JP2844949B2 - Fuel supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply device provided with a jet pump.

[0002]

2. Description of the Related Art Conventionally, a fuel supply device equipped with a jet pump is mounted on transportation equipment (automobiles, ships, etc.).
As an example of this fuel supply device, FIG. 4 shows a fuel supply device for a vehicle-mounted diesel engine. 4, the fuel tank 31 has a first bottom 32 and a second bottom 33, and a sub-tank 34 having a small hole is arranged in the first bottom 32, and the fuel in the sub-tank 34 is supplied by a fuel injection pump. Through the inlet pipe 35, a part of the fuel is sucked and supplied to the engine, and the rest of the sucked fuel is supplied to the overflow pipe 36. Further, the fuel in the overflow pipe 36 is returned to the sub-tank 34 of the fuel tank 31 via the jet nozzle 38 of the jet pump 37, and the fuel in the second bottom 33 is transferred to the sub-tank 34 by the negative pressure downstream of the jet nozzle 38. Then, the sub tank 34 is filled with fuel. The sub tank 34 surrounds the fuel outlet of the jet pump 37 and the inlet pipe 35 in close proximity so that air is not sucked from the inlet pipe 35 when the vehicle turns or leans.

[0003]

However, the second bottom 33
When the fuel is exhausted, there is nothing to suck up and the air is sucked. The air mixes with the overflow fuel, and the jet pump 37 injects the gas-liquid mixed fuel.
In the apparatus shown in FIG. 4, the fuel outlet of the jet pump 37 and the opening of the inlet pipe 35 are close to each other in the sub-tank 34, and when the fuel in the second bottom 33 is empty, the jet of the jet pump 37 Thus, there is a problem that the gas-liquid mixed fuel is sucked from the inlet pipe 35, and the function of the fuel injection pump is hindered.

It is an object of the present invention to provide a fuel supply apparatus which does not adversely affect a fuel pump even when a gas-liquid mixed fuel is injected by a jet pump.

[0005]

The present invention has a first bottom portion and a second bottom portion which are distributed, and when the amount of fuel remaining inside becomes small, the first bottom portion and the second bottom portion are separated from each other. And a fuel tank having a structure in which fuel remains in each of the fuel tanks. The fuel at the first bottom of the fuel tank is sucked up through a suction pipe, a part of the fuel is supplied to the engine, and the rest of the sucked fuel is fed through a fuel return pipe. A fuel pump for returning fuel to the fuel tank, and returning fuel from the fuel return pipe to a first bottom of the fuel tank via a jet nozzle, and a fuel at a second bottom of the fuel tank due to a negative pressure downstream of the jet nozzle. And a jet pump for transferring the fuel to the first bottom portion, wherein a sub-tank is arranged at the first bottom portion of the fuel tank and the sub-tank is disposed in the sub-tank. A communication hole communicating with the outside was formed, and the end of the suction pipe of the fuel pump was arranged in the sub tank, and the end of the relief pipe branched from the upstream side of the jet nozzle of the jet pump was arranged in the sub tank. The gist is a fuel supply device.

Preferably, the relief pipe is provided with a relief valve.

[0007]

When the fuel pump is driven, fuel in the sub tank at the first bottom of the fuel tank is sucked up through the suction pipe, a part of the fuel is supplied to the engine, and the rest of the sucked fuel is supplied to the fuel return pipe. You. Then, in the jet pump, the fuel in the fuel return pipe is returned to the outside of the sub tank at the first bottom of the fuel tank via the jet nozzle, and the fuel at the second bottom of the fuel tank is discharged by the negative pressure on the downstream side of the jet nozzle. Transferred out of the sub-tank at the first bottom. Further, fuel on the upstream side of the jet nozzle of the jet pump is supplied into the sub-tank through the relief pipe. Then, when fuel is exhausted at the second bottom of the fuel tank, air is supplied from the second bottom of the fuel tank to the downstream side of the jet nozzle, and the gas-liquid mixed fuel is transferred to the outside of the sub tank at the first bottom. However, this gas-liquid mixed fuel only exists outside the sub-tank at the first bottom, and is not sucked up through the suction pipe by the fuel pump.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the overall configuration of a fuel supply device for a diesel engine, and this fuel supply device is mounted on an automobile. The fuel tank 1 has a first bottom 2 and a second bottom 3 so that when the amount of fuel (light oil) remaining inside becomes small, the fuel remains in each of the first bottom 2 and the second bottom 3. It has become. A sub-tank 4 is disposed at the first bottom 2 of the fuel tank 1, and the capacity of the sub-tank 4 is much smaller than the capacity of the first bottom 2 outside the sub-tank 4. At the bottom of sub-tank 4, sub-tank 4
A communication hole (small hole) 5 communicating the inside and the outside of the hole is formed.

