JPH0524351B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a fuel suction device for a fuel tank mounted on a vehicle such as an automobile.

Conventional technology Some automobile fuel tanks contain, for example,
As shown in Publication No. 57-109921, due to the structure of the part where the fuel tank is mounted, a bulge is formed inward on the bottom wall of the tank body. It is known to avoid interference between the bottom wall of the tank body and functional parts of the vehicle body.

Problem to be Solved by the Invention By forming a bulge in the bottom wall of the tank body, the main chamber and the sub-chamber are separated from each other in the substantially lower half of the tank body. In order to prevent fuel from remaining in either side, the feed pipe is branched into the main chamber side pipe and the auxiliary chamber side pipe through a switching valve, and when the fuel in the main chamber is consumed, the switching valve is closed. It must be activated so that the fuel in the pre-chamber is supplied. For this reason, not only is a switching valve required, but in order to automatically switch and operate this switching valve, a liquid level detection device is required in each of the main chamber and auxiliary chamber, a control unit is required, and an emergency It has been pointed out that there are problems with the product that make it expensive.

Therefore, the present invention does not require dedicated parts such as a switching valve or its operation control unit, and the main chamber
The present invention provides a fuel suction device for a fuel tank that can efficiently supply fuel in a subchamber.

Means for solving the problem: The suction port of the feed pipe is arranged in the main chamber separated from the lower half of the tank body, and a chamber is formed at the end of the return pipe protruding into the tank body. A nozzle protruding into the chamber is formed at the end of the return pipe, and a constriction part is formed below the nozzle of the chamber, and a tapered opening is formed following the constriction part, and the tapered opening is inserted into the main chamber. At the same time, the return pipe is provided with a relief valve that opens when the pressure in the return pipe exceeds a certain level and returns the fuel into the tank body,
A communication pipe having one end opening disposed near the bottom of the auxiliary chamber is communicated with and connected to the nozzle circumferential side of the chamber, and an ejector portion is formed at the connection portion between the chamber and the communication pipe.

Operation When the feed pump is driven, fuel in the main chamber is sucked in from the suction port of the feed pipe and supplied to the fuel supply device, and excess supplied fuel is returned to the tank body via the return pipe. The surplus fuel returned from the return pipe is forcefully ejected from the nozzle in the ejector section due to the discharge pressure of the feed pump. This jetting of fuel creates negative pressure around the nozzle of the chamber.
The fuel in the auxiliary chamber is sucked into the chamber through the communication pipe, and together with the jet from the nozzle, the flow velocity is increased by the constriction section and fed into the main chamber through the tapered opening.

Here, when the pressure inside the return pipe increases and reaches a certain level or more, the relief valve opens and the fuel inside the return pipe is returned to the tank body, thereby preventing the pressure inside the return pipe from increasing.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

In Figures 1 and 2, 1 indicates the tank body;
An inwardly bulging portion 2 is formed approximately at the center of the bottom wall, and a main chamber 3 and a sub chamber 4 are separated from each other at approximately the lower half of the tank body 1. A suction port of a feed pipe 5, for example, a filter 6 is disposed in the main chamber 3, and when a feed pump, which will be described later and is disposed outside the tank body 1, is driven, fuel in the main chamber 3 is passed through the filter 6. The fuel is then fed through a feed pipe 5 to a fuel supply device, which will be described later. Reference numeral 7 denotes a return pipe that is disposed protrudingly within the tank body 1 and returns surplus fuel that is not consumed by the fuel supply device into the tank body 1, and a chamber 9 is formed at the end of the return pipe 7. . A nozzle 8 protruding into the chamber 9 is formed at the end of the return pipe 7, and a constricted portion 10 and a tapered opening 11 are formed below the nozzle 8 of the chamber 9. Then, the tapered opening 11 is connected to the main chamber 3.
It is located inside.

Here, a branch port 7a is provided near the end of the return pipe 7.
A relief valve 12 is interposed at a, which opens when the internal pressure of the return pipe 7 becomes constant and returns the fuel in the return pipe 7 to the main chamber 3.

The relief valve 12 includes a casing 14 that is inserted into the branch port 7a, has its tip end sealed with an O-ring 13, and has a claw 14a in the center that engages with the engagement hole 7b of the branch port 7a.
The valve main body 16 is pressed by a spring 15 and comes into close contact with the seat surface 14b of the valve 4. By appropriately selecting the spring 15, an optimum valve opening pressure can be set.

Reference numeral 17 denotes a communication pipe having one end opening 17a disposed near the bottom of the subchamber 4, and this communication pipe 17 is connected to a port 9a protruding from the upper wall of the chamber 9.
An ejector portion 18 is formed at the connection portion between the chamber 9 and the communication pipe 17.

Further, an orifice 19 is provided at the upper side of the tapered opening 11, specifically at a location corresponding to the vicinity of the maximum liquid level of the main chamber 3.

According to the structure of the embodiment described above, when the feed pump 20 shown in FIG. In this fuel supply device 23, not all of the fuel fed from the feed pipe 5 is consumed, and excess fuel is returned into the tank body 1 via the return pipe 7. Here, since the end of the return pipe 7 is formed as a nozzle 8 in the chamber 9 constituting the ejector section 18, the fuel is transferred from the nozzle 8 to the constricted section 10 and the tapered opening 11 by the discharge pressure of the feed pump 20. It is ejected forcefully towards the target.

Therefore, a negative pressure is generated around the nozzle 8 in the chamber 9, and this negative pressure causes the fuel in the auxiliary chamber 4 to be sucked into the chamber 9 through the communication pipe 17, and together with the jet from the nozzle 8. Aperture part 10
The fuel in the auxiliary chamber 4 is fed into the main chamber 3, where an ejector action occurs, and the fuel in the auxiliary chamber 4 is transferred to the excess fuel tank body 1.
Upon returning inside, it is transferred to the main room.

