DE10362394B3 - carburetor arrangement - Google Patents

Abstract

Carburettor arrangement, in particular for the two-stroke engine in a hand-held working apparatus such as a power saw, a cut-off machine or the like, with an intake duct (22) which is divided by a partition (11) into an air duct (8) and into a mixture duct (21), wherein a fuel port (27, 28) for supplying fuel to an internal combustion engine flows into the mixture passage (21) and a carburetor (17) having a carburetor body (18) in which an intake passage portion (32) is formed and in which a throttle flap (24) is pivotally mounted, wherein the carburetor housing (18) has an upstream end face (33), characterized in that a partition wall portion (31, 48, 58, 68, 78, 88, 98) upstream of the throttle valve (24 ) is formed as a separate component, which is held in the intake passage (22), that the partition wall portion (48, 68, 78, 88) on the upstream end face (33) extends beyond the carburetor housing (18) and that the partition wall section (88) is designed to be angled away from the intake duct longitudinal axis (43) in a section (85, 86) projecting beyond the end face (33) of the carburettor (17).

Description

The invention relates to a carburetor, in particular for the two-stroke engine in a hand-held implement such as a power saw, a power grinder or the like. Specified in the preamble of claim 1 genus.

From the DE 101 60 539 A1 a carburetor assembly for a two-stroke engine is known in which the intake passage is divided with a partition in a mixture channel and in an air duct. The partition extends both downstream and upstream of the throttle valve pivotally mounted in the carburetor.

The JP S61-182 452 A shows an intake device with a roll carburetor. Downstream of the roller gasifier a partition wall section is inserted at the transition between two Ansaugkanalabschnitten, which carries a damping material on its longitudinal sides. This is to achieve a vibration-proof arrangement. The partition section may be arranged off-center in the intake passage. The partition portion may also have a T-shaped cross section and divide the intake passage into three channels.

The EP 1 078 151 B1 shows a two-stroke engine whose intake is divided downstream of the carburetor in two and then in three sub-channels. The throttle valve is located in a ring in the intake passage. Upstream of the throttle valve there is no further separation of the intake duct in the air duct and the mixture duct. The partition is designed as a thin wall.

The invention has for its object to provide a carburetor of the generic type, which is simple and easy to manufacture.

Due to the design of the partition wall section as a separate component this can be made independently of the carburetor housing. The geometry of the partition can be chosen freely because the shape is not limited by the Entformungsrichtung of the carburetor. In order to achieve a good separation of the air channel from the mixture channel, it is provided that the partition wall section extends beyond the carburetor housing on the upstream end side. The partition wall section is formed in an over the front side of the carburetor protruding portion opposite the Ansaugkanallängsachse angled.

Advantageously, the partition wall section is angled in a first section to the mixture channel. In a second section of the partition wall portion is angled in particular to the air duct. The angling of the partition wall portion to the air duct leads to the fact that the air duct sucks air from a region facing away from the mixture channel. Due to the engine pulsations, during operation of the internal combustion engine, the fuel also passes through the mixture channel into an area upstream of the carburettor, in particular into an air filter. There, the fuel forms a fuel mist, which can be sucked into the air duct. By bending the partition wall in the direction of the air duct, the air duct sucks in the air from a region facing away from the mixture channel, so that it is possible to prevent the mixture from entering the air duct.

A simple attachment of the partition wall in the intake passage can be achieved in that the partition wall section is guided in a groove which is parallel to the Ansaugkanallängsachse. The groove can be made in the manufacture of the carburetor housing in the same manufacturing step with. By arranging the groove parallel to the intake duct longitudinal axis of the partition wall portion can be inserted in the direction of the intake passage longitudinal axis in the intake passage in the carburetor housing. Through the groove, the partition is securely held without the need for additional fasteners. It is envisaged that the groove is bounded by at least one longitudinal web projecting into the intake passage. The groove bottom expediently ends flush with the intake duct wall. However, it may also be expedient that the groove is formed as a recess in the intake passage wall. As a result, the flow cross section in the intake passage is not impaired by the support of the partition wall section. However, it may also be advantageous that the groove bottom is raised in relation to the intake channel wall.

