Membrane carburetor arrangement in a work apparatus having an internal combustion engine

Information

  • Patent Grant
  • 6536395
  • Patent Number
    6,536,395
  • Date Filed
    Thursday, September 28, 2000
    23 years ago
  • Date Issued
    Tuesday, March 25, 2003
    21 years ago
Abstract
The invention is directed to a carburetor arrangement in a work apparatus having an internal combustion engine (2). The inlet channel (7) of the engine is connected via a connecting tube (8) to the intake channel section (9) of the membrane carburetor (4). The connecting tube (8) projects through a partition wall (3) arranged between the engine (2) and the carburetor (4). The carburetor (4) is fixed against the partition wall (3). Also, an intake air filter (70) is provided and supplies combustion air. The intake air filter is connected to the end (19) of the intake channel section (9) facing away from the partition wall (3). An attachment of the carburetor is provided without tools in that the carburetor is held clamped in the longitudinal direction of the intake channel section (9) between the partition wall (3) and a wall (22) of the air filter housing (20).
Description




BACKGROUND OF THE INVENTION




In carburetor arrangements in work apparatus such as motor-driven chain saws, blowers, brushcutters, cutoff machines or the like, the carburetor is customarily arranged in a carburetor compartment of the apparatus housing and is tightly secured with threaded fasteners by means of stud bolts on a partition wall between the carburetor and the engine.




German patent publication 3,741,018 discloses such a carburetor arrangement in a motor-driven chain saw. The end of the carburetor which faces away from the partition wall is fixed additionally with an attachment piece of sheet metal. This piece of sheet metal functions to fix the filter element of the intake air filter at the same time by means of an attachment screw. The intake air filter is connected at the end of the carburetor facing away from the partition wall to the intake channel section and is fixed tightly to the housing. A carburetor arrangement of this kind is complex and is difficult to assemble and disassemble. To disassemble the carburetor, the attachment sheet metal has to be loosened and the nuts threadably engaging the stud bolts must be removed. The stud bolts are made of metal because of the acting forces whereby a certain heat transfer from the engine to the carburetor must be accepted.




An unwanted warming of the carburetor can, however, lead to the formation of vapor bubbles in the fuel-filled chambers which, in turn, can lead to operational disturbances because of a leaning of the mixture supplied to the engine.




SUMMARY OF THE INVENTION




It is an object of the invention to provide a simple carburetor arrangement which can be assembled and disassembled essentially without work tools.




The carburetor arrangement of the invention is for a work apparatus with an internal combustion engine having an inlet channel. The carburetor arrangement includes: an apparatus housing defining a space for mounting the engine therein; a carburetor having an intake channel extending therethrough and the intake channel defining a longitudinal axis; a partition wall disposed between the engine and the carburetor and the carburetor being positioned on the partition wall; the intake channel having a first end facing toward the partition wall and a second end facing away from the partition wall; a connecting tube projecting through the partition wall to connect the inlet channel of the engine to the intake channel of the carburetor at the first end thereof; an intake air filter communicating with the second end of the carburetor for conducting combustion air thereto; an additional wall; and, means for clamping and holding the carburetor between the partition and additional walls in the direction of the longitudinal axis.




The invention is based on the basic idea to fix a carburetor, which is to be mounted on an engine, by clamping the carburetor between two walls fixed in the housing without separate attachment elements.




The carburetor is advantageously pressed against the partition wall between the engine and the carburetor in that the carburetor is loaded by an additional wall with a clamping force.




The additional wall is preferably a wall of the intake air filter housing which can be clipped on the apparatus housing without separate attaching means. For this purpose, the air filter housing is pivotally hooked into a mounting location fixed with respect to the housing and is latched fixedly to the housing via a latch connection which latches in the mounted position. In further embodiments of the invention, the latching is achieved via a tension spring or a threaded fastener connection.




