Piezoelectric pressure sensors and their manufacturing methods, internal combustion engines

Abstract

This invention provides a piezoelectric pressure sensor, a manufacturing method thereof, and an internal combustion engine. The piezoelectric pressure sensor includes: a diaphragm element, a piezoelectric element, a transition element axially located between the diaphragm element and the piezoelectric element; a clamping element axially adjacent to the piezoelectric element, the transition element axially located on a first side of the piezoelectric element, and the clamping element axially located on a second side of the piezoelectric element; and a pre-tightening sleeve, the space defined by the radial inner wall of the pre-tightening sleeve providing a first chamber, at least a portion of the transition element, the clamping element, and the piezoelectric element being located in the first chamber; wherein the radial inner wall of the pre-tightening sleeve abuts against the radial outer walls of the transition element and the clamping element, and the radial outer wall of the piezoelectric element has a radial gap with the radial inner wall of the pre-tightening sleeve.

Description

Technical Field

[0001] This invention relates to piezoelectric pressure sensors and their manufacturing methods, and internal combustion engines. Background Technology

[0002] In recent years, with increasingly stringent global requirements for ship emissions and a stronger demand for fuel efficiency, the development of a fully closed-loop in-cylinder combustion system is crucial for diesel engines to achieve consistent cylinder combustion, reduce emissions, and improve fuel economy. Accurate, real-time detection of in-cylinder combustion pressure using cylinder pressure sensors allows for control of fuel injection quantity and timing, thereby controlling the combustion process and improving engine efficiency. However, cylinder pressure sensors typically operate at high temperatures (around 350°C), high pressures (around 35 MPa), and high frequencies (around 50 Hz), while also requiring very high reliability (typically a mean time to failure (MTTF) of 8000 hours).

[0003] Currently, the main measurement principles of cylinder pressure sensors are piezoresistive and piezoelectric. Piezoresistive pressure sensors are based on the piezoresistive effect; when a silicon-based semiconductor senses external mechanical stress, the semiconductor's geometry and conductivity change accordingly, resulting in a change in the semiconductor material's resistance. This change in resistance is proportional to the applied external pressure and is generally suitable for environments where static and quasi-static pressure are tested.

[0004] Piezoelectric pressure sensors are based on the piezoelectric effect. When a piezoelectric crystal senses external pressure, it generates an electric charge signal on its surface that is proportional to the magnitude of the measured pressure. They are suitable for measuring pressure signals with extremely short rise times and can also measure dynamic pressures with minimal changes under high static pressure. Cylinder pressure sensors are primarily used for long-term measurement of cylinder pressure during combustion in diesel engines and other motors. Piezoelectric pressure sensors are more suitable than piezoresistive pressure sensors for high-temperature, high-pressure cylinder pressure testing environments.

[0005] However, the inventors discovered that the accuracy of piezoelectric pressure sensors still needs further improvement in high-temperature environments. Summary of the Invention

[0006] The purpose of this invention is to provide a piezoelectric pressure sensor.

[0007] Another object of the present invention is to provide a method for manufacturing a piezoelectric pressure sensor.

[0008] Another object of the present invention is to provide an internal combustion engine.

[0009] According to a first aspect of the present invention, a piezoelectric pressure sensor includes a diaphragm element located at an axial end of the sensor for acquiring a measured pressure; a piezoelectric element capable of generating an electric charge signal based on the acquired measured pressure; a transition element located axially between the diaphragm element and the piezoelectric element; a clamping element adjacent to the piezoelectric element in the axial direction, the transition element located axially on a first side of the piezoelectric element, the clamping element located axially on a second side of the piezoelectric element, the first side and the second side being disposed opposite to each other; and a pre-tightening sleeve, the space defined by the radial inner wall of the pre-tightening sleeve providing a first chamber, at least a portion of the transition element, the clamping element, and the piezoelectric element being located in the first chamber; wherein the radial inner wall of the pre-tightening sleeve abuts against the radial outer walls of the transition element and the clamping element, and the radial outer wall of the piezoelectric element and the radial inner wall of the pre-tightening sleeve have a radial gap.

