EP3489481A1 - Manually operated work device - Google Patents

Abstract

A hand-held implement (1) has an internal combustion engine (9) and a fan (22) for conveying cooling air for the internal combustion engine (9). The internal combustion engine (9) has a cylinder (13) and a crankcase (14). The fan (22) is arranged in a Lüfterradgehäuse (23) and is driven by the internal combustion engine (9) in operation in a rotational direction (24) rotating. The Lüfterradgehäuse (23) has a the crankcase (14) of the internal combustion engine (9) facing the rear wall (25) and a peripheral boundary (26). The peripheral boundary (26) has a first end (27) and a second end (28, 28 ') defining an exit opening (29) for cooling air to be delivered to the cylinder (13). The outlet opening (29) extends in the direction of rotation (24) from the second end (28, 28 ') to the first end (27). In the Lüfterradgehäuse (23) an additional passage opening (30, 64, 66) is provided, flows through the cooling air from the Lüfterradgehäuse (23) to the outside of the crankcase (14). An advantageous embodiment results when the angular distance (a) measured in the direction of rotation (24) from the first end (27) between the first end (27) and the passage opening (30, 64, 66) is smaller than that in the direction of rotation ( 24) based on the passage opening (30, 64, 66) measured angular distance (β) between the passage opening (30, 64, 66) and the second end (28, 28 '), wherein the angular distance (a, β) each as a circumferential angle is measured about the axis of rotation (18).

Description

The invention relates to a hand-held implement with an internal combustion engine of the type specified in the preamble of claim 1.

From the EP 2 607 642 A1 is a hand-held implement with an internal combustion engine and a fan for promoting cooling air for the internal combustion engine known. The fan is arranged in a fan housing. The internal combustion engine has an injection valve for supplying fuel. The injection valve is arranged in a cooling region into which cooling air conveyed by the fan wheel flows via a connection opening in the rear wall of the fan wheel housing.

Fan wheel housing are usually formed approximately helically, wherein the distance of the peripheral wall of the fan wheel housing to the axis of rotation of the fan in the direction of rotation of the fan increases. At the end of the fan coil usually an outlet opening is provided, flows through the cooling air from the fan to the cylinder of the engine. For cooling a muffler of the internal combustion engine, it is known to then direct the cooling air, which has previously cooled the cylinder, to the muffler. Such a cooling air flow is for example from the DE 38 11 181 C2 out.

The invention has for its object to provide a hand-held implement of the generic type, which has an advantageous structure and ensures good cooling.

This object is achieved by a hand-held implement with the features of claim 1.

It is provided to arrange a passage opening in the crankcase facing the rear wall of the fan housing. The peripheral wall of the fan wheel housing has a first end and a second end. The two ends define an outlet for cooling air for the cylinder. The outlet opening extends in the direction of rotation of the fan from the second end to the first end. The passage opening is arranged so that the measured in the direction of rotation from the first end angular distance between the first end and the passage opening is smaller than the measured in the direction of rotation, starting from the passage opening angular distance between the passage opening and the second end. The angular distance is measured in each case as a circumferential angle about the axis of rotation. The angular distance is measured in each case as a distance between one side of the peripheral boundary and one side of the passage opening. Accordingly, the distance is not measured to the center of the passage opening. The passage opening is in this case an opening which is formed separately from the outlet opening and therefore represents an opening which is present in addition to the outlet opening. A cooling air flow flows through the passage opening to the outside of the crankcase and out of the outlet opening to the cylinder of the internal combustion engine. In other words, the cooling air, which flows to the outside of the crankcase through the passage opening, is not preheated by the waste heat of the cylinder, since it does not previously flow over the cylinder. This improves the cooling of the internal combustion engine.

The outlet opening extends in the direction of rotation of the fan in the direction of rotation between the second end and the first end of the peripheral boundary. From the outlet, the air exits to cool the cylinder. The fan promotes cooling air both to the passage opening and to the outlet opening. The fan is bladed advantageous one-sided. However, it can also be provided to provide the fan on both sides with fan blades. The cooling air is advantageous sucked in the ambient air through ventilation slots. In particular, the fan wheel housing designates the space in which the fan wheel of the internal combustion engine is located.

The passage opening is located in the circumferential direction closer to the first end of the perimeter boundary, ie in the direction of rotation at the beginning of the perimeter boundary, as at the second end of the perimeter boundary, ie in the direction of rotation at the end of the perimeter boundary. The passage opening is therefore in the circumferential direction based on the direction of rotation of the fan after the first end and before the second end of the perimeter. Due to the arrangement of the additional passage opening closer to the first end of the peripheral boundary, the total amount of air conveyed by the fan increases. In an arrangement of the passage opening closer to the second end of the perimeter boundary has been shown that this air is diverted from the cooling air flow and thereby the amount of air conveyed to the cylinder is reduced accordingly. The inventive arrangement of the passage opening therefore additional cooling air can be provided without the funded through the outlet opening to the cylinder cooling air is significantly reduced. This improves, for example, the cooling of the entire internal combustion engine, namely the cylinder cooling and the cooling of the muffler space and the crankcase and the space in which the crankcase is arranged.

Advantageously, the angular distance measured in the direction of rotation, starting from the first end, between the first end and the passage opening is less than 120 °, in particular less than 90 °, preferably less than 60 °. Characterized in that the distance between the first end of the peripheral boundary and the passage opening is chosen to be comparatively small, the influence of the volume of air delivered through the passage opening is negligible on the amount of air conveyed through the outlet opening to the cylinder. This arrangement also results in an advantageous Arrangement of the additional passage opening on the side of the crankcase, on which preferably a muffler of the internal combustion engine is arranged.

