HANDHELD WORK APPARATUS AND DEFLECTION BOWL FOR ITS COMBUSTION ENGINE
20240125293 ยท 2024-04-18
Inventors
Cpc classification
F02M35/10262
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
B25F5/00
PERFORMING OPERATIONS; TRANSPORTING
F02M35/02483
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
International classification
F02M35/024
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
B25F5/00
PERFORMING OPERATIONS; TRANSPORTING
Abstract
A handheld work apparatus has a combustion engine and a rest position. The engine includes a cylinder wherein a piston is mounted to drive a crankshaft in a crankcase. The engine has an intake channel having an intake channel section formed in a fuel supply. The intake channel is divided into a mixture channel and an air channel. The engine has an air filter defining a clean chamber for a deflection bowl. The deflection bowl has a first passage opening whereat the air channel passes from the deflection bowl into the clean chamber and a second passage opening whereat the mixture channel passes from the deflection bowl into the clean chamber. The air channel and the mixture channel run mutually separate in the deflection bowl. In the rest position, no second passage opening extends into a region situated lower in terms of the geodetic height than the main fuel opening.
Claims
1. A handheld work apparatus comprising: a work tool; a combustion engine for driving said work tool; said handheld work apparatus defining a rest position wherein said work apparatus stands on a planar, horizontal rest surface; said combustion engine including a cylinder and a piston arranged in said cylinder so as to move in a reciprocating manner therein; said cylinder and said piston conjointly delimiting a combustion chamber formed in said cylinder; a crankcase connected to said cylinder; a crankshaft rotatably mounted in said crankcase and being operatively connected to said piston so as to permit said piston to rotatably drive said crankshaft; a fuel supply; an intake channel having an intake channel section formed in said fuel supply; a main fuel opening into said intake channel section; said intake channel having a partition wall dividing said intake channel into a mixture channel and an air channel; an air filter configured as a round air filter defining a clean chamber; an impact absorber formed in said clean chamber; said impact absorber having at least one first passage opening whereat said air channel passes from said impact absorber into said clean chamber; said impact absorber having at least one second passage opening whereat said mixture channel passes out of said impact absorber into said clean chamber; said air channel and said mixture channel being guided in said impact absorber so as to be completely separate from each other; in said rest position, said at least one second passage opening does not extend into a region situated lower with respect to the geodetic elevation than said main fuel opening; and, in said rest position, said mixture channel runs at least partly beneath said air channel at least in said fuel supply unit.
2. The handheld work apparatus of claim 1, wherein said fuel supply has an upstream end face; and, in said rest position, said at least one second passage opening does not extend into a region situated lower in terms of said geodetic elevation than said partition wall in said upstream end face.
3. The handheld work apparatus of claim 1, further comprising two of said second passage openings; and, wherein said mixture channel is divided, in said impact absorber, into two arms opening at corresponding ones of the two second passage openings.
4. The handheld work apparatus of claim 3, wherein said cylinder defines a cylinder longitudinal axis; and, said two second passage openings are arranged on respective sides of a central plane containing said longitudinal axis.
5. The handheld work apparatus of claim 1, wherein said intake channel defines a longitudinal axis; said mixture channel has a connecting opening into said impact absorber; and, said connecting opening lies entirely in overlapment with said impact absorber viewed in a direction of said longitudinal axis of said intake channel.
6. The handheld work apparatus of claim 1, wherein said impact absorber comprises a first impact absorber part and a second impact absorber part which adjoin said mixture channel.
7. The handheld work apparatus of claim 6, wherein said impact absorber has a base and said intake channel defines a longitudinal axis; and, said first impact absorber part and said second impact absorber part overlap at least on said base of said impact absorber and delimiting said impact absorber downwardly at said base in said rest position, in radial direction of said longitudinal axis of said intake channel.
8. The handheld work apparatus of claim 1, wherein said partition wall extends into said impact absorber.
9. The handheld work apparatus of claim 8, wherein a section of said partition wall is formed on the impact absorber.
10. The handheld work apparatus of claim 8, wherein said partition wall defines a central plane; and, said partition wall adjoins a rear wall of said impact absorber defining an angle (a) lying in a range of 100? to 170? with said central plane of said partition wall.
11. The handheld work apparatus of claim 1, wherein said partition wall defines a central plane; said impact absorber includes two fastening openings for respective fastening screws; and, said two fastening openings are arranged on opposite sides of said central plane of said partition wall.
12. The handheld work apparatus of claim 11, wherein said mixture channel in said impact absorber is divided into two arms having a partition wall running therebetween; and, said partition wall between said two arms adjoining said partition wall between said two fastening openings.
13. The handheld work apparatus of claim 12, wherein said partition wall between said two arms is at an angle (?) of less than 80? with the central plane of said partition wall between said two fastening openings.
14. The handheld work apparatus of claim 11, wherein at least one of said fastening openings is formed on a screw eyelet which is adjoined by a sleeve and at least one section of said sleeve is cut out for the passage of said mixture channel.