The air filter housing is advantageously held in the mounted position via a pivot arm so that the mounted position can be provided fixed to the housing at a suitable location of the work apparatus independently of the mounting arrangement of the air filter housing. The latching arrangement is advantageously formed by a simple latch hook, which can engage especially behind a latch edge of the partition wall and is provided on the end of a latching arm. Latching can be provided at a suitable location within the housing via the latching arm. Furthermore, considerable clamping forces can be built up via the pivot arm and the latching arm or via the tension spring because of elastic deformation. The clamping forces ensure a secure holding of the carburetor between the partition wall and the air filter housing. For this purpose, the air filter housing, its pivot arm, and the latching arm with the latching hook are made of plastic and are especially made as one piece of plastic.




Centering means, which engage in corresponding centering openings of the carburetor, are mounted on at least one wall in order to ensure a position-correct alignment of the carburetor relative to the connecting pipe, which is held in the partition wall, as well as relative to the flow opening in the air filter housing. The centering means are advantageously provided on both walls between which the carburetor is held. It can be advantageous to provide the centering means for engaging in walls on the carburetor itself.




In a further embodiment of the invention, the carburetor is held by guide bolts on the partition wall. These guide bolts engage in bores of the carburetor. For assembly, the carburetor is threaded onto the guide bolts and is clamped by the air filter housing which is then latched onto the apparatus housing. The carburetor is then reliably held between the wall of the filter housing and the partition wall.




The guide bolts and the partition wall are preferably made as one piece from plastic to avoid a heat conduction between the engine and the carburetor.











BRIEF DESCRIPTION OF THE DRAWINGS




The invention will now be described with reference to the drawings wherein:





FIG. 1

is an exploded side elevation view showing a portion of an engine housing with an internal combustion engine as well as a carburetor arrangement;





FIG. 2

is a schematic of the embodiment shown in

FIG. 1

with a partially assembled carburetor;





FIG. 3

is a further view of the embodiment of

FIG. 1

shown with a mounted carburetor arrangement which is operationally ready;





FIG. 4

is a variation of the embodiment of

FIG. 3

wherein an air filter housing is fixed via a tension spring;





FIG. 5

is a further variation of the carburetor arrangement of the invention with a threaded fastener connection for uncovering the air filter housing; and,





FIG. 6

is another embodiment of the arrangement of the invention wherein the air filter housing is mounted on mounting bolts common with the carburetor.











DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION




The internal combustion engine


2


, which is mounted in the apparatus housing


1


, is shown in phantom outline in the embodiment of

FIGS. 1

to


3


and the additional embodiments shown in

FIGS. 4

to


6


.




Walls are provided within the apparatus housing


1


and are preferably configured as one piece with the housing. These walls partition a carburetor space


5


from the engine space


6


for accommodating the engine


2


. A partition wall


3


of this kind lies between the engine


2


and a carburetor


4


mounted in the carburetor space


5


. The partition wall


3


essentially functions to protect the carburetor


4


against the thermal influences of the engine


2


.




The intake channel section


9


of the carburetor


4


is connected via a connecting tube


8


with the inlet channel


7


of the engine in order to conduct the mixture formed in the carburetor


4


to the engine


2


. The connecting tube


8


is configured to be elastic in the embodiments shown. For this reason, a decoupling of the carburetor


4


with respect to vibration from the engine


2


is achieved.




As shown in

FIG. 1

, guide bolts


10


are provided on the side of the partition wall


3


facing toward the carburetor space


5


. The guide bolts


10


stand approximately perpendicular to a support surface


11


on which the end face


12


of the carburetor


4


comes into contact engagement. Two guide bolts


10


are provided for centering the carburetor


4


and these bolts together with a longitudinal center axis


13


of the intake channel section


9


lie in a plane. The guide bolts


10


thereby lie diametrically to the longitudinal center axis


13


on both sides of the intake channel section


9


.




As shown in

FIG. 1

, the partition wall


3


is reinforced in the region of the mounting surface


11


in order to accommodate the clamping forces which will be described hereinafter. The guide bolts


10


and the partition wall


3


are advantageously made of plastic and are especially made as one piece of plastic.




