A high reliability electric heating pipe sealing structure and method

Abstract

A high-reliability electric heating pipe sealing structure and method, a lead rod is provided inside the electric heating pipe body, magnesium oxide powder is filled between the lead rod and the pipe body, an insulating sealing device is provided at the sealing of the electric heating pipe body, the insulating sealing device is divided into an upper opening, a middle channel, a lower channel, and a lower opening, the lead rod passes through the middle channel of the sealing device, a sealant is provided between the insulating sealing device and the electric heating pipe body, the upper outer diameter of the insulating sealing device is greater than the outer wall diameter of the electric heating pipe body sealing, the lower outer diameter is less than the inner wall diameter of the electric heating pipe body, the upper opening diameter gradually decreases toward the middle of the sealing device, the lower channel diameter gradually decreases toward the middle of the insulating sealing device, the lower opening is located below the lower channel, the lower opening diameter gradually decreases toward the lower channel, and the minimum diameter of the lower opening is equal to the maximum diameter of the lower channel. The present invention has the advantages of good bonding during the curing process of the sealant and improved insulation withstand voltage.

Description

Technical Field

[0001] The present invention relates to the technical field of electric heating, and in particular to a high-reliability electric heating tube sealing structure and method. Background Art

[0002] During the use of traditional electric heaters, the insulation resistance of the electric heating tube may decrease, resulting in damage to the electric heater or failure to use. Once the above situation occurs, it will cause serious safety and quality problems. An important requirement for electric heating tubes is that there should be no moisture inside the electric heating tubes. The general treatment method is to place the electric heating tube in an oven and heat it at 180-280℃ for several hours to more than 10 hours to fully remove the moisture adsorbed by the magnesium oxide powder in the electric heating tube. Then use RTV silicone or epoxy resin (hereinafter referred to as sealant) to seal the tube mouth.

[0003] like Figure 1 As shown, in order to increase the creepage distance, a sealing cap 3' is usually pressed into the mouth of the electric heating tube 1'. A guide rod 5' is provided at the mouth of the electric heating tube 1'. The guide rod 5' passes through the middle channel of the sealing cap 3'. A step portion 6' is provided on the outer wall of the sealing cap 3'. There is a gap between the step portion 6' and the inner wall of the mouth of the electric heating tube 1'. The pressed sealing cap 3' is required to be in full contact with the pre-injected sealant 4' and bonded into one body. There should be no gaps, pinholes, etc., otherwise it is easy to reduce the insulation resistance or electrical strength.

[0004] In actual production, if the amount of sealant 4' added during the packaging process is insufficient, a gap is likely to be generated between the sealing cap 3' and the sealant 4'; if the amount of sealant is just right, but because the bottom of the sealing cap 3' is flat, "air blocking" is likely to occur during the pressing process of the sealing cap 3', and a small amount of air will be "stifled" between the sealing cap 3' and the sealant 4'; if an excessive amount of sealant 4' is added, the sealant 4' will overflow from the mouth of the electric heating tube 1', causing contamination of the outer wall of the tube; even if the above factors do not exist, due to the shrinkage of the sealant 4' during the curing process (generally the shrinkage rate is between 2-5%), gaps and pinholes may also be generated at the interface between the sealant 4' and the sealing cap 3'. The above situations will cause the insulation withstand voltage to be unqualified, which greatly affects the service life and quality of the electric heater. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention provides an electric heating pipe sealing structure and method with reasonable structure, good sealant curing adhesion, no gaps and bubbles, and good insulation and sealing performance.

[0006] To achieve the above-mentioned purpose, the present invention provides a high-reliability electric heating pipe sealing structure on one hand, including an electric heating pipe body, a lead rod is arranged in the electric heating pipe body, magnesium oxide powder is filled between the lead rod and the electric heating pipe body, an insulating sealing device is arranged at the sealing part of the electric heating pipe body, the insulating sealing device includes a sealing body, an upper opening is arranged at the upper end of the sealing body, a lower opening is arranged at the lower end of the sealing body, a middle channel is arranged between the upper opening and the lower opening, a step portion is arranged on the outer side wall of the sealing body, the lead rod passes through the middle channel of the insulating sealing device, a gap is arranged between the middle channel and the lead rod, a sealant is arranged between the insulating sealing device and the electric heating pipe body, the electric heating pipe body is connected to the step portion of the sealing body, the diameter of the upper opening of the insulating sealing device gradually decreases toward the middle channel of the insulating sealing device, the diameter of the lower opening decreases toward the middle channel, and the smallest diameter of the lower opening is connected to the largest diameter of the middle channel,

