US2920690A

US2920690A - Pressure-regulated fuel supply system

Info

Publication number: US2920690A
Application number: US460659A
Authority: US
Inventors: George W Wright
Original assignee: Tokheim Corp
Current assignee: Tokheim Corp
Priority date: 1954-10-06
Filing date: 1954-10-06
Publication date: 1960-01-12
Anticipated expiration: 1977-01-12

Description

Jan. 12, 1960 ca. w. WRIGHT 2,920,690

PRESSURE-REGULATED FUEL SUPPLY SYSTEM Filed Oct. 6, 1954 4 Sheets-Sheet 1 INV TOR. Geo no: lf if /am;

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4 Sheets-Sheet 2 INVENTOR.

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e. w. WRIGHT PRESSURE-REGULATED FUEL SUPPLY SYSTEM Jan. 12,1960

Filed Oct. 6, 1954 6 n L Wm M a n m n a w w 1/2 Jan. 12, 1960 Filed Oct. 6. 1954 G. W. WR\GHT FRESSURE-REGULATBD FUEL SUPPLY SYSTEM 4 Sheets-Sheet 4 INVENTOR- United States Patent PRESSURE-REGULA'IED FUEL SUPPLY SYSTEM George W. Wright, Fort Wayne, Ind., assignor to Tokil-eim Corporation, Fort Wayne, Ind., a corporation of Application Octoher 6, 1954, Serial No. 460,659

1 Claim. 01. Isa-36.3)

This invention relates to a fuel supply system, as for supplying fuel from a vehicle tank to the fuel-mixing device of the internal combustion engine by which the vehicle is powered; in which the fuel is conveyed under high pressure from the tank to a point immediately ahead of the fuel-mixing device of the engine, but is delivered to the fuel-mixing device at a regulated pressure; and which system is adapted for use with a mixing device of any type suitable to the operation of the engine. By fuel-mixing" device, I mean any device by which fuel is fed to or in the engine, including a carburetor, a fuel injector, or other device for a similar purpose.

The general purpose of this invention is to provide a fuel supply system which will eliminate vapor lock difliculties, vapor lock being defined as a failure of the supply system to supply fuel at a proper rate and in a proper state to maintain the engine in operation and which arises by reason of the presence of vapor or air in the fuel-supply system, whether such vapor or air occurs as free gas or is dissolved or absorbed in the fuel. The vapor lock difficulties which it is the object of the invention to avoid include those which arise from the presence of either free or absorbed gas in the fuel system or from the liberation of absorbed gas at any point in the system, as in the carburetor float chamber; those which arise from the existence of undesired or improper pressure conditions such as may result from uncontrolled vapor pressure in the system; those which arise from improper fuel feed rates, such as reduced rates resulting from the feeding of free gas in or to the fuel-mixing device or from the presence of free gas in the fuel pump, and increased rates resulting from high fuel pressures in the system or from failure of carburetor control valves. It is an object of the invention to avoid heat vaporization of fuel in the system, under even extreme high temperature conditions. It is a further object of the invention to avoid fuel waste, such as may occur through excessive venting provisions which have been employed to minimize vapor lock difiiculties in other systems; and to avoid difficulties which may arise from the dilution or reduction of engine intake air as the result of venting vaporized fuel to air intake passages. It is a further object of the invention to provide an eflicient fuel supply system and apparatus of reliable construction and adapted for use on various vehicles and with various engines and fuel-mixing devices, and thus to permit standardization of fuel-supply apparatus, as for military and fleet use. It is a further object of the invention to provide a fuelsupply system and apparatus which will operate efiiciently and reliably, and avoid vapor lock diflicultics, under various and extreme operating conditions.

