Double-chip oil-filled differential pressure sensor

Abstract

The invention belongs to the technical field of sensors, and particularly discloses a double-chip oil-filled differential pressure sensor, which comprises a positive and negative symmetrical tube shell, a conductive pin, a glass insulator, chips, a gold wire, an isolation diaphragm, a compression ring, a lug welding structure and an oil filling hole. According to the invention, two chips with the same measuring range and the same batch are utilized, and the static pressure error influence is eliminated by designing differential circuit connection, so that the comprehensive precision of the sensor is optimized; in addition, a special lug structure is designed, welding with an external structure is achieved, and the air tightness and impact resistance of a product are effectively improved. The defects that an existing differential pressure sensor is large in static pressure error and low in comprehensive precision are overcome, and the problem that most differential pressure sensors do not have the welding and assembling capacity is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of sensors, and particularly relates to a double-chip oil-filled differential pressure sensor. Background Art

[0002] With the development of microelectromechanical system (MEMS) devices, silicon pressure sensors are increasingly widely used in industries such as aviation, aerospace, automotive, and petroleum. Among them, the silicon piezoresistive differential pressure sensor is a sensor used to measure the difference between two pressures, and is usually used to measure the pressure difference between the front and rear ends of a certain device or component. Differential pressure sensors are widely used in many high-precision measurement occasions such as micro-flow measurement, leak testing, environmental seal detection, gas flow measurement, and liquid level measurement.

[0003] Currently, most oil-filled differential pressure sensors use a single chip to collect pressure output, which has disadvantages such as poor positive and negative symmetry and inconsistent stress matching under static pressure, resulting in static pressure errors of the sensor and directly affecting the comprehensive accuracy of the sensor. Therefore, in order to solve the static pressure error of the differential pressure sensor and at the same time meet the working requirements in different test medium environments, a double-chip oil-filled differential pressure sensor is designed. Summary of the Invention

[0004] The purpose of the present invention is to solve the defects of large static pressure error and low comprehensive accuracy of existing differential pressure sensors, and the problem that most differential pressure sensors do not have welding and assembly capabilities, and a double-chip oil-filled differential pressure sensor is proposed.

[0005] The technical solution of the present invention is: a double-chip oil-filled differential pressure sensor, including a housing, and concave first and second sensing chambers are respectively arranged at the upper and lower ends of the housing; the first and second sensing chambers are both filled with a sensing oil; A first piezoresistive pressure sensor and a second piezoresistive pressure sensor are respectively arranged at the bottoms of the first and second sensing chambers; the first and second piezoresistive pressure sensors respectively output sensing signals through a first conductive pin and a second conductive pin; isolation diaphragms are arranged at the tops of the first and second sensing chambers, and the two isolation diaphragms are respectively connected to the housing through two pressure rings to seal the first and second sensing chambers; A first oil passage through-hole and a second oil passage through-hole are arranged inside the housing; one end of the first oil passage through-hole is connected to the first sensing chamber, and the other end is in contact with the bottom of the second piezoresistive pressure sensor; one end of the second oil passage through-hole is connected to the second sensing chamber, and the other end is in contact with the bottom of the first piezoresistive pressure sensor, so that the pressure in the first sensing chamber acts on the upper surface of the first piezoresistive pressure sensor and the lower surface of the second piezoresistive pressure sensor, and the pressure in the second sensing chamber acts on the lower surface of the first piezoresistive pressure sensor and the upper surface of the second piezoresistive pressure sensor, thereby forming a dual-chip oil-filled differential pressure sensing.

[0006] Preferably, both the first conductive pin and the second conductive pin are insulated from the housing through a cover glass insulator; the first conductive pin and the second conductive pin are respectively electrically connected to the first piezoresistive pressure sensor and the second piezoresistive pressure sensor through gold wire leads.

[0007] Preferably, the first piezoresistive pressure sensor and the second piezoresistive pressure sensor adopt SOI silicon piezoresistive gauge pressure chips with the same range.

[0008] Preferably, the outer surface of the housing is provided with a "lug" welding structure.

[0009] Preferably, the first piezoresistive pressure sensor and the second piezoresistive pressure sensor are respectively bonded and fixed to the bottoms of the first sensing chamber and the second sensing chamber through a high-temperature adhesive.

[0010] Preferably, a third oil passage through-hole and a fourth oil passage through-hole are further arranged inside the housing; one end of the third oil passage through-hole and one end of the fourth oil passage through-hole are both located on the outer surface of the housing and are respectively connected to the oil filling holes; the other end of the third oil passage through-hole and the other end of the fourth oil passage through-hole are respectively connected to the first sensing chamber and the second sensing chamber.

