JP2020117010A - Saddle type resin fuel tank - Google Patents

Abstract

To provide a saddle type resin fuel tank which shortens a molding cycle time.SOLUTION: There is provided a saddle type resin fuel tank 1 that stores a fuel 43 supplied to an internal combustion engine mounted on a vehicle in a chamber having a saddle-shaped part 2 between a first chamber 3 and a second chamber 4, in which an arc-shaped part 16 in a deeply throttled region 15 of the saddle-shaped part 2 has a wavy-shaped part 20 in a cross section. A film thickness in a wavy-shaped part 20 of the saddle-shaped part 2 is formed so that a trough part 22 of the wavy-shaped part 20 is thinner than a mountain part 21 of the wavy-shaped part 2, and a film thickness of the mountain part 21 is the same as a film thickness in a portion other than the deeply throttled region 15.SELECTED DRAWING: Figure 2

Description

The present invention relates to a saddle-shaped resin fuel tank, which shortens a molding cycle time, in particular.

As a fuel tank for an automobile, a resin-made fuel tank that contributes to weight reduction and expansion of the vehicle interior space is used, and the resin-made fuel tank is mainly manufactured by blow molding. In addition, as a material, high density polyethylene (HDPE) is used as a main material, and for example, an ethylene-vinyl alcohol copolymer (EvOH) is used for the barrier layer having extremely low fuel permeability. And the structure is from the inside of the fuel tank, 3 types of 5 layers of main material/adhesive layer/barrier layer/adhesive layer/main material, main material/adhesive layer/barrier layer/adhesive layer/recycled It has a structure of 4 types and 6 layers of material layer/main material structure. Built-in parts such as valves and baffle plates for suppressing the flow noise of fuel may be provided in the fuel tank.

As a method of manufacturing a resin fuel tank by blow molding, according to Patent Document 1, a cavity for forming a resin molded product is formed on the opening and closing surface, and a molding split mold divided by a parting line is used. Open the split mold with a parting line, push the parison into a hollow shape from the die core, place it on the cavity, and then insert the built-in component holding device with the built-in components mounted between the parison to insert the built-in components into the inner surface of the parison. , A method of performing blow molding by closing the molding split mold after removing the built-in component holding device.

On the other hand, in blow molding, when molding a molding object such as a parison, the mold is in contact with the outside of the molding object, so it takes a long time to cool the molding object after molding, and it is possible to cool it efficiently. It was difficult to do. Therefore, in Patent Document 2, as shown in FIG. 5, a parison discharged from the crosshead 500 or a pair of sheets obtained by cutting the parison or a molded object 510 formed of the pair of sheets is provided inside an inner cooling mold 520. With the inserted state (A), the outer mold 530 located outside the molded body 510 is closed (B), the molded body 510 is cooled, and then the outer mold 530 is opened (C), the inner cooling metal mold A method of shortening the molding cycle time by releasing the mold 520 from the inside of the molded object 510 (D), then closing the outer mold 530 again and molding the molded object 510 (E) is disclosed. There is.

By the way, generally, in front-engine/rear-drive FR vehicles and four-wheel drive (4WD, AWD) vehicles, the propeller shaft that transmits the driving force of the engine to the rear differential gearbox extends to the lower part of the vehicle body. doing. The propeller shaft is usually arranged at the center of the vehicle body in order to balance the drive system. Therefore, the fuel tank placed under the rear seat, etc. is formed in a so-called saddle shape in which the fuel chamber is divided into left and right parts by projecting the approximately central part of the bottom surface of the tank upward so as not to interfere with the propeller shaft. To be done.

As shown in FIG. 6, a saddle-shaped resin fuel tank 100 mounted on a vehicle includes a saddle-shaped portion 200 in which a central portion 140 of a lower wall portion 120 of the resin fuel tank 100 protrudes upward in an arc shape. It is composed of a first chamber 300 and a second chamber 400 that store fuel in the vehicle width direction with the saddle-shaped portion 200 interposed therebetween (Patent Document 3).

Regarding the cross-sectional shape of the upper wall portion 110 of the saddle-shaped portion 200 in the saddle-shaped resin fuel tank, the upper wall portion 110 of the saddle-shaped portion 200 is the upper wall of the first chamber 300 as shown in FIG. In addition to the type in which the portion 110 and the upper wall portion 110 of the second chamber 400 are raised in the vertical direction, a substantially same surface as the upper wall portion of the first chamber and the upper wall portion of the second chamber is formed. And the upper wall part 110 of the saddle-shaped part 200 is recessed in the vertical direction as compared with the upper wall part of the first chamber and the upper wall part of the second chamber.