For fixing the partition wall section in the intake passage is provided that the partition wall section has a stop which determines the position of the partition wall section in the intake passage. Advantageously, the stop on the upstream end face of the carburetor housing on the carburetor housing. The partition wall can thereby be inserted from the upstream end face in the intake passage. The partition wall can be inserted after the assembly of the throttle and the throttle shaft. As a result, the accessibility in the assembly of the throttle valve on the throttle shaft, which is usually fastened with a screw, improved. The assembly is simplified. However, it may also be expedient that a shoulder is formed on the groove on the side facing the throttle shaft, against which the stop abuts. The partition can then be inserted from the downstream side of the carburetor housing in the intake passage and is fixed by the subsequently mounted throttle shaft in the intake passage. Appropriately has the Carburetor housing a bearing bore through which the throttle shaft protrudes. The bearing bore extends advantageously from the intake to the outside of the housing. It is envisaged that the groove extends from the upstream end face of the carburetor housing to the bearing bore of the throttle shaft. In particular, the groove extends over the entire length of the carburetor housing. A recess formed as a groove can thereby be produced in a simple manner. In order to avoid that the storage of the throttle shaft is affected by the groove, it is provided that the throttle shaft is mounted in a bearing bush arranged in the bearing bore and abuts the partition wall on the bearing bush. The bearing bush thus simultaneously forms a stop which limits the insertion depth of the partition in the intake passage.

In order to achieve a good separation of the air channel from the mixture channel upstream of the throttle valve, it is provided that the partition wall portion has an edge against which the throttle valve in the open position. The partition wall section advantageously extends to the throttle shaft. This results in the opening position of the throttle, a high coverage of the partition wall portion with the throttle. As a result, the mixture channel can be separated from the air duct largely dense. Advantageously, a projection is arranged on the partition, which projects into the mixture channel and reduces the flow cross-section in the mixture channel. Such a reduction of the flow cross-section serves to match the ratio of supplied air and supplied mixture to one another. The projection can be easily formed on the partition wall.

Appropriately, the groove in which the partition is guided, to the axis of rotation of the throttle shaft at a distance. In this case, the throttle shaft is offset in particular with respect to the groove, so that an impairment of the leadership of the throttle shaft is avoided by the groove.

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

1 a schematic sectional view of an internal combustion engine with a carburetor,

2 3 is a perspective view of a carburettor not shown according to the invention with partially inserted dividing wall section;

3 a side view of the carburetor not according to the invention 2 .

4 a perspective view of a shown cut, not inventive carburetor and a partition wall section in an exploded view,

5 a side view of the carburetor not according to the invention 4 .

6 7 is an exploded view of a carburettor not shown in the drawing,

7 a side view of the carburetor not according to the invention 6 .

8th 3 is a perspective view of a carburettor not shown in the drawing,

9 a side view of the carburetor not according to the invention 8th .

10 a perspective view of the sleeve with the partition from 9 .

11 a cut shown inventive carburetor in perspective,

12 a perspective view of the partition of the carburetor 11 .

13 a side view of the partition off 12 .

14 a schematic longitudinal section through a carburetor not according to the invention.

The in 1 shown two-stroke engine 1 has one in a cylinder 2 trained combustion chamber 3 that of a piston 5 is limited. The piston 5 is in the cylinder 2 stored back and forth and drives over a connecting rod 6 one in a crankcase 4 mounted crankshaft 7 at. At the cylinder 2 opens a mixture channel 21 with an inlet 20 and an air duct 8th with an air window 9 , The inlet 20 and the air window 9 are from the piston skirt 30 of the piston 5 slot-controlled. At the in 1 shown position of the piston 5 at bottom dead center is the crankcase 4 via two overflow channels 12 . 15 with the combustion chamber 3 connected. The overflow channels 15 open with overflow windows 13 and 16 in the combustion chamber 3 , About the overflow channels 12 and 15 flows fuel / air mixture from the crankcase 4 in the combustion chamber 3 , The piston 5 has a piston bag 14 holding the air window 9 in predetermined positions of the piston 5 with the overflow windows 13 and 16 the overflow channels 12 and 15 combines.

