JPH07253067A - Return piping structure of fuel tank - Google Patents

Abstract

PURPOSE:To prevent generation of vapor lock in the vicinity of an injector of an engine which occurs due to high temperature fuel by providing a valve which can change over a branch pipe in the closing direction when temperature of return fuel exceeds a predetermined temperature. CONSTITUTION:A branch pipe 16 is provided in a return pipe 11 which recirculates excess fuel which do not burn in an engine, and a tip of the branch pipe 16 is connected to a pipe on the intake side of a fuel pump. A valve 17 which opens and closes both pipes 16, 11 selectively is provided in a section where the branch pipe 16 is branched from the return pipe 11, and a main gear 20 which is rotated by a spiral bimetal 22 is meshed with a follow-up gear 19 fixed on a shaft 18 of the valve 17. Consequently, when temperature of return fuel rises and reaches a predetermined temperature, the valve 17 is turned via the follow-up gear 19 due to turn of the main gear 20 due to deformation of the bimetal 22 to change the return valve 11 over into open and the branch pipe 16 over into close.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel tank return piping structure.

[0002]

2. Description of the Related Art Some fuel tanks for vehicles have a structure shown in FIGS.

In the figure, 1 is a tank body,
The filler tube 2 is connected to the side wall of the tank body 1,
A vent tube 3 that opens at the upper wall of the tank body 1 is attached to the upper portion of the filler tube 2.

Further, an evaporation tube 5 for leading the evaporated fuel in the tank body 1 to the canister 4 is provided on the upper wall of the tank body 1, and the evaporation tube 5 is provided at the opening of the evaporation tube 5 in the tank body 1. A float valve 6 is provided to prevent the outflow of fuel from the.

A discharge side pipe 7 for supplying fuel to the engine E is inserted into the tank body 1, and a fuel pump 10 having a filter 9 at the end of the suction side pipe 8 is attached to the tip thereof.

The fuel pump 10 is a return pipe 11 that recirculates surplus fuel that has not been completely burned by the engine E.
It is also located in the swirl tank 12.

Reference numeral 13 is a check valve provided on the evaporation tube 5, 14 is a strainer provided on the discharge side pipe 7, and 15 is a float gauge.

[0008]

However, in the above-mentioned conventional fuel tank, the return fuel returning from the return pipe 11 into the tank body 1 is the surplus fuel sent from the engine E, so that the fuel temperature is extremely low. Therefore, the temperature of the fuel in the tank body 1 rises due to this return fuel.

When the fuel temperature in the tank body 1 rises,
The generated amount of evaporated fuel increases, and therefore the capacity of the canister 4 must be increased accordingly, which makes it difficult to arrange other functional components in the engine room where the arrangement space is largely restricted.

In order to solve this problem, there is a case where the outlet of the return pipe is opened in close proximity to the filter on the suction side of the fuel pump (see Japanese Utility Model Laid-Open No. 3-27870). It wasn't enough to prevent a rise.

Therefore, the present invention provides a return piping structure for a fuel tank which can prevent the fuel temperature in the tank body from rising.

[0012]

[MEANS FOR SOLVING THE PROBLEMS] A fuel pump is provided in a tank body of a fuel tank, and a return pipe for returning surplus fuel from an engine is also provided, and a branch pipe is connected to the return pipe. Is connected to the intake side pipe of the fuel pump, and a valve that selectively opens and closes both passages is provided at the branch portion of the return pipe and the branch pipe, and the temperature of the return fuel is above a certain level (near the injector of the engine. At a fuel temperature at which vapor lock occurs), the drive means for switching the valve that was in the direction to close the return pipe to the direction to close the branch pipe is linked.

Further, the drive means may be composed of a main gear that rotates due to a change in temperature of the spirally wound bimetal and a slave gear that meshes with the main gear and is linked to the valve. It may be a plate-shaped bimetal, one end of which is attached to the return pipe and the other end of which is attached to the turning end of the valve, and which switches the valve according to the shape change due to temperature. It may be a solenoid.

[0014]

[Operation] Initially, the valve is switched to the direction to close the return pipe, and the high temperature return fuel is sucked from the intake pipe of the fuel pump and supplied to the engine without returning to the inside of the tank main body. The generation of evaporated fuel due to temperature rise is suppressed. However, when the temperature of the return fuel exceeds a certain level, the valve is switched to the direction of closing the branch pipe via the drive means from the viewpoint of preventing the deterioration of the operating condition rather than preventing the temperature rise of the fuel tank, and the vapor temperature is high. It prevents the fuel, which has a high content of, from being sent to the engine and causing vapor lock.

In the case where the driving means is constituted so that the main gear is rotated by the temperature change of the spirally wound bimetal and the valve is opened and closed via the slave gear,
The movement of the bimetal can be reliably transmitted to the valve.

Further, in the case where a plate-shaped bimetal is used as the driving means to open and close the valve, the structure can be simplified.

When the drive means adopts a construction in which the valve is opened and closed by using an electromagnetic solenoid, the responsiveness of the valve can be enhanced.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings by attaching the same reference numerals to the same parts as those in the conventional structure.