JP, 2016-047635, A JP, 2012-218212, A JP, 2008-094967, A

By the way, when the saddle type resin fuel tank 100 as shown in FIG. 6 is manufactured by blow molding, the deeply narrowed region 150 of the lower wall portion 120 formed in the central portion 140 of the resin fuel tank 100, The thickness of the arcuate portion 160 at the top is formed thicker than other portions due to the locally different degree of extension of the parison. As a result, there is a problem that the cooling time becomes long and the molding time becomes long.

It is difficult to apply the inner cooling mold 520 in Patent Document 2 to a saddle-shaped resin fuel tank, and even if it is applicable, the cost of the inner cooling mold 520 and the molding time using the same. It becomes a factor of cost increase.

Therefore, the present invention is to provide a saddle-shaped resin fuel tank that shortens the molding cycle time.

In order to solve the above-mentioned problems, the present invention according to claim 1 is a saddle type that stores fuel supplied to an internal combustion engine mounted on a vehicle in a room having a saddle-shaped portion between the first chamber and the second chamber. A saddle-shaped resin fuel tank, wherein the saddle-shaped portion has a corrugated portion in a cross section.

According to the first aspect of the present invention, a saddle-type resin fuel tank for storing fuel supplied to an internal combustion engine such as an engine mounted on a vehicle in a room having a saddle-shaped portion between the first chamber and the second chamber In addition, since the saddle-shaped portion has the corrugated portion in the cross section, the local variation in the extension degree of the parison is alleviated. As a result, the film thickness of the deeply squeezed region formed in the saddle-shaped portion at the substantially central portion of the resin fuel tank is extended and thinned to almost the same film thickness as the other portions, and further, the wavy shape is formed. By doing so, the contact area with the mold to be cooled is increased, so that the cooling time can be shortened.
Further, the corrugated portion increases the mechanical strength of the deeply squeezed region formed in the saddle-shaped portion at the substantially central portion of the resin fuel tank.

Furthermore, as a result of the corrugated portion increasing the mechanical strength of the deeply squeezed region formed in the saddle-shaped portion of the center of the resin fuel tank, the molding split mold is opened at a higher temperature than before, It becomes possible to shift to the next step, for example, drilling, mounting of built-in parts, etc., and the manufacturing time of the resin fuel tank can be shortened.

In addition, the wave shape refers to a shape that undulates up and down like a wave, and shows the temporal change of the physical quantity at a fixed position when the wave propagates or the spatial change of the physical quantity at a fixed time. In addition to a sine wave and a triangular wave, it refers to a shape in which an upward convex arc and a downward convex arc are continuously connected.

The present invention according to claim 2 is a saddle-type resin fuel tank in which the corrugated portion of the saddle-shaped portion is formed in the arc-shaped portion at the top of the deeply narrowed region of the saddle-shaped portion. In the saddle type resin fuel tank, a deeply squeezed region protruding upward is formed in the lower wall part of the saddle-shaped part because it straddles the propeller shaft etc., reflecting the cross-sectional shape of the propeller shaft etc. An arcuate portion is formed at the upper end portion (depth tip portion) of the deeply squeezed region, that is, at the top. Then, the arc-shaped portion is formed to be thicker than the other portions.

According to the present invention of claim 2, since the corrugated portion of the saddle-shaped portion is formed in the arc-shaped portion at the top of the deeply squeezed region of the saddle-shaped portion, the local variation of the extension degree of the parison is alleviated. .. As a result, the thickness of the arc-shaped portion at the top of the deeply squeezed region formed in the saddle-shaped portion at the center of the saddle-shaped resin fuel tank is stretched to be almost the same as the thickness of the other portions and thinned. In addition, since the wavy shape increases the contact area with the cooled mold, the cooling time can be shortened. In addition, the corrugated portion increases the mechanical strength of the deeply squeezed region formed in the saddle portion at the center of the resin fuel tank.

According to the present invention of claim 3, the corrugated portion of the saddle-shaped portion is a saddle-type resin fuel tank formed in the vehicle width direction and/or the vehicle front-rear direction. As described above, by forming the corrugated portion in the saddle-shaped portion, the thickness of the saddle-shaped portion is extended to be almost the same as the thickness of the other portions, and the cooling time is shortened and the saddle-shaped portion is reduced. Increases the mechanical strength of.