The distribution type fuel injection pump 6 is of a Bosch type and is driven by the application of rotational force from a diesel engine E. An inlet pipe 7 serving as a suction pipe is connected to the fuel injection pump 6, and the pipe 7 extends to the bottom of the sub tank 4 of the fuel tank 1. Then, the fuel in the sub tank 4 of the fuel tank 1 is sucked up by driving the fuel injection pump 6, and a part of the fuel is supplied to the fuel injection nozzle 8 of the diesel engine E. An overflow pipe 9 as a fuel return pipe is connected to the fuel injection pump 6, and the remainder of the fuel sucked up through the inlet pipe 7 is discharged to the overflow pipe 9.

The overflow pipe 9 extends to the inside of the fuel tank 1, and a jet pump 10 is provided at the tip thereof. This jet pump 10 is shown in FIG.
In FIG. 2, a jet nozzle 1 is provided in a housing 11.
2 and a venturi 13 are formed, and the fuel in the overflow pipe 9 is supplied to the jet nozzle 12 and the venturi 1 disposed downstream of the jet nozzle 12
Fuel is discharged through 3. This fuel outlet is shown in FIG.
As shown in the figure, the first bottom portion 2 of the fuel tank 1 is outside the sub tank 4 and on the opposite side of the communication hole 5 of the sub tank 4. A suction passage 14 is formed downstream of the jet nozzle 12, and a suction pipe 15 is connected to the suction passage 14 as shown in FIG.
This suction pipe 15 is connected to the second bottom 3 of the fuel tank 1.
Has been extended. Then, the fuel in the second bottom portion 3 of the fuel tank 1 is sucked by the negative pressure on the downstream side of the jet nozzle 12.

Further, a relief pipe 17 is provided on the upstream side of the jet nozzle 12 of the jet pump 10 via a relief valve 16.
Extends to a position near the inlet pipe 7 in the sub tank 4. That is, the valve chamber 19 of the relief valve 16 is formed in the housing 11, and the valve chamber 19 communicates with the upstream passage of the jet nozzle 12 via the passage 18. A valve body 20 that opens and closes the passage 18 is disposed in the valve chamber 19, and the valve body 20 is urged by a spring 21 in a direction to close the passage 18. The fuel pressure on the upstream side of the jet nozzle 12 is
When the set load is exceeded, the passage 18 is opened, and the relieved fuel is supplied into the sub-tank 4 via the relief pipe 17.

Next, the operation of the fuel supply device configured as described above will be described. The fuel in the sub tank 4 is sucked up through the inlet pipe 7 by the driving of the fuel injection pump 6 accompanying the rotation of the diesel engine E, a part of the fuel is supplied to the fuel injection nozzle 8, and the remaining fuel is sucked up by the overflow pipe 9. Supplied to The fuel in the overflow pipe 9 is introduced into the jet pump 10 and generates a negative pressure to suck up the fuel in the second bottom 3 through the suction pipe 15 and supply it to the outside of the sub-tank 4 in the first bottom 2. When the fuel in the overflow pipe 9 becomes higher than the pressure set by the relief valve 14 of the jet pump 10, the fuel is supplied into the sub tank 4 through the relief pipe 17.

When the fuel in the second bottom 3 becomes empty, air is sucked into the suction pipe 15. As a result, in the jet pump 10, the fuel that has overflowed and the air that has been sucked in through the suction pipe 15 are mixed and become gas-liquid mixed fuel, which is discharged out of the sub tank 4 of the first bottom 2. At this time, jet pump 1
Since 0 is located on the side opposite to the communication hole 5 of the sub-tank 4, bubbles injected by the jet pump 10 are not sent into the sub-tank 4. That is, the bubbles reach the oil level while flowing around. Therefore, there is no possibility that air bubbles are sucked from the inlet pipe 7 and adversely affect the function and reliability of the fuel injection pump 6. In other words, in the fuel injection pump 6, it is possible to prevent the fuel for lubricating the operating portion from containing air bubbles and causing seizure, and prevent the air bubbles from changing the pump characteristics (delaying the advance angle characteristics of the timer). You.

Further, since the sub-tank 4 has the communication hole 5, the liquid level in the sub-tank 4 at the first bottom 2 and the liquid level outside the sub-tank 4 are kept at the same level during normal running and stopping. In addition, when the vehicle is leaning or turning, the fuel moves to one side, so that the fuel cannot be sucked from the inlet pipe 7 and the engine stalls. Furthermore, the volume inside the sub tank 4 is sufficiently smaller than the volume outside the sub tank 4 at the first bottom 2, and
Since the inside and outside of the sub-tank 4 communicate with each other through the sufficiently small communication hole 5, even if the fuel outside the sub-tank 4 at the first bottom 2 is biased during turning or the like, the liquid level of the fuel in the sub-tank 4 is higher than a predetermined height. The tip of the inlet pipe 7 is kept in the liquid.