In accordance with the invention, the fuel is desirably contained in a vented fuel tank, at atmospheric pressure, so that as received by the conveying system it will contain no dissolved or absorbed gas-either fuel vapor or air-by reason of an elevated storage pressure. Fuel is forced through the system by a submerged pump, such as a centrifugal pump mounted near the bottom of the 2,920,690 Patented Jan. 12, 1960 fuel tank. Gas-separation means is desirably associated with the pump to insure that the pump delivers fuel as free as possible from entrained or absorbed gas. The pump normally maintains a high delivery pressure throughout the fuel line, up to a point at or close to the fuel-mixing device of the engine, and is connected to the fuel line through a check valve, to insure that the fuel line will remain full of liquid, and desirably under pressure, even when the centrifugal pump is stopped. The fuel line may contain an accumulator, at a point downstream from the check valve, to assistv in maintaining the line under pressure and to hold a reserve supply of fuel under pressure to maintain flow during any temporary periods of inadequate output of the pump.

At the delivery end of the fuel line, the fuel is passed through a pressure and flow regulator which, when: the system is connected to a low-pressure fuel mixing device such as a carburetor, will regulate the fuel-delivery pressure within predetermined limits under all conditions, and will provide adequate flow at that pressure to meet any demand. The regulator maybe locked open to pass flow at full line-pressure to a fuel mixing device. such as a fuel injector which requires fuel to be supplied to it at a higher pressure- The system, desirably includes a filter, which may be of conventional construction and is preferably located in the fuel-supply line upstream from the pressure regulator.

The pump, the check valve, and the accumulator if one is used, are desirably associated in a sub-assembly mounted at the fuel tank. The filter and the pressure and flow regulator are. desirably mounted together in the engine compartment of the. vehicle, and the regulator is desirably located. close. to the fuel-mixing device of, the engine so there is a minimum length of fuel line, between the. regulator and that fuel-mixing device.

The accompanying drawings illustrate the invention. In such drawings:

Fig. 1 is a somewhat schematic view of a fuel-supply system embodying the invention;

Fig. 2 is. a vertical section of the sub-assembly shown in Fig.1 as mounted in the fuel tank and which includes the motor and pump, the check valve, and the accumulator;

Fig. 3 is a top plan view of the sub-assembly shown in Fig. 2, with parts broken away to show the outlet passage from the accumulator;

Fig. 4 is a vertical section taken on the line 4-4 of Fig. 3;

Fig. 5 is a vertical section of a modified tank header for use when the pump is directly connected to the fuel line and the accumulator is omitted.

Fig. 6 is a vertical section of the pressure and flow regulator; and

Fig. 7 is a bottom plan view of the pump rotor, with its enclosing plate removed, taken on the line 77 of Fig. 2.

In the apparatus shown in Fig. 1, the fuel is contained in a tank 10 which may be provided with a sump 12 to receive the inlet 14 of the pump 16. The pump 16 and its motor 18 are desirably directly connected to form a submerged unit, and that unit is supported in the tank 10 from a mounting plate 20 mounted at the top of the tank 10. The assembly associated with the mounting plate 20 contains a check valve (shown in Fig. 2) and an accumulator 22.. The fuel outlet fitting 24 from this sub-assembly is connected to a supply pipe 26 desirably leading from the tank location to the engine compartment of the vehicle. In that compartment it is connected to the filter 2'8, and this, in turn, is connected by a pipe 30 to the pressure and flow regulator 32. The regulator 32 is positioned close to the fuelmixing device of the engine, here shown schematically as a carburetor 34, and the regulator is connected to the carburetor by a short pipe 36. Fuel is admitted to the carburetor through a carburetor feed-control valve 38, here shown as a needle-type valve closing against flow and controlled by a float 39 housed in the float chamber 40 of the carburetor 34.

The pump motor is energized by a supply wire 42 connected to the battery of the vehicle through the engine-controlling switch of the vehicle, and the pump motor is thus energized whenever that engine switch is turned on.