According to the present invention of claim 3, since the corrugated portion of the saddle-shaped portion is formed in the vehicle width direction of the vehicle and/or in the front-rear direction of the vehicle, the saddle-shaped portion is centered in the vehicle width direction of the vehicle. It is possible to prevent the first chamber and the second chamber formed on the left and right of the saddle-shaped portion from bending downward in the vehicle. Further, by forming the corrugated portion in the front-back direction of the vehicle together with the vehicle width direction of the vehicle, the strength of the resin-made fuel tank against twisting due to the twisting of the vehicle increases.

The present invention according to claim 4 is the saddle-type resin fuel tank, wherein the corrugated portion of the saddle-shaped portion has a film thickness in which the valley portion of the corrugated portion is thinner than the peak portion of the corrugated portion. .. According to the present invention of claim 4, as for the film thickness in the corrugated portion of the saddle-shaped portion, the local variation in the degree of extension of the parison is relaxed, and as a result, the valley portion of the corrugated portion is larger than the peak portion of the corrugated portion. Since it is formed thin, the thin portion is intermittently formed in the corrugated portion, and the cooling time can be further shortened. Even when a thin portion is intermittently formed in the corrugated portion, the corrugated portion increases the mechanical strength of the saddle-shaped portion. Is no problem.

Here, the troughs and the peaks in the corrugated portion refer to the downward direction of the vehicle body with respect to the vertical direction of the vehicle body when the saddle-shaped resin fuel tank is mounted on the vehicle among the two top portions of the corrugated portion. The top of the corrugated portion on the side is referred to as a valley portion, and the top of the corrugated portion on the upward side of the vehicle body is referred to as a mountain portion.

In the saddle-shaped resin fuel tank, since the saddle-shaped portion is formed with the corrugated portion in the cross section, the local fluctuation of the extension degree of the parison is alleviated, and the saddle in the substantially central portion of the resin fuel tank is relaxed. The film thickness of the arc-shaped part at the top of the deeply constricted region formed in the corrugated part is extended and thinned to almost the same as the other parts, and further, the corrugated shape makes contact with the cooled mold. Since the area is increased, the cooling time can be shortened.

The corrugated portion increases the mechanical strength of the deeply squeezed region formed in the saddle-shaped portion at the substantially central portion of the resin fuel tank. In addition, as a result of the increased mechanical strength of the saddle-shaped part, it becomes possible to open the molding split mold at a higher temperature than before, and move on to drilling in the next process, mounting internal parts, etc. The manufacturing time of the tank can be shortened.

The film thickness in the corrugated portion of the saddle-shaped portion is corrugated because the troughs of the corrugated portion are formed thinner than the peaks of the corrugated portion because local fluctuations in the degree of extension of the parison are alleviated. The thin portion is intermittently formed in the portion, and the cooling time can be further shortened.

It is an outer shape of a saddle-shaped resin fuel tank. It is a cross-sectional schematic diagram of a saddle-shaped resin fuel tank. FIG. 3 is an embodiment of the present invention, and is a schematic cross-sectional view of a corrugated portion in which the vicinity of the deeply narrowed region 15 of FIG. 2 is enlarged. It is an embodiment of the present invention, and is a view of a molding split die in which a wave shape is formed and a resin portion after molding. It is sectional explanatory drawing of the method and apparatus which shorten the cooling time in the conventional blow molding (patent document 2). It is a cross-sectional schematic diagram of the conventional saddle type resin fuel tank (patent document 3).

A saddle type resin fuel tank 1 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4. Note that FIG. 4 is a diagram created based on the photograph.
As shown in FIGS. 1 and 2, a saddle-shaped resin fuel tank 1 has a saddle-like structure that connects a first chamber 3 that is a main tank portion, a second chamber 4 that is a sub tank portion, and a central portion 14 that connects them. It consists of part 2. The outer walls of the first chamber 3, the second chamber 4, and the saddle-shaped part 2 are molded by blow molding using a molding die (not shown) divided into an upper wall part 11 and a lower wall part 12, The wall portion 11 and the lower wall portion 12 are connected by a connecting portion 13 on the side surface.

