JP2006258733A - Sensor mounting structure and tire condition detection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor mounting structure capable of highly accurately transmitting stress required for detection to an element and maintaining a satisfactory state of adhesion of the element almost without being affected by the surface shape of tires and provide a tire condition detection apparatus having the same. <P>SOLUTION: In the sensor mounting structure, the surface acoustic element 11 for changing response signals to input signals according to distortions which occur in the direction A1 of detection is pasted to a tire T, and reinforcing rubber 16 having a hardness higher by 5° or more at least at both end parts 11a than in its periphery is interposed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sensor attachment structure for attaching a surface acoustic wave element (SAW) sensor to a tire, and a tire condition detection device that has the sensor attachment structure and detects tire distortion, stress, and the like.

  Tire handling stability is a very important characteristic, but in general, it is often evaluated as a test driver with a specialized education. For this reason, a method for evaluating steering stability more objectively and with good reproducibility is desired, and in the evaluation method, measurement of strain and stress of the tread and the sidewall is important.

  Conventionally, there has also been a method of transmitting a detection signal wirelessly using an acceleration sensor, but the acceleration sensor can only obtain indirect information, and the so-called transmitter or power source greatly affects steering stability. Since the unsprung weight increases, it is difficult to say that substantial evaluation has been made.

  On the other hand, a surface acoustic wave element (SAW) sensor, which is a passive element (passive), has the advantage of being compact and lightweight without the need for a power source. If the distortion and stress of the tread and sidewall are directly detected, Steering stability can be evaluated. For this reason, as an application of the SAW sensor to a tire, detection of a ground contact state of the tire (for example, see Patent Document 1), an example of use as a part of the sensor (for example, see Patent Document 2), and the like have been proposed.

  However, the former detects the ground contact state and is insufficient as information for evaluating the steering stability. The latter is not suitable for evaluation of steering stability because the sensor device itself is large and has a large mass.

  Further, as a similar sensor, there is a sensor of an internal pressure alarm device, and as an example of embedding in a tire, there is a patent for embedding in a bead portion or a sidewall portion with relatively little movement (for example, see Patent Documents 3 to 4). ). In addition, since it is embed | buried in a site | part with few distortions, the adhesive force is not considered.

  Furthermore, a transponder comprising a SAW sensor, a matching circuit, and an antenna is attached to the tire, and a transmitter / receiver that transmits a drive signal to the transponder and receives a signal from the transponder is installed in the vehicle. A tire information detection device for detecting tire information is known (see, for example, Patent Document 5). In this device, as a sensor structure for detecting tire air pressure and the like, the SAW sensor element is combined with a diaphragm to form a closed space, and the other side of the sensor element is communicated with the inside of the tire, thereby A sensor structure in which a sensor element bends and deforms according to an internal pressure is disclosed.

However, this Patent Document 5 does not specifically disclose a method of measuring strain using a SAW sensor. For this reason, for example, when a SAW sensor is bonded to the tire surface and the distortion of the tread or sidewall is measured directly, the tire has complicated irregularities such as tread pattern, side design, and air vent groove on the inner surface. Therefore, it is difficult to accurately measure the originally generated distortion due to the locally complicated distortion. In addition, since the SAW sensor element is small and extremely hard compared to rubber, when strain is applied, local strain and stress increase, and as a result, the adhesive interface with the SAW sensor peels off or the SAW sensor falls off. There was a problem.
Special Table 2003-526560 JP 2003-285612 A JP 2004-58997 A JP 2004-82775 A JP 2004-203165 A

  Therefore, the object of the present invention is to be less affected by the surface shape of the tire, can transmit stress necessary for detection to the element with high accuracy, and can maintain a good adhesion state of the element, Another object of the present invention is to provide a tire condition detection device having the sensor mounting structure.

  The above object can be achieved by the present invention as described below.

