JPH0287000A - Jet pump - Google Patents

Abstract

PURPOSE:To bring optimal suction performance into full play by setting a diameter of a throttle part, a distance from a nozzle tip to a diffuser throttle part and length of a diffusion to each specified relation in regard to a nozzle bore jetting a driving fluid. CONSTITUTION:A jet pump 1 is provided with a driving pipe 5, making return fuel out of an engine 3 run out as a driving fluid, and a nozzle 6 spraying this return fuel. Likewise, it is equipped with a diffuser 8 fitted with a throttle part 7a throttle the return fuel and a discharge port 7b discharging the fuel, a vacuum chamber 9 and a suction pipe 11 connected to this vacuum chamber 9. In the above constitution, when a bore of the nozzle 6 is set to (d), a diameter D of the throttle part 7a is set to D<=2d, a distance l from a tip of the nozzle 6 to the throttle part 7a to l>=2d and length L of the diffuser 8 to L>=2.5l, respectively.

Description

[Detailed description of the invention] [Purpose of the invention]

(Industrial Application Field) The present invention provides, for example, in a two-tank fuel tank for automobiles, by returning fuel from the carburetor to the fuel tank.
It relates to jet pumps used to transfer fuel from one tank to another tank. (Prior art) Conventionally, the above-mentioned jet pump was manufactured in September 1988.
There was a jet pump described on page B-125 of "Service Bulletin No. 588" published by Nissan Motor Co., Ltd. on the 1st of every month. The jet pump is provided above one tank in a two-tank fuel tank, and includes a drive pipe through which return fuel (driving fluid) from the engine flows, and a drive pipe provided at the tip of the drive pipe to flow the return fuel. a diffuser having a nozzle for injecting the fuel, a constriction part concentrically with the nozzle for squeezing the return fuel injected from the nozzle, and a negative pressure state by converting the fuel from the velocity head to the pressure head in the diffuser. It has a structure that includes a negative pressure chamber and a suction pipe that is connected to the negative pressure chamber and sucks in fuel (driven fluid) from another tank of the two-tank fuel tank. When the jet pump injects the return fuel from the nozzle, the velocity head of the return fuel is converted into a pressure head at the constriction part of the diffuser, so that the inside of the negative pressure chamber becomes a negative pressure state and the other side is injected through the suction pipe. At the same time, the return fuel injected from the nozzle and the fuel sucked in through the suction pipe are mixed, and the mixture is discharged from the diffuser into one tank, and the fuel in the other tank is mixed with the fuel in the other tank. This is what controls the action of pumping water into the tank. (Problem to be Solved by the Invention) However, the above-mentioned conventional jet pumps have different diameters of the nozzle, diameter of the constriction part, and The distance from the nozzle tip to the diffuser constriction was set, but the cross-sectional area of the fuel injected conically from the nozzle determines the suction performance such as the fuel suction start time and suction flow rate. If the width of the fuel injected in a conical shape becomes too wide, there is a problem in that the fuel flows back into the negative pressure chamber, reducing suction performance. In addition, when the jet pump is installed at the bottom of the fuel tank, the fuel always remains in the jet pump, so when the fuel temperature rises to about 40°C to so'c,
There was a problem in that a paper lock phenomenon occurred and fuel could not be sucked up. (Object of the Invention) Therefore, an object of the present invention is to provide a jet pump that can obtain optimal suction performance regardless of the location where it is installed within a fuel tank.

[Structure of the invention]