The lower wall portion 12 of the saddle-shaped portion 2 projects upward in an arc shape inside the resin fuel tank 1, and below the saddle-shaped portion 2 is an exhaust pipe (not shown) from the propeller shaft 42 and the engine 41. Form a space for arranging). A full tank detection valve 44 is arranged on the upper wall portion 11 of the saddle-shaped portion 2. Further, the lower wall portion 12 of the saddle-shaped portion 2 has a deeply narrowed region 15 protruding upward in an arc shape, and the arc-shaped portion 16 at the top of the deeply narrowed region 15 has a structure shown in FIG. The corrugated portion 20 is formed as shown in (a schematic cross-sectional view showing the positional relationship between the deeply narrowed region 15 of the portion 2 and the corrugated portion 20). In addition, in this embodiment, the corrugated portion 20 is formed in the vehicle width direction of the vehicle. The corrugated portion 20 will be described later in detail.

A fuel pump 45 for transferring the fuel 43 to the engine 41 is arranged in the first chamber 3, which is the main tank portion. A jet pump 46 is arranged in the pipe between the engine 41 and the first chamber 3, and the pipe from the jet pump 46 further extends to the second chamber 4.

When the fuel pump 45 operates with the start of the engine 41, the fuel 43 in the first chamber 3 is transferred to the engine 41. At the same time, the jet pump 46 is operated by using the flow velocity of the fuel transferred to the engine 41 by the fuel pump 45, and the fuel 43 is sucked up from the second chamber 4 by the Venturi effect, and the fuel 43 is transferred to the engine 41. Be transferred to.

The saddle-shaped resin fuel tank 1 is mainly made of high-density polyethylene (HDPE), and the barrier layer having extremely low fuel permeability is made of, for example, ethylene-vinyl alcohol copolymer (EvOH). From the inside of the fuel tank 1, it is composed of 4 types and 6 layers of main material/adhesive layer/barrier layer/adhesive layer/recycled material layer/main material structure. It is also possible to use 5 layers of 3 types of main material/adhesive layer/barrier layer/adhesive layer/main material.

The saddle-shaped resin fuel tank 1 has a cavity 31 for forming a resin molded product on the opening and closing surface and uses a molding split mold 30 divided by a parting line, as in Patent Document 1. Open with a parting line, and extrude the parison of the above structure hollowly from the die core and place it on the cavity 31 and then insert the built-in parts holding device with built-in parts mounted between the above parison to insert the built-in parts into the parison. It is attached to the inner surface of the device, and after removing the built-in component holding device, the molding split mold 30 is closed and blow molding is performed. The built-in parts may be assembled by forming a hole in the upper wall portion 11 of the saddle-shaped resin fuel tank 1 after molding and inserting the hole through the hole.

As shown in FIG. 4, the cavity 31 of the molding die 30 for forming the corrugated portion 20 of the lower wall portion 12 of the saddle-shaped resin fuel tank 1 has a cycle of 25 mm and a width (amplitude). A 5 mm sinusoidal shape is formed.

As a result of blow molding using the above molding split mold 30 under the same conditions as before, as shown in FIG. 4, the corrugated portion 20 has a thick film thickness portion (about 8 mm) and a thick film thickness portion. It can be seen that a thin part (about 5 mm) is formed. Further, it can be seen that the thickness of the thick portion of the corrugated portion 20 is the same as the thickness of the straight portion on the right side of FIG.

In FIG. 4, the thick portion corresponds to the peak portion 21 of the corrugated portion 20, and the thin portion corresponds to the valley portion 22 of the corrugated portion 20. This is, as described above, the troughs and the peaks in the corrugated portion are the two tops of the corrugated portion in the vertical direction of the vehicle body when the saddle type resin fuel tank is mounted on the vehicle. This is because the top of the vehicle body on the lower side is called a valley and the top of the vehicle body on the upper side is called a mountain.

When a sine wave shape is used in the cavity 31 of the molding split mold 30, the cycle is preferably 10 mm to 50 mm, and the width (amplitude) is preferably 5 mm to 20 mm. If the period is less than 10 mm or more than 50 mm, the local variation in the degree of extension of the parison is not sufficiently mitigated, and the effect of the present invention is difficult to obtain, and it projects upward in an arc shape inside the saddle-shaped portion 2. The film thickness of the peak portion 21 is formed to be thick as before.

Further, if the width (amplitude) is less than 5 mm, it is difficult to obtain the effect of the present invention. If the width (amplitude) is more than 20 mm, the degree of expansion of the parison that constitutes the resin fuel tank 1 is locally varied, and the wave length increases. The peak portion 21 of the shaped portion 20 has a small thickness, and a predetermined thickness cannot be obtained. In addition, regarding these periods and swing widths, almost the same tendency is shown in the case of a triangular wave, or in the case where an upward convex arc and a downward convex arc are continuously connected.

