DE3514196A1 - FUEL SUPPLY SYSTEM FOR INTERNAL COMBUSTION ENGINES WITH FUEL INJECTION - Google Patents

Description

Patent application P FORD / US-1401/16. April 1985

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Fuel supply system for internal combustion engines with fuel injection

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The invention relates to a fuel supply system for Internal combustion engines with fuel injection of the type explained in the preamble of claim 1.

In internal combustion engines that are supplied with fuel by a carburetor the conventional float chamber forms a certain reservoir that maintains the undisturbed operation of the internal combustion engine, even if the supply of fuel from the fuel tank is briefly interrupted, which occurs when the mostly in the

Fuel pump arranged in the fuel tank for strong longitudinal or 15

Slope of the motor vehicle sucks in air.

Internal combustion engines supplied with fuel by an injection system normally do not have such a reservoir

however, as a rule, two fuel pumps, one of which is low pressure 20

pump the fuel out of the fuel tank via a supply line Suction side of a high pressure pump leads, which supplies the actual injection system with fuel. This high pressure pump promotes this always a larger amount of fuel than required by the injection system

is, so that a pressure 25

reduction a return line to the fuel tank can be provided got to.

In a conventional fuel supply system for an internal combustion engine with fuel injection it can therefore be at intermittent 30

Interruption of the fuel supply supplied by the low pressure pump to disturbances in the operation of the internal combustion engine.

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\ BAD ORIGINAL

Patent application P "-iÜRD / US-1401 / April 16, 1985

From US-PS 4,320,734 a fuel supply system for a Diesel internal combustion engine known, in which a reservoir is provided in the return line for the excess fuel, which has a Throttle point is connected to the supply line to the suction side of the high pressure pump. This throttle point is always open and only allows a small amount of fuel the inflow to the feed line to the high pressure pump and can therefore only short-term disturbances of the fuel supply equalize from the low pressure pump.

The object of the invention is to provide a fuel supply system for Internal combustion engines with fuel injection of the type explained in the preamble of claim 1 to improve such that with undisturbed Fuel supply the excess fuel is fed directly to the fuel tank via the return line while

the return line is switched over in this way in the event of faults in the fuel supply 15th

will that all the excess amount of fuel in the reservoir is performed and is available to compensate for the disturbance in the fuel supply.

According to the invention, this object is achieved by in a fuel supply system for internal combustion engines with fuel injection of the type explained in the preamble of claim 1, the measures indicated in the characterizing part of claim 1 are provided will.

Expedient embodiments of the invention are explained in claims 2 to 4.

In that two arms are provided in the return line, one of which

one lead to the fuel tank and the other to the reservoir and 30th

Check valves are arranged in the arms, which at low fuel pressure in the direction of the fuel tank and in the direction of the reservoir open and close in the opposite direction if the fuel supply is undisturbed the excess fuel directly to the fuel tank M If there is a malfunction in the fuel supply, the excess would be retained Amount of fuel is diverted into the reservoir.

Because the check valves are designed in the form of spring-loaded disk or diaphragm valves or simple lip valves are, the structural effort is very low.

The fact that the reservoir and the check valves in the housing of a Uu

Fuel filter are integrated, with the check valves in the upper housing are arranged, while the lower cup-shaped, an annular filter cartridge receiving housing forms the reservoir, it is also possible to compensate for longer-lasting disturbances in the fuel supply.

Because a bore leads to the return line via a throttle point, air can escape from the reservoir when it is refilled.

The invention is shown with reference to FIG. 15 in the accompanying drawings

th embodiments explained in more detail.

It shows:

Figures 1 and 2
^B.

a schematic representation of a fuel supply system according to the invention in the normal position or in Fault situation;

Fig. 3 is a plan view of a further embodiment of a

Fuel supply system according to the invention and

FIG. 4 shows a vertical section along the line IV-IV in FIG

Fig. 3.

In Figures 1 and 2, a reservoir 10 is in the form of a cylindrical Indicated container in which the fuel is normally on a level indicated in dashed lines 12. The reservoir 10 is in this case supplied with fuel via a feed line 14, which is in connection with a low-pressure pump, which is usually in the fuel tank (not shown) is arranged. This low pressure pump normally delivers fuel at a pressure between 0.21 and 0.35 bar.

