Welding structure and welding method of a pressure sensor oil filling hole

Abstract

This invention relates to the field of pressure sensor technology, and discloses a welding structure and welding method for an oil filling hole in a pressure sensor. The structure includes: a housing and a pin; an oil filling hole is provided inside the housing, with its two ends communicating with an oil storage area and an inner chamber, respectively; a boss is provided between the oil storage area and the oil filling hole; the pin is inserted into the oil filling hole, and the pin head connects to the boss; the pin is electrically connected to the upper electrode, and the housing is electrically connected to the lower electrode. This invention improves upon the previous steel ball sealing method by using a pin seal, which not only makes assembly more convenient but also changes the welding joint from point-to-surface contact to surface-to-surface contact, improving the fault tolerance during the sealing welding process; secondly, an oil storage area is provided outside the oil filling hole, ensuring the entire welding area is always immersed in oil before and after welding, avoiding oil loss in the inner chamber during the welding process; a welding ring groove is provided around the boss, which allows for rapid accumulation of welding heat during welding, promoting rapid melting of the boss.

Description

Technical Field

[0001] This invention relates to the field of pressure sensor technology, and in particular to a welding structure and welding method for an oil filling hole in a pressure sensor. Background Technology

[0002] Pressure sensors are one of the main sensing components in aircraft and aerospace vehicles. Pressure sensors require filling with oil and then sealing and welding. This process is crucial for ensuring sufficient and leak-free oil inside the pressure sensor, directly affecting its performance and lifespan, and is one of the core technologies in pressure sensor manufacturing. The pressure sensor is filled with a sufficient amount of oil inside its stainless steel housing to ensure uniform pressure within the cavity. After filling, the oil filling hole must be sealed and welded to ensure that the stainless steel cavity is always filled with oil and isolated from the outside environment.

[0003] Currently, pressure sensors use steel balls as plugs to seal the oil filling holes. The welding is done directly using resistance welding, with spherical steel balls as the sealing material. During the welding assembly process, the steel ball is placed at the opening of the hole. The upper and lower electrodes of the resistance welding machine act directly on the stainless steel shell and the steel ball, respectively. During welding, the welding current passes through the upper electrode, the steel ball, the shell, and the lower electrode. Heat is generated under the contact resistance between the steel ball and the shell, causing the metal at the contact point to heat up and melt. Under the action of electrode force, a welded connection is formed. The following problems exist with this sealing method: First, the assembly and resistance welding of steel balls after filling with oil can easily lead to oil loss during the operation, resulting in insufficient oil filling in the internal cavity of some pressure sensors after welding. Second, due to the small size of the steel balls during assembly, the presence of oil at the welding interface during welding makes it difficult for the steel balls to be aligned with the orifice opening. Under the welding pressure, the steel balls become misaligned, resulting in incomplete sealing of the orifice opening. Third, due to the influence of the welding structure and welding method during resistance welding, the base material on the orifice side melts less and deforms less, while the steel balls melt more and deform more, making the steel balls prone to cracking and resulting in incomplete sealing at the weld. Summary of the Invention

[0004] This invention provides a welding structure and welding method for the oil filling hole of a pressure sensor, solving the problem of poor welding sealing at the oil filling hole of existing pressure sensors.

[0005] A welded structure for an oil filling hole of a pressure sensor includes: a housing and a pin, wherein an oil filling hole is provided inside the housing, the two ends of the oil filling hole are respectively connected to an oil storage area and an inner cavity, and a boss is provided between the oil storage area and the oil filling hole.

[0006] The pin is inserted into the oil filling hole and is in contact with the hole wall surface. The pin head is in contact with the boss. The pin is electrically connected to the upper electrode, and the outer shell is electrically connected to the lower electrode.

[0007] Furthermore, the head end of the aforementioned pin is configured as a guide head, which is tapered with a taper range of 1:20 to 1:10.

[0008] Furthermore, the length of the guide head is 1.0 to 1.5 times the diameter of the oil filling hole, the middle section length of the pin is 0.5 to 1.0 times the diameter of the oil filling hole, and the diameter of the pin head is the same as the diameter of the boss.

[0009] Furthermore, the diameter of the aforementioned boss is 1.4 to 1.6 times the diameter of the oil filling hole, and the height of the top surface of the boss is higher than the bottom surface of the oil storage area, with the height exceeding the bottom surface by 0.3 to 0.5 times the diameter of the oil filling hole.

