JP2000052280A - Manual operation type work equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve work equipment in such a way that its capacity is made small as much as possible, and both its operation condition and the output of an internal combustion engine can be improved. SOLUTION: In case of a manual operation type work equipment, particularly, a chain saw or a similar article, combustible air is exhausted in the axial direction out of an inlet 11 covered by a fan rotor 5 provided for the bottom of a casing 7 formed in the radial direction with respect to a crank shaft 4, through a space partitioned by the bottom of the case 7 and an end face attached with the vanes of the rotor 5, so that it can be fed to an air filter 18 through a combustible air duct 9. The combustible air duct 9 is branched from a fan casing 6 in the tangential direction with respect to the rotary direction of the fan rotor 5, and is directly extended to the air filter 18, and the inlet area of the combustible air duct 9 is partitioned by the bottom of the casing 7 and an overlapping duct wall 8 as a double bottom composed of the bottom of the casing 7, and of the fan casing 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises an internal combustion engine disposed in an equipment casing, wherein a crankshaft of the internal combustion engine drives a tool and a fan rotor, and the fan rotor is disposed in the fan casing. Cooling air is sucked in from the inlet and supplied to the internal combustion engine, and combustion air is provided at the casing bottom formed in the radial direction with respect to the crankshaft. The invention relates to a manually operated work device, in particular a chainsaw or the like, which can be discharged axially through the space defined by the end face with the end and provided to the air filter via a combustion air duct.

[0002]

BACKGROUND OF THE INVENTION Published German Patent Application No. 196
From the publication 18669, there is known a working machine, in particular a brush cutter for cutting grass and bushes. An air-cooled internal combustion engine is arranged in an equipment casing of the work equipment. The crankshaft of the internal combustion engine drives the cutter of the work equipment provided at the end of the guide rod. In the fan casing, a double-suction type fan rotor is arranged at the other end of the crankshaft. The end faces of the fan rotor each have a blade ring. The vanes located on the outside with respect to the internal combustion engine form a fan rotor for supplying cooling air to the internal combustion engine. The combustion air forms a stream separate from the cooling air and is discharged axially through an opening formed in the casing bottom formed radially to the crankshaft and covered by a fan rotor. From the space defined by the casing bottom and the bladed end face of the fan rotor, combustion air already warmed and relatively free of polluting particles can be supplied to the air filter via a combustion air duct.

[0003] In the case of known working equipment, a suction port is formed in the casing bottom of the fan casing. This suction port is provided on the side of the crankshaft opposite to the internal combustion engine. The fan rotor is spaced from the casing bottom. Therefore, an intermediate chamber is formed between the casing bottom and the blade ring inside the fan rotor. Ambient air around the crankcase of the internal combustion engine arranged adjacent to the suction port is sucked into this intermediate chamber. A combustion air outlet is provided at the bottom of the casing in front of the suction port in the rotation direction of the fan rotor. This combustion air outlet
A combustion air duct leading to an air filter of the internal combustion engine is connected.

[0004] For normal operation of the work equipment, it is necessary to dispose the fan casing or its casing bottom in the direction of the crankshaft axis with respect to the fan rotor and the internal combustion engine. Thereby, predetermined combustion air supply can be realized. The spaced arrangement of the components increases the width of the work equipment, thereby limiting the handling operability of the work equipment. Similarly, the combustion air duct in the first section, axially from the combustion air outlet,
That is, it is guided perpendicularly to the casing bottom into the drive unit of the work equipment and is bent in an L-shape with respect to the air filter in the second section. The curved shape of the combustion air duct increases the flow resistance of the combustion air. Output loss and torque loss of the internal combustion engine will occur. In addition, long combustion air ducts of the known type are excited by the flowing air.

[0005]

The object underlying the present invention is to provide a work implement of the type mentioned at the outset in such a way that the volume is as small as possible and the operating conditions of the work implement and the output of the internal combustion engine are improved. It is to improve.

