Pressure sensor

Abstract

A pressure sensor suitable for use at high temperatures, in particular for cylinder pressure measurement, comprising: a tubular housing extending longitudinally front and back; the pressure sensitive element is fixed at the front end of the shell in a closed manner and comprises an elastic membrane extending transversely and a pressure measuring circuit arranged on the inner side surface of the elastic membrane in an insulating manner; the electronic module assembly is fixed in the shell; and an electrical connection assembly electrically connecting the pressure measurement circuit longitudinally to the electronics module assembly.

Description

Technical Field

[0001] This application relates to the field of sensor technology, specifically to a pressure sensor. Background Technology

[0002] In an engine, the temperature inside the cylinder block can reach as high as 300°C. When measuring the cylinder pressure, pressure sensors are typically installed in stepped bores in the cylinder wall. These pressure sensors usually use piezoelectric sensing elements, which requires at least one terminal to be led out from each of the two poles on either side of the piezoelectric element to transmit the generated voltage signal to the electronic module assembly. However, to avoid overheating, the electronic module assembly must be kept away from the pressure sensing element. This makes the electrical connection and sealing between the pressure sensing element and the electronic module assembly difficult to achieve.

[0003] The information disclosed in the background section of this invention is only intended to enhance the understanding of the general background of this invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0004] In view of the shortcomings of the prior art, this application provides a pressure sensor to solve at least one of the above-mentioned defects.

[0005] The present invention provides a pressure sensor comprising: a tubular housing extending longitudinally from front to back; a pressure-sensitive element fixedly in a closed manner at the front end of the housing, including a laterally extending elastic diaphragm and a pressure measuring circuit insulatedly disposed on the inner surface of the elastic diaphragm; an electronic module assembly fixed inside the housing; and an electrical connection assembly that connects the pressure measuring circuit longitudinally to the electronic module assembly.

[0006] Preferably, the electrical connection assembly includes at least two longitudinally extending, straight metal needles, a first conductive helical spring whose front and rear ends are electrically contacted with the pressure measuring circuit and the front end of each metal needle, respectively, and a second conductive helical spring whose front and rear ends are electrically contacted with the rear end of each metal needle and the electronic module assembly, respectively.

[0007] Preferably, the electrical connection assembly further includes a long cylindrical retainer made of insulating material; the metal pin passes through a plurality of retaining holes provided on the retainer, and most of it is circumferentially positioned and held within the corresponding retaining holes.

[0008] Preferably, the pressure sensor further includes a circumferential positioning ring that circumferentially positions the retainer within the housing, and the edge of the pressure-sensitive element is circumferentially fixed and enclosed at the front end of the housing via the circumferential positioning ring.

[0009] Preferably, the pressure sensor further includes a positioning element that is passed through by the metal needle in a front-to-back manner, forming a circumferential positioning with the electronic module assembly.

[0010] Preferably, the electronic module assembly includes a columnar and longitudinally extending main body, a circuit board fixed to a mounting plane formed on one circumferential side of the middle of the main body, and a plurality of elastic electrical connectors molded on the main body; one end of the elastic electrical connector forms a cantilevered contact spring that makes electrical contact with the back of the circuit board; the main body is provided with a clearance hole that suspends the contact spring.

[0011] Preferably, the elastic electrical connector includes at least two first elastic electrical connectors that are electrically connected to the second conductive helical spring; the front end of the main body is provided with a receiving hole corresponding to at least a portion of the second conductive helical spring; the other end of the first elastic electrical connector relative to its contact spring is formed in the receiving hole and correspondingly electrically contacts the electrical contact portion of the second conductive helical spring.

[0012] Preferably, the housing includes a metal portion, and the electronic module assembly includes a second resilient electrical connector; the other end of the second resilient electrical connector relative to its contact spring forms a second contact spring that makes electrical contact with the metal portion.

[0013] Preferably, the pressure sensor further includes a terminal assembly, the terminal assembly including a wire harness sleeve and a plurality of wire harnesses passing through the wire harness sleeve; the resilient electrical connector further includes a third resilient electrical connector, the other end of the third resilient electrical connector relative to its contact spring being electrically connected to the wire harnesses.