Patent application P "'" TORD / US-1401/16. April 1985

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The reservoir 10 has a feed line 16 to the suction side of a high pressure pump (not shown) connected, the end of which extends to the bottom of the reservoir 10. The high-pressure pump delivers fuel for example with a pressure of 2.73 bar to one or more of the injection nozzles.

The reservoir 10 is connected to an arm 18 which extends from the return line 20 goes out for the excess amount of fuel, one arm 22 of which is connected to the pressure reducing valve of the high pressure pump and the other arm 24 of which leads to the fuel tank.

The two arms 18 and 24 of the return line 20 are according to the invention provided with check valves 28 and 26, which are designed as simple disc valves 31 and 30, which by springs 32 with less Force are applied so that the check valves are already at

open low fuel pressures of 0.035 bar. 15th

During operation of the fuel supply system, the Feed line to the suction side of the high pressure pump, a suction pressure of 0.14 bar occurs. The fuel supply from the low pressure pump via the feed line 14 takes place with a fuel pressure of 0.21 to 0.35 bar,

so that even after subtracting the suction pressure of 0.14 bar from the high pressure pump a fuel pressure is maintained in the reservoir 10, which presses the disc valve 31 into its closed position, since the fuel pressure in the return line 20 is reduced to about 0.07 to 0.105 bar. This

On the other hand, pressure is sufficient to ent-25 the disk valve 30 in the arm 24

open against the force of the spring 32, so that the excess amount of fuel can flow directly into the fuel tank.

The motor vehicle takes extreme things when driving off-road, for example Transverse or longitudinal inclinations, which is indicated in FIG. 2 by the oblique representation of the fuel supply system, can be a Disturbance in the fuel supply in the feed line 14 occur in that the low-pressure pump sucks in air in the fuel tank. Through this atmospheric pressure reaches the reservoir 10 and via the supply line 14

As a result, the fuel pressure in the reservoir 10 will drop so far that 35

Patent application P FORD / US-1401/16. April 1985

the fuel pressure in the return line 20 from 0.07 to 0.105 bar in Is able to open the disc valve 31 against the force of the spring 32, whereby the excess amount of fuel directly into the Reservoir 10 is performed.

In Figures 3 and 4 is a further embodiment of a fuel supply system shown according to the invention. The reservoir according to the invention and the check valves are in this case in two parts Housing 36 and 38 of a fuel filter 34 are integrated.

The fuel filter 34 consists of an upper base or housing part 38, with which a lower, cup-shaped housing part 36 by screwing can be connected. The cup-shaped housing part 36 here takes a filter cartridge 40 in the form of an annular folded one Paper filter with upper and lower annular disks 42 and 44, the interior of which has a central bore 46 with the interposition of an annular seal 50 is connected to channels 52 and 54, which supply a supply line 56 to the high pressure pump. In the upper base or housing part 38 two valve bores 58 and 60 are also provided. The one valve hole 58 is at its lower end in connection with the interior of the cup-shaped housing part 36 and is connected to a check valve 28 provided, which enables an inflow in the direction of the reservoir, but prevents it in the opposite direction. The top of the valve bore 58 is in communication with a part of the return line 20 via a channel and has a check valve 26 which extends in the direction of the fuel tank opens, but closes in the opposite direction. Both check valves 26 and 28 open at a low fuel pressure of 0.035 bar.

An additional check valve 64 is located in the other valve bore 60 30th

arranged, which allows an inflow towards the reservoir 36, in However, the opposite direction is prevented. The check valve 64 again consists of a movable disc 66, which under spring pressure 68 against a annular valve seat 70 is pressed. Acts fuel pressure on the

Washer 66, it can yield against the force of the spring 68 35

Patent application P FORD / US-1401/16. April 1985

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and fuel can enter the reservoir through openings 72 in the valve housing 36 arrive. The valve bore 64 is connected via a channel 76 to the feed line 14, which carries fuel from the low-pressure pump leads.

