A rubber air intake tube and a method of making the same

Abstract

The application provides a rubber air inlet pipe and a preparation method thereof, and belongs to the technical field of rubber pipe material preparation. The application adopts the hardness feature of 70±5(A) of the vulcanized A mixing rubber, effectively realizes easy assembly of the rubber pipe, and meets the air tightness performance; the hardness feature of 80±5(A) of the vulcanized B mixing rubber is adopted, and the application in the middle section of the pipe body effectively realizes the negative pressure resistance performance condition; the vulcanized rubber performance meets the A mixing rubber and the B mixing rubber in table 1, and the high and low temperature oil gas resistance effect of the whole air inlet pipe is ensured. The rubber air inlet pipe prepared by vulcanization of the A mixing rubber and the B mixing rubber: after (170℃*168h) heat air aging, there is no aging cracking phenomenon on the surface of the product; after (‑35℃*5h) low temperature resistance test, there is no cracking phenomenon on the surface of the product; after (150℃*168h) standard lubricating oil liquid test, the air tightness test is normal at the time of‑13kPa~250kPa gauge pressure, and the design requirement is met.

Description

Technical Field

[0001] This invention relates to the field of rubber pipe manufacturing technology, and in particular to a rubber air inlet pipe and its manufacturing method. Background Technology

[0002] High-temperature resistant rubber intake pipes are intermediate connecting components in the engine's air supply system and intake piping. They are required to maintain airtightness, preventing oil and gas leakage and collapse under positive and negative pressures ranging from -10 to 200 kPa in environments ranging from -30°C to 150°C. Currently, due to the lack of standardized design specifications for the interfaces of various auxiliary pipes in turbochargers and air filters produced by different manufacturers, variations exist in pipe size, length, negative pressure resistance, and airtightness requirements. During high-power engine operation, the increased intake volume due to turbocharger operation, coupled with the air filter's filtration function which somewhat obstructs airflow, creates time-varying, pulsating negative pressure in the rubber hoses connecting intermediate transition pipes. Because the entire hose assembly vibrates during engine operation and accumulates heat, ordinary hoses are prone to collapse due to negative pressure, resulting in engine shutdown due to oxygen deficiency. Summary of the Invention

[0003] To address the above problems, the present invention aims to provide a rubber air inlet pipe and its preparation method. The rubber air inlet pipe prepared by the present invention can achieve the goals of good air tightness, strong negative pressure resistance, and reliable and stable use.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] This invention provides a method for preparing a rubber air inlet pipe, comprising the following steps: applying compound A to both ends of the pipe body, applying compound B to the middle section of the pipe body, and tightly splicing the compound A and compound B together, and co-curing in a mold cavity to obtain the rubber air inlet pipe; the vulcanized rubbers corresponding to the compound A and compound B meet the requirements of Table 1; the compound A and compound B use the same raw rubber;

[0006] Table 1 Technical Specifications of Methyl Vulcanizate and Ethyl Vulcanizate

[0007]

[0008]

[0009] Preferably, the co-vulcanization temperature is 150–200°C; the time is 5–30 min; and the vulcanization clamping pressure is 0.5–3 MPa.

[0010] Preferably, the co-vulcanization temperature is 170–190°C; the time is 10–20 min; and the vulcanization clamping pressure is 1–2.5 MPa.

[0011] Preferably, the compound A and compound B are ACM compound, AEM compound, FKM compound, MQ compound, or FVMQ compound.

[0012] Preferably, when the compound A and compound B are ACM compounds, the formulation of ACM compound A is shown in Table 2; and the formulation of ACM compound B is shown in Table 3.

[0013] Table 2 ACM Nail Compound Formulation Table

[0014]

[0015]

[0016] Table 3 ACM Ethylene Compound Formulation Table

[0017]

[0018] Preferably, the ACM raw rubber is AR72F.

[0019] The present invention provides a rubber air inlet pipe prepared by the preparation method described above, wherein the two ends are made of vulcanizate methyl ester and the middle section is made of vulcanizate ethyl ester; the vulcanizate methyl ester and the vulcanizate ethyl ester are tightly connected; the vulcanizate methyl ester and the vulcanizate ethyl ester meet the performance requirements in Table 1.

[0020] This invention provides a method for preparing a rubber air inlet pipe, comprising the following steps: applying compound A to both ends of the pipe body, applying compound B to the middle section of the pipe body, and tightly splicing the compound A and compound B together, and co-curing in a mold cavity to obtain the rubber air inlet pipe; the vulcanized rubbers corresponding to the compound A and compound B meet the requirements of Table 1; the compound A and compound B use the same raw rubber.

