JPH0339199B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a jet pump used in a vehicle fuel supply system equipped with a main fuel pump that supplies fuel in a fuel tank with two bottoms to a vehicle engine. Regarding.

These types of fuel tanks have two recesses at the bottom, and when the fuel gets low, a small amount of fuel accumulates in each recess, and the fuel tank is divided into two tanks by a partition wall. There are two types of fuel tanks: a separated two-layer integrated type and a type in which two fuel tanks are installed in separate locations. It can also be applied to feeding devices.

Further, such fuel supply systems for vehicles include a so-called main type and a return type (both of which will be described in detail later), and the present invention is applicable to either type.

(Prior art) When a fuel pump is installed in the above-mentioned type of fuel tank, for example, if the fuel pump is installed at one of the two bottoms, when the fuel becomes low, it is possible to suck up fuel from the other bottom. Therefore, it becomes necessary to use two pumps of the same type. However, this is undesirable as it increases the cost, so one main fuel pump and a jet pump, which has a simpler structure and is therefore cheaper, are used, and the main fuel pump sucks up the fuel from the first bottom. A jet pump moves the fuel from the second bottom to the first bottom. More specifically, the main fuel pump is disposed inside the first bottom of the fuel tank or in the middle of a pipe outside the fuel tank, and supplies a portion of the sucked up fuel to the vehicle engine outside the fuel tank, and supplies the remainder of the fuel to the fuel tank. The jet pump is operative to return the first bottom portion of the fuel tank via the return passageway, and a jet pump is connected to the fuel return passageway and is operatively operated by the fluid energy of the fuel flowing within the fuel return passageway to return the first bottom portion of the fuel tank. Transferring the bottom fuel to the first bottom.

The jet pump has one end connected to the fuel return passage near the discharge port of the main fuel pump and the other end connected to the fuel return passage (main type), and a return passage from the pressure regulator attached to the fuel injection engine. (return method), 2
It is used in both methods.

(Problem to be Solved by the Invention) When a vehicle engine is a carburetor type engine and a main system is adopted, the main fuel is used to maintain a substantially constant amount of fuel in the fuel chamber of the carburetor. It is necessary to regulate the discharge pressure of the pump to below a predetermined value, and if the vehicle engine is a fuel injection type engine and a main system is adopted, the pressure from the main fuel pump to the pressure regulator When the piping becomes clogged, it is necessary to regulate the pressure inside the piping to below a predetermined value. In order to meet these demands, conventionally, the main fuel pump itself has been provided with a pressure relief mechanism, or a relief valve has been provided separately near the main pump's discharge port. The structure becomes more complicated and the number of parts increases, both of which cause increased manufacturing costs.

Additionally, if the vehicle engine is a carburetor type engine and a return method is adopted, if an accident occurs where the jet pump nozzle becomes clogged, the pressure in the fuel return passage will rise and the carburetor Because of the inconvenience of increasing the amount of fuel in the fuel chamber, the diameter of the nozzle of the jet pump had to be increased accordingly. In addition, if the vehicle engine is a combustion injection type engine and a return method is adopted, the pressure of the fuel that passes through the pressure regulator and is returned to the fuel tank must be set to a predetermined pressure or less. (because it does not affect the fuel injection pressure), and therefore the diameter of the jet pump nozzle had to be designed to be quite large. In this way, when designing a jet pump, the fact that there are various restrictions regarding the size of the nozzle diameter causes the inconvenience of a lack of freedom in the design of the jet pump, and it is necessary to design separate jet pumps for the main method and return method. There was a problem that I had to design.

The present invention seeks to provide a jet pump that can overcome the various problems mentioned above.