15. The handheld work apparatus of claim 1, wherein a cover is arranged in said impact absorber at least at one of said passage openings partly covering said at least one passage opening in an upward direction in said rest position.
16. The handheld work apparatus of claim 1, further comprising a cover arranged in said impact absorber at least at one of said passage openings lying lower than the other one of said passage openings in the rest position, partly covering said one passage opening in the upward direction in said rest position.
17. The handheld work apparatus of claim 1, wherein said crankcase delimits a crankcase interior; said combustion engine is a two-stroke engine having at least one transfer channel connecting said crankcase interior in the region of bottom dead center of said piston fluidically to said combustion chamber; and, said air channel is connected fluidically to said transfer channel for at least a portion of a stroke of said piston.
18. An impact absorber for arrangement in a clean chamber of an air filter of a combustion engine of a handheld work apparatus, the handheld work apparatus including: a work tool; a combustion engine for driving said work tool; said handheld work apparatus defining a rest position wherein said work apparatus stands on a planar, horizontal rest surface; said combustion engine including a cylinder and a piston arranged in said cylinder so as to move in a reciprocating manner therein; said cylinder and said piston conjointly delimiting a combustion chamber formed in said cylinder; a crankcase connected to said cylinder; a crankshaft rotatably mounted in said crankcase and being operatively connected to said piston so as to permit said piston to rotatably drive said crankshaft; a fuel supply; an intake channel having an intake channel section formed in said fuel supply; a main fuel opening into said intake channel section; said intake channel having a partition wall dividing said intake channel into a mixture channel and an air channel; said air filter being configured as a round air filter defining said clean chamber; the impact absorber comprising: said impact absorber being configured to be arranged in said clean chamber; said impact absorber having at least one first passage opening whereat said air channel passes from said impact absorber into said clean chamber; and, said impact absorber having at least one second passage opening whereat said mixture channel passes out of said impact absorber into said clean chamber.
Description
BRIEF DESCRIPTION OF DRAWINGS
[0021] The invention will now be described with reference to the drawings wherein:
[0022]
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DETAILED DESCRIPTION
[0032]
[0033] The combustion engine 1 includes a cylinder 2, in which a combustion chamber 3 is formed. In the cylinder 2, a piston 5 is mounted in a reciprocating manner between a bottom dead center BDC and a top dead center TDC. In
[0034] The combustion engine 1 includes a crankcase 4, in which a crankcase interior 9 is formed. In the crankcase 4, a crankshaft 7 is mounted rotatably about a rotational axis 8. The piston 5 drives the crankshaft 7 via a connecting rod 6 in rotation about the rotational axis 8. The crankcase interior 9 and the combustion chamber 3 are connected to the combustion chamber 3 in the region of the bottom dead center BDC of the piston 5 by transfer channels 12. The transfer channels 12 emerge by transfer windows 13 in the combustion chamber 3. The transfer windows 13 are controlled by the piston 5. An air channel 19 having at least one air inlet 11 emerges at the cylinder 2. A mixture channel 18 emerges by a mixture inlet 10 at the cylinder 2. An outlet 15 leads out from the combustion chamber 3. The outlet 15, the mixture inlet 10, and the air inlet 11 are controlled by the piston 5. The piston 5 includes one or more piston pockets 14. The piston pocket 14 connects the air inlet 19 to the transfer windows 13 in the region of the top dead center TDC of the piston 5. The representation in
[0035] The combustion engine 1 during operation draws air in through an intake channel 16. The intake channel 16 is divided by a partition wall 17 into the air channel 19 and the mixture channel 18. One section of the intake channel 16 is formed in the fuel supply unit 20. In the embodiment, the fuel supply unit 20 is a carburetor. However, a different kind of fuel supply unit, such as a fuel valve, can be advantageous. In the intake channel 16, in the embodiment in the fuel supply unit 20, there is pivot-mounted a throttle element 24 for controlling the free flow cross section of the intake channel 16. For this, the throttle element 24 has a throttle shaft 84. In the embodiment, upstream from the throttle element 24 there is arranged a choke element 25. The choke element 25 can likewise be pivot-mounted in the intake channel 16. In the embodiment, the choke element 25 is pivot-mounted with a choke shaft 85.
[0036] The fuel supply unit 20 includes a base body 21, in which an intake channel section 22 of the intake channel 16 is formed. In the embodiment, a partition wall section 26 extends between the choke shaft 85 and the throttle shaft 84. The partition wall section 26 can be formed on the base body 21 or it can be held on the latter. A section 49 of the partition wall 17 extends upstream from the choke shaft 85. The section 49 of the partition wall 17 in the embodiment is formed on a deflection bowl 40. In the deflection bowl 40, a section 78 of the mixture channel and a section 79 of the air channel are situated. The sections 78 and 79 run entirely separate from each other in the deflection bowl 40.