[0010] Furthermore, the space containing the aforementioned oil storage area is cylindrical in shape, with a height twice the diameter of the filling hole.

[0011] Furthermore, a welding ring groove is provided near the boss in the oil storage area. The welding ring groove surrounds the boss and the bottom of the welding ring groove is lower than the bottom surface of the oil storage area.

[0012] Furthermore, the width of the welded ring groove is 0.4 to 0.6 times the diameter of the oil filling hole, the bottom of the welded ring groove is lower than the bottom surface of the oil storage area, and the height difference is 0.7 to 1.0 times the diameter of the oil filling hole.

[0013] Furthermore, both the aforementioned pins and the outer casing are made of stainless steel.

[0014] A welding method for the oil filling hole of a pressure sensor, based on the above-mentioned welding structure, includes the following steps:

[0015] S1: Insert the pin into the oil filling hole and ensure that the outer wall of the pin is flush with the outer wall of the boss.

[0016] S2: Move the assembled shell to the platform of the lower electrode and press the upper electrode vertically onto the pin head;

[0017] S3: The upper electrode is started and energized with a current of I1, maintaining preheating for a duration of t1.

[0018] S4: Increase the current to I2 based on the preheating current before welding, carry out the welding process, and maintain it for t2 time;

[0019] S5: After welding, reduce the current I2 to I3 and maintain post-weld annealing for t3 time, where the current value I3 is greater than I1.

[0020] S6: Clean the entire exterior of the pressure sensor filled with oil to remove any residual oil from the surface;

[0021] In the three stages of preheating, welding, and post-weld annealing, an electrode force of magnitude F is applied to the pin through the upper electrode.

[0022] The present invention has the following beneficial effects:

[0023] (1) The pressure sensor of the present invention improves the previous steel ball sealing method by adopting pin sealing, which not only makes assembly more convenient, but also changes the welding contact part from point-to-surface contact to surface-to-surface contact, thereby improving the fault tolerance rate in the sealing welding process.

[0024] (2) The pressure sensor of the present invention has an oil storage area outside the oil filling hole. The oil storage area is filled with oil. Before and after welding, the entire welding part is always immersed in oil, which avoids the loss of oil in the inner cavity during the welding process and ensures that the oil in the inner cavity is sufficient.

[0025] (3) The pressure sensor of the present invention has a boss and a welding ring groove in the oil storage area, which can quickly accumulate welding heat during welding, promote the boss to reach the melting state quickly, and improve the welding quality.

[0026] (4) The pressure sensor of the present invention completes the welding in three stages: preheating before welding, welding and post-weld annealing. The welding effect is good and the sealing reliability is high. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall welding structure of the oil filling hole of the pressure sensor of the present invention;

[0028] Figure 2 This is a schematic diagram of the pressure sensor of the present invention after it has been filled with oil.

[0029] Figure 3 This is a waveform diagram showing the magnitude of electrode force / current and its variation with time during the welding process in this invention.

[0030] In the diagram: 1-outer shell; 2-pin; 3-upper electrode; 4-lower electrode; 5-oil filling hole; 6-guide head; 7-bore; 8-welding annular groove; 9-oil storage area; 10-inner chamber. Detailed Implementation

[0031] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0032] Example 1

[0033] refer to Figure 1 and Figure 2 The present invention provides a welding structure for the oil filling hole of a pressure sensor, comprising: a housing 1 and a pin 2, wherein the pin 2 and the housing 1 are both made of stainless steel, which facilitates the transfer and accumulation of heat during the welding process.

[0034] The outer casing 1 has a vertically oriented oil filling hole 5 inside. The outer end of the oil filling hole 5 (i.e., the upper side of the outer casing 1) communicates with the oil storage area 9, and the inner end of the oil filling hole 5 communicates with the inner chamber 10. The inner chamber 10 needs to be filled with oil to achieve the purpose of manufacturing a high-quality pressure sensor. When filling the inner chamber 10 with oil, the oil must pass through the oil storage area 9. The oil storage area 9 provides a large space to improve filling efficiency, and also stores the oil while filling the inner chamber 10, keeping the liquid level higher than the welding area to prevent oil loss in the inner chamber 10 during the welding operation.

