JP6463173B2 - Acceleration acquisition device, tire, and tire manufacturing method - Google Patents

Description

  The present invention relates to an acceleration acquisition device, a tire, and a tire manufacturing method.

  Conventionally, the vibration acceleration of a tire is detected by an acceleration sensor attached to the inside of the tire of an automobile, the detected vibration acceleration is wirelessly transmitted to an in-vehicle analysis device, and the vibration acceleration transmitted to the in-vehicle analysis device is analyzed in real time. There is a technique for determining a tire wear state and a road surface state (dryness, semi-humidity, sherbet, snow accumulation, snow pressure, freezing, etc.). The acceleration sensor is driven by the supply of electric power generated by a generator mounted on the inside of the tire, like the acceleration sensor.

  For example, a vibration generator may be used as the generator. In this case, the acceleration sensor and the vibration generator are preferably integrated in order to reduce the size.

  For example, Patent Document 1 discloses a device in which a vibration generator and an acceleration sensor are integrated.

JP 2012-206630 A

  When the acceleration sensor and the vibration generator are integrated, the vibration of the vibration generator is transmitted to the acceleration sensor, and the signal waveform of the vibration acceleration detected by the acceleration sensor is disturbed, so there is a possibility that the vibration acceleration cannot be obtained with high accuracy. . In this case, it is conceivable that the influence of vibration of the vibration generator is prevented from being transmitted to the acceleration sensor by setting the resonance frequency of the vibration generator outside the frequency range of vibration acceleration detected by the acceleration sensor. .

  However, for example, when the tire is rotated from side to side, the rotation direction is reversed. Therefore, when the position of the acceleration sensor is biased with respect to the apparatus in which the vibration generator and the acceleration sensor are integrated, When the rotation direction is reversed, the behavior of the acceleration sensor changes, and the detected vibration acceleration signal waveform may change.

  The present invention has been made in view of the above-described facts, and an object thereof is to provide an acceleration acquisition device, a tire, and a tire manufacturing method that can accurately acquire vibration acceleration even when the tire is rotated. To do.

In order to achieve the above object, an acceleration acquisition device according to a first aspect of the present invention includes an acceleration sensor that is disposed at the center in the width direction and the center in the length direction of the device and that detects vibration acceleration of the tire, and the vibration of the tire. A vibration generator that generates power and whose resonance frequency is outside the use frequency range of vibration acceleration detected by the acceleration sensor, and a vibration direction of the vibration generator and a detection direction of the vibration acceleration of the acceleration sensor, angle formed is Ru der and 110 degrees at 70 degrees.
According to a second aspect of the present invention, there is provided an acceleration acquisition device according to the present invention, which is arranged at the center in the width direction and the center in the length direction of the device itself, detects an acceleration of tire vibration, generates power by vibration of the tire, and has a resonance frequency of the acceleration. An even number of vibration generators outside the operating frequency range of vibration acceleration detected by the sensor, and the even number of vibration generators are divided into the same number, and the acceleration is generated by the same number of vibration generators. Sensor is sandwiched.

In addition, as described in Claim 3 , it is good also as a structure whose resonance frequency of the said vibration generator is a frequency below 500 Hz, or a frequency higher than 2 kHz.

A tire according to a fourth aspect of the present invention is a tire in which the acceleration acquisition device according to any one of the first to third aspects is disposed at the center in the width direction inside the tire.

A method for manufacturing a tire according to a fifth aspect of the invention includes a step of attaching the acceleration acquisition device according to any one of the first to third aspects to the center in the width direction inside the tire.

  According to the present invention, there is an effect that vibration acceleration can be obtained with high accuracy even when a tire is rotated.