The sub-assembly mounted at the tank 10, as shown inFig. 2, comprises the mounting plate 20, which carnes a depending cylindrical sleeve 44 by which the motor .18 and pump 16 unit is supported at the bottom of the tank 10. The motor is provided with its own housing and frame, and is secured by screws 49 to a flanged mounting collar 46, which is secured against the lower end of the sleeve 44 and to the mounting plate 20 by a series of circumferentially spaced tie bolts 48. The motor is disposed vertically, with its shaft 50 projecting downwardly, and the pump rotor 52 is mounted directly on the downwardly projecting end of the shaft 50. The pump housing comprises an upper casing 54 secured to the lower end of the collar 46 by the screws '49, and a lower housing 56 assembled to the upper housing 54. A shroud 58 secured to the bottom of the lower housing 56 forms a large inlet opening 60 to the pump and carries a relatively coarse-mesh inlet screen 62 adapted to mechanically protect the pump against the entrance of large SOlldS, but to present no obstruction to the entrance of the fuel or to the fine dirt which is to be removed by the filter 28.

The pump rotor 52 is formed as an assembly of a casting and a cover plate 66. The casting comprises a central mounting hub 63 and an outer annulus 64 which carries radial-flow main blades 72 on its bottom surface. The annulus 64 is spaced from the huband supported therefrom by a set of axial-flow blades 78. The cover plate 66 is secured against the lower ends of the blades 72, and has a depending cylindrical neck 68 which is telescopically received about the inner wall of the shroud 58 and rides against a sealing ring 70, desirably of felt material, carried by the pump housing. The annulus 64 and cover plate 66 form a main pump. This is a radial-flow pump, and discharges to a volute chamber 74 leading to an upward outlet in communication with a pump delivery pipe 76.

The axial-flow pump blades 78 of the pump rotor receive liquid from the same inlet opening 60 as the main pump blades 72, and discharge upward toward the motor to an outlet chamber 80, which is vented through relatively large passages 82 back to the tank. Desirably, the outer ends of the outlet passages 82 are covered by a coarse screen 84 wrapped about the cylindrical outer surface of the collar 46. The annulus 64 of the rotor 52 forms an upwardly extending rim 86 about the axialflow impeller blades 78, and the outer surface of this rim 86 rides against a sealing member 88 carried in a slot between the pump housing 54 and the collar 46, and which is desirably of felt material.

The volute chamber 74 communicates by way of the clearance between the pump rotor 52 and the housing 54 with one or more passages 90 drilled in the housing 54 and the collar 46 and leading to the interior of the motor 18. A small by-pass fiow of gasoline is pumped through these passages 90, to lubricate the moving parts and the bearings of that motor 18. The upper end of the motor is provided with a short outlet pipe 92, through which the lubricating flow of gasoline is discharged to the space within the mounting sleeve 44. That sleeve 44 is substantially *imperforate and closed below the level of the lubricant discharge pipe 92, but is provided with openings 94 at or above the level of that discharge pipe. With this arrangement, the-lubricant flow also serves to cool the motor 18, and a body of cooling liquid is normally retained within the mounting sleeve 44 below the level of the openings 94 at all times.

The pump rotor is desirably driven by the motor at a speed of about 3600 rpm. Its combination of a radialflow main pump and a central axial-flow by-pass pump tends to ensure that the liquid discharged to the volute 74 will contain a minimum of dissolved or entrained gas. In the inlet chamber of the pump, the rotation of the pump produces a swirl in the entering liquid, which tends to separate gas from the liquid and cause that'gas to move to the center of the swirling body of liquid, leaving relatively gas free liquid at the outer portions of that swirling body of liquid. The center portion of the liquid stream, containnig any gas present in the inlet liquid, enters the axial-flow pump formed by the blades 78 and is discharged back to the tank through the discharge passages 82. The relatively gasfree liquid at the periphery of the entering stream is received by the radialflow pump formed by the blades 72, and it is this relatively gas-free liquid which is discharged to the volute 74.

To facilitate the discharge of gas from the center of the inlet stream, the motor shaft 50 may be made hollow, to provide a gas-escape passage 51 at the axis of the inlet stream.

The relatively gas-free liquid is carried upward from the volute 74 through the pump delivery pipe 76 to a chamber formed between the mounting plate 20 and a bottom cover plate 102. In this chamber the liquid flows laterally to a check valve 104 which opens with flow from that chamber 100. The valve 104 conveniently comprises a poppet-type valve member 106 whose stem is guided in a spider 108 mounted in an opening in the bottom wall 110 of the mounting plate 20. The valve member v106 is spring pressed downwardly, and its head seats against the edges of an opening in a plate 112 secured and sealed against the bottom face of the wall 110.