[0035] A ring-shaped boss 7 is provided between the oil storage area 9 and the oil filling hole 5. The pin 2 is inserted into the oil filling hole 5 and is in contact with the hole wall surface of the oil filling hole 5. The pin head of the pin 2 is in contact with the boss 7. At the same time, the pin 2 is electrically connected to the upper electrode 3, and the outer shell 1 is electrically connected to the lower electrode 4. The upper electrode 3 and the lower electrode 4 are connected to the power supply to provide energy for the pin 2 to be sealed and welded to the oil filling hole 5.

[0036] The head end of the pin 2 is set as a guide head 6. The guide head 6 is tapered, which serves to guide the assembly and prevent the assembly from being skewed. The appropriate range of the taper is 1:20 to 1:10.

[0037] Preferably, the length of the guide head 6 is 1.0 to 1.5 times the diameter of the oil filling hole 5, the middle section length of the pin 2 is 0.5 to 1.0 times the diameter of the oil filling hole 5, and the diameter of the pin head 2 is the same as the diameter of the boss 7.

[0038] Preferably, the diameter of the boss 7 is 1.4 to 1.6 times the diameter of the oil filling hole 5, and the height of the top surface of the boss 7 is higher than the bottom surface of the oil storage area 9, and its height is 0.3 to 0.5 times the diameter of the oil filling hole 5.

[0039] Preferably, the space containing the oil storage area 9 is cylindrical, and its height is twice the diameter of the oil filling hole 5.

[0040] A welding annular groove 8 is provided near the boss 7 within the oil storage area 9. The welding annular groove 8 is circular and surrounds the boss 7. The bottom of the welding annular groove 8 is lower than the bottom surface of the oil storage area 9. The welding annular groove 8 makes the boss 7 more prominent, which is conducive to the accumulation of welding heat during the welding process, improves the heat value of the welding part between the outer shell 1 and the pin 2, promotes the boss 7 to reach the melting state quickly, and improves the welding quality.

[0041] Preferably, the width of the welding ring groove 8 is 0.4 to 0.6 times the diameter of the oil filling hole 5, the bottom of the welding ring groove 8 is lower than the bottom surface of the oil storage area 9, and the height difference is 0.7 to 1.0 times the diameter of the oil filling hole 5.

[0042] The pressure sensor of the present invention improves upon the previous steel ball sealing method by using a pin 2 seal, which not only makes assembly more convenient but also improves the fault tolerance rate in the sealing welding process.

[0043] Example 2

[0044] A welding method for the oil filling hole of a pressure sensor, based on the above-mentioned welding structure, includes the following steps:

[0045] S1: Insert the pin 2 into the oil filling hole 5 and ensure that the outer wall of the pin 2 is flush with the outer wall of the boss 7.

[0046] S2: Move the assembled outer shell 1 to the platform of the lower electrode 4, and press the upper electrode 3 vertically onto the nail head of the pin 2;

[0047] S3: The upper electrode 3 is started and energized with a current of I1, maintaining preheating for a duration of t1.

[0048] S4: Increase the current to I2 based on the preheating current before welding, carry out the welding process, and maintain it for t2 time;

[0049] S5: After welding, reduce the current I2 to I3 and maintain post-weld annealing for t3 time, where the current value I3 is greater than I1.

[0050] S6: Clean the entire exterior of the pressure sensor filled with oil, remove any residual oil from the surface, and obtain a pressure sensor filled with oil and with the oil filling hole 5 sealed.

[0051] In the three stages of preheating, welding, and post-weld annealing, an electrode force of magnitude F is applied to the pin 2 by the upper electrode 3. The changes in the current during preheating, welding, and post-weld annealing are referenced. Figure 3 .

[0052] The pressure sensor of the present invention completes the welding process in three stages: preheating before welding, welding, and post-weld annealing. The welding effect is good and the sealing reliability is high.

[0053] Example 3

[0054] This embodiment is based on Embodiment 2. Taking the diameter of the oil filling hole 5 as 1mm as an example, the welding current I2 is 2kA to 3kA, and the energizing duration t2 is 20ms to 30ms; the preheating current I1 before welding is 50% to 80% of the welding current I2, and the energizing duration t1 is 10ms to 20ms; the annealing current I3 after welding is 40% to 60% of the welding current I2, and the energizing duration t3 is 30ms to 40ms.