As a result, local fluctuations in the degree of extension of the parison in the deeply squeezed region formed in the saddle-shaped portion of the resin fuel tank are alleviated, and the film thickness of the deeply squeezed region is extended, The cooling time was able to be shortened by about 20% as compared with the case where there is no corrugated portion, by forming a portion which is almost the same as or thinner than other portions.

Further, since the corrugated portion increases the mechanical strength of the deeply squeezed region formed in the saddle-shaped portion at the center of the resin fuel tank, the saddle-shaped portion is centered in the vehicle width direction of the vehicle. It was possible to prevent the first chamber and the second chamber formed on the left and right of the saddle-shaped portion from bending downward in the vehicle. In addition, the corrugated portion may be formed in the front-rear direction of the vehicle, and in this case, the strength against the twist of the resin fuel tank due to the twist of the vehicle also increases.

In addition, since the corrugated portion increases the mechanical strength of the deeply squeezed region formed in the saddle portion at the center of the resin fuel tank, the molding split mold is opened at a higher temperature than before, It became possible to shift to the drilling process in the next process and the mounting of built-in parts, and it was possible to further reduce the manufacturing time of the resin fuel tank.

The embodiment of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the object of the present invention.

In the above-described embodiment of the present invention, the lower wall portion 12 of the saddle-shaped portion 2 is formed so as to project upward in an arc shape inside the resin fuel tank 1, but the exhaust from the propeller shaft 42 and the engine 41 is exhausted. Depending on the arrangement of the pipes (not shown), the shape of the lower wall portion 12 of the saddle-shaped portion 2 protruding upward inward of the resin fuel tank 1 is not an arc shape but another arc shape or an arc shape. The shape may have a part of straight line added. In this case as well, when formed without the corrugated portion 20, the film of the portion (the deeply squeezed region 15) of the lower wall portion 12 of the saddle portion 2 that protrudes upward inside the resin fuel tank 1 is formed. The present invention can be applied when the thickness is thicker than other portions.

In the above-described embodiment of the present invention, with respect to the saddle type resin fuel tank 1, the saddle-shaped portion 2 forms the same surface as the upper wall portion 11 of the first chamber 3 and the upper wall portion 11 of the second chamber 4. The inside of the saddle-shaped portion 2 formed on the lower wall portion 12 of the present type has the corrugated portion 20 on the arc-shaped portion 16 at the top of the deeply narrowed region 15. Compared to the upper wall portion 110 of the chamber 300 and the upper wall portion 110 of the second chamber 400, the type that rises in the vertical direction, the upper wall portion 110 of the first chamber 300, and the upper wall portion 110 of the second chamber 400. Compared with the above, the present invention can be applied to the saddle-shaped portion 200 formed on the upper wall portion 110 of the type that is vertically recessed.

1, 100 saddle type resin fuel tank 2, 200 saddle-shaped part 3, 300 first chamber 4, 400 second chamber 11, 110 upper wall part 12, 120 lower wall part 13 connecting part 14, 140 central part 15, 150 Deeply squeezed regions 16 and 160 Arc-shaped portion 20 Wave-shaped portion 21 Crest portion 22 Valley portion 30 Molding split mold 31 Cavity 41 Engine 42 Propeller shaft 43 Fuel 44 Full tank detection valve 45 Fuel pump 46 Jet pump

Claims (4)

A saddle-type resin fuel tank for storing fuel supplied to an internal combustion engine mounted on a vehicle in a room having a saddle-shaped portion between the first chamber and the second chamber,
The saddle-shaped resin fuel tank, wherein the saddle-shaped portion has a corrugated portion in cross section. The saddle-shaped resin fuel tank according to claim 1, wherein the corrugated portion of the saddle-shaped portion is formed in an arc-shaped portion at the top of a deeply narrowed region of the saddle-shaped portion. The saddle type resin fuel tank according to claim 1 or 2, wherein the corrugated portion of the saddle-shaped portion is formed in a vehicle width direction and/or a vehicle front-rear direction. The film thickness in the corrugated portion of the saddle-shaped portion is defined by any one of claims 1 to 3, wherein a valley portion of the corrugated portion is formed thinner than a peak portion of the corrugated portion. The saddle-shaped resin fuel tank described.

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