US3161787A - Automatic devices for controlling the starting means in internal combustion engine carburetors - Google Patents

Description

3,161,787 STARTING MEANS INE CARBURETORS 1962 1964 w VAN SAAN AUTOMATIC DEVICES FOR CONTROLLING THE IN INTERNAL COMBUSTION ENG Filed April 6,

lllllv lNvEA/TOR B7 8 t Mal ATTORNEYS United States Patent AUTOMATIC DEVICES FOR CONTROLLING THE STARTING MEANS IN INTERNAL COMBUSTION ENGINE CARBURETORS Willy van Saan, Neuss (Rhine), Germany, asslgnor to Socit Industrielle de Brevets et dEtudes (S.I.B.E.), Neuilly-sur-Seine, Seine, France, a society of France Filed Apr. 6, 1962, Ser. No. 185,749 Claims priority, application France, June 26, 1961, 866,108 1 Claim. (Cl. 310-4) As is well known an internal combustion engine carburetor comprises means for permitting cold engine operation, i.e. starting and running during the warm-up period. Said means, which are intended to increase the flow rate and the richness of the fuel and air mixture fed to the engine either act to close a choke valve or make use of a fuel and air mixture source different from that serving to supply mixture to be used for normal running of the engine. Said means will be hereinafter called starting means.

The present invention relates to automatic devices for controlling such starting means. Said automatic devices consist essentially of a heat response element, in the form of a bimetallic strip, subjected to the effect of the temperature of an electric resistor wire housed in the same casing as said element and fed with electric current when the engine is being started. The construction of said automatic devices is rather difiicult for the following reasons:

If the support of the resistor wire is made of a plastic material, such for instance as that designated by the trademark Bakelite, the electrical connecting members to which the ends of the wire are fixed can easily be secured to the support since this plastic material is an electrical insulator, but this material is not capable of correctly withstanding temperatures above 250 C. It is therefore necessary to position the resistor wire at a distance from the support, while fixing it to the connecting members. Precautions must even be taken to ensure a thermal isolation between the wire and the support to prevent the transmission of heat from one to the other through said electrical connecting members. If, on the other hand, the support is made of a metallic material, electric insulating means must be provided for the passage of the electrical connecting members through the support. In both cases the resistor wire can be supported only through its ends, ie in overhanging fashion. The vibrations of the engine give the resistor wire a pendular movement which tends to deteriorate it, the more so as this wire is often heated to red hot temperature, which reduces its mechanical properties. Furthermore, in view of this pendular movement, it is necessary to mount the wire at a relatively great distance both from the support on which the electrical connecting members are fixed and from the bimetallic strip, so as to avoid short circuits.

In these circumstances, such automatic control devices do not work well because the heat source consisting of the wire is at too great a distance fromthe bimetallic strip.

The object of the present invention is to obviate these drawbacks.

For this purpose, according to the present invention, the conductor wire, fixed to a cover plate of ceramic material which closes the casing in which the bimetallic strip is housed, is mounted bare in a groove formed in the inner wall of said cover plate and is held in said groove by a flange, preferably discontinuous, formed by the material of said cover plate along said groove, the bimetallic spring being located close to said inner wall of the cover plate, the coil formed by the resistor wire being preferably bent into a circle coaxial with the bimetallic spring.

A preferred embodiment of this invention will be hereinafter described with reference to the appended drawings given merely by Way of example and in which:

FIG. 1 is a diagrammatic elevational view of a downdraft carburetor with a device for controlling the starting means thereof, said device being shown in vertical section;

FIG. 2 is a detailed view corresponding to a section through the line II-II of FIG. 1.

The carburetor shown by the drawing comprises a body 1, provided with a vertical induction pipe 2 through which the air and fuel mixture flows in the direction of the arrow in FIG. 1, the flow rate of this mixture being adjusted by means of a throttle valve 3. Fuel is fed from a constant level chamber 4 and air flows in through the main air intake 5.

