US3829069A

US3829069A - Air valve carburetor with engine starting fuel enrichment means

Info

Publication number: US3829069A
Application number: US00259419A
Authority: US
Inventors: V Hailstone; R Harper; W Oliver
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1971-06-10
Filing date: 1972-06-05
Publication date: 1974-08-13
Anticipated expiration: 1991-08-13
Also published as: GB1355249A

Abstract

An air valve carburetor has an engine starting fuel supply line with an outlet downstream of the throttle valve and an inlet controlled by a spring opened valve that is closed by engine running level vacuum, a second valve in the supply line between the first valve and the outlet being connected to the throttle valve so that opening the throttle valve a predetermined amount moves the second valve to close the fuel supply line irrespective of a low vacuum level at this time being insufficient to maintain the inlet control valve closed.

Description

United States Patent 91 Hailstone et al.

[ AIR VALVE CARBURETOR WITH ENGINE STARTING FUEL ENRICHMENT MEANS [75] Inventors: Victor L. Hailstone, Chelmsford;

Ronald N. Harper, Rayleigh; Wilfred T. Oliver, Rugby, all of England [73] Assignee: Ford Motor Company, Dearborn,

Mich.

[22] Filed: June 5, 1972 [21] Appl. No.: 259,419

[30] Foreign Application Priority Data June 10, 1971 England 19867/71 [52] US. Cl. 261/44 R, 261/69 R [51] Int. Cl. F02m 1/14 [58] Field of Search. 261/69 R, 44 R, 390, DIG. 19, 261/410 [56] References Cited UNITED STATES PATENTS 1,444,222 2/1923 Trego 261/44 R 1,981,483 11/1934 Weber 261/44 R 2,208,864 7/1940 Farr r 26l/D1G. 19 3,246,886 4/1966 Goodyear et al. 261/390 3,282,572 11/1966 Karlovitz 261/62 Aug. 13, 1974 3,304,068 2/1967 Thomas 261/41 D 3,330,545 7/1967 Donovan 261/41 D FOREIGN PATENTS OR APPLICATIONS 30,368 10/1970 Japan 261/44 R 943,108 2/1949 France 261/44 R 152,442 10/1920 Great Britain 261/44 R 800,897 7/1936 France 261/D1G. 19

29,966 6/1919 Denmark 261/44 R 228,300 2/1925 Great Britain 261/44 R Primary E.raminerTim R. Miles Attorney, Agent, or Firml(. L. Zerschling; R. E. McCollum [5 7 ABSTRACT 10 Claims, 7 Drawing Figures AIR VALVE CARBURETOR WITH ENGINE STARTING FUEL ENRICIIMENT MEANS This invention relates to spark ignition internal combustion engines.

The carburetors of existing engines have a variety of devices that insure that sufficient fuel is supplied to all cylinders during start-up and idling conditions. These devices sometimes provide a richer fuel/air mixture than is actually required.

In an engine according to this invention: at engine idling speeds with the driver or operator controlled throttle closed, air flows at a velocity greater than Mach .6 through an aperture over a fuel jet in a carburetor; and downstream of the jet there is the sole starting enrichment device comprising:

a. a fuel outlet downstream of the jet;

b. a valve adapted to control the fuel outlet, urged by a spring into its open position, and movable by the vacuum in the induction system downstream of the jet into its closed position as soon as the engine starts; and,

c. means responsive to the position of the throttle to block communication between the outlet in (a) and the fuel supply before the pressure in the induction system reaches a value such that the spring in (b) opens the valve in (b).

The velocity of air flow preferable is Mach 1. The very high velocity of air flow over the jet ensures good vaporization and atomization of the fuel.

In existing engines different quantities of atomized as opposed to vaporized fuel are deposited on the walls of the inlet passages to the different cylinders. In other words, more fuel is deposited on the walls of the inlet passages to some cylinders than on the walls of the inlet passages to other cylinders. Consequently the former cylinders receive a weaker mixture than the latter cylinders. If the former cylinders are operating at the optimum fuel/air ratio, then the latter will be operating with too rich a mixture and the exhaust emissions from the latter will be noxious. This is particularly true during idle, warm up and transient conditions.

Since the high velocity produces better vaporization and atomization than hitherto, there is less deposit on the walls of the inlet passages and the effect of unequal deposits between the different cylinders on the fuel/air ratio is reduced. Consequently the average of the different fuel/air ratios supplied to the different cylinders may be reduced. The low velocity air flow over the jet before the engine has fired is, however, insufficient to provide a combustible mixture. The starting enrich ment device insures a combustible mixture.

