US2635862A

US2635862A - Carburetor

Info

Publication number: US2635862A
Application number: US186419A
Authority: US
Inventors: Stoltman Donald
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1950-09-23
Filing date: 1950-09-23
Publication date: 1953-04-21
Anticipated expiration: 1970-04-21

Description

April 21, 1953 D. STOLTMAN CARBURETOR Filed Sept. 23 1950 3 //v vs/vroe DONALD STOLTMAN HIS, 447' TUBA/5Y5 Patented Apr. 21,1953

UNITED STATES PATENT GFFICE poration of Delaware Application September 23, 1950, Serial No. 186,419

8 Claims.

. 1 This invention relates to carburetors for internal combustion engines, particularly for automotive use and is an improvement on the type of carburetor disclosed in the currently pending application Serial No. 109,347, filed August 9,

The principal object of the present invention is to provide a fuel passage for conveying fuel from the fuel chamber to the fuel inlet or inlets through which fuel is discharged into the mixture passage of the carburetor which is so constructed that there will be a substantially even flow of fuel through such passage under all operating conditions and temperatures and in which the formation of vapor bubbles large enough to materially obstruct the flow of fuel is prevented at any temperature at which the engine may operate.

The above object is attained according to the present invention by the provision of a fuel conduit comprising two parts, one of which is a substantially vertical passage formed in a member extending downwardly into the fuel in a constant level fuel chamber, which connects at its upper end with a substantially horizontal passage leading to the main and idling fuel inlets. At the point Where the vertical and horizontal passages join, there is formed a small chamber, the walls of which are flared outwardly along a horizontal axis through such chamber in the direction of fuel flow therethrough. The walls of this chamber are also flared outwardly in a downward direction and its top surface is not normal to the axis of the vertical fuel passage, but lies at an obtuse angle thereto with respect to the direction of fuel flow. The chamber thus formed is without any sharp corners and while the provision of this chamber does not prevent completely the formation of vapor bubbles, it substantially prevents the collection and building up therein of bubbles of sumcient size to materially interfere with the even flow of fuel. This function is of very considerable importance particularly during idling at relatively high temperatures. Any bubbles which are formed are of small size andpass on to the fuel inlets without causing appreciable irregularity of flow of the latter. A chamber suchas described is shown and claimed in the application of Olsen, 5. N. 132,821, filed December 14, 1949. Associated with the chamber in the device shown in such application is a substantially horizontal passage which leads from said chamber and through which fuel flows to the fuel inlets, said passage being divided into two parts by ahorizontal partition plate and inthe Olson device almost all of such vapor bubbles as are formed 2 pass through the upper part of the horizonta passage.

According to the present invention, instead of having a flat horizontal partition plate in the fuel delivery conduit which leads from the aforementioned chamber as in the Olson device, applicant has provided a partition in the fuel conduit which is twisted or spiral in form and is so arranged that at the inlet end of the fuel passage adjacent the chamber, the plate is horizontal, but at the opposite or discharge end of the passage the plate is vertical, so that the passage on each side of the partition plate, at the discharge end of such passage, is at the same level.

When a flat horizontal partition is used and the discharge from the two parts of the delivery passage is at different levels, under some conditions, for example, when the carburetor is tilted or at an angle, the flow through the upper part of I the delivery passage, above the partition plate, is

apparently retarded to some extent which reduces the effectiveness of the partition. When a spiral or twisted partition of the form shown herein is employed. this retarding effect on the flow on one side of the partition, under the circumstances remation of a homogeneous fuel mixture, particularly at relatively high velocities.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Fig. l is a vertical section through the carburotor and fuel supply passage.

Fig. 2 is a detail section showing the construction of the fuel conduit where the vertical and horizontal passages connect.

Fig. 3 is a horizontal section on the line 3-3 of Fig. 2.

Figs. 4, 5 and 6 are sections on the lines 4--4, ti -5 and Et respectively, of Fig. 3.

