US2098479A - Automatic choking device - Google Patents

Description

Nov. 9, 1937. c D AMMQN 2,098,479

AUTOMATIC CHOKING DEVICE Filed April 22, 19:55

Fig. 2

grwc/wbo'v Charles D. Amman Summon;

- Patented Nov. 9, 1937 UNITED STATES PATENT OFFICE 1.00am au'ronumc cnoxmo' nnvrca Charles D. Amman, Lincoln, Nebr.

Application April 22, 1935, Serial No. 17,675

8 Claims. (Cl. 128-119) w invention relates to choking devices for internal combustion engines, an object of the invention being the provision of a device which permits the starting of the engine when cold and. when it requires some form of choking arrangement in order to enrich the mixture of gas so that it will readily explode, the device being so designed as to provide means whereby the richness of the'mixture is reduced to its normal strength when the engine becomes warmed up.

Another object of the invention is the provislon of an air restricting valve for the air intake to the carburetor, the valve being actuated by the suction stroke and in direct proportion to the speed of the suction stroke.

Another object of the invention is the provision of an air restricting valve for the intake to a carburetor, the valve being automatically actuated to an extent proportional to the velocity oi the inflowing air.

Another object of the invention is the provision of a valve mechanism for the air intake of a carburetor, the valve being actuated to move a greater distance to permit a more free flow of air and in proportion to the increasing speed of the engine as the engine warms up.

Still another object of the invention is the provision of a choke valve which remains in slightly restricted position and which is automatically actuated in proportion to the velocity of the air and in response to the movements of a thermostatic element which in turn is responsive to the heat of the engine.

Having in view these objects and others which will be pointed out in the following description,

I will now refer to the drawing,v in which Figure 1 is a view in side elevation of .the carburetor and of a fragment of the exhaust manifold with my device attached thereto.

Figure 2 is a view in vertical section of my device and of the exhaust manifold, the latter being shown in different angular relation to the carbureter.

The carburetor includes the usual air intake III, the fuel line H, the fuel valve l2 and a throttle valve I 3. My air intake is provided with a valve H having a valve stem l5 which is connected to the exhaust manifold l6 by means of a strip of thermal metal ll. The valve it includes a lower disk of leather or similar material backed by a metallic disk against the upper surface of the leather disk.

The valve ll is a weighted valve so that it 55 will remain seated when the engine is not in operation. The weight of the valve should be suilicient to hold it down on its seat but it may be weighted by attaching additional weights or by use of any of the well known equivalents such as a spring. on the other hand, the weight 5 should be light enough to permit the suction to open the valve during the operation of the engine.

The strip ll of thermal metal is passed through a channel through the exhaust mani- 10 fold, the channel being preferably separated from the gas passage. The strip I1 is secured to the ear I8 projecting from the exhaust manifold,

a bolt l9 passing through the strip l1 and through the car it to clamp the strip 11 firmly in place. This connection may be made regardless of the position of the exhaust manifold as indicated in Figures 1 and 2. In other words, the plane of movement of the strip Il may be at any desired angle with reference to the exhaust 20 manifold, depending on the direction of the manifold at this point. The connection may in fact be made in any suitably heated portion of the engine without departing from the spirit of my invention. 26

The strip I'I at its outer free end is shown as surrounding the valve stem l5 to which it is secured by means of a cotter pin 20 or other suitable means. The connection is made so that the valve 14 will be fully seated when the strip 30 i1 is in its inactive position.

When the engine is cold the valve I4 is fully seated. On starting the engine a suction is created which lifts the weighted valve sufllciently for the passage of some air. The restriction of 35 the flow of air movement results in a partial vacuum in the intake pipe on the suction stroke of the piston but this vacuum is immediately released upon completion of the suction stroke. This action causes the valve ll to assume alter- 40 nately an open and closed position, the movement being a fluttering one. As the engine and especially the exhaust manifold become heated the fluttering gradually decreases due to the positive action of the strip II. This strip being formed of two metals with different coeflicients of expansion, becomes distorted as its temperature rises so that it moves toward the dotted line position in Figure 2. In this position of the strip l1 the valve it will be in its full open position as shown in dotted lines so that the inflow of air in the direction of the arrows II and 22 into the air intake will remain unrestricted as long as the exhaust manifold remains heated. 56

' This enriches the explosive mixture permitting the engine to be started when cold or creating a rich enough mixture which will fire at low speeds. This restriction'is commonly obtained by some kind of hand-operated valve.

