Sensor for measuring pressure and temperature of natural gas

Abstract

The utility model relates to a sensor for measuring pressure and temperature of natural gas. The sensor comprises a connector and a lower shell, the lower shell sequentially comprises an integrally-formed hexagonal base, a threaded part and a thin-wall protection tube from top to bottom. A supporting seat is arranged in the hexagonal base; an absolute pressure ceramic pressure sensor is mounted on the supporting seat; an FPC (Flexible Printed Circuit) is arranged between the absolute pressure ceramic pressure sensor and the connector pin; an air inlet channel is formed in the lower part of the supporting seat; and an NTC thermistor is welded on a bonding pad on the bottom surface of the supporting seat, the other end of the NTC thermistor extends into the thin-wall protection tube, and the length of the NTC thermistor exceeds that of the thread part. The NTC thermistor is arranged in the thin-wall protection tube, so that the internal NTC thermistor can be protected from being directly impacted by external humidity and pressure, interference of external environmental factors on the temperature sensor is avoided, and the protection performance is good. And meanwhile, the integrated absolute pressure ceramic pressure sensor is adopted, so that the cost of the pressure sensor is effectively reduced, and the anti-interference performance and the long-term stability are relatively good.

Description

Technical Field

[0001] This utility model relates to the field of gas rail control for natural gas fuel vehicles, and in particular to a sensor for measuring the pressure and temperature of natural gas. Background Technology

[0002] Natural gas heavy-duty trucks refer to heavy-duty vehicles that use natural gas as fuel. Compared to traditional vehicles, the traditional engine is replaced with a natural gas engine with a gas rail assembly that uses a mixer. The gas rail includes an upper rail, a lower rail, and natural gas injectors arranged in a ring between the upper and lower rails. The pressure and temperature of the natural gas injected into the gas rail are monitored and controlled by sensors.

[0003] Currently, China relies heavily on imports for integrated sensors used in monitoring natural gas pressure and temperature. While imported natural gas pressure and temperature sensors employ MEMS eutectic technology (back pressure) for their pressure sensors, offering good protection, they suffer from low batch production efficiency and high manufacturing costs. Chinese patents CN206161224U and CN206019866U both disclose a gas pressure and temperature sensor, but the exposed portions of the NCT sensors in these patents lack adequate protection. Furthermore, the temperature and pressure measurement inlet channels are the same, making them susceptible to interference from external impurities such as water vapor and metal particles, which can affect measurement accuracy. Additionally, using pressure chips as pressure sensors results in fragile structures, susceptibility to external impacts, limited application environments, and higher costs compared to other pressure sensors. Utility Model Content

[0004] To address the issues of insufficient protection for the exposed NTC portion, poor stability of the pressure chip, and high cost in existing natural gas pressure and temperature sensors, this invention provides a natural gas pressure and temperature sensor, comprising: a connector and a lower housing.

[0005] The connector has a vertically arranged connector pin.

[0006] The lower outer shell comprises, from top to bottom, an integrally formed hexagonal base, a threaded portion, and a thin-walled protective tube; one end of the thin-walled protective tube extends into the threaded portion, and the other end protrudes to the outside.

[0007] A support base is provided inside the hexagonal base; a first groove is provided on the upper surface of the support base, and a first O-ring and an absolute pressure ceramic pressure sensor are sequentially installed on the first groove; an FPC flexible circuit board is provided between the absolute pressure ceramic pressure sensor and the connector pin, one end of the FPC flexible circuit board is soldered to the absolute pressure ceramic pressure sensor, the other end is soldered to the lower part of the connector pin, and the middle is soldered to the support base pin; an SMT surface mount circuit and a conditioning chip are provided at the solder joint between the FPC flexible circuit board and the absolute pressure ceramic pressure sensor;

[0008] The lower surface of the support base is provided with a second groove, and a second O-ring is provided in the second groove; a through hole is provided between the second groove and the first groove, penetrating the support base;

[0009] The lower part of the support base is provided with an air intake channel, and the lower part of the threaded part is provided with an air inlet. The air intake channel is connected to the through hole.

[0010] An NTC thermistor is soldered onto the bottom pad of the support base. The other end of the NTC thermistor extends into the thin-walled protective tube, and its length exceeds the threaded portion.

[0011] Furthermore, thermally conductive adhesive is provided in the lower part of the thin-walled protective tube.

