which can be inserted into the peripheral wall 54. The peripheral wall 54 is arranged concentrically about the axis of rotation 76 and has an annular cross-section in the exemplary embodiment. The peripheral wall 54 extends approximately cylindrically with walls inclined slightly in the longitudinal direction of the axis of rotation 76, in order to enable demolding when producing the peripheral wall 54 in an injection molding process. To adjust the position of the needle 48 relative to the carburetor 37 also while the internal combustion engine 20 to allow through the housing 2 of the implement, which is also in Fig. 2 shown holding contour 19 which is accessible from the outside of the housing 2. The holding contour 19 is formed on an end face 55 of the peripheral wall 54 and comprises a plurality of teeth 56 in the exemplary embodiment. The hook 63 is arranged on an outer side 91 of the peripheral wall 54 arranged externally with respect to the axis of rotation 76. The peripheral wall 54 defines a recess 53 which is cylindrical and at the bottom of the head 51 of the adjusting member 49 is arranged.

As the Fig. 4 and 6 show, a holder 57 for the outer shell of a Bowden cable is arranged on the cover 41. In the exemplary embodiment, the holder 57 is arranged on the side opposite the actuating knob 58 side of the carburetor 36.

Fig. 5 shows a special tool 80 for adjusting the position of the needle 48. The special tool 80 has a handle 87 which is connected in a conventional manner via a shaft 93 with an engagement portion 81. The engagement portion 81 is approximately cylindrical in the embodiment and has on its inside a special contour, not shown, which corresponds to the engagement contour 52 of the head 51 and can engage in this. The special contour is not a standardized contour but a contour specially matched to the engagement contour 52. On the shaft 93, a holding device 82 is pushed. The holding device 82 is advantageously pushed loosely over the shaft 93. However, the holding device 82 can also be fixed in the axial direction and rotatable on the shaft 93. The holding device 82 has a holding section 86, on which an operator or a setting machine can fix the holding device 82. At its end face, the handle 87 and the holding portions 86 facing away from the end of the holding device 82 has a mating contour 83 which can engage in the retaining contour 19. The mating contour 83 has flanks 84 and 85, which will be described in more detail below. On the holding device 82, a setting portion 96 is arranged, which is advantageously clamped on the holding device 82 and carries a scale. The handle 87 has a sighting portion 97. When the mating contour 83 and the engaging portion 81 are engaged with the engagement contour 52 and the retaining contour 19, the aiming portion 97 coincides is brought to the setting portion 96 with the zero of the scale. This is done by adjusting the adjusting portion 96 relative to the holding device 82 by overcoming the clamping force. In adjusting the position of the needle 48, both the holding portion 86 and the setting portion 96 are held by the operator. The angle at which the engagement portion 81 is rotated with respect to the engagement contour 52 can be read on the scale via the aiming portion 97.

In Fig. 6 For example, the carburetor 36 is shown in idle position 88. In this position, the actuator 62 abuts an idle stop 73. The idling stop 73 is advantageously formed on an adjusting element 74, for example a screw. Thereby, the rotational position of the carburetor roller 37 and thus also the position in the longitudinal direction of the axis of rotation 76 can be adjusted in idle position 88. For accelerating a Bowdenzugaufnahme 67 is provided on the actuating element 62, in which the Bowden cable of a Bowden cable, not shown, can be inserted. The sheath of the Bowden cable is fixed in the holder 57. When pulling on the Bowden cable, the actuating element 62 and thus also the carburetor roller 37 are moved in a direction of rotation 72. From the spring 61 ( Fig. 4 ), the carburetor roller 37 is biased toward the idle position 88. The Bowden cable is advantageous over the throttle 7 ( Fig. 1 ). Adjacent to the holder 57, a full-gas stop 75 is formed on the lid 41, against which the actuating element 62 strikes in full-throttle position 89.