[0010] The technical solutions described in the above embodiments improve the accuracy of piezoelectric pressure sensors. The principle behind this is that the inventors discovered that, under high-temperature conditions, one of the main reasons affecting accuracy is that the crystal sheet is easily deformed by temperature changes, thus affecting the overall sensor accuracy. The above technical solution, through the synergistic action of the clamping element, transition element, and pre-tightening sleeve, ensures the stable installation and fixation of the piezoelectric element. Furthermore, in the formed installation and fixing structure, the radial outer wall of the piezoelectric element and the radial inner wall of the pre-tightening sleeve have a radial gap, creating an air insulation layer between the piezoelectric element and the structures on both sides, thus minimizing changes in detection accuracy caused by micro-deformation of the crystal sheet.

[0011] In one or more embodiments of the pressure sensor, a heat-insulating gasket is provided between the transition element and the piezoelectric element.

[0012] In one or more embodiments of the pressure sensor, the piezoelectric element comprises an X0-cut lanthanum gallium silicate crystal with a sheet-like structure.

[0013] In one or more embodiments of the pressure sensor, the diaphragm element includes a diaphragm body and an extension, the diaphragm body providing an action surface for acquiring the measured pressure, the extension extending axially from the diaphragm body, and the diaphragm body extension being fixedly connected to the transition element.

[0014] In one or more embodiments of the pressure sensor, the sensor further includes a pre-tightening element fixedly connected to the clamping element on a second side adjacent to the clamping element; the sensor further includes a first housing, the space defined by the radial inner wall of the first housing providing a second chamber, the pre-tightening sleeve being located in the second chamber, and the diaphragm body and the pre-tightening element being fixedly connected to the first housing at axial ends of the first housing, respectively.

[0015] In one or more embodiments of the pressure sensor, the first housing includes a first housing body and a flange extending radially outward from the first housing body. The sensor also includes a second housing, the space defined by the radial inner wall of the second housing providing a third chamber, the first housing body being located in the third chamber, one axial end of the second housing being fixedly connected to the flange, and the other axial end being fixedly connected to a cover, such that the cover and the diaphragm body close the third chamber at both axial ends.

[0016] In one or more embodiments of the pressure sensor, the outer wall of the second housing has external threads, and the second housing is separated from the preload sleeve by the first housing.

[0017] In one or more embodiments of the pressure sensor, the piezoelectric element is respectively connected to a first conductive element and a second conductive element disposed opposite to each other; the transition element and the clamping element respectively have a first wire hole and a second wire hole penetrating their axial thickness; the first wire passes through the first wire hole and is connected to the first conductive element, and the second wire passes through the second wire hole and is connected to the second conductive element.

[0018] An internal combustion engine according to a second aspect of the present invention includes a piezoelectric pressure sensor as described in the first aspect and a cylinder, the sensor being disposed in the cylinder for measuring the cylinder pressure.

[0019] The beneficial effect is that, due to the use of the sensor described in the first aspect, the cylinder pressure can be accurately and in real time detected, thereby forming a cylinder combustion system with a completely closed-loop combustion process. This enables the consistency of cylinder combustion in internal combustion engines, especially marine diesel engines, reducing emissions and improving fuel economy.

[0020] According to a third aspect of the present invention, a method for manufacturing a piezoelectric pressure sensor employs the piezoelectric pressure sensor as described in the first aspect, the manufacturing method comprising:

[0021] The transition element, piezoelectric element, and clamping element are stacked axially; a preload is applied to the transition element and clamping element so that the transition element and clamping element press the piezoelectric element on both sides of the axial direction; a preload sleeve is fitted around the radial periphery of the transition element, piezoelectric element, and clamping element, with one end of the preload sleeve fixedly connected to the clamping element in the axial direction and the other end fixedly connected to the transition element in the axial direction.

[0022] The above is a manufacturing method described in the embodiments. Its manufacturing process is simple and easy to implement. Attached Figure Description

[0023] The above and other features, properties, and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, in which the same reference numerals always denote the same features. It should be noted that these drawings are merely illustrative and are not drawn to scale, and should not be construed as limiting the scope of protection actually claimed by the present invention, wherein:

[0024] Figure 1 This is a schematic diagram of the structure of a pressure sensor according to one embodiment;

[0025] Figure 2 for Figure 1 A schematic diagram of the pre-tightening sleeve of the pressure sensor;

[0026] Figures 3A to 3D This is a schematic diagram of the assembly structure of a pressure sensor according to one embodiment.

