JP6285706B2 - Automotive fuel tank - Google Patents

Description

  The present invention relates to a metal automobile fuel tank having an outer surface coated with a coating film excellent in chipping resistance, which transmits operating noise and vibration of an electric pump built in the fuel tank, in particular, idling stop. The present invention relates to a fuel tank for an automobile that reduces the transmission noise and vibration of an electric pump to the outside.

  2. Description of the Related Art In recent years, an automobile having an idling stop function (stops an engine when stopped or at a very low speed and starts the engine again when starting or running) for the purpose of reducing the fuel consumption of the automobile due to atmospheric environment regulations. It has been realized.

  Under such circumstances, the problem with the idling stop function is how to restart the stopped engine smoothly in a short time, and various measures for restarting have been studied and some of them have been put into practical use. Has been. For example, it is known that the operation of the electric pump is maintained even at idling stop (engine stop) so that the pressure in the fuel pipe is kept constant so that the engine can be restarted as smoothly as possible. (Patent Document 1).

JP 2010-19088 A (paragraphs [0024], [0040], [0041]) JP 2007-91149 A

  However, in the technique of operating the electric pump at the time of idling stop as in Patent Document 1, when this electric pump is disposed in the fuel tank, there is a problem that affects riding comfort (comfort in the vehicle).

  In other words, the noise at the time of engine operation (driving) propagating from the engine room to the inside of the automobile vehicle is eliminated, but since the electric pump built in the fuel tank is operating, this operation noise and operation Vibrations are heard in the car as an irritating sound along the fuel tank housing. In particular, in this state, that is, when idling is stopped, the engine sound is not generated at all and the interior of the vehicle is quiet. Therefore, the above operating sound can be heard remarkably and give an unpleasant feeling as an unpleasant sound. It turned out to be.

  Therefore, the present inventors investigated and analyzed the operating sound and the operating vibration of the electric pump in order to know the phenomenon in detail. As a result, vibration due to the operation of the electric pump in the fuel tank resonates in the fuel tank main body and the space inside the fuel tank, and the resonated vibration travels from the housing (tank wall) of the fuel tank through the vehicle body to the interior of the automobile. It turned out that it became NVH (Noise Vibration Harshness) propagating to space.

  This is more noticeable for metal fuel tanks based on metal sheets than for resin fuel tanks based on high-density polyethylene resin, and the outer surface of the metal tank is covered. It was found that the quality of the paint was also affected. It was also found that these pump operating noises and operating vibrations tend to be transmitted through a metal fuel tank and a vehicle body on which it is mounted in a specific frequency band. At the same time, the amount of fuel oil in the fuel tank (total weight of the fuel tank) is also affected, so that the fuel oil is near the point F (Full: Abbreviation for full, indicating that the fuel in the fuel tank is full). It has also been found that it becomes more prominent near the point E (Empty: an abbreviation for empty, indicating that the fuel oil in the fuel tank is below a predetermined level).

  Therefore, the present inventors have further studied on countermeasures in order to reduce the noise in the specific frequency band, and in the research, the inventors cannot cope with it by devising a coating film that covers the casing of the fuel tank. I deepened my research from this point of view.

  In general, in an automobile fuel tank, it is known to coat the outer surface of a metal fuel tank housing for corrosion resistance, chipping resistance, and the like. For example, Patent Document 2 discloses applying a mixed paint composed of an acrylic resin and a melamine resin for corrosion resistance and the like. It is also well known to form a vinyl chloride coating to ensure chipping resistance. However, the conventional coating film only forms a coating film from the performance generally required for fuel tanks such as corrosion resistance and chipping resistance. There was no literature that was considered at all.

  As a result, the researchers have studied their own research, and as a result, when a specific coating is applied, the original performance of the chipping-resistant coating coated on the outer surface as a coating on the fuel tank is maintained. However, the present invention has been achieved that can reduce noise in the specific frequency band.

