US2151043A

US2151043A - Fuel feeding system for internal combustion engines

Info

Publication number: US2151043A
Application number: US739542A
Authority: US
Inventors: Clyde R Paton
Original assignee: Packard Motor Car Co
Current assignee: Packard Motor Car Co
Priority date: 1934-08-13
Filing date: 1934-08-13
Publication date: 1939-03-21
Anticipated expiration: 1956-03-21

Description

March 21, 1939. C, R, PATON y 2,151,043

, FUEL FEEDING SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed Aug. 13, 1954 viv ' HI v 3x1/vento@ CL2/DE E. FATUN UNITED STATES search PATENT OFFICE FUEL FEEDING SYSTEM FOR INTERNAL COMBUSTION ENGINES,

Clyde R. Paton, Birmingham, Mich., assignor to Packard Motor Car Company, Detroit, Mich., a corporation of Michigan Application August 13, 1934, Serial N0. 739,542

2 `Claims. (Cl. 15S-36.5)

This invention relates to internal combustion engines and more particularly to systems for supplying liquid fuel to an engine In the operation o-f an internal combustion engine, bubbles of fuel vapor often forminwthe liquid fuel in the feed line between the fuel tank. and the carburetor or form in theta-nkqand pass ,1 into said line especially in ,ht.weatherI\-These'I bubbles frequently produce avfvapor lock reducing the volume or previenting'the passage" of fuel through the line or through the carburetor nozzle, and causing the stopping of thef'engine. This tendency to form bubbls-ofmvapor in the fuel is increased if the fuel in the tank or in any part of the fuel feed line is under a pressure less than atmospheric. Vapor lock also occurs ln 'pressure feeding systems when the pressure therein drops to any appreciable extent below atmospheric pressure. Manufacturers of liquid fuels have recently been placing on the market more volatile fuels and the difficulty caused by vapor lock increases with an increase in the volatility of the fuel.

An object of the present invention is to produce a system for supplying liquid fuel from a storage tank to the carburetor of an internal combustion engine in which pressure limits are controlled to increase fuel feeding efciency under all fuel operating conditions.

In the operation of an internal combustion engine the fuel requirements of the engine Vary widely under different engine speeds and driving conditions. In the usual systems of feeding fuel from the fuel tank to the carburetor, the fuel is not fed under all conditions in proportion to the requirements of the engine. This results in unevenness in the running of the engine and in the power output therefrom.

The principal fuel feeding systems employed in moto-r vehicles are the gravity system, the vacuum system, the pressure system and the fuel pump system. The Igravity system requires the fuel tank to be placed above the carburetor which is contrary to present day practice in motor vehicle construction The vacuum system is unsatisfactory in that the available vacuum is usually lowest at the time when the demand for fuel is greatest, namely, when the engine is running at high speed with wide open throttle. The pressure system has the disadvantage that at certain times the pressure falls below that required for the proper feed of the fuel as when the engine is running at low speed or has been stopped for a considerable time. For this reason an auxiliary means for supplying pressure at such times such as a hand pump has been provided. In the fuel pump system, the pump often fails to feed the fuel as required by the engine when vapor is formed within the body of the fuel. The suction pump ordinarily provided in this system for feeding the fuel increases the formation of Vapor in the fuel during its passage to the carburetor by reducing the pressure.

Another object of the invention is to improve the construction and mode of operation of feeding systems for feeding the liquid fuel from the fuel tank to the carburetor of an internal combustion engine and to produce an eicient fuel feeding system which will avoid the disadvantages above pointed out in prior systems.

Another object of the invention is to prevent vapor being trapped in the supply tank of a motor vehicle fuel supply system.

A further object of the invention resides in the method of moving liqui-d fuel to an engine in a manner to eliminate vapor lock.

With the above and other objects in view the invention consists in the system for supplying fuel to the engine embodying the novel and improved features hereinafter described and particularly pointed out in the claims, the advantages of which will be readily understood by those skilled in the art.

The invention will be clearly understood from the accompanying drawing illustrating the invention in its preferred form and the following detailed description of the constructions therein shown.

In the drawing Fig. 1 is a View partly in side elevation and partly in vertical section illustrating an internal combustion engine provided with a system for supplying fuel to the carburetor embodying the present invention;

Fig. 2 is a detail view partly in front elevation and partly in vertical section illustrating certain parts of the system;

Fig. 3 is a plan View partly in section illustrating the fuel tank and certain associated parts shown in Fig. l;

Fig. 4 is a detail view in Vertical section partly broken away and taken substantially on the line 4-4 of Fig. 3, and

Fig. 5 is a detail sectional View illustrating a blow-off device for limiting the pressure in the fuel tank which may be employed in the presentI system.