[0027] Figure label:

[0028] 100-Piezoelectric pressure sensor;

[0029] 1-Diaphragm element, 11-Diaphragm body, 12-Extension, 121-Weld;

[0030] 2-Piezoelectric element, 20-Conductive element, 21-First conductive element, 22-Second conductive element, 211-First wire, 221-Second wire;

[0031] 3-Transition element, 30-Insulation pad, 31-First wire hole;

[0032] 4-Clamping element; 41-Second wire hole;

[0033] 5-Pre-tightening sleeve, 50-First chamber, 51, 52-Welds;

[0034] 6-Preload element, 61-Weld;

[0035] 7-First shell, 70-Second chamber, 71-First shell body, 711-Weld, 72-Flange, 721-Weld;

[0036] 8-Second shell, 80-Second chamber, 81-External thread, 82, 83-Weld;

[0037] 9-Lid;

[0038] 10 - Socket insert; 101 - Socket core;

[0039] G - Radial clearance. Detailed Implementation

[0040] Reference will now be made in detail to various embodiments of the invention, examples of which are shown in the accompanying drawings and described below. Although the invention will be described in conjunction with exemplary embodiments, it should be understood that this specification is not intended to limit the invention to those exemplary embodiments. Rather, the invention is intended to cover not only these exemplary embodiments, but also various alternatives, modifications, equivalents, and other embodiments that may be included within the spirit and scope of the invention as defined by the appended claims.

[0041] Furthermore, this application uses specific terms to describe its embodiments. For example, "an embodiment" and / or "one embodiment" refers to a particular feature, structure, or characteristic associated with at least one embodiment of this application. Therefore, it should be emphasized and noted that "an embodiment" or "one embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application can be appropriately combined.

[0042] Currently, with the increasing emission requirements for internal combustion engines, it is necessary to measure the cylinder pressure of internal combustion engines operating at high temperatures in real time and with high accuracy. Therefore, the cylinder pressure sensor generally adopts a piezoelectric pressure sensor suitable for working in high temperature and high pressure environments.

[0043] Through in-depth research, the inventors of this application discovered that the accuracy of piezoelectric pressure sensors needs further improvement, especially in high-temperature environments. The inventors found that, under high-temperature conditions (operating temperature around 350℃), one of the main reasons affecting accuracy is that the crystal wafer is easily affected by temperature changes, resulting in micro-deformation and thus impacting the overall sensor accuracy.

[0044] Based on the above considerations, the inventors, after in-depth research, designed a piezoelectric pressure sensor. Through the synergistic action of the clamping element, the transition element, and the pre-tightening sleeve, the piezoelectric element is stably installed and fixed. In the formed installation and fixing structure, there is a radial gap between the radial outer wall of the piezoelectric element and the radial inner wall of the pre-tightening sleeve, so that the piezoelectric element and the structures on both sides form an air insulation layer to minimize the problem of changes in detection accuracy caused by micro-deformation of the crystal sheet.

[0045] Although the piezoelectric pressure sensor disclosed in this application is exemplified as a cylinder pressure sensor for marine diesel engine cylinders, with the sensor installed in the cylinder to measure the cylinder pressure to reduce emissions and improve fuel economy, it is not limited thereto. For example, it can be used in other applications where the accuracy of the piezoelectric pressure sensor needs to be guaranteed under high-temperature conditions.

[0046] refer to Figure 1 As shown, in some embodiments, the piezoelectric pressure sensor 100 includes: a diaphragm element 1, a piezoelectric element 2, a transition element 3, a clamping element 4, and a pre-tightening sleeve 5.

[0047] Diaphragm element 1 is located at the axial end of sensor 100 and is used to acquire the measured pressure. The effective area of ​​diaphragm element 1 converts the measured pressure into a force proportional to the measured pressure acting on the piezoelectric element. This force generates a stress on the piezoelectric element 2, thereby causing the piezoelectric element 2 to generate a charge proportional to the measured pressure, thus realizing the sensing of the cylinder pressure.