[0021] This invention utilizes compound A, which, after vulcanization, achieves a Shore hardness of 70±5 (A), effectively ensuring easy assembly of the hose and meeting airtightness requirements. Compound B, after vulcanization, achieves a Shore hardness of 80±5 (A), which, when applied to the middle section of the hose, effectively meets negative pressure resistance requirements. By employing vulcanized rubbers that meet the performance requirements of compound A and compound B in Table 1, the overall high and low temperature oil and gas resistance of the intake pipe is ensured.

[0022] The A compound and B compound of the present invention use the same raw rubber to ensure that the vulcanization speed of the two compounds is basically the same under the same vulcanization conditions, and the error value of the scorch T(10) of the two compounds is less than 5%; the error value of the positive vulcanization time T(90) of the two compounds is less than 8%.

[0023] The results of the embodiments show that the rubber air inlet pipe made by vulcanizing the compound of rubber A and B of the present invention exhibits no aging cracking on the product surface after heat aging (170℃×168h); no cracking on the product surface after low temperature resistance test (-35℃×5h); and normal air tightness test at gauge pressures of -13kPa to 250kPa after standard lubricating oil resistance test (150℃×168h), meeting the design requirements. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the rubber air inlet pipe of the present invention;

[0025] Figure 2 This is a plan view of the rubber air inlet pipe in Embodiment 1 of the present invention. Detailed Implementation

[0026] This invention provides a method for preparing a rubber air inlet pipe, comprising the following steps: applying compound A to both ends of the pipe body, applying compound B to the middle section of the pipe body, and tightly splicing the compound A and compound B together, and co-curing in a mold cavity to obtain the rubber air inlet pipe; the vulcanized rubbers corresponding to the compound A and compound B meet the requirements of Table 1; the compound A and compound B use the same raw rubber;

[0027] Table 1 Technical Specifications of Methyl Vulcanizate and Ethyl Vulcanizate

[0028]

[0029]

[0030] This invention does not impose specific limitations on the formulations of compound A and compound B, as long as their vulcanized rubber meets the requirements of Table 1. Specifically, compound A and compound B can be ACM compound, AEM compound, FKM compound, MQ compound, or FVMQ compound. In this invention, when testing the performance of the vulcanized rubber of compound A and compound B, the vulcanization conditions are the same as those described for co-vulcanization.

[0031] In Table 1, the standard lubricating oil refers to the national standard lubricating oil. With the promotion of the National III and National IV environmental protection requirements, CF and CH grades have become the mainstream. This invention refers to "Lubricating Oil CH-4".

[0032] This invention utilizes compound A, which, after vulcanization, achieves a Shore hardness of 70±5 (A), effectively ensuring easy assembly of the hose and meeting airtightness requirements. Compound B, after vulcanization, achieves a Shore hardness of 80±5 (A), which, when applied to the middle section of the hose, effectively meets negative pressure resistance requirements. By employing vulcanized rubbers that meet the performance requirements of compound A and compound B in Table 1, the overall high and low temperature oil and gas resistance of the intake pipe is ensured.

[0033] In an embodiment of the present invention, when the compound A and compound B are ACM compounds, the formulation of ACM compound A is shown in Table 2; the formulation of ACM compound B is shown in Table 3.

[0034] Table 2 ACM Nail Compound Formulation Table

[0035]

[0036]

[0037] Table 3 ACM Ethylene Compound Formulation Table

[0038]

[0039] In this invention, the ACM raw rubber described in Tables 2 and 3 is preferably AR72F.

[0040] This invention does not have special requirements for the preparation methods of the A and B compound rubbers; any preparation method well known in the art can be used. In the embodiments of this invention, the preferred preparation method of the ACM compound rubber includes the following steps: weighing the quota according to the quantities in Table 2, placing the main material and vulcanizing agent separately; starting the internal mixer to enter the production state, putting the quota of main material into the mixing chamber, raising the mixing temperature to 100°C, and mixing for 4 minutes; raising the mixing temperature to 130°C and continuing to mix for 9 minutes before discharging; allowing the rubber compound to cool to below 50°C, transferring it to the open mill to prepare for vulcanization; starting the open mill and putting in the mixed rubber compound, adjusting the roller gap to make the rubber sheet thickness 3-5 mm, adding the vulcanizing agent for thin-passing (note that the vulcanizing agent must be dispersed and sprinkled in), and making triangular wraps three to five times; after the vulcanizing agent is evenly dispersed and mixed in the compound rubber, producing rubber sheets of the required thickness for cooling and use, thus obtaining the ACM compound rubber.

