Tire sensor module and tire sensor device

Abstract

In order to provide a composite piezoelectric element capable of measuring deformation occurring in a specific direction with high sensitivity and high accuracy, and a tire condition measuring device equipped with the composite piezoelectric element, the composite piezoelectric element (10) includes: a first electrode layer (12); a piezoelectric body layer (13) disposed on the first electrode layer (12); and a second electrode layer (14) disposed on the piezoelectric body layer (13). When viewed from above, the composite piezoelectric element (10) includes: a measuring section (15) provided with the first electrode layer (12), the piezoelectric body layer (13) and the second electrode layer (14); and a buffer section (16) without the piezoelectric body layer (13).

Description

[0001] This application is a divisional application of Chinese Patent Application No. 201980078032.4, filed by the applicant on December 17, 2019, entitled "Composite piezoelectric element, tire condition measuring device, tire sensor module, tire sensor device and piezoelectric sensor". Technical Field

[0002] This invention relates to composite piezoelectric elements used in various sensors, tire condition measuring devices using composite piezoelectric elements, tire sensor modules having sheet-like piezoelectric sensors for detecting tire deformation, tire sensor devices having the tire sensor modules, and piezoelectric sensors. Background Technology

[0003] Piezoelectric elements have the function of converting electrical energy into mechanical energy and are used as various actuators and sensors. For example, in order to determine the condition of a tire using the electrical energy generated by deformation, a flexible, thin-film piezoelectric element is sometimes used. Patent Document 1 describes a method in which a piezoelectric thin film is disposed inside the tire to estimate the tire's attitude angle and road surface condition. Furthermore, this document describes a road surface condition estimation device in which a piezoelectric sensor is disposed on the inner side of the tire tread as a means of estimating the tire's setting state by detecting tire deformation.

[0004] As a tire sensor device for detecting road surface conditions and tire conditions, a device consisting of a container disposed on the inner side of the tire tread and a tire sensor module that can be mounted in the container has been proposed. The tire sensor device uses an acceleration sensor disposed in the tire sensor module to detect vibrations transmitted to the tire, and detects the road surface condition by analyzing the vibration waveform. For example, Patent Document 2 describes a sensor (tire sensor module) mounted with a protrusion in the molding resin portion that seals the acceleration sensor, circuit board, and antenna, making it easier to identify the acceleration detection direction. However, a tire sensor module with a sheet-type piezoelectric sensor (piezoelectric element) assembled in a portion of it has not been proposed.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2014-234038

[0008] Patent Document 2: Japanese Patent Application Publication No. 2017-114438 Summary of the Invention

[0009] The technical problem that the invention aims to solve

[0010] In the method described in Patent Document 1, multiple piezoelectric films of varying lengths are arranged inside a tire by reorienting them to measure deformation in different directions. However, since the piezoelectric elements constituting the piezoelectric films are formed as a single unit, the piezoelectric elements deform as a whole when the object being measured deforms. Therefore, when measuring deformation in a specific direction, the piezoelectric films are affected by deformation in directions other than that specific direction. Consequently, it is difficult to measure deformation occurring in a specific direction with high sensitivity and high accuracy.

[0011] Furthermore, if a sheet-like piezoelectric sensor, such as an accelerometer in a tire sensor module, is sealed with a molding resin portion, the deformation of the piezoelectric sensor is hindered by the relatively rigid molding resin portion, thus reducing the sensor's sensitivity to tire deformation. In other words, when a sheet-like piezoelectric sensor is assembled as part of a tire sensor module, if it is sealed with a molding resin portion in the same way as an accelerometer, there is a problem of reduced detection sensitivity of the piezoelectric sensor.

[0012] Therefore, the object of the present invention is to provide a composite piezoelectric element capable of measuring deformation occurring in a specific direction with high sensitivity and high accuracy, a tire condition measuring device having the composite piezoelectric element, a tire sensor module having a piezoelectric film with good detection sensitivity for tire deformation, a tire sensor device having the tire sensor module, and a piezoelectric sensor.

[0013] Means for solving technical problems

[0014] The composite piezoelectric element of the present invention includes: a first electrode layer; a piezoelectric body layer disposed on the first electrode layer; and a second electrode layer disposed on the piezoelectric body layer. When viewed from above, the composite piezoelectric element includes: a measuring section having the first electrode layer, the piezoelectric body layer, and the second electrode layer; and a buffer section without the piezoelectric body layer. By providing a buffer section without the piezoelectric body layer, anisotropic measurement sensitivity of the measuring section can be imparted, enabling high sensitivity and high accuracy in measuring deformation occurring in a specific direction.

[0015] Preferably, the piezoelectric layer has multiple strip-shaped portions when viewed from above. The aspect ratio of the strip-shaped portions can be set to, for example, 1000:1 to 10:5. Preferably, the multiple strip-shaped portions are arranged in a manner that is substantially parallel along their long sides. Preferably, the buffer portion is formed between adjacent strip-shaped portions along the long side direction of the strip-shaped portion. Furthermore, preferably, the buffer portion has a cutout portion provided along the long side direction of the measuring portion when viewed from above. Preferably, the cutout portion is a continuous slit along the long side direction of the strip-shaped portion when viewed from above. These structures can increase the anisotropy of the measuring sensitivity of the composite piezoelectric element.

[0016] Alternatively, the composite piezoelectric element of the present invention may include a base film, on which the first electrode layer is disposed. By using the base film, the composite piezoelectric element can be easily disposed on a measurement object such as a tire while maintaining its shape. In this case, it is preferable that the base film, when viewed from above, is formed on both the measuring portion and the buffer portion, whereby the Young's modulus of the buffer portion is smaller than that of the measuring portion. This structure increases the anisotropy of the measurement sensitivity of the composite piezoelectric element.

[0017] The tire condition measuring device of the present invention includes the composite piezoelectric element of the present invention.

[0018] The tire sensor module of the present invention is characterized by comprising: a sheet-shaped piezoelectric sensor capable of measuring tire deformation; and a control unit capable of processing the measurement results of the piezoelectric sensor, wherein a buffer unit is provided between the piezoelectric sensor and the control unit.

[0019] By providing a buffer between the piezoelectric sensor and the control unit, it is possible to suppress the deformation of the sheet-like piezoelectric sensor following the tire from being hindered by the control unit. In other words, the sheet-like piezoelectric sensor can be assembled into the tire sensor module in a state that is easily flexible in accordance with the deformation of the tire.

[0020] Alternatively, the buffer section may include a flexible portion with a Young's modulus smaller than that of the control section, and this flexible portion contacts both the piezoelectric sensor and the control section. The Young's modulus of the flexible section can be between 10 MPa and 1000 MPa.

[0021] The flexible part that absorbs the deformation of the piezoelectric sensor comes into contact with both the piezoelectric sensor and the control unit, thereby maintaining their positional relationship. As a result, the measurement conditions become constant, and the measurement accuracy of the piezoelectric sensor is improved.

[0022] Alternatively, the buffer portion may include the soft portion and the gap portion, and the soft portion may also include a slit.