To insert a starting position, the operating knob 58 is rotated from the outside of the housing 2 seen in the counterclockwise direction and then in the direction of arrow 94 in Fig. 6 pressed into the guide 59. As Fig. 6 Also shows, the operating knob 58 has lugs 66, parallel to the arrow 94, ie in the direction in which the operating knob 58 must be pressed into the guide 59 run. The guide 59 has slots 65, in which the lugs 66 can engage in the provided for pressing the operating knob 58 rotational position of the operating knob 58. As Fig. 6 shows, the operating knob 58 can not be pressed in the unactuated position in the direction of arrow 94, since the tabs 66 abut in the illustrated rotational position on the front side of the guide 59. First, the operating knob 58 must be slightly less than 90 ° be rotated counterclockwise until the lugs 66 are in register with the slots 65. Subsequently, the operation knob 58 can be moved in the direction of the arrow 94. Both the rotational movement of the actuating button 58 and the movement in the direction of the arrow 94 in the guide 59 takes place against the force of the spring 60th

In the pressed-in position in the guide 59 hooks the hook 68 of the operating knob 58 with the hook 63 on the actuating element 62. As a result, a start position is set. On the operating knob 58 may be provided a contour which raises the carburetor roller 37 in the starting position to increase the amount of fuel supplied for the start. The carburetor roller 37 is advantageously adjusted relative to its idle position 88 slightly in the direction of the full throttle position 89, ie in the direction of rotation 72, so that the intake air quantity is increased relative to the idle position 88. To release the starting position, the operator gives gas, whereby the actuating element 62 is pivoted in the direction of rotation 72 and the hook 63 is disengaged from the hook 68. Instead of the hooks 63 and 68, other elements for setting a starting position, in particular for locking in a starting position can be provided.

Fig. 6 dashed line shows the contour of the housing opening 18. Like Fig. 6 shows, between the housing opening 18 and the peripheral wall 54, only a narrow slot 78 is formed. The slot 78 has on the air filter cover 16 remote area an annular shape and is limited to the air filter cover 16 side facing the straight air filter cover 16 and the circular peripheral wall 54, so that the width of the slot 78 is not constant in this area. The slot 78 has a maximum width f, which is measured in the embodiment of the air filter cover 16. The width f is less than about 7 mm, in particular less than about 4 mm. In the exemplary embodiment, the width f is less than about 3 mm. The width e, f of the slot 78 is in each case measured perpendicular to the peripheral wall 54 and to the axis of rotation 76 radially outward. Because the slot 78 is narrow, it is not possible for the actuating element 62 to be arranged on the elements arranged on the outside 91 of the circumferential wall 54, namely the hook 63 and also on the outside 91 Reinforcing strut 64 to fix. For fixing the carburetor roller 37, therefore, the retaining contour 19 is provided on the end face 55 of the peripheral wall 54.

The FIGS. 7 and 8 show the structural design of the retaining contour 19 in detail. As the FIGS. 7 and 8 show, the retaining contour 19 has first flanks 69, which extend parallel to the axis of rotation 76 in the embodiment. The first flanks close with the rotation axis 76 in side view advantageously an angle which is at most about 10 °, in particular at most about 5 °. The first flanks 69 are opposite to the direction of rotation 72. The first flanks 69 are thus the advancing in a rotation of the carburetor cylinder 37 in the direction of rotation 72 flanks of the teeth 56. The retaining contour 19 also has second flanks 70 which are facing away from the direction of rotation 72. When rotated in the direction of rotation 72, the second flanks 70 are the trailing edges of the teeth 56. As in particular Fig. 8 shows, the second flanks 70 are formed obliquely. The second flanks 70 close in a sectional view through the axis of rotation 76, as shown in FIG Fig. 8 is shown with the axis of rotation 76 an angle α. The angle α is advantageously from about 20 ° to about 70 °, in particular from about 30 ° to about 60 °. However, other angles α can also be advantageous. Advantageously, the first flanks 69 have a smaller inclination to the axis of rotation 76 than the second flanks 70.