Above the wall 110, the cover plate is formed to providea cylinder 114 for an accumulator piston 116 comprising a pair of disks clamped against a downwardly cupped piston leather 118. The piston 116 is guided by a stem 120 which rides in a bore 122 carried by a cover plate 124, and is urged downward by a spring 126. The cylinder 114 below the piston 116 forms an accumulator chamber 128, which is connected to the outlet elbow 24 and its connected line 26 through a passage 130 defined by depending walls 132 formed as part of the cover plate 20. As shown in Figs. 3 and 4, this passage 130 communicates with the accumulator chamber both through its bottom wall 110 and through an opening 131 cut in the wall of the cylinder 1 14 at the bottom of that cylinder. The space above the piston 116 within the cylinder 114 and cover 124 is vented to the tank 10 by a passage 125 formed in the header 20.

Flow from the pump through the valve 104 is to the accumulator chamber 128 below the piston 116. As pressure builds up in the system from operation of the pump 16, the piston 116 is moved upward against its spring pressure, and the accumulator space 128 is enlarged. The force of the spring 126 on the piston 116 maintains pressure on the fluid in the accumulator cham ber 128 and in the downstream line therefrom, and the chamber contains a reserve body of liquid under pressure. Under normal conditions this reserve supply of liquid under pressure will not be needed, but its presence will assure engine operation under a number of abnormal conditions which may arise. For example, upon initial closing of the vehicle engine switch, the initial operation of the pump may not provide suflicient flow and pressure to insure the immediate operation of the engine, and the reserve supply of liquid in the accumulator supplements the pump output untilthe pump has reached full operating capacity, Similarly, if the fuel level of the tank is low, the movements of the vehicle may momentarily move the fuel away from the inlet of the pump, so that the output of the pump will momentarily decrease, and under these conditions the reserve supply of liquid in the accumulator chamber will maintain the fuel supply to the fuel-mixing device until the pump again receives full inlet flow. Still other abnormal conditions may arise under extreme operating conditions.

The motor-supply circuit is of the usual automotive type, with one side grounded. The other side is supplied through a lead wire -42 connected at the upper end of the motor supporting assembly to an insulated pin 134 extending through the bottom wall of the plate 102. The upper end of :such pin is connected by a ire 1236 to a similar insulated connector 138 carried by the top wall of the plate '20, and the top of this pin 138 is. connected to the engine switch by a suitable wire which is not shown.

The fuel line formed in part by the pipe 26 leads from the sub-assembly mounted at the tank 10 to the engine compartment of the vehicle. Here, it desirably includes the filter 28 which, as pointed out above, may be of any known construction suitable for the filtration of the fuel being used. The filter 28 is connected by a pipe 30 to the pressure regulator 32, which is shown in detail in Fig. 6. and the regulator 32 is connected by a short pipe or nipple to the fuel-mixing device of the engine, here a carburetor 34.

The regulator comprises a valve body 140 having an inlet 142 and an outlet 144 separated by a wall 146 which forms the seat 148 for the main valve 150. The valve 150has a downwardly extending stem 152 whose lower end carries a piston 154, desirably formed as a heavy felt washer, and which rides in a dash-pot cylinder 156 formed in the bottom cover plate 158 for the valve body 140. The valve 150 is a flow-regulating valve, and not only carries a sealing valve-face 160, but the depending stem 152 has an enlarged upper end which rides in the valve bore and which terminates at its lower end in a conical shoulder 162. The valve 150 and the shoulder 162 co-operate with the valve bore and seat 148 to regulate flow through the valve. The valve 150 is controlled by a diaphragm 164, whose central piston portion 166 is rigidly secured to the upwardly extending stem of the valve. The diaphragm is clamped between the valve body 140 and a casing member 168 which forms a pressure chamber 170 above the diaphragm 164. The diaphragm and the valve 150 are pressed toward closed position by a light spring 172.

