JP2001050131A - Turbine type fuel pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve high temperature performance by suppressing generation of vapor and to compulsorily discharge generated vapor. SOLUTION: When discharge pressure of a fuel pump 1 is high pressure, fuel supply from the pump 1 to a fuel injection device 6 is continued and a bypass passage 7 is closed by a pressure switching valve 8. At this time, a pressure regulator 5 supplies fuel of fixed pressure to the fuel injection device 6, and when excessive fuel is returned to a fuel tank 2 via a passage 10, fuel including vapor within a fuel chamber 3 is discharged to the fuel tank 2 by a jet pump 11. When discharge pressure of the fuel pump 1 is lowered to prescribed pressure by generation of vapor, the bypass passage 7 is opened by a pressure switching valve 8. As a result that a part of the discharged fuel is returned within the fuel tank 2, a fuel oil temperature is cooled and discharge pressure is recovered to the high pressure state in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-line turbine fuel pump provided with measures against vapor, air bubbles, and the like (hereinafter referred to as vapor, etc.).

[0002]

2. Description of the Related Art In an electronically controlled fuel injection system for an internal combustion engine, a turbine type fuel pump is provided in an in-line type in a fuel chamber to discharge vapor generated in the fuel pump and the fuel chamber. Is
There is one disclosed in U.S. Pat. No. 5,647,331. FIG.
FIG. 1 is a block diagram of such a system. As shown in FIG. 1, the system includes a fuel tank 100 and a fuel chamber 101 communicating with the fuel tank 100.
And a fuel injection device 105 connected to the fuel pump 102 via a fuel filter 103 and a pressure regulator 104. A configuration 104 is connected to the fuel chamber 101 via a communication path 106. And
By the pressure regulator 104, fuel at a constant pressure is supplied to the fuel injection device 105, and when the pressure becomes too high, excess fuel and vapor are returned to the fuel chamber 101 together.

[0003]

The above-mentioned vapor and the like are remarkably generated when the temperature of the fuel oil is high. If so-called vapor lock is caused, the discharge pressure of the fuel pump is reduced, and particularly, high-temperature starting is performed. Performance deteriorates.
Therefore, when the fuel pump is of a turbine type, it has good high-temperature startability in combination with the fact that it does not have a so-called self-priming ability to automatically send out the air in the suction pipe to the discharge pipe side by the action of the impeller at startup. This has been a fundamental problem for turbine type pumps. Therefore, even if a measure for removing the generated vapor or the like is taken as in the above-described example, this alone is not sufficient, and it is desired to suppress the generation of the vapor or the like.

An object of the present invention is to provide a turbine type fuel pump in which the generation of vapor and the like is suppressed and the high-temperature performance is improved. In addition, the object of the present invention, in addition to the above objects,
An object of the present invention is to provide a turbine fuel pump for forcibly discharging generated vapor and the like.

[0005]

According to a first aspect of the present invention, there is provided a turbine type fuel pump.
A fuel pump that is disposed in a fuel chamber communicating with the fuel tank and supplies the fuel in the fuel tank to the fuel injection device, constantly monitors the discharge pressure of the fuel pump,
When the discharge pressure is low, there is provided a vapor lock preventing means for returning a part of the discharged fuel into the fuel tank, and the vapor lock preventing means functions as a fuel oil temperature cooling device. Thereby, generation of vapor and the like can be suppressed and high-temperature performance can be improved. Therefore, it is possible to improve the high-temperature starting performance, which is a problem with this kind of pump, and of course, it is possible to expand the use environment of this kind of pump, for example, to use the pump horizontally in a severe environment. Become. For example, the vapor lock prevention unit that performs such a function forms a flow path that continues to supply fuel from the fuel pump to the fuel injection device when the discharge pressure is high (at this time, the fuel pump is in a normal operation state). This can be achieved by forming a flow path for returning a part of the fuel discharged from the fuel pump into the fuel tank when the discharge pressure is reduced to a predetermined pressure due to generation of vapor or the like. By the way, if a heat exchanger or the like is attached to this flow path to forcibly cool the flow path, it goes without saying that the cooling effect is further increased.

In a turbine type fuel pump according to a second aspect of the present invention, the vapor lock preventing means connects a discharge side of the fuel pump and a fuel tank by a bypass passage, and a pressure switching valve is disposed in the bypass passage. With such a pressure switching valve, the above-mentioned flow paths can be easily formed in accordance with the operation state of the fuel pump.

A turbine type fuel pump according to a third aspect of the present invention has both functions of suppressing the generation of vapor and the like and forcibly discharging the generated vapor and the like. When supplied to the fuel injection device via a pressure regulator, in addition to the above vapor lock prevention means, a jet pump formed in a flow path connecting the pressure regulator and the fuel tank, having a communication passage opening to the fuel chamber. It is provided. Such a jet pump preferably has, for example, a jet pump structure described in Japanese Patent Application No. 11-58307. According to the jet pump having such a structure, the fuel fluid flowing through the flow path is provided with a fuel chamber through a communication passage. Since the fuel containing the vapor and the like inside can be sucked and discharged to the fuel tank, not only the structure itself can be made simple and compact, but also a mode of forcibly discharging the vapor and the like can be adopted. In addition, the fuel oil temperature can be cooled.

