Tire strain type piezoelectric energy collector

Abstract

The utility model discloses a tire strain type piezoelectric energy collector, which relates to the field of tire energy collection, adopts an approximate cymbal shape, and specifically comprises a contact piece connected to a fixed surface of the inner surface of a tire; the two supporting legs are symmetrically arranged on the two sides of the bottom of the contact piece, and the bottoms of the two supporting legs are connected with bonding layers bonded to the inner surface of the tire; a flexible metal substrate; the piezoelectric material layer is connected between the contact piece and the flexible metal substrate, the piezoelectric material layer is made of a soft lead zirconate titanate material, the bonding layer takes a cyanoacrylate material as a bonding agent, the width of the piezoelectric material layer is set to be 5mm, and the thickness of the piezoelectric material layer 5 is set to be 0.5 mm. The tire strain type piezoelectric energy collector has the advantages that the tire strain type piezoelectric energy collector is designed, the tire condition is detected in the tire advancing process, the structure is simple, and the service life is long.

Description

Technical Field

[0001] The utility model relates to the technical field of tire energy harvesting, in particular to a tire strain-based piezoelectric energy harvester. Background Art

[0002] The safety of tires is crucial for maintaining the safety of vehicles and passengers. To monitor the condition of vehicle tires and the tire-road condition, a tire detection system has emerged. The tire detection system uses sensors embedded therein to monitor the tire and road conditions and sends this data to an on-vehicle computer center for processing.

[0003] Sensors installed on the wheels and inside the tires detect the vehicle speed 0.15 - 0.2 seconds faster than sensors installed on the vehicle body. Therefore, it is important to install some safety monitoring sensors inside the tires rather than other positions of the vehicle. Tire energy harvesters can generally be divided into electromagnetic, electrostatic, and piezoelectric types. Compared with the piezoelectric system, the output voltage of the electromagnetic and electrostatic systems is lower. In addition, the electrostatic requires an external voltage source, and the integration of the electromagnetic with electronics and microsystems is relatively complex. At the same time, the piezoelectric energy harvester has a higher energy density than the electromagnetic and electrostatic energy harvesters and has the advantage of a simple structure. Therefore, for practical use considerations, it is necessary to design a simple, practical, and long-service-life energy harvester. Based on this, this application proposes a tire strain-based piezoelectric energy harvester. Summary of the Utility Model

[0004] The purpose of the utility model is to solve the drawbacks existing in the prior art and propose a tire strain-based piezoelectric energy harvester.

[0005] To achieve the above purpose, the utility model adopts the following technical solutions:

[0006] A tire strain-based piezoelectric energy harvester, which adopts an approximate cymbal shape and specifically includes:

[0007] A contact part, which is connected to a fixed surface on the inner surface of the tire;

[0008] Two legs, which are symmetrically arranged on both sides of the bottom of the contact part, and the bottoms of the two legs are both connected with an adhesive layer adhered to the inner surface of the tire;

[0009] A flexible metal substrate;

[0010] A piezoelectric material layer, which is connected between the contact part and the flexible metal substrate.

[0011] Preferably, the piezoelectric material layer is made of a soft lead zirconate titanate material.

[0012] Preferably, the bonding layer is made of cyanoacrylate material as an adhesive.

[0013] Preferably, the width of the piezoelectric material layer is set to 5 mm, and the thickness of the piezoelectric material layer 5 is set to 0.5 mm.

[0014] Preferably, there is a gap between each flexible metal substrate and the piezoelectric material layer. The gap is not less than 1 mm. The gap can convert part of the radial displacement into the longitudinal displacement in the energy harvester and amplify the generated displacement.

[0015] Preferably, the electrode caps at the top and bottom of the piezoelectric material layer are connected to an external load resistor to measure the electric power output of the circuit by simulation.

[0016] Preferably, the legs are made of metal material.

[0017] In the present utility model, compared with the prior art, the advantages are as follows:

[0018] In this application, the energy harvester is designed with two support legs, enabling the energy harvester to be used for tires. Through the gap between the metal layer and the piezoelectric material layer, part of the radial displacement can be converted into the longitudinal displacement in the energy harvester and the generated displacement can be amplified. Therefore, the piezoelectric material can benefit from both the radial displacement and the longitudinal displacement. The piezoelectric charge constant (perpendicular to the polarization direction) coefficients all contribute to the performance of the energy harvester. At the same time, through the design of the materials, the energy harvester has a long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a position diagram of a tire strain type piezoelectric energy harvester proposed by the present utility model on a tire.

[0020] Figure 2 is Figure 1 an enlarged schematic diagram of part A in.

[0021] In the figure: 100 tire, 1 contact part, 2 legs, 3 flexible metal substrate, 4 bonding layer, 5 piezoelectric material layer, 6 gap. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only part of the embodiments of the present utility model, rather than all of the embodiments.

[0023] Such as Figure 1-2As shown, a tire strain-based piezoelectric energy harvester, a tire energy harvester designed based on the cymbal in a drum set. Since it is applied in a tire, it is impossible to use the entire cymbal shape design. Because the external force and deflection come from the contact part, which is where the tire energy harvester is connected to the inner surface of the tire 100 as a fixed component. Therefore, some modifications are made here to embed a design similar to the cymbal shape on the inner surface of the tire 100. The design is embedded in the inner layer of the tire 100. When the tire 100 reaches the contact part, the tire strain causes the energy harvester to deflect. Due to the nature of the piezoelectric material layer 5, the deflection of the energy harvester is converted into electrical energy.