As the FIGS. 7 and 8 also show, the teeth 56 have on its side facing the recess 53 an insertion bevel 71, which facilitates the threading of the tool 80. The peripheral wall 54 has an in Fig. 7 shown outer diameter c. The outer diameter c is measured at the rotation axis 76 inclined course of the peripheral wall 54 on the retaining contour 19. The outer diameter c is less than about 20 mm, advantageously less than about 15 mm, in particular less than about 12 mm. In the exemplary embodiment, the outer diameter c is less than 11 mm. The retaining contour 19 has, relative to the axis of rotation 76, a distance g measured in a plane perpendicular to the axis of rotation 76. The distance g is constant in the embodiment due to the circular shape of the outer periphery and is less than about 10 mm, in particular less than about 8 mm. Advantageously, the distance g is less than about 6 mm. Is the distance of the retaining contour 19th to the axis of rotation 76 is not constant, the distance g is the largest distance of the retaining contour 19 to the axis of rotation 76th

The mating contour 83 of the holding device 82 (FIG. Fig. 5 ) has third flanks 84 which are parallel to a longitudinal direction 95 of the shaft 93. The longitudinal direction 95 is aligned congruent with the rotation of the counter contour 83 in the retaining contour 19 to the axis of rotation 76. When the retaining contour 83 engages in the retaining contour 19, the third flanks 84 rest against the first flanks 69. The mating contour 83 has fourth flanks 85, which are inclined in accordance with the second flanks 70 and abut against the second flanks 70 when the mating contour 83 engages in the retaining contour 19.

Fig. 8 also shows the dimensions of the arrangement in detail. The engagement contour 52 has a diameter a which is only slightly smaller than the inner diameter b of the peripheral wall 54. The inner diameter b is advantageously less than about 10 mm, in particular less than about 7 mm. The diameter a is the largest diameter of the retaining contour 52. The diameter a is advantageously less than about 8 mm, in particular less than about 6 mm. Particularly advantageously, the diameter a is less than about 5 mm. The distance d formed between the peripheral wall 54 and the engagement contour 52 is advantageously at most half as large as the diameter a of the engagement contour 52. The distance d is advantageously at most approximately 2.5 mm, in particular at most approximately 1.5 mm. In the exemplary embodiment, the distance d is about 1 mm. The width f is advantageously smaller than the diameter a of the engagement contour 52. The outer diameter c of the peripheral wall 54, which in FIG Fig. 7 is shown, advantageously also comparatively small, so that only a small housing opening 18 is required. The outer diameter c of the peripheral wall 54 on the retaining contour 19 is advantageously at most 2.5 times as large as the diameter a of the engagement contour 52. Fig. 8 schematically shows the arrangement of the housing opening 18. The slot 78 which is formed between the edge of the housing opening 18 and the peripheral wall 54 on the air filter cover 16 side facing away, has a width e, which is advantageously smaller than the diameter a of the engagement contour 52 , The width e is measured in a plane which is perpendicular to the axis of rotation 76. Advantageously, the width e is about half of the Diameter a of the engagement contour 52. The width e is advantageously less than about 4 mm, in particular less than about 3 mm. In order to avoid damage to the engagement contour 19 and to protect the engagement contour 19 from soiling, the engagement contour 19 can be arranged in a plane below the housing opening 18. The distance e is then measured in the projection of the housing opening 18 parallel to the axis of rotation 76 in the plane of the end face 55 of the peripheral wall 54.

To set the amount of fuel supplied, the internal combustion engine 20 is advantageously put into operation and the tool 8 is attached to the engagement contour 52 and the retaining contour 19. With the holding portions 86, the carburetor 37 is rotated to its idle position 88. In this position, the engagement contour 52 is adjusted by turning the handle 87 relative to the holding portions 86 until a desired idling adjustment is achieved. It may also be provided to provide the adjustment in one or more other positions of the carburetor roller 37. In order to fix the carburetor roller 37 in other rotational positions, other configurations of the engagement contour 19 and the counter contour 83 may be expedient. Due to the alignment of the first flanks 69 parallel to the axis of rotation 76, the design shown in the embodiment is particularly suitable for setting in idle position 88th

Claims (18)