Advantageously, the passage opening extends at least partially into the rear wall of the fan wheel housing. By virtue of the arrangement in the rear wall of the fan wheel housing, the direction vector, which indicates the main flow direction of the air flowing through the passage opening, has a directional component in the direction of the axis of rotation of the fan wheel and is in particular aligned parallel to the axis of rotation of the fan wheel.

Preferably, the passage opening extends at least partially into the peripheral boundary of the fan wheel housing. It can thereby be achieved that the direction vector, which indicates the main flow direction of the cooling air emerging through the passage opening, has at least one directional component in the radial direction to the axis of rotation of the fan wheel. In particular, the direction vector is oriented perpendicular to the axis of rotation of the fan wheel.

Particularly preferred is an arrangement of the passage opening, in which the passage opening extends partially into the rear wall and partially into the peripheral boundary of the fan wheel housing. By suitable design of the proportions of the passage opening in the rear wall and in the peripheral boundary can be directed in a simple manner, the cooling air flow in the desired direction.

It can be provided that at least one additional guide element for guiding the cooling air flow to the cylinder is connected to the peripheral boundary of the fan wheel housing. The additional guide element projects in particular approximately in the direction of the first end or in the direction of the axis of rotation of the crankshaft. Advantageously, the additional guide element reduces the free flow cross section of the outlet opening.

Advantageously, an elevation protruding into the fan wheel housing is arranged on the rear side of the passage opening in the direction of rotation of the fan wheel. The increase reduces the flow cross section at the rear in the direction of rotation of the fan side of the passage opening. As a result, the increase in the manner of a flow guide element directs cooling air from the interior of the fan wheel housing through the passage opening. By increasing the amount of air flowing through the passage opening is increased. Advantageously corresponds to the front in the direction of rotation contour of the increase in the circumferential profile of the passage opening. The contour of the increase accordingly corresponds to an extension of the peripheral wall of the passage opening. The forward in the direction of rotation contour of the increase is advantageously seamlessly into the passage opening. In a particularly advantageous design, the contour lying in the flow direction of the increase is bent, in particular approximately scoop-shaped, formed.

In an advantageous embodiment, the internal combustion engine has a silencer, wherein the silencer is arranged in a silencer space. The muffler space does not have to be a closed space within a housing of the implement, but designates the area in which the muffler is arranged. Advantageously, the muffler space is partially open to the environment. Preferably, the passage opening connects the interior of the Lüfterradgehäuses with the muffler space. Therefore, a direct cooling of the muffler can be achieved via the passage opening. The cooling air, with which the muffler is cooled, is therefore not first used for cooling the cylinder and then passed to the exhaust muffler. The silencer is supplied directly with cooling air through the passage opening connecting the interior of the fan wheel housing to the silencer compartment. As a result, the cooling air directed to the muffler is not yet preheated by the cylinder, resulting in a particularly effective cooling of the muffler. The silencer is advantageously determined by means of at least one silencer screw at a boundary of the silencer space. The at least one silencer screw is thermal due to the high heat input heavily loaded. About the air flowing through the passage opening the at least one silencer screw can be selectively cooled. This reduces the preload force loss, thus preventing a loosening of the muffler screw. In a particularly advantageous embodiment, the air flowing through the passage opening air is directed by suitable arrangement of the passage opening and / or by at least one cooling fin specifically to the at least one silencer screw.

In a particularly advantageous design limits a portion of the rear wall of the fan wheel with one side of the interior of the Lüfterradgehäuses and with the opposite side of the muffler space. The passage opening is advantageously arranged in this section of the rear wall. The passage opening thereby connects the interior of the Lüfterradgehäuses directly to the muffler space, so that cooling air can pass directly from the Lüfterradgehäuse in the muffler space and cool the muffler. Suitably, a gap is formed between the muffler and a wall of a motor housing of the working device, in which the cooling air flows from the passage opening. In a particularly preferred embodiment, the intermediate space between a resource tank, in particular an oil tank, and the muffler is formed. The wall of the motor housing is preferably a wall of the resource tank. The intermediate space extends in an advantageous design on the underside of the exhaust muffler. The underside of the muffler is the side that is arranged in the usual storage position of the implement below.

In order to achieve an improved cooling effect, it is advantageously provided that at least one cooling rib protrudes into the muffler space. In a particularly preferred embodiment, at least one cooling fin is designed so that it simultaneously causes a stiffening of the motor housing and thus increases the stability of the motor housing.

It has been shown that, in particular in the area of screwing the cylinder to the crankcase, high temperatures can occur during operation, since this range of Of the cooling air flowing around the cylinder is often not sufficiently cooled. In an advantageous embodiment, the cylinder is fixed to the crankcase via at least one cylinder base screw. The cylinder base screw protrudes advantageously into a bore in the crankcase. The air flowing through the passage opening advantageously flows to a wall section of the crankcase adjoining the bore. As a result, an improved cooling of the cylinder base screw is achieved. In order to achieve a further improvement in the cooling of the cylinder base screw, it is advantageously provided that the at least one cooling rib is arranged on the outside of the wall section of the crankcase adjoining the bore. As a result, a particularly good cooling in the region of at least one cylinder base screw is achieved. A further improvement in the cooling of the cylinder base screw is achieved when a muffler plate is arranged between the cylinder and the muffler, which largely separates the muffler space from the cylinder. Advantageously, the muffler plate protrudes to close to the wall of the muffler space and seals the muffler space relative to the cylinder in the area of the cylinder base screws largely. Thereby, a transfer of air, which has been preheated by the cylinder, are largely avoided in the muffler space.

