US2457085A - Carburetor ice responsive device - Google Patents

Description

Dec. 21, 1948. w. H. KLIEVER CARBURETOR ICE RESPONSIVE DEVICE Filed Aug. 23, 1943 I IN V EN TOR.

' to the degree of formation.

Patented Dec. 21, 1948 UNITED STATES PATENT OFFICE CARBUBETOR ICE RESPONSIVE DEVICE Waldo H. Kliever, Minneapolis, Minn., asslgnor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minra, a corporation of Delaware Application August 23, 1943, Serial No. 499,653

4 Claims. (Cl. 177-311) My present invention relates to a device which responds to ice formation within a carburetor,

the formation of, or melt the ice, upon an icing condition occurring.

One object of the invention is to provide an electronically operated mechanism responsive to ice formation in a carburetor, by effecting variation in the capacity of a condenser in proportion Another object is to provide said condenser in the'for'm of elements already constituting a part of the carburetor so that additional elements need not be mounted in the air stream of the carburetor, thereby restricting the flow thereof. Also the weight of such additional parts is thus eliminated.

More specifically, it-is, my object to utilize the element of the carburetor in the air stream thereof, such as the air screen, a venturi, a

throttle, or a turbulence bar; such element being insulated relative to the carburetor wall, thereby forming the opposite plate of a condenser with respect to such wall.

Still a further object is to provide several of the elements in the air stream of the carburetor as one plate of the condenser, by connecting them in parallel so that an ice indicator is operated or a control function performed upon the occurrence of ice on any one of such carburetor elements.

An additional object is to coat each of the elements in the carburetor forming the condenser plate opposed to the carburetor wall, with lnsulating material, thus preventing the possibility of short circuiting the condenser by foreign objects entering the carburetor and bridging the venturi, throttle or turbulence bar. and the carburetor wall.

A further object is to provide an ice indicating and/or control arrangement located at the first point oi impact of the air with the carburetor or associated mechanism.

With these and other objects in view, my invention consists in the construction, arrangement ard type of aircraft carburetor showing my invention applied thereto, and diagrammatically an electronic circuit connected therewith for indi- 2 cating an icing condition and/or performing a control function.

Figure 2 is a bottom plan view of the lower, end of the carburetor showing particularly the turbulence bar thereof arranged to form one plate of a condenser; and

Figure 3 is a sectional view on the line 3-3 of Figure 2 to show how the turbulence bar may be insulated with respect to the carburetor wall.

On the accompanying drawing, I have used the reference character C to indicate, in general, an aircraft carburetor, although, of course, my invention may be applied to other devices. The carburetor shownis of a standard down-draft type. having a scoop 9 which connects to the throat l0 through which the air flows after flowing around and through a venturi V. The air then flows over the throttle T which is shown conventionally as the usual butterfly valve, and

finally over a turbulence bar B. The venturi V is ordinarily formed of metal such asaIuminum or brass, and is connected with the carburetor body by a flange and screw connection (not shown).

Ice is formed in carburetors or the appurtenances thereto in at least three different manners. So-called impact ice is formed where the air first enters the carburetor or attachments. This impact ice may form in the bend (not shown) of the scoop 9 or, if a screen is used in the scoop such as the screen S, the impact ice may be formed on such screen. Where a supercharger and intercooler are utilized ahead of the scoop and screen, it may be desirable to provide means to detect the presence of ice at whatever point the air originally enters the apparatus. Ice is also formed as a result of expansion of the air. This may occur, for example, when the air passes through the throttle of the carburetor. Again, ice is formed by reason of the evaporation of gasoline in the carburetor and the consequent cooling action brought about by such evaporation. Such ice can form when the temperature of the entering air is well above freezing and may form, for

example, on the turbulence bar (if used) or on the denser as it is only necessary, in order to have a condenser, that two conducting elements, whether plates or some other shape, be spaced with air or other dielectric between them. In this manner, a pickup is provided at the first point of impact of the air.

In the Joint between the venturi and the carburetor body, I place a gasket I2 of insulating material, and, of course, the screws that hold the venturi in place are suitably insulated in the manner hereinafter described for the screws I4 in Figure 3 that hold the turbulence bar B in position. Thus the venturi V may form one plate element of a condenser while the carburetor wall W forms the other plate element thereof. In some ar rangements, the venturi V may represent the first point of impact of the air The throttle T may also be insulated as with insulating strips I in the slot of the throttle stem I8. Thus, a pick-up is provided to detect ice formed as a result of expansion of the air passing through the throttle.

With respect to the turbulence bar B, some carburetors are provided with such bars and some are not. In some types of carburetors. these bars are termed X bars, and are for the purpose of forming a shield for the atomized fuel issuing from the nozzle openings 20 of the nozzle 22. The fuel is sprayed in a direction substantially parallel to the downstream side of the turbulence bar, and the bar effects a turbulence that more effectively and efficiently atomizes the fuel, and distributes it throughout the air stream flowing through the carburetor.

In order to insulate the turbulence bar B from the carburetor body, an insulating'sleeve 24 (see Figure 3) may be provided around the base of the nozzle 22 and an insulating gasket 20 may be interposed between the turbulence bar and the center boss 28 of the carburetor.

Under the heads of the screws I4 I also provide insulating washers 30, and the openings 32 for the screws where they pass through the central part of the turbulence bar B are enlarged to eliminate electrical contact between the bar and screws. Thus, the wall W of the carburetor, or in fact the entire carburetor body, including the boss 20 of the nozzle 22 may constitute one plate element of a, condenser, whereas the bar B constitutes another plate thereof. In addition, the nozzle 22 itself may be insulated from the remainder of the carburetor.