[0008]

FIG. 1 shows an example of an embodiment of the present invention.
This will be described with reference to FIGS. The turbine fuel pump 1 according to the present embodiment is an in-line type having both functions of suppressing generation of vapor and the like and discharging generated vapor and the like. FIG. 1 is a block diagram of an electronic control fuel injection system using the fuel pump 1.
This system includes a fuel tank 2 for storing fuel, a fuel chamber 3 communicating with the fuel tank 2, a fuel pump 1 disposed in a fuel liquid in the fuel chamber 3, and a fuel pump The fuel injection device 6 is connected to the discharge side of the fuel cell 1 via a fuel filter 4 and a pressure regulator 5. And this fuel pump 1
In order to suppress generation of vapor and the like, a bypass passage (vapor lock preventing means) 7 connecting the discharge side of the fuel tank 2 and the fuel tank 2 is provided.
A pressure switching valve (vapor lock prevention means) 8 is provided, and a communication passage 9 is opened in the fuel chamber 3 for discharging generated vapor and the like. The pressure regulator 5 and the fuel tank 2 are connected to each other. A jet pump 11 is provided in a flow path 10 for connection.

The pressure switching valve 8
Forms a flow path for continuing the supply of fuel to the fuel injection device 6 when the discharge pressure of the fuel pump 1 is high.
When the discharge pressure is reduced to a predetermined pressure, a flow path for returning a part of the discharge fuel into the fuel tank 2 can be formed, and the flow path is not particularly limited as long as it is simple. . In addition, the jet pump 11 has a flow path 10
The fuel containing vapor and the like in the fuel chamber 3 is sucked into the flow path 10 by the fuel fluid flowing through the communication path 9 and is forcibly discharged to the fuel tank 2. An outline of the structure is as follows. An elongated throttle pipe (not shown) having a nozzle-shaped tip is arranged in the flow path 10, and a negative pressure is applied to a space surrounded by the outer circumference of the throttle pipe and the inner wall of the flow path 10. A chamber (not shown) is formed, and the communication path 9 is communicated with the negative pressure chamber so that the negative pressure chamber opens to the upper part of the fuel chamber 3 through the communication path 9. The fuel including the vapor in the fuel chamber 3 is sucked through the communication passage 9 by the high-speed flow passing through the nozzle portion of the throttle pipe, and is discharged to the fuel tank 2.

Next, the operation of the system using the fuel pump 1 will be described. When the fuel pump 1 is in a normal operation state, that is, when the discharge pressure of the fuel pump 1 is high, the fuel is supplied from the fuel pump 1 to the fuel injection device 6 via the fuel filter 4 and the pressure regulator 5. While continuing, the bypass passage 7 is closed by the pressure switching valve 8. At this time, the pressure regulator 5 operates so that fuel at a constant pressure is supplied to the fuel injection device 6, and when excess fuel is returned to the fuel tank 2 through the flow path 10, the fuel pump The fuel containing the vapor and the like in 3 is discharged to the fuel tank 2.

When the fuel pump 1 is not in a normal operation state, that is, when its discharge pressure is reduced to a predetermined pressure due to generation of vapor or the like, the pressure switching valve 8
As a result, a part of the discharged fuel is returned to the fuel tank 2 and a flow path for cooling the fuel oil temperature is formed. Can return to the state. Then, depending on the set pressure of the pressure switching valve 8 for opening the bypass passage 7 and the set pressure of the pressure regulator 5 for returning excess fuel to the fuel tank 2, the regulator 5
When excess fuel is returned to the fuel tank 2, fuel including vapor in the fuel chamber 3 can be discharged to the fuel tank 2 by the jet pump 11.

[0012]

According to the turbine type fuel pump of the present invention, high temperature performance can be improved by suppressing generation of vapor and the like. According to the turbine fuel pump of the present invention, in addition to suppressing the generation of vapor and the like, the generated vapor and the like can be forcibly discharged.

[Brief description of the drawings]

FIG. 1 is a block diagram of an electronic control fuel injection system using a turbine fuel pump according to the present embodiment.

FIG. 2 is a block diagram of an electronically controlled fuel injection system using a conventional turbine fuel pump.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 fuel pump 2 fuel tank 3 fuel chamber 5 pressure regulator 6 fuel injection device 7 bypass passage (vapor lock prevention means) 8 pressure switching valve (vapor lock prevention means) 9 communication path 10 flow path 11 jet pump

Claims (3)

[Claims] 1. A turbine type fuel pump disposed in a fuel chamber communicating with a fuel tank and for supplying fuel in the fuel tank to a fuel injection device, the discharge pressure of which is constantly monitored. A turbine type fuel pump comprising vapor lock prevention means for returning a part of the discharged fuel into the fuel tank when the discharge pressure is low. 2. The fuel supply system according to claim 1, wherein the vapor lock preventing means connects a discharge side of the fuel tank to the fuel tank by a bypass passage, and a pressure switching valve is disposed in the bypass passage. A turbine type fuel pump as described. 3. When the fuel in the fuel tank is supplied to the fuel injection device via a pressure regulator, the fuel tank has a communication passage opening to the fuel chamber, and connects the pressure regulator to the fuel tank. 3. The turbine type fuel pump according to claim 1, further comprising a jet pump formed in the flow path.