  That is, in the sensor mounting structure of the present invention, a surface acoustic wave element (hereinafter, may be abbreviated as “element” in some cases) that changes a response signal to an input signal due to a strain generated in the detection direction has a surrounding rubber at least at both ends thereof. It is characterized by being bonded to the tire while interposing a reinforcing rubber having a hardness of 5 ° or higher. In the present invention, the hardness of rubber refers to a value measured according to a JIS K6253 type A durometer hardness test.

  According to the sensor mounting structure of the present invention, at least both ends of the element are bonded to the tire while interposing a reinforcing rubber whose hardness is 5 ° or more higher than that of the surrounding rubber. Therefore, the stress required for detection can be accurately transmitted to the element. Further, the concentration of stress can be dispersed by the reinforced rubber, and the adhesion state of the element can be maintained well by preventing the adhesion interface from peeling off and the element from falling off.

  In the above, it is preferable that the reinforcing rubber is provided with a thickness of 0.5 to 1.5 mm with respect to the bottom surface of the surface acoustic wave element. Within such a thickness range, the stress required for detection can be transmitted to the element more accurately without significantly affecting the detection accuracy of the strain, and the adhesion state of the element can be avoided by avoiding stress concentration. Can be maintained well.

  Further, it is preferable that the surface acoustic wave element and the reinforcing rubber are bonded at an uneven surface. In this case, peeling of the adhesive interface and falling off of the element can be more effectively prevented by an effect of increasing the surface area due to the unevenness provided at the interface.

  Further, the elastic surface wave element and the reinforced rubber which are vulcanized and bonded in advance are arranged in an unvulcanized tire and vulcanized and bonded at the time of vulcanization of the tire, or the elastic material which has been vulcanized and bonded in advance. It is preferable that the surface wave element and the reinforcing rubber are bonded to the vulcanized tire.

  When the surface acoustic wave element and the reinforced rubber are vulcanized and bonded in advance, and this is placed in an unvulcanized tire and vulcanized and bonded when the tire is vulcanized, the structural accuracy of the composite is improved. Handleability of vulcanization adhesion to tire is greatly improved. Also, when the composite is bonded to the vulcanized tire, compared to the case where the composite is placed on an unvulcanized tire and vulcanized, the design value such as the direction of the composite due to the flow of the tire rubber at the time of vulcanization Misalignment is prevented and sensor mounting accuracy is greatly improved. Also, from the viewpoint of productivity, it is only necessary to process a normal product tire to some extent and bond the composite, which greatly improves productivity.

  On the other hand, the tire state detection device of the present invention includes a surface acoustic wave element and a responder having an antenna connected thereto and installed on the tire side, and transmits a drive signal to the responder and responds In the tire condition detection apparatus comprising a transmission / reception means installed on the vehicle body side for receiving a response signal from the vehicle body and processing the signal, the surface acoustic wave element is a response signal to the input signal due to strain generated in the detection direction. The surface acoustic wave element is bonded to a tire with a reinforcing rubber having a hardness of 5 ° or more higher than that of the surrounding rubber at least at both ends thereof.

  In the tire condition detection device of the present invention, when a drive signal is transmitted from a transmission / reception means to a transponder having a surface acoustic wave element that changes a response signal to an input signal due to strain generated in the detection direction, the input from the antenna The response signal is changed by the distortion generated in the detection direction with respect to the signal, and the distortion generated in the detection direction can be detected by receiving the signal by the transmission / reception means and processing the signal. At that time, the surface acoustic wave element is bonded to the tire while interposing a reinforcing rubber having a hardness of 5 ° or more higher than that of the surrounding rubber at least at both ends thereof. Since the load is applied to the end portion, it is difficult to be affected by the surface shape of the tire, and stress necessary for detection can be transmitted to the element with high accuracy. Further, the concentration of stress can be dispersed by the reinforced rubber, and the adhesion state of the element can be maintained well by preventing the adhesion interface from peeling off and the element from falling off.