[0012] Furthermore, the thin-walled protective tube is inclined, with its lower end located on the central axis of the lower outer shell.

[0013] Furthermore, the connector and the lower housing are joined by press riveting, and the connector is provided with sealant at the riveting point.

[0014] Furthermore, the first O-ring and the second O-ring are media sealing rings, and the material is FKM fluororubber.

[0015] Compared with the prior art, this utility model has the following beneficial effects:

[0016] By placing the NTC thermistor inside a thin-walled protective tube, the internal NTC thermistor is protected from direct impacts by external humidity and pressure, avoiding interference from external environmental factors on the temperature sensor, thus providing good protection. Simultaneously, the use of an integrated absolute pressure ceramic pressure sensor not only effectively reduces the cost of the pressure sensor but also allows it to operate normally in high-temperature environments. Furthermore, the inherent chemical stability of ceramics gives it excellent corrosion resistance, good anti-interference performance, and long-term stability. Attached Figure Description

[0017] Figure 1 This is a structural diagram of a natural gas pressure and temperature sensor according to the present invention.

[0018] Figure 2 for Figure 1 Sectional view along direction AA;

[0019] In the diagram: 1. Connector; 2. Hexagonal base; 3. Threaded part; 4. Thin-walled protective tube; 5. Support base; 6. NTC thermistor; 7. Air intake channel; 8. Air inlet; 9. First O-ring; 10. Absolute pressure ceramic pressure sensor; 11. Second O-ring; 12. FPC flexible circuit board; 13. Connector pin; 14. Thermally conductive adhesive; 15. Sealant; 16. Through hole; 17. Support base pin. Detailed Implementation

[0020] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0021] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. The terms "upper," "lower," "front," "rear," "top," "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or part referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. It should be understood that such data can be interchanged where appropriate for the embodiments of this utility model described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0022] like Figure 1 and Figure 2 As shown, a natural gas pressure and temperature sensor includes: a connector 1 and a lower housing; a connector pin 13 is vertically disposed inside the connector 1.

[0023] The lower outer casing, from top to bottom, comprises an integrally molded hexagonal base 2, a threaded portion 3, and a thin-walled protective tube 4; one end of the thin-walled protective tube 4 extends into the threaded portion 3, while the other end protrudes externally. The hexagonal base 2 and the threaded portion 3 connect external pressure and seal internal pressure, simultaneously protecting the internal electronic components from external environmental interference. The thin-walled protective tube 4 is brazed to the threaded portion.

[0024] A support base 5 is provided inside the hexagonal base 2. A first groove is provided on the upper surface of the support base 5, and a first O-ring 9 and an absolute pressure ceramic sensor 10 are sequentially installed in the first groove. An FPC flexible circuit board 12 is provided between the absolute pressure ceramic sensor 10 and the connector pin 13. One end of the FPC flexible circuit board 12 is soldered to the absolute pressure ceramic sensor 10, the other end is soldered to the lower part of the connector pin 13, and the middle is soldered to the support base pin 17. An SMT surface mount circuit and a conditioning chip are provided at the solder joint between the FPC flexible circuit board 12 and the absolute pressure ceramic sensor 10.

[0025] The lower surface of the support base 5 is provided with a second groove, and a second O-ring 11 is provided in the second groove; a through hole 16 is provided between the second groove and the first groove, penetrating the support base 5.

[0026] The support base 5 has an air intake channel 7 at its lower part and an air inlet 8 at the lower part of the threaded part 3. The air intake channel 7 is connected to the through hole 16.

[0027] An NTC thermistor 6 is soldered onto the bottom pad of the support base 5. The other end of the NTC thermistor 6 extends into the thin-walled protective tube 4, and its length exceeds the threaded part 3.

[0028] The working principle of a natural gas pressure and temperature sensor disclosed in this application is as follows:

[0029] The pressure and temperature of natural gas are measured independently via two separate paths.

[0030] Temperature measurement path: The NTC thermistor 6 converts external temperature changes into resistance changes, thus measuring the temperature of the natural gas. By placing the NTC thermistor 6 inside the thin-walled protective tube 4, it is protected from direct impacts by external humidity and pressure, avoiding interference from external environmental factors on the temperature sensor, thus providing good protection.

[0031] Pressure measurement path: Natural gas enters the space to be measured through the inlet 8 and inlet channel 7 and through the through hole 16. The absolute pressure ceramic pressure sensor 10 measures the external natural gas pressure and provides power protection and output filtering.

