US3872851A

US3872851A - Fuel supply device for an internal combustion engine

Info

Publication number: US3872851A
Application number: US365057A
Authority: US
Inventors: Hirofumi Matsumoto; Masahiko Nakada
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 1972-07-19
Filing date: 1973-05-30
Publication date: 1975-03-25
Anticipated expiration: 1992-03-25
Also published as: JPS4928717A

Abstract

In providing a separate supply of fuel to an internal combustion engine when it is started up from a cold condition or as it idles following a cold start up, an additional supply of fuel is withdrawn from the engine carburetor float chamber and is passed through a valve operated fuel well into a fuel chamber. The fuel well is opened when the intake manifold of the engine is at atmospheric pressure for passing fuel into the fuel chamber. A fuel line connects the fuel chamber to the venturi tube for supplying fuel to the engine and a branch pipe, communicating with the fuel line, adds air to the fuel as it is directed into the venturi tube. The passage of fuel through the fuel line is discontinued in response to a temperature sensing arrangement which checks the engine temperature and, when a predetermined temperature level is reached, cuts off the flow through the fuel line to the venturi tube.

Description

States atet [191 Matsumoto et a1.

[ 1 Mar. 25, 1975 1 1 FUEL SUPPLY DEVICE FOR AN INTERNAL COMBUSTION ENG1NE [75] Inventors: l-lirofumi Matsumoto; Masahiko Nakada, both of Toyota, Aichi-ken, ap n .1 .s .1

[73] Assignee: Toyota Jidosha Kogyo Kahushilti Kaisha, Toyota, Aichi;ken,1apan [22] Filed: May 30, 1973 [21] Appl. No.: 365,057

[30] Foreign Application Priority Data July 19, 1972 Japan 47-71631 [52] U.S. Cl 123/180 R, 123/187.5 R, 261/39 D [51] Int. Cl. F02m 1/08 [58] Field of Search..... 123/179 6,179 A, 187.5 R,

123/180 R; 261/D1G. 8, 39 D United Kingdom 123/ 179 G Primary Examiner-Charles J. Myhre Assistant Examiner-W1 Rutledge, Jr.

Attorney, Agent, or Firm-Toren. McGeady and Stanger [57] ABSTRACT In providing a separate supply of fuel to an internal combustion engine when it is started up from a cold condition or as it idles following a cold start up, an additional supply of fuel is withdrawn from the engine carburetor float chamber and is passed through a valve operated fuel well into a fuel chamber. The fuel well is opened when the intake manifold of the engine is at atmospheric pressure for passing fuel into the fuel chamber. A fuel line connects the fuel chamber to the venturitube for supplying fuel to the engine and a branch pipe, communicating with the fuel line, adds air to the fuel as it is directed into the venturi tube. The passage of fuel through the fuel line is discontinued in response to a temperature sensing arrangement which checks the engine temperature and, when a predetermined temperature level is reached, cuts off the flow through the fuel line to the venturi tube.

6 C1aims, 2 Drawing Figures mEmmmzsmrs sum 1 OF 2 FIG;

FUEL SUPPLY DEVICE FOR AN INTERNAL COMBUSTION ENGINE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is directed to a device for reducing the amount of exhaust gases generated during the cold start up and idling following cold start up of an internal combustion engine equipped with an automatic choking mechanism.

2. Description of the Prior Art.

When an internal combustion engine is warming up, the rich air-fuel mixture supplied by the automatic choke gives off exhaust gases which have a greater carbon monoxide and hydrocarbon content than in the emissions from the engine when it is running at normal operating temperature. To reduce the proportions of such noxious components'from the exhaust, the automatic choking effect must be lessened and the choking time shortened. However, a lean mixture results and tends to cause difficulty in cold start up and to make idling unstable. Further, the use of a lean mixture may even increasethe volume of harmful exhaust emissions.

SUMMARY OF THE INVENTION Therefore, it is the primary object of the present invention, to eliminate the disadvantages experienced in the past by providing a device which provides a separate additional supply of fuel to the engine during cold start up and idling so that the engine has the same operating stability as when full use of the choke is made.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a schematic side view, partly in section, of one embodiment of the present invention; and

FIG. 2 is a schematic side view, similar to FIG. 1, of another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION For the sake of simplicity and clarity only the essential portions of the engine incorporating the present invention are shown in the drawings.

In FIG. 1, a carburetor l is arranged to supply fuel from a fuel chamber and to inject it by the well-known action of a venturi, not shown, into a venturi tube 3 with the resulting air-fuel .mixture being admitted, under the flow control of a throttle valve 4, into an internal combustion engine, not shown, via an intake manifold 5.