In an advantageous embodiment variant, at least one cooling rib is arranged parallel to the wall of the motor housing delimiting the gap. In a preferred embodiment, the at least one cooling rib extends approximately horizontally in the parking position of the working device. Alternatively, it can also be provided that at least one cooling rib is arranged perpendicular to the wall of the motor housing delimiting the gap. Alternatively, a combination of horizontal and vertical rib may be provided. The use of a cross rib, that is, a plurality of intersecting ribs, can be advantageously provided for cooling.

In order to achieve a favorable cooling air flow, it is advantageously provided that at least one cooling rib on the wall of the motor housing bounding the gap is arranged. The at least one cooling fin is inclined in a particularly preferred embodiment, in particular at an angle of 10 ° to 80 °, preferably at an angle of 20 ° to 70 °, arranged on the wall of the motor housing.

The muffler space advantageously has a first transverse side, which is adjacent to the fan wheel housing, and a second transverse side, which is arranged opposite to the first transverse side. It is advantageously provided that the at least one cooling rib extends up to the first transverse side. As a result, a stiffening of the motor housing is achieved by the cooling fins at the same time. In a particularly preferred embodiment, the at least one cooling rib is integrally formed on the first transverse side. As a result, a good heat dissipation is achieved in the transverse side of the muffler space and in particular in the motor housing. The first and the second transverse side of the muffler space are advantageously formed on the motor housing.

At least one cooling rib is advantageously arranged on the second transverse side of the muffler space. The at least one cooling rib on the second transverse side of the muffler space advantageously serves both for improved cooling and for guiding the cooling air emerging from the passage opening. It can also be provided that at least one cooling rib extends from the first to the second transverse side of the muffler space.

The distance of the peripheral boundary to the axis of rotation is advantageously smaller at the first end than at the second end. Advantageously, the peripheral boundary runs spirally at least in one section. In the subsection, the distance between the peripheral boundary and the axis of rotation of the fan wheel advantageously increases in the direction of rotation of the fan wheel.

Fig. 1

eine perspektivische Darstellung eines handgeführten Arbeitsgeräts in einer Abstellposition,

Fig. 2

eine schematische Schnittdarstellung durch den Antriebsstrang des Arbeitsgeräts aus Fig. 1,

Fig. 3

eine ausschnittsweise Seitenansicht des Motorgehäuses des Arbeitsgeräts aus Fig. 1 mit Zylinder und Schalldämpfer, wobei ein Deckel des Lüfterradgehäuses abgenommen ist,

Fig. 4

eine Seitenansicht des Motorgehäuses entsprechend der Darstellung aus Fig. 3, wobei das Lüfterrad nicht dargestellt ist,

Fig. 5

eine ausschnittsweise perspektivische Darstellung des Motorgehäuses mit Blick in das Lüfterradgehäuse, wobei das Lüfterrad nicht dargestellt ist,

Fig. 6

eine ausschnittsweise Schnittdarstellung durch Motorgehäuse und Schalldämpfer,

Fig. 7

eine ausschnittsweise Schnittdarstellung durch das Motorgehäuse mit daran angeordnetem Lüfterrad entlang der Linie VII-VII in Fig. 6,

Fig. 8

eine Schnittdarstellung entsprechend Fig. 7, wobei das Lüfterrad nicht dargestellt ist,

Fig. 8a und 8b

Ausführungsvarianten in Darstellungen entsprechend Fig. 8,

Fig. 9

eine Seitenansicht in Richtung des Pfeils X in Fig. 3,

Fig. 10

eine perspektivische Darstellung des Schalldämpferraums, wobei der Schalldämpfer nicht dargestellt ist,

Fig. 11

eine perspektivische Schnittdarstellung durch den Schalldämpferraum und das Motorgehäuse,

Fig. 12

eine Schnittdarstellung durch den Schalldämpferraum,

Fig. 13

eine schematische ausschnittsweise Seitenansicht von der dem Lüfterrad abgewandten Querseite des Schalldämpferraums.

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

Fig. 1

a perspective view of a hand-held implement in a parking position,

Fig. 2

a schematic sectional view through the drive train of the implement from Fig. 1 .

Fig. 3

a partial side view of the motor housing of the working device Fig. 1 with cylinder and muffler, with a cover of the fan housing is removed,

Fig. 4

a side view of the motor housing as shown Fig. 3 , where the fan is not shown,

Fig. 5

a partial perspective view of the motor housing with a view into the Lüfterradgehäuse, the fan is not shown,

Fig. 6

a partial sectional view through the motor housing and silencer,

Fig. 7

a partial sectional view through the motor housing with arranged thereon impeller along the line VII-VII in Fig. 6 .

Fig. 8

a sectional view accordingly Fig. 7 , where the fan is not shown,

Fig. 8a and 8b

Variants in representations accordingly Fig. 8 .

Fig. 9

a side view in the direction of arrow X in Fig. 3 .

Fig. 10

a perspective view of the muffler space, wherein the muffler is not shown,

Fig. 11

a perspective sectional view through the muffler space and the motor housing,

Fig. 12

a sectional view through the muffler space,

Fig. 13

a schematic partial side view of the fan wheel remote from the transverse side of the muffler space.