(Means for Solving the Problems) The jet pump according to the invention described in claim (1) includes a nozzle provided at the tip of a drive pipe through which a driving fluid flows and jets out the driving fluid, and a nozzle disposed at a position concentric with the nozzle. a diffuser having a constriction portion that throttles the driving fluid injected from the nozzle;
In the jet pump, the jet pump includes a negative pressure chamber that becomes a negative pressure state by converting the driving fluid in the diffuser from a velocity head to a pressure head, and a suction pipe that connects to the negative pressure chamber and sucks the driven fluid. When the diameter of the nozzle is d, the diameter of the constriction part is set as D≦2d, the distance *i from the nozzle tip to the constriction part of the diffuser is set as ≧2d, and the length L of the diffuser is set as L≧2.5l. The present invention is characterized by having a configuration that provides a means for solving the problems of the prior art. Furthermore, the □jet pump according to the invention described in claim (2) includes:
The jet pump according to claim (1) is characterized in that the distance from the nozzle tip to the constriction part of the diffuser is set to ≦d, and the length L of the diffuser is set to L≧2. This configuration is used as a means to solve the conventional problems. (Function) The jet pump according to the invention set forth in claim (1) has the above-described structure, and has the effect of increasing the fuel suction flow rate when it is installed, for example, above the fuel tank. . Further, since the jet pump according to the invention described in claim (2) has the above-described configuration, it is not affected by the paper lock phenomenon even if the fuel temperature rises, for example, when it is installed on the lower side of the fuel tank. This has the effect of sucking up fuel without causing any damage. (Example) Hereinafter, the present invention will be explained based on the drawings. 1 to 4 are diagrams showing an embodiment of the jet pump according to the present invention, and FIG. 1 is a diagram showing the structure of the jet pump. In FIG. 1, 1 is a jet pump. As shown in FIG. 2, this jet pump 1 is installed in one tank 2a of a two-tank fuel tank 2, and is connected to a return pipe 4 that returns fuel from an engine 3. A drive pipe 5 through which fuel flows as a drive fluid, and the drive pipe 5
a nozzle 6 provided at the tip of the nozzle 6 for injecting the return fuel;
and a diffuser 8 having a constriction part 7a that is concentric with the nozzle 6 and that throttles the return fuel injected from the nozzle 6, and a discharge lower b that discharges the fuel into one tank 2a of the fuel tank 2; A negative pressure chamber 9 becomes a negative pressure state by converting the return fuel from the diffuser 8 from a velocity head to a pressure head, and the fuel (driven fluid) in the other tank 2b of the fuel tank 2 is transferred to the one tank 2a. A suction pipe 1 connected to a connecting pipe 10 and connected to the negative pressure chamber 9.
1, and the jet pump 1 includes:
When the return fuel is injected from the nozzle 6, the inside of the negative pressure chamber 9 becomes a negative pressure state, and the fuel in the other tank 2b of the fuel tank 2 is transferred to one tank 2a through the connecting pipe 10 and the suction pipe 11.
It has the effect of transferring Next, when the diameter of the nozzle 6 of the jet pump 1 described above is d, the diameter of the constriction part 7a is set to D-2d, and the constriction part 7a of the diffuser 8 is
A case will be explained in which the distance to the end is set to 2.5d, and the length of the diffuser 8 is set to L=3d. When this jet pump 1 is installed above the fuel tank 1 as shown in Fig. 2, the suction flow rate gradually increases as the fuel temperature rises, as shown by the circle in Fig. 3. It continues to decline. Furthermore, when the jet pump 1 is installed below the fuel tank 2, as shown by the broken line in FIG. 2, as the fuel temperature increases, as shown by the circle in FIG. It can be seen that the suction flow rate suddenly decreased and a paper lock phenomenon occurred. Next, when the diameter of the nozzle 6 of the jet pump 1 is d, the diameter of the constriction part 7a is set to D=2d, and the distance from the tip of the nozzle 6 to the constriction part 7a of the diffuser 8 is l=o, 9d. A case will be described in which the length L of the diffuser 8 is set to L=3d. When this jet pump 1 is installed above the fuel tank 2, as shown by the solid line in Fig. 2, the suction flow rate increases as the fuel temperature increases, as shown by the Δ mark in Fig. 3. gradually decreases, but at this time jet pump 1
Since there is no fuel remaining in the negative pressure chamber 9, if there is little negative pressure generated in the negative pressure chamber 9, the suction efficiency will decrease and the suction flow rate will decrease, as shown by the circle in Figure 3. The suction performance will be lower than that of the original. Furthermore, when the jet pump 1 is installed below the fuel tank 2, as shown by the broken line in FIG. 2, as the fuel temperature increases, as shown by the Δ mark in FIG. The suction flow rate gradually decreases, but since the fuel remains in the jet pump 1 at this time, even if the generation of negative pressure in the negative pressure chamber 9 is small, ○ in FIG. It becomes possible to obtain the same suction flow rate as shown by the mark. Therefore, it can be seen that the jet pump 1 indicated by the circle in FIGS. 3 and 4 has better suction performance when it is provided above the fuel tank 2. Furthermore, it can be seen that the jet pump 1 indicated by Δ in FIGS. 3 and 4 has better suction performance when it is provided below the fuel tank 2. It should be noted that the distance from the tip of the nozzle 6 to the constriction part 7a of the diffuser 8, the length L of the diffuser, and the diameter of the constriction part 7a, which were explained in the above embodiment, are only examples of settings. It is not limited.