Between the float chamber 2 of the carburetor and the portion of the venturi tube 3 downstream of the throttle valve 4, an arrangement is provided for supplying additional fuel into the venturi tube during cold start up and idling of the engine. The arrangement consists ofa device for withdrawing fuel from the float chamber in dependence on the negative pressure or depression in the manifold, a conduit arrangement 30 for conveying fuel from the device 10 into the venturi tube by means of the suction action provided by the engine, and a device 40 for cutting off flow ofthetfuel through the conduit arrangement 30 when the operating temperature of the engine has risen to a pre-determined level.

The device 10 includes a fuel well 13 in communication with the float chamber 2 through a fuel intake pipe 11 and an air pipe 12. Within the fuel well 13, apiston 16 is displaceably positionable for regulating flow from the fuel well. A spring 14 biases the piston while a stopper 15, located above the inlet of the air pipe 12 into the fuel well, limits the downward movement of the p'iston. The piston 16 forms an upper space which is in communication with the intake manifold 5 through a manifold line 17. Adjacent its lower end, the fuel 'well has a valve seat 18 and a valve 20 is arranged for nor mally closing the valve seat and preventing flow out of the fuel well. A spring 19, having a weaker spring characteristic than the spring 14 acting on the piston, normally maintains the valve in the closed position. The lower end of the piston 16 contacts the upper end of the valve 20 for opening the valve ,when the piston is displaced downwardly. The lower end of the fuel well 13, normally closed by the valve 20, communicates through a fuel passage 21 with a fuel chamber 22. Flow from the fuel well enters the fuel chamber through its lower end. An orifice 23 is located at the opening into the lower end of the fuel chamber 22 and a check ball 24, shown floating on the level of the fuel in FIG. 1, seats in the orifice 23 when the fuel chamber is empty forming a closure for the opening from the lower end of the chamber.

When the intake manifold 5 is at atmospheric pressure, this pressure condition is conveyed through the line 17 into the fuel well above the piston 16 and, in combination with the spring, urges the piston downwardly'and opens the valve 20 against the action of the spring 19. With the valve 20 open fuel flows downwardly out of the fuel Well through-the passage 21 into the fuel chamber 22. On the other hand, if a vacuum exists within the intake chamber, the vacuum acts on the piston 16 within the upper end of the fuel well so that the piston is movedupwardly and the valve 20, under the biasing action of the spring, closes the valve seat and cuts off the flow of fuel into the fuel chamber 22.

The conduit arrangement 30 consists of a nozzle 31 connected to the portion of the venturi tube 3 downstream of the throttle valve, a supply passage 32 extending through the housing forming the fuel chamber from the lower end of the chamber to a point above the fuel level in the chamber and then changes direction and flows downwardly through the housing to a lower point where it is connected to a supply line 33 which is connected at its opposite end to the nozzle 31. Communicating with the upper part of the supply passage 32 is a passage 34 which supplies atmospheric air into .the supply passage and also supplies the air into the upper end of the fuel chamber. Due to the suction or drawing action of the engine, as it operates, the fuel is withdrawn from the fuel chamber through the fuel passage 32 where air, from the passage 34, is mixed with it so that the mixture then flows through the line 33 and the nozzle 31 into the venturi tube 3. When the fuel chamber has been emptied, the check ball 24 seats within the orifice 23 and closes the opening to the supply passage 32 and cuts off the flow of excess air.

The device 40 is made up of a casing 41 secured with its bottom in contact with the intake manifold 5 and an opening is provided in the casing which communicates its interior with the ambient atmosphere. Within the casing a valve 44 is supported on the end of an elongated bimetal member 42 which bends in response to the engine temperature within the intake manifold. The valve 44 is arranged to open or close a hole 43 in the casing and an air line 45 communicates between the hole 43 and the supply passage 32 at a point downstream from the point at which the branch passage 34 communicates with the supply passage. When the operating temperature of the engine is low, the bimetal member 42 positions the valve so that it closes the hole 43. As the operating temperature of the engine increases, the bimetal member 42 is gradually heated and assumes a bent configuration withdrawing the valve 44 from the hole 43 so that atmospheric air within the casing 41 flows through the air line 45 into the supply passage 32 and increases the pressure in the supply passage to an extent so that fuel is no longer withdrawn from the fuel chamber 22.

In view of the arrangement and function of the elements described above, fuel is supplied to the engine at cold start up and idling in the following manner. With the engine stopped and in a cold condition, and with the intake manifold at atmospheric pressure, the valve is opened and allows fuel from the float chamber 2 of the carburetor to flow through the fuel well 13 into the fuel chamber 22 up to the same fuel height or level as in the float chamber 2. With the engine at a temperature below the predetermined level, the device 40 maintains the valve 44 closed across the hole 43 so that seat 18 and discontinues flow of the fuel into the fuel chamber 22. In addition, the negative pressure conditions also act on the venturi tube 3 as well as on the fuel supply system. Consequently, additional fuel is continuously supplied to the engine through the conduit arrangement 30 until the fuel in the fuel chamber 22 is exhausted or the engine has warmed up to an extent that the predetermined level has been reached at which the bimetal member 42 displaces the valve 44 from the hole 43 in the casing 41. If the engine has already been warmed up, at start up the device prevents any additional flow of fuel from the fuel chamber 22 into the venturi tube 3. If the engine stalls because all of the fuel has been emptied from the fuel chamber 22 due to a comparatively extended warming-up period, the fuel chamber is replenished with fuel immediately after the engine stops. The fuel supply passage 32 and the air passage 34 are provided with orifices 35, and the duration and amount of fuel supply can be set, as desired, by modifying the diameter of the orifices and the capacity of the fuel chamber.