[0048] The piezoelectric element 2 is capable of generating an electric charge signal based on the measured pressure. The material of the piezoelectric element 2 is generally a crystal exhibiting piezoelectric effect, such as quartz (SiO2 single crystal) or calcium gallium germanate (Ca3Ga2Ge4O3). 14 Or CGG), lanthanum gallium silicate (La3Ga5SiO) 14 Materials include LGS (or LGS), tourmaline, gallium phosphate, piezoelectric ceramics, etc. Preferably, in some embodiments, the piezoelectric crystal of the piezoelectric element 2 is a sheet-like X0-cut lanthanum gallium silicate crystal. Here, X0 cutting is what is commonly referred to in the art as X-cutting. The inventors have discovered that by selecting a lanthanum gallium silicate crystal and obtaining a piezoelectric crystal in the X-cutting direction, the tangential direction, which is sensitive to pressure measurement but insensitive to temperature, is obtained, thus maintaining both high charge sensitivity and stable temperature stability, resulting in better measurement accuracy.

[0049] The transition element 3 is located axially between the diaphragm element 1 and the piezoelectric element 2. Its function is to uniformly distribute the force collected by the diaphragm element 1 onto the piezoelectric element 2. Therefore, the transition element 3 is generally conductive and possesses a certain degree of rigidity. The transition element 3 contacts the diaphragm element 1 on one side and the piezoelectric element 2 on the other side, and the contact surfaces of the transition element 3 and the piezoelectric element 2 need to maintain tight contact. Preferably, the outer diameter of the transition element 3 and the piezoelectric element 2 are consistent to ensure measurement sensitivity. It can be understood that the thickness of the transition element 3 needs to meet its rigidity requirements and can be set according to the specific sensor size.

[0050] The clamping element 4 is axially adjacent to the piezoelectric element 2. The transition element 3 is axially located on the first side of the piezoelectric element 2, and the clamping element 4 is axially located on the second side of the piezoelectric element 2. The first and second sides are arranged opposite to each other. For example, if the axial direction in the figure is vertical, then the transition element 3 is located on the lower side of the piezoelectric element, and the clamping element 4 is located on the upper side of the piezoelectric element. The function of the clamping element 4 is to clamp the piezoelectric element 2 so that its contact surface with the transition element 3 is tightly fitted.

[0051] refer to Figure 1 as well as Figure 2 As shown, the space defined by the radial inner wall of the preload sleeve 5 provides a first chamber 50, in which at least a portion of the transition element 3, the clamping element 4, and the piezoelectric element 2 are located. The function of the preload sleeve 5 is to hold the piezoelectric element 3 within the sensor cavity, and to maintain a certain preload on the piezoelectric element 2 by the transition element 3 and the clamping element 4 to ensure that the sensor has good linearity and stable sensitivity throughout its operating range. Preferably, in some embodiments, the wall thickness of the preload sleeve 5 is generally thin to provide a certain degree of elasticity, and the wall thickness is less than 0.2 mm.

[0052] Continue to refer to Figure 1 As shown, the radial inner wall of the pre-tightening sleeve 5 is tightly pressed against the radial outer wall of the transition element 3 and the clamping element 4, and the radial outer wall of the piezoelectric element 2 has a radial gap G with the radial inner wall of the pre-tightening sleeve 5. The beneficial effect of the above-described embodiment is that, through the synergistic action of the clamping element 4, the transition element 3, and the pre-tightening sleeve 5, the piezoelectric element 2 is stably installed and fixed. Furthermore, in the formed installation and fixing structure, the radial outer wall of the piezoelectric element 2 has a radial gap with the radial inner wall of the pre-tightening sleeve 5, so that the piezoelectric element 2 and the structures on both sides form an air insulation layer, thereby minimizing the problem of changes in detection accuracy caused by micro-deformation of the crystal sheet.

[0053] Continue to refer to Figure 1As shown, in some embodiments, a heat-insulating pad 30 is provided between the transition element 3 and the piezoelectric element 2. It can be understood that the function of this heat-insulating pad is heat insulation, further reducing the influence of heat transferred from the diaphragm element 1 on the piezoelectric element 2, thereby improving measurement accuracy. The material of the heat-insulating pad is generally a material with a thermal conductivity lower than that of the transition element 3 and the pre-tightening sleeve 5. Structurally, the contact surfaces of the heat-insulating pad with the piezoelectric element 2 and the transition element 3 generally need to be tightly fitted, and their outer diameters should be consistent with the outer diameters of the transition element 3 and the piezoelectric element 2 to ensure measurement sensitivity.