Referring to Fig. 1, the carburetor shown there in comprises three separate castings numbered I, 2 and 3, respectively. The casting l is the carburetor outlet which is adapted to be connected with the intake manifold in the usual manner, the casting 2 is positioned above the outlet casting l and has a constant level fuel chamber 2a formed therein, while the casting 3 forms a cover for the fuel chamber and also has the air intake 4 formed therein. These three castings are separated by gaskets to form tight joints and to limit the transfer of heat between the castings as much as possible by preventing any metallic contact of the castings with each other.

In the outlet casting l, a throttle shaft 5 is suitably journalled and secured to such shaft is the usual throttle valve 6 which is manually adjustable by means not shown to control the volume of combustible mixture which is supplied by the carburetor to the engine.

In the casting 3 a choke valve 7 is positioned and this valve is secured to a shaft 8 Which is suitably mounted in the casting 3 for rotation. The choke valve in the carburetor disclosed herein is manually operated and, when the engine is operating at normal temperature, is adapted to be positioned in wide open position so as not to restrict the quantity of air entering the carburetor, but is adapted to be closed, or partly closed, by the manual operating connections when the engine is started cold in order to facilitate starting, the position to which the choke valve is moved being dependent upon the temperature at the time of starting. The choke valve is adapted to be moved to different positions by means of the arm numbered 9 which is adapted to be operated by a connection leading to the dash which is not shown herein, but is a conventional con struction. The arm 9 operates the choke valve through mechanism which need not be described herein, but is fully shown and described in the copending application above referred to. It may be said, however, that the operation of the choke valve by the arm 9 is effected through a spring Ill which holds the choke valve yieldingly closed, so that when the engine starts to run under its own power, the increase in engine suction which then occurs can pull the valve open to some extent against the force of the spring 10, so as to prevent over-choking.

In the carburetor shown herein, the choke valve is also designed to operate the throttle so as to move the throttle slightly toward open position when the choke valve is moved to its fully closed position in order that the idling speed may be somewhat increased when the choke valve is closed. This is done for the purpose of providing a somewhat faster than normal idling when the choke valve is closed at low temperatures which is desirable to prevent stalling. The operating connections between the choke valve and the throttle valve for effecting this movement are indicated generally by the reference numeral ll. Since this mechanism has nothing to do with the invention in this application, it is not illustrated in detail and will not be described, but such mechanism is'fully shown and described in the aforesaid copending application.

As already indicated, air is admitted to the carburetor through the air inlet 4 and fuel is supplied to thecarburetor through a main fuel nozzle l2 which terminates at the throat of a small Venturi tube 13 which, itself, terminates at the throat of a large Venturi tube I l integral with the casting 2 and forming a part of the mixture passage which extends vertically through the carburetor. The purpose of these Venturi tubes is, of course, to increase the velocity of air flow past the end of the main fuel nozzle E2 to create a partial vacuum adjacent the nozzle outlet in the usual and well known manner. Fuel is also supplied to the intake passage by an idling fuel inlet which is not shown herein, but which termi= 4 nates in an orifice communicating with the intake passage at the point adjacent and slightly pos terior to the edge of the throttle valve 6 when the latter is in closed position.

Fuel is supplied to both of these fuel inlets from the fuel chamber 2a and fuel is supplied to the latter through a coupling i5 which is screwed into the casting 3 and to which a fuel supply pipe extending to the main fuel tank of the vehicle is adapted to be connected. Fuel which is supplied through the coupling l5 enters a passage l6 formed in the casting 3 and flows through a passage in a nipple ll, which is screwed in the wall of the casting 3, and communicates with the fuel bowl 2a when the parts are assembled as shown in Fig. l. The flow of fuel through the passage I! into the bowl is controlled by a valve I 8 which cooperates with the passage 17 and rests on one arm of a lever l9 which is pivoted on a pin 28 fixed in position in the wall of the fuel chamber 2a. The lever I9 is connected to the floatmechanismwhich is not shown, but which is received within'the chamber 2a and when the fuel'level in said chamber reaches a definite height, the float lifts the lever 59 so as to close the valve I8 and cut off the flow of fuel into the float chamber in the usual way. The float mechanism is of conventional construction and has nothing to do with the invention which is claimed in this application.