  In the above, when the antenna is installed at a position separated by 60 ° or more in the tire circumferential direction with respect to the bonding position of the surface acoustic wave element, and when the surface acoustic wave element is positioned at the lowermost end by rotation of the tire Preferably, the antenna of the transmission / reception means is arranged at a position substantially opposite to the installation position of the antenna.

  In evaluating dynamic tire characteristics such as steering stability, distortion and stress due to input from the tire contact area are particularly important, but detection sensitivity decreases as the distance between the responder and the transmission / reception means increases. There was a problem. For this reason, after shifting the positional relationship between the antenna and the element as described above and arranging the positional relationship between the two antennas as described above, distortion and stress due to input from the tire grounding portion can be increased with higher sensitivity. Can be detected.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram illustrating an example of a tire condition detection device of the present invention, and FIG. 2 is an explanatory diagram illustrating an example of a mounting state of the tire condition detection device of the present invention. 3A and 3B are diagrams showing an example of the sensor mounting structure of the present invention, where FIG. 3A is a front sectional view and FIG. 3B is a plan view.

  First, the tire condition detection apparatus of the present invention will be described. As shown in FIG. 1, the tire state detection device of the present invention has a surface acoustic wave element 11 and an antenna 12 connected thereto, a responder 10 installed on the tire side, and the responder 10. And a transmission / reception means 20 installed on the vehicle body side for receiving the response signal from the responder 10 and processing the signal.

  The responder 10 of the present embodiment shows an example in which a matching circuit unit 13 for impedance matching between the surface acoustic wave element 11 and the antenna 12 is provided. As will be described later, the surface acoustic wave element 11 is a part that detects strain and stress generated in the tire as a change in propagation characteristics of the surface acoustic wave, and the antenna 12 is a part that transmits and receives radio signals.

  The matching circuit unit 13 is composed of elements such as a resistor, a capacitor, and a coil in order to achieve impedance matching. However, the matching circuit unit 13 is not necessary when impedance matching is achieved.

  On the other hand, the transmission / reception means 20 of this embodiment includes a transmission / reception circuit 22, an arithmetic circuit 23, and an antenna 21. The transmission / reception circuit 22 is a part that transmits the generated drive signal to the responder 10 and receives it from the responder 10. The arithmetic circuit 23 is a part that performs a calculation for processing the response signal from the responder 10 to determine the tire state.

  Transmission / reception of signals between the responder 10 and the transmission / reception means 20 is performed by wireless communication between the antennas 12 and 21.

  In the present embodiment, as shown in FIG. 2, the antenna 12 is installed at a position 60 ° or more away from the adhesion position of the surface acoustic wave element 11 in the tire circumferential direction. An example in which the antenna 21 of the transmission / reception means 20 provided on the vehicle body V is disposed at a position substantially opposite to the installation position of the antenna 12 when the wave element 11 is located at the lowermost end. That is, in this example, the angle θ between the adhesion position of the surface acoustic wave element 11 and the installation position of the antenna 12 is 60 ° or more.

  The surface acoustic wave element 11 is composed of a piezoelectric substrate, a comb-shaped electrode and a reflector formed on the surface of the piezoelectric substrate, and is connected to the matching circuit 13 via a land portion of the comb-shaped electrode, or this is resin-encapsulated together with the substrate. Stopped sealing elements are common. The comb electrode and the reflector are patterned at a constant interval. Thereby, the surface acoustic wave reflected by each reflector can be converted into a signal by the comb-shaped electrode.

  As the piezoelectric material used as the piezoelectric substrate, a material having a predetermined physical property coefficient according to a change in the state of the measurement target is applied. For example, in the case of a strain sensor, for example, a lithium niobate single crystal 128 ° rotated Y-cut substrate, crystal, lithium tantalate, lithium tetraborate, langasite, or the like can be used.