[0007] In the above arrangement, since the diameter of the upper opening of the insulating sealing device gradually decreases toward the middle channel of the insulating sealing device, the upper opening is funnel-shaped. In this way, when the sealant is cured and shrunk, the sealant here shrinks downward, and no gap is generated between the contact surface of the sealing body and the sealant. At the same time, the diameter of the lower opening decreases toward the middle channel, so that the lower opening is trumpet-shaped. In addition, a middle channel is provided between the lower opening and the upper opening, and the opening of the middle channel is connected with the upper opening and the lower end opening, so that the sealant forms a tower-shaped structure, eliminating the gap between the sealant and the sealing body. The horizontal contact surface eliminates the air-tight condition, thereby greatly improving the reliability of insulation withstand voltage. At the same time, there is a gap between the middle channel and the lead rod, so that the sealant can smoothly rise to provide a channel, eliminating the gap and bubbles. The sealant is well bonded during the curing process and will not produce gaps and bubbles. In addition, due to the presence of the middle channel, the lower opening and the upper opening on the sealing body, excessive sealant will overflow upward from the middle channel, preventing excessive sealant from overflowing from the insulating sealing device and the inside of the electric heating tube body to cause pollution to the outer wall of the electric heating tube, and the electric heating tube has good insulation sealing performance.

[0008] Furthermore, the step portion of the sealing body includes a first step portion and a second step portion, the first step portion is connected to the inner wall of the electric heating tube body, and the second step portion is connected to the top surface of the electric heating tube body. The above arrangement makes it convenient to insert the sealing body into the electric heating tube body because the step portion is connected to the inner wall and the top surface of the electric heating tube body.

[0009] Furthermore, the middle channel includes a first middle channel and a lower channel in sequence from the upper end to the lower end of the insulating sealing device. The upper end of the first middle channel is connected to the lower end of the upper opening, the lower end of the first middle channel is connected to the upper end of the lower channel, and the lower end of the lower channel is connected to the upper end of the lower opening. The above arrangement divides the middle channel into two parts, and the sealant entering the lower channel is buffered by the middle channel to prevent excessive sealant from entering the sealing body.

[0010] Furthermore, the depth of the upper opening of the insulating sealing device is smaller than the depth of the lower channel. The above arrangement increases the depth of the lower channel, so that more sealant enters the lower channel and the middle channel, and a small amount enters the upper opening, thereby preventing too much sealant from entering the upper opening.

[0011] Furthermore, the diameter of the lower channel gradually increases from the middle of the insulating sealing device toward the lower opening channel. With the above arrangement, since the opening area of ​​the lower end face of the lower channel is large and thus the pressure is high, it is convenient for the sealant to enter the middle channel from the lower opening.

[0012] Furthermore, the middle channel is a cylindrical structure. With the above arrangement, when the sealant passes through the middle channel, the guide rod and the insulating sealing device are well bonded, so that the insulating sealing device is tightly combined with the tube body.

[0013] Another aspect of the present invention provides a high-reliability electric heating tube sealing method, comprising the following steps:

[0014] 1) Fill the body of the electric heating tube with magnesium oxide powder;

[0015] 2) Dig out d mm of magnesium oxide powder at the end of the electric heating tube;

[0016] 3) Inject the sealant into the body of the electric heating tube in advance, and make sure that the injected sealant is d / 8mm away from the tube opening of the electric heating tube;

[0017] 4) Press the insulating sealing device into the sealant, and the sealant flows out from the gap between the middle channel and the lead rod toward the upper opening to fill the gap between the sealing body and the lead rod.