Before describing the fuel passage which conveys fuel from the float chamber 2a to the main and idling fuel inlets, the construction of which constitutes the subject matter to which the claims of this application are directed, attention is called to the fact that the carburetor is provided with an accelerator pump which is operated manually upon sudden opening movements of the throttle to provide a charge of fuel in addition to the fuel supplied by the ordinary fuel inlet, in order to enrich the mixture for acceleration in the usual way. The construction of this accelerator pump constitutes no part of the present invention, but the pump includes a cylinder 25 into which fuel flows from the float chamber 20:, through a passage, not shown, and slidable in the cylinder is a pump piston 26 which isoperated by a spring 21 that is compressed when the throttle is opened suddenly, by means of an arm 26a which is pulled downwardly when the throttle is opened. This compression of the springeffects a delayed downward movement of the piston 26 which takes place as the spring expands following its compression by the throttle, as the latter is opened and as the piston moves downwardly, in the manner de scribed, it forces fuel from the space below the piston into the mixture passage to supply the additional fuel above referred to for acceleration purposes. This pump mechanism is fully shown and described in the copending application above referred to and will not be further described herein, since its construction is entirely immaterial so far as the present invention is concerned. A tube 28 which connects the upper end of the cylinder 25 with the carburetor intake serves as a vent for escape of any fuel bubbles which may collect within the cylinder 25 and as a vent for the fuel chamber 2a. 7

The construction which has been generally described above is the same as that disclosed in application S. N. 109,347 and'the construction of the entire carburetor is the same as what is shown in such application except the fuel conduit which supplies fuel to the main and idle fuel inlets. In this application, as in the earlier application, such fuel conduit comprises three parts or passages which together make up a conduit shaped substantially like an inverted U, one part or passage being substantially vertical and extending downwardly into the float chamber and connecting at its upper end with a horizontal passage formed. in casting 3, which, in turn, connects at its other end with a substantially vertical. passage that extends downwardly to the idling fuel inlet, the main fuelinlet communicating with the horizontal portion of the passage substantially midway between its ends. As-shown in Fig.- 1, the fuel conduit includes a vertical pas sage formed in a member 3| which, at its upper end, is secured in any suitable way in a bore or chamber 3m formed in the casting 3. This member, at its lower end, has a calibrated plug 32 screwed into it which meters the fuel sup"- plied to passage 30. Communicating with the chamber 3la is a horizontal passage 33- which, at its left end, as shown in Fig. l, connects with a vertical passage 34- which extends downwardly in the wall of the casting 2 and communicates at its lower end with a passage 35 which leads to the idling fuel inlet, which is not shown herein but is of the same construction as shown in the earlier application. As shown, the chamber 31a is of larger diameter than either of the

passages

30 or 33, but does not have to be of the exact size shown. The horizontal portion 33 of thefuel conduit is of different diameters, that part of the passage lying between the chamber 3|a and the point of connection with the main nozzle being smaller than that part 35 of the passage 33 which lie to the left of the main nozzle in Fig. l. A plug 3! closes the left end of the passage and a tube 38 is fitted in that part of the fuel passage numbered 35. Such tube has a restricted opening 38a at its right end and terminates somewhat to the right of the vertical passage 34. A plurality of orifices 39 are provided immediately above the main nozzle l2 to admit air for purposes of effecting atomization of the fuel and a bushing 40 having a small orifice 4i therein is positioned within the main nozzle l2 to cause a flow therethrough at high velocity and to aid in the atomization of the fuel. This fuel passage as so far described, is of the same construction as that shown in the earlier application, except that the chamber am is not disclosed therein. In such application a passage such as 30 merely connects with another passage such as 33 of the same size as the passage 39, the axis of which is normal to the passage 38.