[0011] Preferably, an oil filling steel ball is arranged in the oil filling hole.

[0012] Preferably, the sensing oil is dimethyl silicone oil; the first oil passage through-hole and the second oil passage through-hole are arranged in parallel.

[0013] Preferably, both the housing and the pressure ring are made of stainless steel; the isolation diaphragm is an integrally formed stainless steel corrugated isolation diaphragm; the housing and the pressure ring are formed by laser welding.

[0014] Preferably, the housing, the first conductive pin, the second conductive pin and the glass insulator are integrally formed through a sintering and curing process.

[0015] 1. The present invention designs stress matching under static pressure by arranging chips of the same batch, same state, and same specification at both the positive and negative ends. Compared with a single chip, stress mismatch is caused by the asymmetry of the chip stacking structure and different materials, which affects the static pressure of the sensor. The present invention can effectively reduce the stress mismatch at both ends, effectively optimize the static pressure error, and improve the comprehensive accuracy of the sensor.

[0016] 2. The present invention proposes a special positive-negative symmetry structure design. By designing a shell structure and an oil passage structure that are symmetric in the positive and negative directions, and a completely symmetric chip layout, it ensures the symmetry of positive and negative pressures at both ends and effectively reduces the influence of static pressure error. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Shown is a schematic structural diagram of a dual-chip oil-filled differential pressure sensor.

[0018] Figure 2 Shown is a schematic structural diagram of the glass insulator of a dual-chip oil-filled differential pressure sensor.

[0019] Figure 3 Shown is a schematic diagram of the welding of the housing and the sensor of a dual-chip oil-filled differential pressure sensor.

[0020] Figure 4 Shown is a schematic diagram of the symmetric design of the differential oil circuit of a dual-chip.

[0021] Figure 5 Shown is a schematic diagram of the differential principle of a dual-chip.

[0022] Description of reference numerals: 1 - housing, 21 - first conductive pin, 22 - second conductive pin, 3 - glass insulator, 41 - first piezoresistive pressure sensor, 42 - second piezoresistive pressure sensor, 5 - gold wire, 6 - isolation diaphragm, 7 - compression ring, 81 - first oil passage through hole, 82 - second oil passage through hole, 83 - third oil passage through hole, 84 - fourth oil passage through hole, 9 - oil-filled steel ball, 10 - "lobe" welding structure, 11 - oil filling hole. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] Now, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood that the embodiments shown and described in the drawings are merely exemplary, intended to illustrate the principles and spirit of the present invention, and not to limit the scope of the present invention.

[0024] Example 1: As Figure 1 and Figure 2As shown in the figure, a double-chip oil-filled differential pressure sensor uses double chips of the same range and the same batch. By designing a differential circuit connection, the influence of static pressure error is eliminated, thereby optimizing the comprehensive accuracy of the sensor. In addition, a special "lug" structure is designed to realize welding with the external structure, effectively improving the airtightness and shock resistance of the product. The double-chip oil-filled differential pressure sensor includes: a housing 1, with concave first and second sensing chambers respectively arranged at the upper and lower ends of the housing 1; the first and second sensing chambers are both filled with a sensing oil; at the bottoms of the first and second sensing chambers, a first piezoresistive pressure sensor 41 and a second piezoresistive pressure sensor 42 are respectively arranged; the first piezoresistive pressure sensor 41 and the second piezoresistive pressure sensor 42 output sensing signals respectively through a first conductive pin 21 and a second conductive pin 22; at the tops of the first and second sensing chambers, isolation diaphragms 6 are both arranged, and the two isolation diaphragms 6 are respectively connected to the housing 1 through two pressure rings 7 to seal the first and second sensing chambers. In the housing 1, a first oil passage through hole 81 and a second oil passage through hole 82 are arranged; one end of the first oil passage through hole 81 is connected to the first sensing chamber, and the other end contacts the bottom of the second piezoresistive pressure sensor 42; one end of the second oil passage through hole 82 is connected to the second sensing chamber, and the other end contacts the bottom of the first piezoresistive pressure sensor 41, so that the pressure in the first sensing chamber acts on the upper surface of the first piezoresistive pressure sensor 41 and the lower surface of the second piezoresistive pressure sensor 42, and the pressure in the second sensing chamber acts on the lower surface of the first piezoresistive pressure sensor 41 and the upper surface of the second piezoresistive pressure sensor 42, thereby forming a double-chip oil-filled differential pressure sensing.