(Means for Solving the Problems) The jet pump provided by the present invention is connected to the fuel return passage of the vehicle fuel supply system as described above, operates by the fluid energy of the fuel flowing in the fuel return passage, and is operated by the fluid energy of the fuel flowing in the fuel return passage. This is a jet pump for transferring fuel from the second bottom of the tank to the first bottom. This jet pump includes a nozzle connected to a fuel return passage, a ventilate pipe facing the nozzle and discharging fuel to a first bottom of the fuel tank, and a negative pressure chamber formed between the nozzle and the ventilate pipe. , a suction passage connected to the negative pressure chamber and communicating with the second bottom of the fuel tank, and a suction passage disposed upstream of the nozzle, from which the fuel pressure is discharged from the fuel return passage when the fuel pressure in the fuel return passage exceeds a predetermined value. It is characterized by being equipped with a relief valve for releasing fuel.

(Function) Since the jet pump itself is equipped with a relief valve, the pressure in the fuel return passage is always regulated to a predetermined value by the relief valve.

(Example) First, in order to facilitate understanding, the details of the configuration of the jet pump with a relief valve according to the present invention itself will be described later, and the structure and operation of a vehicle fuel supply system to which the present invention is applied will be explained. First, an overview will be explained.

Referring to FIG. 4, there is shown a block diagram of an example of a vehicle fuel supply system using the jet pump 23 with a relief valve of the present invention. In this example, vehicle engine 22 is a carburetor engine, and near the outlet of main fuel pump 15,
A part of the discharged fuel is introduced into the jet pump 23 via the fuel return passage 27 (this method is referred to as the "main method"). The fuel tank 14 has a first bottom portion 32a and a second bottom portion 32b, and has a structure in which fuel remains in each of the first bottom portion 32a and the second bottom portion 32b when a small amount of fuel remains in the tank. ing. Main fuel pump 15
When the switch 30 is closed, the in-vehicle battery 31
It consists of a DC motor driven by a power source consisting of a DC motor, and a pump section (for example, a regeneration pump) driven by a rotating shaft of the DC motor. The main fuel pump 15 sucks up the fuel in the fuel tank 14 through a dust removal filter 24 made of resin or wire mesh, and discharges the fuel into a discharge pipe 26 . A portion of the discharged fuel passes through the main throttle 17 and the float 20 with a needle valve to the fuel chamber 1 of the carburetor.
9 and supplied to the vehicle engine 22.
The fuel in the fuel chamber 19 is maintained at a substantially constant amount by the float 20 with a needle valve, and excess fuel from the discharge pipe 26 passes through the return throttle 18 and is directly returned to the fuel tank 14 via the pipe 29. Further, the remainder of the fuel discharged from the main fuel pump 15 is immediately introduced into the jet pump 23 through the fuel return passage 27. The jet pump 23 is operated by the fluid energy of the fuel flowing in the fuel return passage 27 to transfer the fuel in the second bottom part 32b through the filter 25 and the pipe 28 into the first bottom part 32a. The main fuel pump 15 used in the system shown in FIG. 4 is a low-pressure or medium-pressure pump.

Referring to FIG. 5, there is shown a configuration diagram of another example of a vehicle fuel supply system using the relief valve equipped jet pump 23 of the present invention. In this figure, the same reference numerals as in FIG. 4 indicate the same or equivalent parts.

In this device, the vehicle engine 22a is a fuel injection engine, and fuel discharged from the main fuel pump 16 is supplied to the vehicle engine 22a via a discharge pipe 26, and surplus fuel is discharged from the pressure regulator 21. The fuel is introduced into the jet pump 23 through the fuel return passage 27a, which is a return passage (referred to as the "return method").

In this example, since the vehicle engine 22a is a fuel injection engine, the main fuel pump 16 is for medium pressure or high pressure;
The pressure regulator 21 is disposed in the fuel supply system so that the fuel discharged from the engine is injected at a predetermined pressure into the intake system of the engine.

Next, referring to FIG. 1, there is shown a detailed structure of a jet pump 23 which is an embodiment of the present invention.