[0054] Continue to refer to Figure 1 as well as Figures 3A to 3D As shown, in some embodiments, the diaphragm element 1 may also include a diaphragm body 11 and an extension 12. The diaphragm body 11 provides an action surface for collecting the measured pressure, and the extension 12 extends axially from the diaphragm body 11. The diaphragm body extension 12 is fixedly connected to the transition element 3. Preferably, the sensor 100 may further include a first housing 7. The space defined by the radial inner wall of the first housing 7 provides a second chamber 70. The pre-tightening sleeve 5 is located in the second chamber 70, and the diaphragm body 11 is fixedly connected to the first housing 7 at its axial end. The fixed connection structure may be a welded connection structure, and the welding process may be laser welding, but this is not a limitation. The beneficial effect of this is that it can further improve the service life and measurement accuracy of the sensor. The principle is that the inventors discovered that when measuring the cylinder pressure of a burning engine, the sensor is subjected to periodic instantaneous thermal shocks. Transient thermal shock can cause changes in sensor sensitivity and zero-point drift. By fixing the diaphragm element 1 to the housing, for example by welding it into a single unit, the effects of transient thermal shock can be effectively reduced, thereby improving service life and measurement accuracy.

[0055] Continue to refer to Figure 1 as well as Figures 3A to 3DAs shown, in some embodiments, the structure of the sensor 100 may further include a pre-tightening element 6, which is fixedly connected to the clamping element 4 adjacent to the clamping element 4 on the second side. The pre-tightening element 6 is fixedly connected to the first housing 7 at the other end of the first housing 7 in the axial direction, that is, the diaphragm body 11 is short-circuited at one end of the first housing 7 in the axial direction. This allows the piezoelectric element 2 to be installed and fixed more stably. Preferably, in some embodiments, the first housing 7 includes a first housing body 71 and a flange 72 extending radially outward from the first housing body 71. The sensor 100 also includes a second housing 8, the space defined by the radial inner wall of which provides a third chamber 80. The first housing body 71 is located in the third chamber 80. The flange 72 is fixedly connected to one end of the second housing 8 in the axial direction, and the cover 9 is fixedly connected to the other end in the axial direction, so that the cover 9 and the diaphragm body 11 close the third chamber 80 at both ends in the axial direction. This allows the second housing 8 to form the outer shell of the sensor 100. The preload sleeve 5 and the outer shell of the sensor 100 are structurally separated by the first housing 7, reducing the impact of external forces caused by non-sensing cylinder pressure on the piezoelectric element 2 and improving the accuracy of sensor measurements. For example, in some embodiments, the sensor 100 is installed via threaded mounting. The outer wall of the second housing 8, which serves as the outer shell, has external threads 81. Torque needs to be applied during installation, and the preload sleeve 5 and the outer shell of the sensor 100 are structurally separated by the first housing 7, making the strain generated by the installation torque have little impact on the sensor output. Furthermore, by applying different torque values ​​to the sensor, the signal change in the quasi-static state of the sensor can be monitored, thereby obtaining the safe range of the installation torque. It can be understood that the specific dimensions of the external thread 81 match the corresponding mounting hole. For example, if the mounting hole is an M10×1 threaded hole, then the size of the external thread 81 is also a corresponding M10×1 thread.

[0056] Continue to refer to Figure 1 as well as Figures 3A to 3D As shown, in some embodiments, the structure of the sensing signal output by the sensor 100 may be such that the piezoelectric element 2 is connected to the conductive element 20, specifically, it is connected to the first conductive element 21 and the second conductive element 22 respectively, which are arranged opposite to each other; the transition element 3 and the clamping element 4 respectively have a first wire hole 31 and a second wire hole penetrating their axial thickness.

[0057] 41; The first wire 211 passes through the first wire hole 31 and connects to the first conductive element 21, and the second wire 221 passes through the second wire hole 41 and connects to the second conductive element 22. The specific structure of the first conductive element 21 and the second conductive element 22 can be a conductive sheet, the first wire 211 can be a signal output line, and the second wire 221 can be a signal ground line.

