JPH11201100A - Jet pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To securely carry fuel in an auxiliary camber by constantly keeping the inside of a negative pressure chamber at a negative pressure. SOLUTION: In a jet pump 11 provided with a negative pressure chamber 13 disposed to surround a nozzle 12 to jet return fuel 9 into a main chamber 1 of a fuel tank and faced with the underside of the main chamber 1 at a tip part 14 inside which negative pressure is formed when return fuel 9 is jetted the nozzle 12 to carry fuel in an auxiliary chamber 2 to the main chamber 1 by negative pressure in the negative pressure chamber 13 through a communication passage 15, a mesh member 16 is provided at a lower end of the tip part 14 of the negative pressure chamber 13, so an oil film 18 is formed by blown fuel on the mesh member 16 where return fuel 9 will not flow, thereby inflow of air into the negative pressure chamber 13 is prevented by the oil film 18 to constantly keep the inside of the negative pressure chamber 13 at a negative pressure regardless of a liquid level of fuel for securely carrying fuel in the auxiliary chamber 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a jet pump for feeding fuel in a sub chamber to a main chamber in a fuel tank partitioned into a main chamber and a sub chamber.

[0002]

2. Description of the Related Art In a four-wheel drive vehicle, an FR vehicle, and the like, a propeller shaft and the like are disposed on the lower surface of the vehicle. Therefore, as shown in FIG. A so-called saddle type fuel tank 3 is employed (for example, Utility Model Registration Publication No. 2500901). The main chamber 1 of the fuel tank 3 is provided with a main pump 4 for pumping fuel to the engine side.
The fuel inside is supplied to the main chamber 1 by a jet pump 5 driven by the main pump 4.

A conventional jet pump 5 will be described with reference to FIG. FIG. 5 shows a schematic configuration of a conventional jet pump. As shown in the figure, a nozzle 6 for ejecting return fuel 9 from the engine side into the main chamber 1 is provided, and the periphery of the nozzle 6 is covered with a negative pressure chamber 7. The tip 8 of the negative pressure chamber 7 faces below the main chamber 1, and when the return fuel 9 is ejected from the nozzle 6 into the main chamber 1 at high speed through the inside of the tip 8, the inside of the negative pressure chamber 7 becomes negative. Pressured. The upper part of the negative pressure chamber 7 is connected to the sub chamber 2 by a communication pipe 10.

When the return fuel 9 is ejected from the nozzle 6 to the main chamber 1 through the inside of the distal end portion 8, the inside of the negative pressure chamber 7 is made negative. When the inside of the negative pressure chamber 7 becomes a negative pressure, the fuel in the sub chamber 2 is sucked into the negative pressure chamber 7 through the communication pipe 10 and sent into the main chamber 1 together with the return fuel 9. As described above, the fuel in the sub chamber 2 is transferred to the main chamber 1 by utilizing the negative pressure generated in the negative pressure chamber 7 by returning the return fuel 9 from the nozzle 6 at a high speed.

[0005]

In the above-described jet pump 5, the return fuel 9 blown out from the nozzle 6 is thinner than the inner diameter of the tip portion 8, and a gap is formed around the tip. For this reason, when the liquid level in the main chamber 1 becomes lower than the lower end of the distal end portion 8 as in the state from the state in the figure, air flows in between the return fuel 9 and the distal end portion 8,
In some cases, the negative pressure in the negative pressure chamber 7 becomes insufficient and the fuel in the sub chamber 2 cannot be transferred.

[0006] In the saddle type fuel tank 3, both the main chamber 1 and the sub chamber 2 are provided with level gauges.
When the fuel inside the chamber cannot be transferred, the fuel in the main chamber 1 runs out despite the fuel gauge indicating a sufficient remaining amount, and the fuel cannot be transferred to the engine side by the main pump 4.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a jet pump which can always maintain negative pressure in a negative pressure chamber and reliably transfer fuel in a sub-chamber. .

