JP2002219952A - Fuel tank for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anti-corrosion fuel tank for an automobile preventing crevice corrosion in the stainless steel plate tank body. SOLUTION: In this fuel tank for the automobile formed by having the tank body 10 formed of the stainless steel plate and storing the fuel and a retainer 20 for fitting a pump feeding the stored fuel to an engine to the tank body 10, the retainer 20 is welded to the inside of the tank body 10. In this fuel tank for the automobile formed by having the tank body 10 formed of the stainless steel plate and storing the fuel and an inlet pipe 30 for feeding the fuel to the tank body 10, the inlet pipe 30 comprises a pipe part 31 letting the fuel pass through its inside and a flange part 32 formed into a flange shape in the outer circumference of the pipe part 31 and the flange part 32 is welded to the inside the tank body 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel tank for an automobile, and more particularly, to a fuel tank for an automobile having excellent corrosion resistance.

[0002]

2. Description of the Related Art In general, a container body of a fuel tank used for an automobile is formed of a carbon steel plate. Since the fuel tank contains flammable liquid fuel, it is required to have a high sealing property so that the liquid fuel inside does not leak out, and the material constituting the tank must have high corrosion resistance. Required.

In recent years, requirements for hermeticity of fuel tanks for automobiles and corrosion resistance for constituent materials of tanks have become higher, and new materials replacing conventional carbon steel sheets have been studied. Among them, stainless steel sheets are attracting attention as materials having high corrosion resistance.

An automobile fuel tank is for storing fuel. A pump for supplying the stored fuel to the engine and an inlet pipe for supplying the fuel to the container body are provided in the container body. Various accessory parts are attached.

For example, when a pump for supplying fuel to an engine is mounted on a container body, a retainer is used as a mounting member. FIG. 5 is a cross-sectional view of a conventional carbon steel plate automobile fuel tank in which a pump is attached to a container body. The retainer 20 is welded to the outside of the container body 10. Note that projection welding is used for welding because relatively quick joining is possible and the joining strength is high. Then, the mounting bracket 51 is fastened to the retainer 20 by bolts 52, and the upper mounting member 1 and the upper container member 1 constituting the container body 10.
The pump is attached by sandwiching a part of the pump between the pump and the pump.

FIG. 6 is a sectional view of a conventional carbon steel plate automobile fuel tank, in which an inlet pipe is attached to a container body. Inlet pipe 30
Consists of a pipe portion 31 through which fuel passes and a flange portion 32 formed in a flange shape on the outer periphery of the pipe portion, and the flange portion 32 is welded to the outside of the upper container member 11 constituting the container body 10. Have been. In addition, since the diameter of the inlet pipe is relatively small, so-called ring projection welding is used in which projections are formed in a ring shape on the welding surface and the ring-shaped projections are welded.

[0007]

As described above, conventionally, the container body constituting the fuel tank was formed from a carbon steel plate, but the container body was formed from a stainless steel plate which is a material having more excellent corrosion resistance. In this case, it is necessary to consider the occurrence of crevice corrosion peculiar to stainless steel.

For example, when the pump is mounted on the container body by using a retainer, the connecting portion A1 between the upper container member 11 and the retainer 20 and the mounting bracket 51 shown in FIG.
There is a possibility that a gap may be formed at a total of three places, that is, a joint A2 between the pump and the retainer 20 and a joint A3 between a part of the pump and the mounting bracket 51. In particular, when the container body 10 is formed of a stainless steel plate, the upper container member 11 and the retainer 2
When moisture or air containing moisture enters into the gap formed at the joint A1 with zero, there is a possibility that the corrosion of the gap peculiar to stainless steel occurs. Further, even when moisture is present in a joint A2 between the fitting 51 and the retainer 20 and a gap formed at a joint A3 between a part of the pump and the fitting 51, the fitting 51 and the retainer 20 are formed of stainless steel. In such a case, crevice corrosion may similarly occur. That is, if moisture exists in the gap, Cr contained in the stainless steel sheet is ionized and eluted,
The pH value of the gap decreases due to the hydrolysis reaction of ³⁺ ions. As a result, the main constituent metal of stainless steel sheet, Fe
Is promoted, leading to corrosion of the stainless steel plate in the gap.