[0055] The electrode force F is 1000N~1500N, and is continuously and stably applied from the preheating and energizing before welding to 200ms~400ms after welding annealing.

[0056] The above description is merely a preferred embodiment of the present invention, and does not represent all possible forms of the present invention. The scope of protection of the present invention is not limited to such specific statements and embodiments. Various other modifications and improvements can be made based on the technical teachings disclosed in the present invention without departing from the essence of the present invention, and these modifications and improvements are still within the scope of protection of the present invention.

Claims

1. A welded structure for an oil filling hole in a pressure sensor, characterized in that, include: The outer shell (1) and the pin (2) are provided. The inner part of the outer shell (1) is provided with an oil filling hole (5). The two ends of the oil filling hole (5) are respectively connected to the oil storage area (9) and the inner cavity (10). A boss (7) is provided between the oil storage area (9) and the oil filling hole (5). The pin (2) is inserted into the oil filling hole (5) and is in contact with the hole wall surface of the oil filling hole (5). The pin head (2) is in contact with the boss (7). The pin (2) is electrically connected to the upper electrode (3), and the outer shell (1) is electrically connected to the lower electrode (4).

2. The welded structure of a pressure sensor oil-filling hole according to claim 1, wherein The head end of the pin (2) is configured as a guide head (6), which is tapered with a taper range of 1:20 to 1:

10.

3. The welded structure of the oil-filling hole of the pressure sensor according to claim 2, characterized by, The length of the guide head (6) is 1.0 to 1.5 times the diameter of the oil filling hole (5), the middle section length of the pin (2) is 0.5 to 1.0 times the diameter of the oil filling hole (5), and the diameter of the pin head (2) is the same as the diameter of the boss (7).

4. The welded structure of the oil-filling hole of the pressure sensor according to claim 3, characterized by, The diameter of the boss (7) is 1.4 to 1.6 times the diameter of the oil filling hole (5), and the height of the top surface of the boss (7) is higher than the bottom surface of the oil storage area (9), and its height is 0.3 to 0.5 times the diameter of the oil filling hole (5).

5. The welded structure of a pressure sensor oil-filling hole according to claim 4, wherein The space containing the oil storage area (9) is cylindrical in shape, and its height is twice the diameter of the oil filling hole (5).

6. The welded structure of a pressure sensor oil-filling hole according to any one of claims 1 to 5, characterized in that, The oil storage area (9) is provided with a welding ring groove (8) near the boss (7). The welding ring groove (8) is arranged around the boss (7) in a circle, and the bottom of the welding ring groove (8) is lower than the bottom surface of the oil storage area (9).

7. The welded structure of a pressure sensor oil-filling hole according to claim 6, wherein The width of the welding ring groove (8) is 0.4 to 0.6 times the diameter of the oil filling hole (5). The bottom of the welding ring groove (8) is lower than the bottom surface of the oil storage area (9), and the height difference is 0.7 to 1.0 times the diameter of the oil filling hole (5).

8. The welded structure of a pressure sensor oil-filling hole according to claim 1, wherein Both the pin (2) and the outer shell (1) are made of stainless steel.

9. A welding method for an oil filling hole of a pressure sensor, based on the welding structure described in claim 6, comprising the following steps: S1: Insert the pin (2) into the oil filling hole (5) and ensure that the outer wall of the pin (2) is flush with the outer wall of the boss (7); S2: Move the assembled outer shell (1) as a whole to the platform of the lower electrode (4), and press the upper electrode (3) vertically onto the nail head of the pin (2); S3: The upper electrode (3) is started and energized with a current of I1, maintaining a preheating time of t1 before welding; S4: Increase the current to I2 based on the preheating current before welding, carry out the welding process, and maintain it for t2 time; S5: After welding, reduce the current I2 to I3 and maintain post-weld annealing for t3 time, where the current value I3 is greater than I1. S6: Clean the entire exterior of the pressure sensor filled with oil to remove any residual oil from the surface.

10. The method of claim 9, wherein the welding is performed by a laser beam. In the three stages of preheating, welding and post-weld annealing, an electrode force of magnitude F is applied to the pin (2) through the upper electrode (3).

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