The invention is hereinafter particularly described with reference to the accompanying drawings in which:

FIG. 1 is a cross-sectional, side elevational view on the axis of air flow through the carburetor;

FIG. 2 is a section on the line A-A in FIG. 1;

FIG. 3 is a section on the line BB in FIG. 1;

FIG. 4 is an elevational view of a detail, with parts broken away and in section, of part of the induction system; and,

FIGS. 5a, 5b and 5c are sections on the line CC in FIG. 4, illustrating a part in different operative position.

The drawings show the carburetor of an internal combustion engine and part of the induction system.

The induction system includes an inlet pipe 1 having a flange 2 bolted to a carburetor 3. The carburetor has a metal body which is rectangular in cross section (FIG. 2); at the bottom of the body there is a throat 5 and opposite the throat 5 is an opening 7.

A fuel pipe 9 is fixed in an aperture 11 in the throat 5, and constitutes a fuel jet 13. A tapered throttle or control needle projects into the jet 13 and is movable axially to control the size of the jet 13. The needle 15 is carried by an assembly 17.

The assembly 17 comprises a metal mounting plate or disk 19, which is fixed to the upper part of the body 3 around the opening 7. The plate 19 has two integral downwardly extending U-shaped walls 21. U-shaped members 23 made of a plastic material having a low coefficient of friction are located within the walls 21 and extend into a rectangular opening 25 in the plate 19. Channel shaped elements 27 also made of a plastic material having a low coefficient of friction line most of the long sides of the opening 25. Thus the edge of the opening 25 is lined by the U-shaped members 23 and by thechannel shaped elements 27 (FIG. 3).

A rectangular throttle slide 29 is slidable in the opening 25 and the U-shaped members 23, and is connected by a cable 31 to the engine throttle control. When the engine throttle control is closed, the throttle slide engages the throat 5. In this position the throttle slide blocks the induction air flow passage through the carburetor. The slide 29 has, however, an aperture 32 which communicates with the jet 13 and which when the throttle slide is closed constitutes the aperture through which the induction air flows.

The slide 29 has a cylindrical bore 33 which opens through a smaller central bore into the passage or aperture 32. The throttle needle 15 has a cylindrical portion 34 slidable in the bore 35 and a piston part 36 slidable in the cylinder 33. A spring 37 engages the piston part 36 to force the needle upwardly. The cylindrical core 33 communicates through an aperture 38 with the induction system downstream of the slide 29. When there is no vacuum in the induction system, the throttle needle is in its upper position in relation to the slide 29: in this position the minimum amount of the cylindrical portion 33 is in the passage 32. When there is a vacuum in the induction system, the atmospheric pressure acting on the upper side of the piston 36 forces the throttle needle 15 downwardly. This movement of thethrottle needle has two effects: it reduces the size of the fuel jet 13: and it reduces the size of the aperture 32. Consequently as the throttle needle 15 moves downwardly relatively to the closed throttle slide 29, the amounts of both air and fuel flowing to the engine are reduced.

The slide 29 is connected to the engine throttle by a dashpot arrangement 39. The piston part 36 has a bore 41 in which a plunger 43 is slidable. The cable 31 is connected to a nut which closes the upper end of the cylinder 33 in the slide 29, and the plunger 43 is connected by a wire 44 to the nut 45. The bore 41 is filled with oil. The nut 45 has a flange 47 which is engaged by a spring 49 compressed between the flange 47 and the end of a casing 51 bolted to the plate 19. The cable 31 extends through and is slidable in the upper end of the casing 51. The spring 49 thus biases the throttle slide towards the position shown.

The flange or spacer 2 has a fuel supply passage 52 connected to a passage 53 past a spring loaded ball check valve 55. The spring 57 of the valve biases the ball 55 of the valve towards the valve open position. The passage 53 communicates with a passage 54 (FIG. 5) in the body 3 of the carburetor; communication between the latter passage and the induction system is controlled by a valve plug 59. The valve plug is cylindrical and is rotatable in the body 3 of the carburetor. The plug has an axial passage 61, a radial passage 63 that may communicate with the passage 54 in the body 3, and a radial outlet passage 65 that constitutes the fuel outlet.

The plug is connected by a link 67 to the throttle slide 29. When the throttle slide 29 is in the closed position shown in FIG. 5a, the passage 54 in the body 3 communicates with the radial passage 63 so that fuel flows to the passage 65: as the slide 29 is opened the plug 59 is rotated to the positions shown in FIGS. 5b and SC to move the passage 54 out of register with the radial passage 63.