[0025] In this embodiment, both the first conductive pin 21 and the second conductive pin 22 are insulated from the housing 1 through a covering glass insulator 3; the first conductive pin 21 and the second conductive pin 22 are respectively electrically connected to the first piezoresistive pressure sensor 41 and the second piezoresistive pressure sensor 42 through gold wire leads 5.

[0026] In this embodiment, the first piezoresistive pressure sensor 41 and the second piezoresistive pressure sensor 42 adopt SOI silicon piezoresistive gauge pressure chips of the same range size. The first piezoresistive pressure sensor 41 and the second piezoresistive pressure sensor 42 are respectively bonded and fixed at the bottoms of the first and second sensing chambers through high-temperature adhesive.

[0027] In this embodiment, a "lug" welding structure 10 is arranged on the outer surface of the housing 1. As Figure 3As shown, when the dual-chip oil-filled differential pressure sensor needs to be welded to an external metal structure, the external metal structure is butt-assembled with the "lug" welding structure 10 to achieve the laser welding process, replacing the existing sensor adhesive process on the market, effectively improving the impact resistance and sealing performance.

[0028] In this embodiment, a third oil passage through hole 83 and a fourth oil passage through hole 84 are further provided inside the housing 1; one ends of the third oil passage through hole 83 and the fourth oil passage through hole 84 are both located on the outer surface of the housing 1 and are respectively connected to the oil filling holes 11; the other ends of the third oil passage through hole 83 and the fourth oil passage through hole 84 are respectively connected to the first sensing chamber and the second sensing chamber.

[0029] In this embodiment, an oil filling steel ball 9 is welded in the oil filling hole 11 by energy storage welding to completely seal the dimethyl silicone oil inside the cavity of the dual-chip oil-filled differential pressure sensor. When an external pressure acts on the surface of the isolation diaphragm 6, it is transmitted to the first piezoresistive pressure sensor 41 and the second piezoresistive pressure sensor 42 through the dimethyl silicone oil in each oil passage through hole.

[0030] In this embodiment, the sensing oil is dimethyl silicone oil; the first oil passage through hole 81 and the second oil passage through hole 82 are arranged in parallel.

[0031] In this embodiment, both the housing 1 and the pressure ring 7 are made of stainless steel; the isolation diaphragm 6 is an integrally formed stainless steel corrugated isolation diaphragm; the housing 1 and the pressure ring 7 are formed by laser welding, and it is better to use the same material for the housing 1, the isolation diaphragm 6 and the pressure ring 7 through laser welding.

[0032] In this embodiment, the housing 1, the first conductive pin 21, the second conductive pin 22 and the glass insulator 3 are integrally formed by the sintering and curing process.

[0033] The specific working principle and process of the present invention are as follows: Ideally, the zero point should remain unchanged when equal pressures are applied at both ends of the differential pressure sensor. In fact, due to the asymmetry of the chip surface layer structure and the stress mismatch on the surfaces of different materials, a static pressure error of the sensor is caused, directly affecting the comprehensive accuracy of the sensor.

[0034] Therefore, the present invention adopts a symmetrical design of the positive and negative structures of the sensor and a symmetrical design of the dual-chip differential oil circuits. As Figure 1 shown, the structures at both ends of the dual-chip oil-filled differential pressure sensor are designed to be processed symmetrically, reducing the zero-point deviation of the sensor caused by structural asymmetry and improving the comprehensive accuracy of the dual-chip oil-filled differential pressure sensor; as Figure 4As shown, a dual-chip differential oil circuit symmetric structure is designed. The pressure P1 is applied to the top of the pressure-sensitive diaphragm of the first piezoresistive pressure sensor 41 and the second piezoresistive pressure sensor 42, and at the same time acts on the bottom of the pressure-sensitive diaphragm of the second piezoresistive pressure sensor 42; the pressure P2 is applied to the top of the pressure-sensitive diaphragm of the second piezoresistive pressure sensor 42, and at the same time acts on the bottom of the pressure-sensitive diaphragm of the first piezoresistive pressure sensor 41. The symmetric oil circuit design at both ends ensures that the amount of dimethyl silicone oil is the same, and the influence of the gravity of the silicone oil on the zero output of the sensor under the action of gravity acceleration is reduced to the minimum; as Figure 5 As shown is the dual-chip differential principle, where represents the resistance of the piezoresistive pressure sensor, represents the change in the resistance of the piezoresistive pressure sensor, Vin+ and Vin- represent the voltages of the two input terminals, Vout+ and Vout- represent the positive and negative terminals of the differential output. The pressure P1 and the pressure P2 act on the first piezoresistive pressure sensor 41 and the second piezoresistive pressure sensor 42 respectively, and the output is the average of a front measurement and a back measurement, generating equal positive and negative pressure sensitivities, thereby eliminating the common-mode static pressure error.

