Aeration

BACKGROUND OF THE INVENTION

Heretofore, automatic choke mechanisms have employed either a diaphragm assembly or a pressure responsive piston in communication with a source of engine or intake manifold vacuum for moving the choke valve, against the resisting force of a thermostat tending to close _3gthe choke valve, to a partially open position, often referred to as the “qualifying position,” after a cold or relatively cold engine has been started. A stepped fast idle cam positioned by choke valve position then controlled idle throttle position. 40

It has also become accepted practice, in the prior art, to make such pressure responsive diaphragms or pistons of the “stopped” type; that is with either the “stopped” diaphragm or piston the initial qualifying position of the choke valve is determined by a positive mechanical stop 45 which precludes any further movement of such diaphragm or piston in the choke opening direction.

However, one disadvantage of the prior art arrangements, including the stopped type of diaphragm or piston employed by the prior art, is that there is no con- 50 trol or modulation of the choke position when the engine operating conditions are changed from cold fast idle to cold engine drive-away. Another disadvantage is that prior art choke systems result in a single fixed qualifying choke valve position for the higher air flow steps on the fast 55 idle cam.

That is, it is generally well known that a cold engine requires a combustible mixture which is of a richer fuelair ratio during cold idle engine operation in order to sustain engine operation and the initial choke opening is 60 selected in order to achieve such a richer mixture. However, upon undergoing cold drive-away conditions, at which higher engine speeds are also experienced, that initial opening of the choke valve usually results in an overly rich fuel-air ratio. This in turn results in the emission of unburned hydrocarbons, a reduction in overall fuel economy and often rough or sporadic engine operation.

The invention as herein disclosed and described is directly concerned with the solution of the above as well as other problems.

SUMMARY OF THE INVENTION

According to the invention, a carburetor for an internal combustion engine comprises a choke valve, a throttle valve, a source of vacuum, temperature responsive means influencing the position of the choke valve, and pressure responsive means communicating with the source of vacuum operatively connected to said choke valve, said pressure responsive means being effective to move said choke valve to a first partly open position when said engine starts and the throttle valve is in its cold or fast idle (closed) position, said pressure responsive means also being effective to move said choke valve to a variable second partly open position more nearly fully opened than said first partly open position when said throttle valve is moved from its above-defined idle or closed position toward a part-throttle position.

Accordingly, a general object of the invention is to provide in a carburetor having a choke valve, means for positioning the choke valve in a first partly opened position when the throttle valve is closed and for also positioning the choke valve in a variable second partly opened position more fully opened than said first partly opened position when the throttle valve is moved away from its said closed position to any higher air flow position.

Other more specific objects and advantages of the invention will become apparent when reference is made to the following detailed description and accompanying drawings.

DESCRIPTION OF THE DRAWINGS

In the drawings, wherein certain details may be omitted from one or more views for purposes of clarity:

FIG. 1 is a side elevational view of a carburetor, with portions thereof broken away and in cross-section, constructed in accordance with the teachings of the invention.

FIG. 2 is an enlarged fragmentary view of a portion of the carburetor of FIG. 1 sectioned axially through a cooperating pressure responsive choke actuating means constructed in accordance with the teachings of the invention;

FIG. 3 is a fragmentary cross-sectional view, similar to FIG. 2, but of a second embodiment of the invention; and

FIG. 4 is an enlarged fragmentary portion of FIG. 1 illustrating in greater detail certain of the elements shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now in greater detail to the drawings, FIG. 1 illustrates a carburetor 10, constructed in accordance with the invention, as comprising a carburetor body 12 formed to provide an induction passage 14 having the usual venturi restriction 16 and a throttle valve 18, within the induction passage downstream of the venturi 16, pivotally mounted on manually positionable throttle shaft 20. The entire carburetor assembly is suitably secured atop an engine intake manifold 22.

The throttle valve is opened, against the force of a spring 24 urging it closed, in the usual manner as by means of suitable linkage 26 connected between the throttle lever 28 and the operator’s foot pedal (not shown). As is customary, closure of the throttle 18 may be limited by an adjustable stop screw 30 adapted to be rotated with the throttle valve and engageable with one of a plurality of cam-like steps (not shown) formed on a fast idle cam (fragmentarily illustrated at 32) which is positioned generally by the choke mechanism 34 as through a lost motion linkage member 36.

W. S. ROBERTSON

AERATION

3,606,984

Sept 21, 1971

Filed May 9, 1968

Sheets-Sheet β

<img file="US3606984A_D0001.tif" />

FIG . 2

Sept. 21,.1971

W. S. ROBERTSON

AERATION

3,606,984

Filed May 9, 1968

Sheets-Sheet 3

<img file="US3606984A_D0002.tif" />

FIG . 3

United States Patent Office

3,606,984

Patented Sept. 21, 1971

3,606,984 AERATION William Swan Robertson, Manchester, England, assignor to Simon-Carves Limited, Cheadle Heath, Stockport, England

Filed May 9,1968, Ser. No. 727,802

Claims priority, application Great Britain, May 17, 1967, 22,936/67 Int. Cl. C02c 1/10

U.S. Cl. 261—91 11 Claims

ABSTRACT OF THE DISCLOSURE

Surface aeration apparatus for treating effluent liquid in which baffle plates are mounted below a rotatable surface aerator and are arranged to oppose any tendency for the effluent liquid to be rotated as a body with the aerator.