[0006]

This object is achieved according to the invention by the features of claim 1. The combustion air duct branches off from the fan casing substantially tangentially to the direction of rotation of the fan rotor and extends straight to the air filter. Thereby, the flow path of the combustion air is shortened, and the flow resistance of the combustion air duct is reduced. The inlet area of the combustion air duct is defined by the casing bottom and a duct wall overlapping the casing bottom as a double bottom of the fan casing, whereby the structural group consisting of the fan casing and the combustion air duct is axially aligned with respect to the crankshaft axis. It has a small structural volume in the direction.
The fan housing can be arranged directly adjacent to the internal combustion engine or its crankcase, so that the drive unit of the working equipment can be made compact.

If the flow cross section of the combustion air duct is enlarged in the flow direction, at any point of operation, sufficient air reaches the air filter case of the internal combustion engine without flow resistance. The pulsation of the combustion air flow due to the periodic operation of the internal combustion engine is prevented by the short length of the combustion air duct and the large flow cross section. The air filter case of the internal combustion engine and the fuel distribution device or the mixture forming device can be arranged directly adjacent to the internal combustion engine. This is because these parts do not vibrate due to the arrangement according to the invention.
The combustion air duct has a flat entrance area. In this case, the combustion air duct wall forming the double casing bottom of the fan casing can be arranged closely to the internal combustion engine. When the cross section of the combustion air duct is expanded parallel to the casing bottom by widening the inlet area,
The structural group consisting of the fan casing and the combustion air duct can be made flat. It is expedient if the combustion air duct has a rectangular cross section. Thereby, the side of the wall located closer to the internal combustion engine can be formed in a planar shape. Therefore, the fan casing can be fitted to the drive journal of the crankshaft for the fan rotor near the internal combustion engine.

[0008] Advantageously, an inlet formed in the casing bottom and leading to the combustion air duct extends in an arc in the direction of rotation of the fan rotor. This allows air to enter the combustion air duct unimpeded from the space defined between the fan lower and the casing bottom. In this case, the end of the inlet located forward in the direction of rotation extends far and forms a cross-sectional extension in the inlet area of the combustion air duct which is formed flat on the rear side of the fan casing. The front end of the inlet is preferably provided adjacent to the plane of the outer circumferential surface of the combustion air duct formed near the crankshaft. The end of the inlet, which is located on the front side in the direction of rotation of the fan rotor, is arranged on the side of the crankshaft opposite to the internal combustion engine, and allows a fast entry into the combustion air duct.

In the area of the entrance of the combustion air duct formed by the double casing bottom behind the fan casing, the cross-sectional extension of the combustion air duct, which is formed flat over the entire radius of the casing bottom, increases relative to the casing bottom. Advantageously, this is achieved by increasing the width in parallel. Outside the duct section overlapping the casing bottom, the combustion air duct is expanded in the axial direction.
In this case, the duct wall is connected beyond the plane of the bottom of the casing to the peripheral wall of the fan casing which overlaps the fan rotor in the axial direction.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS Further features of the invention are evident from the dependent claims and the following description of an embodiment based on the drawings.

FIG. 1 schematically shows a manually operated engine chainsaw 1. The drive unit 40 of the chainsaw drives a saw chain (tool) 41 that rotates and rotates on the guide rail. The internal combustion engine 2 is arranged in the device casing 17 of the drive unit 40. This internal combustion engine is an air-cooled two-stroke engine in the illustrated embodiment. The crankshaft 4 supports a chain pinion for driving the saw chain 41 on the invisible side of the internal combustion engine 2. On the opposite side, the pins of the crankshaft 4 guided out of the internal combustion engine 2 support a fan rotor 5 for supplying cooling and combustion air to the engine. This fan rotor 5 is arranged in a fan casing 6.
This fan casing is formed as an air guide spiral body open on the internal combustion engine 2 side. The combustion air for the internal combustion engine 2 is discharged axially through an inlet 11 formed in the casing bottom 7 of the fan casing 6 and is guided through a combustion air duct 9 to an air filter case 19. The air from which relatively dust has been relatively removed passes from the return chamber between the fan rotor 5 and the casing bottom 7 to the inside of the contamination chamber 21 of the air filter case 19 through the axial air discharge portion. The air filter case 19 and the air filter 18 arranged therein are closed by a removable lid 20. A carburetor (not shown) is provided between the air filter case 19 and the internal combustion engine 2. This vaporizer mixes the filtered clean air stream with fuel before forming the cylinder 3 to form a mixture. This fuel is taken out of the fuel tank 23. An internal combustion engine 2;
The other components of the drive unit 40 are compactly arranged and fixed to the support beam 13 of the chainsaw 1.
In order to accommodate the compact drive unit 40, the equipment casing 17 has a relatively small volume. Thereby, the manual operability of the engine chainsaw 1 is improved.