As shown in

FIG. 2

, the carburetor


4


is mounted on the guide bolts


10


. The guide bolts


10


engage in bores


14


of the carburetor


4


whereby a centering of the carburetor with respect to the connecting tube


8


is ensured. As

FIG. 2

also shows, the guide bolts


10


are made shorter than the length of the carburetor measured in the direction of the longitudinal center axis


13


. In the embodiment, the guide bolts


10


are only approximately half as long as the intake channel section


9


which passes through the carburetor


4


as shown in FIG.


1


. The bores


14


for accommodating the bolts


10


are formed in lateral flanges


15


of the carburetor


4


. In the embodiment shown, the carburetor is advantageously a membrane carburetor.




The connecting tube


8


has a flange-like expanded end


16


which is seated in an annularly-shaped receptacle


17


of the partition wall


3


. The connecting tube


8


is thus inserted from the carburetor space


5


through the opening


18


of the partition wall


3


. The flange-like end


16


is centered in the receptacle


17


and projects beyond the edge of the receptacle. In this way, the flange-like end


16


forms an axially pretensioned sealing means between the partition wall


3


and the end wall


12


of the carburetor


4


and this is so because of the elastic material of the connecting tube


8


. The sealing means can also be a paper or an elastomeric seal of which the elastomeric seal can be vulcanized to the end face


12


of the carburetor or to the partition wall


3


or the elastomeric seal can be configured as a loose O-ring. The end face


12


can also have a cylindrical or conical recess or rise which presses the sealing means with a radial and/or an axial component. Furthermore, a sealing action between the end face


12


of the carburetor


4


and the connecting tube


8


can be achieved with a contact surface, which is configured to be planar or conical, while omitting additional sealing means.




At the other end


19


of the carburetor


4


, an intake filter


70


is connected which includes an air filter housing


20


and a filter element


41


placed therein. The end face


21


of the carburetor


4


faces toward the intake filter


70


and lies on a corresponding wall


22


of the air filter housing


20


. Centering means are likewise arranged between the end face


21


of the carburetor


4


and the wall


22


of the air filter housing


20


in order to place the flow opening


23


in the correct position relative to the intake channel section


9


. The centering means engage in corresponding centering openings of the carburetor.




At least one cylinder stub


24


is provided on the wall


22


in the embodiment shown. Preferably, two cylinder stubs


24


are provided which lie diametrically to the longitudinal center axis


13


of the intake channel section


9


. The cylinder stubs


24


engage in corresponding centering openings


25


in lateral flanges


15


of the carburetor


4


on both sides of the intake channel section


9


. The centering means can be configured on one of the two end faces (


12


,


21


) of the carburetor


4


or on both end faces. The centering means on one of the two end faces (


12


,


21


) of the carburetor


4


or on both end faces thereof can also be so configured that guide bolts


10


or cylinder stubs


24


are provided on the carburetor


4


which engage in corresponding openings fixed on the housing. A centering is also possible via centering rings or housing-fixed ribs which surround the carburetor


4


around the periphery thereof. The centering rings lie inwardly or outwardly with respect to the carburetor


4


.




The air filter housing


20


is configured to be approximately L-shaped when view in section. The air filter housing


20


is provided with a pivot arm


27


in the region of a leg


26


and the free end


28


of the arm


27


is expanded spherical-like or roller-like. The free end


28


engages into the support opening


31


of a support location


29


. The support location


29


can be provided as a support element made of plastic or metal on the base


30


of the carburetor space


5


and is attached with threaded fasteners, welded or fixed with adhesive. The support opening


31


faces the partition wall


3


.




The free end


28


of the pivot arm


27


is seated in the support opening


31


or latched therein so that the air filter housing


30


can be pivoted about the pivot axis


32


in the direction toward the partition wall


3


or can be pivoted away from the partition wall as indicated by the double arrow


33


. The pivot axis


32


lies transversely to the longitudinal center axis


13


of the intake channel section


9


and is especially at right angles to this longitudinal center axis


13


.