In the earlier application the passages corre-' sponding to 30 and 33 were simple cylindrical bores. and formed a sharp corner at the point where they connected. It was found that there was some tendency, particularly at high temperatures, for vapor bubbles to form and collect in this corner and for such vapor bubbles to gradually grow in size untila bubble of such large size was formed that the flow of fuel through the passage was partly or wholly restricted, particularly during idling. This bubble would increase in size until the passage was nearly blocked and would then break loose and pass through the passage 33 and finally out into the carburetor. This results in a somewhat intermittent and irregular iiow of fuel, causing some degree of irregularity of operation during idling. The device which constitutes the invention to which this application is directed is designed primarily to prevent any blocking of the fuel supply passage and any irregularity of engine operation: resulting therefrom at any operating. temperature. There fore, instead of having a simple fuel conduit such as shown in the earlier application and described above, according to the present invention, the chamber 31a is provided at the point of connection of the

passages

30 and 33. As already stated, the walls of this chamber are tapered or flared, so as to present no sharp corner in which vapor bubbles would tendto collect and build up as previously described, and while small bubbles are formed when operating at relatively high temperatures, these are not large enough to obstruct the flow and simply move along through the con-'- duit with the liquid fuel to the fuel inlets and into the mixture passage.

As illustrated, the chamber am has an upper surface 65 which is inclined upwardly in the direction of fuel. flow, asindicated in Figs. 1 and 3, and has

side walls

46 and 41 which are flared outwardly in a downward direction from the top surface 45 and terminate in the cylindrical opening 48 in which the upper end of the member 3| is received. The shape of the

surfaces

46, 41 and 48 will be readily understood from Figs. 2, 5 and 6. As best shown in Fig. 2, the

surfaces

46 and 41 are also flared outwardly in the direction of fuel flow along the axis of the horizontal passage 33.

Obviously, the top and sides of the chamber 31a merge into a single smooth surface free from any sharp corners and progressively enlarging in the direction of fuel flow.

The chamber 3la which has been previously described, has been found to greatly reduce the tendency for vapor bubbles to collect and build up to a size sufficient to materially interfere with the fuel flow because there are no sharp corners which might hold a bubble during the building up process; According to the present invention, however, means have been provided which will break up any bubbles which might be formed in such chamber into smaller size and will cause such small bubbles to flow through the passage leading from the chamber to the fuel inlets at high velocity so as to produce a substantially constant and regular flow of fuel during idling as well as when the main fuel inlet is functioning and the engine is operating under load.

This means comprises a partition plate 49 which is positioned in the horizontal passage 33 and divides this passage into two parts, 533 and 5t. This partition is twisted so as to give a whirl- I i ng motion to the fuel flowing through the passages as and El. As shown, the plate 59 is twisted through an angle of degrees, lying in a horizontal plane at its right end and in a vertical plane at the left end. However, the invention is not limited to a plate, such as 49, of any particular form and the twisting of the plate can be more or less as desired as long as the passage 33- at its intake end is divided horizontally and at its discharge end is divided vertically. It has also been found that the partition plate gives better results when it is somewhat shorter than the passage 33 and excellent results are obtained if its length is about four-fifths, or a little more than that of passage 33 from the end of passage 39 to the main fuel inlet.

The use of a flat partition plate 9, such as shown in application S. N. 132,821, has the effect of causing any small bubbles which may be formed in the chamber 31a. to flow primarily through the space 5!} above the partition and at considerably higher velocity than the substantially solid fuel column which flows through space 5 I. As already stated, under some operating conditions, particularly when the carburetor is tilted during idling at high temperatures, so that the discharge end of passage 33ris substantially lower than the intakeend of such passage,.the velocity of flow through the space v50 is materially reduced and this correspondingly reducesthe effectiveness of the partition plate and interferes with the supply of fuel for idling, tending to produce irregular operation of the engine at idling. By provision of the spiral partition plate, in accordance with the present invention, this reduction in flow velocity through the space 50 is largely avoided and smoother idling operation is secured. Also by causing the liquid fuel and fuel. vapor to move through spiral paths formed by passages Eiiand which discharge such fuel and vapor into the space to which air is introduced through orifices 35, the mixing action is aided particularly at relatively high flow velocities.