[0023] By providing a gap in the buffer section without a flexible part, or by providing a slit in the flexible part, the flexible part can be easily deformed in the buffer section, thus making the piezoelectric sensor more prone to deformation.

[0024] Alternatively, the flexible part may have a slit, and the control part may have an anchor that is inserted into the slit.

[0025] By incorporating a slit, the flexible part becomes easily deformable, and the positional relationship between the flexible part and the control part can be stably maintained by the fixing element. As a result, the measurement conditions become constant, and the measurement accuracy of the piezoelectric sensor is improved.

[0026] Alternatively, the control unit may include a communication unit. Alternatively, the control unit may include a magnetic sensor, an accelerometer, or a magnet.

[0027] The tire sensor device of the present invention is characterized by comprising: the above-described tire sensor module; and a container capable of elastic deformation, capable of containing the tire sensor module and being fixed to the inside of the tire.

[0028] Alternatively, the container may have a container-side fixing member for holding the piezoelectric sensor of the tire sensor module in a predetermined position.

[0029] The tire sensor module described above can also be configured such that the buffer portion has a soft portion with a Young's modulus smaller than that of the control portion, and the soft portion contacts the piezoelectric sensor and the control portion.

[0030] The piezoelectric sensor of the present invention is characterized in that it is a sheet-shaped piezoelectric sensor and is circular when viewed from above in the direction of the normal of the sheet, and the piezoelectric sensor detects the deformation of the tire.

[0031] By setting it to a circle, measurements can be taken under the same conditions regardless of the orientation of the piezoelectric sensor, making it easier to install the piezoelectric sensor on the tire.

[0032] Invention Effects

[0033] The composite piezoelectric element of the present invention can buffer the effect of deformation of the measurement object occurring outside a specific direction on the piezoelectric layer through a buffer portion. Therefore, deformation in a specific direction can be measured with high sensitivity and high accuracy.

[0034] The tire sensor module of the present invention, by providing a buffer portion between the sheet-like piezoelectric sensor and the control unit, allows the sheet-like piezoelectric sensor to easily deform in response to tire deformation, thus enabling high-sensitivity detection of tire deformation. Therefore, a tire sensor module and tire sensor device with excellent detection sensitivity can be provided. Attached Figure Description

[0035] Figure 1 (a) is a top view schematically showing the structure of the composite piezoelectric element in the first embodiment, and (b) is... Figure 1 (a) is a sectional view along line AA, and (c) is... Figure 1 (a) BB-direction sectional view.

[0036] Figure 2 (a) is a top view schematically showing the structure of a composite piezoelectric element of a modified example of the first embodiment, and (b) is... Figure 2 (a) is a sectional view along line AA, and (c) is... Figure 2 (a) BB-direction sectional view.

[0037] Figure 3 (a) is a top view schematically showing the structure of the composite piezoelectric element according to the second embodiment, and (b) is... Figure 3 (a) is a sectional view along line AA, and (c) is... Figure 3 (a) BB-direction sectional view.

[0038] Figure 4 (a) is a top view schematically showing the structure of a composite piezoelectric element according to a modified example of the second embodiment, and (b) is... Figure 4 (a) is a sectional view along line AA, and (c) is... Figure 4 (a) BB-direction sectional view.

[0039] Figure 5 The diagram schematically illustrates the tire condition measurement performed by the tire condition measuring device of the third embodiment, showing (a) a top view of the tire not rotating while parked, and (b) a top view of the tire rotating while in motion.

[0040] Figure 6 (a) is a cross-sectional view showing the tire sensor module and tire sensor device according to the fourth embodiment, and (b) is... Figure 6 (a) BB-direction sectional view.

[0041] Figure 7 This is a cross-sectional view showing a modified example of the tire sensor module and tire sensor device according to the fourth embodiment.

[0042] Figure 8 This is a cross-sectional view showing the tire sensor module and tire sensor device according to the fifth embodiment.

[0043] Figure 9 This is a cross-sectional view showing a modified example of the tire sensor module and tire sensor device according to the fifth embodiment.

[0044] Figure 10 (a) is a cross-sectional view showing a modified example of the tire sensor module and tire sensor device according to the fifth embodiment, and (b) is... Figure 10 (a) BB-direction sectional view.

[0045] Figure 11 (a) is a cross-sectional view showing a modified example of the tire sensor module and tire sensor device according to the fifth embodiment, and (b) is... Figure 11 (a) BB-direction sectional view.

[0046] Figure 12 This is a cross-sectional view showing a modified example of the tire sensor module and tire sensor device according to the fifth embodiment.

[0047] Figure 13 Here are (a) top views and (b) views of a piezoelectric sensor. Figure 13 (a) CC-direction sectional view.

[0048] Figure 14 It is a three-dimensional diagram showing the tire sensor module separated from the container, which constitutes the tire sensor device.

[0049] Figure 15 This is a partial cross-sectional perspective view showing the state of the tire sensor device installed on the tire. Detailed Implementation

[0050] Hereinafter, embodiments of the present invention will be described with reference to the figures. In each figure, the same parts are labeled with the same numbers, and descriptions are omitted where appropriate.

[0051] (First Implementation)

[0052] Figure 1 (a) is a top view schematically showing the structure of the composite piezoelectric element 10 according to this embodiment. Figure 1 (b) is Figure 1 (a) AA-direction sectional view, Figure 1 (c) is Figure 1 (a) is a BB-direction cross-sectional view. As shown in these figures, the composite piezoelectric element 10 includes a base film 11, a first electrode layer 12 disposed on the base film 11, a piezoelectric body layer 13 disposed on the first electrode layer, and a second electrode layer 14 disposed on the piezoelectric body layer 13.

[0053] First, the configuration and shape of each component of the composite piezoelectric element 10 when viewed from above will be described. For example... Figure 1 (a)~ Figure 1As shown in (c), the composite piezoelectric element 10 includes: a measuring section 15, which is formed by sequentially stacking a first electrode layer 12, a piezoelectric layer 13, and a second electrode layer 14 in the Z direction; and a buffer section 16 where the piezoelectric layer 13 is not provided. Instead of making the measuring section 15 the entire composite piezoelectric element 10, the buffer section 16 is provided in a portion of it, so that the force applied to the piezoelectric layer 13 of the measuring section 15 varies according to the direction of deformation of the measured object, thereby giving the measuring sensitivity of the composite piezoelectric element 10 anisotropy.

[0054] The measuring sections 15 are continuously arranged in the X direction, so when the object being measured deforms in the X direction, the deformation is directly transmitted to the piezoelectric layer 13 of the measuring section 15. In contrast, the measuring sections 15 and buffer sections 16 are alternately arranged in the Y direction. That is, buffer sections 16 are provided between the measuring sections 15, so when the object being measured deforms in the Y direction, the buffer sections 16 between the measuring sections 15 deform first, and the deformation is buffered and transmitted to the piezoelectric layer 13 of the measuring section 15. Therefore, the sensitivity for measuring deformation in the X direction can be improved, and the sensitivity for measuring deformation in the Y direction can be reduced. Therefore, by providing buffer sections 16 to the composite piezoelectric element 10, the sensitivity can be varied according to the direction in the XY plane, enabling high-sensitivity and high-precision measurement of deformation of the object being measured in a specific direction.