Fig. 1 shows as an exemplary embodiment of a hand-held implement 1, a chainsaw. However, the implement may also be another hand-held, preferably hand-held implement 1 such as a power cutter, a brushcutter, a blower or the like. The implement 1 has a motor housing 2 and a handle housing 3, which has several in Fig. 1 schematically illustrated anti-vibration elements 11 are interconnected. The implement has an internal combustion engine 9, which may be partially formed with the motor housing 2 in one piece. The internal combustion engine 9 is used to drive a tool of the working device 1. The internal combustion engine is advantageously a two-stroke engine. In the exemplary embodiment, the tool is a saw chain 8, which is arranged circumferentially on a guide rail 7 held on the motor housing 2.

The implement 1 comprises a rear handle 4 and a handle tube 6 for guiding the implement 1 during operation. In the exemplary embodiment, the rear handle 4 and the handle tube 6 are part of the handle housing 3 and thereby vibration-decoupled from the engine 9 via the anti-vibration elements 11. At the rear handle 4, a throttle lever 5 is pivotally mounted. The implement 1 also has two resource tanks, namely a fuel tank 10 and an oil tank 48. In the exemplary embodiment, the fuel tank 10 is formed on the handle housing 3. The oil tank 48 is formed on the motor housing 2. The internal combustion engine 9 has a silencer 12. The silencer 12 is advantageously arranged on the side facing away from the rear handle 4 side of the implement 1.

Fig. 1 shows the implement 1 in a storage position 75. In the storage position 75 is the implement 1 with a provided for stopping the implement underside or Absetzfüßen provided for this purpose on a flat, horizontally oriented storage area 76. The storage position 75 is a stable position of the implement 1, in the rear handle 4 and the handle tube 6 are easily accessible to the operator. The working device 1 has a starting device 21 for starting the internal combustion engine 9. In the exemplary embodiment, the starting device 21 is designed as a manually operated cable pull starter. An electrically actuated starter device 21 may also be advantageous.

Fig. 2 shows the drive unit of the working device 1 in detail. The internal combustion engine 9 comprises a cylinder 13 and a crankcase 14. In the cylinder 13, a piston 15 is reciprocally supported. The piston 15 drives via a connecting rod 16 a in the crankcase 14 about a rotational axis 18 rotatably mounted crankshaft 17 at. The crankshaft 17 is connected via a centrifugal clutch 19 with a drive pinion 20 which drives the saw chain 8. With the crankshaft 17 also a fan 22 is rotatably connected. The starting device 21 acts on the crankshaft 17.

In the exemplary embodiment, the centrifugal clutch 19 and the drive pinion 20 are arranged on one side of the crankcase 14 and the fan 22 and the Anwerfvorrichtung 21 on the opposite side of the crankcase 14th

For cooling the internal combustion engine 9 cooling air is conveyed by the fan 22 during operation. Fig. 3 shows the design of the cooling air promotion in detail. As Fig. 3 shows, the fan 22 is disposed in a Lüfterradgehäuse 23. The fan housing 23 is from one in the Fig. 3 not shown crankcase 14 ( Fig. 2 ) facing the rear wall 25 and a peripheral boundary 26 limited. In addition, a cover, not shown, advantageously covers the fan wheel housing 23. The cover advantageously has ventilation slots for sucked by the fan 22 cooling air. The peripheral boundary 26 is advantageously formed as a peripheral wall. The fan 22 is driven in operation in a direction of rotation 24. In the exemplary embodiment, the direction of rotation 24 in the in Fig. 3 shown view in the direction parallel to the axis of rotation 18 and the fan 22 to the crankcase 14 in the counterclockwise direction. The peripheral boundary 26 has a first end 27 and a second end 28. The peripheral boundary 26 extends from the first end 27 in the direction of rotation 24 to the second end 28 advantageously largely uninterrupted. However, it may also be provided that the peripheral boundary 26 between the first end 27 and the second end 28 is interrupted or composed of several sections. In the direction of rotation 24 from the second end 28 to the first end 27, an outlet opening 29 is formed. The outlet opening 29 is bounded by the first end 27 and the second end 28. In the outlet opening 29 advantageously no portion of the peripheral boundary 26 is arranged, so that the outlet opening 29 is not interrupted by the peripheral boundary 26.

During operation, cooling air conveyed by the fan wheel 22 flows through the outlet opening 29 to the cylinder 13 of the internal combustion engine 9. The cylinder 13 has a multiplicity of cylinder cooling ribs 38 which run obliquely in the exemplary embodiment to a cylinder longitudinal axis 74. The cooling air flows from the outlet opening 29 to the cylinder 13 approximately in the direction of arrows 61, which in Fig. 3 are shown schematically. From the cylinder 13 can advantageously flow a part of the cooling air to a top 73 of the muffler 12. The upper side 73 of the silencer 12 is the side which lies in the parking position 75 away from the storage area 76.

The peripheral boundary 26 and the rear wall 25 of the Lüfterradgehäuses 23 define an interior 41 of the Lüfterradgehäuses 23. In the interior 41 is the fan 22 arranged. From the inner space 41, the outlet opening 29 leads. The peripheral boundary 26 runs spirally around the axis of rotation 18 of the crankshaft 17 (at least in one section 49). Fig. 2 ). In the exemplary embodiment, the spiral portion 49 extends in the direction of rotation 24 from the first end 27 to a region 50. The portion 49 extends in the embodiment over a circumferential angle about the axis of rotation 18 of slightly more than 90 °. At the first end 27, the peripheral boundary 26 has a distance a from the axis of rotation 18. At the area 50, the peripheral boundary 26 has a distance b from the axis of rotation 18. The distance b in the area 50 is advantageously greater than the distance a in the section 49th