To assemble the air filter housing


20


, the housing


20


is pivoted in the direction toward the partition wall


3


until the wall


22


of the air filter housing


20


comes in tight contact engagement against the end face


21


of the carburetor


4


. A sealing element is advantageously arranged between the end face


21


and the wall


22


in order to prevent the intake of unwanted air.




A latching arm


36


is mounted on the air filter housing


20


in the region of the other leg


35


. A latch hook


37


is provided at the free end of the latching arm


36


. The latch hook


37


together with a latch edge


34


of the partition wall


3


conjointly define a latching device


40


via which the air filter housing


20


is latched to the housing as shown in FIG.


3


. For this purpose, the air filter housing


20


is pivoted so far in the direction of partition wall


3


until the latch hook


37


engages behind the latch edge


34


of the partition wall


3


.




Advantageously, the latch hook


37


extends over a segment length of the latch edge


34


so that a reliable support of the built-up clamping forces is ensured over a wide latch segment.




In the embodiment of

FIG. 4

, the air filter housing


20


is latched alternatively via a tension spring


55


in the operating position. The tension spring


55


is hooked into respective bores (


56


,


57


) in the partition wall


3


and the latching arm


36


at its respective ends. A further latching possibility is presented in

FIG. 5

with a threaded-fastener connection


54


between the latching arm


36


and the partition wall


3


. In the embodiment shown here, a bent-over portion


58


is provided on the partition wall


3


having a thickening


59


for accommodating a sheet metal screw


60


. In lieu of the sheet metal screw


60


, a threaded fastener with a nut, a snap catch or the like can be provided.




The elastic deformations, which result when latching the air filter housing


20


, generate a clamping force. This clamping force holds the carburetor


4


clamped in the longitudinal direction of the intake channel section


9


reliably between the partition wall


3


and the wall


22


of the air filter housing


20


. Also, elastic spring elements can be additionally provided between the carburetor


4


and the partition walls


3


and


22


to increase the clamping force. The carburetor


4


is fixed tightly into the housing in its mounted position. The sealing forces are simultaneously built up by the clamping forces. On the end faces


12


and


21


of the carburetor


4


, these sealing forces ensure a tight contact engagement against the supporting surfaces of the partition walls


3


and


22


. Sealing means can be provided to increase the sealing action between the end face


21


and the partition wall


22


as described for the end face


12


.




Preferably, the air filter housing


20


, its pivot arm


27


, the latching arm


36


and, if required, the latch hook


37


are all made of plastic and are preferably made as one piece of plastic.




The housing-fixed latched air filter housing


20


is open on the side facing away from the base


30


and is provided with a peripheral edge


38


on which a seal frame


39


of an areal filter element


41


is placed. The filter element


41


is fixed in its position by a holder


42


configured to correspond to the frame


38


. The holder


42


is formed on an air filter cover


43


. The air filter cover


43


is part of a hood


44


closing the apparatus housing


1


. The hood


44


is held at its end


45


facing away from the carburetor space


5


by a pivot bolt


46


in housing-fixed bearings


47


. In

FIG. 2

, the hood or cover


44


is opened and closed in the direction of the double arrow


49


about the pin axis


48


. In its closed position as shown in

FIG. 3

, the cover


44


is fixed tightly to the housing at its other end


51


via a latch device


50


.




The latch device


50


comprises a latching member which is provided on the air filter housing


20


and is configured as a latch tongue


52


in the embodiment shown. The latch tongue


52


engages in a latch opening


53


(

FIG. 2

) of the air filter cover


43


. In the operating position shown, the seal frame


39


is held by the holder


42


tightly against the peripheral edge


38


of the air filter housing


20


. The latch device


50


can also be provided on the apparatus housing


1


and especially in the region of the partition wall


3


.





FIG. 6

shows another embodiment wherein the guide bolts


10


are mounted as shown in the embodiment of

FIG. 1

but configured longer than the length of the carburetor


4


measured in the direction of the longitudinal axis


13


(FIG.


