US2197476A - Carburetor - Google Patents

Description

P 16 W J. LICHTENSTEIN CARBURETOR Filed Feb. 5, 19:56

ATTORNEY.

INVENTOR N fc 7E l:TE/N.

Patented Apr. 16, 1940 UNITED STATES CARBUBETOR Johann Lichtenstein, Levallois-Perret, France, as-

signor to Societe Generale des, Carburateurs Zenith, Levallois-Perret, France,

of Switzerland a corporation Application February 5, 1936, Serial No. 62,499 In Belgium February 8, 1935 3 Claims.

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tially by a. movable control member which controls the pressure at which liquid fuel is supplied to the fuel nozzle, the position of said control member being a function of the absolute pressure obtaining in the mixing chamber of the carburetor posterioreto the throttle and preferably of the absolute pressure which obtains in said mixture passage in the vicinity of the fuel nozzle. This control-member will be referred to hereinafter as the "manometric control member to facilitate the description. In the preferred embodiment, a second regulating device influencing the discharge offuel delivered by the fuel nozzle is controlled by the throttle. The manometric control member is arranged in such manner as to provide automatic functioning of the carburetor; that is to say, in such manner that the carburetor will deliver to the motor a mixture of the correct composition under all conditions of operation, and, when applied to an aircraft carburetor, is furthermore arranged in such manner as to provide an altimetric correction, that is to say in such manner as to modify the discharge of fuel in the degree required by variations in altitude.

It is lrnownthat the composition of the comv bustible mixture supplied to an internal combustion engine need not be an absolutely xed one, but that this composition may on the contrary vary Within certain limits. As a general rule, if the richness of the mixture is increased, the motor is enabled to develop greater power, but the specic consumption is higher in such case. It is of advantage, chiefly in aviation carburetors, to provide means for modifying the richness of the mixture delivered, so as either to get maximum engine power or to diminish the specific consumption. In general, this modi' cation of the richness is made at the will of the pilot.

The present invention has for its object an arrangement permitting the richness ofthe combustible mixture to be varied in carburetors ofv the type described in said Belgian patent.

According to the present invention, the influence of the manometric control member on the gg discharge of fuel may be varied by a supplemental adjusting member. This adjusting member will generally be manually controlled, but it will obviously be possible to control it automatically the same as other organs of the carburetor.

The description which follows, taken in connection with the appended drawing, will give, by

vway of example, a ready understanding of several ways of realizing the invention.

Figures 1 to 3 represent schematically, in longitudinal section, several forms of the invention.

` The carburetor shown in Figure l comprises mixture passage I'having an air inlet 2 and a `mixture outlet 3 connected to the motor. The effective cross section of the mixture passage I is controlled by a throttle 4 actuated by meanslof lever 5 and rod 6.

A fuel pressure regulator designated as a whole by the numeral 44 includes a fuel chamber I0 supplied with fuel under pressure through the conduit II andthe oriiice I4. The fuel chamber I0 is closed by a ilexiblemembrane I2 connected to a movable valve member I3 controlling the inflow of fuel to the fuel chamber IIl through the oriiice It. the arrangement being such that any increase in pressure within the fuel chamber I0 or any decrease in pressure within the adjoining chamber $5 tends to move membrane I2 upward ly and close the valve I3, I4.

A calibrated orifice 43 is supplied with liquid fuel by the4 fuel chamber IIJ of the pressure regulator t4. The second chamber 45 separated from' the fuel chamber IIJ by membrane I2 communicates freely with the air inlet 2 of the carburetor 2 through passages 46 and 4'I in such manner that the upper surface of the membrane I2 is subjected to the air supply pressure of the carburetor. calibrated orifice 43 is controlled by a tapered needle 48 the shaft 49 of which passing through guide 21 is controlled by the throttle valve t through the intermediary of the arm 2B of lever 5, link wand lever' 30 turning about the axis 2i.

Calibrated orifice 43 opens into an intermediate chamber communicating with the venturi 8 through a calibrated passage formed by the annular space between the orifice 5I and shaft 49 of needle 48. The fuel outlet is formed by extremity 59 of calibrated orifice 5I. termediate chamber 50 is also connected to the mixture passage I through a bypass |54 controlled by valve I55. The valve |55 may be operated by means of a lever |56. The intermediate chamber 50 is'in addition connected by a calibrated orifice 52 through passages 53 and 41 with the air inlet of the carburetor.

An enclosed manometric capsule 55 has one end attached to a wall of chamber 55, which communicates with the venturi l through passage 5l The incontrols calibrated orifice 36.

opening into the venturi at a point 58 where the pressure is approximately the same as at the fuel nozzle 59. At its opposite end capsule 55 can'ies a cylindrical shaft 68 passing through guide 6| and having a. tapered portion 54 controlling the effective cross section of orifice 52.

'I'he fuel delivered through calibrated orifice 43, before reaching the fuel outlet 59, is emulsied with the air supplied from the air inlet 2 to the intermediate chamber 56 (depression chamber) through passages 41 and 53 and orice 52.

Under normal operating conditions the valve |55 is opened in such a manner that part of the emulsion is delivered to the mixing chamber 8 through bypass |54.