When the engine is stopped and the throttle slide 29 is closed, the check valve 55 (FIG. 3) is open and the needle valve is in its raised position in relation to the throttle slide 29. The only communication between the part of the induction system upstream of the throttle slide 29 and the part downstream of the slide is through the aperture 32 in the slide.

As the engine is cranked over before it tires, the vacuum in the induction system draws fuel through the outlet 65 and air and fuel through the passage 32.

As soon as the engine fires and begins to accelerate, the vacuum in the induction system increases. The rate of the spring 57 is such that the check valve 55 closes when the pressure in the induction system falls to a value such that the velocity of air flow through the aperture is Mach 1. This pressure is known as the critical pressure: when the pressure is greater than the critical value, the velocity through the aperture is less than Mach 1: when it is less than the critical value, the velocity through the aperture is Mach 1.

As the engine warms up with the throttle slide 29 closed, the internal friction decreases and so less power is required to overcome the internal friction. As aresult the engine speed increases. This increase in engine speed results in an increase in vacuum in the induction system and in the cylindrical bore 33 beneath the piston part 36 of the throttle needle. The throttle needle 15 therefore moves progressively downwards as the vacuum increases; this as explained above reduces the size of the fuel jet 13 and the size of the aperture 32,

' This reduces the power output of the engine so that engine speed remains fairly constant. The velocity of air flow over the jet remains at Mach 1.

When the engine throttle control is moved to increase the power output of the engine, the throttle slide 29 is moved upwardly. This moves the needle 15 upwardly as well. Consequently there is a gap between the bottom of the slide 29 and the throat so that the size of the air flow passage in the carburetor through which induction air flows is increased and the size of the fuel jet 13 is increased. As a result a greater mass of air enters the induction system and more fuel is supplied to the engine.

At a certain position of the throttle slide, the pressure in the induction system downstream of the jet rises above the critical value. Consequently the velocity of air flow over the jet falls below Mach 1. The quality of the mixture drops slightly as the air velocity falls but is nevertheless satisfactory.

The volume of the induction system downstream of the jet is at least three times and preferably about five times the swept volume of a single cylinder. This large volume of the induction system provides a reservoir of combustible mixture which reduces or possibly diminishes the need for special enrichment devices during acceleration.

When the throttle slide is about half open the vacuum in the induction system is such that the spring 57 is able to open the check valve 55. However by this time, the

slide 29 has by the link 67 rotated the plug 59 so that the passage 54 is no longer in register with the fuel outlet.

The starting and idling system described above can be applied as a self contained system to any known form of carburetor for example a fixed choke carburetor.

We claim:

1. An air valve type carburetor having an air/fuel induction passage open at one end to air at essentially atmospheric pressure and adapted to be connected to an engine intake manifold at the opposite end to be subject to the changing vacuum therein, a throttle valve slide variably movable across the passage between positions fully opening and closing the passage, a fuel jet opposite the slide subject to the flow of air therepast to induct fuel into the passage, a needle valve movably carried by the slide projecting into the fuel jet and means movable at times by engine vacuum to vary the fuel jet size as a function of changes in vacuum, the slide having an aperture therethrough communicating with the fuel jet and providing the sole supply of air to the engine during closed throttle valve engine shut off,

idle speed and deceleration operation, and engine starting fuel enrichment means operative when the engine is cranked to supply a starting fuel supply mixture to the engine, and rendered inoperative in response to the attainment of a predetermined engine vacuum to discontinue the fuel supply, a control valve in the line biased to an open position, the line having an outlet in the induction passage downstream of the slide, vacuum at a predetermined level corresponding to normal engine running operation acting on the control valve to block the line and terminate fuel flow, and other means operative at lower levels of vacuum forces indicative of engine acceleration modes to block the line and override the opening of the line by opening of the control valve.

2. A carburetor as in claim 1, the other'means comprising a second valve between the control valve and line outlet connected to the slide and movable to a position closing the line upon movement of the slide to an open throttle valve position indicative of engine accelerating operation.

3. A carburetor as in claim 1, the other means comprising a rotary valve in the line between its outlet and the control valve.

4. A carburetor as in claim 1, the aperture being so proportioned and dimensioned that the predetermined vacuum level to close the control valve is attained upon the attainment of a predetermined air velocity in a range between Mach 0.6 and 1.0 through the closed slide valve aperture.