A bore 80 also runs in the upper base or housing part 38 with a throttle opening 82 which opens into the return line 20 and which enables the reservoir 36 to be vented. The fuel filter 34 can be attached to the motor vehicle via attachment devices 84 and 86.

The function of the fuel supply system according to Figures 3 and 4 is essentially the same as that explained in connection with FIGS. 1 and 2.

If the function is normal, the low-pressure pump delivers fuel with a pressure of 0.21 to 0.35 bar and thereby opens the check valve 64 and fills the filter cartridge 40 located on the outside Space 88 of the fuel filter 34 with fuel. The fuel flows through the filter material of the filter cartridge 40 and passes over the Opening 46 and the channels 52 and 54 to the supply line 16 to the high pressure pump. The excess fuel comes from the high pressure pump Pressure reduction via the arm 22 of the return line 20 via the channel 90 into the upper housing 38 of the fuel filter 34 and opens with it its pressure of 0.07 to 0.105 bar, the check valve 26 and passes through the arm 24 of the return line 20 to the fuel tank. The im Inside the reservoir 36 effective pressure of 0.21 to 0.35 bar keeps the check valve 28 closed and prevents an inflow from return line 20 to reservoir 36.

If the motor vehicle assumes a driving state in which there is such a Longitudinal or transverse inclination experiences that the suction line of the low-pressure pump sucks in air in the fuel tank, so the pressure in the falls Feed line 14 and in the channel 76 and prevent sucking back

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Check valve 64 closes. Now the Suugdruek of otwn has an effect 0.07 to 0.14 bar of the high pressure pump in the interior of the reservoir 36 and thereby opens the check valve 28 and enables a Inflow of fuel from the return line 20 into the reservoir 36.

Since the fuel inflow via the return line 20 is less than the requirements of the internal combustion engine, the fuel level in the reservoir 36 will fall. The filter cartridge 40 acts like a suction lifter, ie initially the fuel level in the outside area drops, whereas the fuel level inside the filter cartridge 40 initially remains as a full column and ensures an uninterrupted supply of the high-pressure pump. The surface tension of the fuel in the filter material seals the open space from the interior and prevents the inner fuel column from collapsing. The reservoir 36 is designed in such a way that

that in this state there is a need for the internal combustion engine for a few minutes can take over. Only then does the inner fuel column collapse and the reservoir 36 becomes air via the bore 80 and 82 suck in if the delivery of the low-pressure pump has not started again beforehand.

In this way, the invention creates a fuel supply system, which allows for several minutes to compensate for malfunctions in the fuel supply caused by location conditions of the motor vehicle, causing the engine to die in most of the 25th

Cases are avoided because the low pressure pump recommences delivery refills the reservoir.

BATH ORIGINAL

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Claims (4)

Patent application P -. ■ "..-: FÖRD / US-1401 / April 16, 1985 Claims Fuel supply system for internal combustion engines with fuel injection, in which a low-pressure pump _{feeds fuel from an O} g container via a feed line into a reservoir, one of which Supply fuel to the suction side of a high-pressure pump performs, on the pressure side via a pressure reducing valve, excess fuel via a return line at low pressure to the container and is guided to the reservoir, characterized in that in the rear _ft line (20) has two arms (24 and 18) provided are of which the one (24) leads to the container and the other (18) leads to the reservoir (10) and in the arms (24 and 18) check valves (26 and 28) are arranged, which in the case of low fuel pressure in the direction of the container or open towards the reservoir (10) and close in the opposite direction. 2. Fuel supply system according to claim 1, characterized in that that the check valves (26 and 28) in the form of a spring (32) loaded disc or diaphragm valves (30 and 31) or designed as lip valves. 3. Fuel supply system according to claims 1 and 2, characterized characterized in that the reservoir and the check valves are integrated in the housing (36 and 38) of a fuel filter (34), the check valves (26 and 28) being arranged in the upper housing (38) are, while the lower, cup-shaped, an annular filter pa-25 Trone (40) receiving housing (36) forms the reservoir. 4. Fuel supply system according to claim 3, characterized in that a bore (80) with a throttle point (82) for ventilation of the Reservoir (36) is connected to the return line (20). 30th