Acceleration sensor based on PVDF piezoelectric film

Abstract

The invention discloses an acceleration sensor based on a PVDF (polyvinylidene fluoride) piezoelectric film, which relates to the technical field of acceleration sensors and comprises a shell, an insulating shock pad, the PVDF piezoelectric film, a cantilever beam, an insulating base, a charge amplifier and the like. And the PVDF film is attached to the cantilever beam on which the mass block is fixed in a sticking manner. When the mass block and the cantilever beam are subjected to acting force in the impact direction, the piezoelectric film is driven to deform, the deformation can generate charge signals, the charge amplifier amplifies and outputs the electric signals, and the function that acceleration or vibration signals are converted into the electric signals to be called by a PC end is achieved. The high-sensitivity detection effect of the PVDF piezoelectric film acceleration sensor is achieved, the production process of the piezoelectric film acceleration sensor is simplified, the PVDF piezoelectric film acceleration sensor has the advantages of being good in environmental adaptability, low in manufacturing cost, good in long-term stability and the like, and a new manufacturing scheme is provided for applying the PVDF piezoelectric film to the field of single-axis acceleration detection.

Description

Technical Field

[0001] The invention belongs to the field of sensor technology, and in particular relates to an acceleration sensor based on a PVDF piezoelectric film and an application method thereof. Background Art

[0002] Accelerometers are one of the key sensors widely used in modern engineering and science to measure the acceleration or vibration of an object. They play an important role in many applications, including but not limited to vehicle safety, aerospace, medical devices, structural health monitoring, and smartphones.

[0003] Traditional accelerometers are usually based on piezoelectric crystals or micro-electromechanical systems (MEMS) technology. Although these technologies are reliable, they also have some limitations. For example, piezoelectric crystal sensors are relatively fragile and are not suitable for scenarios with high-frequency vibrations or large acceleration changes. MEMS accelerometers are mostly three-axis structures, and are expensive and complex to manufacture.

[0004] Piezoelectric films are popular in the market because of their low cost, simple structure and wide applicability. Polyvinylidene fluoride (PVDF) has excellent piezoelectric properties and is a polymer material with excellent mechanical properties that can be used to manufacture piezoelectric sensors. PVDF piezoelectric films generate electric charges when force or vibration is applied, which provides potential for their use in acceleration sensors.

[0005] For some situations where only the acceleration in a single direction or the vibration frequency needs to be detected, the cost of the three-axis acceleration sensor is still high and the functions are redundant. At present, the patent technology for using PVDF piezoelectric film for acceleration sensor is still limited, and innovation in this field is still to be developed. Therefore, it is necessary to provide a novel, economical and high-performance acceleration sensor that utilizes the superior performance of PVDF piezoelectric film to meet the needs of different fields. Summary of the invention

[0006] The purpose of the present invention is to provide an acceleration sensor based on a PVDF piezoelectric film, and to provide a piezoelectric acceleration sensor with high sensitivity, good environmental adaptability and low production cost.

[0007] The technical solution adopted by the present invention is as follows:

[0008] An acceleration sensor based on PVDF piezoelectric film, comprising an upper electrode, a lower electrode and a piezoelectric film arranged between the upper electrode and the lower electrode, wherein the upper electrode, the lower electrode and the piezoelectric film constitute a sensitive element, characterized in that it also includes a cantilever beam, an insulating shock-absorbing pad, a fixing part and an insulating base, wherein a groove is provided on the insulating base, the sensitive element is arranged on the cantilever beam, the left end of the cantilever beam is located in the groove, the insulating shock-absorbing pad is located in the upper and lower layers of the left end of the cantilever beam, and the fixing part fixes the cantilever beam in the groove of the insulating base by bolt connection.

[0009] Preferably, it further comprises a charge amplifier and a shell, wherein the charge amplifier and the insulating base are located inside the shell.

[0010] Preferably, the cantilever beam is a rectangular metal sheet, and the length and width of the rectangle are equal to the length and width of the sensitive element.