[0014] Preferably, the housing includes a front housing, a middle housing, and a rear housing that are sequentially and sealed together; the front housing has a rearward-facing first stop surface, and the rear housing has a forward-facing second stop surface; the first stop surface and the second stop surface respectively fix the electrical connection assembly and the electronic module assembly in a front-to-back position within the housing from the front and rear sides. Attached Figure Description

[0015] Figure 1 This is an exploded view of a pressure sensor according to a preferred embodiment.

[0016] Figure 2 This is a longitudinal sectional view of a pressure sensor according to a preferred embodiment.

[0017] Figure 3 This is a longitudinal sectional view of a pressure-sensitive element according to a preferred embodiment.

[0018] Figure 4 This is a perspective view of a pressure-sensitive element according to a preferred embodiment.

[0019] Figure 5 This is a partial three-dimensional view of an electrical connection assembly according to a preferred embodiment. Detailed Implementation

[0020] The technical solution of this application will now be clearly and completely described with reference to the accompanying drawings. The following embodiments are exemplary and are only used to explain this application, and should not be construed as limiting this application. In the following description, the same reference numerals are used to denote the same or equivalent elements, and repeated descriptions are omitted.

[0021] In the description of this application, it should be understood that the terms "upper," "lower," "inner," "outer," "left," and "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the equipment or component 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 on this application. In addition, the prepositions "first," "second," and "third," etc., are only used for the purpose of distinguishing the modified objects, and should not be construed as indicating or implying relative importance.

[0022] Furthermore, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0023] It should also be further understood that the term "and / or" as used in this application specification and the corresponding claims refers to any combination of one or more of the listed items and all possible combinations.

[0024] like Figures 1-4 As shown. In a preferred embodiment of this application, the pressure sensor 100 includes a housing 1, a pressure-sensitive element 2, an electrical connection assembly 3, and an electronic module assembly 4. The housing 1 is tubular and preferably made of metal, extending longitudinally in the front-rear direction. The pressure-sensitive element 2 is fixed and enclosed at the front end of the housing 1 to receive the pressure to be measured, such as the pressure inside an engine cylinder.

[0025] Specifically, the outer casing 1 comprises a front casing 11, a middle casing 12, and a rear casing 13, which are sequentially and sealed together from front to rear. The rear end 11g of the front casing 11 is welded to the front end 11f of the middle casing 12, and the rear end 12g of the middle casing 12 is welded to the front end 13f of the rear casing 13. In this embodiment, the front casing 11 further comprises a thin segment 111 on the front side and a thick segment 112 on the rear side. A stepped surface 11b facing the front end is formed on the outer wall of the junction of the thin segment 111 and the thick segment 112. The stepped surface 11b is used for positioning when installing with external equipment, for example, in a stepped mounting hole on an engine block. The front side wall of the thin segment 111 may be provided with an external thread 1111 for threaded connection with the mounting hole. Similarly, the rear housing 13 may also include a narrow section 131 on the front side and a thick section 132 on the rear side, wherein an annular groove 13b facing the front side is formed on the outer wall of the joint between the narrow section 131 and the thick section 132 for mounting a sealing ring 139, thereby sealing with the mounting hole.

[0026] Preferably, a rearward-facing stop surface 11a is formed on the inner wall of the connection between the thin segment 111 and the thick segment 112, and a frontward-facing stop surface 13a is formed on the inner wall of the connection between the thin segment 131 and the thick segment 132. The stop surfaces 11a and 13a respectively fix the electrical connection assembly 3 and the electronic module assembly 4 in a front-rear positioning manner within the housing 1 from the front and rear sides.

[0027] Please refer to the following for details. Figure 3 , Figure 4 The pressure-sensitive element 2 may include a laterally extending elastic diaphragm 20 and a pressure measuring circuit 23 insulated on the inner surface of the elastic diaphragm 20. Specifically, the pressure measuring circuit 23 may be a piezoresistive pressure measuring circuit, for example, the pressure measuring circuit 23 may include a Wheatstone bridge composed of four piezoresistors 230 and printed circuitry 232. Preferably, the elastic diaphragm 20 is a metal component for easy machining, such as a stainless steel component, and its inner surface has an insulating layer 22 printed on it as the basis of the pressure measuring circuit 23. The piezoresistors 230 may be thick-film resistors made using thick-film technology. In some other embodiments, the elastic diaphragm 20 may also be a ceramic component, in which case the insulating layer 22 may be omitted.