Here, the infiltration of water into the joint A2 between the mounting bracket 51 and the retainer 20 and the joint A3 between the part of the pump and the mounting bracket 51 can be achieved by, for example, inserting packing into each joint. Can be suppressed by the method. However, since the retainer 20 is projection-welded to the outside of the container main body 10, packing cannot be inserted into the joint A1 between the upper container member 11 and the retainer 20, and water cannot enter the joint A1. It is difficult to control.

In the projection welding, projections (projections) are provided at predetermined intervals on a welding surface of a retainer, and the projections are welded to an upper container member constituting a container body. However, since it is difficult to completely crush the projection during welding, the joint surfaces of the retainer and the container member do not completely adhere to each other, and a gap is generated at a joint portion between the upper container member and the retainer. Become.

Further, as shown in FIG. 5, a mounting portion of the pump, that is, a portion surrounded by the upper container member 11, the retainer 20, the mounting bracket 51, and a part of the pump constituting the container main body 10, is provided. , Space S is made. Therefore, when moisture enters the space S from the joint A1 between the upper container member 11 and the retainer 20, the space S may become a corrosive atmosphere.

When the inlet pipe is to be attached to the container main body, the flange portion 32 is ring-projection welded to the outside of the upper container member 11 constituting the container main body 10, as shown in FIG. Therefore, only the annular projection 32a formed on the welding surface of the flange portion 32 is welded, and a gap C1 is generated between the unwelded portion of the welding surface and the upper container member 11. Since the gap C1 exists outside the container main body 10, moisture accumulates in the gap C1. When the container main body 10 is formed of a stainless steel plate, the above-described crevice corrosion unique to stainless steel may occur.

In summary, when the container body constituting the fuel tank for an automobile is formed of a stainless steel plate, a factor is a gap generated at a joint portion between the container body and the retainer and a joint portion between the container body and the inlet pipe. Become,
Crevice corrosion specific to stainless steel may occur.

As a result of intensive studies, the present inventor has found that crevice corrosion, which is a problem when a container body constituting a fuel tank for an automobile is formed of a stainless steel plate, is disposed inside the container body. We got the knowledge that it can be suppressed by bringing it.

The present invention has been made on the basis of the findings, and it is an object of the present invention to provide a fuel tank for an automobile which prevents crevice corrosion in a container body made of stainless steel plate and is more resistant to corrosion.

[0016]

(1) A fuel tank for an automobile according to the present invention is formed of a stainless steel plate and has a container body for storing fuel and a pump for supplying the stored fuel to an engine mounted on the container body. An automotive fuel tank comprising: a retainer, wherein the retainer comprises:
It is characterized by being welded to the inside of the container body (corresponding to claim 1).

That is, the vehicle fuel tank of the present invention
The container body that constitutes the fuel tank is made of stainless steel plate, and the retainer for attaching the attached pump to the container body is welded to the inside of the container body, thereby suppressing the occurrence of crevice corrosion unique to stainless steel. It is a highly durable fuel tank.

First, the mechanism of crevice corrosion will be described. Usually, on a stainless steel surface in a water environment, a very small amount of metal (Cr, which is a main alloy constituting stainless steel) is eluted through a passive film (anode reaction). Since the elution of Cr is an electrochemical reaction, a cathodic reaction commensurate with this is necessary, and a reduction reaction of dissolved oxygen occurs in a neutral aqueous solution. The reduction reaction of dissolved oxygen initially proceeds similarly inside and outside the gap,
Replenishment of dissolved oxygen is restricted inside the gap where mass transfer through the narrow inlet is restricted, and oxygen inside the gap is immediately consumed. Therefore, Cr elutes exclusively from the stainless steel inside the gap.