[0008]

In order to achieve the above object, according to the present invention, the return fuel is disposed so as to cover the periphery of a nozzle for jetting the return fuel into the main chamber of the fuel tank, and the tip of the return fuel faces downwardly of the main chamber. A negative pressure chamber in which a negative pressure is generated when the fuel is ejected from the nozzle, and a fuel passage in the sub-chamber is transferred to the main chamber by the negative pressure in the negative pressure chamber through the communication path. An air inflow prevention means is provided on the side, and the inflow of air into the negative pressure chamber is prevented by the air inflow prevention means, and the negative pressure chamber is always maintained at a negative pressure to reliably transfer the fuel in the sub chamber.

As the air inflow prevention means, a resin mesh member provided at the opening at the tip is applied, and an oil film is formed by the return fuel on the mesh member other than where the return fuel flows, and the air film is formed by the oil film. Prevent inflow. In addition, as the air inflow prevention means, a thin rod attached to the middle of the tip is used, and the return fuel is diffused by the rod to eliminate a gap between the inside of the tip and prevent air from flowing. I do.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a jet pump according to an embodiment of the present invention. The jet pump in the illustrated example is provided in the fuel tank 3 shown in FIG. 4 and transfers fuel from the sub chamber 2 to the main chamber 1. Therefore, the same members as those shown in FIG. Reference numerals are given and overlapping description is omitted.

As shown in FIG. 1, a jet pump 11 is provided with a nozzle 12 for injecting return fuel 9 from the engine side into the main chamber 1. Around the nozzle 12 is a negative pressure chamber 13.
Covered with. The negative pressure chamber 13 has a cylindrical distal end 14 extending downward, and the lower end of the distal end 14 faces below the main chamber 1. When the return fuel 9 is ejected from the nozzle 12 at high speed into the main chamber 1 through the inside of the distal end portion 14, the negative pressure chamber 1
The inside of 3 is made negative pressure. The upper part of the negative pressure chamber 13 is the communication pipe 1
5 connects to the sub-chamber 2.

At the opening at the lower end of the cylindrical tip 14, there is provided a disk-shaped mesh member 16 made of, for example, resin (air inflow prevention means). The mesh member 16 is fastened by a fastening band 17 to the lower end of the tip 14. The outer circumference is fixed to. The mesh member 16 may be fixed to the distal end portion 14 directly by welding or the like.

The mesh member 16 is the same as the mesh member provided at the suction port of the fuel pump for preventing foreign matter from being sucked, and the return fuel 9 ejected from the nozzle 12 can flow to the main chamber 1 without resistance. In addition, the fuel film 18 has a roughness such that the oil film 18 is formed by the fuel blown out to the portion of the gap between the return fuel 9 and the tip portion 14.

If the oil film 18 is formed in such a manner that the oil film 18 can be formed in the gap between the return fuel 9 and the tip 14, the nozzle 1
In some cases, the opening area for circulation of the return fuel 9 ejected from the nozzle 2 is insufficient, causing flow path resistance to cause a decrease in flow rate. In this case, as shown in FIG. 2, a bag-shaped mesh member 21 is fixed to the opening at the lower end of the tip portion 14, and a sufficient opening area is secured to prevent a decrease in flow rate.

By driving a main pump (not shown), the return fuel 9 is spouted from the nozzle 12 into the main chamber 1 at a high speed through the inside of the cylindrical tip portion 14, so that the interior of the negative pressure chamber 13 is made negative. You. Return fuel 9 is mesh member 1
6, an oil film 18 is formed on the mesh member 16 at a portion of the gap with the tip portion 14 by the blown fuel.

When the pressure inside the negative pressure chamber 13 becomes negative, the sub-chamber 2
The fuel in the sub-chamber 2 is sucked into the negative pressure chamber 13 through the communication pipe 15, and the fuel in the sub-chamber 2 merges with the return fuel 9 to form the main chamber 1.
Sent inside. As described above, the fuel in the sub chamber 2 is transferred to the main chamber 1 by utilizing the negative pressure generated in the negative pressure chamber 13 by the return fuel 9 blowing out from the nozzle 12 at a high speed. At this time, when the fuel in the sub-chamber 2 and the return fuel 9 merge, the flow velocity becomes slow, and the flow rate does not decrease when flowing through the mesh member 16.