A plate 174 mounted above the housing 168 forms a by-pass chamber 176 and provides a valve port 178 leading from the chamber -176 to a control-diaphragm chamher 180. The diaphragm chamber 180 is closed by a diaphragm 182 clamped at its edges between the plate 174 and a cover 184 which forms a housing for a calibrated spring 186 which presses the diaphragm 182 downward. The spring housing is vented to the atmosphere through a vent opening 188. The diaphragm 182 carries a by-pass valve 190 which closes in the direction of flow through the port 178 from the by-pass chamber 176.

The inlet 142 to the main valve 150 connects through a restricted orifice 192 in the valve body 140, and through a bore 194 in the housing 168, with the by-pass chamber 176, which connects through the valve port 178 with the diaphragm chamber 180. This chamber 180 connects through a passage 196 in the valve plate 174 and a passage 198 in the casing 168 with the outlet of the valve body 140. Communication between the diaphragm chamber 180 and the outlet chamber 145 is relatively free, to permit outlet pressure at the outlet 144 to exert itself on the diaphragm 182. The by-pass chamber 176 communicates with the main diaphragm chamber 170 through a restricted opening 171, so that 6 the pressure drop in the by-pass controls the pressure in that main diaphragm chamber 170.

It is desirable that a fuel-supply system containing a pressure regulator as shown inFig. 6 should be adaptable to different engine installations in the same vehicle. The engine of the vehicle may be changed, either by replacement or modification, from say a carburetor-equipped engine which requires a low-pressure fuel supply to say a fuel-injector engine which requires a fuel supply under high pressure. It is therefore desirable that the fuel regulator be capable of being locked in open position. To this end, the lower end of the dash-pot cylinder 156 is provided with a plunger 157 which may be left retracted as shown in Fig. 6 during normal operation of the regulator, but which may be raised and locked in raised position, as by screw threads, to hold the main valve of the regulator in open position.

From the regulator 32, fuel is supplied under regulated flow and pressure to the carburetor 34. Carburetor-float valves, such as the valve 38 shown in Fig. 1, are commonly designed for operation with a maximum fuel-inlet pressure of about 5 pounds. Tests of fuel-supply systems show that carburetor-float valves are erratic and unreliable inoperation, especially if the carburetor-inlet pressure is allowed to exceed 5 pounds pressure. It is important, therefore, to maintain the inlet pressure to the carburetor at or below a predetermined maximum pressure, such as the 5 pound pressure for which carburetors are commonly designed. I deem it important that pressures exceeding this maximum pressure be rigorously avoided under all conditions to which the system is subjected, both operating conditions and conditions when the system is not in operation.

With fuel-injector engines, the injector not only requires a relatively high-pressure fuel supply, but there is normally no means such as a vented float chamber in which gas can separate from the fuel, and it is therefore especially desirable that the fuel supplied to the injector be as free as possible from free or absorbed gas.

I desirably convey fuel through the fuel line to the pressure regulator at a pump discharge pressure of say 16 to 22 pounds per square inch, and for illustrative purposes, a line pressure of 20 pounds may be considered normal. With suitably calibrated springs, the pressure regulator shown in Fig. 6 willmaintain the delivery pressure to the carburetor accurately between relatively narrow limits, say between a minimum of 3 pounds per square inch and a'maximumm of 5 pounds per square inch.

The main valve 150 is urged toward open position by line pressure acting on the bottom of the valve and by discharge pressure acting on the bottom of the main diaphragm 166, and while discharge pressure also acts on the valve itself in a valve-closing direction, the net result of these forces tends to open the valve. This opening tendency is opposed in part by the light spring 172, but is mainly opposed by the pressure in the main diaphragm chamber 170. This pressure in the chamber is controlled to regulate the position of the main valve 150. Such control is exerted by conditions in the by-pass at the .point where the chamber 17 0 communicates with the by-pass through the restricted opening 171. These conditions depend on the restriction of the orifice 192 and on the position of the valve 190, and the position of such valve depends on the pressure differential across the by-pass diaphragm 182. Since this differential is that between discharge pressure and atmospheric pressure, it is substantially independent of line pressure, and the regulator will therefore give a discharge pressure which remains within the desired limits under all conditions.