[0032] The support base 5 bears the internal pressure of the seal. In order to ensure the sealing of the connector 1, O-rings are provided on both the upper and lower surfaces of the support base 5 to prevent external moisture, electronic particles, etc. from entering the upper space inside the connector 1.

[0033] The NTC thermistor 6 is soldered to the support base 5, which has a support base pin 17 embedded inside to connect to the solder pad. The temperature signal is transmitted to the FPC flexible circuit board 12 through the support base pin 17.

[0034] Because the FPC flexible circuit board 12 is thin, flexible, and easy to bend, it effectively utilizes the internal space. By bending, the FPC flexible circuit board 12 is soldered to the absolute pressure ceramic pressure sensor 10, the support base pin 17, and the connector pin 13 respectively. The pressure signal measured by the absolute pressure ceramic pressure sensor 10 and the temperature signal measured by the NTC thermistor 6 are transmitted to the connector pin 13, and then the pressure and temperature signals are transmitted to the external wiring harness through the connector 1.

[0035] In order to better conduct external heat to the NTC, thermally conductive adhesive 14 is provided in the lower part of the thin-walled protective tube 4 to increase the thermal conductivity.

[0036] The thin-walled protective tube 4 is installed at an angle, with its lower end located on the central axis of the lower outer casing. The thin-walled protective tube 4 is brazed at an angle, which ensures the measured temperature without affecting the limitation of the radial direction of installation.

[0037] Connector 1 and the lower housing are joined by press riveting. To ensure the sealing of connector 1 and the lower housing after assembly, sealant 15 is provided at the riveting point of connector 1 to ensure that the internal sensor and circuit are not affected by external humidity and moisture.

[0038] The first O-ring 9 and the second O-ring 11 are medium-resistant sealing rings for natural gas, and the material is FKM fluororubber.

[0039] The above description is merely a preferred embodiment of this utility model and is not intended to limit the scope of implementation of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this utility model, and all such improvements and modifications should be covered within the protection scope of this utility model.

Claims

1. A natural gas pressure temperature sensor comprising: The utility model relates to a connector (1) and lower shell. The connector (1) is vertically arranged with connector pins (13) inside; The lower shell comprises a hexagonal base (2), a threaded part (3) and a thin-walled protective tube (4) from top to bottom; the thin-walled protective tube (4) extends into the threaded part (3) at one end and is exposed outside at the other end; The hexagonal base (2) is internally provided with a support seat (5); the upper surface of the support seat (5) is provided with a first groove, and the first groove is sequentially provided with a first O-ring (9) and an absolute pressure ceramic pressure sensor (10); an FPC flexible circuit board (12) is arranged between the absolute pressure ceramic pressure sensor (10) and the connector pins (13), one end of the FPC flexible circuit board (12) is welded to the absolute pressure ceramic pressure sensor (10), the other end is welded to the lower part of the connector pins (13), and the middle part is welded to a support seat pin (17); an SMT patch circuit and a conditioning chip are arranged at the welding position of the FPC flexible circuit board (12) and the absolute pressure ceramic pressure sensor (10); The lower surface of the support seat (5) is provided with a second groove, and the second groove is provided with a second O-ring (11); a through hole (16) penetrating through the support seat (5) is arranged between the first groove and the second groove; The lower part of the support seat (5) is provided with an air inlet channel (7), and the lower part of the threaded part (3) is provided with an air inlet (8); the air inlet channel (7) is in communication with the through hole (16); An NTC thermistor (6) is welded on the bottom pad of the support seat (5), the other end of the NTC thermistor (6) extends into the thin-walled protective tube (4), and the length exceeds the threaded part (3). The thin-walled protective tube (4) is internally provided with a heat-conducting adhesive (14) at the lower part.

2. The pressure-temperature sensor for measuring natural gas according to claim 1, wherein The thin-walled protective tube (4) is obliquely arranged, and the lower end is located on the central axis of the lower shell.

3. The pressure-temperature sensor for measuring natural gas according to claim 1, wherein The connector (1) and the lower shell are connected by pressure riveting, and the connector (1) is provided with sealing glue (15) at the riveting position.

4. The pressure-temperature sensor for measuring natural gas according to claim 1, wherein The first O-ring (9) and the second O-ring (11) are medium sealing rings, and the material is FKM fluororubber.

5. The pressure-temperature sensor for measuring natural gas according to claim 1, wherein ​

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