A polymer oil tank and its molding die and hydraulic system

Abstract

The utility model discloses a polymer oil tank, including a tank body and a partition. The tank body is made of polymer material, which is conducive to reducing the weight of the tank. The metal bracket and the tank body are integrally formed by rotational molding, and a partition is formed in the inner cavity of the tank body, which effectively enhances the structural strength of the polymer oil tank and improves the adaptability of the polymer oil tank. The partition divides the inner cavity of the tank body into multiple cavities, and a through hole is provided on the partition to connect the separated cavities. The partition can reduce the impact caused by the shaking of oil in the tank body, and at the same time play the role of diversion and defoaming, so as to ensure the normal operation of the polymer oil tank. The utility model also provides a molding mold of the above-mentioned polymer oil tank to realize the integral rotational molding of the polymer oil tank. The utility model also provides a hydraulic system, including the above-mentioned polymer oil tank, to improve the performance of the hydraulic system and ensure the normal operation of the hydraulic system.

Description

Technical Field

[0001] The utility model relates to the technical field of hydraulic systems and peripheral supporting facilities, in particular to a polymer oil tank and a molding die thereof and a hydraulic system. Background Art

[0002] In addition to storing oil, the oil tank in the hydraulic system also plays the role of heat dissipation, separating bubbles in the oil, and precipitating impurities. Oil tanks are divided into iron oil tanks, aluminum alloy oil tanks, and polymer oil tanks according to their materials. With the application and development of various new materials, the rust prevention of iron oil tanks has become the biggest problem of oil tank quality. Especially today when we pay attention to environmental protection.

[0003] In the heavy truck industry, the quality of the fuel tank, which is the most critical part of fuel storage, has become a key issue. Polymer fuel tanks not only meet the requirements in terms of strength, but also have great advantages in corrosion resistance over iron and other new materials. They have also become the first choice for large buses and heavy trucks that consume a lot of fuel and have high requirements for fuel quality.

[0004] The existing polymer fuel tanks cannot have partitions (wave-breaking plates) inside the tank, and the upper limit of the volume is within 80L, so the use scenarios are limited. Another type of fuel tank is mostly made of metal tanks. On the one hand, the metal tank itself has poor corrosion resistance and a short service life; on the other hand, the metal tank has a large deadweight, the vehicle has high fuel consumption, and poor economy. Utility Model Content

[0005] The purpose of the utility model is to provide a polymer oil tank and its molding die and hydraulic system to solve the problems existing in the above-mentioned prior art, improve the structural strength and corrosion resistance of the oil tank, reduce the weight of the oil tank and reduce energy consumption.

[0006] To achieve the above purpose, the utility model provides the following solutions:

[0007] The utility model provides a polymer oil tank, comprising an oil tank body, wherein the oil tank body has a refueling port, an oil suction port, an air outlet and an oil drain port, wherein the refueling port, the oil suction port, the air outlet and the oil drain port are all connected to the inner cavity of the oil tank body; the oil tank body is made of a polymer material, and further comprises:

[0008] A partition, wherein the partition is arranged in the inner cavity of the oil tank body, and the partition includes a metal bracket, and the metal bracket is rotationally molded into one piece with the oil tank body to form the partition; the number of the partitions is at least two groups; and the partition has a through hole to connect the cavities on both sides of the partition.

[0009] Preferably, the metal bracket includes a main body, the main body includes a flat plate and a curved plate, the flat plate is connected to the curved plate, a through hole is provided on the flat plate, and a protrusion of the curved plate is arranged toward the center of the tank body.

[0010] Preferably, the number of the flat panels and the number of the curved panels are both multiple, and the flat panels and the curved panels are arranged at intervals in the horizontal direction;

[0011] There are multiple through holes on each of the planar plates, and the multiple through holes are evenly distributed along the length direction of the planar plate.

[0012] Preferably, the metal bracket also includes a first connecting part and a second connecting part, the first connecting part is arranged on the left and right sides of the main body, and a bending plate is arranged on the side of the first connecting part away from the main body, and the bending plate extends toward the convex direction of the arc panel; the second connecting part is arranged at the upper and lower ends of the main body, the flat plate and the arc panel are both connected to the second connecting part, and the second connecting part extends toward the convex direction of the arc panel; the first connecting part and the second connecting part can be fixed in the cavity of the rotational molding mold.