On the other hand, with respect to Cr ³⁺ ions eluted by the anodic reaction in the gap, Cl ⁻ ions existing in the environment flow (migration) in order to satisfy the liquidity and electrical neutrality conditions in the gap. As a result, the Cl ^- ion concentration inside the gap increases. Further, since the mass transfer through the entrance of the gap is restricted, the eluted Cr ³⁺ ions accumulate inside the gap, cause a hydrolysis reaction to release H ⁺ ions, and the pH value of the liquid inside the gap is increased. Lower. Thus, high Cl
^- the liquid condition that ion concentrations and low pH values are achieved, the ionization of Fe which is the main constituent metal of the stainless steel is accelerated corrosion of the stainless steel progresses by Fe is eluted.

As described above, the fuel tank for an automobile according to the present invention includes a retainer for mounting the pump on the container body.
It is welded inside the container body. The method of welding the retainer is not particularly limited.Especially, in the case of welding in which the joint surfaces of the retainer and the container body do not completely adhere to each other, such as projection welding, crevice corrosion should be effectively suppressed. Can be.

That is, by welding the retainer to the inside of the container body, there is no water present at the joint between the stainless steel plate and the retainer that form the container body where crevice corrosion is expected to occur. The occurrence of crevice corrosion can be suppressed.

(2) When the retainer is mounted inside the container main body, the manner in which the pump is mounted on the container main body is not particularly limited. However, as one desirable embodiment, the container main body has an opening through which the pump is inserted. The retainer has a female screw formed on a surface to be welded, and is welded around the opening, and a mounting bracket is fastened to the retainer through a stainless steel plate forming the container body, and the mounting is performed. A part of the pump is sandwiched between the metal fitting and the outer surface of the stainless steel plate around the opening, so that the pump can be mounted (corresponding to claim 2).

When this embodiment is adopted, the pump can be easily and firmly attached to the container main body by using the retainer, and in addition, the moisture to the joint between the stainless steel plate forming the container main body and the retainer can be obtained. And the penetration of moisture into the space created in the mounting portion of the pump from the joint portion can be prevented, so that the occurrence of crevice corrosion is suppressed, and a more durable fuel tank is obtained.

(3) Further, another fuel tank for an automobile according to the present invention is formed of a stainless steel plate and stores a fuel in a container main body, and is inserted into an opening formed in the container main body to store the fuel. An automotive fuel tank comprising an inlet pipe for supplying to a container body, wherein the inlet pipe has a pipe portion through which fuel passes and a flange formed in a flange shape on an outer periphery of the pipe portion. And the pipe portion is inserted into the opening, and the flange portion is welded to the inside of the container body (corresponding to claim 3).

That is, in the fuel tank for an automobile, the container body constituting the fuel tank is formed from a stainless steel plate, and an inlet pipe as an accessory is attached from the inside of the container body. By welding the inlet pipe to the inside of the container main body, a gap generated at the joint between the container main body and the inlet pipe, which is expected to be the most severely crevice corrosion, exists inside the container main body, so the gap Infiltration of moisture into the stainless steel plate can be prevented, and occurrence of crevice corrosion of the stainless steel plate can be suppressed.

(4) When the inlet pipe is welded to the inside of the container body, a gap may be formed at a position where the outer peripheral surface of the pipe portion of the inlet pipe and the opening of the container body are close to each other. In this case, it is desirable to seal the portion where the outer peripheral surface of the pipe portion of the inlet pipe is close to the opening of the container body (corresponding to claim 4). By performing the sealing, even if a gap is formed in the above-mentioned portion, since the ingress of moisture from the gap is suppressed, the occurrence of crevice corrosion is suppressed, and a more durable automotive fuel. It becomes a tank.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, as one embodiment of a vehicle fuel tank of the present invention, an outline of a vehicle fuel tank having a retainer and an inlet pipe will be described, and thereafter, a vehicle fuel tank of the present invention will be described. An embodiment of each joint portion of the retainer and the inlet pipe in the above will be described in detail.