The fan rotor 5 is formed as a double suction type. In this case, one blade ring 30, 31 is formed on each end face of the fan rotor 5. The rotating blades of the blade rings 30, 31 are fixed to a common base. By this, this base becomes blade ring 3
A partition 36 between 0 and 31 is formed. The rotating blades of the blade ring 31 on the opposite side of the internal combustion engine 2 with the fan rotor 5 installed draw fresh air into the fan casing 6. The centrifugally accelerated cooling air flow is guided toward the cooling ribs of the internal combustion engine 2 along the peripheral wall 12 of the fan casing 6 overlapping the fan rotor 5 in the axial direction. This cooling rib is used for the cylinder 3 of the internal combustion engine 2.
The combustion heat generated inside is derived.

The combustion air duct is defined in the inlet region immediately behind the inlet 11 by a casing bottom 7 and a duct wall 8 which overlaps the casing bottom 7 as a double bottom of the fan casing. The combustion air duct branches off the fan casing 6 substantially tangentially to the direction of rotation 15 of the fan rotor 5 and extends straight, thereby reaching the air filter case 19 at the shortest distance. The inlet 11 extends in an arc shape in the rotation direction 15 of the fan rotor 5. The inlet 11 is guided in the direction of rotation 15 as long as possible. Thereby, at the same time, the duct cross section of the combustion air duct 9 continuously expands to have a large opening cross section. The combustion air flows from the inlet into the area of the inlet of the combustion air duct 9 formed by the double bottom and reaches the air filter case 19 at the shortest distance without being disturbed by the continuous expansion of the duct cross section. The passage cross section of the combustion air duct 9 ideally spreads uniformly in the flow direction. However, it can be expanded differently, depending on the structural provision of the space provided with the drive unit. Advantageously, the outlet cross section before the air filter is approximately five times the inlet cross section.

The connection end 14 of the straight combustion air duct 9 is connected to a connection short pipe 16 of an air filter case 19. The large passage cross section and the short length of the combustion air duct 9 allow the combustion air to enter the air filter case 19 without any actual obstruction, thereby greatly reducing the vibrational excitation by the pulsating suction internal combustion engine. Nevertheless, the connection end 14 of the combustion air duct 9
A sleeve for further eliminating vibration can be inserted between the air filter case 19 and the connecting short pipe 16.

The oscillating gap between the internal combustion engine and the fan casing or carburetor, as is customary in the case of conventional drive units for manually operated work equipment, is not necessary in the case of the device according to the invention. is there. Air filter case 19
Is at least five times the stroke volume of the cylinder 3. As a result, the pulsating suction of air during the working cycle of the internal combustion engine 2 causes the air filter 1
8 is maintained without affecting the air transport.

The drive unit 40 is extremely compact due to the flat shape of the combustion air duct 9.
In this case, the flat casing bottom 8 of the fan casing 6
Is provided immediately next to the internal combustion engine 2 or a crankcase that is not visible to the internal combustion engine. The flat combustion air duct 9 extends in the flow direction behind the fan casing 6 parallel to the casing bottom, thereby increasing the passage cross section. Outside the plane covered by the casing bottom 7, the duct wall 8 is connected to the peripheral wall 12 beyond the plane of the casing bottom, thereby additionally increasing the passage cross section of the duct.