The invention is illustrated in this application as applied to an internal combustion engine 2 having a carburetor 4 and a tank 6 for containing liquid fuel to be supplied to the carburetor. This tank is ventless except as hereinafter set forth and forms an air-tight chamber when the cap of the ller tube is applied.

The engine is provided with a fuel pump 8 of the so-called suction pump type acting directly on the fuel to pump the same from the fuel tank to the carburetor The pump comprises a chamber 9 connected by a pipe I8 with the fuel tank. This pipe is attached at I2 to the top of the fuel tank by an air-tight connection and passes downwardly into the tank to a point near the bottom thereof. The chamber 9 is connected by means of a pipe I4 with the carburetor.

The pump comprises a flexible diaphragm I6 secured at its margin between a peripheral ilange upon the cover I8 of the pump and the body or frame of the pump, said diaphragm constituting the lower wall of the chamber 9. A rod I9 mounted for longitudinal reciprocating movement in a guide 28 formed on the pump frame is secured at its upper end to the diaphragm I6, disks 2 I and 22 being mounted on each side of the central portion of the diaphragm to stiffen the same. The diaphragm is acted upon by a coiled spring 23 which, in expanding, moves the diaphragm in a direction to expel the liquid fuel from the chamber 9. The diaphragm is moved in the opposite direction against the action of the spring by mechanism comprising a lever 24 pivoted to the pump frame upon a pin 26 and having a pin and slot connection with the lower end of the rod I9- Said mechanism also comprises an oscillating lever 30 pivoted on the pin 26 and provided with an abutment 32 arranged to engage an abutment 34 on the lever 24. As the lever 38 swings in a clockwise direction, the abutment 32 on the lever is engaged with the abutment 34 on the lever 24 and the latter lever, the rod I9 and the diaphragm I6 are moved downwardly. As the lever 30 swings in the opposite direction, the diaphragm I6, the rod I9 and the lever 24 are moved upwardly therewith under the action of the spring 23. The pump 8 is provided with an inlet valve 36 a-nd with an outlet Valve 38. As the diaphragm I6 is moved downwardly by the downward movement of the rod I9 the valve 36 is opened to allow fuel to pass through the inlet pipe I8 into the chamber 9 and the outlet valve 38 is then closed. As the diaphragm is moved upwardly by the action of the spring 23 the inlet valve 36 is closed and the outlet valve 38 is opened, thereby allowing the liquid fuel to be forced by the diaphragm out of the chamber 9 and through the pipe I4 to the carburetor.

The engine is provided with an air pump 40 for pumping air into the liquid fuel tank 6 to increase the pressure of the air on the surface of the fuel above atmospheric pressure. The pump comprises a chamber 4I connected by a pipe 42 with the fuel tank 6. The pump is also provided with an inlet pipe 43 leading to said chamber and having a filter 43a at the outer end thereof to prevent the passage of dust and dirt intol the pump- The pump 40 is provided with a flexible diaphragm 44 constituting the upper wall of the chamber 44. This diaphragm is secured at its margin between a peripheral ange on the bottom section 45 of the pump and a corresponding flange on a hollow projection 46 on the pump frame. The diaphragm is acted upon by a coiled spring 41 which moves the same in a direction to expel the air from the chamber 4I. The mechanism for moving the diaphragm in the opposite direction comprises a rod 48 mounted for longitudinal reciprocating movement in a guide 49 on the pump frame, disks 50 and 52 being mounted in opposite sides of the central portion of the diaphragm to stiffen the same. Said mechanism also comprises a lever 54 pivoted on the pin 26 and having a pin and slot connection with the upper end of the rod 48. The lever 54 is provided with a projection having an abutment 55 arranged to be engaged by an abutment 56 on a projection on the lever 38 during the swinging movements of the latter lever in a counter-clockwise direction. As the lever 30 is swung in a counter-clockwise direction the abutment 56 on said lever is engaged with the abutment 55 on the lever 54 and the lever 54, the rod 48 and the diaphragm 44 are moved upwardly. As the lever 30 is swung in the reverse direction the diaphragm 44 is moved downwardly by the action of the coiled spring 41 and the rod 48 and lever 54 are moved downwardly therewith.