In FIG. 2 another embodiment of the invention is illustrated in which the valve mechanism of the device 10 and the temperature-sensing mechanism of the device 40 are modified. In the device of FIG. 2, a valve port 25 is located at the lower end of the fuel well in communication with the fuel passage 21. In the upper end ofthe fuel well, a diaphragm 27 forms a diaphragm chamber 28 above the level of the fuel in the well and a valve stem of a valve 26 which opens and closes the valve port 25 is secured to the diaphragm. Fuel for the float chamber 2 is withdrawn from a fuel tank 6 by a fuel pump 7 and is conveyed into the float chamber through a line 8. A branch connection in the line 8 extends into the diaphragm chamber 28 in the upper end of the fuel well. Thus, while the engine is running, the pressure in the line 8 acting within the diaphragm chamber 28 biases the valve 26 downwardly and closes the valve port so that flow of fuel to the fuel chamber 22 is cut off. If the pump is not operating the valve 26 is biased upwardly and fuel can flow through the passage 21 into the fuel chamber.

In FIG. 2, the device 40 includes a temperature sensor 46 arranged to detect the cooling water temperature within a water jacket 9 about the intake manifold 5. A solenoid valve is connected to the air line for regulating flow of atmospheric air into the air line. An electronic controller 48is connected to the temperature sensor 46 and to the solenoid valve. When the temperature of the cooling water in the jacket 9 is below a predetermined level the solenoid valve 47 closes off the line 45 and permits passage of the fuel from the fuel chamber into the venturi tube. However, when the cooling water has warmed up to a predetermined value, the temperature sensor signals the electronic controller which, in turn, directs a flow of current to the solenoid valve for positioning it in the open condition for admitting atmospheric air into the line 45. With these two differences in the embodiment of FIG. 2 as compared to that in FIG. 1, the remaining operation of the arrangement is the same as that described for the arrangement in FIG. 1. The

devices

10 and 40 in the two embodiments may be interchanged to provide a suitable combination.

As described above, the fuel supply system in accordance with the present invention, operates so that an extra or additional supply of fuel is accumulated while the engine is stopped, and only when the engine is started up and idling under cold conditions, the additional fuel is supplied together with air to the engine by the suction action in the venturi tube produced by the engine start up. The supply of the additional fuel is controlled in accordance with the temperature conditions of the engine, that is, either the temperature within the intake manifold or of the cooling water within the water jacket contacting the intake manifold. With the additional fuel supplied, the engine can run under stable conditions during warming up with little need for automatic choking. Additionally, it enables the engine to emit cleaner exhaust gases during the warming up period than has been the case in the past. Further, the embodiment illustrated in FIG. 2 can determine more precisely the engine conditions during warm up and, as a result, more accurately control the supply of the addi' tional fuel than is possible with the embodiment shown in FIG. 1.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. In an internal-combustion engine comprising a carburetor including a float chamber arranged to contain a supply of fuel, a venturi tube arranged to receive fuel from said float chamber, and an intake manifold arranged to convey the fuel from the venturi tube into the engine, wherein the improvement comprises first means for providing an additional fuel supply for cold start up and idling of the engine, said first means comprises a fuel well connected to said float chamber, a fuel chamber, a conduit connecting said fuel well to said fuel chamber for supplying fuel into said fuel chamber from said fuel well, a valve means for closing off flow from said fuel well through said conduit into said fuel chamber, and pressure means connected to said fuel well for acting on said valve means for opening flow between said fuel well and said fuel chamber when the engine is not operating and for closing flow between said fuel well and said fuel chamber when the engine is operating so that when the engine is inoperative a supply of fuel can be stored in said fuel chamber, second means for conveying fuel from said fuel chamber into said venturi tube, said second means comprising a fuel line connecting said fuel chamber and said venturi tube, and a branch pipe connected to said fuel line and said fuel chamber for introducing atmospheric air into said fuel line, and third means for sensing the temperature of the engine and being connected to said fuel line for discontinuing the flow of fuel therethrough from said fuel chamber to said venturi tube when the temperature of the engine reaches a predetermined level.