[0013] Preferably, when the metal bracket is fixed in the cavity of the rotational molding mold, the gap between the first connecting part and the second connecting part and the rotational molding mold is 0.5-1.2 times the wall thickness of the finished polymer oil tank; the thickness of the metal bracket is 2.0-4.5 times the wall thickness of the finished polymer oil tank, and the size ratio of the finished polymer oil tank adopts a ratio of 0.8 / 3.0 to achieve internal partition and connection of the cavity.

[0014] Preferably, the first connecting portion is a hollow structure, and both the first connecting portion and the second connecting portion are provided with reinforcement holes, and the reinforcement holes are waist-shaped holes.

[0015] Preferably, connecting nuts are provided on the bending plates of the first connecting part and the second connecting part, the threaded holes of the connecting nuts are blind holes, and the first connecting part and the second connecting part can be fixed in the cavity of the rotational molding mold by using the connecting nuts.

[0016] Preferably, guide plates are provided at four corners of the main body, the guide plates are located between the first connecting portion and the second connecting portion, and the guide plates extend from the main body toward the center of the oil tank body.

[0017] Preferably, both the side walls and the bottom wall of the fuel tank body have groove-shaped depressions to form reinforcing ribs in the inner cavity of the fuel tank body.

[0018] The utility model also provides a molding mold for the above-mentioned polymer oil tank, including an upper mold, a lower mold and a positioning pin. The upper mold and the lower mold form a cavity matching the oil tank body. The metal bracket can be detachably connected to the positioning pin to fix the metal bracket and be separated from the metal bracket after the polymer oil tank is formed.

[0019] Furthermore, the utility model also provides a hydraulic system, comprising the above-mentioned polymer oil tank.

[0020] Compared with the prior art, the utility model has achieved the following technical effects: the polymer oil tank of the utility model includes a oil tank body and a partition, the oil tank body is made of polymer material, the partition is arranged in the inner cavity of the oil tank body, the partition includes a metal bracket, the metal bracket and the oil tank body are rotationally molded as one body to form a partition; the number of partitions is at least two groups; the partition is provided with through holes to connect the cavities on both sides of the partition; the oil tank body has a refueling port, an oil suction port, an air outlet and an oil drain port, and the refueling port, the oil suction port, the air outlet and the oil drain port are all connected with the inner cavity of the oil tank body.

[0021] The polymer fuel tank of the utility model is made of a fuel tank body of polymer material, which is conducive to reducing the weight of the fuel tank. The metal bracket and the fuel tank body are rotationally molded as one piece, and a partition is formed in the inner cavity of the fuel tank body, which effectively enhances the structural strength of the polymer fuel tank and improves the adaptability of the polymer fuel tank. The partition divides the inner cavity of the fuel tank body into a plurality of cavities, and a through hole is provided on the partition to connect the separated cavities to ensure the working capacity of the polymer fuel tank. The partition can reduce the impact caused by the shaking of oil in the fuel tank body. The partition also plays the role of wave prevention, flow diversion and defoaming, thereby ensuring the normal operation of the polymer fuel tank.

[0022] The utility model also provides a molding die for the polymer oil tank, which realizes the integral rotational molding of the polymer oil tank.

[0023] The utility model also provides a hydraulic system, including the above-mentioned polymer oil tank, which improves the performance of the hydraulic system and ensures the normal operation of the hydraulic system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 This is a schematic diagram of the structure of the polymer fuel tank disclosed in the embodiment of the utility model;

[0026] Figure 2 It is a schematic structural diagram of the polymer fuel tank disclosed in the embodiment of the utility model from other angles;

[0027] Figure 3 A schematic diagram of the internal structure of the polymer fuel tank disclosed in the embodiment of the utility model;

[0028] Figure 4 This is a schematic diagram of the main structure of the metal bracket of the polymer oil tank disclosed in the embodiment of the utility model;

[0029] Figure 5 A schematic top view of a metal bracket of a polymer fuel tank disclosed in an embodiment of the utility model;

[0030] Figure 6 This is a schematic diagram of the disassembled structure of the metal bracket of the polymer fuel tank disclosed in the embodiment of the utility model;

[0031] Figure 7 The figure is a working schematic diagram of the molding die of the polymer fuel tank disclosed in the embodiment of the utility model.