This invention is concerned with improvements in or relating to surface aeration.

In the surface aeration of, for example effluent liquids, e.g. industrial effluents and municipal sewage, using rotatable surface aerator members, at times when the liquid being aerated is shallow in depth, liquid tends to rotate as a body with the aerator member and this leads to inefficient aeration characteristics. This is a particular problem with large aeration lagoons where side walls of the lagoon are so far away from the aerator member as not substantially to affect the hydrodynamic conditions around the aerator member, and with circular aeration tanks.

It is an object of the invention to provide an improved surface aeration apparatus.

It is another object of the invention to provide an improved effluent liquid treatment plant comprising such an apparatus.

According to the present invention, there is provided a surface aeration apparatus comprising a rotatable surface aerator member and a plurality of radially disposed baffle plates provided around the axis of rotation of the aerator member and below the aerator member so as to control rotation of liquid being aerated as a body with the aerator member during operation of the apparatus, the distance between the inner end of each baffle plate and the axis of rotation of the aerator member is between 0.2 and 0.5 of the diameter of the aerator member.

The apparatus is particularly useful where the depth of the liquid being aerated is not more than 1.7 times the diameter of the aerator member, when the aerator member is circular in plan view.

According to another aspect of the present invention there is provided effluent liquid treatment plant including surface aeration apparatus as defined above.

The aerator member is used, for example, in a large aeration lagoon where side walls of the lagoon are so far away from the aerator member as not substantially to affect the hydrodynamic conditions around the aerator member, or in an aeration tank which is circular in plan view.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a sectional side view of surface aeration apparatus of an effluent liquid treatment plant;

FIG. 2 is a plan view of parts of the apparatus of FIG. 1, and

FIG. 3 is an overall plan view of the apparatus of FIG. 1.

Referring to the drawings, the plant includes surface aeration apparatus comprising a large aeration lagoon 12 with side Walls 13 provided in the ground and containing an effluent liquid which comprises, for example, an industrial effluent or municipal sewage. The lagoon 12 also contains activated sludge adapted to treat the liquid for disposal. A rotatable surface aerator member 18 is mounted in the lagoon 12 and is rotated in the operation of the apparatus to aerate the liquid. Due to the size of the lagoon 12 side walls 13 of the lagoon 12 are so far away from the aerator member 18 as not substantially to affect the hydrodynamic conditions around the aerator member 18. The lagoon 12 is provided with an inlet pipe 16 and an adjustable outlet weir 14 and, in the operation of the apparatus, liquid flows continuously through the lagoon 12 entering by the pipe 16 and leaving by the weir 14.

The apparatus also comprises baffle means mounted in the lagoon 12 below the aerator member 18 and arranged to oppose in the operation of the apparatus, any tendency of the liquid to be rotated as a body with the aerator member 18. The baffle means comprises four vertical substantially planar baffles 44 each of which extends upwardly for a short distance from the bottom of the lagoon 12. The baffles 44 are symmetrically disposed around the axis of rotation of the aerator member 18 radially to said axis, a central space 45 being left between the baffles 44 (see particularly FIG. 2).

The aerator member 18 corresponds generally in construction and arrangement with the aerator member described in our U.K. patent specification No. 919,467 to which reference may be made. The aerator member 18 is mounted for rotation on a vertical shaft 2Ό and comprises an inverted frusto-conical shell 32 which is symmetrical about the shaft 20, a circular cylindrical boss 31 of small diameter secured to, and extending downwardly from, the shell 32 coaxially therewith the shaft 20 being secured in the boss 31, and a plurality of arms 33 each of which lies in a vertical plane and is secured to the boss 31, extending tangentially to the boss 31 along the lower surface of the shell 32; each arm 33 has an end portion 35 extending outwardly from the outer periphery of the shell 32; each end portion 35 has a horizontal upper edge coplanar with the outer periphery of the shell 32, and has a horizontal plate 36 which extends circumferentially from the said edge on the side of the arm 33 remote from the boss 31, and outwardly from the outer periphery of the shell 32. In the operation of the apparatus the aerator member 18 is rotated in the sense in which the plates 36 extend circumferentially from the arms 33.

The aerator member 18 is supported for rotation by a structure 60 on which is supported a motor 62 and a gear-box 64 arranged to rotate the shaft 20; the structure 60 is itself supported on the bottom of the lagoon 12. The motor 62 and the gear-box 64 are mounted on a platform 63 which is secured to the structure 60 by jacking screws 65; the level of the aerator member 18 is adjustable by adjustment of the jacketing screws 65.

Each baffle 44 extends upwardly from a flat elongated member 70. Outer end portions of the members 70 are secured to the structure 60 and inner end portions thereof are secured to a horizontal plate 67 which is provided to prevent scouring of the bottom of the lagoon 12.

The baffles 44 are particularly useful when the depth D of the liquid is not more than 1.7 times the diameter d of the aerator member 18 measured across the shell 32. The distance between the inner end of each baffle 44 and the axis of rotation of the aerator member 18 is between 0.2(7 and 0.5rf, preferably about 0.25A Four baffles being used, the height h of each baffle 44 is not less than 0.25D and its length L not less than 0.75rf, the product Lh being not less than 0.25D; preferable bafflle dimensions are either L=d, fi=0.25D or alternatively L=0.15d, /)=0.40.

3,606,984