Any one of the elements S, V, T or B, or all of them if desired, as well as an insulated nozzle may be utilized as one plate of the condenser. For this purpose they are connected in parallel by means of a wire 34 shown diagrammatically in Figure 1, and a wire 08 is connected with the carburetor. or grounded thereto whereby the carburetor body forms the second plate of the condenser. The wires 34 and 38 thereby provide a pick-up circuit which may be utilized with any type of indicating and/or controlling apparatus, such for example as disclosed in my copending application Serial No. 463,259, filed October 24, 1942, now Patent No. 2,432,669, dated December 65 16, 1947. Such apparatus is generally indicate at 31. The wire I02 thereof is connected to wire 3| and wire IOI is connected to wire 08. A condenser 38 is connected between wires IOI and I03 and its capacity should equal that of the pickup 70 unit when there is no ice on any of the parts thereof. The indicator I30 having needle I" will then indicate the degree of icing of the parts.

It is connected to the apparatus 31 by wires I20 and III. Also, a control device I01, for instance, 7

a heating means for the carburetor may be utilized so as to melt any ice that forms thereon. The heating means may comprise for instance a heating element I00 for the carburetor wall supplied with current from a source of supply such as a battery I40 and may obviously be of a variable type to furnish a greater degree of heat when icing is more serious, as evidenced by greater increase in the capacity of the condenser connected with the wires 04 and III. The control device I" has one side connected to the apparatus 31 by wire I" while the other side thereof is grounded.

In operation, the capacity of the pick-up condenser increases with the formation of ice and further increases as the thickness of the ice increases. Ice does not need to form directly on the element used as a detector. Ice affects the condenser capacity as long as it forms at any point where there is some electrostatic field intensity as that surrounding any of the elements 8. V, T or B. Ice having a higher dielectric strength than air, icing causes the capacity of the condenser to increase and thereby varies the input circuit to the apparatus 31.

For a full description of the complete circuit used in connection with the pick-up condenser of the kind herein disclosed, reference should be had to my previously mentioned copending application, Serial No. 463,259, filed October 24, 1942. In said application a full description of the electronic circuit and its operation are disclosed.

Each of the condenser elements 8, V, T and B (as well as nozzle 22 if used as part of the pickup) is preferably coated with insulatin material such as a phenolic coating. This is indicated at 40 on each of the elements V, T and B,'and shown by stippling where the parts show in elevation. No

attempt has been made to show the coating in cross-section. The purpose of the insulating coating 40 is to prevent a possible short circuit of the condenser through a foreign object drawn into the carburetor and bridging across from the venturi, the throttle or the turbulence bar to the wall of the carburetor with resultant sparking. Also such a short circuit could occur across the turbulence bar and the nozzle 22. By providing 7 the insulation coating 40, the possibility of short circuiting the indicator I30 or the control means C out of proper operation is obviated.

In selecting an eiement of the carburetor to be used as one plate of the condenser when the wall of the carburetor is used as the other one, I have selected elements which are preferably in, or at least have a portion thereof in, the center of the air stream. Ice formation occurs here first because the velocity is greater and there is no heat from the engine by conduction or radiation to keep the temperature up as there would be if an element adjacent the wall of the carburetor were provided.- The variation in capacity of the condenser arrangement occasioned by formation or presence of ice, may readily be used to operate an'indioator such as at I30, or perform any control function desired in response to ice formation in the carburetor. The venturi, the throttle and the turbulence bar are each very well adapted for this purpose and may be used either separately or in any combination with each other as desired.

Furthermore. by using elements already in the carburetor no additional weight is added-an important consideration in aircraft, and no additional parts are inserted in the carburetor to project into the air stream and thereby obstruct airflow.

Some-changes may be made in the construction and arrangement of the parts of my device without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope without sacrificing any of the advantages thereoi.

I claim as my invention:

1. In a device of the class described, in combination, a'carburetor having a metallic wall and a metallic venturi subject to the formation of ice, dielectric means spacing said venturi and said wall to comprise an electrical condenser whose capacitance is varied by the presence and thickness of said ice, and means for making electrical connection to said condenser.

2. In a device of the class described, in combination, a carburetor having a metallic wall, venturi, and throttle, said venturi and said throttle being subject to the formation of ice, dielectric means spacing said venturi andsaid throttle from said wall to comprise electrical condensers whose several capacitances are varied by the presence and thickness of ice in their respective fields, and means for making electrical connection with said condensers in parallel.

3. In a device of the class described, in com- 30 bination: a carburetor having a metallic wall,

venturi, throttle, and turbulence bar, said venturi, throttle, and turbulence bar being subject to the formation of ice; dielectric means spacing said venturi, said throttle, and said turbulence bar from said wall to comprise electrical condensers whose several capacitances are varied by the presence and thickness or ice in their respective fields; and means for making electrical connection with said condensers in parallel.

4. A device of the class described comprising, in combination: a carburetor having a metallic wall and a plurality of electrically conductive members, including a venturi, a throttle, a turbulence bar, and a screen, cooperating to supply a combustible mixture 01 air and a fluid fuel, said wall and said members being subject to the formation of ice; means insulating said members from said wall to comprise therewith a condenser whose capacitance is varied by the presence and thickness of said ice; and means for making electrical connection to said condenser.

WALDO H. KLIEVER.

REFERENCES CITED The following references are of record in the

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