5. A carburetor as in claim 3, including means pivotally connecting the second valve to the slide whereby movement of the slide to a predetermined open position rotates the second valve to a closed position to block the line.

6. A carburetor as in claim 5, the control valve comprising a ball valve, and spring means biasing the valve open.

7. A carburetor as in claim 5, in which the last mentioned means comprises a link.

8. An air valve type carburetor having an induction passage open to air at one end and to engine intake manifold vacuum at the opposite end and having a throttle valve movable across the passage between idle speed and wide open throttle positions respectively closing and opening the passage, a fuel jet containing fuel and opening into the passage adjacent to and cooperating with the throttle valve for induction of the main fuel supply thereinto by engine vacuum, and engine starting fuel supply means having a fuel outlet downstream of the throttle valve for supplying an engine start up supply of fuel, the fuel supply means including a fuel supply line having a control valve therein spring biased to open the line, and closed in response to engine vacuum acting thereon of a level indicative of normal engine running operation, and a second valve in the fuel supply line operable in response to a predetermined acclerative movement of the throttle valve to block the fuel supply line outlet regardless of the level of vacuum acting on the control valve.

9. An air valve type carburetor having an induction passage open to air at one end and to engine intake manifold vacuum at the opposite end and having a throttle valve movable across the passage between idle speed and wide open throttle positions respectively closing and opening the passage, a fuel jet containing fuel and opening into the passage adjacent to and cooperating with the throttle valve for induction of the main fuel supply thereinto by engine vacuum, and engine starting fuel supply means having a fuel outlet downstream of the throttle valve for supplying an engine start up supply of fuel, the fuel supply means including a fuel supply line having a control valve therein spring biased to open the line, and closed in response to engine vacuum acting thereon of a level indicative of normal engine running operation, and the control valve comprising a ball check valve, and a second valve mechanically operated in response to a predetermined opening of the throttle valve to block the fuel supply outlet regardless of the vacuum level acting on the control valve to prevent fuel flow through the supply line at all times after the throttle valve has moved from the closed throttle position.

10. A carburetor as in claim 9, the second valve comprising a rotary valve adjacent the fuel supply line outlet pivotally connected to the throttle valve whereby movement of the throttle valve to a predetermined open position indicative of engine vacuum levels lower than that needed to maintain the control valve closed rotates the second valve to close the fuel supply line outlet.

UNHED STATES PATENT @FFKCE CERTEFEQATE m QQRECTWN Patent No. 3, 9, 9 Dated August 13, 197 1 viator L. Hailstone et al itnventofls) u hove-identified patent It is certified that error appears in the a d as shown below:

and that said Letters Patent are hereby correcte Column 4, line 40, after continue the insert --starting fuel supply, the fuel enrichment means including" a line 10, after supply insert "line".

Signed and sealed this 18th ay of February 191 5a (SEAL) I Attest:

, C, MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officer and Trademarks FORM PC4050 (w'sg) USCOMM DC 60376 P69 US GOVERNMENT PRINTING OFFICE: i969 0--366-334

Claims

1. An air valve type carburetor having an air/fuel induction passage open at one end to air at essentially atmospheric pressure and adapted to be connected to an engine intake manifold at the opposite end to be subject to the changing vacuum therein, a throttle valve slide variably movable across the passage between positions fully opening and closing the passage, a fuel jet opposite the slide subject to the flow of air therepast to induct fuel into the passage, a needle valve movably carried by the slide projecting into the fuel jet and means movable at times by engine vacuum to vary the fuel jet size as a function of changes in vacuum, the slide having an aperture therethrough communicating with the fuel jet and providing the sole supply of air to the engine during closed throttle valve engine shut off, idle speed and deceleration operation, and engine starting fuel enrichment means operative when the engine is cranked to supply a starting fuel supply mixture to the engine, and rendered inoperative in response to the attainment of a predetermined engine vacuum to discontinue the fuel supply, a control valve in the line biased to an open position, the line having an outlet in the induction passage downstream of the slide, vacuum at a predetermined level corresponding to normal engine running operation acting on the control valve to block the line and terminate fuel flow, and other means operative at lower levels of vacuum forces indicative of engine acceleration modes to block the line and override the opening of the line by opening of the control valve.

2. A carburetor as in claim 1, the other means comprising a second valve between the control valve and line outlet connected to the slide and movable to a position closing the line upon movement of the slide to an open throttle valve position indicative of engine accelerating operation.