In operation of the two-stroke engine 1 flows in at the 1 shown position of the piston 5 at bottom dead center fuel / air mixture from the crankcase 4 over the overflow channels 12 and 15 in the combustion chamber 3 , During the upstroke of the piston 5 becomes the fuel / air mixture in the combustion chamber 3 compacted. During the upstroke of the piston 5 becomes the air window 9 over the piston bag 14 with the overflow windows 13 and 16 connected. From the air duct 8th flows largely fuel-free air into the transfer channels 12 and 15 and displaces the mixture in the transfer ports towards the crankcase 4 , In the area of top dead center of the piston 5 becomes the fuel / air mixture in the combustion chamber 3 ignites and accelerates the piston in the direction of the crankcase 4 , During the downward stroke of the piston 5 becomes the outlet 10 from the combustion chamber 3 released and the exhaust gases leave the combustion chamber 3 through the outlet 10 , Once the overflow window 13 and 16 from the piston 5 be released flows in the overflow channels 12 and 15 upstream air and then fuel / air mixture from the crankcase 4 in the combustion chamber 3 , The upstream air in the overflow channels causes a separation of the exhaust gases from the fuel / air mixture and prevents fresh fuel through the outlet 10 can escape.

The air duct 8th and the mixture channel 21 are in a suction channel 22 formed by a partition 11 in the air duct 8th and the mixture channel 21 is disconnected. To form the fuel / air mixture is a carburetor 17 provided in which a Ansaugkanalabschnitt 32 is trained. The carburetor 17 has a carburetor housing 18 in which a throttle 24 with a throttle shaft 25 is pivotally mounted. Upstream of the throttle 24 is a venturi in the carburetor 23 educated. In the mixture channel 21 open idling nozzles 27 as well as in the area of the Venturi 23 a main fuel nozzle 28 ,

Upstream of the throttle 24 is a partition wall section 31 arranged, the air duct 8th from the mixture channel 21 related to the flow direction 26 upstream of the throttle 24 separates. Upstream of the carburetor 17 is an air filter 41 arranged at the air filter bottom 40 the carburetor 17 is arranged. The partition section 31 can get into the air filter 41 extend into it. The partition 11 thus extends over the entire, parallel to the Ansaugkanallängsachse 43 measured length l of the carburetor body 18 ,

In opening position of the throttle valve 24 this is approximately parallel to the Ansaugkanallängsachse 43 in the intake channel 22 , At the partition wall section 31 and at the throttle 24 facing section of the partition 11 is each an edge 35 trained with a seal 37 is provided. On the edge 35 is the flap edge 36 the throttle 24 on, leaving the throttle 24 with the partition 11 sealing and closes the air duct 8th completely from the mixture channel 21 separates. At the in 1 shown slightly open position of the throttle 24 are between the throttle 24 and the partition 11 both upstream and downstream of the throttle 24 connecting ports 34 formed over which the air duct 8th with the mixture channel 21 connected is. This allows the negative pressure in the air duct 8th at low load of the two-stroke engine 1 be compensated. In the air filter 41 is a filter element 42 arranged, which is connected to the surrounding raw air side of the air filter 41 from the one with the intake duct 22 connected clean side separates. To the carburetor 17 to be able to produce in a simple manner, is the partition wall section 31 upstream of the throttle 24 designed as a separate component. The partition section 31 is in the intake channel 22 in the direction of the intake duct longitudinal axis 43 plugged in.

