Design of high-sensitivity mass-block-free piezoelectric acceleration sensor

Abstract

The invention discloses a high-sensitivity mass-block-free piezoelectric acceleration sensor design which is suitable for weak vibration signal detection in the fields of industrial equipment monitoring, aerospace, consumer electronics and the like. Aiming at the problems of high cost, large size and limited bandwidth caused by mass block design and mechanical rigidity adjustment of a traditional piezoelectric acceleration sensor, a single lead zirconate titanate piezoelectric ceramic (PZT) sheet is adopted as a sensitive element, and collaborative improvement of sensitivity and bandwidth is realized through innovative structural design. The core structure of the sensor comprises an early warning bolt, a gasket, an upper insulating sheet, a lower insulating sheet, a piezoelectric sensitive element and a base. The early warning bolt exerts high pre-tightening force through a shell threaded hole, provides rigid contact downward pressure and ensures the rigidity of the whole structure. The gasket and the upper and lower insulating sheets form complete equal-surface contact, the contact area of the piezoelectric ceramic is maximized, and a traditional mass block is replaced; the insulation sheet is provided with a welding groove and a wiring groove, flatness deviation caused by welding spots is avoided, and charge transmission stability is guaranteed. According to the design, a mass block is omitted, the structure is simplified, the preparation cost is reduced, and meanwhile the size miniaturization of the sensor is achieved through the synergistic effect of high pre-tightening force and a low-rigidity structure. Tests show that the sensitivity of the sensor reaches 192.3 pC / g, the use frequency range covers 10-3000Hz (recommended 10-700Hz), and the sensor has the characteristics of high sensitivity and wide bandwidth, and is suitable for the high-end fields of ultra-precision measurement, extreme environment monitoring and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of sensors, and in particular to a compression-type acceleration sensor. Background Art

[0002] As a key component in the field of precision measurement, the sensitivity of piezoelectric accelerometers directly affects the ability to detect weak vibration signals. They play an irreplaceable role in scenarios such as industrial equipment health monitoring, aerospace attitude control, and motion sensing in consumer electronics. Traditional piezoelectric accelerometers are based on the principle of positive piezoelectric effect. Through the mechanical deformation of the mass block caused by the inertial force, the surface of the piezoelectric material (such as lead zirconate titanate piezoelectric ceramics (PZT) or polyvinylidene fluoride (PVDF)) produces a charge signal output proportional to the acceleration. Its theoretical sensitivity is determined by the material's piezoelectric constant d ij and the sensor mechanical system stiffness k, the expression is

[0003]

[0004] (where m is the mass of the mass block). Existing technologies mainly achieve sensitivity improvement by optimizing the composition of piezoelectric materials or improving the stiffness of mechanical structures, such as using high d 33 Modified piezoelectric ceramics, increasing the mass of the proof mass, or reducing the structural stiffness. However, this approach increases the cost and size of the sensor, and mechanical structural adjustments can easily lead to a decrease in the sensor's natural frequency, creating a technical contradiction between increased sensitivity and reduced measurement bandwidth. These technical bottlenecks severely limit the application and expansion of piezoelectric accelerometers in high-end fields such as ultra-precision measurement and extreme environment monitoring. There is an urgent need to simultaneously overcome the technical barriers of sensitivity, bandwidth, and environmental adaptability through systematic innovative designs.

[0005] The present invention designs a new type of piezoelectric acceleration sensor, which uses a single ceramic piece as a sensitive element and achieves a maximum contact area while increasing the bolt preload. The above new structure replaces the mass block and ultimately achieves high sensitivity and wide bandwidth output. Summary of the Invention

[0006] The present invention provides a design of a high-sensitivity piezoelectric acceleration sensor, aiming to prepare a high-sensitivity and wide-bandwidth output piezoelectric acceleration sensor under simple process conditions.

[0007] The sensor comprises an early warning bolt, a gasket, an upper insulating sheet, a sensitive element, a lower insulating sheet and a base.

[0008] Preferably, the warning bolt is located at the uppermost section and is fixed through a threaded hole of the housing, and the length of the threaded hole provides a high warning force to the lower device and a downward pressure for overall rigid contact.

[0009] Preferably, the gasket is located between the warning bolt and the upper insulating sheet to avoid uneven force on the piezoelectric sensitive element caused by contact between the small circular surface and the large circular surface of the warning bolt and the insulating sheet. Adding a gasket in the middle can transfer the bolt pre-tightening force to the gasket, and the contact between the gasket and the insulating sheet can provide a relatively uniform complete surface warning force.

[0010] Preferably, the upper insulating sheet is the same as the lower insulating sheet, leaving welding grooves and wiring grooves. The welding grooves are used to store the connecting solder joints between the electrode wires and the piezoelectric sensitive elements, avoiding large gaps between the insulating sheet and the piezoelectric sensitive elements, and changes in flatness caused by solder joint problems.

[0011] Preferably, the piezoelectric sensitive element is composed of a lead zirconate titanate piezoelectric ceramic (PZT) sheet, which is placed between the upper and lower insulating sheets.

[0012] The base is the key connecting component between the sensor and the object being measured, primarily providing mechanical support and environmental adaptability. It ensures synchronous vibration between the sensor and the object being measured through a rigid connection, while also securing core components such as the insulating sheet and piezoelectric element, reducing signal distortion.

