Pin seal structure for temperature sensor

Abstract

A PIN sealing structure for a temperature sensor includes a back seat and a plastic shell. The upper end of the back seat is connected to the lower end of the plastic shell. A temperature sensing chip is disposed inside the back seat, and the upper end of the temperature sensing chip is connected to the lower ends of two PIN pins. The key feature is that the middle portion of the middle section of each PIN pin is encased in a heat-shrink tubing, and both the heat-shrink tubing and the middle section of the PIN pin are encased in the plastic shell, with the upper end of the PIN pin exposed outside the plastic shell. This invention adds heat-shrink tubing to the outside of the PIN pin, enabling the heat-shrink tubing to adhere tightly to the PIN pin surface under injection molding pressure, improving the airtightness of the PIN pin, increasing the airtightness of the sensor under extreme conditions, and preventing the sensor from malfunctioning due to moisture absorption under negative pressure.

Description

Technical Field

[0001] This utility model relates to the field of physics, and more particularly to temperature sensors, especially a PIN pin sealing structure for a temperature sensor. Background Technology

[0002] In the prior art, temperature sensors generally adopt an integral injection molding structure. For example, the exhaust gas temperature sensor disclosed in Chinese utility model patent with publication number CN215004020U discloses that the lower end of the PIN pin is connected to the temperature measuring chip, and the outer side of the connection between the PIN pin and the temperature measuring chip is injection molded to form a plastic kit. The PIN pin is the electrode that connects the temperature measuring element.

[0003] However, due to the difference in thermal expansion coefficients between the injection molding material and the metal pins, the product is prone to drawing moisture into the temperature sensor under harsh low-temperature, water-related, and high-temperature and high-humidity environments, creating a negative pressure condition inside the sensor. The directly injection-molded temperature sensing chip will be damaged by ion migration after absorbing moisture, leading to sensor failure. Furthermore, since moisture can reach a dew point under certain conditions, it directly affects the insulation of the sensor pins relative to the sensor's metal housing, causing signal point deviation and failure during operational use. Summary of the Invention

[0004] The purpose of this invention is to provide a PIN sealing structure for a temperature sensor, which solves the technical problem in the prior art where the PIN of a temperature sensor is directly plastic-sealed, making it prone to moisture absorption and failure.

[0005] The PIN sealing structure of this temperature sensor includes a back seat and a plastic shell. The upper end of the back seat is connected to the lower end of the plastic shell. A temperature sensing chip is disposed inside the back seat. The upper end of the temperature sensing chip is connected to the lower ends of two PIN pins. The key feature is that the middle part of the middle section of each PIN pin is covered by a heat shrink tubing. Both the heat shrink tubing and the middle section of the PIN pin are covered by the plastic shell, and the upper end of the PIN pin is exposed outside the plastic shell.

[0006] Furthermore, the heat shrink tubing is a double-walled heat shrink tubing, which includes an outer layer and an inner layer. The outer layer is a cross-linked polyolefin layer, and the inner layer is a hot melt adhesive layer. The outer surface of the cross-linked polyolefin layer is fused and fixed to the plastic shell, and the hot melt adhesive layer is bonded to the surface of the PIN pin.

[0007] Furthermore, the PIN pin has multiple circumferential protrusions at the coverage area of ​​the heat shrink tubing.

[0008] Furthermore, the PIN pin has grooves on the upper and lower sides of the heat shrink tubing covering area, and the plastic shell is embedded in the grooves.

[0009] Compared with existing technologies, the advantages of this invention are positive and significant. This invention adds heat-shrink tubing to the outside of the PIN pin, allowing the tubing to adhere tightly to the PIN pin surface under injection pressure, improving the airtightness between the PIN pin and the plastic housing, and preventing the sensor from malfunctioning due to moisture absorption under negative pressure conditions. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the structure of this utility model.

[0011] Figure 2 This is a cross-sectional view of the present invention.

[0012] Figure 3 This is a schematic diagram of the PIN pin and heat shrink tubing of this utility model.

[0013] Figure 4 This is a schematic diagram of the PIN pin of this utility model.

[0014] The markings in the diagram are: 1. Back seat; 2. Plastic shell; 3. PIN pin; 301. Groove; 302. Protrusion; 4. Temperature sensing chip; 5. Heat shrink tubing; 501. Cross-linked polyolefin layer; 502. Hot melt adhesive layer. Detailed Implementation

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this does not limit the present invention.

[0016] like Figures 1-4 As shown, the present invention discloses a PIN pin sealing structure for a temperature sensor, comprising a back seat 1 and a plastic shell 2. The upper end of the back seat 1 is connected to the lower end of the plastic shell 2. A temperature sensing chip 4 is disposed inside the back seat 1, and the upper end of the temperature sensing chip 4 is connected to the lower ends of two PIN pins 3. The characteristic feature is that the middle part of the middle section of any one of the PIN pins 3 is each covered by a heat shrink tubing 5, and both the heat shrink tubing 5 and the middle section of the PIN pin 3 are covered by the plastic shell 2, with the upper end of the PIN pin 3 exposed outside the plastic shell 2.