2 shows a carburetor not according to the invention 17 with an inserted partition section 48 , In the carburetor housing 18 is the intake passage section 32 trained and the throttle 24 with the throttle shaft 25 pivoted. Upstream of the throttle 24 is the intake channel 22 from a partition wall section 48 in an air duct 8th and a mixture channel 21 separated. The partition section 48 is designed as a separate component and in a groove 29 in the intake channel 22 guided. The groove 29 runs parallel to the in 1 shown intake duct longitudinal axis 43 , The intake duct longitudinal axis 43 runs in the flow direction 26 and connects the geometric centers in each flow area. The partition section 48 is from the upstream end face 33 of the carburetor 17 in the intake channel 22 pluggable. In 2 is the partition wall section 22 in the groove 29 half inserted. The partition section 48 owns a stop 47 extending laterally to the partition wall section 48 in through the partition wall section 48 extending level formed. When fully in the intake 23 inserted partition wall section 48 is the stop 47 at the front 33 of the carburetor body 18 at. In the mixture channel 21 opens a fuel nozzle 28 which may be powered by a fuel metering system. The fuel nozzle 28 can also be downstream of the throttle 24 in the mixture channel 21 lead. The carburetor 17 However, it can also be designed as a membrane carburetor and in the region of the fuel nozzle 28 a Venturi section can be formed.

As well as 3 shows is the mixture channel wall section 44 upstream of the throttle 24 in the intake channel 22 put into it, so that the flow cross-section in the mixture channel 21 is reduced. The mixture channel wall section 44 forms to the canal wall 45 in the area of the throttle 24 a paragraph 39 , At the air duct 8th facing side is the groove 29 from a longitudinal ridge 19 limited. On the the mixture channel 21 facing side of the partition wall section 48 on a heel 38 at the mixture channel wall section 44 at. The mixture channel wall section 44 thus limits the groove 29 on the mixture channel 21 facing side. The groove bottom 46 just goes into the intake duct wall 45 above. In the area of the throttle 24 has the partition section 48 a border 49 at which the throttle 24 in the in 2 shown opening position 52 with fully inserted partition wall section 48 is applied. At the edge 49 is a semi-circular recess 50 attached, in the area of a fastening screw, not shown, with the throttle 24 at the throttle shaft 25 is fixed is arranged.

4 shows another carburetor not according to the invention 17 , In the carburetor housing 18 formed intake passage section 32 is a groove 59 formed parallel to the in 1 shown intake duct longitudinal axis 43 runs. As well as 5 shows is the groove bottom 56 opposite the intake duct wall 45 formed sublime and protrudes into the intake 22 , It is a partition wall section 58 provided by the throttle shaft 25 facing side into the groove 59 can be inserted. At the throttle shaft 25 facing side has the partition wall section 58 a stop 57 , When completely in the groove 59 inserted partition section 58 is the stop 57 on a heel 55 at between a mixture channel wall section 53 and the intake passage wall 45 is formed. The mixture channel wall section 53 is the mixture channel 21 limiting wall section upstream of the throttle shaft 24 and is how 5 shows in the intake 22 put into it and causes a reduction of the flow cross-section in the mixture channel 21 , The two oppositely arranged grooves 59 are at the air duct 8th facing side of longitudinal webs 54 limited and at the opposite, the mixture channel 21 facing side of the mixture channel wall portion 53 , As 4 shows, has the carburetor body 18 a bearing bore 51 in which the throttle shaft 25 after the complete insertion of the partition wall section 58 into the grooves 59 is stored. The throttle shaft 25 then fixes the partition wall section 58 in the intake channel 22 , The partition section 40 owns at the throttle 24 facing side an edge 49 at which the throttle 24 in the open position and a recess 50 for a fixing screw of the throttle valve 24 ,