Carburettor for a hand-held implement with a carburetor housing (40) in which a carburetor roller (37) is rotatably mounted about a rotation axis (76), wherein on the carburetor roller (37) a needle (48) is fixed, which in a fuel port (90 ) of the carburetor (36), wherein the position of the needle (48) relative to the carburetor roller (37) via an adjusting element (49) is adjustable, wherein the adjusting element (49) has an engagement contour (52) on which a tool for adjustment of the adjusting element (49) can attack,
characterized in that the carburetor (36) has a retaining contour (19) which is non-rotatably connected to the carburetor roller (37), and that the distance (g) of the retaining contour (19) to the axis of rotation (76) at each point of the retaining contour ( 19) is less than about 10 mm. Carburettor according to claim 1,
characterized in that the engagement contour (52) in a recess (53) is arranged, which is bounded by a peripheral wall (54). Carburettor according to claim 2,
characterized in that the retaining contour (19) on the peripheral wall (54) is arranged. Carburetor according to claim 3,
characterized in that the retaining contour (19) is arranged on the end face on the peripheral wall (54). Carburettor according to one of claims 2 to 4,
characterized in that the outer diameter (c) of the peripheral wall (54) on the retaining contour (19) is less than about 15 mm. Carburetor according to one of claims 2 to 5,
characterized in that on the recess (53) facing away from the outer side (91) of the peripheral wall (54), a latching element is arranged, which is part of a starting device. Carburettor according to one of claims 2 to 6,
characterized in that the peripheral wall (54) has an annular cross-section. Carburettor according to one of claims 2 to 7,
characterized in that the distance (d) between the peripheral wall (54) and the engagement contour (19) is at most about 2.5 mm. Carburettor according to one of claims 1 to 8,
characterized in that the retaining contour (19) has at least one tooth (56). Carburettor according to one of claims 1 to 9,
characterized in that the retaining contour (19) has at least one first flank (69) which forms an angle of less than about 10 ° with the axis of rotation (76) of the carburetor roll (37). Carburetor according to claim 10,
characterized in that the first flank (69) of a rotational direction (72) of the carburetor roller (37) from an idle position (88) to a full throttle position (89) is opposite. Carburettor according to one of claims 1 to 11,
characterized in that the retaining contour (19) has at least one second flank (70) which forms an angle (α) of about 20 ° to about 70 ° with the axis of rotation (76) of the carburetor roller (37). Carburetor according to one of claims 1 to 12,
characterized in that the engagement contour (52) is a special tool (80) adjustable special contour. A handheld work tool having a housing (2) in which is disposed a carburetor (36) for supplying fuel and combustion air to an internal combustion engine (20), the carburetor (36) having a carburetor housing (40) in which a carburetor drum (37) is provided ) is rotatably mounted about an axis of rotation (76), wherein on the carburetor roller (37) a needle (48) is fixed, which projects into a fuel port (90) of the carburetor (36), wherein the position of the needle (48) relative to Carburettor roller (37) via an adjusting element (49) is adjustable, wherein the adjusting element (49) has an engagement contour (52) on which a tool (80) for adjusting the adjusting element (49) can engage, characterized in that the carburetor ( 36) has a retaining contour (19) which is non-rotatably connected to the carburetor roll (37) and that the distance (g) of the retaining contour (19) to the axis of rotation (76) at each point of the retaining contour (19) less than about 10 mm. Working device according to claim 14,
characterized in that the housing (2) has a housing opening (18) through which the retaining contour (19) is accessible, wherein between the retaining contour (19) and the housing opening (18) has a slot (78) is formed. Tool according to claim 14 or 15,
characterized in that the maximum width (f) of the slot (78) is less than about 7 mm, the width (f) of the slot (78) being measured in a plane perpendicular to the axis of rotation (76) of the carburetor roller (37). Tool according to one of claims 14 to 16,
characterized in that the maximum width (f) of the slot (78) is smaller than the diameter (a) of the engagement contour (52), wherein the width (f) of the slot (78) in a plane perpendicular to the axis of rotation (76) of Carburetor roller (37) is measured. Tool according to one of claims 14 to 17,
characterized in that the slot (78) is designed so that a round rod with a diameter of 7 mm can not be inserted into the slot (78).

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