[0058] refer to Figures 3A to 3D As shown, in some embodiments, the assembly steps for manufacturing sensor 100 may be:

[0059] First, such as Figure 3A Shown:

[0060] Transition element 3, piezoelectric element 2, and clamping element 4 are arranged in an axially stacked manner;

[0061] Apply preload to transition element 3 and clamping element 4 so that transition element 3 and clamping element 4 press piezoelectric element 2 on both sides of the axial direction;

[0062] The pre-tightening sleeve 5 is fitted onto the radial periphery of the transition element 3, the piezoelectric element 2, and the clamping element 4. The pre-tightening sleeve 5 is fixedly connected to the clamping element 4 at one end in the axial direction and to the transition element 3 at the other end in the axial direction.

[0063] During assembly, a dedicated positioning fixture can be used to ensure that the piezoelectric element 2 is centered. If signals are transmitted via the first conductive element 21 and the second conductive element 22, these elements must also be centered. Additionally, it is crucial to ensure that the piezoelectric element 2 and the pre-tightening sleeve 5 are not in contact, thus ensuring the formation of the heat-insulating cavity. A pre-tightening fixture can be used to provide a 500N pre-pressure between the transition element 3 and the clamping element 4, ensuring tight contact between the transition element 3, the clamping element 4, and the piezoelectric element 2. For the fixed structure where the pre-tightening sleeve 5 is fixedly connected to the clamping element 4 at one axial end and to the transition element 3 at the other axial end, such as… Figure 3A As shown, a laser-welded structure can be used. The pre-tightening sleeve 5 is fixedly connected to the clamping element 4 at one axial end via weld 51, and fixedly connected to the transition element 3 at the other axial end via weld 52. During welding, it is necessary to ensure that the laser welding parameters are accurate and the insulation must meet a value of 1000MΩ or higher.

[0064] Finish Figure 3A The steps shown are as follows Figure 3A The component is called the sensitive part 102 of the sensor, referenced. Figure 3B Shown:

[0065] The pre-tightening element 6 and the diaphragm element 1 are axially connected and fixedly connected at the sensitive part. The fixed connection can be achieved by laser welding. The pre-tightening element 6 is fixedly connected to the clamping element 4 through weld 61, and the extension 12 of the diaphragm element 1 is fixedly connected to the transition element 3 through weld 121.

[0066] End as Figure 3B The component obtained after the steps shown is called the first intermediate component, and the first housing 7 is fixedly connected to the first intermediate component. The fixed connection structure can adopt a laser-welded weld structure. For example... Figure 3CAs shown, the first housing 7 is connected to the pre-tightening element 6 via a weld 711 at one axial end of the inner wall of the first housing body 71, and is connected to the diaphragm body 11 of the diaphragm element 1 via a weld 721 at the other axial end of the first housing 7 at the flange 72.

[0067] End as Figure 3C The component obtained after the steps shown is called the second intermediate component. The second housing 8 is fixedly connected to the second intermediate component, and the cover 9 and socket liner 10 are installed accordingly. Similar to the steps described above, a laser-welded weld structure can also be used for fixed connection. The second housing 8 is fixedly connected to the cover 9 at one axial end by weld 82, and to the back of the flange 72 of the first housing 7 at the other axial end by weld 83. Finally, the insert 101 is connected to the first wire 211 to ensure reliable electrical connection. Finally, the overall cable is connected, and the overall cable connection is welded and fixed.

[0068] In summary, the piezoelectric pressure sensor and its manufacturing method, as well as the internal combustion engine described in the above embodiments, offer beneficial effects including, but not limited to, the stable installation and fixation of the piezoelectric element through the synergistic action of the clamping element, transition element, and pre-tightening sleeve. Furthermore, in the formed installation and fixing structure, the radial outer wall of the piezoelectric element and the radial inner wall of the pre-tightening sleeve have a radial gap, creating an air insulation layer between the piezoelectric element and the structures on both sides. This minimizes the problem of changes in detection accuracy caused by micro-deformation of the crystal sheet, achieving consistent cylinder combustion in internal combustion engines, especially marine diesel engines, reducing emissions and improving fuel economy. Additionally, the sensor's manufacturing process is simple and easy to implement.

[0069] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the invention, fall within the protection scope defined by the claims of the present invention.