  Moreover, as a constituent material of the comb-shaped electrode and the reflector constituting the surface acoustic wave element 11, aluminum is a preferable example because it has a small electric resistance, is lightweight, and is easy to pattern, but is not limited thereto. However, copper, titanium, chromium, gold or the like may be applied, and these metals may be mixed together, various metals may be added, or a laminated structure may be used.

  It is preferable to adjust the material, width, and thickness of the thin film electrode and reflector so that inductance, capacitance, and the like according to design can be obtained. As a thin film forming method, a sputtering method, a vacuum thin film forming technique such as vapor deposition, a plating method, a paste printing method, or the like can be applied.

  Next, the principle of detecting tire distortion and the like by the surface acoustic wave element 11 will be described. When the piezoelectric substrate of the surface acoustic wave element 11 receives a change in the external environment, propagation characteristics such as the phase velocity and frequency of the surface acoustic wave propagating on the surface change. By comparing, for example, the phases of these signals, information on the external environment can be obtained.

  In the present embodiment, distortion or the like can be detected from the phase difference of the reflected waves. In this example, a method of detecting by phase comparison is used. However, in addition to this, a method of comparing delay times of reflected waves, a method of comparing deviation from a reference frequency, and the like can be applied.

  When detection is performed using a plurality of surface acoustic wave elements 11, it is necessary to determine each element 11. In this case, normally, the case where there is reflection is identified as 1 and the case where there is no reflection is identified as 0. Therefore, in order to insert N bits of information, it is possible to arrange a maximum of 2 N power reflectors.

  Next, the operation of the present embodiment configured as described above will be described. The transmission / reception means 20 transmits the pulsed drive signal generated by the transmission / reception circuit 22 to the responder 10 via the antenna 21. This drive signal is supplied to the surface acoustic wave element 11 via the antenna 12 and the matching circuit unit 13 of the responder 10. The surface acoustic wave element 11 generates a surface acoustic wave (SAW) having a wavelength corresponding to the pattern interval of the comb-shaped electrodes when a drive signal is input to the comb-shaped electrodes that are transmitting and receiving electrodes. The surface acoustic wave generated at the center of the piezoelectric substrate propagates to one end side of the piezoelectric substrate, is reflected by the reflector, and returns to the transmitting and receiving electrodes. The transmission / reception electrode detects the surface acoustic wave reflected by the reflector and converts it into an electric signal, and the converted electric signal is sent back to the transmission / reception means 20 through the matching circuit unit 13 and the antenna 12 as a response signal. The transmission / reception means 20 supplies the received response signal to the arithmetic circuit unit 23, and the arithmetic circuit unit 23 calculates information such as the magnitude of distortion from the phase difference of the response signal.

  The tire condition detection device of the present invention employs the sensor mounting structure of the present invention in such a device. That is, in the sensor mounting structure of the present invention, as shown in FIGS. 3A to 3B, the surface acoustic wave element 11 that changes the response signal to the input signal due to the strain generated in the detection direction A1 includes at least both ends thereof. 11a is a sensor mounting structure that is bonded to the tire T while interposing a reinforcing rubber 16 having a hardness of 5 ° or more higher than that of the surrounding rubber.

  In the present embodiment, as shown in FIG. 3, the surface acoustic wave element 11 is a sealing element in which the bear element B is sealed with a sealing material 11b together with the substrate 11c, and a reinforcing rubber is provided on the bottom surface and the periphery of the sealing element. An example in which 16 is present is shown. In the present invention, the reinforcing rubber 16 may be interposed outside both ends 11a of the surface acoustic wave element 11 in order to prevent the peeling of the adhesive interface and the element from falling off and to maintain a good adhesion state of the element. preferable. Moreover, when providing the reinforcement rubber 16 also in the outer side of the both ends 11a of the surface acoustic wave element 11, the width | variety of the part which protruded outside is 0.5-1.5 mm.