In addition, even when the fuel in the sub-tank 4 flows out of the sub-tank 4 at the first bottom 2 when the fuel is biased for a long time such as when traveling on an inclined surface, the inlet pipe 7 and the relief pipe 17 are arranged close to each other. As a result, the overflow fuel can be immediately sucked through the inlet pipe 7, thereby avoiding adverse effects on the function and reliability of the fuel injection pump 6.

In this embodiment, the overflow pipe 9
The return flow rate is reduced as compared with the case where all the overflow fuel is returned into the sub-tank 4, but as shown in FIG. 3, the nozzle injection flow rate is almost constant regardless of the engine speed. The fuel pressure on the upstream side of 12 increases and the relief flow rate increases. Therefore, ΔQ (= −) in FIG.
If the fuel supply from the outside of the sub-tank 4 through the communication hole 5 to the inside of the sub-tank 4 is lost under some conditions such as the inclination of the vehicle, the sub-tank 4
The fuel inside will decrease. However, since the communication hole 5 is opened at the bottom of the sub tank 4, there is no problem in a state where the fuel is sufficiently present in the tank. The shortage becomes a problem when the remaining fuel amount becomes small, but the shortage ΔQ is a little short in the entire rotation range, and the vehicle tilts when the communication hole 5 is above the liquid level. Is rarely continued for a long time, so that the fuel in the sub tank 4 does not run out at all.

As described above, in the present embodiment, the sub-tank 4 is disposed at the first bottom 2 of the fuel tank 1 and the communication hole 5 for communicating the inside and the outside of the sub-tank 4 is formed at the bottom of the sub-tank 4. The end of the inlet pipe 7 (suction pipe) of the pump 6 was arranged, and the end of the relief pipe 17 branched from the upstream side of the jet nozzle 12 of the jet pump 10 in the sub tank 4 was arranged. Therefore, when fuel is exhausted from the second bottom 3 of the fuel tank 1, air is supplied from the second bottom 3 of the fuel tank 1 to the downstream side of the jet nozzle 12, and the gas-liquid mixed fuel is supplied to the sub-tank at the first bottom 2. 4
This gas-liquid mixed fuel only exists outside the sub tank 4 at the first bottom 2, and is not sucked up by the fuel injection pump 6. Thus, the jet pump 10
Accordingly, even if the gas-liquid mixed fuel is injected, the fuel injection pump 6 is not adversely affected.

The present invention is not limited to the above-described embodiment. For example, in the above-described embodiment, the tank 1 is formed as a saddle type and integrally formed, but the first bottom 2 and the second bottom 3 are separately formed. May be formed of a tank and connected by a pipe or the like. Further, in the above embodiment, the communication hole 5 is formed at the lowermost part of the sub tank 4, but the position of the communication hole 5 may be changed as needed.

[0019]

As described above in detail, according to the present invention, an excellent effect is obtained which does not adversely affect the fuel pump even when the gas-liquid mixed fuel is injected by the jet pump.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a fuel supply device according to an embodiment.

FIG. 2 is a sectional view of a jet pump.

FIG. 3 is a diagram illustrating a relationship between an engine speed and a flow rate.

FIG. 4 is a diagram for explaining a conventional fuel supply device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel tank 2 1st bottom 3 2nd bottom 4 Subtank 5 Communication hole 6 Fuel injection pump 7 Inlet pipe as a suction pipe 9 Overflow pipe as a fuel return pipe 10 Jet pump 12 Jet nozzle 17 Relief pipe E Diesel engine

Claims (2)

(57) [Claims] A first bottom portion and a second bottom portion which are distributed, and wherein the first bottom portion is provided when a small amount of fuel remains therein.
A fuel tank having a structure in which fuel remains at each of a bottom portion and the second bottom portion, and a portion of the fuel at the first bottom portion of the fuel tank which is sucked up through a suction pipe and supplied to the engine, and a remaining portion of the sucked fuel is provided. A fuel pump for returning to the fuel tank via a fuel return pipe;
A jet for returning fuel from the fuel return pipe to the first bottom of the fuel tank via a jet nozzle and transferring fuel at a second bottom of the fuel tank to the first bottom by negative pressure downstream of the jet nozzle. In a fuel supply device provided with a pump, a sub-tank is arranged at a first bottom of the fuel tank, a communication hole communicating between the inside and outside of the sub-tank is formed, and an end of a suction pipe of the fuel pump is arranged in the sub-tank. A fuel supply device, wherein an end of a relief pipe branched from an upstream side of a jet nozzle of the jet pump is arranged in a sub tank. 2. The fuel supply device according to claim 1, wherein the relief pipe is provided with a relief valve.