In Fig. 3 is also a coordinate system with axes x and y drawn. In the side view shown with a view parallel to the axis of rotation 18 of the crankshaft 17 (FIG. Fig. 2 ), the origin of the coordinate system lies on the axis of rotation 18. The y-axis extends in the direction from the axis of rotation 18 to the second end 27. The x-axis is arranged at right angles thereto. The x-axis is oriented so that the positive x-axis comes in 90 degree counterclockwise rotation with the positive y-axis after pivoting. The axes x and y divide the implement 1 into four sectors I, II, III and IV. The sector I is bounded by the positive y-axis and the negative x-axis, the sector II by the negative x-axis and the negative y-axis, the sector III of the positive x-axis and the negative y-axis and the sector IV of the positive x-axis and the positive y-axis. The outlet opening 29 extends at least partially, in the embodiment completely in the fourth sector IV. The second end 28 of the peripheral boundary 26 is arranged in the fourth sector IV in the exemplary embodiment. The spiral section 49 of the peripheral boundary 26 extends in the first sector I. In the exemplary embodiment, the section 49 extends into the second sector II. It can also be provided that the spiral section 49 into the third sector III or to the second End 28 extends. The muffler 12 is advantageously arranged in the first sector I. The oil tank 49 extends in the first sector I and in the second sector II Fig. 3 Also, a fuel cap 47 of the oil tank 48 is shown.

As Fig. 3 shows, in the third sector III an ignition module 44 is arranged, which is connected via an ignition cable 45 with a projecting into a combustion chamber of the internal combustion engine 9 spark plug 46. The fan 22 carries in Fig. 3 not shown magnets that induce in the ignition module 44, the ignition voltage for the spark plug 46.

The second end 28 has to the axis of rotation 18 of the crankshaft 17 (FIG. Fig.2 ) a distance c which is greater than the distance a and also greater than the distance b. It can be provided that the distance c is the largest distance of the peripheral boundary 26 to the axis of rotation 18. In the exemplary embodiment, however, the peripheral boundary 26 has an even greater distance from the axis of rotation 18 in the region of the ignition module 44, since the flow cross section in the fan wheel housing 23 is reduced in this region on account of the ignition module 44. The rear wall 25 is advantageously formed closed except for one or more passage openings for cooling air, which will be described in more detail below. In the Fig. 3 shown, formed in the rear wall 25 receiving opening 58 for an anti-vibration element 11 is advantageously closed by the anti-vibration element.

As Fig. 3 shows, the rear wall 25 has a passage opening 30. The passage opening 30 is formed separately from the outlet opening 29. Through the passage opening 30 additional cooling air is passed to the muffler 12. The passage opening 30 is an additional opening for cooling air. The muffler 12 is arranged in a muffler space 32 into which the passage opening 30 opens.

At the side lying behind the passage opening 30 with respect to the direction of rotation 24 79 ( Fig. 4 ) of the passage opening 30 is advantageously arranged an elevation 31. The increase 31 points in the in Fig. 3 shown side view of an approximately triangular cross-section.

As Fig. 3 also shows, connects to the perimeter boundary 26 at the second end 28 a partition 57, which has a in Fig. 3 Not shown suction chamber of the engine 9 separates from the cylinder 13. In the suction advantageously an air filter and the fuel supply are arranged. The fuel supply can advantageously take place via a carburetor arranged in the intake chamber or via a fuel valve. Also, the fuel valve may be arranged in the suction chamber. For cooling the intake space and / or for cooling a fuel valve may in Fig. 3 a cooling air opening 77 shown in dashed lines 77 may be provided in the rear wall 25. The cooling air opening 77 is advantageously arranged in the third sector III and / or fourth sector IV, that is, it is located significantly closer to the second end 28 than to the first end 27.

Fig. 4 shows the side view of the motor housing 2 from Fig. 3 fragmentary and without arranged in the fan housing 23 fan 22th Like Fig. 4 shows, the first end 27 has an angular distance α to the passage opening 30. The angular distance α is measured in the direction of rotation 24, starting from the first end 27 to the front in the direction of rotation 24 side 78 of the passage opening 30. The angular distance α is advantageously less than 120 °, in particular less than 90 °, preferably less than 60 °. In the exemplary embodiment, the angular distance α is less than 50 °. The measured in the direction of rotation 24, starting from the passage opening 30 angular distance β between the passage opening 30 and the second end 28 is significantly larger than the angular distance α. The angular distance β is measured from the direction of rotation in the rear side 79 of the passage opening 30 to the second end 28 of the peripheral boundary 26. The angular distance β is advantageously more than 90 °, in particular more than 180 °. In the exemplary embodiment, the angular distance β is more than 210 °. As Fig. 4 Also shows, adjacent to the rear side 79 of the passage opening 30, the elevation 31 is arranged. In Fig. 4 is also a arranged in the fan housing 23 air guide 54 is shown, which will be described in more detail below.