FIG. 2 is a perspective view showing the fan casing 6 to which the combustion air duct 9 is connected. The combustion air duct 9 has a rectangular cross section. In this case, the end faces 35 of the duct walls 8 facing each other in the direction of the crankshaft axis 29 lie in the same plane as the casing bottom 7 of the fan casing 6. Crank rotation direction 1 around axis 29
The end 24 of the inlet 11 which is located forward in 5 is located on the side of the crankshaft opposite the internal combustion engine. The inlet 11 extends in an arc around the crankshaft axis 29 and is separated from the peripheral wall 12 of the fan casing 6. Thereby, the dust-free combustion air near the bottom reaches the inside of the combustion air duct from the center of the fan casing 6. The influence on the combustion air flow by the air flow guided in the peripheral wall 12 towards the cooling air outlet 22 is closed off.

The inlet 11 is as long as possible in the direction of rotation 15 and its end 2 is located forward of the direction of rotation 15.
5 is formed to be sharp. As a result, the largest possible cross section of the inlet 11 is obtained. The edge 26 of the inlet 11 forming a pointed end 25 is adjacent to the plane of the side surface 28 of the combustion air duct 9 and extends substantially linearly. A protrusion 34 of the combustion air duct 9 is formed in an end region of the air guide spiral body 6 near the cooling air outlet 22 of the peripheral wall 12. The projection projects axially from the casing bottom 7, and its end face is located in substantially the same plane as the casing bottom 7 and the end face 35 of the duct wall 8. End face 3 of duct wall 8
5 is connected to the outer surface of the peripheral wall 12 on the other side of the plane of the casing bottom 7. The arcuate protrusions 34 located between the inlet 11 and the peripheral wall 12 create another volume in the combustion air duct and reduce the resistance of the combustion air duct. A circular flange 33 for connecting an air filter case is formed at an end of the combustion air duct 9.

The duct wall 8 forms a double bottom 27 behind the casing bottom 7 and defines a combustion air duct in front of the inlet 11. The double bottom 27 is formed flat near the front end 24 of the inlet 11 in the inlet area of the duct 9. Thereby, the fan casing 6 near the internal combustion engine 2 can be arranged. The distance between the casing bottom 7 and the double bottom 27 is increased by the bent portion 32. This bend is in the corner (triangle) of the entrance 11. This square part can be set corresponding to the volume of the crankcase of the internal combustion engine, which is arranged adjacent to the housing bottom 7 in the installation position of the fan housing. The section of the combustion air duct behind the casing bottom 7 thereby extends next to the crankcase and projects into the space between the other equipment, which is normally exposed in the drive unit.

FIG. 3 shows the fan casing 6 to which the combustion air duct 9 is connected from behind. For simplicity, identical parts have been given the same reference numbers. As is clear from this illustration, the fan casing 6
The section of the combustion air duct 9 which is formed on the rear side of the casing bottom 7 as a double bottom 27 of the casing bottom 7 in the flow direction, the first section of which corresponds to the width of the inlet of the casing bottom 7 in the flow direction It is gradually spreading in. By widening, the combustion air duct projects tangentially from the surface covered by the casing bottom 7, with the flat inner wall 28 extending linearly with the air filter casing.

The bent portion 32 of the passage wall 8 is connected to the combustion air duct 9
Is greatly increased, and is as close as possible to the crankcase when the fan casing 6 is fitted on the crankshaft of the internal combustion engine. The bend 32 extends in the duct wall 8 substantially parallel to the cylinder axis of the internal combustion engine. Due to the large area of the inlet (FIG. 2) in the casing bottom 7, a much larger flow enters the combustion air duct from the recirculation chamber 10 of the fan rotor 5. This reflux chamber is defined by a casing bottom 7. Reflux chamber 10
, The centrifugal acceleration of the fresh air sucked by the fan rotor, so that only contaminant-free air can reach the area of the inlet 11 of the casing bottom 7.

[Brief description of the drawings]

FIG. 1 is a schematic view of a chainsaw.