[0055] The measuring section 15 of the composite piezoelectric element 10 is configured such that, when viewed from above, a piezoelectric layer 13 having multiple strip-shaped portions 13a, 13b, 13c (hereinafter appropriately referred to as strip-shaped portions 13a to c) formed in a generally rectangular shape is sandwiched between a first electrode layer 12 and a second electrode layer 14 formed in a comb-like shape. Figure 1 As shown in (a), the multiple strip-shaped portions 13a to 13c are arranged in a manner in which their long sides are approximately parallel. In addition, the strip-shaped portions 13a to 13c can be anisotropic shapes as long as they have different widths in orthogonal directions.

[0056] The piezoelectric layer 13 is not a single piece when viewed from above, but is divided into three strip-shaped portions 13a to 13c arranged at predetermined intervals along the short side (Y direction). With this structure, the composite piezoelectric element 10 can improve the measurement sensitivity in the long side (X direction) and buffer the effect of deformation in the short side (Y direction) on the long side (X direction), enabling high-sensitivity and high-precision measurement of deformation in the long side (X direction). Furthermore, as long as the buffer portion 16 can buffer the effect of deformation in the short side (Y direction), the piezoelectric layer 13 can also have a shape with a partially continuous portion.

[0057] Buffer portions 16 are formed between adjacent strip portions 13a and 13b, and between adjacent strip portions 13b and 13c, respectively, along the long side direction of the strip portions 13a to 13c, and cut portions 17 are formed in each buffer portion 16.

[0058] The cut-out portion 17 can be formed, for example, by removing the base film 11 between the strip portions 13a-c using a laser after forming the composite piezoelectric element 10. The cut-out portion 17 is a portion where none of the base film 11, the first electrode layer 12, the piezoelectric layer 13, or the second electrode layer 14 is formed. Therefore, if the object being measured, such as a tire, deforms in the short-side direction of the strip portions 13a-c, the cut-out portion 17 deforms before the strip portions 13a-c. Because the cut-out portion 17 deforms first, it can buffer the impact on the piezoelectric layer 13 and suppress deformation of the piezoelectric layer 13. Therefore, the sensitivity of the composite piezoelectric element 10 in measuring deformation in the short-side direction of the strip portions 13a-c is reduced.

[0059] Each cut 17 is configured as a continuous slit along the long side (X direction) of the strips 13a to 13c when viewed from above. By configuring the cuts 17 as continuous slits, the influence on the piezoelectric layer 13 can be effectively buffered when the test object deforms in the short side direction of the strips 13a to 13c. That is, when the deformation of the test object occurs in the short side direction of the strips 13a to 13c, it is absorbed by the slit-shaped cut 17 and transmitted to the piezoelectric layer 13. In contrast, when the test object deforms in the long side direction of the strips 13a to 13c, the cut 17 does not buffer the influence on the piezoelectric layer 13. That is, when the deformation of the test object occurs in the long side direction of the strips 13a to 13c, it is not absorbed by the slit-shaped cut 17 and transmitted to the piezoelectric layer 13. Therefore, the composite piezoelectric element 10 can buffer the influence of deformation in the short side direction during the measurement of deformation in the long side direction of the strip 13a to c, and can measure the deformation in the long side direction with high sensitivity and high accuracy.

[0060] As described above, by providing a buffer portion 16 with a slit 17 between the strip portions 13a to c, the measurement sensitivity can vary significantly depending on whether the deformation of the measured object is in the short or long side direction of the strip portions 13a to c. Therefore, the composite piezoelectric element 10 can measure the force applied in a specific direction with high sensitivity and high accuracy. In other words, by making the detection sensitivity for forces applied in directions other than the specific direction (e.g., directions orthogonal to the specific direction) less sensitive, noise (components other than the specific direction) is difficult to pick up.

[0061] The base film 11 is provided with a first electrode layer 12, which is formed of a flexible synthetic resin film. Examples of synthetic resins include polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), polyethylene (PE), and aramid resin. The aforementioned synthetic resin may contain additives such as curing agents and inorganic fillers, and may also be an insulating film with insulating properties. The thickness of the base film 11 is, for example, set to approximately 25 μm to 125 μm.

[0062] First electrode layer 12 Figure 1 (a)~ Figure 1 As shown in (c), a layer of conductive powder dispersed in a synthetic resin matrix is ​​laminated on one side of the base film 11. Examples of synthetic resins include phenolic resin, polyurethane resin, epoxy resin, polyester resin, and acrylic resin. Examples of conductive powders include metal powders such as silver, copper, and nickel, as well as carbon powders such as graphite and nano-carbon. The conductive powder is dispersed in the synthetic resin at a concentration of approximately 5 to 70% (volume). The thickness of the first electrode layer 12 is, for example, approximately 5 μm to 15 μm.

[0063] Second electrode layer 14 Figure 1 (a)~ Figure 1 As shown in (c), the piezoelectric layer 13 is formed on one side of the base film 11 by stacking a piezoelectric layer 13 between the first electrode layer 12 and the second electrode layer 14. Furthermore, the second electrode layer 14, like the first electrode layer 12, is a layer in which conductive powder is dispersed in a synthetic resin matrix, and its thickness is, for example, about 5 μm to 20 μm.

[0064] The first electrode layer 12 and the second electrode layer 14 can be formed, for example, by adding a curing agent to a synthetic resin such as phenolic resin, mixing a solvent such as methanol acetate with a conductive powder to form a conductive paste, and forming it using methods such as screen printing. The first electrode layer 12 can be formed by coating the conductive paste onto a base film 11, heating it, and then drying and curing it. Similarly, the second electrode layer 14 can be formed by coating the conductive paste onto a piezoelectric layer 13, heating it, and then drying and curing it.

[0065] The first electrode layer 12 and the second electrode layer 14 are respectively provided with terminal portion 121 and terminal portion 141. These terminal portions 121 and terminal portions 141 are formed in such a way that they are led out all the way to the end of the base film 11, so that voltage supply and measurement results can be easily obtained.

[0066] piezoelectric layer 13 Figure 1 (a)~ Figure 1 As shown in (c), it is disposed on one side of the base film 11 and stacked on the first electrode layer 12 to form the electrode. Figure 1 In (a), the positions of the piezoelectric layer 13 (strip portions 13a, 13b, 13c, and measuring portion 15) are shown using thick dashed lines to indicate the position when viewed from above. Furthermore, in the portion between the first electrode layer 12 and the second electrode layer 14 where the piezoelectric layer 13 is not present, an insulating layer or similar material may be formed to prevent conductivity between the first electrode layer 12 and the second electrode layer 14.

