Die Erfindung betrifft eine Verstellsicherung für eine Einstellschraube (10) an einem Vergaser (1) in einem handgeführten Arbeitsgerät wie einer Motorkettensäge oder dgl.. Die Verstellsicherung besteht aus einer auf dem Kopf (12) der Einstellschraube (10) drehfest gehaltenen Kappe (20), die mit geringem radialen Spiel von einer etwa koaxial liegenden, gehäusefesten Wandhülse (30) umgeben ist. Die Kappe (20) weist eine Begrenzung des Drehwinkels (S) in der Wandhülse (30) auf, wozu in Drehrichtung der Einstellschraube (10) ein gehäusefester Drehanschlag (33) vorgesehen ist. Um eine Zerstörung der Drehbegrenzung durch Einleiten zu großer Drehmomente in die Verstellsicherung zu vermeiden, ist vorgesehen, in der Kappe (20) eine Durchgriffsöffnung (40) auszubilden, über die ein Werkzeug in eine Eingriffsöffnung (14) im Kopf (12) der Einstellschraube (10) eingesetzt werden kann. Die Durchgriffsöffnung ist dabei durch die Verwendung eines metallischen Materials in ihrer Form und in ihrer Öffnungsweite (D) begrenzt, so dass ein größeres Werkzeug als das Einstellwerkzeug nicht durch die Durchgriffsöffnung in den Kopf der Einstellschraube eingeführt werden kann. Ferner ist zur Begrenzung eines maximal zulässigen Verstellmomentes die Eingriffsöffnung (14, 15) in ihrer Form und/oder Öffnungsweite nachgiebig ausgebildet.

A carburetor body including a cylindrical bore, a frusto-conical stepped shoulder portion, a valve chamber and an outlet passage which are coaxially provided and sequentially reduced in the inner diameter inwardly from an end wall face thereof. A plastic retainer and a metal collar are interference fitted into the cylindrical bore. The fuel regulating needle valve includes a screw shaft portion, an unthreaded stem portion and a valve tip which are sequentially reduced in the outer diameter from a head of the fuel regulating needle valve toward the valve tip. The threaded shaft portion is screwed into a threaded bore formed in the metal collar, and at the same time, screwed into an axial bore formed in the plastic retainer while cutting thread grooves. The unthreaded stem portion projects from a distal end cylindrical portion of the plastic retainer into the valve chamber, and the valve tip projects from the valve chamber into the outlet passage.

A fuel needle valve assembly of a carburetor has a retainer which yieldingly restrains the rotational fuel flow setting capability of the needle valve. The retainer engages a shank of the needle valve and a parallel shaft, both of which project from the carburetor body. The retainer exerts a force which laterally displaces the projecting shank with respect to the shaft. The retainer has sufficient strength to ensure the factory set rotational setting of the fuel needle valve does not alter when a limiter cap is press fitted to a distal head of the needle. Furthermore, wherein the shaft is also a shank of a second needle valve, the same retainer laterally displaces the projecting shanks of both needle valves.

A carburetor fuel mixture adjustment assembly has a threadable holder which suppresses rotation of a needle valve body disposed within an elongated receptacle defined within a carburetor body. The threadable holder is rigidly engaged within a threading chamber of the receptacle. During assembly, the needle valve body is extended through a bore of the holder as a threading portion of the valve body rotateable cuts an interior threading groove into the threadable holder. The threadable holder is held rigidly within the threading chamber by the carburetor body. A sealing holder is disposed within the receptacle axially inward of the threadable holder and is prevented from rotating within the receptacle by the threadable holder. A stem holder portion of the sealing holder assures a needle portion of the needle valve assembly remains concentrically disposed within an outlet orifice of a fuel chamber of the receptacle. A shank holder portion of the sealing holder engages radially between a shank chamber wall of the carburetor, which axially defines a shank chamber of the receptacle, and the shank portion of the needle valve body disposed concentrically to and axially inward of the threading portion. Engagement of the shank holder portion prevents air from entering through the receptacle and into the sub-atmospheric fuel chamber, thereby assuring stable fuel flow through a fuel passage intersected by the fuel chamber and stable engine operation.