The 6 and 7 show another carburetor not according to the invention 17 , The carburetor housing 18 the carburetor not according to the invention 17 has opposite grooves 69 , which are called depressions in the intake duct wall 45 are formed and extending over the entire length l of the carburetor housing 18 extend. The grooves 69 thereby cut the bearing bore 65 for the throttle shaft 25 , In the bearing bore 65 is a bearing bush 64 arranged in which the throttle shaft 25 is stored. The bearing bush 64 closes the groove with it 69 at the throttle shaft 25 facing side. For separation of air duct 8th and mixture channel 21 upstream of the throttle shaft 25 is a partition wall section 68 intended. The partition section 68 owns at the throttle shaft 25 facing side a recess 70 in which the bearing bush 64 is arranged. The bearing bush 64 and the recess 70 can be a stop for the partition wall section 68 form. However, it can also or in addition to in 6 shown stop 67 be provided, extending from the partition wall section 68 to the intake duct longitudinal axis 43 extends radially outwards and at the front side 33 of the carburetor body 18 is applied. Also the partition wall section 68 has a border 49 with a recess 50 , where the throttle 24 in open position 52 on the edge 49 is applied. As 7 shows is the groove bottom 66 as a depression in the intake duct wall 45 formed and opposite the intake duct wall 45 to the intake duct longitudinal axis 43 offset radially outwards.

The 8th to 10 show a further embodiment of a carburetor not according to the invention 17 , Upstream of the throttle 24 is a sleeve 76 in the carburetor housing 18 arranged in which a Ansaugkanalabschnitt 74 is trained. The inner diameter of the sleeve 76 is smaller than that of the intake duct 22 and the outer diameter of the sleeve 76 is bigger. Between in the carburetor housing 18 trained intake duct wall 75 and the upstream of the throttle 24 formed section is a paragraph 79 formed, on which the sleeve 76 with its downstream end face 81 over its entire circumference. The sleeve 76 has a partition wall section 78 that is integral with the sleeve 76 is trained. The partition section 78 owns a stop 77 standing at the front 33 of the carburetor body 18 is applied and the depth of insertion of the sleeve 76 into the carburetor housing 18 limited. The upstream end face 80 the sleeve 76 closes flush with the front 33 of the carburetor body 18 from. The fuel nozzle 28 protrudes from the carburetor housing 18 through the sleeve 76 , At the throttle 24 facing side has the partition wall section 78 a border 49 with a recess 50 at which the throttle 24 in the in 8th shown opening position 52 is applied.

As 9 shows has the partition wall section 78 two attacks 77 which are arranged diametrically opposite each other. In 10 is the partition wall section 78 with the sleeve 76 shown in perspective. The partition section 78 protrudes at both ends 80 . 81 over the sleeve 76 out.

In 11 is an inventive carburetor 17 shown. In the carburetor housing 18 is a partition wall section 88 from the upstream end face 33 out into the intake duct 22 inserted. The partition section 88 is at its longitudinal sides in two in the longitudinal direction of the intake passage 22 running grooves, the longitudinal webs 19 are limited. The mixture channel wall section 53 upstream of the throttle 24 is opposite the intake duct wall 45 in the intake channel 22 put into it, so that a reduced flow cross-section in the mixture channel 21 upstream of the throttle 24 results. In addition, at the partition wall section 88 a lead 89 molded, located in the mixture channel 21 extends and the flow cross-section in the mixture channel 21 at the height of the fuel nozzle 28 additionally reduced. The partition section 88 is over the front 33 out into an upstream of the carburetor 17 arranged air filter 41 ( 1 ) extended. In particular 12 and 13 show the partition wall section 88 a first angled section 85 pointing towards the mixture channel 21 opposite the intake duct longitudinal axis 43 is angled. At the first angled section 85 closes a second angled section 86 on the air duct 8th facing side is angled. The second angled section 86 closes with the intake duct longitudinal axis 43 an angle α, which is in particular greater than 45 ° and which is advantageously more than 60 °. This ensures that in the air duct 8th Air from an area of the air filter 41 is sucked in, no fuel from the mixture channel 21 is available. In the area of the first angled section 85 are at the partition wall section 88 two laterally projecting stops 87 molded, which in the intake 22 inserted partition wall section 88 at the front 33 of the carburetor body 18 issue.