[0067] From the viewpoint of ensuring good sensitivity in the long side direction, the aspect ratio (length L: width W1) of the strip portions 13a to c is preferably 1000:1 or more and 10:5 or less, more preferably 100:1 or more and 10:4 or less, and even more preferably 10:1 or more and 10:3 or less.

[0068] When viewed from above, the aspect ratio (length L: width W2) of the contour shape (hereinafter appropriately referred to as "shape of piezoelectric layer 13") of the piezoelectric layer 13 and the buffer portion 16 as an integral part is preferably 10:1 or more and 10:10 or less, more preferably 10:3 or more and 10:8 or less, and even more preferably 10:4 or more and 10:6 or less.

[0069] When the composite piezoelectric element 10 is mounted on a tire, the length L of the piezoelectric layer 13 in the long side direction is preferably about 10 mm to 20 mm. Therefore, preferred shapes of the piezoelectric layer 13 (length L × width W2) include, for example, 15 mm × 7 mm and 10 mm × 5 mm.

[0070] In this embodiment, a piezoelectric layer 13 having three strip portions 13a to c and two buffer portions 16 has been described, but the number of strip portions 13a to c and buffer portions 16 is not limited thereto. However, from the viewpoint of manufacturing efficiency, it is preferable to set the width W1 of the strip portions 13a to c to 1 mm or more. Therefore, typically, the number of strip portions 13a to c is about 2 to 4, and the number of buffer portions 16 is about 1 to 3.

[0071] The piezoelectric layer 13 is a layer in which piezoelectric particles are dispersed in a synthetic resin matrix. From the viewpoint of forming a composite piezoelectric element 10 that improves the piezoelectric properties of the piezoelectric layer 13 and has excellent output performance, the piezoelectric particles are preferably perovskite-structured strong dielectric particles. Potassium niobate (KNbO3), potassium sodium niobate, and barium titanate are preferably used as strong dielectric particles.

[0072] Potassium niobate is preferably potassium niobate with an average particle size (median particle size, D50) of 400 nm to 500 nm, an orthorhombic-to-tetragonal transition temperature of 223°C or higher and 228°C or lower, and a tetragonal-to-cubic transition temperature of 420°C or higher and 430°C or lower. This allows for the provision of a composite piezoelectric element 10 with further improved piezoelectric properties of the piezoelectric layer 13 and superior output performance.

[0073] The piezoelectric layer 13 is a composite material of synthetic resin and piezoelectric particles, and is flexible. From the viewpoint of suppressing the generation of cracks and the like caused by deformation of the piezoelectric layer 13, a synthetic resin with moderate flexibility at room temperature is preferred. As such a synthetic resin, an amorphous polyester resin or a polyurethane resin is preferred. In addition, amorphous polyester resins and polyurethane resins are generally widely used and are preferred in that they are readily available and inexpensive.

[0074] exist Figure 1 (b) and Figure 1 In (c), an example of a piezoelectric layer 13 consisting of a single layer is shown, but it can also be consisting of multiple layers. For example, the piezoelectric layer 13 can also be consisting of two first piezoelectric layers and a second piezoelectric layer disposed between the two first piezoelectric layers. In this case, it is preferable that the volume percentage concentration of piezoelectric particles in the two first piezoelectric layers is higher than that in the second piezoelectric layer therebetween. For example, when potassium niobate is used as the piezoelectric particles, the volume percentage concentration of piezoelectric particles in the first piezoelectric layer is preferably 50 vol% to 65 vol%. The volume percentage concentration of piezoelectric particles in the second piezoelectric layer is preferably 0.01 vol% to 60 vol%, more preferably 10 vol% to 50 vol%.

[0075] By reducing the volume percentage concentration of piezoelectric particles in the second piezoelectric layer, the bending resistance is improved. This improved bending resistance of the second piezoelectric layer results in increased bending resistance of the piezoelectric layer 13 as a whole compared to a single layer composed of a piezoelectric material with a high volume percentage concentration of piezoelectric particles. Furthermore, by employing a structure consisting of a first piezoelectric layer with a high volume percentage concentration of piezoelectric particles sandwiching a second piezoelectric layer, the piezoelectric performance of the piezoelectric layer 13 as a whole is not significantly reduced, prioritizing the performance of the first piezoelectric layer. Thus, a composite piezoelectric element 10 that maintains piezoelectric performance and improves bending resistance can be provided. Additionally, by sandwiching a second piezoelectric layer with a low volume percentage concentration of piezoelectric particles, a piezoelectric layer 13 can be constructed that reduces the amount of expensive piezoelectric particles used while maintaining piezoelectric performance.

[0076] The piezoelectric layer 13 can be manufactured, for example, in the following manner.

[0077] First, using a solvent-soluble amorphous polyester resin or polyurethane resin, the adhesive resin, solvents such as methanol acetate, and potassium niobate particles are mixed in the desired proportion, and then the mixture is evenly dispersed using a mixer such as a three-roller mixer to prepare a dielectric paste.

[0078] Next, using methods such as screen printing, a dielectric paste is applied in an overlapping manner when viewed from above to cover the first electrode layer 12 on one side of the base film 11, and then dried and hardened to form a piezoelectric layer 13. Figure 1 In (a), as shown by the dashed line, an example is shown where strip-shaped portions 13a to 13c are formed in the portion of the first electrode layer 12 that is formed in a comb-like shape when viewed from above. However, the piezoelectric layer 13 may also be formed in such a way that the portion connecting the three teeth is integrally overlapped with the first electrode layer 12. The thickness of the cured piezoelectric layer 13 is preferably 5 μm to 100 μm, more preferably 15 μm to 50 μm.

[0079] Furthermore, in the aforementioned dielectric paste, a small amount of curing agent or defoamer can be used appropriately. Additionally, the surface of the potassium niobate particles can be treated to bear a silane coupling agent. In particular, by adding a defoamer and treating with a silane coupling agent, defects such as bubbles in the piezoelectric layer 13 can be prevented, and poor conductivity in the thickness direction of the piezoelectric layer 13 can be reduced.

[0080] Finally, the formed piezoelectric layer 13 is subjected to polarization treatment. The polarization treatment involves heating the formed piezoelectric layer 13 to a temperature near the Curie point, and then... Figure 1In diagram (a), a DC voltage of approximately 1 to 10 V / μm, corresponding to the thickness of the piezoelectric layer 13, is applied to the terminal portions 121 of the first electrode layer 12 and 141 of the second electrode layer 14. Then, after returning to room temperature, the first electrode layer 12 and the second electrode layer 14 are short-circuited to remove excess capacitance, and the process ends. Preferably, the applied DC voltage is 4 to 6 V / μm. This allows the piezoelectric layer 13 to be easily processed from its initial state to a polarized state.

[0081] As described above, since the first electrode layer 12, the piezoelectric layer 13 and the second electrode layer 14 disposed on the surface of the base film 11 are formed by dispersing fillers in synthetic resin, the composite piezoelectric element 10 as a whole is flexible.