【Effect of the invention】

As described above, the jet pump according to the invention described in claim (1) includes a nozzle that is provided at the tip of a drive pipe through which a driving fluid flows and jets out the driving fluid, and a nozzle that is concentrically located with the nozzle. a diffuser having a constriction part that throttles the injected driving fluid; a negative pressure chamber that is brought into a negative pressure state by converting the driving fluid in the diffuser from a velocity head to a pressure head; and a negative pressure chamber that is connected to the negative pressure chamber and is In a jet pump equipped with a suction pipe for sucking a driving fluid, when the diameter of the nozzle is d, the diameter D of the constriction part is D≦2d.
By setting the distance*l from the tip of the nozzle to the throttle part of the diffuser to be 2d≧2d, and the length L of the diffuser to be L≧2.5, for example, when installed above the fuel tank, can obtain the specified suction performance even when no fuel remains in the jet pump, but if it is installed at the bottom of the fuel tank, fuel will always remain in the jet pump. As a result, a paper lock phenomenon occurs as the fuel temperature rises. Therefore, when provided above the fuel tank, for example, an excellent effect can be obtained in that the best suction performance can be exhibited. Further, in the jet pump according to the invention described in claim (2), in the jet pump described in claim (1), the distance from the nozzle tip to the throttle part of the diffuser is d≦d, and the length L of the diffuser is L. With the configuration set in the above statement, for example, if the jet pump is installed on the upper side of the fuel tank, the suction performance will be low because no fuel remains in the jet pump, but the When installed on the lower side, fuel remains in the jet pump, so even if the amount of negative pressure generated in the negative pressure chamber is small, the specified suction performance can be obtained.
At this time, the paper lock phenomenon does not occur as the fuel temperature increases. Therefore, when provided below the fuel tank, an excellent effect can be obtained in that the best suction performance can be exhibited.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of an embodiment of the jet pump according to the present invention, FIG. 2 is an explanatory diagram showing a fuel piping structure using the jet pump of FIG. 1, and FIG. FIG. 4 is an explanatory diagram showing the suction performance when the jet pump is installed at the upper side of the fuel tank, and FIG. 4 is an explanatory diagram showing the suction performance when the jet pump is installed at the lower side of the fuel tank. DESCRIPTION OF SYMBOLS 1... Jet pump, 5... Drive pipe, 6... Nozzle, 7a... Throttle part, 8... Diffuser,

Claims (2)

[Claims] (1) A nozzle provided at the tip of a drive pipe through which a drive fluid flows to eject the drive fluid; a diffuser having a constriction portion concentrically with the nozzle that throttles the drive fluid injected from the nozzle; A jet pump comprising: a negative pressure chamber that becomes a negative pressure state by converting a driving fluid from a velocity head to a pressure head; and a suction pipe that connects to the negative pressure chamber and sucks the driven fluid; is d, the diameter D of the constriction part is D≦2d, the distance l from the nozzle tip to the constriction part of the diffuser is l≧2d,
A jet pump characterized in that the length L of the diffuser is set to L≧2.5L. (2) The jet pump according to claim (1), wherein the distance l from the nozzle tip to the constricted portion of the diffuser is set to l≦d, and the length L of the diffuser is set to L≧2l.