[0011] As a further preference, an adhesive is provided on the cantilever beam, and the sensitive element is arranged on the cantilever beam through the adhesive.

[0012] As a further preference, the insulating shock-absorbing pad is made of elastic rubber to eliminate the assembly gap between the shell, the insulating base and the cantilever beam.

[0013] Preferably, the sensor is a unidirectional acceleration sensor, that is, the sensor is only sensitive to acceleration from the direction of the insulating base and has no response to acceleration from the direction of the shell.

[0014] Preferably, the cantilever beam converts the acceleration applied to the insulating base into pressure or tension acting on the piezoelectric film to generate a charge signal proportional to the magnitude of the acceleration.

[0015] Preferably, the charge amplifier is connected to the sensitive element via a lead, and the charge amplifier amplifies and outputs the charge generated by the sensitive element for the PC to call.

[0016] The above technical solution has the following advantages or beneficial effects:

[0017] In the present invention, by improving the structure and implementation form of the PVDF piezoelectric film acceleration sensor, it can be easily installed, reduce the structural complexity, and reduce the device cost. The multiple components inside the piezoelectric film acceleration sensor are all installed on an insulating base connected to the shell, which can ensure the stability and reliability of the installation; at the same time, the charge amplifier is placed in the shell, which can achieve the effect of sensor function integration, avoid interference from the environment outside the shell, and facilitate installation and use.

[0018] The fixing part installs the sensitive element and the cantilever beam in the groove of the insulating base through bolt connection, and adds the insulating shock-absorbing pad between the fixing part and the cantilever beam, and between the cantilever beam and the insulating base, thereby reducing the assembly gap between the cantilever beam, the fixing part and the insulating base, and improving the stiffness of the contact area, so that the piezoelectric film acceleration sensor applies sufficient load to the cantilever beam when vibrating, and can generate sufficient charge in both the compression and tension directions of the sensitive element. The sensitivity, linearity and other indicators of the piezoelectric film acceleration sensor are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the present invention;

[0020] Figure 2 for Figure 1 A top view of

[0021] Figure 3 It is the equivalent principle circuit diagram of the charge amplifier;

[0022] Figure 4 It is a working principle diagram of the present invention.

[0023] In the figure: 1. Shell, 2. Sensitive element, 3. Charge amplifier, 4. Fixing part, 5. Insulation shock-absorbing pad 1, 6. Cantilever beam, 7. Insulation shock-absorbing pad 2, 8. High-speed data acquisition card, 9. Computer, 10. Exciter. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below through specific implementation modes. It should be understood that the specific implementation modes described herein are only used to explain the present invention and are not used to limit the present invention.

[0025] See also Figure 1 and Figure 2 The present invention discloses an acceleration sensor based on PVDF piezoelectric film, which includes a housing 1, a sensitive element 2, a charge amplifier 3, a fixing part 4, an insulating shock-absorbing pad 1 5, a cantilever beam 6, and an insulating shock-absorbing pad 2 7. The fixing part 4, the insulating shock-absorbing pad 1 5, the cantilever beam 6, and the insulating shock-absorbing pad 2 7 are arranged in the groove of the insulating base from top to bottom. The fixing part 4 and the cantilever beam 6 are connected by bolts with a pre-tightening force applied therebetween, and are fixed on the insulating base.

[0026] The fixing part 4, the insulating base groove and the left end of the cantilever beam are provided with threaded holes, which can be fixedly connected by bolts.

[0027] The charge amplifier 3 is fixed to the housing 1 by bolt connection. The insulating base is fixed to the housing 1, and a rectangular groove is provided on the upper end surface of the insulating base for fixing the cantilever beam 6. A lead groove is provided on the left side of the cantilever beam 6 for leading out the signal line of the sensitive element 2.

[0028] The housing 1 is made of high-strength stainless steel.