[0013] From the above technical solutions, it can be seen that the high-sensitivity piezoelectric acceleration sensor design of the present invention has certain advantages, as shown in the following:

[0014] 1. Use ordinary lead zirconate titanate piezoelectric ceramic (PZT) sheets to reduce the high voltage coefficient (d 33 ) and reduces the production cost of piezoelectric sensitive elements.

[0015] 2. The design of the mass block is eliminated, and the preparation cost of the sensor is further reduced on the basis of simplifying the structure.

[0016] 3. All components from the gasket to the base are in complete equal-surface contact, which improves the natural frequency of the sensor and effectively utilizes the maximum contact area of ​​the piezoelectric sensitive element.

[0017] 4. The simple structural design reduces the size of the sensor, making it more suitable for use in some precise spaces.

[0018] In summary, the designed high-sensitivity piezoelectric accelerometer has significant advantages in both technology and economy, and is expected to promote the widespread application of piezoelectric accelerometers and promote scientific and technological innovation and industrial development. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0020] Attachment Figure 1 This is a schematic diagram of the structure of the piezoelectric accelerometer in Example 1.

[0021] Attachment Figure 2 This is the overall assembly diagram of the piezoelectric acceleration sensor in Example 1.

[0022] Attachment Figure 3 This is a diagram of the insulating sheet parts in Example 1.

[0023] Attachment Figure 4 This is the amplitude-frequency curve of the piezoelectric acceleration sensor in Example 1.

[0024] Attachment Figure 5 This is a diagram of the insulating sheet parts in Example 2.

[0025] Numbers in the figure: 1. Warning bolt; 2. Gasket; 3. Upper insulating sheet; 4. Piezoelectric sensitive element; 5. Lower insulating sheet; 6. Base. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] Example 1: The present invention proposes a high-sensitivity piezoelectric acceleration sensor, including a warning bolt, a gasket, an upper insulating sheet, a sensitive element, a lower insulating sheet, and a base. The overall structure is shown in the attached Figure 1 , Attachment Figure 2 , connect the gasket, upper insulating sheet, sensitive element (piezoelectric ceramic), lower insulating sheet and base in turn, use screws to connect the shell and base through the 4 screw holes at the bottom, or directly use laser welding to connect the base and shell, pass the warning bolt through the threaded hole of the shell, and twist the warning bolt to give the piezoelectric sensitive element sufficient warning force.

[0028] The insulating sheet is shown in the attached Figure 3The insulating sheet has a welding groove and a wire groove. The welding groove is used for storing the welding point between the electrode wire and the piezoelectric sensitive element, avoiding the existence of a large gap between the insulating sheet and the piezoelectric sensitive element, and the change of flatness caused by the welding point.

[0029] The sensitive element uses common PZT piezoelectric ceramic (d 33 about 240 pC / N, and its sensitivity will be higher if a piezoelectric coefficient higher than that is used. The electrode wire is welded and led out by using solder in the middle position between the positive and negative poles of the ceramic, and the welding point and the connecting wire are clamped into the grooves of the upper and lower insulating sheets to complete the connection.

[0030] The response amplitude is tested by using an excitation platform, and the result is shown in the attached table. Figure 4 The overall sensitivity is about 1923 mV / g or 192.3 pC / g, the frequency band used is 10-3000 Hz, and the recommended frequency band is 10-700 Hz.

[0031] Example Two: The difference between Example One and Example Two is the design of the wire groove on the insulating sheet. The wire groove directly isolates the electrode wire from the piezoelectric ceramic.

[0032] The above description of the disclosed embodiments enables those skilled in the art to carry out or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A design of a high-sensitivity piezoelectric acceleration sensor, characterized by Under simple process conditions, a piezoelectric accelerometer with high sensitivity and wide bandwidth output was prepared.

2. According to claim 1, the sensor includes a warning bolt, a gasket, an upper insulating sheet, a sensitive element, a lower insulating sheet, and a base.

3. The warning bolt according to claim 1 is located at the uppermost section and is fixed through the threaded hole of the housing. The length of the threaded hole provides a high warning force to the device below and provides downward pressure for overall rigid contact.

4. The gasket according to claim 1 is located between the warning bolt and the upper insulating sheet, and is used to avoid the contact between the small circular surface of the warning bolt and the large surface of the insulating sheet, which causes uneven force on the piezoelectric sensitive element. Adding a gasket in the middle can convert the bolt preload force to the gasket, and the contact between the gasket and the insulating sheet can provide a relatively uniform complete surface warning force.

5. The upper insulating sheet according to claim 1 is the same as the lower insulating sheet, and has welding grooves and wiring grooves. The welding grooves are used to store the connecting solder joints between the electrode wires and the piezoelectric sensitive elements, avoiding large gaps between the insulating sheet and the piezoelectric sensitive elements, and avoiding flatness changes caused by solder joint problems.

6. The piezoelectric sensitive element according to claim 1 is composed of a lead zirconate titanate piezoelectric ceramic (PZT) sheet placed between upper and lower insulating sheets.

7. The device described in claim 1 is a key connecting component between the sensor and the object being measured, primarily providing mechanical support and environmental adaptation. Its rigid connection ensures synchronized vibration between the sensor and the object being measured, while also securing core components such as the insulating sheet and piezoelectric element, reducing signal distortion.

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