[0032] In the figure: 100, polymer fuel tank; 200, forming mold;

[0033] 1. Fuel tank body; 2. Partition; 3. Metal bracket; 4. Through hole; 5. Fuel filling port; 6. Fuel suction port; 7. Air outlet; 8. Fuel drain port; 9. Main body; 10. First connecting part; 11. Second connecting part; 12. Arc panel; 13. Flat panel; 14. Connecting nut; 15. Guide plate; 16. Reinforcement rib; 17. Upper die; 18. Lower die; 19. Positioning pin; 20. Slider; 21. Bending plate; 22. Reinforcement hole. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0035] The purpose of the utility model is to provide a polymer oil tank and its molding die and hydraulic system to solve the problems existing in the above-mentioned prior art, improve the structural strength and corrosion resistance of the oil tank, reduce the weight of the oil tank and reduce energy consumption.

[0036] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0037] Embodiment 1

[0038] The present embodiment provides a polymer oil tank 100, including an oil tank body 1 and a partition 2, the oil tank body 1 is made of polymer material, the partition 2 is arranged in the inner cavity of the oil tank body 1, the partition 2 includes a metal bracket 3, the metal bracket 3 and the oil tank body 1 are rotationally molded as one body to form the partition 2; the number of partitions 2 is at least two groups; the partition 2 is provided with a through hole 4 to connect the cavities on both sides of the partition 2; the oil tank body 1 has a refueling port 5, an oil suction port 6, an air outlet 7 and an oil drain port 8, and the refueling port 5, the oil suction port 6, the air outlet 7 and the oil drain port 8 are all connected to the inner cavity of the oil tank body 1.

[0039] The polymer fuel tank 100 of the utility model, the fuel tank body 1 is made of polymer material, which is beneficial to reducing the weight of the fuel tank, the metal bracket 3 and the fuel tank body 1 are rotationally molded as one, which improves the structural integrity of the polymer fuel tank 100, and a partition 2 is formed in the inner cavity of the fuel tank body 1 after rotational molding, which effectively enhances the structural strength of the polymer fuel tank 100; the partition 2 divides the inner cavity of the fuel tank body 1 into a plurality of cavities, reduces the impact caused by the shaking of oil in the fuel tank body 1, and plays the role of wave prevention, diversion and defoaming, and the partition 2 is provided with a through hole 4 to connect the separated cavities, ensure the normal operation of the polymer fuel tank 100, and improve the adaptability of the polymer fuel tank 100.

[0040] In this specific embodiment, the number of the partitions 2 is two groups, with the center line of the fuel tank body 1 as the symmetry axis, and the two partitions 2 are symmetrically arranged in the inner cavity of the fuel tank body 1, so as to enhance the structural strength of the polymer fuel tank 100. Compared with the fuel tank made of metal material, the polymer fuel tank 100 of the utility model has a smaller mass, which is conducive to reducing the energy consumption of the vehicle and the system on which it is mounted. In other specific embodiments that can be realized by the utility model, multiple groups of partitions 2 can also be arranged according to the specifications of the fuel tank body 1, and the arrangement of the partitions 2 can be adjusted according to the specific flow diversion requirements, while avoiding affecting the implementation of rotational molding.

[0041] It should be explained here that the polymer fuel tank 100 is a rotationally molded integral part, and the partition 2 is located in the inner cavity of the fuel tank body 1. The partition 2 is formed by encapsulating the metal bracket 3 during the rotational molding process. Therefore, the description that the partition 2 includes the metal bracket 3 and the metal bracket 3 and the fuel tank body 1 are rotationally molded into an integral structure is not contradictory. Rotational molding is common knowledge of those skilled in the art and will not be repeated here.