Claims

1. A piezoelectric pressure sensor (100), characterized in that, include: A diaphragm element (1) is located at the axial end of the sensor (100) and is used to acquire the measured pressure. The piezoelectric element (2) is capable of generating an electric charge signal based on the measured pressure collected; The transition element (3) is located axially between the diaphragm element (1) and the piezoelectric element (2); A clamping element (4) is located axially adjacent to the piezoelectric element (2), a transition element (3) is located axially on a first side of the piezoelectric element (2), and the clamping element (4) is located axially on a second side of the piezoelectric element (2), with the first side and the second side being disposed opposite to each other. as well as A pre-tightening sleeve (5) has a space defined by its radial inner wall to provide a first chamber (50), in which at least a portion of the transition element (3), the clamping element (4), and the piezoelectric element (2) are located; The radial inner wall of the pre-tightening sleeve (5) is in close contact with the radial outer wall of the transition element (3) and the clamping element (4), and the radial outer wall of the piezoelectric element (2) has a radial gap (G) with the radial inner wall of the pre-tightening sleeve (5).

2. The sensor (100) as described in claim 1, characterized in that, A heat insulation pad (30) is provided between the transition element (3) and the piezoelectric element (2).

3. The sensor (100) as described in claim 1, characterized in that, The piezoelectric element (2) comprises an X0-cut lanthanum gallium silicate crystal with a sheet-like structure.

4. The sensor (100) as described in claim 1, characterized in that, The diaphragm element (1) includes a diaphragm body (11) and an extension (12). The diaphragm body (11) provides an action surface for collecting the measured pressure. The extension (12) extends axially from the diaphragm body (11) and is fixedly connected to the transition element (3).

5. The sensor (100) as described in claim 4, characterized in that, The sensor (100) further includes a pre-tightening element (6), which is fixedly connected to the clamping element (4) on the second side of the clamping element (4); the sensor (100) further includes a first housing (7), the space defined by the radial inner wall of the first housing (7) provides a second chamber (70), the pre-tightening sleeve (5) is located in the second chamber (70), and the diaphragm body (11) and the pre-tightening element (6) are fixedly connected to the first housing (7) at the axial end of the first housing (7).

6. The sensor (100) as claimed in claim 5, characterized in that, The first housing (7) includes a first housing body (71) and a flange (72) extending radially outward from the first housing body (71). The sensor (100) also includes a second housing (8). The space defined by the radial inner wall of the second housing (8) provides a third chamber (80). The first housing body (71) is located in the third chamber (80). The flange (72) is fixedly connected to one axial end of the second housing (8), and a cover (9) is fixedly connected to the other axial end, such that the cover (9) and the diaphragm body (11) close the third chamber (80) at both axial ends.

7. The sensor (100) as claimed in claim 6, characterized in that, The outer wall of the second housing (8) has an external thread (81), and the second housing (8) is separated from the pre-tightening sleeve (5) by the first housing (7).

8. The sensor (100) as claimed in claim 1, characterized in that, The piezoelectric element (2) is connected to a first conductive element (21) and a second conductive element (22) arranged opposite to each other; the transition element (3) and the clamping element (4) have a first wire hole (31) and a second wire hole (41) that penetrate their axial thickness respectively; the first wire (211) passes through the first wire hole (31) and is connected to the first conductive element (21), and the second wire (221) passes through the second wire hole (41) and is connected to the second conductive element (22).

9. An internal combustion engine, characterized in that, Includes a sensor (100) as described in any one of claims 1-8 and a cylinder, wherein the sensor (100) is disposed in the cylinder for measuring the cylinder pressure.

10. A method for manufacturing a sensor, used in the sensor (100) as described in any one of claims 1-8, characterized in that, include: The transition element (3), piezoelectric element (2), and clamping element (4) are arranged in an axially stacked manner; Apply a preload to the transition element (3) and the clamping element (4) so ​​that the transition element (3) and the clamping element (4) press the piezoelectric element (2) on both sides of the axial direction; The pre-tightening sleeve (5) is fitted onto the radial periphery of the transition element (3), the piezoelectric element (2), and the clamping element (4). The pre-tightening sleeve (5) is fixedly connected to the clamping element (4) at one end in the axial direction and to the transition element (3) at the other end in the axial direction.

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