[0082] in addition, Figure 1 The composite piezoelectric element 10 does not have an overcoat component, but an overcoat component that protects against the external environment can be provided. The overcoat component can be, for example, an insulating paste based on a pigment-containing insulating polyurethane resin. The paste is applied and layered using methods such as screen printing to cover the entire second electrode layer 14, and then heated to dry and cure. The thickness of the cured overcoat component is approximately 10 μm to 100 μm. In addition to polyurethane resin, acrylic resin, polyester resin, epoxy resin, etc., can also be used.

[0083] As described above, the composite piezoelectric element 10 is formed using a simple and inexpensive screen printing method, thus enabling it to be manufactured easily and cheaply.

[0084] Figure 2 (a) is a top view schematically showing the structure of a modified example of this embodiment, namely the composite piezoelectric element 20. Figure 2 (b) is Figure 2 (a) AA-direction sectional view, Figure 2 (c) is Figure 2 (a) is a BB-direction sectional view. Figure 2 As shown in (a), the buffer portion 16 of the composite piezoelectric element 20 has multiple cutouts 17 along the long side direction of the strip portions 13a to c. Thus, by discontinuously providing multiple cutouts 17 in the buffer portion 16, anisotropy can be imparted to the measurement sensitivity of the measuring portion 15. Therefore, like the composite piezoelectric element 10, the composite piezoelectric element 20 can measure the deformation along the long side direction of the strip portions 13a to c with high sensitivity and high accuracy.

[0085] (Second Implementation)

[0086] Figure 3(a) is a top view schematically showing the structure of the composite piezoelectric element 30 according to this embodiment. Figure 3 (b) is Figure 3 (a) AA-direction sectional view, Figure 3 (c) is Figure 3 (a) is a BB-direction cross-sectional view. As shown in these figures, when viewed from above, the composite piezoelectric element 30 of this embodiment differs from the composite piezoelectric element 10 of the first embodiment in that the composite piezoelectric element 30, including the buffer portion 16, has a base film 11 integrally formed.

[0087] In the composite piezoelectric element 10 of the first embodiment described above, a notch 17 is provided in the buffer portion 16 to increase the difference in measurement sensitivity between the short and long sides of the strip portions 13a-c. In contrast, in the composite piezoelectric element 30 of this embodiment, although the notch 17 is not provided in the buffer portion 16, the buffer portion 16 has a relatively smaller Young's modulus compared to the measuring portion 15, and is prone to deformation in the short side direction of the strip portions 13a-c. Therefore, when the object being measured deforms in the short side direction, the buffer portion 16 deforms before the measuring portion 15, thereby buffering the force applied to the measuring portion 15 in the short side direction. Therefore, the composite piezoelectric element 30 can measure the deformation in the long side direction of the strip portions 13a-c with high sensitivity and high accuracy.

[0088] From the viewpoint of measuring deformation occurring in a specific direction with high sensitivity and high accuracy, the Young's modulus of the buffer portion 16 is preferably less than the Young's modulus of the measuring portion 15, more preferably less than half of the Young's modulus of the measuring portion 15, and even more preferably less than one-tenth of the Young's modulus of the measuring portion 15. The Young's modulus of the measuring portion 15 and the buffer portion 16 refer to... Figure 3 The Young's modulus in the XY plane in (a). In addition, the Young's modulus of the measuring section 15 is the Young's modulus of the laminate composed of the base film 11, the first electrode layer 12, the piezoelectric layer 13 and the second electrode layer 14, and the Young's modulus of the buffer section 16 is the Young's modulus of the base film 11.

[0089] Figure 4 (a) is a top view schematically showing the structure of the composite piezoelectric element 40 of a modified example of this embodiment. Figure 4 (b) is Figure 4 (a) AA-direction sectional view, Figure 4 (c) is Figure 4 (a) is a BB-direction cross-sectional view. As shown in these figures, when viewed from above, the composite piezoelectric element 40, including the buffer portion 16, has a first electrode layer 12 formed in addition to the base film 11. Therefore, the buffer portion 16 is formed by the base film 11 and the first electrode layer 12 in a laminate.

[0090] Even when the buffer portion 16 is not formed with a base film 11, by making the Young's modulus of the buffer portion 16 lower than that of the measuring portion 15, the buffer portion 16 deforms preferentially before the measuring portion 15. Therefore, it is possible to buffer the force applied to the measuring portion 15 in the short-side direction of the strip portions 13a to 1c. Therefore, the composite piezoelectric element 40 can measure the deformation in the long-side direction of the strip portions 13a to 1c with high sensitivity and high accuracy.

[0091] (Third Implementation)

[0092] The following describes the implementation of the present invention as a tire condition measuring device equipped with a composite piezoelectric element.

[0093] Figure 5 (a) and Figure 5 (b) is a top view schematically showing the condition of the tire 60 as measured by the tire condition measuring device 50 of this embodiment, which is equipped with a composite piezoelectric element 10.

[0094] Figure 5 (a) indicates the state where the tire 60 mounted on a car or the like is not rotating. As shown in the figure, when the car is parked with the tire 60 not rotating, due to the weight of the car, the contact portion 61 of the tire 60, that is, the part in contact with the road surface 70, extends in the circumferential direction of the tire.

[0095] Figure 5 (b) indicates the state in which the tire 60, mounted on a vehicle or similar object, rotates in the direction shown by the arrow. As shown in the figure, during the rotation of the tire 60 while the vehicle is in motion, the contact patch 61, which is in contact with the road surface 70, stretches in the circumferential direction of the tire 60, while the upstream portion 62 and downstream portion 63 near the contact patch 61 contract. The rate at which the tire 60 deforms due to this periodic stretching and contraction accompanying the rotation varies depending on the state of the tire 60.

[0096] Therefore, the tire condition measuring device 50 measures the deformation rate using the composite piezoelectric element 10, thereby determining the condition of the tire 60. Examples of tire condition parameters measured using the composite piezoelectric element 10 include wear, tire tread hardness, and friction (grip condition). Furthermore, the condition of the road surface 70 can also be determined based on the condition of the tire 60. Since the deformation rate of the tire 60 can be directly determined using the composite piezoelectric element 10, the condition of the tire 60 can be easily evaluated.

[0097] Furthermore, the composite piezoelectric element 10 of the present invention can perform measurements with high sensitivity and high precision in a specific direction, thus making it suitable for measuring deformation (stretching) in specific directions such as the rotation direction (circumferential direction) and the direction orthogonal to the rotation direction of the tire 60. For example, if the long side direction (X direction, see reference) of the strip portion 13a to c of the piezoelectric layer 13 is used... Figure 1 When the composite piezoelectric element 10 is configured in a circumferential manner around the tire 60, the deformation of the tire 60 in the rotational direction can be measured with high sensitivity and high accuracy.

[0098] The condition of the tire 60 can be measured by mounting the composite piezoelectric element 10 of the tire condition measuring device 50 on the inner side of the tire 60 (opposite to the contact surface of the road surface 70). For example, the composite piezoelectric element 10 can be attached to the tire 60 using an adhesive such as epoxy resin, and the tire condition measuring device 50 can be installed.