Specifically, according to the first aspect of the present invention, an electric pump for supplying fuel to the engine is provided in a fuel tank made of a casing formed of a metal-based sheet material, and the engine in the fuel tank is stopped when idling is stopped. In an automotive fuel tank in which an electric pump is operating, an outer surface of the housing is coated with a chipping-resistant coating film, and the chipping-resistant coating film is made of 10 to 30% by mass of vinyl chloride resin or In the range of 10 to 30% by mass of acrylic resin, the total value of the vinyl chloride resin or the acrylic resin alone or mixed is 10 to 30% by mass as a base material. mica powder to reduce the transmission to the outside of the operating noise of the frequency band of 100Hz~200Hz of the electric pump during stop, is mixed in the range of 7.5 to 15.0 wt% And wherein the are.

A second aspect of the present invention is that, in the first aspect, the chipping-resistant coating film is 15 to 40% by mass of a plasticizer, 0 to 50% by mass of calcium carbonate, and 0. 1 to 15% by mass, 1 to 15% by mass of rust preventive pigment, 0.1 to 1.0% by mass of color pigment, 0.1 to 5% by mass of stabilizer, and 1 to 5% by mass of lightweight aggregate It is characterized by that.

The invention of claim 3 is characterized in that, in claim 1 or 2, the mica powder has an aspect ratio of 50 (50: 1) or more and a particle diameter (length) of 10 to 200 μm .

According to a fourth aspect of the present invention, in any one of the first to third aspects, the film thickness of the anti-chipping coating film is 300 to 2000 μm.

  According to the first aspect of the present invention, the coating film for covering the casing made of a metal sheet material (steel) by pressing or the like satisfies the performance such as chipping resistance and corrosion resistance, and the casing of the fuel tank. Since the noise of the electric pump transmitted through the (tank wall) is reduced, unpleasant noise at the time of idling stop can be reduced, the ride comfort can be improved, and comfort can be obtained.

Furthermore, when the coating film is formed by mixing mica powder on a base material composed of vinyl chloride resin or acrylic resin alone or mixed, the coating film of the fuel tank for automobiles has performance such as chipping resistance and corrosion resistance. It has enough.

Further, when mica is mixed in the range of 3.0 to 15.0% by mass, particularly in the range of 7.5 to 15.0% by mass , the performance as the fuel tank and at the time of idling stop The noise reduction can be effectively demonstrated in a balanced manner.

Further, the chipping-resistant coating film is in the range of 10-30% by mass of vinyl chloride resin or 10-30% by mass of acrylic resin, and the total value of vinyl chloride resin or acrylic resin alone or mixed is 10-30% by mass. As a result , the performance as the fuel tank and the noise reduction at the time of idling stop can be balanced and more effectively exhibited.

  According to invention of Claim 4, since the film thickness of the coating film for chipping-proof is 300-2000 micrometers, the performance as the above-mentioned fuel tank and vibration damping nature can fully be exhibited.

It is a graph which shows the relationship between a film thickness and a loss coefficient. It is a graph which shows the measured value of a room sound pressure level.

  Hereinafter, embodiments of the present invention will be described in detail. The following description of the preferred embodiment is merely exemplary in nature.

  In the embodiment of the present invention, although not shown in the drawings, an electric pump for supplying the fuel to the engine is built in the automobile fuel tank, and the outer surface of the housing of the fuel tank made of metal sheet material (steel) Are coated with a chipping-resistant coating film, and the chipping-resistant coating film contains mica. As a result, when idling is stopped, the electric pump built in the fuel tank is operating, but the operating noise at that time and unpleasant noise (including vibration) at a specific frequency due to the operating vibration are reduced.

  In addition, the electric pump operating noise and the operating vibration include the vibration component generated when the impeller installed in the pump is rotated by the electric motor and the pump pump when fuel pumped from the pump is not sent to the engine side. There are vibrations associated with the discharge of fuel discharged (from a relief valve or the like) to avoid an increase in pressure.