As Fig. 4 schematically shows with dashed lines, in an advantageous embodiment, a portion of the peripheral boundary 26 may be formed by a guide member 83 which projects into the Lüfterradgehäuse 23. The guide element 83 protrudes in particular approximately in the direction of the axis of rotation 18 of the crankshaft 17 or in the direction of the first end 27. The guide element 83 reduces the free flow cross section of the outlet opening 29. On the guide element 83, the second end 28 'of the peripheral boundary 26 is formed. The outlet opening 29 extends in this embodiment in the direction of rotation from the second end 28 'to the first end 27th

The increase 31 points how Fig. 4 shows, viewed in the direction parallel to the axis of rotation 18 of the crankshaft 17 seen an approximately triangular shape. Fig. 5 shows the design of the elevation 31 in detail. The elevation 31 has a contour 63 lying in the direction of rotation 24 at the front. The contour 63 advantageously corresponds to the circumferential profile of the passage opening 30 and preferably merges into the peripheral wall of the passage opening 30. The contour 63 is formed as a flow guide, which branches off a portion of the funded by the fan 22 cooling air. The elevation 31 can advantageously extend over up to 50% of the free flow cross section between peripheral boundary 26 and impeller 22 at the passage opening 30. In an advantageous embodiment, the width of the increase decreases with increasing distance from the rear wall 25 of the fan wheel housing 23. The increase 31 is therefore narrower with increasing distance from the rear wall 25. In an advantageous embodiment, the increase in the viewing direction approximately in the circumferential direction and approximately parallel to the peripheral boundary 26 at the passage opening 30 has an approximately triangular shape. Advantageously, in a viewing direction in the parking position 75 (FIG. Fig. 1 ) vertically downwards an approximately triangular shape of the elevation 31.

As Fig. 5 also shows, the air guide member 54 extends mainly in the fourth sector IV and extends into the third sector III. As Fig. 5 shows, on the air guide member 54, an air inlet opening 55 is formed, is branched off via the combustion air from a region of the interior 41 of the fan housing 23, in the air has little pollution. About the air guide 54, the clean combustion air is guided in the suction space, not shown. The combustion air is then supplied during operation fuel for the operation of the internal combustion engine. The air guide 54 projects in the exemplary embodiment through the outlet opening 29 and thereby reduces the free flow cross section of the outlet opening 29th

Like the sectional view in Fig. 6 shows, the passage opening 30 opens into the muffler space 32. The muffler 12 has an underside 80 which in the parking position 75 (FIG. Fig. 1 ) is the area of the muffler 12 which has the smallest distance to the storage area 76. Between the bottom 80 and the motor housing 2, a gap 35 is formed. The intermediate space 35 is bounded by a wall 34 of the motor housing 2. In the exemplary embodiment, the wall 34 is a wall of the oil tank 48. Through the passage opening 30, a cooling rib 51 can be seen, which will be described in more detail below.

As Fig. 7 shows, the cooling air exits from the interior 41 of the fan housing 32 through the passage opening 30 in a direction schematically indicated by an arrow 62 flow direction in the muffler space 32. The muffler 12 is adjacent to its underside 80 (FIG. Fig. 6 ) to mounting domes 59 of the motor housing 2 ( Fig. 7 ) screwed. These are in Fig. 9 shown muffler screws 82 screwed into the mounting dome 59. The fixing domes 59 are arranged in the embodiment in the intermediate space 35. As Fig. 7 Also, the muffler space 32 is bounded by a first transverse side 39 and a second transverse side 40. The first transverse side 39 is adjacent to the Lüfterradgehäuse 23. The second transverse side 40 is located on the opposite side, ie adjacent to the in Fig. 7 not shown guide rail 7 ( Fig. 1 ). In the exemplary embodiment, the transverse sides 39 and 40 are part of the motor housing 2. Advantageously, the transverse sides 39 and 40 of the muffler space 32 formed on the crankcase 14 and extend in extension of the transverse sides of the crankcase 14th

The fastening domes 59 are fixed to the transverse sides 39 and 40 of the muffler space 32. The fastening domes 59 and the muffler screws 82 are cooled via the air flowing into the muffler space 32 through the passage opening 30.

As Fig. 7 Also shows, the crankcase 14 has a wall portion 56 which limits the muffler space 32. The wall portion 56 simultaneously defines the crankcase interior 81. The cylinder 13 (FIG. Fig. 2 ) is fixed to the crankcase 14 via cylinder base screws 37, which are screwed into bores 36 of the crankcase 14. In Fig. 7 three of the four cylindrical foot screws 37 are shown. At the outside of the wall portion 56 delimiting the muffler space 32, at least one cooling fin 51 is preferably arranged. Advantageously, the at least one cooling rib 51 is integrally formed on the wall section 56. Particularly advantageous is the at least one cooling fin 51 is arranged adjacent to a bore 36. As a result, an improved cooling of the cylinder base screws 37 is achieved. The cooling rib 51 preferably protrudes into the muffler space 32. In the exemplary embodiment, the cooling fins 51 extend as far as the transverse side 40 and have a spacing from the transverse side 39. At the same time, the stability of the motor housing 2 is increased via the cooling rib 41.

The Fig. 7 and 8th also show the design of the passage opening 30 in detail. The passage opening 30 extends in the embodiment in both the rear wall 25 and in the peripheral boundary 26. As a result, the cooling air flows from the interior 41 in a direction obliquely to the axis of rotation 18 in the muffler space 32. The vector of the flow direction therefore has both direction components parallel to the axis of rotation 18 and direction components perpendicular to the axis of rotation 18. By this orientation of the flow direction, both the cylinder base screws 37 and the muffler screws 82 can be well cooled by the cooling air flowing into the muffler chamber 32.