It is a perspective view of an acceleration acquisition device. It is sectional drawing of a tire. It is a top view of the inner side of a tire. It is a block diagram of an acceleration acquisition apparatus. It is a block diagram of a vibration generator. It is a side view of an acceleration acquisition device. It is a wave form diagram of vibration acceleration in case the resonant frequency of a vibration generator is 50 Hz. It is a figure which shows the power spectrum of the vibration acceleration in case the resonant frequency of a vibration generator is 50 Hz. It is a waveform diagram of vibration acceleration when the resonance frequency of the vibration generator is 870 Hz. It is a figure which shows the power spectrum of the vibration acceleration in case the resonant frequency of a vibration generator is 870 Hz. It is a waveform diagram of vibration acceleration when the vibration direction of the vibration generator and the detection direction of vibration acceleration of the acceleration sensor are orthogonal to each other. It is a figure which shows the power spectrum of the vibration acceleration at the time of making the vibration direction of a vibration generator orthogonal to the detection direction of the vibration acceleration of an acceleration sensor.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a perspective view of an acceleration acquisition device 10 according to the present embodiment. As shown in FIG. 1, the acceleration acquisition device 10 includes two vibration generators 12 </ b> A and 12 </ b> B and an acceleration detection unit 14. The vibration generators 12A and 12B and the acceleration detector 14 are integrated by being attached to the metal attachment portion 16 in a state where the acceleration detector 14 is sandwiched between the vibration generators 12A and 12B. The attachment portion 16 is fixed to the pedestal 18. In the present embodiment, as an example, the vibration generators 12A and 12B and the acceleration detector 14 have the same outer size (vertical × horizontal × height).

  In the present embodiment, the configuration in which the acceleration sensor 20 is sandwiched between the two vibration generators 12A and 12B will be described. However, the number of vibration generators may be more than two. For example, an even number of vibration generators may be divided into the same number, and the acceleration sensor 20 may be sandwiched between the same number of vibration generators.

  Moreover, it is good also as a structure which integrated the single vibration generator and the acceleration sensor 20, and also in the case of the structure which integrated the several vibration generator and the acceleration sensor 20, the acceleration sensor 20 with several vibration generators. It is good also as a structure which does not pinch | interpose.

  As shown in FIG. 2, the acceleration acquisition device 10 is attached to the inside of the tire T with, for example, an adhesive or the like after the tire T is manufactured with the bottom surface of the base 18 as an attachment surface. Specifically, as illustrated in FIG. 2, the acceleration acquisition device 10 is attached to the center of the tire T in the width direction (Y direction center), that is, the center line CL of the tire. 3, the acceleration acquisition device 10 includes a vibration generator 12A, an acceleration detection unit 14, and a vibration generator along the width direction (Y direction) of the tire T. It is attached to the inside of the tire T so as to be in the order of 12B. Note that the pedestal 18 may be omitted, and the attachment portion 16 may be directly attached to the inside of the tire T.

  In FIG. 4, the block diagram of the acceleration acquisition apparatus 10 was shown. As shown in FIG. 4, the acceleration detection unit 14 includes an acceleration sensor 20 and a transmission unit 22, and is driven by the supply of power generated by the vibration generators 12 </ b> A and 12 </ b> B.

  As shown in FIG. 5, the vibration generator 12A includes a magnet 24 and two coil springs 26 and 28 as an example. Thus, the magnet 24 is supported by the two coil springs 26 and 28 and vibrates in the Z direction as an example.

  In the vibration power generator 12 </ b> A, the magnet 24 vibrates with the vibration of the tire T to which the acceleration acquisition device 10 is attached, and electric power is generated by electromagnetic power generation in which an electromotive force is generated in the coil 25 disposed around the magnet 24. The vibration generator 12A includes a rectifier and a capacitor (not shown), and the generated power is rectified by the rectifier and stored in the capacitor. When the voltage of the capacitor becomes equal to or higher than a predetermined threshold, power is output to the acceleration detection unit 14. Since the vibration generator 12B has the same configuration as the vibration generator 12A, the description thereof is omitted. The electric power output from the vibration generators 12 </ b> A and 12 </ b> B is accumulated in the capacitor and output to the acceleration detection unit 14.

  In the present embodiment, the case of the configuration including the magnet 24 and the coil 25 is described as a configuration for converting vibration into electric power. However, the configuration for converting vibration into electric power is not limited to this, and various known methods can be used. Can be used. For example, a configuration including a piezoelectric element and a cantilever may be configured such that the cantilever is bent and vibrated in accordance with the surrounding vibration to generate an electric charge on the electrode of the piezoelectric element.