This jet pump 23 includes an inlet housing 1 having a pipe 2 connected to a fuel return passage 27 or 27a shown in FIG. 4 or 5, a nozzle 3, and a fuel relief hole 4; It has an outlet housing 5 connected near the nozzle 3. The outlet housing 5 includes a negative pressure chamber 7 that communicates with the nozzle 3 and a ventilary pipe 6 that includes a diffuser section 6a that delivers fuel from the negative pressure chamber 7 and converts velocity energy into pressure energy. A suction passage 8 communicating with the pressure chamber 7 is provided. The ventilate pipe 6 discharges fuel to the first bottom 32a of the fuel tank, and the suction passage 8 is connected to a pipe 28 (FIGS. 4 and 5).

A relief valve constituted by a ball valve 13 made of gasoline-resistant rubber is pressed by a spring 12 against a valve seat formed by the outer edge of the fuel relief hole 4. A cap 9 having a spring positioning projection 10 and a plurality of relief holes 11 is mounted on the inlet housing 1.

The inlet housing 1, outlet housing 5, and cap 9 are all made of thermoplastic resin, and can be assembled by ultrasonic welding.

Since the jet pump 23 of the present invention has the above-mentioned configuration, when fuel is introduced into the pipe 2 from the fuel return passage 27 (FIG. 4) or 27a (FIG. 5), the fuel flows through the nozzle 3. is injected at high speed, and at this time, a negative pressure is formed in the negative pressure chamber 7, and this negative pressure causes the fuel in the second bottom portion 32b of the fuel tank to be sucked from the suction passage 8. The sucked fuel is discharged through the ventilate tube 6 into the first bottom portion 32a of the fuel tank. Thus, the second bottom portion 32
The fuel inside b is transferred into the first bottom part 32a.

Here, when the pressure of the fuel in the fuel return passage 27 or 27a exceeds a predetermined value, the relief valve 13 disposed on the upstream side of the nozzle 3 is pushed outward against the pressing force of the spring 12 to provide relief. The hole 4 is opened, so that the fuel is discharged from the pipe 2 through the relief hole 4 and the plurality of relief holes 11 to the outside, that is, into the first bottom part 32a. Therefore, the fuel pressure in the fuel return passage 27 or 27a does not rise above a predetermined value. This point will be explained in more detail in relation to the main method and return method shown in FIGS. 4 and 5.

In the fuel supply system of the type shown in FIG. 4, when the fuel in the fuel chamber 19 reaches a certain amount, a float 20 with a needle valve
has been closed to prevent further fuel from entering. However, if the pressure of fuel from the main fuel pump 15 is higher than a predetermined value, the float 20
A force greater than the force pushing up the needle valve part acts on the float 20 with a needle valve, and the float is pushed down, causing excess fuel to flow into the fuel chamber 19.
As a result, the air-fuel ratio in the engine tends to become too rich. but,
The jet pump 23 of this embodiment has a relief valve 13.
This relief valve releases the pressure when the pressure of the fuel in the fuel return passage 27 exceeds a predetermined value, and therefore the pressure of the fuel in the discharge pipe 26 is regulated to below the predetermined value. , the problem that the air-fuel ratio becomes too rich does not occur.

Also in the fuel supply device of the type shown in Fig. 5,
If the jet pump 23 were not installed, the fuel after passing through the pressure regulator 21 would return to the fuel tank through the return passage and its pressure would be released to the atmosphere. Since it is connected to the fuel return passage 27a, the fuel passing through the fuel return passage 27a must pass through the nozzle of the jet pump 23. The pressure of this return fuel needs to be set so as not to exceed the minimum operating pressure of the pressure regulator 21 so as not to affect the injector injection pressure. Therefore, when a conventional jet pump is used, the diameter of its nozzle must be larger than that of the jet pump used in the main system. However, since the jet pump 23 of this embodiment is equipped with the relief valve 13, there is no need to make the diameter of the nozzle larger than in the case of the main system, and the action of the relief valve 13 allows the fuel return passage to be closed. 27a
The pressure of the fuel inside is controlled so as not to exceed the minimum operating pressure of the pressure regulator 21. Therefore, the jet pump can be of the same design as that used in the main method.