[0042] In this specific embodiment, the metal bracket 3 includes a main body 9, and the main body 9 includes a flat plate 13 and a curved panel 12. The flat plate 13 is connected to the curved panel 12, and a through hole 4 is provided on the flat plate 13. The protrusion of the curved panel 12 is arranged toward the center of the tank body 1. The main body 9 is provided with the flat plate 13 and the curved panel 12 at the same time, which not only further plays the role of wave prevention, flow diversion, and defoaming, but also enhances the structural strength of the metal bracket 3, ensures the structural strength of the partition 2, and thus improves the structural reliability of the polymer tank 100, especially the polymer tank 100 with larger specifications. The protrusion of the curved panel 12 is arranged toward the center of the tank body 1, which can enhance the impact resistance of the partition 2. Among them, the protrusion degree and specific parameters of the curved panel 12 can be adjusted according to the actual working conditions, and it is necessary to avoid the existence of dead corners in the rotational molding process to cause material accumulation.

[0043] In practical applications, there are multiple groups of flat panels 13 and curved panels 12 , which are spaced apart in the horizontal direction. The flat panels 13 and curved panels 12 can be integrated to enhance the structural strength of the metal bracket 3 .

[0044] Specifically, there are multiple through holes 4 on each plane plate 13, and the multiple through holes 4 are evenly distributed along the length direction of the plane plate 13, which improves the force uniformity of the plane plate 13. The aperture and arrangement of the through holes 4 can also be adjusted according to specific working conditions. On the premise of satisfying the passage of oil, the aperture, number and arrangement of the through holes 4 are reasonably set, which can also play a role in filtering and removing impurities, improve the performance of the polymer oil tank 100, and further ensure the normal operation of the hydraulic system.

[0045] More specifically, the metal bracket 3 further includes a first connection portion 10 and a second connection portion 11. The first connection portion 10 is disposed on the left and right sides of the main body 9. A bending plate 21 is disposed on one side of the first connection portion 10 away from the main body 9. The bending plate 21 extends in the convex direction of the curved panel 12. The bending plate 21 can further improve the degree of bonding between the metal bracket 3 and the polymer material during the rotational molding process, thereby improving the structural integrity of the metal bracket 3 and the tank body 1, and ensuring the structural strength of the polymer tank 100. The second connection portion 11 is disposed at the upper and lower ends of the main body 9. The flat plate 13 and the curved panel 12 are both connected to the second connection portion 11, and the second connection portion 11 extends in the convex direction of the curved panel 12; and both the first connection portion 10 and the second connection portion 11 can be fixed in the cavity of the rotational molding mold 200. When the polymer oil tank 100 is molded, the metal bracket 3 is used as an embedded part and is fixed in the cavity of the rotational molding mold 200 by using the first connecting part 10 and the second connecting part 11 to ensure the stability of the metal bracket 3 during the molding process and avoid the misalignment of the metal bracket 3 affecting the smooth molding of the polymer oil tank 100.

[0046] It should also be noted that the first connection part 10 is a hollow structure. During the rotational molding process, the polymer material enters the hollow part. After the molding is completed, the thickness of the polymer material entering the hollow part is often thicker, which can enhance the structural strength of the rotationally molded polymer tank 100. In addition, the hollow structure of the first connection part 10 can also improve the passing capacity, thereby further enhancing the wave-proof, diversion and defoaming effects of the partition 2. The first connection part 10 and the second connection part 11 are both provided with reinforcement holes 22, which are waist-shaped holes. During the rotational molding process, the first connection part 10 and the second connection part 11 can be embedded in the polymer material, and the polymer material enters the reinforcement hole 22 under the action of gravity, so that the first connection part 10 and the second connection part 11 are more firmly combined with the polymer material. While the metal bracket 3 is used to mold the partition 2 to achieve the wave-proof effect, the structural integrity of the metal bracket 3 and the tank body 1 is enhanced, and the structural strength of the polymer tank 100 is effectively improved.