[0035] Those of ordinary skill in the art will realize that the embodiments described herein are for helping the reader understand the principles of the present invention, and it should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those of ordinary skill in the art can make various other specific deformations and combinations that do not depart from the essence of the present invention according to these technical revelations disclosed by the present invention, and these deformations and combinations are still within the protection scope of the present invention.

Claims

1. A dual-chip oil-filled differential pressure sensor, characterized in that It includes a housing (1), with a concave first sensing chamber and a second sensing chamber respectively provided at the upper and lower ends of the housing (1); both the first sensing chamber and the second sensing chamber are filled with a sensing hydraulic fluid; At the bottoms of the first sensing chamber and the second sensing chamber, a first piezoresistive pressure sensor (41) and a second piezoresistive pressure sensor (42) are respectively provided; the first piezoresistive pressure sensor (41) and the second piezoresistive pressure sensor (42) output sensing signals respectively through a first conductive pin (21) and a second conductive pin (22); at the tops of the first sensing chamber and the second sensing chamber, isolation diaphragms (6) are both provided, and the two isolation diaphragms (6) are respectively connected to the housing (1) through two pressure rings (7) to realize the sealing of the first sensing chamber and the second sensing chamber; In the housing (1), a first oil passage through-hole (81) and a second oil passage through-hole (82) are provided; one end of the first oil passage through-hole (81) is connected to the first sensing chamber, and the other end contacts the bottom of the second piezoresistive pressure sensor (42); one end of the second oil passage through-hole (82) is connected to the second sensing chamber, and the other end contacts the bottom of the first piezoresistive pressure sensor (41), so that the pressure in the first sensing chamber acts on the upper surface of the first piezoresistive pressure sensor (41) and the lower surface of the second piezoresistive pressure sensor (42), and the pressure in the second sensing chamber acts on the lower surface of the first piezoresistive pressure sensor (41) and the upper surface of the second piezoresistive pressure sensor (42), thereby forming a dual-chip oil-filled differential pressure sensing.

2. The double-chip oil-filled differential pressure sensor according to claim 1, characterized in that, Both the first conductive pin (21) and the second conductive pin (22) are insulated from the housing (1) through a cover glass insulator (3); both the first conductive pin (21) and the second conductive pin (22) are electrically connected to the first piezoresistive pressure sensor (41) and the second piezoresistive pressure sensor (42) respectively through gold wire leads (5).

3. The double-chip oil-filled differential pressure sensor according to claim 1, characterized in that, The first piezoresistive pressure sensor (41) and the second piezoresistive pressure sensor (42) adopt SOI silicon piezoresistive gauge pressure chips with the same range size.

4. The double-chip oil-filled differential pressure sensor according to claim 1, characterized in that, On the outer surface of the housing (1), a "lug" welding structure (10) is provided.

5. The dual-chip oil-filled differential pressure sensor according to claim 1, wherein The first piezoresistive pressure sensor (41) and the second piezoresistive pressure sensor (42) are respectively bonded and fixed at the bottoms of the first sensing chamber and the second sensing chamber through a high-temperature adhesive.

6. The dual-chip oil-filled differential pressure sensor according to claim 1, wherein Inside the housing (1), a third oil passage through-hole (83) and a fourth oil passage through-hole (84) are also provided; one end of the third oil passage through-hole (83) and one end of the fourth oil passage through-hole (84) are both located on the outer surface of the housing (1) and are respectively connected to an oil filling hole (11); the other end of the third oil passage through-hole (83) and the other end of the fourth oil passage through-hole (84) are respectively connected to the first sensing chamber and the second sensing chamber.

7. The dual-chip oil-filled differential pressure sensor according to claim 6, wherein An oil filling steel ball (9) is provided in the oil filling hole (11).

8. The oil-filled dual-chip differential pressure sensor according to claim 1, characterized in that, The sensing hydraulic fluid is dimethyl silicone oil; the first oil passage through-hole (81) and the second oil passage through-hole (82) are arranged in parallel.

9. The double-chip oil-filled differential pressure sensor according to claim 1, characterized in that Both the housing (1) and the pressure ring (7) are made of stainless steel; the isolation diaphragm (6) is an integrally formed stainless steel corrugated isolation diaphragm; the housing (1) and the pressure ring (7) are formed by laser welding.

10. The double-chip oil-filled differential pressure sensor according to claim 2, wherein, The package (1), the first conductive pin (21), the second conductive pin (22) and the glass insulator (3) are integrally formed by a sintering and curing process.

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