The starting means to permit starting and warm-up of the engine may be of any suitable construction and said means may be brought into or out of action by rotation of a spindle 6, journalled in a casing 7, fixed to the carburetor body 1.

The device for controlling said starting means comprises a lever 8 fixed on spindle 6 and the angular position of which is determined by its cooperation with the free end 9 of a bimetallic strip 10 which is spiral wound about a fixed pin 11 in line with spindle 8, and to which the inner end of said strip 10 is fixed, for instance by insertion in a slot 12 formed in spindle 6.

Pin 11 is carried by a support or cover 13, which forms the closing wall of easing 7. An electric resistor 14, mounted inside casing 7 is fed with electric current when the internal combustion engine is being started, the current being transmitted through connecting terminals 15.

It is known that, when the engine is stopped and cold, no current is fed to wire 14 and bimetallic strip 10 is itself cold occupying a position where spindle 6, which it controls, has the starting means ready for action. When the engine is started in these conditions, wire 14 begins to be fed with current and heats bimetallic strip 10 which is deformed and causes spindle 6 to rotate in the direction which causes the starting means to be gradually brought out of action.

Now, according to this invention, cover 13 is made of an insulating ceramic material capable of withstanding without danger temperatures as high as 800-900" C., i.e. higher than the maximum temperature to which wire 14 may be brought.

The cover 13 is provided with a housing capable of holding wire 14 in position and connecting terminals 15 extends through said cover 13.

The ceramic material may advantageously consist of steatite, steatite ware or any analogous product such as commonly used as insulating material in spark plugs.

With such a material it is possible to manufacture cover 13 by molding, terminals 15 and possibly pin 11 being secured in position during this operation.

As shown by FIG. 2, wire 14 is in the form of a coil bent into a nearly complete circle. In this case the housing formed in cover 13 consists of a groove 16 limited inwardly by projections 17. Thus whatever be the vibrations it undergoes, resistor wire 14 is fixed in position in groove 16 by said projection 17. Such an arrangement permits of placing wire 14 very close to thebimetallic strip, so that the heating of this strip is obtained with the maximum efiiciency. The wire cannot move in its casing under the effect of engine vibrations and its life is therefore increased.

Of course, the embodiment above described with reference to the drawings is given merely by way of example and has no limitative character.

What I claim is:

In an internal combustion engine carburetor, a heat re- 3 sponsive control device which comprises, in combination, a cylindrical casing comprising a cover made of a ceramic material capable of withstanding without damage temperatures as high as 800 C., the inner wall of said cover being provided with a groove extending along a substantially circular line, coaxial with said casing, the outer circular Wall of said groove being of substantially cylindrical shape, a heating resistor coil housed in said groove, two electric terminal members carried by said cover and connected to the ends of said resistor coil respectively, a bimetallic strip mounted in said casing in close proximity to said cover, said strip being spiral wound about the axis of said casing, the outer end of said strip being at a distance from said axis substantially equal to the radius of said groove, the opening of said groove being located oppositev said spiral wound bimetallic strip and extending toward the axis of said casing to a greater distance than said resistor coil, whereby the heat from said resistor coil is transmitted to most of said bimetallic strip, projections carried by the edge of said recess circular periphery for keeping said resistor coil in said groove, means for holding in fixed position the inner end of said bimetallic strip, and means operatively connected with the outer end of said bimetallic strip for transmitting the displacements of said last mentioned end.

References Cited by the Examiner UNITED STATES PATENTS 1,138,733 5/15 Copeman 219-37 1,612,174 12/26 Boller 338-311 X 2,180,779 11/39 Stribeck 174-138 2,245,672 6/41 Hunt 261-39 X 2,263,027 11/41 Beard 261-39 X 2,494,447 1/50 Mosthaf 219-37 2,942,596 6/60 Carlson 26139 X FOREIGN PATENTS 409,927 5/34 Great Britain. 937,037 3/48 France.

GEORGE D. MITCHELL, Primary Examiner.

HERBERT L. MARTIN, HARRY B. THORNTON,

Examiners.

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