  Hereinafter, in the embodiment of the present invention, the operation sound and the operation vibration that are operating in the fuel tank when idling is stopped are referred to as the operation sound of the electric pump. In the present invention, the electric pump is a pump provided in the fuel tank for supplying the fuel in the fuel tank, and can be operated regardless of the operation (operation) of the engine. , “In-tank electric fuel pump”, “electric fuel pump”, and “electromagnetic pump” are also included.

  The fuel tank casing of the present invention can use various steel plates made of metal sheet material, but is made of Nippon Steel & Sumitomo Metal Co., Ltd., which is excellent in rust prevention performance on the plated steel plate, particularly on the inner and outer surfaces. “ECOCOAT (registered trademark) -S” steel sheet (hot tin galvanized steel sheet) is preferred.

  The chipping-resistant coating film is preferably a base material made of a vinyl chloride resin or an acrylic resin, and is preferably formed by dispersing and mixing mica into this base material, and may contain other additives.

  As the mica, natural mica or synthetic mica can be used.

  The fuel tank manufacturing method of the present invention is a method of press-molding the above steel plate and assembling the tank accessory parts by welding or the like to form an upper structure and a lower structure of the fuel tank. After being layered and joined by seam welding, etc., and made into a tank shape, it is manufactured by coating a paint prepared from the coating film composition of the present invention through a degreasing and washing process that is a general pretreatment for coating. The The production of the fuel tank including the press working, joining, molding and the like is performed by a conventionally known method. At this time, the shape and size of the fuel tank are not particularly limited. Furthermore, the method of coating and forming the coating film is carried out by a known method such as spray coating, powder coating, dip coating, curtain flow, or cationic electrodeposition coating. Further, a chemical conversion treatment step such as zinc phosphate treatment may be performed in a general pretreatment for coating.

  The thickness of the coating film is not particularly limited, but is determined according to the target function. If the coating film is too thin, chipping resistance and unpleasant noise reduction performance at a specific frequency are insufficient, and if the coating film is too thick, the cost increases and the weight increases. Therefore, the average thickness is preferably 300 to 2000 μm, particularly 600 to 1500 μm. The drying conditions are not particularly limited, but it is preferable to bake and harden in an atmosphere of 100 to 200 ° C. for about 10 to 30 minutes.

  Next, each component will be described.

(Vinyl chloride resin (PVC))
For the purpose of improving the physical properties of the dry paint film of the paint, it is preferable that the total resin component of the paint is mixed in a proportion of 10 to 30% by weight, particularly 15 to 25% by weight. The above is preferable. If it is less than 10% by mass, the mechanical properties (strength) of the dried coating film will be insufficient and chipping resistance will be reduced. If it is more than 30% by mass, the Tg value (glass transition point) of the coating film will be reduced. Since it shifts to a low temperature side, the vibration damping property at normal temperature is lowered and the storage stability of the composition is lowered and the viscosity tends to be increased.

(acrylic resin)
For the purpose of improving the physical properties and the frequency characteristics of the dry paint film of the paint, the acrylic resin is preferably mixed at a ratio of 10 to 30% by mass with respect to the paint, especially the total resin component of the paint. It is preferable to set it to -25 mass% or more. When the amount is less than 10% by mass, the Tg value of the coating film shifts to a low temperature side, the vibration damping property at room temperature decreases, and the adhesion of the coating film deteriorates. When the amount exceeds 30% by mass, storage stability is obtained. The coating workability deteriorates because the viscosity tends to decrease and the viscosity increases, so the above range is preferable.

(Combination of vinyl chloride resin and acrylic resin)
In addition, it is preferable that there exists at least one resin of a vinyl chloride resin and an acrylic resin as a base material of the coating film for chipping resistance. In particular, the inclusion of both is preferable from the viewpoint of chipping resistance and vibration damping properties. If the amount is too small, the effect is weak. If the amount is too large, the cost increases and the productivity deteriorates. Or it is preferable that the mixed total value is 10-30 mass%.