  As an example, the acceleration sensor 20 detects vibration acceleration in the Z direction in FIG. As the acceleration sensor 20, for example, an acceleration sensor using MEMS (Micro Electro Mechanical Systems) technology is used. Further, as shown in FIG. 3, the acceleration sensor 20 is arranged at the center in the length direction (Y direction center) of the acceleration acquisition device 10, and as shown in FIG. (Center in the X direction).

  In addition, the acceleration sensor 20 is preferably installed on the side close to the mounting portion 16 and the pedestal 18 (the tire radial direction outer side of the tire T). This is because the vibration sensor provided in the acceleration sensor 20 is preferably installed at a position close to the belt in the tire T in order to accurately detect the vibration accompanying the rolling of the tire. Further, it is preferable because the influence of the moment due to the angle change of the acceleration sensor 20 can be eliminated when the tire T is in contact with the ground.

  As shown in FIG. 4, the transmission unit 22 wirelessly transmits the vibration acceleration detected by the acceleration sensor 20 to, for example, an in-vehicle analysis device 30 installed in a vehicle cabin. The in-vehicle analysis device 30 determines at least one of a tire wear state and a tire road surface state based on the received vibration acceleration.

  Here, the vibration direction of the magnets 24 of the vibration generators 12A and 12B and the direction in which the acceleration sensor 20 detects vibration acceleration are both in the Z direction. In this case, when the resonance frequency of the vibration generators 12A and 12B is within the use frequency range of the vibration acceleration detected by the acceleration sensor 20, the vibration of the vibration generators 12A and 12B is detected by the acceleration sensor 20. The signal waveform may be adversely affected and vibration acceleration may not be detected accurately.

  Therefore, in this embodiment, the resonance frequencies of the vibration generators 12A and 12B are set so that the resonance frequencies of the vibration generators 12A and 12B are outside the use frequency range of the vibration acceleration of the acceleration sensor 20. Specifically, since the resonance frequency depends on the mass m of the magnet 24 and the spring constant k of the coil springs 26 and 28, the resonance frequency of the vibration generators 12 </ b> A and 12 </ b> B is the use frequency of vibration acceleration detected by the acceleration sensor 20. The mass m of the magnet 24 of the vibration generators 12A and 12B and the spring constant k of the coil springs 26 and 28 are set so as to be out of the range.

  For example, when determining the road surface state of the tire in the in-vehicle analysis device 30, the frequency of vibration acceleration detected by the acceleration sensor 20 is, for example, several hundred Hz to several tens kHz as described in Japanese Patent No. 4817753. Are used. In the present embodiment, it is assumed that a frequency of 500 Hz to 2 kHz is used as an example when the vehicle-mounted analyzer 30 determines at least one of a tire wear state and a road surface state. Therefore, in the present embodiment, as an example, the mass m of the magnet 24 and the coil spring 26 of the vibration generators 12A and 12B are set so that the resonance frequency of the vibration generators 12A and 12B is a frequency lower than 500 Hz or a frequency higher than 2 kHz. 28 spring constant k is set. In addition, in the case where the resonance frequency is less than 500 Hz and the case where the resonance frequency is higher than 2 kHz, the frequency of less than 500 Hz increases the amount of power generation. Therefore, the resonance generators 12A and 12B have a resonance frequency less than 500 Hz. It is preferable to set the mass m of the magnet 24 and the spring constants k of the coil springs 26 and 28 of the vibration generators 12A and 12B.

  By the way, the tire T is often rotated during use in order to avoid uneven wear. For example, when the tire T is rotated left and right, the rotation direction is often reversed, and the position of the acceleration sensor 20 is biased with respect to at least one of the width direction and the length direction of the acceleration acquisition device 10. When the rotation direction is reversed, the behavior of the acceleration sensor 20 changes, and the detected vibration acceleration signal waveform changes. On the other hand, in this embodiment, the acceleration sensor 20 is arrange | positioned in the width direction center (Y direction center) and the length direction center (X direction center) of the acceleration acquisition apparatus 10. The acceleration detection unit 14 is sandwiched between two vibration generators 12A and 12B. For this reason, even when the tire T is rotated left and right and the rotation direction is reversed, the behavior of the acceleration sensor 20 can be prevented from changing before and after the rotation of the tire T, and the accuracy is improved. Vibration acceleration can be detected.

