US3690304A

US3690304A - Carburetor construction to eliminate fuel accumulation at the reed valve

Info

Publication number: US3690304A
Application number: US3437A
Authority: US
Inventors: Kenneth C Schneider; Charles H Tuckey
Original assignee: Walbro Corp
Current assignee: Walbro Corp
Priority date: 1970-01-16
Filing date: 1970-01-16
Publication date: 1972-09-12
Anticipated expiration: 1989-09-12

Abstract

A uni-directional valve arrangement for two-cycle internal combustion engines which eliminates undesirable collection of pockets of fuel in the carburetor system and the resultant undesirable running characteristics, this being accomplished by venting from the mixing chamber of the carburetor system directly to the areas surrounding the unidirectional or ''''reed'''' valves so that an air fuel mixture moves through the restricted and dead pocket areas to keep them clean of fuel collections, thus preventing overrich comedown when a throttle is closed and preventing flooding under other running conditions.

Description

United States Patent Schneider et a1. 1 1 Sept. 12, 1972 [54] CARBURETOR CONSTRUCTION TO 1,600,007 9/1926 Mock ..261/D1G. 55 ELIMINATE FUEL ACCUMULATION 2,093,960 9/ 1937 Ericson ..261/D1G. 55 AT THE REED VALVE 3,353,525 11/1967 Nutten et a1. ..123/73 X [7 Inventors: Kenneth C. Schneider; Chimes H. 3,361,120 1/ 1968 Schneider ..123/73 Tuckey, both of Cass City, MlCh. Primary Examiner Mark M- Newman [73] Assignee: Walbro Corporation, Cass City, A i t E i -R B, Rmh

Mich. Attorney-Bames, Kisselle, Rajsch & Choate [22] Filed. Jan. 16, 1970 ABSTRACT [21] Appl' 3437 A uni-directional valve arrangement for two-cycle internal combustion engines which eliminates undesira- U-S. Cl. v, A ble collection of of fuel in the carburetor ..F02b y tem and the resultant undesirable running charac- [58] Field of Search ..123/73, 73 V, 73 A, 74; teristics this being accomplished by venting from the 261/DIG- 55; 137/513], 5133 mixing chamber of the carburetor system directly to the areas surrounding the unidirectional or reed References C'ted valves so that an air fuel mixture moves through the UNITED STATES PATENTS restricted and dead pocket areas to keep them clean of fuel collections, thus preventing overrich 1,788,358 1/1931 Goerg ..1.37/513.7 comedown when a throttle is closed and preventing ward 1 1 3.7 under other running conditions 1,092,279 4/1914 Martin et a1. ..261/DIG. 55 1,585,142 5/1926 Gillett ..261/DIG. 55 1 Claim, 1 Drawing figure CARBURETOR CONSTRUCTION TO ELIMINATE FUEL ACCUMULATION AT THE REED VALVE This invention relates to a Carburetor Construction to Eliminate Fuel Accumulation at the Reed Valve and is particularly directed to the use of a carburetor system with a two-cycle engine in which a unidirectional valve is provided at the entrance to the crankcase of an engine to receive a fuel and air mixture from the carburetor system of the engine.

In two-cycle engines, many efforts have been made to improve carburetion to prevent choking of the engine when the throttle is suddenly cut from full throttle to the idle range and also to prevent flooding when there is a sudden change from the idle range to half or full throttle. Many of the problems have resulted from what is called puddling which means a collection of liquid fuel in certain areas of the engine. A change of position or a change in the running condition may cause the collected fuel suddenly to enter the engine and cause flooding conditions.

The present invention has as its object the elimination of these undesirable conditions of puddling and the provision of an extremely simple revised structure which makes this possible. Many attempts have been made to solve this problem by complicated carburetion efforts and the present system eliminates all of these requirements by a simple change in the standard structures utilized in these engines.

Other objects and features of the invention will be apparent in the following description and claims wherein the principles of operation of the invention are set forth together with the best mode presently contemplated for embodiment of such principles.

A drawing accompanies the disclosure and the single view therein shows a cross-section of a carburetor engine combination illustrating the invention.

In the drawing, a carburetor structure is generally illustrated at having a mixing passage 12 with a throttle valve 14 and a choke valve 16. A diaphragm 18 controls a fuel inlet valve 20 of standard construction and fuel enters the mixing passage 12 through a main jet 22. The idle passages of the system include a passage 24 leading to a chamber 26 which has an idle port 28 at the throttle valve area of the mixing passage.

The carburetor is attached to a two-cycle engine crankcase 40 wherein a piston 42 operates in a cylinder 44 with the usual piston rod 46 and crankshaft 48. Interposed between the outlet end 50 of the mixing passage 12 and the inlet end 52 of the engine is a mounting flange 54 of a reed valve construction which is insulated from the metal housings by heat barriers 56 and 58. This is again standard construction. The reed valve has a tapered valve cage 60 with openings 62 which are closed by the flexible plates 64 commonly used in these reed valves. These plates are secured to the larger end of the tapered section by screws 66.

The invention lies in placing openings 70 in the flange 54 leading from the outlet of the mixing passage 12 to the pockets or corners 72 at the base of the reed valve in the entrance to the passage 74 and the inlet end 52. Thus, there is a venting of the so-called pockets or dead spaces surrounding the reed valve and this eliminates the so-called puddling of liquid fuel which can happen during the idling stage of the engine. Someal ih li 5 i ti e ltiltfifi rlfi illi wage? the globs of fuel will be carried into the engine and cause an overrich condition which may result in the engine stalling. Other times, during the open throttle condition, this puddling will occur and a quick shut down to idle may cause a choking of the engine with an overrich mixture.

Under other circumstances, during idle running conditions, the puddles will accumulate in these pockets and when the engine changes position, as in the case of chain saws, for example, which are shifted to many positions, the accumulated fuel will dump into the engine and kill it.

It has been found that the openings provided as indicated above will solve this problem. The size of the openings will be dependent on the size of the engine and can be readily calibrated by persons knowledgeable in the art for different size engines. For example, for an engine with a Bk-cubic inch capacity two-cycle, two holes having a dimension 0.052 inch were found to be suflicient. It is desirable that the holes be as small as possible to sweep the area clean since the larger the holes, the more possibility there is of a loss of power. Any reasonable sized hole will improve the conditions but a careful calibration will result in optimum operating efficiency. If a particular engine is intended to be used in a certain position, the holes can be introduced into the sides wherein there is most likelihood of the fuel accumulation.

Another advantage of the invention has been found in that an engine with the present invention incorporated therein can idle with a larger throttle opening so that tolerances between the throttle valve and the mixing passage can be reduced and thus the overall expense of manufacture is less. Thus, it can be said that the invention eliminates the idle puddling; it eliminates full throttle puddling; it provides a better comedown, that is, changing of speed from high open throttle to idle without the danger of flooding; it allows greater tolerances in the throttle valve fit.

What is claimed as new is as follows:

1. In an engine and carburetor combination wherein fuel and air mixture is introduced through a unidirectional valve, that improvement which comprises a unidirectional valve interposed between the mixing passage of the carburetor and the fuel passage of a crankcase housing of the engine, and means providing a plurality of fuel-air passages uncontrolled by said valve leading from the mixing passage of the carburetor to space in said fuel passage of the crankcase housing surrounding and outside said valve to sweep any accumulated liquid fuel into the crankcase housing.