[0017] Specifically, the upper end of the back seat 1 is sealed to the plastic shell 2. The temperature measuring chip 4 is used to measure the temperature. The upper end of the PIN pin 3 is exposed outside the plastic shell 2 to connect the signal of the temperature measuring chip 4 to the outside. The middle part of the middle section of the PIN pin 3 is covered inside the heat shrink tubing 5, which enables the heat shrink tubing 5 to adhere tightly to the surface of the PIN pin 3 under injection pressure, thereby improving the airtightness between the PIN pin 3 and the plastic shell 2. The heat shrink tubing 5 and the middle section of the PIN pin 3 are covered inside the plastic shell 2 to fix the PIN pin 3.

[0018] Furthermore, the heat shrink tubing 5 is a double-walled heat shrink tubing, comprising an outer layer and an inner layer. The outer layer is a cross-linked polyolefin layer 501, and the inner layer is a hot melt adhesive layer 502. The outer surface of the cross-linked polyolefin layer 501 is fused and fixed to the plastic shell 2, and the hot melt adhesive layer 502 is bonded to the surface of the PIN pin 3. Specifically, the outer surface of the cross-linked polyolefin layer 501 fuses with the resin at high temperature during the molding process of the plastic shell 2, and the hot melt adhesive layer 502 adheres tightly to the surface of the PIN pin 3 under injection pressure, increasing the adhesion and airtightness of the heat shrink tubing 5.

[0019] Furthermore, the PIN pin 3 has multiple circumferential protrusions 302 on the surface of the area covered by the heat shrink tubing 5.

[0020] Specifically, the protrusion 302 is set on the outer peripheral surface of the middle of the PIN pin 3, giving the middle of the PIN pin 3 a rough surface. When the heat shrink tubing 5 shrinks, under the pressure of injection molding, the hot melt adhesive layer 502 covers the outside of the protrusion 302 of the PIN pin 3, increasing the penetration path of moisture, making it more difficult for moisture to penetrate, and increasing the damping between the heat shrink tubing 5 and the PIN pin 3, thereby improving the airtightness of the PIN pin 3 under extreme conditions.

[0021] Furthermore, the PIN pin 3 has grooves 301 on the upper and lower sides of the heat shrink tubing 5 covering area, and the plastic shell 2 is embedded in the grooves 301.

[0022] Specifically, the grooves 301 on the upper and lower sides of the heat shrink tubing 5 covering the PIN pin 3 can increase the damping between the PIN pin 3 and the plastic shell 2, preventing relative movement between the PIN pin 3 and the plastic shell 2, which would affect the insertion and sealing effect.

[0023] In use, a heat shrink tubing 5 is added in the middle of the PIN pin 3. The cross-linked polyolefin layer 501 on the outer layer of the heat shrink tubing 5 fuses with the resin at high temperature during the injection molding of the plastic shell 2. The hot melt adhesive layer 502 on the inner layer adheres tightly to the surface of the PIN pin 3 under injection pressure and flows into the protrusion 302 on the outer side of the PIN pin 3, increasing the adhesion and airtightness of the heat shrink tubing 5. The groove 301 of the PIN pin 3 is embedded in the plastic shell 2, which increases the damping between the PIN pin 3 and the plastic shell 2, preventing relative movement between the PIN pin 3 and the plastic shell 2 from affecting the insertion and sealing effect. This can effectively improve the airtightness of the temperature sensor under extreme conditions and prevent the temperature sensor from absorbing moisture and failing under negative pressure conditions.

Claims

1. A PIN sealing structure for a temperature sensor, comprising a back seat (1) and a plastic shell (2), wherein the upper end of the back seat (1) is connected to the lower end of the plastic shell (2), and a temperature sensing chip (4) is disposed inside the back seat (1), the upper end of the temperature sensing chip (4) being connected to the lower ends of two PIN pins (3), characterized in that: The middle section of any one of the PIN pins (3) is covered by a heat shrink tube (5), and the middle section of any one of the heat shrink tubes (5) and the PIN pin (3) is covered by the plastic shell (2), with the upper end of the PIN pin (3) exposed outside the plastic shell (2).

2. The PIN sealing structure of the temperature sensor as described in claim 1, characterized in that: The heat shrink tubing (5) is a double-walled heat shrink tubing, which includes an outer layer and an inner layer. The outer layer is a cross-linked polyolefin layer (501), and the inner layer is a hot melt adhesive layer (502). The outer surface of the cross-linked polyolefin layer (501) is fused and fixed with the plastic shell (2), and the hot melt adhesive layer (502) is bonded to the surface of the PIN pin (3).

3. The PIN sealing structure of the temperature sensor as described in claim 2, characterized in that: The PIN pin (3) has multiple circumferential protrusions (302) on the surface of the heat shrink tubing (5) covering area.

4. The PIN sealing structure of the temperature sensor as described in claim 1, characterized in that: The PIN pin (3) has grooves (301) on the upper and lower sides of the heat shrink tubing (5) covering area, and the plastic shell (2) is embedded in the grooves (301).

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