[0047] In this specific embodiment, a connecting nut 14 is provided on the bending plate 21 of the first connecting part 10 and the second connecting part 11, and the threaded hole of the connecting nut 14 is a blind hole, and the first connecting part 10 and the second connecting part 11 can be fixed in the cavity of the rotational molding mold 200 by using the connecting nut 14. The positioning pin 19 in the molding mold 200 is threadedly connected with the connecting nut 14, which is convenient for fixing the metal bracket 3 and separating from the connecting nut 14 after molding. In practical applications, the fixing structure of the first connecting part 10 and the second connecting part 11 and the molding mold 200 can also be adjusted according to the molding requirements to meet the molding requirements and improve the molding quality of the polymer oil tank 100. In addition, multiple sets of connecting nuts 14 can be provided to improve the force uniformity of the metal bracket 3, ensure its stability during the molding process, and thus ensure the molding quality of the polymer oil tank 100.

[0048] In addition, the first connection portion 10 and the second connection portion 11 can be an integral structure with the main body 9, or can be a separate structure, welded into a whole, and can be adjusted according to actual production needs to meet different working conditions.

[0049] At the same time, guide plates 15 are provided at the four corners of the main body 9. The guide plates 15 are located between the first connecting portion 10 and the second connecting portion 11. The guide plates 15 extend from the main body 9 toward the center of the oil tank body 1 to guide the oil and avoid large fluctuations in the oil.

[0050] In addition, the side walls and the bottom wall of the fuel tank body 1 are provided with groove-shaped depressions to form reinforcing ribs 16 in the inner cavity of the fuel tank body 1 , thereby further enhancing the structural strength of the polymer fuel tank 100 and improving the adaptability of the polymer fuel tank 100 .

[0051] Embodiment 2

[0052] The present embodiment provides a molding mold 200 of the polymer oil tank in Embodiment 1, including an upper mold 17, a lower mold 18 and a positioning pin 19. The upper mold 17 and the lower mold 18 form a cavity matching the tank body 1. The metal bracket 3 can be detachably connected to the positioning pin 19 to fix the metal bracket 3 and separate from the metal bracket 3 after the polymer oil tank 100 is formed.

[0053] The molding die 200 of the polymer fuel tank of this embodiment uses the positioning pins 19 to fix the metal bracket 3 in the cavity surrounded by the upper mold 17 and the lower mold 18. The partition 2 is obtained after the metal bracket 3 is encapsulated with glue. After the rotational molding is completed, the positioning pins 19 are separated from the connecting threads to obtain a polymer fuel tank 100 with an integrated structure.

[0054] In this specific embodiment, the upper mold 17 is a split structure, and the upper mold 17 includes a slider 20 to form the fuel inlet 5 of the polymer fuel tank 100 .

[0055] It should be noted here that in actual applications, the spacing between the partition 2 formed after the metal bracket 3 is coated with rubber and the side wall of the tank body 1 is reasonably set to further ensure the strength of the polymer tank 100 and improve the working reliability of the tank. In this specific embodiment, the gap between the metal bracket 3 along the four sides (upper, lower, left and right sides) and the side wall of the cavity is (0.5-1.2) times the wall thickness of the finished polymer tank 100, and the thickness of the metal bracket 3 is (2.0-4.5) times the wall thickness of the finished polymer tank 100. The size ratio of the finished polymer tank 100 adopts a ratio of 0.8 / 3.0 to achieve internal partition and connection of the cavity; ensure the oil impact resistance and pressure resistance of the molecular tank 100, thereby enhancing the structural stability of the polymer tank 100, effectively preventing the deformation of the polymer tank 100, and improving its adaptability. In the actual production process, it can be adjusted according to the actual working conditions to meet different needs. It should also be noted here that, in actual applications, due to differences in rotational molding parameters, the first connection portion 10 and the second connection portion 11 of the metal bracket 3 may be completely wrapped by the polymer material, or may be partially wrapped by the polymer material, and adjustments are made according to specific molding conditions. However, in either case, during the rotational molding process, the polymer material flows into the reinforcement hole 22 under the action of gravity, so that the polymer material and the metal frame 3 are more firmly combined, thereby enhancing the overall structural strength of the metal frame 3 and the tank body 1 after integral molding.

[0056] Embodiment 3

[0057] This embodiment provides a hydraulic system, including the polymer oil tank 100 of the first embodiment. The polymer oil tank 100 has high structural strength and light weight, and can effectively ensure the stable operation of the hydraulic system.