FIG. 1 schematically shows an automotive fuel tank to which a retainer and an inlet pipe are joined. The fuel tank 1 for an automobile is formed of a stainless steel plate, and has a container body 10 for storing fuel, a retainer 20 for attaching a pump for supplying the stored fuel to the engine to the container body 10, and is provided in the container body 10. An inlet pipe 3 inserted into the opening for supplying fuel to the container body 10
0. The container body 10 includes the upper container member 1
1 and a lower container member 12, and the upper container member 1
The lower container member 1 and the lower container member 12 are joined by flanges 11a and 12a formed at the openings of both members.
The retainer 20 and the inlet pipe 30 are welded from the inside of the container body 10, that is, from the inside of the upper container member 11 constituting the container body 10. Incidentally, the upper container member 11 and the lower container member 12 connect the retainer 20 and the inlet pipe 30 to the upper container member 11.
It is joined after welding inside.

In the fuel tank for an automobile, both the joint portion between the retainer and the container body and the joint portion between the inlet pipe and the container body, which are expected to cause crevice corrosion peculiar to stainless steel, are brought inside the container body. This prevents moisture from penetrating into both joint portions, and can more effectively suppress crevice corrosion, so that the automobile fuel tank is extremely resistant to corrosion.

The vehicle fuel tank in the present embodiment is merely an example, and the vehicle fuel tank of the present invention is not limited to the above embodiment.
For example, the present invention can also be implemented in a mode that does not include a retainer or an inlet pipe. Only one of them may be carried out inside the container body.

(1) Embodiment of Retainer Joint Section FIG. 2 is a sectional view of an embodiment of an automobile fuel tank according to the present invention, in which a pump is mounted on a container body. The container main body 10 has an opening into which the pump 40 is inserted, and the retainer 20 has a female screw 53 formed on the surface to be welded.
0, ie, inside the upper container member 11 constituting the container body 10 by projection welding. A mounting bracket 51 is fastened to the retainer 20 by bolts 52 over the upper container member 11 which is a stainless steel plate forming the container body 10. That is, the mounting bracket 5
1. A hole is formed in the upper container member 11 at a position corresponding to the female screw 53 formed in the retainer 20, and the bolt 52 passes through the hole of the mounting bracket 51 and the upper container member 11 to the retainer 20. It is screwed into the formed female screw 53. The pump 40 is inserted into the opening of the container body 10, and is partially attached between the mounting bracket 51 and the outer surface of the container member 11, which is a stainless steel plate around the opening, so that the pump 40 is attached to the container body 10. ing.

The container body 1 in which crevice corrosion is expected to occur
Since the joint A1 between the upper container member 11 and the retainer 20, which constitutes the container 0, is located inside the container body 10, no water permeates into the joint. Therefore, crevice corrosion at the joint between the container body and the retainer is suppressed.

Further, the mounting portion of the pump, that is, the upper container member 11 constituting the container main body 10, the mounting bracket 5
A space S is formed in a portion surrounded by 1 and a part of the pump. However, the joint A between the mounting bracket 51 and a part of the pump, which is expected as a water infiltration route, is used.
3, and since the packing is sandwiched at the joint A4 between the mounting bracket 51 and the upper container member 11, the intrusion of moisture from both joints can be suppressed.

The above-described embodiment in which the retainer is joined is merely an example, and the vehicle fuel tank of the present invention is not limited to the above-described embodiment. The vehicle fuel tank of the present invention can be implemented in various forms including various modifications and improvements based on the knowledge of those skilled in the art, including the above embodiment.

For example, the automobile fuel tank of the present invention of the above embodiment uses projection welding as a method for welding the retainer to the inside of the container body. However, the method for welding the retainer of the automotive fuel tank of the present invention is not particularly limited. For example, spot welding, laser welding, arc welding, or the like can be used.
In addition, resistance welding such as projection welding and spot welding is preferably used for welding relatively thin plates, and since the heat input during welding is small and relatively quick joining is possible,
When the mode of welding by resistance welding is employed, deformation of the stainless steel plate container body due to heat generated at the time of welding can be prevented, and an automobile fuel tank having a high joining strength of the retainer can be obtained.