It is well known that there are other devices by which the action of this air-restricting valve is controlled thermostatically but in all prior cases the air-restricting valve remains closed until the thermostatic metal becomes heated. This causes the mixture to be uniformly rich regardless of engine speed while the engine is cold. This extra rich mixture covering the engine washes the lubricating oil oi! the cylinder wall and thus causes excessive wear. In my device the restriction of air is automatically controlled by the weighted valve and the thermostatic bar. When the engine is cranked slowly the suction on the air intake is light and the weighted valve is raised but very slightly. As the speed of the engine increases, the intake suction is correspondingly increased and the weighted valve is raised correspondingly higher, thus permitting a greater amount of air to flow through the carburetor and thereby automatically decreasing the richness of the fuel mixture. Furthermore, as the piece of thermostatic metal becomes gradually heated lifting the weighted valve from its seat, the weighted valve continues to be lifted by the intake suction, thus contributing to a. more rapid decrease in the richness of the fuel mixture than would be obtained by the piece of thermostatic metal operating alone. It is the structure on which this action of my choking device depends which is an improvement over all prior constructions. If, however, it is desired at any time to operate the device temporarily with the valve II in open position, the valve stem I! may be lifted manually without disturbing the thermostat.

Having thus described my invention in such full, clear, and exact terms that its construction and operation will be readily understood by others skilled in the art to which it pertains, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In an internal combustion engine, the combination of the air intake of the carburetor with an exhaust pipe, said air intake having a horizontal valve seat, a weighted valve normally seated on said valve seat, a valve stem projecting upwardly from said weighted valve, a bimetallic bar loosely secured to said valve stem, an abutment on said valve stem for limiting upward movement of said bimetallic bar relative to said valve stem, a heated channel positioned transversely through said exhaust pipe, said bimetallic bar passing through said heated channel, and a connection between said exhaust pipe and said bimetallic bar.

2. In combination with an internal combustion engine having an exhaust pipe and having a carbureter with an air intake and an intake poppet valve therefor biased to a closed position, a thermostatic elementmounted on the exhauitt pipe and having a one-way connection with said intake valve operable in the direction to unseat the valve, said thermostatic element adapted for operation when the pipe is heated to arrest the seating of the intake valve and prevent flooding of the carbureter and the supply of' a' too rich fuel mixture to the engine, and adapted when the exhaust pipe is relatively cold to permit free operation of the intake valve and obtain a rich starting fuel mixture.

3. In an internal combustion engine having a carbureter with an air intake and an exhaust manifold, an air restricting valve biased to close said air intake and adapted to be opened by the suction of inflowing air, a channel element carried by and traversing the duct of said exhaust manifold to be heated by the exhaust gases passing through the manifold, and a bimetallic thermostat secured at one portion to the manifold and extending through said channel element to be heated therein, said thermostat having a one way operating connection at another portion to said valve for maintaining the same from closing proportionately to the heating of the thermostat.

4. In combination with an internal combustion engine having an exhaust pipe and a carbureter with an air intake valve biased to a closed position and equipped with an outstanding stem for manually moving the valve into open position, a thermostatic element mounted in the exhaust pipe and slidably engaging the stem for free movement relative thereto in the direction of the closed position of the valve, and one-way connecting means between the thermostatic element and the valve stem operable upon the latter to unseat the valve when the thermostatic element is moved by heat influence in the exhaust pipe ima direction to unseat the air valve.

5. Means for maintaining open the usual suction opened air intake valve of an internal combustion engine carbureter when the engine is heated, comprising a thermostatic element adapted to be mounted in the exhaust pipe of the engine and operable by the heat of the exhaust gases from the engine, and a one-way opening connection between the thermostatic element and the air intake valve for holding the latter from seating when the thermostatic element is heated.

6. The combination of the air intake of a carbureter with a heated member of the engine, a poppet valve for closing and opening the air passage through said air intake, said valve normally urged to closing position but being free to pulsate in response to the variations in air pressure, and a connectionbetween the valve and said heated member which acts only in the direction for opening the valve when the member is heated and does not interfere with the closing of the valve when the member is cold.

CHARIES D. AMMON.

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