(Adhesion imparting agent)
The adhesion-imparting agent is preferably mixed at a ratio of 0.1 to 15% by mass with respect to the whole paint for the purpose of improving adhesion to a metal material that is an object to be coated. If it is less than 0.1% by mass, the polar molecules of the adhesion-imparting material will hardly work and the adhesion will be reduced. If the amount is more than 15% by mass, the coating workability deteriorates because the storage stability tends to decrease and the viscosity tends to increase. As the adhesion-imparting agent, known materials can be used.

(mica)
Mica is capable of reducing noise at a specific frequency, and is preferably mixed at a ratio of 3 to 15% by mass, particularly 7.5 to 10.5% by mass with respect to the entire coating material. When it is less than 3% by mass, the vibration damping effect of the coating film is lowered. If it is more than 15% by mass, the vibration damping property is improved, but the viscosity of the coating tends to increase, so that the coating workability is deteriorated. Considering the vibration damping performance and workability, the aspect ratio is preferably 50 (50: 1) or more and the particle diameter (length) is preferably 10 to 200 μm.

  As the mica of the present invention, natural mica, phlogopite and muscovite, synthetic mica, fluorine phlogopite, and tetrasilicon mica are particularly effective for improving damping properties.

(Anti-rust pigment)
The rust preventive pigment is mixed for the purpose of improving the rust preventive performance of the metal substrate constituting the tank wall, and is preferably mixed at a ratio of 1 to 15% by mass with respect to the entire paint. When the amount is less than 1% by mass, the amount of passive film formed decreases, and the rust prevention effect decreases. If it is more than 15% by mass, the coating workability tends to deteriorate because the viscosity of the coating tends to increase. The rust preventive pigment is not particularly limited and may be a known one. For example, zinc phosphate, iron phosphate, aluminum phosphate, calcium phosphate, zinc phosphite, zinc cyanide, zinc oxide, aluminum tripolyphosphate , Zinc molybdate, aluminum molybdate, calcium molybdate, aluminum phosphomolybdate, bismuth hydroxide, bismuth oxide, bismuth lactate, bismuth nitrate, etc., phosphoric acid systems such as phosphoric acid, tripolyphosphoric acid, phosphomolybdic acid An inorganic phosphoric acid type rust preventive pigment such as phosphorous acid type is preferred.

  Note that a curing catalyst of a metal compound such as zinc, tin, bismuth, copper, manganese, and cobalt may also be used as a rust preventive pigment dispersed together with a pigment dispersing resin.

  Other pigments include, for example, colored pigments such as titanium oxide, carbon black, black iron oxide, copper chrome black, copper iron manganese black and bengara, kaolin, talc, aluminum silicate, calcium carbonate, mica, clay and silica. An extender pigment such as can be used.

(Color pigment)
Colored pigments such as carbon black are mixed for the purpose of improving the weather resistance of the coating film (discoloration or deterioration due to ultraviolet rays, ozone, etc.). It is preferable to mix in the ratio of 0.0 mass%. When it is less than 0.1% by mass, the color tone is lowered and the weather resistance is also lowered. If the amount is more than 1.0% by mass, the coating properties are deteriorated because the mechanical properties deteriorate and the viscosity tends to increase at the same time. A well-known thing can be employ | adopted as a coloring pigment. (Stabilizer)
Stabilizers prevent the molecular structure from becoming unstable due to the dehydrochlorination reaction of vinyl chloride resin components in high-temperature environments such as baking and drying of paints and chlorides that are secondary generated after painting. Is formed stably. Known stabilizers can be used as the stabilizer.

  Further, it is mixed for the purpose of improving the durability of the coating film while maintaining the hygroscopic foamability of the resin and improving the chipping resistance. Therefore, it is preferable to mix in the ratio of 0.1-5 mass% with respect to the whole coating material. When the amount is less than 0.1% by mass, the effect of suppressing the dehydrochlorination reaction is lowered, and at the same time, the hygroscopic foam resistance is also lowered. If it is more than 5% by mass, the coating workability tends to deteriorate because the viscosity of the coating tends to increase. What is necessary is just to employ | adopt a well-known stabilizer.