  In the present embodiment, as an example of the case where the resonance frequency of the vibration generators 12A and 12B is outside the use frequency range of the vibration acceleration detected by the acceleration sensor 20, the resonance frequency of the vibration generators 12A and 12B. The case where the mass m of the magnet 24 of the vibration generators 12A and 12B and the spring constant k of the coil springs 26 and 28 are set so that the frequency is less than 500 Hz or higher than 2 kHz has been described. Absent. For example, the vibration direction of the vibration generators 12A and 12B and the vibration acceleration detection direction of the acceleration sensor 20 are set so that the resonance frequency of the vibration generators 12A and 12B does not affect the vibration acceleration detected by the acceleration sensor 20. May be different. Specifically, the angle formed by the vibration direction of the vibration generators 12A and 12B and the detection direction of vibration acceleration of the acceleration sensor 20 is configured to be, for example, 70 degrees or more and 110 degrees or less. Preferably, for example, the vibration direction of the vibration generators 12A and 12B and the vibration acceleration of the acceleration sensor 20 are set such that the vibration direction of the vibration generators 12A and 12B is the Z direction and the vibration acceleration detection direction of the acceleration sensor 20 is the X direction. The orientations of the vibration generators 12A and 12B and the acceleration sensor 20 are set so that the angle formed with the detection direction is 90 degrees, that is, orthogonal to each other. Thereby, the resonance frequency of vibration generator 12A, 12B can be made outside the use frequency range of the vibration acceleration detected by the acceleration sensor 20. FIG.

(Example)

  The inventors of the present invention integrated a generator (hereinafter referred to as vibration generator 1) and an acceleration sensor having a configuration in which a magnet is supported by a coil spring to vibrate, similarly to the vibration generators 12A and 12B according to the present embodiment. An acceleration acquisition device (hereinafter referred to as acceleration acquisition device A), a generator (hereinafter referred to as vibration generator 2) configured to generate electricity by vibrating a metal cantilever, and an acceleration acquisition device (acceleration acquisition device B) integrated with an acceleration sensor; An acceleration acquisition device (hereinafter referred to as acceleration acquisition device C) using a battery instead of a vibration generator was manufactured. The resonance frequency of the vibration generator 1 is 50 Hz, and the resonance frequency of the vibration generator 2 is 870 Hz. Each vibration generator was fixed so that the vibration direction was the circumferential direction. Moreover, the acceleration sensor measured the vibration acceleration of the circumferential direction using the MEMS acceleration sensor. The operating frequency range of vibration acceleration detected by the acceleration sensor is 500 Hz to 2 kHz. Further, the acceleration acquisition devices A to C were mounted on the center of the tread portion of the tire, that is, on the center line of the tire. The tire size is 225/60 / R17.

  For each of the acceleration acquisition devices A to C, the tire is rotated using a drum evaluation tester, the signal waveform of the vibration acceleration detected by the acceleration acquisition devices A to C is measured, and the power spectrum of the measured signal waveform And verified whether the influence of vibration appears in the signal waveform of vibration acceleration. The tire speed in the drum evaluation tester was set to 40 km / h.

  In the case of the acceleration acquisition device C using a battery instead of the vibration generator, it has been confirmed that the influence of vibration does not appear in the signal waveform of vibration acceleration.

  Further, in the case of the acceleration acquisition device A having a resonance frequency of 50 Hz, the signal waveform of the vibration acceleration is as shown in FIG. The solid line (with generator) in FIG. 7 is the signal waveform of the vibration acceleration detected by the acceleration acquisition device A, and the broken line (without generator) is the vibration detected by the acceleration acquisition device without the vibration generator, that is, the acceleration acquisition device C. It is a signal waveform of acceleration.