In 14 , which shows a schematic longitudinal section through a carburetor not according to the invention, is schematically in the intake passage 22 inserted partition wall section 98 shown. The partition section 98 is in a groove 99 guided and divides the intake duct 22 in an air duct 8th and into a mixture channel 21 , The groove 99 of the partition wall section 98 owns to the axis of rotation 96 the throttle shaft 25 a distance a. The distance a is chosen so that the groove 99 the bearing bore of the throttle shaft 25 does not cut, leaving through the groove 99 no impairment of the bearing of the throttle shaft 25 results. The partition section 98 is in the direction of the intake duct longitudinal axis 43 formed angled and has a wall portion 95 which runs on the intake duct wall. The partition section 98 owns at the throttle 24 facing side an edge 97 at which the throttle 24 in the in 14 shown opening position 52 is applied.

Due to the pluggable design of the partition wall section, the geometry of the partition wall section can be independent of the demolding of the carburetor housing 18 be chosen without affecting the manufacturability of the carburetor 17 is worsened.

Claims (10)

Carburettor arrangement, in particular for the two-stroke engine in a hand-guided working device such as a power saw, a cut-off machine or the like, with an intake duct (FIG. 22 ) separated by a partition ( 11 ) in an air duct ( 8th ) and into a mixture channel ( 21 ), where in the mixture channel ( 21 ) a fuel port ( 27 . 28 ) for supplying fuel to an internal combustion engine and with a carburetor ( 17 ), which is a carburettor housing ( 18 ), in which an intake passage section ( 32 ) is formed and in which a throttle valve ( 24 ) is pivotally mounted, wherein the carburetor housing ( 18 ) an upstream end face ( 33 ), characterized in that a partition wall section ( 31 . 48 . 58 . 68 . 78 . 88 . 98 ) upstream of the throttle valve ( 24 ) is formed as a separate component in the intake channel ( 22 ) is held, that the partition wall section ( 48 . 68 . 78 . 88 ) on the upstream end face ( 33 ) via the carburetor housing ( 18 ) and that the partition wall section ( 88 ) in one over the front side ( 33 ) of the carburettor ( 17 ) projecting section ( 85 . 86 ) with respect to the intake duct longitudinal axis ( 43 ) is angled. Carburettor arrangement according to claim 1, characterized in that the partition wall section ( 88 ) in a section ( 85 ) to the mixture channel ( 21 ) is angled away. Carburettor arrangement according to claim 1, characterized in that the partition wall section ( 88 ) in a section ( 86 ) to the air duct ( 8th ) is angled away. Carburetor arrangement according to one of claims 1 to 3, characterized in that the partition wall section ( 31 . 48 . 58 . 68 . 78 . 88 . 98 ) in a groove ( 29 . 59 . 69 . 79 . 99 ) is guided. Carburetor arrangement according to claim 4, characterized in that the groove ( 29 . 59 ) through at least one in the intake passage ( 20 ) projecting longitudinal web ( 19 . 54 ) is limited. Carburetor arrangement according to claim 4 or 5, characterized in that the groove bottom ( 46 ) flush with an intake duct wall ( 45 ) completes. Carburetor arrangement according to claim 4 or 5, characterized in that the groove ( 69 . 99 ) as a depression in a suction channel wall ( 45 ) is trained. Carburetor arrangement according to claim 4 or 5, characterized in that the groove bottom ( 56 ) with respect to an intake duct wall ( 45 ) is formed sublime. Carburetor arrangement according to one of claims 4 to 8, characterized in that the partition wall section ( 48 . 58 . 68 . 78 . 88 ) a stop ( 47 . 57 . 67 . 77 . 87 ) having the position of the partition wall section ( 48 . 58 . 68 . 78 . 88 ) in the intake channel ( 22 ). Carburetor arrangement according to claim 9, characterized in that the stop ( 47 . 57 . 67 . 77 . 87 ) on an upstream end face ( 33 ) of the carburetor housing ( 18 ) on the carburetor housing ( 18 ) is present.

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