While the embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows: H

. l. A carburetor for an internal combustion engine having, in combination, a constant level fuel supply chamber, an intake passage provided with a throttle valve for controlling the-flow of combustible mixture therethrough, air and fuel inlets for admitting air and fuel to said mixture passage, a fuel conduit for conveyingfuel from the fuel chamber to themixture passage, said fuel conduit comprising a fuel passage communicating at one end with the fuel chamber and a second fuel passage communicating at one end with the discharge end of the first fuel passage and conveying fuel therefrom toward the mixture passage, the wall surface of said conduit at the point of connection of said first and second passages being formed in such a way that no sharp corners are presented by said wall surface whereby the formation and retention of vapor bubbles in said conduit at the point of connection of said passages is substantially prevented and a partition plate in said second fuel passage dividing said passage into two separate conduits through which the fuel flows, said plate being horizontal adjacent the inlet end of the passage so as to divide the passage into upper and lower conduits and vertical adjacent the discharge end of the passage so as to divide such passage into two conduits on the same horizontal plane.

2. A carburetor for an internal combustion engine having, in combination, a constant level fuel supply chamber, an intake passage provided with a throttle valve for controlling the flow of combustible mixture therethrough, air and fuel inlets for admitting air and fuel to said mixture passage, a fuel conduit for conveying fuel from the fuel chamber to the mixture passage, said fuel conduit comprising a fuel passage communicating at one end with the fuel chamber and a second fuel passage communicating at one end with the discharge end of the first fuel passage and conveying fuel therefrom toward the mixture passage, the wall surface of said conduit at the point of connection of said first and second passages being formed in such a way that no sharp corners are presented by said wall surface whereby the formation and retention of vapor bubbles in said conduit at the point of connection of said passages is substantially prevented and a partition plate in said second fuel passage dividing the passage into two separate fuel conduits through which fuel flows, said plate I the inlet end of said second'fuel passage and being twisted substantially ninety degrees so that it lies in a substantially vertical plane adjacent the outlet end of said second fuel passage.

3. A carburetor for an internal combustion engine having, in combination, a constant level fuel supply chamber, an intake passage provided with a throttle valve for controlling the flow of combustible mixture therethrough, air and fuel inlets for admitting air and fuel to said mixture passage, a fuel conduit for conveying fuel from the .fuel chamber to the mixture passage, said fuelconduit comprising a fuel passage communicating at one end with the fuel chamber and a second fuel passage communicating at one end with the discharge end of the first fuel passage and conveying fuel therefrom toward the mixture passage, the wall surface of said conduit at the point of connection of said first and second passages being formed in such a way that no sharp corners are presented by said wall surface whereby the formation and retention of vapor bubbles in said conduit at the point of connection of said passages is substantially prevented and a partition plate in said second fuel passage dividing the passage into two separate fuel conduits through which fuel flows and of a length slightly less than that of the second fuel passage, said plate lying in a substantially horizontal plane adjacent the inlet end of said second fuel passage and being twisted substantially ninety degrees so that it lies in a substantially vertical plane adjacentthe outlet end of said second fuel passage.

4. A carburetor for an internal combustion engine having, in combination, a constant level fuel supply chamber, an intake passage provided with a throttle valve for controlling the flow of combustible mixture therethrough, air and fuel inlets for admitting air and fuel to said mixture passage, a fuel conduit for conveying fuel from said constant level fuel chamber to the mixture passage, and comprising an upwardly extending passage which communicates at its lower end with the fuel chamber, a second passage extending substantially horizontally and forming a chamber at its point of connection with the upwardly extending passage having side walls which are flared outwardly in a downward direction and horizontally in the direction of flow of fuel therethrough, and a top surface tapered upwardly in the direction of flow of fuel therethrough, whereby the flow of fuel is facilitated and the retention of vapor bubbles therein of sufficient size to interfere with the fuel fiow is prevented, a partition plate in said second fuel passage, said plate lying in a substantially horizontal plane adjacent said chamber so as to divide the fuel passage into upper and lower conduits and in a substantially vertical plane adjacent the discharge end of the passage so as to form two separate fuel conduits at the same level.