[0018] In the above method, the sealant is first injected into the body of the electric heating tube, and the injected sealant is kept at a certain distance from the tube mouth, and then the insulating sealing device is pressed into the sealant, so that the sealant flows out from the gap between the middle channel and the lead rod and fills the gap between the sealing body and the lead rod, so that the sealant smoothly rises to provide a channel, eliminates gaps and bubbles, and the sealant is well bonded during the curing process without generating gaps and bubbles. At the same time, since the diameter of the upper opening of the insulating sealing device gradually decreases toward the middle channel of the insulating sealing device, the upper opening is funnel-shaped. In this way, when the sealant is cured and shrunk, the sealant here shrinks downward, and no gap is generated on the contact surface between the sealing body and the sealant. The diameter of the lower opening decreases toward the middle channel, so that the lower opening is trumpet-shaped. In addition, a middle channel is provided between the lower opening and the upper opening, and the opening of the middle channel is connected with the upper opening and the lower end opening, so that the sealant forms a tower-shaped structure, eliminating the horizontal contact surface between the sealant and the sealing body, eliminating the air-tight condition, thereby greatly improving the reliability of insulation withstand voltage. At the same time, there is a gap between the middle channel and the lead rod. In addition, due to the existence of the middle channel, the lower opening and the upper opening on the sealing body, excessive sealant will overflow from the middle channel, preventing excessive sealant from overflowing from the insulating sealing port device and the inside of the electric heating tube body to cause pollution of the outer wall of the electric heating tube, and the electric heating tube has good insulation sealing performance.

[0019] Furthermore, the above method also includes: step 5) if the sealant does not fill up the upper opening, then fill up the upper opening with the sealant, and fill up the upper opening by post-filling, thereby ensuring the reliability of filling up the upper opening.

[0020] Furthermore, d is 5-13 mm, and the above setting is convenient for operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the sealing structure of the electric heating pipe in the prior art.

[0022] Figure 2 Schematic diagram of the structure of the electric heating tube sealing structure according to an embodiment of the present invention.

[0023] Figure 3 It is a schematic diagram of the first implementation structure of the insulating sealing device of an embodiment of the present invention.

[0024] Figure 4 It is a schematic diagram of the second implementation structure of the insulating sealing device of an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] Example 1

[0027] See also Figure 2-Figure 3 On the one hand, the present invention provides a high-reliability electric heating pipe sealing structure, including an electric heating pipe body 1, a guide rod 5 is arranged in the electric heating pipe body 1, and magnesium oxide powder 2 is filled between the guide rod 5 and the electric heating pipe body 1, and an insulating sealing device 3 is arranged at the sealing end of the electric heating pipe body 1, and the insulating sealing device 3 includes a sealing body, an upper opening 31 is arranged at the upper end of the sealing body, a lower opening 33 is arranged at the lower end of the sealing body, a through middle channel 32 is arranged between the upper opening 31 and the lower opening 33, and a step is arranged on the outer wall of the sealing body The guide rod 5 passes through the middle channel 32 of the insulating sealing device 3, and there is a gap between the middle channel 32 and the guide rod 5. A sealant 4 is provided between the insulating sealing device 3 and the electric heating pipe body 1. The electric heating pipe body 1 is connected to the step portion 34 of the sealing body. The diameter of the upper opening 31 of the insulating sealing device 3 gradually decreases toward the middle channel 32 of the insulating sealing device 3, and the diameter of the lower opening 33 decreases toward the middle channel 32. The smallest diameter of the lower opening 33 is connected to the largest diameter of the middle channel 32.

[0028] In the above arrangement, since the diameter of the upper opening 31 of the insulating sealing device 3 gradually decreases toward the middle channel 32 of the insulating sealing device 3, the upper opening 31 is funnel-shaped. In this way, when the sealant 4 solidifies and shrinks, the sealant here shrinks downward, and no gap is generated between the contact surface of the sealing body and the sealant 4. At the same time, the diameter of the lower opening 33 decreases toward the middle channel 32, so that the lower opening 33 is trumpet-shaped. In addition, a middle channel 32 is provided between the lower opening 33 and the upper opening 31, and the opening of the middle channel 32 is connected with the upper opening and the lower end opening, so that the sealant forms a tower-shaped structure, eliminating the sealant 4 and the sealant. The horizontal contact surface between the main bodies eliminates the airtight condition, thereby greatly improving the reliability of insulation withstand voltage. At the same time, there is a gap between the middle channel 32 and the lead rod 5, so that the sealant 4 can smoothly rise to provide a channel, eliminating gaps and bubbles. The sealant 4 is well bonded during the curing process and will not produce gaps and bubbles. In addition, due to the presence of the middle channel 32, the lower opening 33 and the upper opening 31 on the sealing body, excessive sealant 4 will overflow from the middle channel 32, preventing excessive sealant 4 from overflowing from between the insulating sealing device 3 and the inside of the electric heating tube body 1 to cause pollution to the outer wall of the electric heating tube, and the electric heating tube has good insulation sealing performance.