[0028] The electrical connection assembly 3 and the electronic module assembly 4 are fixed inside the housing 1 with a gap between them. The electronic module assembly 4 is located far behind the electrical connection assembly 3 to avoid damage from the pressure-sensitive element 2 due to high temperature at the front end. The pressure measurement circuit 23 is longitudinally connected to the electronic module assembly 4 through the electrical connection assembly 3.

[0029] Preferably, in order to enable the electrical connection assembly 3 to connect the electronic module assembly 4 to the pressure measuring circuit 23 at a considerable rearward distance, the electrical connection assembly 3 may include at least two longitudinally extending metal needles 31, conductive helical springs 32 with their front and rear ends electrically contacting the pressure measuring circuit 23 and the front end of each metal needle 31, respectively, and conductive helical springs 33 with their front and rear ends electrically contacting the rear end of each metal needle 31 and the electronic module assembly 4, respectively. More preferably, the metal needles 31 are long and straight; more specifically, the aspect ratio of their main body, which occupies most of the longitudinal length, is preferably 50 or more, thereby keeping the electronic module assembly 4 as far away from the heat source center as possible while maintaining a limited outer diameter.

[0030] Preferably, the electrical connection assembly 3 may further include a long, cylindrical retainer 34 made of an insulating material (e.g., ceramic or high-temperature resistant plastic). The metal needle 31 passes through a plurality of retaining holes 34a provided on the retainer 34, and the outer diameter of its main body portion is adapted to the inner diameter of the corresponding retaining hole 34a to restrict circumferential relative rotation, thereby circumferentially positioning and retaining the metal needle 31 within the corresponding retaining hole 34a. Preferably, the retainer 34 is a stepped shaft shape, which may include a main body portion 341 and an enlarged portion 342 formed by expanding the rear end of the main body portion 341. A forward-facing stepped surface 34b is formed at the connection between the main body portion 341 and the enlarged portion 342, and the stepped surface 34b abuts forward against the stop surface 11a.

[0031] Preferably, the pressure sensor 100 further includes a circumferential positioning ring 6. The circumferential positioning ring 6 is used to circumferentially position the retainer 34 within the housing 1. Specifically, the circumferential positioning ring 6 can be a metal component, comprising a ring body 61. The rear end of the ring body 61 is coaxially welded to the front end 11f of the thin segment 111, and its front end can be coaxially and sealingly welded to the edge of the rear end face of the pressure-sensitive element 2. The inner edge of the ring body 61 can be integrally connected to two circumferentially spaced circumferential positioning posts 62. The front end 62f of the circumferential positioning post 62 faces forward to form a circumferential positioning with the pressure-sensitive element 2, and the rear end 62g of the circumferential positioning post 62 faces backward to form a circumferential positioning with the retainer 34. Preferably, the edge of the pressure measuring circuit 23 protrudes forward to form a flange 21, and the front side of the elastic diaphragm 20 correspondingly forms a cavity 2a between itself and the inner wall of the flange 21. The rear end face of the flange 21 is provided with two circumferentially spaced positioning holes 21a to correspondingly receive the front ends 62f of the two circumferential positioning posts 62, thereby forming a circumferential positioning between the pressure sensitive element 2 and the circumferential positioning ring 6; two circumferentially spaced positioning grooves 341a are formed on the outer side wall of the front end of the main body 341 to correspondingly receive the rear ends 62g of the two circumferential positioning posts 62, thereby forming a circumferential positioning between the circumferential positioning ring 6 and the retaining seat 34.

[0032] The electronic module assembly 4 includes a generally columnar main body 41 and a circuit board 40 fixed to the main body 41. Similarly, the main body 41 and the electrical connection assembly 3 are circumferentially positioned. Preferably, the electrical connection assembly 3 may also include a positioning member 35, which has multiple through holes 35a for the metal pin 31 to pass through in a corresponding front-to-back fit. Thus, the positioning member 35 and the metal pin 31 are circumferentially positioned. Two circumferentially spaced positioning grooves 35b are formed on its outer wall. The front end of the electronic module assembly 4 protrudes forward to form two circumferentially spaced circumferential positioning portions 412, which fit into the corresponding positioning grooves 35b, thereby forming circumferential positioning between the electrical connection assembly 3 and the electronic module assembly 4. The positioning grooves 35b extend rearward to the rear end center of the positioning member 35. Preferably, the positioning grooves 35b extend forward to the front end face of the positioning member 35, and the circumferential positioning portions 412 are leg-shaped.