1


). The carburetor


4


has two flanges


15


on respective sides and these flanges have bores


14


which permit the carburetor to be threaded onto the guide bolts


10


. The air filter housing


20


includes two bores


61


which likewise facilitate threading the air filter housing onto the guide bolts


10


.




A projection


62


is arranged on the base


30


as a support


47


for the air filter cover


43


and is preferably configured as one piece with the base


30


. The air filter cover


43


has a holding arm


63


on its end


45


facing toward the base


30


. The arm


63


has an edge


64


which engages behind the projection


62


and has a flange


65


at the opposite-lying end


51


for a threaded-fastener connection


66


. The partition wall


3


is bent over in the direction of the flange


65


and likewise includes a flange


67


having a threaded bore


68


. The threaded bore


68


can be provided by injection molding in the flange


65


or can be configured as a separate nut which is placed, riveted or attached with adhesive. In the latched state of the air filter cover


43


, the two flanges (


65


,


67


) lie flush against each other and are held by a knurled screw


69


. A latch connection or bayonet connection or the like can be provided in lieu of the knurled screw


69


.




The holder


42


of the air filter cover


43


lies on the edge


38


of the air filter housing


20


. The clamping forces are generated via the holder


42


and the air filter housing


20


by tightening the threaded-fastener connection


66


and the elastic deformations associated therewith. The clamping forces hold the carburetor


4


between the partition wall


3


and the wall


22


of the air filter housing


20


.




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.