[0029] The step portion 34 of the sealing body includes a first step portion 341 and a second step portion 342. The first step portion 341 is connected to the inner wall of the electric heating tube body 1, and the second step portion 342 is connected to the top surface of the electric heating tube body 1. The above arrangement makes it convenient to insert the sealing body into the electric heating tube body 1 because the step portion 34 is connected to the inner wall and the top surface of the electric heating tube body 1.

[0030] The depth of the upper opening 31 of the insulating sealing device 3 is smaller than the depth of the lower channel 322. The above arrangement increases the depth of the lower channel 322, so that more sealant 4 enters the lower channel 322 and the middle channel 32, and a small amount enters the upper opening 31, thereby preventing too much sealant 4 from entering the upper opening 31.

[0031] The diameter of the lower channel 322 gradually increases from the middle of the insulating sealing device 3 to the lower opening 33. The above arrangement allows the sealant 4 to enter the middle channel 32 from the lower opening 33 due to the large opening area of ​​the lower end surface of the lower channel 322, thereby increasing the pressure.

[0032] The middle channel 32 is a cylindrical structure. With the above arrangement, due to the larger diameter of the middle channel 32 , the sealant 4 entering the lower channel 322 transitions through the middle channel 32 , slowing down the flow rate into the upper opening 31 , and preventing too much sealant 4 from quickly entering the upper opening 31 .

[0033] Example 2

[0034] like Figure 3-4 As shown, the difference between Example 2 and Example 1 is that the structure of the middle channel is different, and the other structures are the same.

[0035] In this embodiment, the middle channel 32 includes a first middle channel 321 and a lower channel 322 along the upper end to the lower end of the insulating sealing device 3. The upper end of the first middle channel 321 is connected to the lower end of the upper opening 31, the lower end of the first middle channel 321 is connected to the upper end of the lower channel 322, and the lower end of the lower channel 322 is connected to the upper end of the lower opening 33. The above arrangement divides the middle channel 32 into two parts. When the sealant 4 entering the lower channel 322 passes through the middle channel 32, the guide rod and the insulating sealing device are well bonded through the sealant 4, so that the insulating sealing device is tightly combined with the tube body.

[0036] Example 3

[0037] The present invention provides a sealing method for a high-reliability electric heating pipe. The sealing structure of the high-reliability electric heating pipe is shown in Example 1 and Example 2. The sealing method comprises the following steps:

[0038] 1) Filling magnesium oxide powder 2 into the body 1 of the electric heating tube;

[0039] 2) Dig out d millimeters of magnesium oxide powder 2 at the end of the electric heating tube body 1;

[0040] 3) Inject the sealant 4 into the electric heating tube body 1 in advance, and make the injected sealant 4 be d / 8mm away from the tube opening of the electric heating tube body 1; in this embodiment, d is 5-13mm, and the above setting is convenient for operation;

[0041] 4) The insulating sealing device 3 is pressed into the sealant 4 , and the sealant 4 flows out from the gap between the middle channel 32 and the lead rod 5 toward the upper opening 31 to fill the gap between the sealing body and the lead rod 5 .