  First, the sealing element will be described. In the sealing element, bonding is performed on the substrate 11c with bumps or the like so that the electrode formation surface of the bear element B is on the lower side, and a gap 11d is provided between the bear element B and the substrate 11c. . In a state where the gap 11d is maintained, sealing is performed with a sealing material such as epoxy resin or phenol resin. The thickness of the gap 11d is preferably 0.3 mm or more.

  As the reinforcing rubber 16, a rubber having a hardness of 5 ° or more higher than that of the surrounding rubber is used, preferably a rubber having a hardness of 10 ° or higher, more preferably a rubber having a hardness of 15 ° or higher. When the hardness of the reinforcing rubber 16 is less than 5 ° higher than the hardness of the surrounding rubber, the effect of preventing the peeling of the adhesive interface and the element from falling off by the reinforcing rubber 16 cannot be obtained.

  The material of the reinforcing rubber 16 is not particularly limited, but it is preferable to increase the hardness by using the same type of rubber as that of the rubber in order to improve the adhesive strength with the rubber constituting the tire. For example, with respect to the sidewall rubber, this can be achieved by increasing the amount of carbon black in the same rubber compounding or decreasing the compounding amount of butadiene rubber.

  The reinforcing rubber 16 is preferably provided with a thickness t of 0.5 to 1.5 mm with respect to the bottom surface of the surface acoustic wave element 11. When the thickness t of the reinforcing rubber 16 is less than 0.5 mm, there is a tendency that the effect of preventing the peeling of the adhesion interface or the element from falling off by the reinforcing rubber 16 cannot be obtained. Moreover, when the thickness t of the reinforcing rubber 16 exceeds 1.5 mm, the sensitivity to tire distortion tends to decrease.

  The present embodiment shows an example in which the reinforcing rubber 16 is interposed on the entire bottom surface of the surface acoustic wave element 11, but the reinforcing rubber 16 is not necessary on the entire bottom surface, and the area of the bottom surface of the surface acoustic wave element 11. It is preferable that 20 to 80% of the reinforcing rubber 16 is interposed (see, for example, FIG. 4). If the area of the bottom surface is less than 20%, there is a tendency that the effect of preventing the peeling of the adhesive interface and the element from falling off by the reinforcing rubber 16 cannot be obtained.

  As a method for interposing the reinforcing rubber 16, the surface acoustic wave element 11 and the reinforcing rubber 16 are vulcanized and bonded in advance, and this is vulcanized and bonded when the tire is vulcanized, or this is applied to the vulcanized tire. And a method of simultaneously bonding the surface acoustic wave element 11, the reinforcing rubber 16, and the tire during tire vulcanization. The vulcanization adhesion between the surface acoustic wave element 11 and the reinforcing rubber 16 may be a method using rubber cement or a method of vulcanizing and joining the unvulcanized reinforcing rubber 16.

  When the surface acoustic wave element 11 and the reinforcing rubber 16 are vulcanized and bonded in advance, it is preferable that the bottom surface of the reinforcing rubber 16 is buffed and a rubber cement for vulcanization bonding is applied and vulcanized and bonded. When adhering to a vulcanized tire, it is preferable to buff the surface.

  Generally, rubber cement can be used in which various accelerators and sulfur are added to a rubber component and mixed with a solvent. Specifically, for example, 100 parts by weight of natural rubber, 43 parts by weight of carbon black (N326), 10 parts by weight of oil, 3 parts by weight of stearic acid, 1 part by weight of wax, 3 parts by weight of anti-aging agent (6C), tackifier (Cholesin) 10 parts by weight, zinc white 5 parts by weight, accelerator (DPG) 0.6 part by weight, accelerator (TBZTD) 0.3 part by weight, accelerator M 0.5 part by weight, and sulfur 3 parts by weight Thus, rubber blend A can be prepared, and rubber cement can be prepared by mixing 137 parts by weight of rubber blend A and 1100 parts by weight of rubber volatile oil.