2. In an internal-combustion engine, as set forth in claim 1, wherein said fuel well has a valve port opening from its lower end into said conduit, said valve means arranged to open and close said valve port, said valve means comprises a valve located in said fuel well for normally maintaining said outlet closed, a piston arranged within said fuel well, and said pressure means comprising a passage connecting said fuel well to said intake manifold so that the pressure within said intake manifold acts on said piston for opening said valve port when said intake manifold is at atmospheric conditions and for closing said valve port when said intake manifold is at negative pressure conditions.

3. In an internal-combustion engine, as set forth in claim 1, wherein said third means comprises a casing in surface contact with said intake manifold, the interior of said casing being in communication with the atmosphere, a pipe line connecting said casing to said fuel line and said pipe line communicating with said fuel line at a location downstream from the connection of said branch pipe to said fuel line, a bimetal member positioned within said casing, a valve mounted on said bimetal member and arranged to maintain the opening closed when the engine temperature is below a predetermined level and to displace the valve from the opening when the engine temperature reaches a predetermined level for admitting air into said fuel line for discontinuing flow therethrough to said venturi tube.

4. In an internal-combustion engine, as set forth in claim 1, wherein said fuel well has an outlet from its lower end connected to said conduit, said valve means arranged to open and close said outlet, said valve means comprises a valve member including a valve stem extending upwardly from said valve member, a diaphragm extending across the upper end of said fuel well and dividing it into a lower fuel containing part and an upper diaphragm chamber, and said pressure means comprises a fuel tank, a pipe connecting said fuel tank to said float chamber, a pump for supplying fuel from said fuel tank to said fuel chamber, and a branch line from said pipe connected to said diaphragm chamber downstream from said pump so that the pressure in said pipe is supplied into said diaphragm chamber and when said pump is operating the pressure supplied into said diaphragm chamber depresses the valve downwardly into position for closing the outlet from said fuel well.

5. In an internal-combustion engine, as set forth in claim 1, wherein a waterjacket is provided about a portion of said manifold intake, said third means comprises a temperature sensor arranged to detect the water temperature within said water jacket, solenoid valve having an opening to the atmosphere, pipe line connecting said solenoid valve to said fuel line and said pipe line communicating with said fuel line at a location downstream from the connection of said branch pipe to said fuel line, said solenoid valve arranged to control flow into said pipe line, and an electronic controller connected to said temperature sensor and said solenoid valve so that said temperature sensor signals said electronic controller when the temperature of the water in the water jacket reaches a predetermined level and actuates said solenoid valve for admitting the flow of atmospheric air into said pipe line.

6. In an internal-combustion engine, as set forth in claim 1, wherein a fuel intake pipe extends between said float chamber and said fuel well and an air pipe located above said fuel intake pipe'extends between said float chamber and said fuel well, said fuel chamber having an opening in its lower end, said conduit connecting said fuel well to said fuel chamber is connected to the lower end of said fuel well and to the opening in the lower end of said fuel chamber, a floatable check ball located within said fuel chamber for closing off the opening to said conduit into said fuel chamber when fuel is emptied from said fuel chamber, said fuel line extending upwardly from said fuel chamber to its point of connection to said branch pipe and downwardly to said venturi tube, a first orifice located in said fuel line at the opening from said fuel chamber, and second oriflees located in said fuel line and in said branch pipe connected to said fuel line for regulating flow of air and

Claims

5. In an internal-combustion engine, as set forth in claim 1, wherein a water jacket is provided about a portion of said manifold intake, said third means comprises a temperature sensor arranged to detect the water temperature within said water jacket, solenoid valve having an opening to the atmosphere, pipe line connecting said solenoid valve to said fuel line and said pipe line communicating with said fuel line at a location downstream from the connection of said branch pipe to said fuel line, said solenoid valve arranged to control flow into said pipe line, and an electronic controller connected to said temperature sensor and said solenoid valve so that said temperature sensor signals said electronic controller when the temperature of the water in the water jacket reaches a predetermined level and actuates said solenoid valve for admitting the flow of atmospheric air into said pipe line.

6. In an internal-combustion engine, as set forth in claim 1, wherein a fuel intake pipe extends between said float chamber and said fuel well and an air pipe located above said fuel intake pipe extends between said float chamber and said fuel well, said fuel chamber having an opening in its lower end, said conduit connecting said fuel well to said fuel chamber is connected to the lower end of said fuel well and to the opening in the lower end of said fuel chamber, a floatable check ball located within said fuel chamber for closing off the opening to said conduit into said fuel chamber when fuel is emptied from said fuel chamber, said fuel line extending upwardly from said fuel chamber to its point of connection to said branch pipe and downwardly to said venturi tube, a first orifice located in said fuel line at the opening from said fuel chamber, and second orifices located in said fuel line and in said branch pipe connected to said fuel line for regulating flow of air and fuel therethrough.