[0099] The information related to the condition of the tire 60 obtained from the tire condition measuring device 50 can be used alone or in combination with information obtained from other devices. Examples of such other devices include a TPMS (Tire Pressure Monitoring System) for monitoring vehicle tire pressure.

[0100] (Fourth Implementation)

[0101] The following describes how the tire condition measuring device with composite piezoelectric elements is implemented as a tire sensor device with a tire sensor module and a container.

[0102] Figure 14 This is a 3D view of the tire sensor device in a separated state. Figure 15 This is a partial cross-sectional perspective view showing the tire sensor device installed on the tire. For example... Figure 14 As shown, the tire sensor device 100 includes a tire sensor module 80 and a container 85 capable of housing the tire sensor module 80. Figure 15 As shown, the tire sensor device 100 measures the state of the tire 60 with the tire sensor module 80 contained in the container 8 5 mounted on the inner side 64 of the tire 60.

[0103] The container 85 can deform according to the deformation of the tire 60, for example, by using a resin with a Young's modulus of about 10 MPa to 1000 MPa, which is the same as that of the tire 60. The method of mounting the container 85 to the inner side 64 of the tire 60 is not limited, and methods such as using epoxy adhesives or cyanoacrylate instant adhesives are also included.

[0104] Figure 6(a) is a cross-sectional view showing the structure of the tire sensor module according to this embodiment, schematically illustrating that... Figure 14 The tire sensor device 100 is constructed by cutting off the portion indicated by a single-dotted line and viewing the cross section along the AA direction. Figure 6 (b) is Figure 6 (a) BB-direction sectional view.

[0105] The tire sensor module 80 includes a sheet-shaped piezoelectric sensor 81, a control unit 82, and a buffer unit 83. The piezoelectric sensor 81 converts the deformation (deformation speed) occurring in the tire 60 into voltage, thereby controlling the tire 60 (refer to...) Figure 15 Electrical detection is performed by measuring the deformation of a piezoelectric element. For example, a piezoelectric element can be formed by two electrodes sandwiching a piezoelectric element, enabling the use of devices with... Figures 1-4 The piezoelectric sensor with the same structure as the composite piezoelectric element shown is called piezoelectric sensor 81. Piezoelectric sensor 81 detects the deformation of tire 60 via a container 85 that can follow the deformation of tire 60. Piezoelectric sensor 81 is electrically connected to and controlled by the control unit 82 of tire sensor module 80.

[0106] The piezoelectric sensor 81 deforms in response to the tire 60, thereby directly detecting the condition of the tire 60. Examples of objects detected (measured) by the piezoelectric sensor 81 include tire wear, tire tread hardness, and friction (grip condition). Furthermore, the piezoelectric sensor 81 can also measure the road surface 70 (see reference) based on the condition of the tire 60. Figure 5 ) state.

[0107] The substrate 821 of the control unit 82, the communication unit 822, and the power supply 823 are sealed with rigid resin 824. The Young's modulus of the control unit 82 refers to the Young's modulus of the portion constituting the housing of the control unit 82; therefore, the Young's modulus of the rigid resin 824 is the Young's modulus of the control unit 82. Furthermore, if the control unit 82 is not sealed with rigid resin 824, the Young's modulus of the component with the largest Young's modulus among the components where the piezoelectric sensor 81 is installed is set as the Young's modulus of the control unit 82. However, the substrate 821, communication unit 822, and power supply 823 constituting the control unit 82 are generally designed to have a Young's modulus equivalent to that of the rigid resin 824.

[0108] The substrate 821 includes an arithmetic processing unit, a storage unit, etc., and performs various calculations such as processing the measurement results of the piezoelectric sensor 81, as well as controlling the tire sensor module 80. Sensors other than the piezoelectric sensor 81, such as magnetic sensors or acceleration sensors, and magnets may also be provided on the substrate 821.

[0109] The communication unit 822 transmits the measurement results of the tire sensor module 80 to an external device via wireless communication, or receives input to the arithmetic processing unit in the board 821 from an external device. Examples of external devices include electronic circuitry units (ECUs) that control various systems related to the automobile, mobile electronic devices such as smartphones located in the automobile, and server devices connected via wireless communication lines.

[0110] Power supply 823 is a battery or similar device that supplies power to the tire sensor module 80.

[0111] The rigid resin 824 is used to protect the substrate 821, communication unit 822, and power supply 823 of the control unit 82. It is a resin that is harder than the container 85 (with a higher Young's modulus), for example, with a Young's modulus of about 1 GPa to 5 GPa. Therefore, if a piezoelectric sensor 81 is installed in the control unit 82 and sealed with the rigid resin 824, the deformation of the piezoelectric sensor 81 is hindered by the rigid resin 824. That is, if the sheet-like piezoelectric sensor 81 is sealed together with the substrate 821, communication unit 822, and power supply 823 by the rigid resin 824, the deformation following the tire 60 is restricted by the rigid resin 824, making it difficult to detect the deformation of the tire 60 with high sensitivity.

[0112] Therefore, the tire sensor module 80 provides a buffer section 83 between the piezoelectric sensor 81 and the control unit 82. By providing the buffer section 83, the piezoelectric sensor 81 can easily deform in response to the deformation of the tire 60. Figure 6 (a) and Figure 6 In the embodiment shown in (b), the control unit 82 includes a retaining portion 82R that protrudes in an annular shape along the outer peripheral surface that contacts the container 85. Furthermore, a sheet-like piezoelectric sensor 81 is provided such that its end portion 82E contacts and surrounds the circumference of the circular piezoelectric sensor 81. Thus, most of the space occupied between the piezoelectric sensor 81 and the control unit 82 functions as a buffer portion 83, preventing the piezoelectric sensor 81 from easily deforming along with the tire 60. Additionally, since the retaining portion 82R surrounds the piezoelectric sensor 81, it can stably hold the piezoelectric sensor 81 in a predetermined position. However, the retaining portion 82R only needs to maintain the shape of the piezoelectric sensor 81; for example, it can be configured such that the retaining portion 82R is rod-shaped and extends along... Figure 6 The retaining portion 82R shown in (b) is arranged in a circular pattern with multiple ends 82E that are in contact with the piezoelectric sensor 81.

[0113] Thus, by providing a buffer section 83 between the piezoelectric sensor 81 and the control unit 82, thereby... Figure 6 As shown by the dashed line in (a), the piezoelectric sensor 81 does not interfere with the control unit 82 and can follow the tire 60 (see reference). Figure 15 The tire 60 is deformed by the deformation of the piezoelectric sensor 81. That is, in the tire sensor module 80, by providing a buffer part 83 between the piezoelectric sensor 81 and the control unit 82, the deformation of the piezoelectric sensor 81 becomes easy, and the deformation of the tire 60 can be detected with high sensitivity.

[0114] The piezoelectric sensor 81 measures the periodic deformation that accompanies the rotation of the tire 60 (see reference). Figure 5 of (a), Figure 5 However, situations may occur where excessive force is applied instantaneously to the tire 60, such as when the tire 60 runs over a foreign object. In such cases, applying excessive force to the control unit 82 of the tire sensor module 80 may cause a malfunction.