  Vulcanization adhesion using rubber cement can be performed under the same conditions as in the vulcanization process of the tire. For example, it can be performed by heating at 105 to 125 ° C. for 0.5 to 3 hours.

  In the sensor mounting structure of the present invention, the electrode pattern forming surface of the surface acoustic wave element 11 is preferably disposed on the lower side (the tire surface side) from the viewpoint of preventing damage and dirt.

[Other Embodiments]
(1) In the above-described embodiment, an example in which an element sealed as a surface acoustic wave element is used has been described. However, in the present invention, a bare element of a surface acoustic wave element can also be used. Also in that case, it is preferable to arrange the bare element so that the electrode formation surface is on the lower side and provide a gap on the surface. At this time, the thickness of the gap is preferably 0.3 mm or more.

  (2) In the above-described embodiment, the example in which the reinforcing rubber is interposed in the entire bottom surface of the surface acoustic wave element has been shown. However, in the present invention, as shown in FIGS. A structure in which the reinforcing rubber 16 is interposed at both end portions 11a of the element 11 and the reinforcing rubber 16 is not interposed in the intermediate portion 11e of the surface acoustic wave element 11 is preferable. According to this structure, the stress required for detection can be amplified and transmitted to the surface acoustic wave element 11, and the detection sensitivity can be further improved.

  (3) In the above-described embodiment, an example in which the upper surface of the surface acoustic wave element is adhered to the tire in a state where the upper surface is exposed from the tire surface is shown. However, in the present invention, as shown in FIGS. The wave element 11 may be adhered to the tire in a state where the upper surface of the wave element 11 is not exposed from the tire surface.

  The example shown in FIG. 5 is an example in which the surface acoustic wave element 11 is bonded in a state of being embedded in the reinforcing rubber 16. In this case as well, a bare element may be used as the surface acoustic wave element 11.

  The example shown in FIG. 6 corresponds to a structure in which the reinforcing rubber 16 is not interposed in the intermediate portion 11e of the surface acoustic wave element 11 as in the embodiment shown in FIG. 16 is an example of being bonded in a state of being embedded in tire rubber. In this case as well, a bare element may be used as the surface acoustic wave element 11.

  (4) In the above-described embodiment, an example in which a rubber layer having a lower hardness than the rubber constituting the tire is not used is shown. However, in the present invention, as shown in FIG. A structure in which a low-hardness material 17 having a hardness lower than that of tire rubber (for example, a rubber hardness of 5 ° or more) is interposed without the reinforcement rubber 16 being interposed. By doing so, it is possible to reduce the strain reduction due to the reinforcing rubber 16 having a high elastic modulus and transmit it to the surface acoustic wave element 11, thereby further improving the detection sensitivity.

  (5) In the above-described embodiment, an example of a tire state detection device using only one surface acoustic wave element is shown, but in the present invention, a plurality of surface acoustic wave elements are bonded in a plurality of directions, You may make it detect simultaneously the distortion and stress of multiple directions.

  In that case, each response signal can be easily distinguished by shifting the position of the antenna on the responder side in the tire circumferential direction. In addition, in order to identify the response signal from each surface acoustic wave element, identification information may be included in the response signal itself by changing the formation position or pattern of the reflector.

  (6) In the above-described embodiment, the example in which the surface acoustic wave element and the reinforcing rubber are bonded at the flat interface is shown. However, as shown in the enlarged view of FIG. Are preferably bonded at an interface having irregularities. In this case, peeling of the adhesive interface and falling off of the element can be more effectively prevented by the effect of increasing the surface area due to the unevenness provided at the interface. In addition, as for the height of the convex part 11f provided in the surface acoustic wave element 11, 0.1-2 mm is preferable.

  (7) In the above-described embodiment, as shown in FIG. 2, the example in which the surface acoustic wave element 11, the antenna 12, and the antenna 21 of the transmission / reception means 20 are arranged has been described. It is also possible to install the antenna 21 of the transmitting / receiving means 20 outside the axle with respect to the antenna 12 installed near the center. In this case, the antenna 21 can be installed on a support mounted on the vehicle body. According to this arrangement structure, there is an effect that the strength of the signal due to the rotation of the tire is reduced.