[0037] The terms upstream and downstream in the present instance refer to a flow direction 60 in the intake channel directed from the fuel supply unit 20 to the cylinder 2 or to the crankcase 4 of the combustion engine 1.
[0038] Upstream from the fuel supply unit 20 there is arranged an air filter 37, by which the combustion engine 1 draws in combustion air. The air filter 37 includes filter material 39 which separates a clean chamber 38 of the air filter 37 from the surroundings. The air filter 37 is configured as a round filter and it includes a base plate 70 as well as a cover plate 71. The base plate 70 and the cover plate 71 advantageously run parallel to each other. The filter material 39 extends between the base plate 70 and the cover plate 71, being formed preferably of plastic such as PET and being arranged folded in particular. The deflection bowl 40 is surrounded by the filter material 39. The deflection bowl 40 adjoins the base plate 70. In the embodiment, the deflection bowl 40 is arranged tightly in an opening 88 (also see
[0039] The fuel supply unit 20 includes a main fuel opening 23, through which mixture is drawn into the mixture channel 18 during operation. Further fuel openings may be present, in particular idling fuel openings and/or partial load fuel openings. The main fuel opening 23 emerges upstream from the throttle shaft 84 in the mixture channel 18. Because of pulsations in the intake channel 26, mixture can flow contrary to the flow direction 60 toward the deflection bowl 40 during operation. The deflection bowl 40 is configured to prevent fuel from getting into the clean chamber 38 of the air filter 37 and fouling the filter material 39. The configuration of the deflection bowl 40 provided for this shall be described in more detail in the following.
[0040] The intake channel 26 has an intake channel longitudinal axis 29. The main fuel opening 23 emerges in the region of a Venturi section 30 in the mixture channel 18. The partition wall 17 has a central plane 36, containing the intake channel longitudinal axis 29.
[0041] The fuel supply unit 20 has an upstream situated end face 33 and a downstream situated end face 34. At the upstream situated end face 33, the fuel supply unit 20 has a connecting opening 28, at which the mixture channel 18 stands in communication with the section 78 of the mixture channel 18 formed in the deflection bowl. The upstream situated end face 33 of the fuel supply unit 20 furthermore has a connecting opening 31, at which the section 79 of the air channel 19 formed in the deflection bowl passes into the section of the air channel 19 formed in the fuel supply unit 20. The connecting openings 28 and 31 form a connecting opening 50 at the end face 33, where the intake channel 16 passes from the deflection bowl 40 into the fuel supply unit 20. At the end face 33, the section 49 of the partition wall 17 protrudes into the connecting opening 50 and divides this into the connecting openings 28 and 31.
[0042] At the upstream situated end face 33, the fuel supply unit 20 includes a compensation connection 90, by which the pressure from the clean chamber 38 of the air filter 37 is provided as a reference pressure. This is provided in particular when the fuel supply unit 20 is configured as a membrane carburetor. The deflection bowl 40 has an opening 89 to the clean chamber 38 of the air filter 37, to which the compensation connection 90 is attached.
[0043] In operation, the combustion engine 1 during the upward stroke of the piston 5 draws the fuel/air mixture from the mixture channel 18 into the crankcase interior 9. Once the air inlet 11 is connected via the piston pocket 14 to transfer windows 13, air is drawn from the air channel 19 through the piston pocket 14 into the transfer channels 12, and this is because of the partial vacuum prevailing in the crankcase interior 9. Fuel/air mixture from the previous motor cycle which is still present in the transfer channels 12 is displaced in the direction of the crankcase interior 9. During the downward stroke of the piston 5, at first the outlet 15 is opened and exhaust gases from the previous motor cycle flow out. After this, air from the transfer channels 12 flows via the transfer window 13 into the combustion chamber 3 and purges exhaust gases which are still present from the previous motor cycle in the combustion chamber 3, through the outlet 15. Next, fresh fuel/air mixture from the crankcase interior 9 flows via the transfer channels 12 into the combustion chamber 3. During the upward stroke of the piston 5, the mixture in the combustion chamber 3 is compressed and ignited in the usual manner in the region of the top dead center TDC of the piston 5 by a spark plug 32 protruding into the combustion chamber 3. In the subsequent combustion, the piston 5 is accelerated in the direction of the crankcase 4. Once the outlet 15 opens, the exhaust gases flow out from the combustion chamber 3 and stratified scavenging air and fresh fuel/air mixture for the following motor cycle flow into the combustion chamber 3.
[0044]
[0045] The work apparatus 51 includes a housing 52, on which a rear handle 53 and a bale handle 54 are fastened, preferably via antivibration elements. The work apparatus 51 can be guided by the user during operation by means of the handle 53 and the bale handle 54.
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[0048] Advantageously, the passage openings 41 and 42 of the deflection bowl 40 have a spacing b from the cover plate 71, as shown in
[0049] As shown by
[0050] As
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[0052] The section 79 of the air channel 19 emerges, as shown by
[0053] As shown by
[0054] As shown by
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[0060] As shown by
[0061] In
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[0063] It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.