[0115] In the tire sensor module 80, a buffer section 83 provided between the piezoelectric sensor 81 and the control unit 82 suppresses excessive force applied to the control unit 82. For example, if the deformation of the tire 60 when it runs over a foreign object converges within the range of the buffer section 83, excessive force will not be applied to the control unit 82. Furthermore, even if the deformation of the tire 60 exceeds the range of the buffer section 83, the force applied to the control unit 82 can be reduced by the buffer section 83. In this way, the buffer section 83 facilitates the deformation of the piezoelectric sensor 81 and suppresses excessive force applied from the tire 60 to the control unit 82, preventing malfunction of the control unit 82, thereby improving the reliability of the tire sensor module 80.

[0116] From the viewpoint of highly sensitively detecting tire deformation 60 and improving the reliability of the tire sensor module 80, the height h of the buffer portion 83 is preferably 2 mm or more, more preferably 5 mm or more. Furthermore, from the viewpoint of miniaturizing the tire sensor module 80, the height h of the buffer portion 83 is preferably 5 mm or less, more preferably 3 mm or less. Therefore, to balance reliability and miniaturization, it is preferable to set the height h of the buffer portion 83 to approximately 2 mm to 3 mm. Additionally, as... Figure 6 As shown in (a), the height h of the buffer section 83 refers to the distance between the piezoelectric sensor 81 and the control section 82. When the distance between the two is not constant, it refers to the distance of the closest part.

[0117] Figure 7This is a cross-sectional view showing a modified example of the tire sensor module and tire sensor device. As shown in this figure, the tire sensor device 100 may also have a container-side fixing member 87 on the inner bottom surface 86 of the container 85, which is in contact with the piezoelectric sensor 81, to hold the piezoelectric sensor 81. The container-side fixing member 87 can more stably maintain the contact between the piezoelectric sensor 81 and the inner bottom surface 86 of the container 85. Therefore, by maintaining a constant positional relationship between the piezoelectric sensor 81 and the inner bottom surface 86, the piezoelectric sensor 81 can detect the deformation of the tire 60 with high accuracy. Figure 7 As shown, when the piezoelectric sensor 81 is held by the container-side fixing member 87, the annular holding part 82R for holding the piezoelectric sensor 81 is not required (see reference). Figure 6 of (a), Figure 6 (b)

[0118] Figure 13 (a) and Figure 13 (b) represents the piezoelectric sensor of the present invention. Figure 13 (a) is a top view. Figure 13 (b) is Figure 13 (a) is a cross-sectional view along the CC direction. The piezoelectric sensor 81 is sheet-like, as shown in Figure 1. Figure 13 As shown in (a), the shape is circular when viewed from above relative to the surface of the tire 60, i.e., when viewed from the normal direction of the sheet. By making the shape circular when viewed from above, the measurement conditions are the same regardless of the orientation of the piezoelectric sensor 81. Therefore, the output becomes the same regardless of the direction of deformation of the piezoelectric sensor 81, as long as the deformation rate and magnitude are the same. Thus, confirming the installation orientation during the installation operation of the tire 60 becomes easier (see reference). Figure 15 That is, even if the tire sensor module 80 (piezoelectric sensor 81) is slightly deviated from its orientation relative to the tire 60 when inserted into or installed into the container 85, the output is unlikely to deviate significantly. Assuming the piezoelectric sensor 81 is rectangular, its sensitivity to deformation along the shorter side of the rectangle is higher than its sensitivity to deformation along the longer side. Therefore, if the installation orientation of the tire sensor module 80 (piezoelectric sensor 81) relative to the tire 60 is offset, the output will be easily affected.

[0119] The size of the piezoelectric sensor 81 is not particularly limited, but from the viewpoint of obtaining high output, the diameter is preferably 5 mm or more, more preferably 8 mm or more. From the viewpoint of miniaturization, the diameter is preferably 20 mm or less, more preferably 15 mm or less.

[0120] In this embodiment, a piezoelectric sensor that is circular when viewed from above in the direction normal to the sheet has been described; however, the shape of the piezoelectric sensor is not limited to this. For example, the piezoelectric sensor used in the above embodiment may also be used. Figures 1-4 The composite piezoelectric element shown serves as a piezoelectric sensor. By using a composite piezoelectric element with a buffer section, a tire sensor module with good sensitivity in a specified direction can be formed.

[0121] (Fifth Implementation)

[0122] Figure 8 This is a cross-sectional view showing the tire sensor module and tire sensor device of this embodiment. The tire sensor module 90 of the tire sensor device 200 of this embodiment differs from the tire sensor module 80 of the tire sensor device 100 of the first embodiment in that the buffer portion 83 has a soft portion 93 with a Young's modulus smaller than that of the hard resin 824 of the control portion 82. In this invention, the softness of the material is evaluated by Young's modulus; the smaller the Young's modulus, the softer it is (the larger the Young's modulus, the harder it is).

[0123] The flexible portion 93 provided in the buffer portion 83 is more flexible than the hard resin 824. Therefore, compared to the case where it is sealed with hard resin 824, the piezoelectric sensor 81 is more prone to deformation with the deformation of the tire 60. In addition, by providing the flexible portion 93 in the buffer portion 83, the effect of protecting the control unit 82 is also improved. Furthermore, by making the flexible portion 93 in contact with both the piezoelectric sensor 81 and the control unit 82, the relative positional relationship between the piezoelectric sensor 81 and the control unit 82 can be maintained, thus allowing the measurement conditions of the piezoelectric sensor 81 to be set to a predetermined state to improve measurement accuracy.

[0124] The material used in the flexible part 93 only needs to be softer than the control part 82, and preferably softer than the container 85. Examples include polyurethane resin, natural rubber, synthetic rubber, butadiene rubber, butyl rubber, ethylene butadiene rubber, nitrile rubber, silicone rubber, and acrylic rubber. The Young's modulus of the flexible part 93 is preferably 10 MPa to 1000 MPa, more preferably 10 MPa to 500 MPa, and even more preferably 10 MPa to 100 MPa.

[0125] Figure 9This is a cross-sectional view showing a modified example of the tire sensor module and tire sensor device according to this embodiment. As shown in the figure, the tire sensor device 200 may also have a container-side fixing member 88 for holding the piezoelectric sensor 81 on the inner bottom surface 86 of the container 85, which is in contact with the piezoelectric sensor 81. The container-side fixing member 88 maintains the contact between the piezoelectric sensor 81 and the inner bottom surface 86 of the container 85. Therefore, the piezoelectric sensor 81 can detect the deformation of the tire 60 with high sensitivity via the inner bottom surface 86 of the container 85. Furthermore, Figure 9 The container side fastener 88 shown is... Figure 7 Unlike the container-side fixture 87, which penetrates the piezoelectric sensor 81, the piezoelectric sensor 81 is positioned and held along the surface of the container-side fixture 88.