[0024] The design of the energy harvester includes a flexible metal substrate 3 and a piezoelectric material layer 5, as Figure 1 shown. Two legs 2 are designed to enable the energy harvester to be used for the tire 100. At the same time, there is a gap 6 between each flexible metal substrate 3 and the piezoelectric material layer 5. Using such a gap 6 in the design converts part of the radial displacement into longitudinal displacement in the energy harvester and amplifies the generated displacement. Therefore, the piezoelectric material layer 5 can benefit from both the radial displacement and the longitudinal displacement, which will make both the d33 (piezoelectric charge constant parallel to the polarization direction) and d31 (perpendicular to the polarization direction) coefficients contribute to the performance of the energy harvester. Electrode caps are connected to the top and bottom of the piezoelectric material layer 5 and connected to a load resistor to measure the electrical power output simulated as a circuit.

[0025] Among them, aluminum is selected as the metal substrate for the flexible metal substrate 3 because it is lightweight. To maintain tire balance, the energy harvester cannot be too large or too heavy. And the piezoelectric material layer 5 is made of lead zirconate titanate (PZT) material. The overall width of the energy harvester is set to 5 mm.

[0026] Table 1. Design materials and parameters of the energy harvester

[0027]

[0028] In the selection of the adhesive in the bonding layer 4, cyanoacrylate is used, which is an adhesive that effectively bonds metal and rubber. And the tensile bonding strength of cyanoacrylate is 12 - 3 MPa in the temperature range of 25 - 150 °C and 13 - 11 MPa in the relative humidity range of 40% - 100%. By comparing the stress applied on the contact patch and the bonding strength in cyanoacrylate, it is obvious that cyanoacrylate is a reliable choice to connect the energy harvester to the inner surface of the tire under various temperatures and humidities.

[0029] In terms of the selection of the piezoelectric material layer 5, among the PZT ceramics, the maximum strain that the soft PZT (PZT-5H) can withstand is 0.175%; while the strain level of ordinary PZT is relatively low, at 0.11%, and the strain level of hard PZT (PZT-8) is the lowest, at 0.105%. The maximum longitudinal strain on the inner surface of the tire is about 0.3%; therefore, the maximum strain of the bonding layer 4 is about 0.075% (25% of the tire strain). In this design, the soft PZT-5H is selected as the piezoelectric material layer 5 for tire strain energy harvesting because its strain level is within the strain range transmitted from the tire to the piezoelectric material through the bonding layer 4.

[0030] The yield strength is the point at which the response of elastic behavior to stress transforms into plastic response. The yield lines of PZT-5H and the metal body (non-alloy structural steel) are 689 MPa and 275 MPa respectively. Therefore, through calculation, the stress during tire contact is about 0.174 MPa - 0.176 MPa. The yield strengths of both materials are significantly higher than the applied stress. Therefore, the energy harvester is safe and will never reach the yield point.

[0031] As described above, it is only the preferred specific implementation manner of the present utility model, but the protection scope of the present utility model is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present utility model, according to the technical solution and the inventive concept of the present utility model, making equivalent replacements or changes should be covered within the protection scope of the present utility model.

Claims

1. A tire strain-based piezoelectric energy harvester, characterized in that: Uses a similar cymbal shape, and specifically includes: a contact portion connected to a fixed surface of the tire inner surface; The contact portion comprises: two legs (2), the two legs (2) being symmetrically arranged on both sides of the bottom of the contact portion, and the bottoms of the two legs (2) are both connected with an adhesive layer (4) bonded to the inner surface of the tire (100); A flexible metal substrate (3), wherein the flexible metal substrate (3) is connected to the piezoelectric material layer (5); A piezoelectric material layer (5) is connected between the contact portion and the flexible metal substrate (3).

2. The tire strain-based piezoelectric energy harvester according to claim 1, characterized in that: The piezoelectric material layer (5) is made of soft lead zirconate titanate material.

3. The tire strain-based piezoelectric energy harvester according to claim 1, characterized in that: The bonding layer (4) is made of cyanoacrylate material as an adhesive.

4. The tire strain-based piezoelectric energy harvester according to claim 1, characterized in that: The width of the piezoelectric material layer (5) is set to 5 mm, and the thickness of the piezoelectric material layer (5) is set to 0.5 mm.

5. The tire strain-based piezoelectric energy harvester according to claim 1, characterized in that: There is a gap (6) between each of the flexible metal substrates (3) and the piezoelectric material layer (5), and the gap (6) is not less than 1 mm. The gap (6) can convert part of the radial displacement into the longitudinal displacement in the energy harvester and amplify the generated displacement.

6. The tire strain-based piezoelectric energy harvester according to claim 1, characterized in that: The electrode caps on the top and bottom of the piezoelectric material layer (5) are connected to external load resistors to measure the electrical power output of the circuit.

7. The tire strain-based piezoelectric energy harvester according to claim 1 is characterized by: The supporting legs (2) are made of metal material.

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