The pump 48 is provided with an air inlet valve 51 and with an air outlet valve 58. As the diaphragm 44 is moved upwardly by the upward movement of the rod 48, the valve 51 is opened to allow air to pass through the inlet pipe 43 into the chamber 4| and the valve 58 is closed. As the diaphragm 44 is moved in the opposite direction by the action of the spring 41, the valve 51 is closed and the valve 58 is opened, thereby allowing the air to pass from the pump through the pipe 42 into the space in the fuel tank above the fuel.

The mechanism for oscillating the lever 30 comprises a rod 60 mounted for longitudinal reciprocating movement in suitable guides, one end of which rod is engaged by said lever. The lever is held in engagement with the rod by a coiled spring 6 I. Said mechanism also comprises a cam 62 mounted on the cam shaft 64 of the engine and engaged by the other end of the rod.

'I'he mechanism above described is constructed and arranged to maintain a relatively low pressure, from two pounds to four pounds per squre inch, for example, upon the upper surface of the fuel within the fuel tank. This pressure will be transmitted to the fuel in the fuel feed line and will prevent formation of bubbles of fuel vapor in the fuel tank which might pass into the fuel feeding line and also the formation of such bubbles in the line itself.

Each of the pumps 8 and 40 is constructed so that the action of the pump is controlled by the pressure within the pump, the pumps tending respectively to maintain the fuel in the line between the pump 8 and the carburetor and the air in the fuel tank under substantially constant pressures. For example, as the pressure of the fuel in the pump 8 diminishes, the stroke of the diaphragm I6 under the action of the coiled spring 23 increases thereby increasing the rate of feed of the fuel to the carburetor. As the pressure of the fuel in the pump 8 increases, the stroke of the diaphragm I6 diminishes, because of the yielding of the spring 23 thereby diminishing the rate of feed of the fuel.

The pumpi 40 is controlled in a similar manner by the pressure of the air within the pump, the stroke of the diaphragm 44 increasing as the pressure of the air diminishes and the stroke of the diaphragm diminishing as the pressure of the air increases.

The air pressure above atmospheric applied to the surface of the fuel in the tank assists in feeding the fuel to the carburetor. The pumps 8 and 40 co-operate to feed a quantity of fuel at all times sulicient to meet the requirements of the engine under varying engine speeds and driving conditions. With a constant stroke of each of the diaphragms of the pumps 8 and 4l), the pumps will operate to cause a feeding of the fuel substantially in proportion to the feed of the engine. If an increase occurs in the rate of consumption of fuel in porportion to the speed of the engine, the pressure of the fuel in the fuel pump 8 is diminished and the stroke of the diaphragm I6 under the action of the spring 23 is increased to increase the rate at which the fuel is supplied to the carburetor. If a decrease occurs in the rate of consumption of fuel in proportion to the speed of the engine, the pressure of the fuel in the fuel pump 8 is increased and the stroke of the diaphragm I6 under the action of the spring 23 is diminished to diminish the rate at which the fuel is supplied to the carburetor. The pump 48 has a similar action, the stroke of the diaphragm 44 increasing to cause an increase in the rate of feed of the fuel when the rate of consumption of the fuel increases in proportion to the speed of the engine and the stroke of the diaphragm diminishing to cause a decrease in the rate of feed of the fuel when the rate of consumption of the fuel diminishes in proportion to the speed of the engine.

If the pressure above atmospheric, of the air on the surface of the fuel in the tank 6 is low, a relatively large proportion of the fuel feeding load is taken by the fuel pump 8. If the pressure within the fuel tank is atmospheric pressure, the fuel is fed to the carburetor to meet the requirements of the engine, by the fuel pump. If the pressure of the air on the surface of the fuel in the fuel tank is high, a relatively small proportion of the fuel feeding load is taken by the fuel pump 8. If the fuel pump 8 fails in its fuel feeding function, the fuel is fed in a reliable manner to meet the requirements of the engine by the air pressure within the tank 8 supplied by the pump 48.

Preferably the pump 8 and the pump 40 both act in co-operatiVe relation at all times in feeding the fuel. If desired the mechanism for supplying air pressure to the surface of the fuel in the fuel tank may be constructed to supply pressure sufficiently high to feed the fuel required when the engine is driven at moderate or high speeds, the fuel pump 8 then being thrown automaticaly Vout of operation by the high pressure. In such a construction the pump 8 is arranged to be thrown into operation when the air pressure furnished by said mechanism is relatively low, as upon starting the engine and when running at low speeds, and will supply all or part of the fuel required for the operation of the engine at such times.