[0041] ACM ethyl compound was produced using the same method described above.

[0042] In this invention, the co-vulcanization temperature is preferably 150–200°C, more preferably 160–190°C, and even more preferably 170–180°C; the co-vulcanization time is preferably 5–30 min, more preferably 10–20 min, and even more preferably 13–18 min; the vulcanization clamping pressure is preferably 0.5–3 MPa, more preferably 1–2.5 MPa, and even more preferably 2–2.5 MPa.

[0043] The present invention uses the same raw rubber for both compound A and compound B, ensuring that the vulcanization speeds of the two compounds are essentially the same under the same vulcanization conditions. During the co-vulcanization process, the two compounds soften and interweave at their contact surfaces within the mold cavity, allowing rubber molecules to interpenetrate and form organic bonds, thereby achieving vulcanization and shaping, resulting in a high-quality product with stable performance, and the product manufacturing process is easy to control.

[0044] The present invention provides a rubber air inlet pipe prepared by the preparation method described above, wherein the two ends are made of vulcanizate methyl ester and the middle section is made of vulcanizate ethyl ester; the vulcanizate methyl ester and the vulcanizate ethyl ester are tightly connected; the vulcanizate methyl ester and the vulcanizate ethyl ester meet the performance requirements in Table 1.

[0045] The rubber air inlet pipe of this invention, made by vulcanizing a mixture of rubber compounds A and B, shows no signs of aging or cracking on its surface after heat aging (170℃×168h); no signs of cracking on its surface after low-temperature testing (-35℃×5h); and normal air tightness at gauge pressures from -13kPa to 250kPa after standard lubricating oil testing (150℃×168h), meeting design requirements.

[0046] The following detailed description of the rubber air inlet pipe and its preparation method provided by the present invention, with reference to the embodiments, should not be construed as limiting the scope of protection of the present invention.

[0047] The preparation process of the ACM compound A and B used in the following examples and comparative examples is as follows:

[0048] Weigh the quota according to the quantities in Table 2, and place the main materials and vulcanizing agents separately; start the internal mixer to enter the production state, put the quota of main materials into the mixing chamber, raise the mixing temperature to 100℃, and mix for 4 minutes; raise the mixing temperature to 130℃ and continue mixing for 9 minutes before discharging; let the rubber compound cool to below 50℃, and transfer it to the open mill to prepare for vulcanization; start the open mill and put in the mixed rubber compound, adjust the roller gap to make the rubber sheet thickness 3-5mm, add the vulcanizing agent and pass it through thinly (note that the vulcanizing agent must be sprinkled in dispersedly), and make triangular wraps three to five times; after the vulcanizing agent is evenly dispersed and mixed in the rubber compound, produce rubber sheets of the required thickness and cool them for use to obtain ACM compound.

[0049] ACM ethyl compound was produced using the same method described above, as shown in Table 3.

[0050] The above-mentioned ACM compound A and B were vulcanized for 18 minutes at a vulcanization temperature of 180°C and a vulcanization clamping pressure of 2.5 MPa. The vulcanized rubber was then tested, and the various physical properties are shown in Table 4. The results fully meet the required parameter values.

[0051] Table 4. Properties of Compound A and Compound B used in the Examples and Comparative Examples after vulcanization.

[0052]

[0053] Example 1

[0054] ACM Compound A and ACM Compound B are used for positioning and splicing to manufacture hoses (such as...). Figure 1 As shown), the hose model is AF110-260-7, and the dimensions are as follows. Figure 2 As shown, the unit is mm; two types of compound rubber (ACM) A and B are used. Compound rubber A is used at both ends of the hose, and compound rubber B is used in the middle section of the hose. The two compounds are passed together through a special mold, vulcanized for 18 minutes, at a vulcanization temperature of 180℃, and with a vulcanization clamping pressure of 2.5MPa, to form the hose.

[0055] The test results are shown in Table 5:

[0056] Air tightness: When the gauge pressure of compressed air at room temperature is 250 kPa, there is no air leakage at either end of the hose.

[0057] Negative pressure performance: During the room temperature vacuum test, no denting or collapse was observed in the hose under a vacuum gauge pressure of -15 kPa.

[0058] Conclusion: Both airtightness and negative pressure performance meet the requirements.

[0059] Table 5 Performance of the hose in Example 1

[0060]

[0061] Comparative Example 1

[0062] All hoses are made of ACM nail compound:

[0063] ACM compound rubber is used to form rubber tubes by vulcanizing and shaping the compound rubber in the mold cavity using a special mold, with a vulcanization time of 18 minutes, a vulcanization temperature of 180℃, and a vulcanization clamping pressure of 2.5MPa.