A carburettor (2) and a fuel feeding system including an air suction passageway (4) through which air is fed, and a fuel feeding passageway (10) which is disposed so as to be intersected to the air suction passageway (4) and through which fuel is fed, the air suction passageway (4) and the fuel feeding passageway (10) being interconnected to each other. A roughened surface portion (40,42,44) is formed on a wall surface (18a) of at least one of the air suction passageway (4) and the fuel feeding passageway (10) to generate turbulence in fluid flow and promotion carburetion and atomisation of the air-fuel mixture due to turbulence. The tip portion (36) of a jet needle (18) serving as a part of the fuel feeding passageway (10) may be provided with a substantially flat surface portion (132) or a substantially conical surface portion (132b) having a vertical angle above 145 degrees.

To improve responsiveness of fuel supply control, a rotary carburetor 100 has a nozzle 8 including a fuel discharge port 8a and a needle 10 disposed coaxially with the nozzle 8 and disposed with a portion inserted into the nozzle 8. The needle 10 can be displaced relative to the nozzle 8 to change an effective area of the fuel discharge port 8a. The rotary carburetor 100 has an electric motor 14 for displacing the needle 10 along an axis, and a drive mechanism component 12 interposed between the electric motor 14 and the needle 10 and converting a rotational movement of the electric motor into a linear movement.

Die Erfindung betrifft eine Verstellsicherung für eine Einstellschraube (10) an einem Vergaser (1) in einem handgeführten Arbeitsgerät wie einer Motorkettensäge oder dgl.. Die Verstellsicherung besteht aus einer auf dem Kopf (12) der Einstellschraube (10) drehfest gehaltenen Kappe (20), die mit geringem radialen Spiel von einer etwa koaxial liegenden, gehäusefesten Wandhülse (30) umgeben ist. Die Kappe (20) weist eine Begrenzung des Drehwinkels (S) in der Wandhülse (30) auf, wozu in Drehrichtung der Einstellschraube (10) ein gehäusefester Drehanschlag (33) vorgesehen ist. Um eine Zerstörung der Drehbegrenzung durch Einleiten zu großer Drehmomente in die Verstellsicherung zu vermeiden, ist vorgesehen, in der Kappe (20) eine Durchgriffsöffnung (40) auszubilden, über die ein Werkzeug in eine Eingriffsöffnung (14) im Kopf (12) der Einstellschraube (10) eingesetzt werden kann. Die Durchgriffsöffnung ist dabei durch die Verwendung eines metallischen Materials in ihrer Form und in ihrer Öffnungsweite (D) begrenzt, so dass ein größeres Werkzeug als das Einstellwerkzeug nicht durch die Durchgriffsöffnung in den Kopf der Einstellschraube eingeführt werden kann. Ferner ist zur Begrenzung eines maximal zulässigen Verstellmomentes die Eingriffsöffnung (14, 15) in ihrer Form und/oder Öffnungsweite nachgiebig ausgebildet.

A carburetor fuel mixture adjustment assembly has a threadable holder which suppresses rotation of a needle valve body disposed within an elongated receptacle defined within a carburetor body. The threadable holder is rigidly engaged within a threading chamber of the receptacle. During assembly, the needle valve body is extended through a bore of the holder as a threading portion of the valve body rotateable cuts an interior threading groove into the threadable holder. The threadable holder is held rigidly within the threading chamber by the carburetor body. A sealing holder is disposed within the receptacle axially inward of the threadable holder and is prevented from rotating within the receptacle by the threadable holder. A stem holder portion of the sealing holder assures a needle portion of the needle valve assembly remains concentrically disposed within an outlet orifice of a fuel chamber of the receptacle. A shank holder portion of the sealing holder engages radially between a shank chamber wall of the carburetor, which axially defines a shank chamber of the receptacle, and the shank portion of the needle valve body disposed concentrically to and axially inward of the threading portion. Engagement of the shank holder portion prevents air from entering through the receptacle and into the sub-atmospheric fuel chamber, thereby assuring stable fuel flow through a fuel passage intersected by the fuel chamber and stable engine operation.