[0058] The polymer fuel tank 100 of the utility model is an integrated rotational molding structure, a partition 2 is arranged in the inner cavity of the fuel tank body 1, the fuel tank body 1 is made of polymer material, and the partition 2 is made of a metal bracket 3 by rotational molding, which reduces the mass of the polymer fuel tank 100 and ensures the structural strength of the polymer fuel tank 100. The partition 2 has a through hole 4 to ensure that the inner cavity of the fuel tank body 1 is a complete and connected cavity, and the partition 2 acts as a wave-breaking plate to play a role in diversion and defoaming, further improving the performance of the polymer fuel tank 100.

[0059] Terminology explanation:

[0060] Roto-molding process: Roto-molding process is to first add the plastic raw materials into the mold, and then the mold is continuously rotated along two vertical axes and heated, so that the plastic raw materials in the mold are gradually and evenly coated, melted and adhered to the entire surface of the mold cavity under the action of gravity and heat energy, and formed into the required shape, and then cooled, shaped, demolded, and finally the finished product is obtained.

[0061] The present invention uses specific examples to illustrate the principle and implementation of the present invention. The above examples are only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A polymer fuel tank, comprising a fuel tank body, the fuel tank body being made of polymer material, the fuel tank body having a refueling port, a fuel suction port, a gas outlet and a fuel drain port, the refueling port, the fuel suction port, the gas outlet and the fuel drain port being all connected to the inner cavity of the fuel tank body; characterized in that: Also includes: A partition, wherein the partition is arranged in the inner cavity of the oil tank body, and the partition includes a metal bracket, and the metal bracket is rotationally molded into one piece with the oil tank body to form the partition; the number of the partitions is at least two groups; and the partition has a through hole to connect the cavities on both sides of the partition.

2. The polymer fuel tank according to claim 1, characterized in that: The metal bracket comprises a main body, the main body comprises a plane plate and a curved plate, the plane plate is connected to the curved plate, a through hole is arranged on the plane plate, and a protrusion of the curved plate is arranged toward the center of the oil tank body.

3. The polymer fuel tank according to claim 2, characterized in that: The number of the flat panels and the arc panels are both multiple groups, and the flat panels and the arc panels are arranged at intervals in the horizontal direction; There are multiple through holes on each of the planar plates, and the multiple through holes are evenly distributed along the length direction of the planar plate.

4. The polymer fuel tank according to claim 2, characterized in that: The metal bracket also includes a first connecting part and a second connecting part, the first connecting part is arranged on the left and right sides of the main body, and a bending plate is arranged on the side of the first connecting part away from the main body, and the bending plate extends toward the convex direction of the arc panel; the second connecting part is arranged at the upper and lower ends of the main body, the flat plate and the arc panel are both connected to the second connecting part, and the second connecting part extends toward the convex direction of the arc panel; the first connecting part and the second connecting part can be fixed in the cavity of the rotational molding mold.

5. The polymer oil tank according to claim 4, characterized in that: The first connection portion is a hollow structure, and both the first connection portion and the second connection portion are provided with reinforcement holes, and the reinforcement holes are waist-shaped holes.

6. The polymer oil tank according to claim 4, characterized in that: The bending plates of the first connecting part and the second connecting part are both provided with connecting nuts, the threaded holes of the connecting nuts are blind holes, and the first connecting part and the second connecting part can be fixed in the cavity of the rotational molding mold by using the connecting nuts.

7. The polymer oil tank according to claim 4, characterized in that: The four corners of the main body are each provided with a guide plate, the guide plate is located between the first connecting portion and the second connecting portion, and the guide plate extends from the main body toward the center direction of the oil tank body.

8. The polymer oil tank according to any one of claims 1 to 7, characterized in that: The side walls and the bottom wall of the oil tank body are both provided with groove-shaped depressions to form reinforcing ribs in the inner cavity of the oil tank body.

9. A molding die for a polymer fuel tank according to any one of claims 1 to 8, comprising an upper die, a lower die and a positioning pin, characterized in that: The upper mold and the lower mold enclose a cavity matching the oil tank body, and the metal bracket can be detachably connected to the positioning pin to fix the metal bracket and be separated from the metal bracket after the polymer oil tank is formed.

10. A hydraulic system, characterized in that: A polymer oil tank comprising any one of claims 1-8.

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