[0033] Preferably, the circuit board 40 is housed within a notch 41a formed on the outer peripheral sidewall of the main body 41, and its back side is fixed to a mounting plane 41b formed between the notches 41a, and is riveted to the main body 41 by a plurality of hot riveting posts 411 protruding from the mounting plane 41b. The front side of the circuit board 40 is provided with a processing circuit that may include a conditioning element 401. The electronic module assembly 4 also includes a plurality of elastic electrical connectors 42-44 molded on the main body 41, one end of which forms a cantilevered contact spring 422, 432, 442 that makes electrical contact with the back side of the circuit board 40. The main body 41 may be provided with a plurality of clearance holes 41c to allow the contact springs 422, 432, 442 to be suspended, so as to allow the corresponding contact springs 422, 432, 442 to elastically deform and make way.

[0034] Specifically, there are at least two flexible electrical connectors 42. The middle portion 420 is molded and enclosed within the main body 41. Its front end forms a laterally extending plate-shaped electrical contact portion 421 for forward electrical contact with the corresponding conductive coil spring 33. Its rear end forms a contact spring 422 for electrical contact with the back of the circuit board 40. The front end of the main body 41 is provided with a receiving hole 41d corresponding to at least a portion of the conductive coil spring 33. The other end of the flexible electrical connector 42, relative to its contact spring 422, is formed within the receiving hole 41d and corresponding to the electrical contact portion 421 of the conductive coil spring 33.

[0035] There are at least two flexible electrical connectors 43, the middle part 430 of which is molded inside the main body part 41, the rear end of which can extend outward longitudinally to form a welding part 431, and the front end of which forms a contact spring 432 that makes electrical contact with the back of the circuit board 40.

[0036] At least one flexible electrical connector 44 is provided, with its middle portion 440 molded inside the main body 41. Its rear end can form a contact spring 442 electrically contacting the back of the circuit board 40, and its front end can form a contact spring 422 electrically contacting the inner wall of the middle housing 12. In this way, the middle housing 12 can be electrically connected to the ground terminal of the circuit board 40 via the aforementioned flexible electrical connector 44, thereby enhancing its electromagnetic shielding performance against external electromagnetic interference.

[0037] In some other embodiments, the pressure sensor 100 may also include a terminal assembly 5 that forms an electrical connection with an external device. The terminal assembly 5 may include a plurality of wire harnesses 51. One inner end of each wire harness 51 may be welded to a welding portion 431 of the elastic electrical connector 43. Preferably, the terminal assembly 5 may include a wire harness sleeve 53 having a plurality of through holes 53a that allow the wire harnesses 51 to pass through. The front end of the wire harness sleeve 53 abuts against the rear end of the main body 41, and an elastic washer 531 may be provided between the rear end of the wire harness sleeve 53 and the stop surface 13a. Thus, the enlargement 342, the positioning member 35, the main body 41, the wire harness sleeve 53, and the elastic washer 531 are sequentially fixed from front to back between the stop surface 11a and the stop surface 13a. In some other embodiments, the elastic washer 531 may also change its front and rear positions accordingly.

[0038] The terminal assembly 5 may further include a plug 52 connected to the outer end of the wire harness 51. The plug 52 may be sealed at the rear end of the rear housing 13. For example, an internal thread 1321 may be formed on the inner wall of the rear end of the rear housing 13, and a matching external thread 52d may be formed on the outer wall of the front portion of the plug 52.

[0039] In the above embodiments, the positioning member 35 can be directly fixed to a suitable axial position on the metal needle 31 by molding, so as to form a shape together with the metal needle 31 as shown in the figure. Figure 5 The components are shown. One end of the metal needle 31 can form a front needle tip 31f that is inserted into the conductive coil spring 32, and the other end can form a rear needle tip 31g that is inserted into the coil spring 33. The front needle tip 31f can be tightly fitted with the metal needle 31 to facilitate the assembly of the conductive coil spring 32.