The fuel tank for an automobile of the present invention does not particularly limit the type of stainless steel sheet forming the container body.
An austenitic stainless steel plate or the like may be used. In particular, an embodiment in which the container body is formed using a ferritic stainless steel sheet is desirable because it is inexpensive and easy to process as compared with austenitic stainless steel. As ferritic stainless steel, for example, SUS436 (JIS
G4305), SUS409 (JIS G4312)
Etc. can be used. The automotive fuel tank of this embodiment, in which the container body is formed of ferritic stainless steel, is an inexpensive and more durable fuel tank.

Further, the material of the retainer of the automotive fuel tank of the present invention is not particularly limited, and the retainer can be formed from various materials such as carbon steel and stainless steel.

In the fuel tank for an automobile according to the present invention of the above-described embodiment, packing is sandwiched at a joint between a part of the pump and the mounting bracket and the upper container member, or at a joint between the mounting bracket and the upper container member. However, as long as the airtightness can be sufficiently maintained at each joint, the embodiment can be carried out without using packing.

(2) Embodiment of the Inlet Pipe Joining Section (a) FIG. 3 is a sectional view of an embodiment of an automobile fuel tank according to the present invention, in which an inlet pipe is attached to a container body. . The inlet pipe 30 includes a pipe portion 31 through which fuel passes, and a flange portion 32 formed in a flange shape on the outer periphery of the pipe portion 31. The pipe portion 31 is inserted through an opening formed in the container body 10. The flange portion 32 is welded to the inside of the container body 10, that is, to the inside of the upper container member 11 constituting the container body 10. For the welding, ring projection welding is used in which an annular projection 32a is formed on the welding surface of the flange portion 32 and the annular projection 32a is welded.

Of the welding surface of the flange portion 32, only the annular projection 32a is the upper container member 1 constituting the container body 10.
As a result, a gap C1 is formed between the unwelded portion of the welding surface and the upper container member 11. However, in the present embodiment, since the gap C1 is inside the container main body 10, moisture does not accumulate in the gap C1 and the occurrence of crevice corrosion can be suppressed.

(B) FIG. 4 is a cross-sectional view of an embodiment in which the sealing is provided at a position where the outer peripheral surface of the pipe portion of the inlet pipe and the opening of the container main body are close to each other, and where the inlet pipe is attached to the container main body. Show.

As shown in FIG. 3, the inlet pipe 30 includes a pipe portion 31 and a flange portion 32 formed in a flange shape on the outer periphery of the pipe portion 31.
1 is inserted through an opening formed in the container body 10, and the flange portion 32 is joined to the inside of the container body 10, that is, the inside of the upper container member 11 constituting the container body 10 by ring projection welding. In this embodiment, a gap C2 is formed at a position where the outer peripheral surface of the pipe portion 31 and the opening of the container body are close to each other.
Sealing is provided by filling with paraffin.

As described above, of the welding surface of the flange portion 32, only the annular projection 32a is welded to the upper container member 11 constituting the container body 10, so that the non-welded portion of the welding surface and the upper container member 11 And a gap C1 is generated between them. However, in the present embodiment, the gap C1 is
Since it is inside 0, moisture does not accumulate in the gap C1 and the occurrence of crevice corrosion can be suppressed. further,
Since the infiltration of moisture from the gap C2 is also suppressed, the automotive fuel tank employing this embodiment is a fuel tank that is more resistant to corrosion.

The above two embodiments of the joint portion of the inlet pipe are merely examples, and the automobile fuel tank of the present invention is not limited to the above embodiment. The vehicle fuel tank of the present invention can be implemented in various forms including various modifications and improvements based on the knowledge of those skilled in the art, including the above embodiment.