TheY engine is preferably provided with means for preventing the pressure in the fuel tank from increasing beyond a predetermined maximum. In the present construction this means consists of an automatic blow-olf device built into the cap for the filler tube. In the illustrated construction the engine is provided with a ller tube 66 having a cap 68. This cap is constructed to be threaded upon the upper end of the ller tube and comprises a body 10 having a central chamber 12 and a series of passages 14 leading from said chamber to the periphery of the cap. Secured to the cap within the chamber 12 by means of a bolt 16 is a disk 18 having a number of openings 80, said disk engaging a suitable shoulder on the cap. A valve member 82 is slidably mounted upon the bolt 16 within the chamber 12 and is provided with an annular projection 83 arranged to engage the portion of the disk 18 radially outside of the openings 88. The member 82 is acted upon by a coiled spring 84 which maintains the same normally in engagement with the disk 18.

When the cap 10 is applied to the ller tube 66 and screwed down so as to form a tight connection between the same and the tube, the cap will prevent the leakage of air from the tube until the pressure reaches a predetermined maximum. When a pressure is reached suflicient to overcome the tension of the spring 84, the member 82 is lifted out of contact with the disk 18 allowing the air within the fuel tank to pass outwardly through the openings 80 in the disk 18 and between said disk and the valve member 82 into the chamber 12 and from which it escapes through the passages 14.

In the event the pump 48 fails or when pressure in the supply tank falls below atmosphericl pressure when the engine is not operating due to a temperature drop or other causes, there will be a pressure drop in line 42 which will unseat valves 58 and 51 and thereby connect the interior of the tank with atmosphere. The pressure in the tank will thus return to atmospheric pressure and the pump in the fuel feeding system will function efficiently. This arrangement of venting will therefore establish the limit to which pressure in the system can drop below atmospheric pressure, this limit being established by the pressure required to compress the spring seating valves 51 and 58, which pressure is slight. The

. pressure relief valve 83 controls the high limit of pressure in the fuel feeding system. Due to these high and low pressure controls, pressure in the system is established in a range wherein fuel feeding efficiency is maintained under all normal fuel operating conditions.

The usual liquid fuel tank has a filler tube located at one end of the tank and in the rear portion of the upper wall. If the vehicle is standing upon an inclined roadway, this may cause a trapping of air in a portion of the tank remote from the filler cap and this portion of the tank cannot be filled. To avoid this objection means is provided in the present construction for venting the forward portion of the liquid fuel tank substantially midway between its ends.

In the construction shown, the tube 42 is connected with the fuel tank by means of a fitting 86 having a passage 88 therein leading from the end of the tube to the space within the fuel tank. The fitting 86 is also provided with a transverse passage 90 which is connected by means of a pipe 92, having its ends secured respectively in the fitting 86 and in the filler tube 66, with a passage 94 in the filler tube. The upper end of the passage 94, when the cap 68 is attached to the ller tube, is sealed by means of an annular contact surface 95 formed on the inside of the filler cap.

With this construction when the filler cap is removed the tank will be vented as usual at the opening in the ller tube and the central forward portion of the tank will also be vented through the passage 88 and 96, the tube 92 and the passage 94.

While, in the present embodiment of the invention, means is provided for introducing air into the fuel tank to increase the pressure above s.. s i

eeaftil atmospheric, it is to be understood that the invention is not limited to producing the increased pressure by the introduction of air but that the invention may be embodied in constructions in which the pressure in the tank is increased by the pumping or otherwise introducing of some other gas or vapor into the tank.

It is to be understood that the invention is not limited to the particular construction and arrangement of parts of the illustrated embodiment of the invention, but that the construction shown and described is merely illustrative of the invention and that the invention may be embodied in other forms within the scope of the claims.

Having explained the nature and object of the invention and having specifically described a construction embodying the invention in its preferred form, What is claimed is:

l. A method of moving liquid fuel in. a fuel supply system for an engine including a source of supply having a normally sealed opening exposed to unconned atmosphere, comprising moving a column of fuel from the source of supply under vacuum, delivering said column to said engine under pressure, applying pressure to the source of supply to remove vapor lock from and supplement the said delivery of said column, and venting said pressure exclusive of said source of supply through the normally sealed opening when said opening is unsealed upon occasion to replenish said source of supply.

2. In combination With an internal combustion engine and a fuel tank with a normally sealed filler opening, a fuel system comprising means for drawing fuel from said tank under vacuum and delivering the fuel to said engine under pressure, means for providing a pressure on the fuel in said tank Within a predetermined range including atmospheric pressure for preventing Vapor lock in said first means, and means interconnecting said second means and said opening independent of said tank whereby the pressure developed by said second means is vented through said opening when unsealed upon occasion to replenish said tank.

CLYDE R. PATON.