[0042] In the above method, the sealant 4 is first injected into the tube body 1 of the electric heating tube, and the injected sealant 4 is kept at a certain distance from the tube mouth, and then the insulating sealing device 3 is pressed into the sealant 4, so that the sealant 4 flows out from the gap between the middle channel 32 and the lead rod 5 and fills the gap between the sealing body and the lead rod 5, so that the sealant 4 smoothly rises to provide a channel, eliminates the gap and bubbles, and the sealant 4 is well bonded during the curing process without generating gaps and bubbles. At the same time, since the diameter of the upper opening 31 of the insulating sealing device 3 gradually decreases toward the middle channel 32 of the insulating sealing device 3, the upper opening 31 is funnel-shaped. In this way, when the sealant 4 is cured and shrunk, the sealant 4 here shrinks downward, and no gap is generated on the contact surface between the sealing body and the sealant 4. At the same time, the lower opening 33 The diameter decreases toward the middle channel 32, so that the lower opening 33 is trumpet-shaped. In addition, a middle channel 32 is provided between the lower opening 33 and the upper opening 31, and the opening of the middle channel 32 is connected with the upper opening and the lower end opening, so that the sealant 4 forms a tower-shaped structure, eliminating the horizontal contact surface between the sealant 4 and the sealing body, eliminating the air-tight condition, thereby greatly improving the reliability of insulation withstand voltage. At the same time, there is a gap between the middle channel 32 and the lead rod 5. In addition, due to the presence of the middle channel 32, the lower opening 33 and the upper opening 31 on the sealing body, excessive sealant 4 will overflow from the middle channel 32, preventing excessive sealant 4 from overflowing from between the insulating sealing device 3 and the inside of the electric heating tube body 1 to cause pollution of the outer wall of the electric heating tube, and the electric heating tube has good insulation sealing performance.

[0043] The above method further includes: step 5) if the sealant 4 does not fill up the upper opening, then fill up the upper opening with the sealant 4, and fill up the upper opening by post-filling, thereby ensuring the reliability of filling up the upper opening.

Claims

1. A high reliability electric heating pipe sealing structure, characterized in that: It comprises an electric heating tube body, a lead rod is arranged in the electric heating tube body, magnesium oxide powder is filled between the lead rod and the electric heating tube body, an insulating sealing device is arranged at the sealing of the electric heating tube body, the insulating sealing device comprises a sealing body, an upper opening is arranged at the upper end of the sealing body, a lower opening is arranged at the lower end of the sealing body, a through middle channel is arranged between the upper opening and the lower opening, a gap exists between the middle channel and the lead rod, a step portion is arranged on the outer side wall of the sealing body, the lead rod passes through the middle channel of the insulating sealing device, a sealant is arranged between the insulating sealing device and the electric heating tube body, the electric heating tube body is connected to the step portion of the sealing body, the diameter of the upper opening of the insulating sealing device gradually decreases toward the middle channel of the insulating sealing device, the diameter of the lower opening decreases toward the middle channel, and the smallest diameter of the lower opening is connected to the largest part of the middle channel; The step portion of the sealing body includes a first step portion and a second step portion, the first step portion is connected to the inner wall of the electric heating tube body, and the second step portion is connected to the top surface of the electric heating tube body; The middle channel includes a first middle channel and a lower channel from the upper end to the lower end of the insulating sealing device, the upper end of the first middle channel is connected to the lower end of the upper opening, the lower end of the first middle channel is connected to the upper end of the lower channel, and the lower end of the lower channel is connected to the upper end of the lower opening.

2. The high reliability electric heating pipe sealing structure according to claim 1, characterized in that: The depth of the upper opening of the insulating sealing device is smaller than the depth of the lower channel.

3. The high reliability electric heating pipe sealing structure according to claim 1, characterized in that: The diameter of the lower channel gradually increases from the middle of the insulating sealing device toward the lower opening channel.

4. The high reliability electric heating pipe sealing structure according to claim 1, characterized in that: The middle channel is a cylindrical structure.

5. A sealing method for a high-reliability electric heating pipe sealing structure according to any one of claims 1 to 4, characterized in that: The following steps are involved: 1) Fill the body of the electric heating tube with magnesium oxide powder; 2) Dig out d mm of magnesium oxide powder at the end of the electric heating tube; 3) Inject the sealant into the body of the electric heating tube in advance, and make sure that the injected sealant is d / 8mm away from the tube opening of the electric heating tube; 4) Press the insulating sealing device into the sealant, and the sealant flows out from the gap between the middle channel and the lead rod toward the upper opening to fill the gap between the sealing body and the lead rod.

6. The sealing method according to claim 5, characterized in that: After step 4), the method further includes: step 5) if the sealant does not fill up the upper opening, filling the upper opening with the sealant.

7. The sealing method according to claim 5, characterized in that: d is 5~13mm.

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