Furthermore, if the jet pump is not equipped with a relief valve, when the vehicle is idling and the fuel consumption of the vehicle engine is low, the fuel will pass through the pressure regulator 21 and be returned to the fuel tank 14. The amount of fuel being transferred becomes larger, and the transfer capacity of the jet pump becomes excessive, resulting in an unnecessary transfer of a large amount of fuel from the second bottom portion 32b of the tank to the first bottom portion 32a. 13 to regulate the flow rate passing through the nozzle 3, the transfer capacity of the jet pump does not increase excessively even during idling.

FIG. 2 is a longitudinal sectional view of a jet pump 23a which is another embodiment of the present invention. In this embodiment, a relief valve consisting of a flat valve body 13a having an annular convex portion 13b is used instead of a ball valve.

FIG. 3 is a longitudinal sectional view of a jet pump 23b which is still another embodiment of the present invention. In this embodiment, a relief valve consisting of a thin plate-shaped valve body 13c which is heated and attached to the inlet housing 1 by means of a projection 14 is used.

In FIGS. 2 and 3, the same reference numerals as in FIG. 1 indicate the same or equivalent parts, so other explanations will not be repeated.

(Effects of the Invention) Since the jet pump of the present invention is equipped with a relief valve itself, the main fuel pump itself may be provided with a relief valve, or a separate relief valve may be connected to the discharge port of the main fuel pump. Since there is no need to do this, manufacturing costs are significantly reduced. Furthermore, even when the return method is adopted, the nozzle diameter of the jet pump does not need to be made large, and the nozzle diameter can be designed with a large degree of freedom in order to match the desired performance of the jet pump. The same design as the jet pump used when using the main method can also be used for the return method.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a jet pump which is an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of a jet pump which is another embodiment of the invention, and FIG. 3 is a longitudinal sectional view of a jet pump which is another embodiment of the invention. A longitudinal sectional view of a certain jet pump, FIGS. 4 and 5, respectively, are configuration diagrams showing an example of a vehicle fuel supply system in which the jet pump of the present invention is used. 1...Inlet housing, 2...Pipe,
3...Nozzle, 4...Relief hole, 5...Outlet housing, 6...Venture tube, 6a
... Diff user part, 7 ... Negative pressure chamber, 8 ... Suction passage, 9 ... Cap, 12 ... Spring, 1
3, 13a, 13c... Relief valve, 14... Fuel tank, 15, 16... Main fuel pump, 17...
...Main aperture, 18...Return aperture, 19...
Fuel chamber, 20...Float with needle valve,
21...pressure regulator, 22, 22a
...Vehicle engine, 23, 23a, 23b...Jet pump, 24, 25...Filter, 26...
...Discharge pipe, 27, 27a...Fuel return passage,
28...Piping, 29...Piping, 30...Switch, 31...Battery, 32a...First bottom part, 3
2b...Second bottom.

Claims (1)

[Scope of Claims] 1. A first bottom part and a second bottom part are separated, and when fuel remaining inside becomes small, fuel remains in each of the first bottom part and the second bottom part. a fuel tank having a structure, and a fuel tank disposed within the first bottom portion of the fuel tank or in the middle of a pipe outside the fuel tank to suck up fuel from the tank and supply a part of it to a vehicle engine outside the fuel tank; a main fuel pump that returns the remainder of the sucked up fuel to the first bottom portion of the fuel tank via a fuel return passage; actuated by the fluid energy of flowing fuel, said second
A jet pump for transferring fuel from a bottom portion to the first bottom portion, the jet pump comprising: a nozzle connected to the fuel return passage; and a ventilate pipe facing the nozzle and discharging fuel to the first bottom portion of the fuel tank. a negative pressure chamber formed between the nozzle and the ventilate pipe; a suction passage connected to the negative pressure chamber and communicating with the second bottom of the fuel tank; A jet pump for a fuel supply system of a vehicle, comprising a relief valve for releasing fuel from the fuel return passage when the fuel pressure in the return passage exceeds a predetermined value.