  FIG. 8 shows the power spectrum of the detected vibration acceleration signal waveform. The solid line (acceleration without generator) in FIG. 8 is the vibration acceleration signal waveform detected by the acceleration acquisition device C, and the broken line (acceleration with generator) is the vibration acceleration signal waveform detected by the acceleration acquisition device A. As shown in FIG. 8, the vibration acceleration power spectrum detected by the acceleration acquisition device A and the acceleration acquisition device C detect the vibration acceleration in the frequency range of 500 Hz to 2 kHz that is detected by the acceleration sensor. It was found that the vibration acceleration power spectrum almost coincides with the vibration generator 1 so that the vibration generator 1 does not adversely affect the vibration acceleration signal waveform.

  Further, in the case of the acceleration acquisition device B having a resonance frequency of 870 Hz, the vibration acceleration signal waveform is as shown in FIG. FIG. 10 shows the power spectrum of the detected vibration acceleration signal waveform. As shown in FIG. 10, the power spectrum of the vibration acceleration detected by the acceleration acquisition device B particularly in the vicinity of 800 Hz to 900 Hz in the range of 500 Hz to 2 kHz, which is the use frequency range of the vibration acceleration detected by the acceleration sensor. And the power spectrum of the vibration acceleration detected by the acceleration acquisition device C are greatly different, and it has been found that the vibration of the vibration generator 2 adversely affects the signal waveform of the vibration acceleration.

  Further, FIG. 11 shows acceleration acceleration device D in which the orientation of the vibration generator and the acceleration sensor is set so that the angle formed by the vibration direction of the vibration generator and the detection direction of the vibration acceleration of the acceleration sensor is orthogonal to each other. The signal waveform of the vibration acceleration detected by performing the test in the same manner as the acquisition devices A to C is shown. FIG. 12 shows the power spectrum of the detected vibration acceleration signal waveform. As shown in FIG. 12, the vibration acceleration power spectrum detected by the acceleration acquisition device D and the acceleration acquisition device C detect the vibration acceleration in the range of 500 Hz to 2 kHz, which is the use frequency range of the vibration acceleration detected by the acceleration sensor. It was found that the vibration acceleration power spectrum almost coincides with the vibration generator, and that the vibration generator vibration does not adversely affect the vibration acceleration signal waveform.

DESCRIPTION OF SYMBOLS 10 Acceleration acquisition apparatus, 12A, 12B Vibration generator, 14 Acceleration detection part, 16 Mounting part, 18 base, 20 Acceleration sensor, 22 Transmission part, 24 Magnet, 25 Coil, 26, 28 Coil spring, 30 In-vehicle analysis apparatus

Claims (5)

An acceleration sensor that is arranged in the center in the width direction and the center in the length direction of the device and detects vibration acceleration of the tire,
A vibration generator that generates power by vibration of a tire and whose resonance frequency is outside the use frequency range of vibration acceleration detected by the acceleration sensor;
Equipped with a,
An acceleration acquisition apparatus , wherein an angle formed by a vibration direction of the vibration generator and a detection direction of the vibration acceleration of the acceleration sensor is 70 degrees or more and 110 degrees or less . An acceleration sensor that is arranged in the center in the width direction and the center in the length direction of the device and detects vibration acceleration of the tire,
An even number of vibration generators that generate power by vibration of a tire and whose resonance frequency is outside the use frequency range of vibration acceleration detected by the acceleration sensor;
With
An acceleration acquisition device in which the even number of vibration generators are divided into the same number and the acceleration sensor is sandwiched by the same number of vibration generators . The acceleration acquisition device according to claim 1 or 2, wherein a resonance frequency of the vibration generator is a frequency lower than 500 Hz or a frequency higher than 2 kHz. A tire in which the acceleration acquisition device according to any one of claims 1 to 3 is arranged at a center in a width direction inside the tire. A tire manufacturing method including a step of attaching the acceleration acquisition device according to any one of claims 1 to 3 to a center in a width direction inside the tire.

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