  Examples and the like specifically showing the configuration and effects of the present invention will be described below.

(1) Surface acoustic wave device (Bear device)
As a surface acoustic wave element, a lithium niobate bare element (width 3.5 mm, length 5.5 mm, thickness 0.3 mm) was used. On the surface of the bear element, a comb electrode and a reflective electrode for inputting and outputting signals are patterned.

(2) Surface acoustic wave device (epoxy sealing)
As shown in FIG. 3, the electrode forming surface of the bear element of (1) above is placed by bonding on the substrate so as to face each other with a gap, and epoxy resin (compressed) is maintained so that the gap is maintained. An epoxy sealing element having a width of 4 mm, a length of 6 mm, and a thickness of 0.7 mm was produced by sealing at an elastic modulus of 2800 MPa.

(3) Measurement of crack generation strain According to JIS K 6251, a rubber sheet was punched into a test piece of No. 1 dumbbell, a tensile test was performed at a tensile speed of 10 mm / min, and the strain when a crack was generated was measured.

Control product
In order to form the sensor mounting structure shown in FIG. 9 using the above epoxy sealing element, the above epoxy sealing is applied to an unvulcanized rubber sheet having a general rubber composition (hardness 54 °) as a sidewall rubber of a tire. A stop element was attached and press vulcanized at 160 ° C. for 20 minutes to obtain a flat rubber sheet having a thickness of 2.5 mm. Using this, the crack generation strain was measured. The results are shown in Tables 1-3.

Example 1
In order to form the sensor mounting structure shown in FIG. 3 using the above epoxy sealing element, the thickness of the bottom part of the above epoxy sealing element is 1.0 mm, the thickness of the peripheral part is 1.7 mm, Unvulcanized reinforcing rubber (hardness after vulcanization 60 °) was attached to the epoxy sealing element so that the width was about 1 mm. This was further affixed to the same unvulcanized rubber sheet as the control product, and press vulcanized at 160 ° C. for 20 minutes to obtain a flat rubber sheet having a thickness of 2.5 mm. Using this, the crack generation strain was measured. The results are shown in Table 1.

Examples 2-3
In Example 1, a rubber sheet was prepared in the same manner as in Example 1 except that the hardness of the reinforcing rubber was changed, and crack generation strain was measured using this rubber sheet. The results are shown in Table 1.

表１の結果が示すように、周囲のゴムより硬度が5°以上高い補強ゴムを設けることにより、クラック発生歪が大きくなっており、接着界面の剥がれや素子の脱落を効果的に防止できることが判る。

As shown in the results of Table 1, by providing a reinforced rubber whose hardness is 5 ° or more higher than that of the surrounding rubber, cracking distortion is increased, and it is possible to effectively prevent peeling of the adhesive interface and falling off of the element. I understand.

Comparative Example 1
Similarly to FIG. 8, convex portions having a width of 0.3 mm and a height of 0.2 mm were formed at intervals of 0.3 mm on the bottom surface and side surfaces of the epoxy sealing element using an epoxy resin (compression elastic modulus 2800 MPa). A rubber sheet was prepared under the same conditions as the control product except that the epoxy sealing element having the unevenness was used, and crack generation strain was measured using this rubber sheet. The results are shown in Table 2.

Examples 4-5
Similarly to FIG. 8, convex portions having a width of 0.3 mm and a height of 0.2 mm were formed at intervals of 0.3 mm on the bottom surface and side surfaces of the epoxy sealing element using an epoxy resin (compression elastic modulus 2800 MPa). A rubber sheet was produced under exactly the same conditions as in Examples 2 to 3 except that the epoxy sealing element having the unevenness was used, and crack generation strain was measured using this rubber sheet. The results are shown in Table 2.