(Plasticizer)
The plasticizer is mixed for the purpose of controlling the plasticization of thermoplastic resin components such as vinyl chloride resin to form a stable coating film. It is preferable to mix in the ratio of 15-40 mass% with respect to the whole coating material. If it is less than 15% by mass, the plasticization becomes difficult to control and the storage stability tends to decrease and the viscosity tends to increase, so the coating workability deteriorates. When it is more than 40% by mass, the Tg value of the dried coating film is shifted to the low temperature side and the vibration damping property is lowered. What is necessary is just to employ | adopt a well-known thing as a plasticizer.

(Lightweight bone agent)
Light weight aggregates such as plastic baluns are preferably mixed at a ratio of 1 to 5% by mass with respect to the whole paint for the purpose of reducing the weight of the paint. When the amount is less than 1% by mass, the effect of reducing the weight of the paint is small and the coating weight after drying tends to increase. When it is more than 5% by mass, the ratio of the resin component is lowered, the mechanical properties (strength) of the dried coating film are insufficient, and the chipping resistance is lowered. What is necessary is just to employ | adopt a well-known thing as a lightweight aggregate.

(Calcium carbonate)
Calcium carbonate, such as heavy calcium carbonate and surface-treated calcium carbonate, contributes to the viscosity characteristics (thixotropy), mechanical characteristics, and adhesion of paints, and at the same time has a greater price-reducing effect than resin components and pigments. It is a paint adjusting agent mixed for the purpose of adjusting various performances. It is preferable to mix in the ratio of 0-50 mass% with respect to the whole coating material, and it is especially preferable to set it as 2.0-16.5 mass% with respect to the whole coating material.

  Other additives may include a commercially available adhesion-imparting agent such as a polyester resin, an antifoaming agent, a dispersant, a leveling agent, and the like, but these are not particularly limited.

Hereinafter, the present invention will be specifically described with reference to Examples. As a material for the housing of the fuel tank, a test piece 1 obtained by cutting a 0.8 mm thick tin-galvanized steel sheet (adhesion amount per side of 30 g / m ² ) into a length of 150 mm and a width of 100 mm, and a length of 230 mm and a width of 15 mm Two types of test pieces 2 were prepared.

(Examples 1 to 9, Comparative Examples 1 and 2)
The composition components of the coating films of Examples 1 to 9 and Comparative Examples 1 and 2 were applied to the surfaces of the test piece 1 and the test piece 2. Specifically, the surface of the test piece is coated with an airless coating machine (GRACO Co., Ltd. airless gun, coating dynamic pressure 5.0 MPa, gun distance 300 mm, nozzle type 631) so that the film thickness is 300 μm. did. Thereafter, the steel sheet was heated and held at 140 ° C. for 20 minutes to bake and harden the coating film.

  In addition, the composition component of each coating film of Examples 1-9 and Comparative Examples 1 and 2 is shown in Table 1.

  And about the test piece 2, the test piece of the film thickness of 600 micrometers and 2000 micrometers was also produced similarly to each test piece of the film thickness of 300 micrometers.

  For these test pieces 2 having a plurality of film thicknesses, the number loss coefficient (η) for each film thickness is measured by the half-width method at the secondary resonance point using a cantilever method loss factor measuring machine (manufactured by Bruel & Care). ) Was measured and evaluated (measurement temperature 20 ° C.).

  The result of this experiment is shown in FIG. The points that can be understood from this experiment are that in Examples 1 to 9, the loss factor (vibration suppression) is greatly improved by increasing the film thickness of the coating film, but in Comparative Examples 1 and 2, the film thickness is large. Even so, the loss factor is almost unchanged. Therefore, it can be judged that it is effective to add mica from the viewpoint of vibration control. In particular, it can be seen that increasing the amount of mica to be added tends to dramatically improve the vibration damping performance.

  In response to this result, next, when mica was added, a comparative experiment was further conducted on the chipping resistance function, corrosion resistance, and the like that the casing of the fuel tank should originally have.