The depression which is transmitted to the intermediate chamber 50 through fuel outlet 59 and the bypass |54 is lowered by the air entering through orifice 52, and the depression transmitted to the intermediate chamber 50 depends on the effective cross section of orice 52 which is regulated by the tapered valve member 54. This cross section depends on the elongation of the capsule 55 and this elongation in turn depends on the absolute pressure existing in the mixing chamber 8 and in chamber 56. The profiles of member 54 and of needle 48 are designed to produce automatic functioning and altitudinal correction, so that, the carburetor will deliv'er a correct mixture under all working conditions and altitudes.

If valve |55 is closed by operating lever |56, the cross section available to the emulslfled fuel by intermediate chamber to the mixing chamber 8 becomes reduced and consequently the depression transmitted to the intermediate chamber 50 is weaker. Orifice 43, which supplies fuel to the intermediate chamber 58, is thereby subjected to a weaker depression. Its output diminishes and the mixture delivered by the carburetor becomes leaner.

The carburetor shown in Figure 2 di'ers from the carburetor shown in Figure 1 in that the bypass |54 is omitted. In addition the intermediate chamber 50 is connected to passage 41 leading to the carburetor air inlet 2 both through orifice 52, the section of which is regulated by tapered valve member 54, and through bypass |51 controlled by valve |58. Lever |59 permits the operation of valve |58. Under normal operating conditions valve |58 is closed, but if one opens the valve by means of lever |59 the intermediate chamber 50 receives additional emulslfying air through bypass |51 with the result that the depression transmitted to the intermediate chamber 50 is diminished and the nal mixture supplied by the mixture is leaner.

The carburetor shown in Figure 3, showing the application of the invention to the carburetor shown in Figure. 5 of the Belgian patent, diers from the carburetor shown in Figure 1 only in the arrangements which regulate the depression transmitted to the intermediate chamber 50. In the carburetor shown in Figure 3 the intermediate chamber 50 is connected by a restricted passage 62 with compartment 63. Compartment 63 connects in turn with the carburetor air inlet through calibrated orifice 64 and passages 53 and 41. Compartment .63 connects in addition with chamber 65 .through calibrated orifice 66. Chamber 65 communicates freely through passage |66 with venturi 8 at a point 61 where the pressure closely approximates that at the fuel outlet 59. In chamber 65 is located an enclosed manometric capsule 68 carrying a profiled needle 69 which The liquid fuel supplied by orice 43 is emulsiiied anterior to its outlet at 59 into the mixing chamber by air supplied to the intermediate chamber 56by orifice 62, chamber 63, orifice 64 and passages 53 and 41, which terminate in air inlet 2. Orifice 62 may have a relatively large section since its purpose is simply to create a slight difference in pressure between chamber 63 and chamber 56 in order that the fuel coming from chamber 50 can reach chamber 63, chamber 65 and venturi 8 after having passed through oriiice 66.

Instead of providing a bypass connecting intermediate chamber 50 to venturi 8, obviously a bypass connecting chambers 65 and 63 might be provided.

Bypass |54 could similarly be replaced by a bypassconnecting chamber 63 to passage 41 and controlled by a valve, this bypass being similar to bypass |51 shown in Figure 2.

I claim:

l. In a carburetor, an induction passage, a throttle controlling the same, a fuel conduit discharging into said induction passage posterior to the throttle, a fuel reservoir supplying liquid fuel to said fuel conduit, a throttle controlled variable restriction in the fuel conduit, and means for bleeding air into said fuel conduit comprising an air passage connecting the induction passage with the fuel conduit posterior to the Variable restriction, a manually operable valve in said air passage for varying the effective cross-section thereof, a second air passage connecting the induction passage with the fuel conduit posterior tothe variable restriction, a manometric capsule subjected to pressures inthe induction passage and yieldable in response to variations in said pressures, and a valve connected to said capsule to be operated thereby for varying the effective cross-section of said second air passage.

2. In a carburetor, an induction passage, a throttle controlling the same, a fuel conduit discharging into said induction passage in a region of depression created by the restricting effect of said throttle, a fuel reservoir supplying fuel to said conduit, a throttle controlled variable restriction in said conduit, and means for varying the suction in said fuel conduit comprising two air passages connecting said induction passage with the fuel conduit posterior to said variable restriction for bleeding air thereinto, and independently operable manual means and means including a manometric capsule yieldingly responsive to the pressures in the induction passage for varying the air bleeding effectiveness of said air passages.

3. In a charge forming device, an induction passage, a throttle controlling the same, a fuel conduit discharging into said induction passage posterior to the throttle, a throttle controlled variable restriction in said conduit, a variable pressure chamber in the fuel conduit posterior to said restriction, and means for varying the pressure in said variable pressure chamber com- 'prising two passages connecting the induction passage and the variable -pressure chamber, at least one of said passages bleeding air into said chamber, means including a manometric capsule yieldingly responsive to variations in the pressure in the induction passage for varying theA effectiveness of said air bleed passage, and manu- Vally operable means for varying the cross-sectional area of the other of said passages.

JOHANN LICHTENSTEIN.

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