In the above-described jet pump 11, the return fuel 9 blown out from the nozzle 12 is thinner than the inner diameter of the tip portion 14, and a gap is formed in the periphery. Since the oil film 18 is formed by the blown fuel on the mesh member 16 at the portion of the gap, the liquid level in the main chamber 1 is lower than the lower end of the tip portion 14 as in the state from the state in the figure. Even in the state, the inflow of air is blocked by the oil film 18. For this reason, even if the liquid level in the main chamber 1 becomes low, air does not flow into the negative pressure chamber 13, the inside of the negative pressure chamber 13 is always maintained at a negative pressure, and the transfer of fuel in the sub chamber 2 is performed. Can be performed reliably.

Next, a second embodiment will be described with reference to FIG. FIG. 3 shows a schematic configuration of a jet pump according to a second embodiment of the present invention. The same members as those of the jet pump shown in FIG. 1 are denoted by the same reference numerals, and duplicate description is omitted.

As shown in the drawing, a rod 32 (about 1.0 mm to 2.0 mm in diameter) as an air inflow preventing means penetrates the jet pump 31 in the vicinity of an intermediate portion of the cylindrical tip portion 14. Have been. When the return fuel 9 is ejected from the nozzle 12 at high speed through the inside of the cylindrical distal end portion 14 into the main chamber 1, the return fuel 9 is diffused by the rod material 32 and a gap is formed between the return fuel 9 and the inner surface of the distal end portion 14. Will not occur.

The return fuel 9 is jetted from the nozzle 12 at high speed through the inside of the cylindrical tip portion 14 to the main chamber 1,
A negative pressure is generated in the negative pressure chamber 13 and the fuel in the sub chamber 2 is transferred to the main chamber 1. The return fuel 9 is moved to the tip 1 by the rod 32.
4, even if the liquid level in the main chamber 1 becomes lower than the lower end of the distal end portion 14 as in the state from the state in the figure, the diffused return fuel 9 causes air to be diffused. Inflow is blocked. For this reason, even if the liquid level in the main chamber 1 becomes low, air does not flow into the negative pressure chamber 13, the inside of the negative pressure chamber 13 is always maintained at a negative pressure, and the transfer of fuel in the sub chamber 2 is performed. Can be performed reliably.

[0021]

According to the jet pump of the present invention, the air inflow preventing means is provided on the tip side of the negative pressure chamber, so that the air can be prevented from flowing into the negative pressure chamber by the air inflow preventing means. As a result, regardless of the state of the liquid level in the fuel tank, it is possible to always maintain the negative pressure in the negative pressure chamber and transfer the fuel in the sub-chamber reliably.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a jet pump according to an embodiment of the present invention.

FIG. 2 is an explanatory view of a bag-shaped mesh member.

FIG. 3 is a schematic configuration diagram of a jet pump according to a second embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a fuel tank provided with a jet pump.

FIG. 5 is a schematic configuration diagram of a conventional jet pump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main chamber 2 Sub chamber 3 Fuel tank 4 Main pump 9 Return fuel 11, 31 Jet pump 12 Nozzle 13 Negative pressure chamber 14 Tip 15 Communication pipe 16 Mesh member 17 Fastening band 18 Oil film 21 Mesh member 32 Bar

 ──────────────────────────────────────────────────の Continuation of the front page (72) Inventor Hideki Ando 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation

Claims (1)

[Claims] 1. A nozzle for injecting return fuel into a main chamber of a fuel tank, and a nozzle disposed to cover the periphery of the nozzle and having a front end portion located below the main chamber and having a negative inside when return fuel is injected from the nozzle. In a jet pump comprising a negative pressure chamber that becomes a pressure and a communication path that extends from the sub chamber of the fuel tank and communicates with the negative pressure chamber to transfer fuel in the sub chamber by negative pressure in the negative pressure chamber, the tip of the negative pressure chamber A jet pump comprising an air inflow prevention means on a part side.