  In this comparative experiment, Examples 1 to 7 and Comparative Example 1 were performed. The amount of mica in Examples 8 and 9 is the same as that in Example 1. In Comparative Example 2, the amount of mica is zero as in Comparative Example 1. Therefore, the function of the coating film by the amount of mica can be predicted. I omitted it.

  Next, details of this comparative experiment will be described.

(A: Paintability)
The paintability was evaluated by the pattern width formed on the surface of the test piece 1 on which the coating films (Examples 1 to 7 and Comparative Example 1) were formed. The evaluation criteria are as follows.

A: Pattern width exceeds 300 mm O: Pattern width is 250 to 300 mm
Δ: Pattern width is 200 to 249 mm
X: Pattern width is less than 200 mm (B: Adhesiveness)
The cutting tool was vertically applied to the surface of the coating film of the test piece 1 and five parallel lines with a distance of 4 mm were drawn at a depth reaching the substrate, and five perpendicular lines intersecting the parallel lines were drawn with a distance of 4 mm. Adhesive tape was applied to the grid, and the peeled state was evaluated by rapidly pulling the adhesive tape from the coating film.

◎: No peeling ○: Peeling area is less than 5% △: Peeling area is 5-15%
X: peeling area exceeds 15% (C: chipping resistance)
In the stepping stone testing machine defined in the ASTM D3170 standard, the test piece 1 kept at a constant temperature of −20 ° C. and 20 ° C. is installed, and 500 g of single-grain crushed stone (size 10-15 mm) defined in JIS A 5001 is applied at a pressure of 500 KPa. Hit the coating surface of each test piece 5 times. Then, after performing the salt spray test of JIS Z 2371 standard for 168 hours, the rusting state and the peeling state were evaluated.

◎: No peeling of 3 mm or more in diameter and the number of rusting is less than 5 ○: No peeling of 3 mm or more in diameter and 5 to 10 rusting △: No peeling of 3 mm or more in diameter, 11 rusting -15 pieces x: There is no peeling of 3 mm or more in diameter, and the number of rusting exceeds 15 pieces (D: corrosion resistance)
A test piece in which a cutting tool is vertically applied to the coating film surface of each test piece 1 and a cross cut (length: 40 mm, 30 degrees) is inserted to reach the base material is subjected to a salt spray test of JIS Z 2371 standard for 480 hours. The state of occurrence of red rust and the state of swelling and peeling of the coating film were evaluated.

◎: No occurrence of red rust, no swelling of coating film ○: Base rust from the cross-cut part and swelling of the coating film are less than 2 mm on one side Δ: Base rust from the cross-cut part and swelling of the coating film are on one side 2 ~ 3mm
X: Base rust from the cross cut part and swelling expansion of the coating exceeds 3 mm on one side (E: Damping property)
For each of the above test pieces 2 (coating film thickness: 600 μm), the number loss for each film thickness is determined by the half-width method at the secondary resonance point using a cantilever beam loss factor measuring machine (manufactured by Bruel & Care). The coefficient (η) was measured and evaluated (measurement temperature 20 ° C.).

A: Loss coefficient exceeds 0.02 when the coating film thickness is 600 μm B: Loss coefficient is 0.015 to 0.02 when the coating film thickness is 600 μm
Δ: Loss coefficient of 0.01 to 0.014 when the coating film thickness is 600 μm
×: Loss coefficient is less than 0.01 when the coating film thickness is 600 μm (F: comprehensive judgment)
Table 2 shows the results of the comparative experiments A to E described above.

  It judged comprehensively from the test result of AE. In the overall judgment, “x” means that “x” is at least one, “○” means that there is at least one “△”, and “◎” means that all items are “○” or more. Respectively.

  From this experimental result, as the mica is increased, the vibration damping property is improved, but conversely, the paintability and the adhesion are deteriorated, and the relationship between the appropriate amount of mica is found.

  Next, the room sound pressure level was measured in order to examine the frequency region where the uncomfortable sound actually occurs.