In the embodiment shown in FIGS. 1 to 4, the filler tube 2 is connected to the side wall of the tank body 1, and the vent tube 3 is attached to the upper portion of the filler tube 2.
An epapo tube 5 having a float valve 6 at the tip is attached to the upper wall of the tank body 1, and a discharge side pipe 7 for supplying fuel to an engine as an engine is inserted into the tank body 1, and a suction side is provided at the tip. The basic structure is the same as the above-mentioned conventional one, such as a fuel pump 10 having a filter 9 attached to the end of the pipe 8.

Here, the fuel pump 10 is located in the swirl tank 12 together with the return pipe 11 that recirculates the surplus fuel that has not been completely burned in the engine. A branch pipe 16 is branched and connected to the return pipe 11. The tip of the branch pipe 16 is connected to the suction side pipe 8 of the fuel pump 10 downstream of the filter 9 as shown in FIGS.

As shown in FIG. 1, a disc-shaped valve 1 for selectively opening and closing the return pipe 11 and the branch pipe 16 is provided at a branch portion between the branch pipe 16 and the return pipe 11.
7 is supported rotatably about a shaft 18.

As shown in FIGS. 1 and 2, a driven gear 19 (driving means) is coaxially fixed to the shaft 18 of the valve 17, and the driven gear 19 is meshed with a main gear 20 (driving means). . A shaft 21 of the main gear 20 is rotatably supported by the return pipe 11, and a bracket 23 is provided coaxially with the shaft 21 and locked to a bimetal 22 (driving means). The bimetal 22 is formed by winding in a spiral shape, and the outer end is fixed to the return pipe 11,
The inner end is locked to the engaging portion 23A of the bracket 23.

Here, the bimetal 22 rotates the inner end of the bimetal 22 when the temperature of the return fuel exceeds a certain temperature (exceeds about 70 ° C.). As a result, the rotating main gear 20 rotates the sub gear 19, that is, the valve 17 to close the end portion of the branch pipe 16 and prevent the fuel from being supplied to the engine. It is returned to the main body 1. still,
The main gear 20 and the slave gear 19 are cut at one side (the side opposite to the meshing side) around them.

According to the structure of the above embodiment, when the fuel temperature in the tank body 1 is low (about 70 ° C. or less), the bimetal 22 is not deformed, so the valve 17 is switched to the side that closes the return pipe 11. And therefore,
Excess fuel sent from the engine does not return to the swirl tank 12, but is supplied to the engine from the discharge side pipe 7 by the fuel pump 10 together with the fuel sucked from the filter 9.

Therefore, the high-temperature fuel does not return to the swirl tank 12, and the fuel temperature in the tank body 1 including the swirl tank 12 can be prevented from rising, so that the amount of vapor generated is reduced and the canister is reduced. 4 can be miniaturized.

Next, from the return pipe 11 to the swirling tank 12
When the temperature of the return fuel gradually rises and reaches a certain temperature (temperature exceeding about 70 ° C.), the bimetal 22 is deformed and the inner end of the bimetal 22 to which the bracket 23 is attached is rotated. Move the main gear 20
Thus, the secondary gear 19, that is, the valve 17 is rotated to close the branch pipe 16 (in the direction of the arrow in FIG. 1).

As a result, the high-temperature return fuel returns to the swirl tank 12, and is not supplied to the engine.
It is possible to prevent the occurrence of a situation where the vapor lock occurs near the injector of the engine and the driving performance is deteriorated.

Therefore, according to this embodiment, it is possible to prevent the fuel temperature in the tank body from increasing and to suppress the generation of a large amount of evaporated fuel, and when the temperature of the return fuel increases, It is possible to prevent the vapor lock generated in the vicinity of the injector of the engine by the return fuel having the increased vapor content and improve the operating performance of the engine.

In this embodiment, the main gear 20 and the sub gear 19 are used to change the change of the bimetal 22 by the valve 17.
Therefore, there is an advantage that the valve 17 operates reliably.

The above fuel temperature of 70 ° C. is given as an example of the temperature at which vapor lock occurs near the injector of the engine, and when the temperature at which vapor lock occurs is higher than that temperature, the temperature is the valve. 17
It becomes the switching temperature.

Next, a second embodiment of the present invention will be described with reference to FIGS.

In this embodiment, a valve 24 for selectively switching between the return pipe 11 side and the branch pipe 16 side is rotatably provided at a branch portion between the return pipe 11 and the branch pipe 16.

The valve 24 has a shaft 25 provided on one side thereof.
Is supported by the branch portion, and a locking hole 26 is provided on the other side. Then, one end of a plate-shaped and V-shaped bimetal 27 (driving means) is rotatably supported by the return pipe 11, and a hook 28 at the other end of the bimetal 27 is attached to the locking hole 26 of the valve 24. ing.