5. A carburetor for an internal combustion engine having, in combination, a constant level fuel supply chamber, an intake passage provided with a throttlevalve for'controlling the flow of combustible mixture therethrough, air and fuel inlet's for admitting air and fuel to said mixture passage, a fuel conduit for conveying fuel from said constant level fuel chamber to the mixture passage'and comprising a generally vertical passage formed in a member extending downwardly into the'fuel in said fuel chamber and entirely surrounded by the fuel therein in order to prevent the heating of said member by conductivity and to reduce the formation of vapor bubbles in acease said passage, a substantially horizontal passage connecting with the vertical passage at its upper end and forming a chamber at its point of connection with the vertical passage having tapered side and top walls, whereby the retention in said chamber of any vapor bubbles that may be formed is prevented and the flow of fuel therethrough is facilitated, a partition plate in said second fuel passage of a length slightly less than the passage, said plate lying in a substantially horizontal plane adjacent said chamber so as to divide the fuel passage into upper and lower conduits and in a substantially vertical plane adjacent the discharge end of the passage so as to form two separate fuel conduits at the same level.

6. A carburetor for an internal combustion engine having, in combination, a constant level fuel supply chamber, an intake passage provided with a throttle valve for controlling the flow of combustible mixture therethrough, air and fuel ina lets for admitting air and fuel to said mixture passage, a fuel conduit for conveying fuel from said constant level fuel chamber to the mixture passage, and comprising an upwardly extending passage which communicates at its lower end with the fuel chamber to receive fuel therefrom, a second passage extending substantially horizontally and connecting at one end with the upwardly extending passage, a partition plate in said second fuel passage, said plate lying in a substantially horizontal plane adjacent the inlet end of the fuel passage so as to divide the passage into upper and lower conduits and in a substantially vertical plane adjacent the discharge end of the passage so as to form two fuel conduits at the same level.

7. A carburetor for an internal combustion engine having, in combination, a constant level fuel supply chamber, an intake passage provided with a throttle valve for controlling the now of combustible mixture therethrough, air anclfuel inlets for admitting air and fuel to said mixture passage, a fuel conduit for conveying fuel from said constant level fuel chamber to the mixture passage and comprising an upwardly extending passage which communicates at its lower end with the fuel chamber to receive fuel therefrom, a second passage extending substantially horizontally and connecting at one end with the upwardly extending passage, a partition plate in said second fuel passage of a length slightly less than the passage, said plate lying in a substantially horizontal plane adjacent the inlet end of the fuel passage so as to divide the passage into upper and lower conduits and in a substantially vertical plane adjacent the discharge end of the passage so as to form two fuel conduits at the same level.

8. A carburetor for an internal combustion engine having, in combination, a constant level fuel supply chamber, an intake passage provided with a throttle valve for controlling the flow of combustible mixture therethrough, air and fuel inlets for admitting air and fuel to said mixture passage, a fuel conduit for conveying fuel from the fuel chamber to the mixture passage, said fuel conduit comprising a fuel passage communicating at one end with the fuel chamber and a second fuel passage communicating at one end with the discharge end of the first fuel passage and conveying fuel therefrom toward the mixture passage, the wall surface of said conduit at the point of connection of said first and second passages being formed in such a way that no sharp corners are presented by said wall surface whereby the formation and retention of vapor bubbles in said conduit at the point of connection of said passages is substantially prevented and a spiral partition plate in said second fuel passage to cause the fuel flowing therethrough to move in a spiral path, the partition plate being so positioned in said fuel passage that its end adjacent the point of junction of the two fuel passages lies in a substantially horizontal plane when the carburetor is attached to the engine and the opposite end of said plate lies in a substantially vertical plane.

DONALD STOLTMAN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,777,141 Howden Sept. 30, 1930 1,893,920 Winfield Jan. 10, 1933 2,012,665 Gustafsson Aug. 27, 1935 2,126,132 Paasche Aug. 9, 1938