Under flow conditions, the by-pass valve will be open to an extent determined by discharge pressure, and flow will occur through the by -pass. The opening through the valve port 178 of that valve 190 will be larger than the restricted orifice 192 at the inlet end of the by-pass,

7 with the result that a pressure drop will occur in'the by-pass to reduce the pressure at the passage 171 conmeeting the by-p'ass wit'h the main diaphragm chamber 170. The passage 171 is restricted, but is desirably somewhat larger than the restriction 192. The reduced pressure in the by-pass will cause a corresponding reduced pressure in the control chamber 170. This will reduce the valve-closing force exerted by that pressure on the main diaphragm 166, and the main valve 150 will be open 'to the extent necessary to supply the carburetor demand at the regulator-discharge pressure.

If the demand falls ofi and the carburetor-float valve moves toward closed position, the pressure in the regulator outlet will rise, the by-pass valve will inconsequence move toward closed position, the by-pass outlet will be restricted, and the pressure drop in the by-pass will be less. The pressure in the by-pass at the point of its communication with the main diaphragm chamber 170 will be higher, and that higher pressure will correspondingly raise the pressure in that chamber'170 and increase the valve-closing force of the main diaphragm 166. The main valve 150 will accordingly move in a closing direction, to the position which delivers the required flow and maintains the discharge pressure within the predetermined limits. 1

If the carburetor demand increases, the regulator responds in a corresponding manner, to open the 'by-pass valve, increase the by-pass pressure drop, decrease the pressure in the control chamber 170,and open the main valve 150 by an amount suitable to supply the increased demand while maintaining the regulator outlet pressure within the predetermined limits.

At very low flow conditions through the carburetor, the whole demand may be met by flow through the bypass, without producing a pressure drop between the restricted orifice 192 and the valve 190 sulficient to cause the main valve to open.

When the carburetor-float valve closes, the consequent pressure rise in the regulator outlet immediately causes the by-pass valve 190 to close. Full line pressure then occurs in the by-pass upstream from that valve, and this high pressure is transmitted to the main diaphragm chamber 170, where it causes the main diaphragm 166 to exert a strong valve-closing force. closes and is positively held closed by line pressure until demand conditions again open the by-pass valve to produce flow conditions as described above.

Under these varying conditions, the pressure in the main control chamber 170 varies between a maximum equal to full line pressure of say 20 p.s.i. and a F The main valve which is but little above the outlet pressure of say 5 p.s.i. This wide range of pressure is utilized to control the main valve, while the discharge pressure remains within narrow limits of say 3%. to 5 psi.

The by-pass valve, being required to handle but small amounts of flow, is readily controlled in response to small pressure changes in the regulator outlet, and its control of the main valve makes the regulator highly responsive to the outlet pressure.

The restriction of the passage 171 tends to retard flow to and from the main diaphragm chamber 170, and hence to retard movements of the valve 150. Movements of the valve 150 are also dampened by the dash-pot action of the piston 154 in its dash-pot cylinder 156. Smooth operation is thus obtained, without hunting or fluttering of the main valve.

The regulator is effective at all flow ratesfull flow, intermediate flows, and no flow-to exert a full regulating action in response to outlet pressure, and to ensure that the carburetor valve is never subjected to a pressure greater than the predetermined regulated pressure of say 5 pounds per square inch.