[0126] Figure 10 (a) and Figure 10 Figure (b) is a cross-sectional view showing a modified example of the structure of the tire sensor module of this embodiment. As shown in the figure, the buffer portion 83 of the tire sensor device 200 may also include a gap portion 94 without the flexible portion 93. By including the gap portion 94, the flexible portion 93 is more easily deformed within the buffer portion 83, so the piezoelectric sensor 81 can easily deform following the deformation of the tire 60, thereby improving the detection sensitivity of the tire sensor module 90. In addition, by forming a portion pressed by the flexible portion 93 and a portion not pressed on the piezoelectric sensor 81, the detection sensitivity of the tire sensor module 90 is further improved.

[0127] like Figure 10 As shown in (b), the piezoelectric sensor 81 is circular when viewed from above, making it suitable for detecting tire 60 deformation regardless of orientation. Furthermore, as shown in the figure, the gap 94 is provided with a uniform width to surround the outer periphery of the flexible portion 93. With this structure, the piezoelectric sensor 81 can easily track tire 60 deformation in all directions, resulting in good detection sensitivity of the tire sensor module 90 regardless of the deformation direction.

[0128] Figure 11 Figure (a) is a cross-sectional view showing a modified example of the structure of the tire sensor module of this embodiment. As shown in this figure, the flexible portion 93 of the tire sensor module 90 may also have a slit 95. The slit 95 refers to an elongated gap that breaks the flexible portion 93. By having the slit 95, and the gap portion 94 (see reference 94) Figure 10 of (a), Figure 10 Similarly, the soft part 93 is easily deformable within the buffer part 83, thus improving the detection sensitivity of the tire sensor device 200.

[0129] like Figure 11As shown in (b), by arranging multiple slits 95 parallel to each other in one direction, the ease of deformation of the flexible part 93 can be varied depending on the direction in which the slits 95 are arranged. Therefore, even though the piezoelectric sensor 81 appears circular when viewed from above, the detection sensitivity can be adjusted by the direction of deformation of the tire 60. For example, if the direction of rotation of the tire 60 (refer to...) Figure 5 If the tire sensor device 200 is positioned orthogonally to the long side direction of the slit 95 (b), the flexible part 93 can easily extend and retract along the rotation direction of the tire 60. Therefore, a tire sensor module 90 with good detection sensitivity for deformation in the rotation direction of the tire 60 can be obtained.

[0130] like Figure 10 of (a), Figure 10 (b) Figure 11 (a) and Figure 11 As shown in (b), by providing the gap 94 and slit 95, the flexible portion 93 within the buffer portion 83 is more easily deformed. Therefore, the piezoelectric sensor 81 more easily follows the deformation of the tire 60, and the detection sensitivity of the piezoelectric sensor 81 is improved. Furthermore, the structure of the gap 94 and slit 95 allows the detection sensitivity of the piezoelectric sensor 81 to be the same regardless of the direction of tire 60 deformation, or to change according to the direction of deformation. Moreover, the shape and number of the slits 95 provided in the gap 94 and flexible portion 93 are not limited to the examples described above. For example, if a grid structure is adopted in which the flexible portion 93 is arranged with multiple parallel slits 95 orthogonally, the detection sensitivity of the piezoelectric sensor 81 is the same regardless of the direction of tire 60 deformation.

[0131] Figure 12 This is a cross-sectional view showing a modified example of the tire sensor module and tire sensor device according to this embodiment. As shown in the figure, the control unit 82 of the tire sensor module 90 has a fixing member 84 on the buffer portion 83 side. By inserting the fixing member 84 into the slit 95 of the flexible portion 93, changes in the positional relationship between the flexible portion 93 and the piezoelectric sensor 81 and the control unit 82 can be suppressed. Therefore, the measurement conditions of the piezoelectric sensor 81 can be maintained constant, and the deformation of the tire 60 can be detected with high accuracy.

[0132] Industrial utilization potential

[0133] This invention is useful as a device for measuring the condition of tires, such as wear, and the condition of road surfaces.

[0134] Explanation of reference numerals in the attached figures

[0135] 10, 20, 30, 40: Composite piezoelectric elements

[0136] 11: Base membrane

[0137] 12, 14: First electrode layer

[0138] 121, 141: Terminal section

[0139] 13: Piezoelectric layer

[0140] 13a, 13b, 13c: Band-like portion

[0141] 15: Measurement Department

[0142] 16: Buffer section

[0143] 17: Incision area

[0144] 50: Tire Condition Measurement Device

[0145] 60: Tires

[0146] 61: Grounding part

[0147] 62: Upstream

[0148] 63: Downstream

[0149] 64: Inner side

[0150] 70: Road surface

[0151] 80, 90: Tire sensor module

[0152] 81: Piezoelectric sensor

[0153] 82: Control Department

[0154] 82R: Retention section

[0155] 82E: End

[0156] 821: Substrate

[0157] 822: Ministry of Communications

[0158] 823: Power Supply

[0159] 824: Hard resin

[0160] 83: Buffer section

[0161] 84: Fasteners

[0162] 85: Container

[0163] 86: Bottom inner side

[0164] 87, 88: Container side fasteners

[0165] 93: Soft part

[0166] 94: Void

[0167] 95: Slit

[0168] 100, 200: Tire sensor device (tire condition measurement device)

[0169] h: height

[0170] L: Length

[0171] W1, W2: Width

Claims

1. A tire sensor module, comprising: A sheet-like piezoelectric sensor capable of measuring tire deformation; and A control unit capable of processing the measurement results from the piezoelectric sensor. The tire sensor module is characterized in that... A buffer section is provided between the piezoelectric sensor and the control unit. The buffer section has a soft portion with a smaller Young's modulus compared to the control section. The flexible part is in contact with the piezoelectric sensor and the control unit. The flexible part has a slit. The slit is arranged such that its length direction is orthogonal to the rotation direction of the tire.

2. The tire sensor module according to claim 1, wherein, The Young's modulus of the flexible portion is 10 MPa to 1000 MPa.

3. The tire sensor module according to claim 1, wherein, The buffer portion includes the soft portion and the gap portion.

4. The tire sensor module according to claim 1, wherein, The control unit has a fixing component. The fastener is inserted into the slit.

5. The tire sensor module according to claim 1, wherein, The control unit includes a communication unit.

6. The tire sensor module according to claim 1, wherein, The control unit includes a magnetic sensor, an accelerometer, or a magnet.

7. A tire sensor device, characterized in that, have: The tire sensor module according to claim 1; and A container capable of elastic deformation is used to enclose the tire sensor module and is fixed to the inside of the tire.

8. The tire sensor device according to claim 7, wherein, The container has a container-side fixing member for holding the piezoelectric sensor of the tire sensor module in a predetermined position.

9. The tire sensor device according to claim 8, wherein, The tire sensor module is as follows: The buffer section has a soft portion with a smaller Young's modulus compared to the control section. The flexible part is in contact with the piezoelectric sensor and the control part.

Images