Claims
  • 1. A carburetor arrangement in a work apparatus with an internal combustion engine having an inlet channel, the carburetor arrangement comprising:an apparatus housing defining a space for mounting said engine therein; a carburetor having an intake channel extending therethrough and said intake channel defining a longitudinal axis; a partition wall disposed between said engine and said carburetor and said carburetor being positioned on said partition wall; said intake channel having a first end facing toward said partition wall and a second end facing away from said partition wall; a connecting tube projecting through said partition wall to connect said inlet channel of said engine to said intake channel of said carburetor at said first end thereof; an intake air filter communicating with said second end of said carburetor for conducting combustion air thereto; an additional wall; and, means for clamping and holding said carburetor between said partition and additional walls in the direction of said longitudinal axis.
  • 2. The carburetor arrangement of claim 1, wherein said partition wall is part of said apparatus housing.
  • 3. The carburetor arrangement of claim 1, said carburetor being a membrane carburetor.
  • 4. A carburetor arrangement in a work apparatus with an internal combustion engine having an inlet channel, the carburetor arrangement comprising:an apparatus housing defining a space for mounting said engine therein; a carburetor having an intake channel extending therethrough and said intake channel defining a longitudinal axis; a partition wall disposed between said engine and said carburetor and said carburetor being positioned on said partition wall; said intake channel having a first end facing toward said partition wall and a second end facing away from said partition wall; a connecting tube projecting through said partition wall to connect said inlet channel of said engine to said intake channel of said carburetor at said first end thereof; an intake air filter communicating with said second end of said carburetor for conducting combustion air thereto; an additional wall; means for clamping and holding said carburetor between said partition and additional walls in the direction of said longitudinal axis; said intake air filter being an intake air filter assembly including an air filter housing including aid additional wall as a wall thereof; and, said carburetor arrangement further comprising a support on said housing; said air filter housing being mounted on said support; and, said means including one of the following for latching said air filter housing securely in said apparatus housing: a tension spring, a threaded fastener connection or a latch connection.
  • 5. The carburetor arrangement of claim 4, wherein said air filter housing is pivotally connected to said support; and, wherein said latch connection comprises: a latch edge formed on said partition wall; a latch arm provided on said air filter housing; and, said latch arm including a latch hook on the end of said latch arm for hooking behind said latch edge to securely hold said air filter housing so as to clamp and hold said carburetor between said partition wall and said additional wall.
  • 6. The carburetor arrangement of claim 5, said air filter housing having a pivot arm thereon for holding said air filter housing on said support.
  • 7. The carburetor arrangement of claim 6, wherein said air filter housing, said latch arm, said pivot arm and said latch hook are a single integral piece made of plastic.
  • 8. The carburetor arrangement of claim 4, further comprising an air filter cover for closing and opening said air filter housing; said air filter cover having an end; a pivot support fixedly mounted on said apparatus housing; and, said air filter cover being pivotally connected to said pivot support so as to permit said air filter cover to be pivotally movable for opening and closing said air filter housing.
  • 9. The carburetor arrangement of claim 8, said end of said air filter cover being a first end; and, said air filter cover having a second end; and, said carburetor arrangement further comprising: releasable fixing means for releasably fixing said air filter cover to said apparatus housing at said second end of said air filter cover.
  • 10. The carburetor arrangement of claim 9, said releasable fixing means including one of a threaded fastener connection or a latch device.
  • 11. The carburetor arrangement of claim 10, wherein said latch device includes a latch member provided on said air filter housing; and, a latch opening formed in said air filter cover for receiving said latch member in latching engagement when said air filter cover is closed.
  • 12. The carburetor arrangement of claim 11, said latch member being a latch tongue on said air filter housing.
  • 13. The carburetor arrangement of claim 8, said air filter assembly comprising an air filter and a hold-down element disposed on said air filter cover for holding said air filter in place when said air filter cover is closed.
  • 14. The carburetor arrangement of claim 13, wherein said air filter is a filter element having a sealing edge; and, said hold-down element being in contact engagement with said sealing edge when said air filter cover is closed.
  • 15. A carburetor arrangement in a work apparatus with an internal combustion engine having an inlet channel, the carburetor arrangement comprising:an apparatus housing defining a space for mounting said engine therein; a carburetor having an intake channel extending therethrough and said intake channel defining a longitudinal axis; a partition wall disposed between said engine and said carburetor and said carburetor being positioned on said partition wall; said intake channel having a first end facing toward said partition wall and a second end facing away from said partition wall; a connecting tube projecting through said partition wall to connect said inlet channel of said engine to said intake channel of said carburetor at said first end thereof; an intake air filter communicating with said second end of said carburetor for conducting combustion air thereto; an additional wall; means for clamping and holding said carburetor between said partition and additional walls in the direction of said longitudinal axis; centering means on at least one of said walls; and, said carburetor having centering openings formed thereon for receiving said centering means therein.
  • 16. The carburetor arrangement of claim 15, wherein said centering means includes guide bolts on said partition wall for engaging corresponding ones of said centering openings of said carburetor.
  • 17. The carburetor arrangement of claim 16, wherein said guide bolts and said partition wall are configured as an integral piece made of plastic.
  • 18. A carburetor arrangement in a work apparatus with an internal combustion engine having an inlet channel, the carburetor arrangement comprising:an apparatus housing defining a space for mounting said engine therein; a carburetor having an intake channel extending therethrough and said intake channel defining a longitudinal axis; a partition wall disposed between said engine and said carburetor and said carburetor being positioned on said partition wall; said intake channel having a first end facing toward said partition wall and a second end facing away from said partition wall; a connecting tube projecting through said partition wall to connect said inlet channel of said engine to said intake channel of said carburetor at said first end thereof; an intake air filter communicating with said second end of said carburetor for conducting combustion air thereto; an additional wall; means for clamping and holding said carburetor between said partition and additional walls in the direction of said longitudinal axis; a first seal disposed between said carburetor and said partition wall and a second seal disposed between said carburetor and said additional wall.
  • 19. The carburetor arrangement of claim 18, wherein said connecting tube is made of an elastic material and said connecting tube has a flanged end in contact engagement with said carburetor to define said first seal.
Priority Claims (1)
Number Date Country Kind
199 46 574 Sep 1999 DE
US Referenced Citations (5)
Number Name Date Kind
4787924 Nagashima et al. Nov 1988 A
4788951 Nagashima Dec 1988 A
5073307 Langer et al. Dec 1991 A
5522355 Uhl Jun 1996 A
5595153 Hoppner et al. Jan 1997 A
Foreign Referenced Citations (1)
Number Date Country
3741018 Jun 1988 DE