The Fig. 8a and 8b show alternative designs of the passage opening. Fig. 8a shows a passage opening 64 which extends exclusively in the rear wall 25. In this configuration, the cooling air flows in the direction of an arrow 65 approximately parallel to the axis of rotation 18 in the muffler space 32. The arrow 65, which corresponds to the vector of the main flow direction, has no or only very small direction components perpendicular to the axis of rotation 18th

According to the embodiment Fig. 8b a passage opening 66 is provided which extends exclusively in the peripheral boundary 26. Through this passage opening 66, the cooling air flows in the direction of an arrow 67, which is directed approximately perpendicular to the axis of rotation 18. The arrow 67 is the vector of the main flow direction and has no or only very small directional components parallel to the axis of rotation 18. By changing the position of the passage opening 30, 64, 66, the main flow direction of the exiting in the muffler chamber 32 cooling air can be changed. In a particularly advantageous embodiment, the passage opening 30, 64 extends at least partially into the rear wall 25, so that the muffler 12 is cooled in the region of its underside 80 over its entire width.

Fig. 9 shows the arrangement of the muffler 12 in the muffler space 32. Wie Fig. 9 shows, between the bottom 80 and the wall 34 of the oil tank 48, the gap 35 is formed. The muffler 12 fills the muffler space 32 between the transverse sides 39 and 40 largely, so that an approximately uniform gap is formed around the muffler 12 through which the cooling air can flow.

As Fig. 10 shows, a muffler plate 68 is fixed to the cylinder 13. The muffler plate 68 has an opening 70 which is disposed at an outlet 71 of the cylinder 30. Through the opening 70, the exhaust gases of the internal combustion engine 9 from the cylinder 13 in the muffler 12 ( Fig. 9 ) out. The muffler plate 68 has a plurality of stiffening beads 69 for increasing the stability. As Fig. 10 shows the muffler plate 68 extends laterally to the transverse sides 39 and 40. A passage of cooling air from the cylinder 13 directly to the bottom 80 ( Fig. 9 ) of the muffler 12 is thereby largely avoided. The underside 80 of the muffler 12 is cooled by cooling air, which passes through the passage opening 30 directly from the interior 41 of the muffler housing 23 in the muffler space 32. The cooling of the underside 80 of the muffler 12 is therefore carried out with cooling air, which was not previously heated by the cylinder 13. The cylinder 13 and the bottom 80 of the muffler 12 are cooled by separate cooling air streams.

In Fig. 10 also the partition 57 is shown to the suction. As Fig. 10 Also shows, has the mounting dome 59, which is held on the wall 34 and the transverse side 39 of the muffler space 32, a cooling fin 60, with which it is supported on the wall 34. The in Fig. 10 not shown Befestigungsdom 59 on the transverse side 40 is provided in a corresponding manner with a cooling fin 60. As a result, on the one hand the stability of the connection of the fastening dome 59 is increased and on the other hand an improved cooling of the fastening dome 59 is achieved. As Fig. 10 also shows, more cooling fins 53 are provided on the transverse side 39. The cooling ribs 53 are guided along the outer side of the peripheral boundary 26 and the rear wall 25 of the fan housing 22 and improve cooling on the transverse side 39. The longitudinal direction of the cooling ribs 53 extends approximately parallel to the axis of rotation 18. The cooling ribs 53 protrude from the rear side of the rear wall 25 and the perimeter boundary 26 in the muffler space 32nd

Fig. 11 shows the arrangement of the cooling fins 51 on the transverse side 40 and the arrangement of the cooling fins 53 on the opposite transverse side 39. Wie Fig. 11 Also shows, the passage opening 30 is disposed in a portion 33 of the rear wall 25, which limits the interior 41 of the Lüfterradgehäuses 23 with one side 42 and the opposite side 43 the muffler space 32. The air flows through this from the interior 41 through the section 33rd the rear wall 25 directly into the muffler space 32nd

As Fig. 12 shows, the motor housing 2 has a parting plane 72. In the embodiment, two cooling fins 51 are provided. The adjacent to the wall 34 arranged cooling rib 51 extends approximately to the parting plane 72. The farther from the wall 34 remote cooling rib 51 is formed shorter and does not extend in the embodiment to the parting plane 72. The cooling fins 53 are formed in the embodiment comparatively short and end at a distance from the dividing plane 72. However, cooling fins 53 ', which are shown schematically, may also be provided, which extend further in the direction of the transverse side 40, preferably to approximately the dividing plane 72.

Fig. 13 shows a side view of the transverse side 40 seen from the opposite transverse side 39 from. As Fig. 13 shows, project the cooling fins 51 to close to the mounting dome 59 of the muffler 12th Fig. 13 also shows the cooling fin 60 on the mounting dome 59 on the second transverse side 40. Die Fig. 13 also shows, the wall 34 may also carry other cooling fins 52 which in Fig. 13 are shown schematically. The cooling fins 52 protrude from the wall 34 into the muffler space 32. The fins 52 are preferably inclined to the wall 34 by an angle of less than 90 °. The inclination of the cooling ribs 52 is advantageously provided so that the cooling fins 52 have a smaller distance from the wall portion 56 of the crankcase 41 with increasing distance from the wall 34.

The cooling fins 51 extend in the exemplary embodiment parallel to the wall 34 of the muffler space 32, while the cylinder cooling fins 38 are inclined thereto. This is especially in Fig. 6 recognizable. The cooling ribs 51, which are formed on the crankcase 14, therefore do not run parallel to the cylinder cooling ribs 38.

The fact that the wall 34 carries the fixing dome 59 for the muffler 12, the fixing domes 59 are well cooled via the exiting through the passage 30 cooling air flow. In the exemplary embodiment, the cooling fins 51, 52, 53, 53 ' designed as elongated ribs. However, cross-shaped or differently designed cooling fins may also be advantageous.