[0064] Experimental results:

[0065] Air tightness: No air leakage is observed when the gauge pressure of compressed air is 220 kPa at room temperature.

[0066] Negative pressure performance: When the air gauge pressure is -5 kPa at room temperature, obvious suction and indentation occur.

[0067] Conclusion: Does not meet the requirements for negative pressure performance.

[0068] Comparative Example 2

[0069] All hoses are made of ACM ethylene compound rubber.

[0070] ACM ethyl compound is used to form a rubber tube by vulcanization and shaping in a mold cavity using a special mold, with a vulcanization time of 18 minutes, a vulcanization temperature of 180℃, and a vulcanization clamping pressure of 2.5MPa.

[0071] Experimental results:

[0072] Air tightness: At room temperature, when the gauge pressure of compressed air is 150 kPa, air leakage occurs at both ends of the hose due to its rigidity.

[0073] Negative pressure performance: The airtightness of the two joints of the hose is poor at room temperature, and it stops after the air gauge pressure drops to -8kPa.

[0074] Conclusion: Does not meet the requirements for airtightness and negative pressure performance.

[0075] Comparative Example 3

[0076] The tubing is made by positioning and splicing two types of ACM compound A and ACM compound B:

[0077] Two types of ACM compound, A1 and A2, are used. Compound A2 is used at both ends of the hose, while compound A2 is used in the middle section of the hose. The two compounds are passed together through a special mold and vulcanized in the mold cavity for 18 minutes at 180°C and 2.5 MPa to form the hose.

[0078] Experimental results:

[0079] Air tightness: At room temperature, when the gauge pressure of compressed air is 150 kPa, air leakage occurs at both ends of the hose due to its rigidity.

[0080] Negative pressure performance:

[0081] 1. Due to the high hardness of the rubber compound, the airtightness of the two joints of the rubber hose at room temperature cannot meet the standard.

[0082] 2. During the vacuuming and collapse test, a severe dent appeared in the middle of the hose when the air gauge pressure was -8 kPa.

[0083] Conclusion: Neither airtightness nor negative pressure meets the specified requirements.

[0084] As can be seen from the above examples and comparative examples, the hoses made with a single rubber compound using existing manufacturing methods (such as Comparative Example 1 and Comparative Example 2) have no problems in terms of manufacturing process, but their performance in terms of airtightness and resistance to positive and negative pressure is clearly unsatisfactory. The hoses obtained by the method of this invention are not only easy to control throughout the manufacturing process but also have stable quality, making it a very ideal manufacturing method. The overall performance of the hoses also meets the requirements, indicating that the method of this invention truly solves all the problems of the prior art. Furthermore, this invention selects high and low temperature resistant rubbers such as ACM as the manufacturing raw materials, ensuring that the hoses fully meet the working performance requirements of long-term high and low temperature standard lubricating oils.

[0085] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a rubber air inlet pipe, characterized in that, The process includes the following steps: applying compound A to both ends of the pipe body and compound B to the middle section of the pipe body, tightly bonding the compound A and compound B together, and co-curing them in a mold cavity to obtain the rubber air inlet pipe; the vulcanized rubbers corresponding to the compound A and compound B meet the requirements of Table 1; the compound A and compound B use the same raw rubber; Table 1 Technical Specifications of Methyl Vulcanizate and Ethyl Vulcanizate The compound A and compound B are ACM compounds. The formulation of ACM compound A is shown in Table 2; the formulation of ACM compound B is shown in Table 3. Table 2 ACM Compound Formulation Table Table 3 ACM Ethylene Compound Formulation Table 。 2. The preparation method according to claim 1, characterized in that, The co-vulcanization temperature is 150~200℃; the time is 5~30min; and the vulcanization clamping pressure is 0.5~3MPa.

3. The preparation method according to claim 2, characterized in that, The co-vulcanization temperature is 170~190℃; the time is 10~20min; and the vulcanization clamping pressure is 1~2.5MPa.

4. The preparation method according to claim 1, characterized in that, The ACM raw rubber is AR72F.

5. The rubber air inlet pipe prepared by the preparation method according to any one of claims 1 to 4, characterized in that, The two ends are made of vulcanizate methyl ester, and the middle section is made of vulcanizate ethyl ester; the vulcanizate methyl ester and vulcanizate ethyl ester are tightly connected; the vulcanizate methyl ester and vulcanizate ethyl ester meet the performance requirements in Table 1.

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