Here, when the flow rate of the fuel flowing through the return pipe 7 is large, or when the fuel becomes high temperature and becomes a gas-liquid mixed state in which fuel vapor and liquid phase are mixed, the resistance due to the nozzle 8 becomes large. When the fuel pressure (back pressure) in the return pipe 7 rises above a certain value, the relief valve 12 provided at the branch port 7a of the return pipe 7 opens, and the fuel in the return pipe 7 is transferred to the main chamber 3. The pressure inside the return pipe 7 is prevented from increasing.

Therefore, in the case of cars with a carburetor specification, the pressure rise in the needle valve part or in the injector part in the case of cars with a fuel injection system as shown in Fig. 6 is prevented, and the increase in the pressure of the fuel supplied to the intake manifold is prevented. It keeps the mixture ratio constant and ensures smooth engine rotation.

Further, although the flow rate of the return pipe 7 differs depending on the engine installed, this can be countered by simply replacing the spring 15 of the relief valve 12. In addition, when replacing the spring 15, the engagement hole 7b of the branch port 7a and the claw 1 of the casing 14 are replaced.
This can be easily done by releasing the engagement of 4a.

In this way, by providing the relief valve 12, when the horizontal axis is the return flow rate and the vertical axis is the transfer flow rate or return pressure, as shown in Figs. 3 and 4, the return flow rate exceeds a certain value. Good ejector characteristics can be obtained in which the transfer flow rate and return pressure are maintained at constant values even when the temperature increases.

Note that in the event that the tip of the nozzle 8 becomes clogged with foreign matter, the ejector action will no longer occur and the fuel transfer action will no longer be performed, but since the return flow path is secured by the relief valve 12, there will be no adverse effect on the engine. do not have.

Furthermore, once the above-mentioned fuel transfer action occurs, even if the feed pump 20 stops, the main chamber 3
If the fuel level on the side is lower than the fuel level on the subchamber 4 side, the system from the chamber 9 to the communication pipe 17 is filled with fuel, so due to the siphon effect,
The above-mentioned fuel transfer is continued until the fuel level on the main chamber 3 side becomes the same level as the fuel level on the auxiliary chamber 4 side.
In the opposite case, that is, when the fuel level on the main chamber 3 side is higher than the fuel level on the auxiliary chamber 4 side, the siphon effect will occur because the orifice 19 is located above the tapered opening 11 of the chamber 9. Therefore, there is no backflow of fuel from the main chamber 3 side to the auxiliary chamber 4 side. In FIG. 6, 21 represents a fuel damper, 22 represents a fuel filter, and 24 represents a pressure regulator.

In the embodiment shown in FIG. 5, one end opening 17a of the communication pipe 17 is arranged in a rotating tank fixed to the bottom wall of the subchamber 4. In this way, the connecting pipe 1
By arranging the opening 17a at one end of 7 in the turning tank 25, when the remaining fuel level becomes low, the fuel liquid level will tilt as shown by chain lines a and b in the same figure due to a sudden turn of the vehicle. Even during this sharp turn, the amount of fuel that can be sucked into the turning tank 25 can be ensured, and the transfer of fuel from the sub-chamber 4 side to the main chamber 3 side can be continued even during this sharp turn.

Note that when a feed pump is disposed in the main chamber 3 to constitute an in-tank pump type fuel tank, the suction port of the feed pipe becomes the inlet of the feed pump. In addition, in the embodiment described above, the tapered opening 11 of the chamber 9 is submerged in the fuel in the main chamber 3, but if the tapered opening 11 is placed above the fuel liquid level, there will be a hole above the tapered opening 11 to prevent backflow. There is no need to provide an orifice 12.

Effects of the Invention As described above, according to the present invention, the fuel in the main chamber is led out to the fuel supply device by driving the feed pump, and at the same time, the fuel in the auxiliary chamber is smoothly transferred to the main chamber side by the ejector action of the ejector part. In addition, it does not require any special electrical parts like in the past, so it is structurally simple, and it also has a great practical effect in that it can prevent pressure rise on the engine side. have

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing one embodiment of the present invention, FIG. 2 is an enlarged sectional view of the ejector section, and the third and fourth
The figures are graphs showing the relationship between the return flow rate and the transfer flow rate or return pressure, FIG. 5 is a sectional view of a main part of another embodiment, and FIG. 6 is a fuel supply system diagram. 1...Tank body, 2...Bulging part, 3...Main chamber, 4...
Sub-chamber, 5...Feed pipe, 6...Suction port, 7...Return pipe, 8...Nozzle, 9...Chamber, 10
... Throttle part, 11... Tapered opening, 12... Relief valve, 17... Communication pipe, 17a... One end opening, 1
8...Ejector section.

Claims (1)

[Claims] 1. In a structure in which a bulge is formed on the bottom wall of the tank body to separate a main chamber and a sub-chamber in substantially the lower half of the tank body, the suction port of the feed pipe is arranged near the bottom of the main chamber. At the same time, a chamber is formed at the end of the return pipe protruding into the tank body, a nozzle protruding into the chamber is formed at the end of the return pipe, and a constriction part is formed below the nozzle of the chamber, and a constriction part is formed below the nozzle of the chamber. A tapered opening is formed following the constriction part, and the tapered opening is arranged in the main chamber, and a relief is provided in the return pipe that opens when the pressure in the return pipe exceeds a certain level and returns the fuel into the tank body. A valve is provided, and a communicating pipe having one end opening disposed near the bottom of the auxiliary chamber is connected in communication with the nozzle circumferential side of the chamber, and an ejector portion is configured at the connecting portion between the chamber and the communicating pipe. A fuel suction device for a fuel tank.