(G: room sound pressure level)
A fuel tank coated with the paint of Comparative Example 1 with an average film thickness of 600 μm is mounted on a vehicle (tank capacity is about 50 L) that can mount an engine with a displacement of 1500 cc to 2500 cc, and a fuel pipe (fuel inlet or filler pipe) is installed. The fuel oil equivalent to point E is injected into the fuel tank, and a precision microphone (made by Brüel & Care) is installed in the center of the car. When the vehicle engine is operating (idling), when idling is stopped (engine is not operating, electromagnetic The sound pressure level was measured for the pump only. In the sound pressure level measurement of each of the examples and comparative examples, the fuel oil was appropriately added and adjusted so that the amount of the fuel oil in the fuel tank was equivalent to the E point.

  And it replaced with the coating film of the comparative example 1, and performed the same experiment with the coating film of Example 1,3,6. It should be noted that the same experiment may be performed for all the other embodiments. However, it is difficult to carry out the experiment by mounting on each vehicle, which requires a lot of man-hours and costs. Substituted with.

  The result of this experiment is shown in FIG. When the experimental result of FIG. 2 is seen with the coating film of Comparative Example 1, the sound pressure level is high at any frequency band of 100 to 1000 Hz when idling, but the sound pressure level is generally low when idling is stopped. Results are shown. However, in the frequency band of 100 to 200 Hz, the sound pressure level suddenly increases like a mountain, and it can be said that this sound pressure level is an annoying sound (unpleasant sound).

  On the other hand, in Examples 1, 3 and 6, the sound pressure level in this region, that is, the frequency band of 100 to 200 Hz, is lowered and the height of the mountain is gentle, so that the sound is not harsh. I can say that.

  As described above, in the frequency band of 100 to 200 Hz, the first, third, and sixth examples have a lower sound pressure level than the comparative example 1, and in the frequency band of 200 to 1000 Hz, the examples 1, 3 and 6 show the same sound pressure level as in Comparative Example 1, and it can be seen that it is very good to add mica to the coating film on the casing of the fuel tank.

  In addition, the rust preventive pigment, the color pigment, and the stabilizer are generally contained in the coating film, and the numerical range is also a normal range, and the experiment with components having different ranges was intentionally omitted.

  The present invention is a metal fuel tank for automobiles with a coating film excellent in chipping resistance coated on the outer surface, which transmits the operating sound of an electric pump built in the fuel tank, particularly when idling is stopped. The present invention can be applied to an automobile fuel tank that reduces the transmission of pump operating noise to the outside.

Claims (4)

In a fuel tank for an automobile in which an electric pump for supplying fuel to an engine is installed in a fuel tank formed of a casing formed of a metal-based sheet material, and the electric pump in the fuel tank is operating when idling is stopped. ,
The outer surface of the casing is coated with a chipping-resistant coating film,
When the coating film for chipping resistance is in the range of 10 to 30% by mass of vinyl chloride resin or 10 to 30% by mass of acrylic resin, the total value of the vinyl chloride resin or the acrylic resin alone or mixed is 10 to 30%. Based on mass%,
The chipping-resistant coating film includes 7.5 to 15.0% by mass of mica powder that reduces transmission of operating sound in the frequency band of 100 Hz to 200 Hz of the electric pump when the idling is stopped . A fuel tank for automobiles characterized by being mixed in range . In claim 1,
The coating film for chipping resistance is 15 to 40% by mass of a plasticizer, 0 to 50% by mass of calcium carbonate, 0.1 to 15% by mass of an adhesion-imparting agent, and 1 to A fuel tank for an automobile, comprising 15% by mass, 0.1 to 1.0% by mass of a color pigment, 0.1 to 5% by mass of a stabilizer, and 1 to 5% by mass of a lightweight aggregate . In claim 1 or 2,
The automobile fuel tank , wherein the mica powder has an aspect ratio of 50 (50: 1) or more and a particle diameter (length) of 10 to 200 μm . In any one of Claims 1 thru | or 3 ,
The automotive fuel tank, wherein a film thickness of the anti-chipping coating film is 300 to 2000 μm.

Images