[0029] The sensitive element 2 is a circular PVDF piezoelectric film with electrode lead wires, which is fixed on the cantilever beam 6 by an adhesive. During the bonding process, a certain pre-pressure needs to be applied by a special fixture.

[0030] When there is acceleration externally, that is, when the acceleration sensor based on the PVDF piezoelectric film of the present invention is working, the acceleration force acts on the cantilever beam, and the cantilever beam transmits the acceleration signal to the sensitive element, causing the deformation of the sensitive element. The deformation of the sensitive element causes the strain deformation of the piezoelectric film layer. Due to the piezoelectric effect of the piezoelectric film layer, charges are generated on the surface of the piezoelectric film layer, so that the upper electrode and the lower electrode sense the corresponding charges, and then the electrical signals are output to the charge amplifier device through the upper electrode and the lower electrode, so that the charge amplifier can detect the corresponding acceleration signal.

[0031] During the vibration test, the computer 9 controls the exciter 10 to generate vibration and acceleration signals through the vibration control program, applies excitation to the sensitive element 2, and the PVDF piezoelectric film outputs the charge generated on the surface to the charge amplifier through the upper and lower electrodes. The charge amplifier then transmits the amplified voltage signal to the computer 9. The computer further processes the voltage signal to provide the magnitude of acceleration and the magnitude of vibration frequency.

[0032] The above embodiments are only exemplary embodiments of the present application and are not intended to limit the present application. The protection scope of the present application is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present application within the essence and protection scope of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present application.

Claims

1. An acceleration sensor based on a PVDF piezoelectric film, comprising an upper electrode, a lower electrode and a piezoelectric film arranged between the upper electrode and the lower electrode, wherein the upper electrode, the lower electrode and the piezoelectric film constitute a sensitive element, characterized in that: It also includes a cantilever beam, an insulating shock-absorbing pad, a fixing part and an insulating base, wherein the insulating base is provided with a groove, the cantilever beam is provided with the sensitive element, the left end of the cantilever beam is located in the groove, the insulating shock-absorbing pad is located in the upper and lower layers of the left end of the cantilever beam, and the fixing part fixes the cantilever beam in the groove of the insulating base by bolt connection.

2. An acceleration sensor based on PVDF piezoelectric film, characterized in that: Also included is a charge amplifier and a housing, wherein the charge amplifier and the insulating base are located within the housing.

3. The PVDF piezoelectric film-based acceleration sensor according to claim 1, characterized in that The cantilever beam is a rectangular metal sheet, and the length and width of the rectangle are equal to the length and width of the sensitive element.

4. The PVDF piezoelectric film-based acceleration sensor according to claim 1, characterized in that The cantilever beam is provided with adhesive, and the sensitive element is arranged on the cantilever beam through the adhesive.

5. The PVDF piezoelectric film-based acceleration sensor according to claim 1, characterized in that The insulating shock-absorbing pad is made of elastic rubber and is used to eliminate the assembly gap between the shell, the insulating base and the cantilever beam.

6. The PVDF piezoelectric film-based acceleration sensor according to claim 1, characterized in that The sensor is a unidirectional acceleration sensor, that is, the sensor is only sensitive to the acceleration from the base direction, and has no response to the acceleration from the shell direction.

7. The PVDF piezoelectric film-based acceleration sensor according to claim 1, characterized in that The cantilever beam converts the acceleration applied to the insulating base into pressure or tension, which acts on the piezoelectric film to generate a charge signal proportional to the magnitude of the acceleration.

8. The PVDF piezoelectric film-based acceleration sensor according to claim 1, characterized in that The charge amplifier is connected to the sensitive element through a lead, and the charge amplifier amplifies and outputs the charge generated by the sensitive element for the PC to call.

9. The PVDF piezoelectric film-based acceleration sensor according to claim 1, characterized in that The sensor can respond to accelerations from 0.001 to 2000g.

10. The PVDF piezoelectric film-based acceleration sensor according to claim 1, characterized in that The sensor can respond to vibrations in the frequency range of 1 to 100 Hz.

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