The passage opening 30 allows largely separate cooling air streams for the cylinder 13 and the muffler 12, in particular for the underside 80 of the muffler 12. As a result, an improved cooling of the muffler 12 is achieved. Characterized in that the passage opening 30 has only a small circumferential distance to the first end 27 of the peripheral boundary 26, resulting from the passage opening 30, no reduction in the amount of air delivered through the outlet opening 29, but the funded with the fan 22 total amount of air is increased.

The passage opening 30 is advantageously significantly smaller than the outlet opening 29. The flow cross section of the passage opening 30 is preferably less than 50%, in particular less than 30%, of the outlet opening 29. Advantageously, the flow cross section of the passage opening 30 is smaller than 16 cm ² , in particular smaller than 9 cm ² . The passage opening 30 may have a circular or elliptical cross section. However, another cross-sectional shape for the passage opening 30, in particular a rectangular cross-sectional shape or a cross-sectional shape similar to a rectangular cross-sectional shape may also be advantageous.

Claims (16)

Hand-operated implement with an internal combustion engine (9) and with a fan wheel (22) for conveying cooling air for the internal combustion engine (9), wherein the internal combustion engine (9) has a cylinder (13) and a crankcase (14), wherein the fan wheel (22 ) is arranged in a Lüfterradgehäuse (23) and of the internal combustion engine (9) in a rotational direction (24) is driven in rotation, wherein the Lüfterradgehäuse (23) to the crankcase (14) of the internal combustion engine (9) facing the rear wall (25) and a peripheral boundary (26), wherein the peripheral boundary (26) has a first end (27) and a second end (28, 28 '), the first end (27) and the second end (28, 28') having an exit opening (29 ) for the cylinder (13) to promote cooling air, wherein the outlet opening (29) in the direction of rotation (24) from the second end (28, 28 ') to the first end (27), wherein in the fan housing (23) has a additional passage opening (30, 64, 66) is provided, flows via the cooling air from the Lüfterradgehäuse (23) to the outside of the crankcase (14),
characterized in that in the direction of rotation (24) measured from the first end (27) angular distance (α) between the first end (27) and the passage opening (30, 64, 66) is smaller than that in the direction of rotation (24) starting measured angular distance (β) between the passage opening (30, 64, 66) and the second end (28, 28 ') of the passage opening (30, 64, 66), wherein the angular distance (α, β) each as a circumferential angle about the axis of rotation (18) is measured. Working device according to claim 1,
characterized in that in the direction of rotation (24) measured from the first end (27) angular distance (a) between the first end (27) and the passage opening (30, 64, 66) is less than 120 °. Tool according to claim 1 or 2,
characterized in that the passage opening (30, 64) extends at least partially into the rear wall (25) of the fan wheel housing (23). Tool according to one of claims 1 to 3,
characterized in that the passage opening (30, 66) extends at least partially into the peripheral boundary (26) of the fan wheel housing (23). Tool according to one of claims 1 to 4,
characterized in that on the in the direction of rotation (24) of the fan (22) rear side (79) of the passage opening (30, 64, 66) in the Lüfterradgehäuse (23) projecting increase (31) is arranged. Tool according to one of claims 1 to 5,
characterized in that the internal combustion engine (9) comprises a muffler (12), wherein the muffler (12) in a muffler space (32) is arranged and wherein the passage opening (30, 64, 66) the interior of the fan housing (23) with the Silencer room (32) connects. Working device according to claim 6,
characterized in that a portion (33) of a wall of the fan wheel housing (23) with one side (42) the interior (41) of the Lüfterradgehäuses (23) and with the opposite side (43) the muffler space (32) limited, wherein the passage opening (30, 64, 66) in this section (33) of the wall of the Lüfterradgehäuses (23) is arranged. Tool according to claim 6 or 7,
characterized in that between the muffler (12) and a wall (34) of a motor housing (2) of the working device, a gap (35) is formed, in which the cooling air from the passage opening (30, 64, 66) flows. Tool according to one of claims 6 to 8,
characterized in that at least one cooling rib (51, 52, 53) is provided, which projects into the muffler space (32). Tool according to claim 9,
characterized in that the cylinder (13) via at least one cylinder base screw (37) on the crankcase (14) is fixed, wherein the cylinder base screw (37) in a bore (36) in the crankcase (14) protrudes, and that the at least one cooling fin (51) on the outside of the bore (36) adjacent wall portion (56) of the crankcase (14) is arranged. Tool according to claim 9 or 10,
characterized in that the at least one cooling rib (51) runs parallel to the wall (34) of the motor housing (2) delimiting the intermediate space (35). Tool according to one of claims 9 to 11,
characterized in that the at least one cooling rib (52) on the intermediate space (35) bounding wall (34) of the motor housing (2) is arranged. Tool according to one of claims 9 to 12,
characterized in that the muffler space (32) has a first transverse side (39) adjacent the fan wheel housing (23), the muffler space (32) having a second transverse side (40) disposed opposite the first transverse side (39) in that the at least one cooling rib (51, 52) extends as far as the first transverse side (39). Tool according to one of claims 1 to 13,
characterized in that at least one cooling rib (53) on the second transverse side (40) of the muffler space (32) is arranged. Tool according to one of claims 1 to 14,
characterized in that the distance (a, c) of the perimeter boundary (26) to the axis of rotation (18) at the first end (27) is smaller than at the second end (28, 28 '). Tool according to one of claims 1 to 15,
characterized in that the peripheral boundary (26) extends spirally at least in a section (49), wherein the distance (a, b) of the peripheral boundary (26) to the axis of rotation (18) of the fan (22) in the section (49) in Direction of rotation (24) of the fan wheel (22) increased.

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