FIG. 2 is a perspective view of a structural group consisting of a fan casing having a combustion air duct.

FIG. 3 is a perspective view showing a rear side of a fan casing to which a combustion air duct is connected.

[Explanation of symbols]

 2 Internal combustion engine 4 Crankshaft 5 Fan rotor 6 Fan casing 7 Casing bottom 8 Duct wall 9 Combustion air passage 10 Space 11 Inlet 12 Peripheral wall 15 Rotation direction 17 Equipment casing 18 Air filter 19 Air filter case 24 End of inlet 25 After inlet End 27 Bottom 28 End wall 30 End face 34 Projection 41 Tool (saw chain)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Axel Klimek Germany 71409 Schweigheim Seitenstrasse 32

Claims (10)

[Claims] An internal combustion engine (2) disposed in an equipment casing (17), the crankshaft (4) of which drives a tool (41) and a fan rotor (6),
The fan rotor is disposed in a fan casing (6), inhales cooling air from an air inlet and supplies the cooling air to the internal combustion engine (2), and the combustion air is formed in a radial direction with respect to the crankshaft (4). From the inlet (11) provided in the bottom (7), which is covered by the fan rotor (5), a space (30) defined by the casing bottom (7) and the bladed end face (30) of the fan rotor (5) ( 10) In a manually operated work implement which is discharged axially through 10) and can be supplied to an air filter (18) via a combustion air duct (9), the combustion air duct (9) comprises a fan rotor (5).
Branching from the fan casing (6) in a direction substantially tangential to the rotation direction (15) of the fan, extending straight to the air filter (18), and the inlet area of the combustion air duct (9) has a casing bottom (7) and a fan A work implement characterized by being defined as a double bottom (27) of the casing (6) by a casing bottom (7) and an overlapping duct wall (8). 2. The air filter (18), wherein the cross section of the passage of the combustion air duct (9) extends continuously in the flow direction.
Work implement according to claim 1, characterized in that the outlet cross section of the combustion air duct (9) adjacent to is approximately 4 to 6 times the inlet cross section. 3. An inlet (11) provided at the casing bottom (7) extends in an arc in the direction of rotation (15) of the fan rotor (5), and a front end (25) of the inlet (11) is connected to a crankshaft. (4) The working equipment according to claim 1 or 2, wherein the working equipment is provided adjacent to an end face of an end wall (28) of the combustion air duct (9) formed nearer. 4. The work implement according to claim 1, wherein the combustion air duct has a substantially rectangular cross section. 5. The rotation direction (15) of the fan rotor (5).
The end (24) of the entrance (11) located on the near side in
The work implement according to any of the preceding claims, characterized in that is arranged on the side of the crankshaft (4) opposite to the internal combustion engine (2). 6. A fan rotor (5) in axial direction with a duct wall (8) beyond the plane of the casing bottom (7).
And a peripheral wall (12) of the fan casing (6) that overlaps with the peripheral wall (12).
5. The work equipment according to any one of the items 5. 7. Work implement according to claim 2, wherein the combustion air duct (9) is enlarged in the direction of flow parallel to the casing bottom (7). 8. A projection (34) of the combustion air duct (9) protrudes axially from the casing bottom (7) in the fan casing (6), the end face of which projects in particular with respect to the plane of the casing bottom (7). The working equipment according to any one of claims 1 to 7, wherein the working equipment is positioned in parallel with each other. 9. A crankshaft (4) in which the combustion air duct (9) extends in the region of the end (24) on the near side of the inlet (11).
And the distance between the casing bottom (7) and the double bottom (27) is such that the clearance of the crankcase of the internal combustion engine (2) adjacent to the casing bottom (7) at the installation position of the fan casing (6). 2. The method according to claim 1, wherein the angle is increased from a rectangular portion which can be set according to the volume.
8. The working device according to any one of 8 above. 10. The capacity of an air filter case (19) provided with an air filter (18) is at least five times the stroke volume of the internal combustion engine (2).
The working device according to any one of claims 9 to 9.