表２の結果が示すように、補強ゴムを設ける際にセンサとの界面に凹凸を設けることにより、クラック発生歪がより大きくなっており、接着界面の剥がれや素子の脱落をより効果的に防止できることが判る。

As shown in the results in Table 2, by providing unevenness at the interface with the sensor when providing the reinforced rubber, cracking distortion is greater, preventing peeling of the adhesive interface and dropping off of the element more effectively. I understand that I can do it.

Comparative Example 2
A rubber sheet was prepared under exactly the same conditions as the control product, except that the above-described bear element was used instead of the epoxy sealing element, and crack generation strain was measured using this rubber sheet. The results are shown in Table 3.

Examples 6-8
In Example 1, instead of using an epoxy sealing element, a rubber sheet was prepared under the same conditions as in Example 1 except that the above bare element was used and a reinforcing rubber having the hardness shown in Table 3 was used. Was used to measure crack generation strain. The results are shown in Table 3.

表３の結果が示すように、周囲のゴムより硬度が5°以上高い補強ゴムを設ける本発明は、ベアー素子を用いる場合でも、接着界面の剥がれや素子の脱落を効果的に防止できることが判る。

As shown by the results in Table 3, it can be seen that the present invention in which the reinforcing rubber having a hardness of 5 ° or more higher than that of the surrounding rubber can effectively prevent peeling of the adhesive interface and dropping of the element even when a bare element is used. .

The schematic block diagram which shows an example of the detection apparatus of the tire condition of this invention Explanatory drawing which shows an example of the mounting state of the detection apparatus of the tire condition of this invention It is a figure which shows an example of the sensor attachment structure of this invention, (a) is front view sectional drawing, (b) is a top view It is a figure which shows the other example of the sensor attachment structure of this invention, (a) is front view sectional drawing, (b) is a top view Front sectional view showing another example of the sensor mounting structure of the present invention Front sectional view showing another example of the sensor mounting structure of the present invention Front sectional view showing another example of the sensor mounting structure of the present invention Front sectional view showing another example of the sensor mounting structure of the present invention Front sectional view showing the sensor mounting structure in the contrast product

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Response device 11 Surface acoustic wave element 11a Both ends 12 Antenna 15 Cutting part 16 Reinforcement rubber 20 Transmission / reception means 21 Antenna A1 Detection direction B Bearer element T Tire

Claims (5)

  A surface acoustic wave element that changes the response signal to the input signal due to the strain in the detection direction is attached to the tire while interposing reinforcing rubber that is at least 5 ° harder than the surrounding rubber at both ends. Construction.   The sensor mounting structure according to claim 1, wherein the reinforcing rubber is provided with a thickness of 0.5 to 1.5 mm with respect to a bottom surface of the surface acoustic wave element.   The sensor mounting structure according to claim 1, wherein the surface acoustic wave element and the reinforcing rubber are bonded to each other at an interface having irregularities.   The surface acoustic wave element that has been pre-cured and bonded to the surface acoustic wave element and the reinforcing rubber is disposed on an unvulcanized tire and is vulcanized and bonded at the time of vulcanization of the tire, or the surface acoustic wave that has been pre-cured and bonded to the surface. The sensor mounting structure according to claim 1, wherein the element and the reinforcing rubber are bonded to a vulcanized tire. A surface acoustic wave element and a responder installed on the tire side having an antenna connected thereto, a drive signal is transmitted to the responder, and a response signal from the responder is received to process the signal. In a tire state detection device comprising transmission / reception means installed on the vehicle body side to perform,
The surface acoustic wave element changes a response signal to an input signal due to strain generated in the detection direction, and the surface acoustic wave element is made of a reinforced rubber whose hardness is 5 ° or more higher than that of the surrounding rubber at least at both ends thereof. A tire state detection device, wherein the tire state detection device is bonded to a tire while being interposed.

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