According to the structure of this embodiment, it is possible to prevent the return of the high temperature return fuel to the tank body 1 and the rise of the fuel temperature by sending the return fuel to the engine in the same manner as the above-mentioned embodiment. When the temperature of the return fuel exceeds a certain level, the shape of the bimetal 27 changes and
Valve 24 in the direction to close the branch pipe 16 as shown in FIG.
Is switched to return the fuel to the tank body 1, so that it is possible to prevent the deterioration of the driving performance due to the supply of the high-temperature return fuel to the engine.

In particular, in this embodiment, the bimetal 27 has a simple structure, and since the number of parts is small, it is easy to assemble and there is an advantage that it can be manufactured at low cost.

Next, a third embodiment of the present invention will be described with reference to FIG. In the figure, the return pipe 11 is provided with a branch pipe 16, and this branch pipe 16 is connected to the suction side pipe 8 of the fuel pump 10. A valve 30 for selectively switching between the return pipe 11 side and the branch pipe 16 side by an electromagnetic solenoid 29 as a driving means is provided at a branch portion between the return pipe 11 and the branch pipe 16.

The electromagnetic solenoid 29 normally moves the valve 30 backward (position shown in FIG. 7) and returns pipe 1.
Switch the valve 30 in the direction to close 1, and branch pipe 1
Although the return fuel is supplied to the 6 side, when the temperature of the return fuel further rises to a constant temperature and the oil temperature sensor detects this, the valve 30 is advanced by the electromagnetic solenoid 29 to move the branch pipe 16 through the branch pipe 16. When closed, the high-temperature return fuel is returned to the tank body 1.

Therefore, also in this embodiment, similarly to each of the above-described embodiments, it is possible to suppress an increase in the fuel temperature in the tank main body and prevent a large amount of evaporated fuel from being generated, and the temperature of the return fuel is constant. When the temperature rises to, the vapor lock caused by the return fuel being sent from the branch pipe 16 to the engine can be prevented, and the operating performance of the engine can be improved. It should be noted that this embodiment is also advantageous in that the responsiveness of the valve 30 is good.

[0039]

According to the invention described in claim 1, since the valve is normally switched in the direction to close the return pipe, it is possible to prevent the return fuel from flowing back into the tank main body, and the fuel in the tank main body is prevented. It is possible to prevent the temperature from rising. Therefore, it is possible to reduce the amount of vaporized fuel that is generated as the temperature of the fuel in the tank body rises, and to reduce the capacity of the canister.

Further, when the temperature of the return fuel reaches a certain temperature or higher, the valve can be switched in the direction of closing the branch pipe, so that the vapor lock in the vicinity of the injector of the engine caused by the high temperature fuel is prevented and the operation of the engine is prevented. Good performance can be maintained.

According to the invention described in claim 2, in addition to the effect of claim 1, there is an effect that the valve can be reliably opened and closed by the main gear and the slave gear.

According to the invention described in claim 3, in addition to the effect of claim 1, the structure of the driving means is simplified, so that the number of parts and the number of assembling steps are reduced, and the cost can be reduced. .

According to the invention described in claim 4, in addition to the effect of claim 1, the response of the valve can be enhanced.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a first embodiment of the present invention.

FIG. 2 is a perspective explanatory view of the same main part.

FIG. 3 is a partially enlarged view of FIG.

FIG. 4 is an overall explanatory diagram.

FIG. 5 is a sectional view of a second embodiment of the present invention, which corresponds to FIG.

FIG. 6 is a perspective view of the relevant part.

FIG. 7 is an explanatory diagram of the third embodiment of the present invention.

FIG. 8 is an explanatory diagram corresponding to FIG. 4 of the related art.

FIG. 9 is an explanatory plan view showing a fuel system of a conventional vehicle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Tank main body 8 ... Suction side pipe 10 ... Fuel pump 11 ... Return pipe 16 ... Branch pipe 17 ... Valve 19 ... Slave gear (driving means) 20 ... Main gear (driving means) 22 ... Bimetal (driving means)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location F16K 11/052 Z 31/70 A

Claims (4)

[Claims] 1. A fuel pump is provided in a tank body of a fuel tank, and a return pipe for returning surplus fuel from an engine is provided, a branch pipe is connected to the return pipe, and a tip of the branch pipe is connected to the fuel pump. A valve that is connected to the suction side pipe and selectively opens and closes both passages at the branch portion of the return pipe and the branch pipe is provided in the direction to close the return pipe when the temperature of the return fuel exceeds a certain temperature. A return pipe structure for a fuel tank, characterized in that drive means for switching the valve to a direction in which the branch pipe is closed is linked. 2. A main gear, wherein the drive means is rotated by a change in temperature of a spirally wound bimetal,
2. The fuel tank return piping structure according to claim 1, comprising a secondary gear meshing with the main gear and linked to the valve. 3. The drive means has one end attached to a return pipe and the other end attached to a rotary end of a valve,
2. The fuel tank return piping structure according to claim 1, wherein the fuel tank return piping structure is a plate-shaped bimetal that switches valves according to a change in shape due to temperature. 4. The return pipe structure for a fuel tank according to claim 1, wherein the drive means is an electromagnetic solenoid that switches a valve according to the temperature of the return fuel.