The over-all operation of the fuel-supply system to a carburetor engine is as follows:

With the system at rest after a previous period of operation, the fuel line will be full of fuel under pressure, from the check valve 104, through the accumulator chamber 128, its outlet passage 130, the fuel pipe 26, the filter 28, and the inlet chamber 143 of the regulator 32, and the pressure will be locked in the line by the check valve at one end and the strongly closed regulator valve at the other end. The pressure will be line pressure and will be maintained by the force of the actuating spring '126 of the accumulator. This will yield to allow expansion of the liquid fuel if its temperature rises, but the pressure will maintain the fuel in liquid state even under extreme temperature rises. The outlet chamber 145 and the short pipe 36 to the carburetor valve 38 will also normally be full of liquid, but at a pressure within the range of the regulated outlet pressure from the regulator 32. The accumulator chamber 128 will contain a reserve supply of liquid under line pressure, and when the engine switch is turned on,- liquid fuel will be immediately available to the carburetor, from a point immediately adjacent the carburetor. and in a quantity sufiicient for initial operation of the engine. When the engine switch is turned on, this will also energize the pump motor 18 and the motor and pump will begin operation. Well before the reserve supply of fuel in the accumulator chamber 128 has been exhausted, the pump will have come to pumping speed at which its discharge pressure will be at or above the existing line pressure, and will supply fuel to the line to meet the engine demand and replenish the reserve-fuel supply in the accumulator chamber 128. During operation, the accumulator will exert regulating action on the line pressure, to maintain it if the pump output temporarily drops and to absorb shocks from any sur'ga in the pump output.

The fuel supplied by the pump to the fuel line and by the line to the fuel-mixing device will be substantially gas-free fuel. The fuel in the vented tank 10 will be at substantially atmospheric pressure and hence will contain no dissolved or absorbed gas by reason of any elevated pressure. This relatively gas-free fuel in the tank'will be subjected to a gas-separation action in the pump 16, by reason of centrifugal action in the swirling-inlet stream and the fact that the center portion of the inlet stream is by-passed back to the tank through the axial-flow impeller 78 and only the substantially gas-free fuel at the periphery of the stream is pumped by the radial-flow pump 72 into the fuel-supply system.

During pump operation, a small flow of fuel will be pumped through the passages to cool and lubricate the motor 18, and will be discharged through the pipe 92 at the top of the motor 18, to maintain the lower portion of the mounting sleeve 44 full of motor-cooling liquid up to the level of the openings 94, or to the level of fuel in the tank if it is higher.

The substantially gas-free fuel in the line will be transmitted to the regulator '32, and thus to a point close tc the fuel-mixing device of the engine, under the high line pressure of say 16 to 22 pounds per square inch Uuder these conditions, the fuel in the line will withstand temperature changes exceeding those which are likely to occur even under extreme conditions, withoul vaporizing in the line. The liquid fuel, containing nc vapor in gaseous form, will be discharged from the regulator, at a regulated pressure and under a regulated flow directly to the fuel-mixing device. While it is possible under extreme high-temperature conditions that gaseous vapor might form as the fuel pressure is decreased it the regulator, difficulties for this reason will be avoided by reason of the close spacing between the regulator 32 and the fuel-mixing device, and of the fact that an ample supply of fuel under line pressure is immediately available to purge the short connection 36 of gas and to supply liquid fuel to the carburetor-float chamber. Any possible fuel failure at this point will be so transitory in naturt that its effects will be dissipated before the fuel container in the carburetor will have been consumed, and no interruption of engine operation will occur.

Conditions strongly tending to produce vapor lock in automotive fuel systems occur when an engine which is hot from use is stopped. The cooling system is no longer efiective, the heat of the engine heats the entire engine-compartment to an excessive temperature, and the fuel is stagnant. Cooling from the excessive temperature eventually occurs, but for a considerable time the entire fuel system within the engine compartment is subjected to conditions which are conducive to vaporlock. With the fuel-supply system of this application, the entire fuel line up to a point close to the fuel-mixing device is under high pressure, which resists vaporization of fuel in that line. While vaporization from the carburetor can result in the escape of some liquid from the line to the carburetor under these conditions, the reserve quantity of liquid in the accumulator maintains the line full of liquid fuel under pressure during the period required for the excessive conditions to be dissipated.

Accordingly, if it is necessary to start the vehicle engine during these extreme conditions, liquid fuel is immediately available under pressure at a point close to the fuel-mixing device. As the engine is cranked, adequate amounts of liquid fuel will be delivered to the carburetor, any vaporization which occurs will cool the carburetor, the liquid fuel under pressure will promptly purge the carburetor of vapor, and the engine will start immediately. Reserve fuel from the accumulator will maintain operation until the pump reaches delivery pressure. The pump will then continue the required fuel flow and replenish the accumulator.