[0040] It is easy to understand that the basic shape of some of the above components, such as housing 1, retainer 34, positioning element 35, main body 41, wire harness sleeve 53, metal needle 31, pressure sensitive element 2, and ring body 61, can be circular or annular, or other suitable shapes.

[0041] The scope of this disclosure is not limited by the detailed description, but by the claims and their equivalents, and all variations within the scope of the claims and their equivalents are to be included in this disclosure.

Claims

1. A pressure sensor (100), characterized in that, include: A tubular housing (1) extending longitudinally from front to back; a pressure-sensitive element (2) that is closedly fixed at the front end of the housing (1), including a laterally extending elastic diaphragm (20) and a pressure measuring circuit (23) insulatedly disposed on the inner surface of the elastic diaphragm (20); an electronic module assembly (4) fixed inside the housing (1); and an electrical connection assembly (3) that makes the pressure measuring circuit (23) longitudinally electrically connected to the electronic module assembly (4).

2. The pressure sensor (100) according to claim 1, characterized in that, The electrical connection assembly (3) includes at least two longitudinally extending, straight metal needles (31), a first conductive helical spring (32) whose front and rear ends are electrically contacted with the pressure measuring circuit (23) and the front end of each metal needle (31), respectively, and a second conductive helical spring (33) whose front and rear ends are electrically contacted with the rear end of each metal needle (31) and the electronic module assembly (4), respectively.

3. The pressure sensor (100) according to claim 2, characterized in that, The electrical connection assembly (3) further includes a long columnar retainer (34) made of insulating material; the metal needle (31) passes through a plurality of retaining holes (34a) provided on the retainer (34) in the front and back respectively, and most of it is circumferentially positioned and held in the corresponding retaining hole (34a).

4. The pressure sensor (100) according to claim 3, characterized in that, It also includes a circumferential positioning ring (6) that circumferentially positions the retainer (34) within the housing (1), and the edge of the pressure-sensitive element (2) is circumferentially fixed and enclosed at the front end of the housing (1) by the circumferential positioning ring (6).

5. The pressure sensor (100) according to claim 2, characterized in that, It also includes a positioning element (35) that is passed through by the metal needle (31) in a front-to-back manner, which forms a circumferential positioning with the electronic module assembly (4).

6. The pressure sensor (100) according to claim 2, characterized in that, The electronic module assembly (4) includes a columnar and longitudinally extending main body (41), a circuit board (40) fixed to a mounting plane (41b) formed on one circumferential side of the middle part of the main body (41), and a plurality of elastic electrical connectors molded on the main body (41); one end of the elastic electrical connector forms a cantilevered contact spring that makes electrical contact with the back of the circuit board (40); the main body (41) is provided with a clearance hole (41c) to suspend the contact spring.

7. The pressure sensor (100) according to claim 6, characterized in that, The elastic electrical connector includes at least two first elastic electrical connectors (42) that are electrically connected to the second conductive helical spring (33); the front end of the main body (41) is provided with a receiving hole (41d) that corresponds to accommodating at least a portion of the second conductive helical spring (33); the other end of the first elastic electrical connector (42) relative to its contact spring is formed in the receiving hole (41d) and is electrically contacted to the electrical contact portion (421) of the second conductive helical spring (33).

8. The pressure sensor (100) according to claim 6, characterized in that, The housing (1) includes a metal portion, and the electronic module assembly (4) includes a second elastic electrical connector (44); the other end of the second elastic electrical connector (44) relative to its contact spring forms a second contact spring (441) that makes electrical contact with the metal portion.

9. The pressure sensor (100) according to claim 6, characterized in that, It also includes a terminal assembly (5), which includes a wire harness sleeve (53) and a plurality of wire harnesses (51) passing through the wire harness sleeve (53); the resilient electrical connector also includes a third resilient electrical connector (43), the other end of which relative to its contact spring is electrically connected to the wire harnesses (51).

10. The pressure sensor (100) according to any one of claims 1 to 9, characterized in that, The outer casing (1) includes a front casing (11), a middle casing (12), and a rear casing (13) that are sequentially sealed together; the front casing (11) has a rearward first stop surface (11a), and the rear casing (13) has a forward second stop surface (13a); the first stop surface (11a) and the second stop surface (13a) respectively fix the electrical connection assembly (3) and the electronic module assembly (4) in the outer casing (1) from the front and rear sides.

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