For example, the fuel tank for an automobile according to the present invention of the above embodiment uses ring projection welding as a method for welding the inlet pipe to the inside of the container body. However, the automotive fuel tank of the present invention does not particularly limit the welding method of the inlet pipe,
For example, spot welding, seam welding, laser welding, or the like can be used. Note that, similarly to the case of the retainer, resistance welding such as projection welding or spot welding is used favorably for welding relatively thin plates, and since the heat input during welding is small and relatively quick joining is possible, When the mode of welding by these resistance welding is adopted, the deformation of the container body made of stainless steel plate due to the heat generated at the time of welding can be prevented, and the fuel tank for the automobile having a high joining strength of the inlet pipe is obtained. .

The automotive fuel tank of the present invention of the above embodiment is sealed using paraffin because of its low melting point and excellent filling properties. And styrene-butadiene rubber. In addition, the method of sealing is not particularly limited, and the sealing can be carried out by filling the sealing agent, packing the packing, or the like. In addition, when considering easy and low cost, it is preferable to perform the sealing by filling.

Further, in the fuel tank for an automobile of the present invention, the material of the inlet pipe is not particularly limited. For example, the inlet pipe can be formed from various materials such as carbon steel and stainless steel.

[0048]

According to the present invention, the container body constituting the fuel tank for an automobile is formed of a stainless steel plate, and the joint between the container body and the retainer or the inlet pipe is placed inside the container body.

The fuel tank for an automobile according to the present invention having such a configuration can significantly suppress crevice corrosion in a container body made of a stainless steel plate, and is a fuel tank for an automobile having high corrosion resistance.

[Brief description of the drawings]

FIG. 1 is an embodiment of the present invention, and schematically shows an automotive fuel tank to which a retainer and an inlet pipe are joined.

FIG. 2 is a sectional view of an embodiment of a fuel tank for a vehicle according to the present invention, showing a mounting portion of a pump in a container body.

FIG. 3 is a sectional view of an embodiment of an automotive fuel tank according to the present invention, showing a mounting portion of an inlet pipe in a container body.

FIG. 4 is a cross-sectional view of a mounting portion of an inlet pipe in a container main body, which is a mode in which a sealing which is one embodiment of an automobile fuel tank of the present invention is performed.

FIG. 5 is a cross-sectional view of a conventional carbon steel plate automobile fuel tank, showing a mounting portion of a pump in a container body.

FIG. 6 is a cross-sectional view of a conventional carbon steel plate fuel tank for an automobile, showing a mounting portion of an inlet pipe in a container body.

[Explanation of symbols]

 1: Fuel tank for automobile 10: Container body 11: Upper container member 12: Lower container member 11a, 12a: Flange 20: Retainer 30: Inlet pipe 31: Pipe portion 32: Flange portion 32a: Annular protrusion 40: Pump 51: Mounting bracket 52: Bolt 53: Female thread A1: A junction between upper container member and retainer A2: A junction between mounting bracket and retainer A3: A junction between a part of pump and mounting bracket A4: Mounting bracket and upper container member C1, C2: Clearance S: Space

Claims (4)

[Claims] 1. An automobile fuel tank comprising: a container body formed of a stainless steel plate for storing fuel; and a retainer for attaching a pump for supplying the stored fuel to an engine to the container body, The fuel tank for an automobile, wherein the retainer is welded to an inside of the container body. 2. The container body has an opening into which the pump is inserted, and the retainer has a female screw formed on a surface to be welded, and is welded around the opening. A mounting bracket is fastened to the retainer over the stainless steel plate forming the container body, and a part of the pump is sandwiched between the mounting bracket and the outer surface of the stainless steel plate around the opening, so that the pump is mounted. An automotive fuel tank according to claim 1, wherein 3. A container main body formed of a stainless steel plate and storing fuel, and an inlet pipe inserted into an opening formed in the container main body and supplying fuel to the container main body. A fuel tank for an automobile, wherein the inlet pipe includes a pipe part through which fuel passes and a flange part formed in a flange shape on an outer periphery of the pipe part, and the pipe part is inserted through the opening. An automotive fuel tank in which the flange is welded to the inside of the container body. 4. The fuel tank for an automobile according to claim 3, wherein a seal is provided at a position where an outer peripheral surface of a pipe portion of the inlet pipe is close to an opening of the container body.