The accumulator thus has an important function in overcoming vapor-lock tendencies occurring under extreme conditions such as those described above; and where the vehicle may be called on for emergency use, I consider the accumulator an important part of the system. The accumulator also serves an important function in maintaining the operation of the vehicle when the fuel level in the tank is low, when movements of the vehicle may temporarily carry the fuel in the tank away from the inlet of the pump, and this factor is also of importance in vehicles subject to emergency or military service, especially when the vehicle may be operated over rough terrain.

Where the service requirements are less severe, however, a somewhat less expensive system may be used which contains no accumulator. For this purpose, the header shown in Fig. may be substituted for the header 20 of Fig. 2. It comprises a plate 220 conveniently adapted to fit the same mounting as the plate 20 in Fig. 2. It carries a depending collar 222 adapted to receive and support the upper end of the motor-mounting sleeve 44 and the upper ends of the tie rods 48. The plate 220 contains a bore 224 which receives the upper end of the pump-discharge pipe 76, and which provides a passage leading to an up-. wardly opening check valve 226. The valve 226 discharges to a connection elbow 230 on top of the plate 220, adapted for connection to the fuel line 26. The plate 220 also carries an insulated connector pin 232 by which the motor-lead wire 42 can be connected to the electrical system of the vehicle through the engine switch.

The omission of the accumulator may introduce a time delay in starting a hot engine, but the modified system nevertheless gives positive starting and avoids persistent vapor-lock troubles. In the extreme vapor-lock conditions occurring immediately after a hot vehicle is stopped, vaporization of fuel from the carburetor may cause the escape of such quantities of fuel from the fuel line that, in the absence of an accumulator, the pressure in that line may drop to a point which permits vaporization in that line itself. If an engine-starting operation is made when this condition exists, the initial closing of the engine switch will immediately start the pump. While it may take a short time for the pump to come up to full pumping capacity, it will soon do so, and its high capacity and high discharge pressure will soon charge the line to full pressure. The line and the carburetor will be purged of any vapor therein, and the carburetor will then receive liquid fuel. This result will occur whether or not the engine is being cranked, since the submerged pump operates at full capacity independently of rotation of the engine. With liquid fuel at the carburetor, subsequent cranking rotation of the engine will result in a positive engine start, and running operation will be maintained by the fully operating pump. The modified fuel system may not permit the engine to be started as immediately as occurs when the accumulator is present, but positive starting will occur after not more than a short wait while the pump comes up to full capacity and purges the system of vapor.

The fuel system not only gives advantageous results with a carburetor engine, as discussed above, but also with fuel-injectior engines which require high-pressure fuel supply, and is of further advantage in that the two types of engines may be interchanged freely in a vehicle equipped with the fuel supply system.

For such interchange, the fuel system is connected to the fuel injector in the same way as to the carburetor. The line pressure of the system is suitable as the inlet pressure to high-pressure fuel injectors, and the fuel-regulator is therefore locked open by means of the plunger 157. The pressure is then controlled by the injector itself rather than by the regulator, and the pump maintains the pressure at whatever flow rates the injector demands.

In this arrangement, the system supplies vapor-free liquid fuel, which is even more essential to proper operation of injectors than it is to carburetors which can eflect some vapor separation in their float bowls.

I claim as my invention:

In combination with a vehicle having an engine compartment and a remotely disposed fuel tank, a fuel system therefor comprising a centrifugal pump mounted in submerged position in the fuel tank and adapted to pump fuel therefrom at a high rate and pressure, a check valve at the tank in the discharge line from the pump, a fuel line leading from said check-valve to the engine compartment, an accumulator mounted with the pump and communicating with said fuel line downstream from the check valve, to maintain at a high line pressure the fuel contained in the accumulator and the fuel line, a pressure-regulator in the engine compartment at the outlet end of said fuel line, said regulator being operative to deliver liquid fuel at a use-pressure substantially below line pressure.

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