Physical quantity detection device

Abstract

A physical quantity detection device (10) detects a plurality of different physical quantities on the basis of a signal waveform that has been output. A strain sensor (3) which is one sensor element outputs a sensor signal waveform (15) having a reference level (151), a positive level where there is a change to positive with respect to the reference level (151), and a negative level where there is a change to negative with respect to the reference level (151). An estimation unit (4) uses the sensor signal waveform (15) that has been output by the strain sensor (3) to estimate a first physical quantity corresponding to a peak value (152) of the positive level, and a second physical quantity corresponding to a peak value (153) of the negative level.

Description

[Technical Field]

[0001] The present invention relates to a physical quantity detection device. [Background technology]

[0002] In recent years, in order to realize autonomous driving, tire sensor technology that detects road surface slipperiness and tire load based on information obtained from tires to provide safer driving conditions has been actively developed. Providing safer driving conditions will prevent tire problems such as tire bursts due to overloading and vehicle rollovers due to load imbalance. To build such a safety control system, it is necessary to accurately detect physical quantities such as tire load and air pressure.

[0003] Tire strain sensors can detect tire distortion and deformation, thereby detecting the amount of load acting on the tire and the amount of tire wear. This is expected to help prevent vehicle trouble and improve driving safety by detecting driving and road surface conditions.

[0004] On the other hand, strain sensors may simultaneously detect physical quantities other than load and wear (e.g., speed, temperature, air pressure, load, wear, etc.) as strain. Therefore, the sensor signal waveform that represents the results of strain detected by the strain sensor may contain components caused by these physical quantities. These components caused by physical quantities other than wear and load reduce the detection accuracy of wear and load.

[0005] Patent Document 1 discloses a conventional technique for such a detection device. Patent Document 1 describes a technique related to a strain sensor. The objective of Patent Document 1 is to "provide a method and system capable of estimating the amount of load applied to a vehicle tire," and describes the following technology: "A system and method for estimating the amount of load applied to a vehicle tire, comprising: an air pressure measurement sensor attached to the tire for measuring the air pressure level in the tire cavity; and one or more piezo film deformation measurement sensors attached to the tire sidewall. The deformation measurement sensor generates a deformation signal at the tire footprint having a signal power level indicative of the deformation level of the sidewall near the footprint contact surface. A signal power vs. load map is generated and stored that associates a predetermined range of load levels with signal power levels, corrected by tire air pressure, so that the load level can be identified from the signal power level based on the tire air pressure correction." [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-054978 Summary of the Invention [Problem to be solved by the invention]

[0007] In the technology described in Patent Document 1, the signal power level of the load sensor is corrected using the tire air pressure measured by the air pressure measurement sensor, taking into consideration that changes in tire air pressure change the signal amplitude of the load sensor. However, the detection signal of the load sensor may contain components caused by physical quantities other than air pressure. Therefore, it is believed that the technology described in Patent Document 1 has room for further improvement in the detection accuracy of the load sensor. Furthermore, the technology does not take into consideration a technology for detecting both the load amount and other physical quantities using a single sensor.

[0008] An object of the present invention is to provide a physical quantity detection device that accurately detects a plurality of physical quantities together from a sensor signal waveform that includes the plurality of physical quantities output from one sensor element. [Means for solving the problem]

[0009] A physical quantity detection device according to one aspect of the present invention is a physical quantity detection device that detects a plurality of different physical quantities based on an output signal waveform, and outputs a sensor signal waveform having a reference level, a positive level that changes to a positive side of the reference level, and a negative level that changes to a negative side of the reference level. Strain Sensor and the above Strain Sensor The sensor signal waveform output by Vehicle tire wear and the peak value of the negative level Amount of load acting on the tire and an estimation unit that estimates The strain sensor has detection axes in the orthogonal X and Y directions, and is disposed at the center of the inner circumferential surface of the tire in the tire width direction, with the Y direction of the strain sensor aligned with the tire width direction and the X direction of the strain sensor aligned with the tire rotation direction, and outputs the positive level peak value of the sensor signal waveform when the tire is in contact with the road surface, and outputs the negative level peak value of the sensor signal waveform at the moment the tire contacts or leaves the road surface. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a physical quantity detection device that can accurately detect a plurality of physical quantities together from a sensor signal waveform including the plurality of physical quantities output from one sensor element. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a configuration diagram showing a vehicle equipped with a physical quantity detection device according to the first embodiment. [Figure 2] FIG. 2 is a configuration diagram showing the physical quantity detection device according to the first embodiment. [Figure 3A] FIG. 3A shows the strain sensor according to the first embodiment and is a diagram illustrating the configuration of the strain sensor. [Figure 3B] FIG. 3B shows the strain sensor according to the first embodiment and is an electrical circuit diagram of the strain sensor. [Figure 3C] FIG. 3C shows the strain sensor according to the first embodiment and is a schematic diagram of an output from the strain sensor. [Figure 4] FIG. 4 is a vertical cross-sectional view in the tire width direction showing the arrangement of strain sensors according to the first embodiment. [Figure 5] FIG. 5 is a longitudinal cross-sectional view in the tire rotation direction showing the arrangement of strain sensors according to the first embodiment. [Figure 6] FIG. 6 is an explanatory diagram showing the waveform of a sensor signal from a strain sensor according to the rotational state of a tire according to the first embodiment. [Figure 7] FIG. 7 is a waveform diagram showing the sensor signal waveform of the strain sensor according to the rotational state of the tire according to the first embodiment. [Figure 8] FIG. 8 is an explanatory diagram showing the waveform of a sensor signal of the strain sensor in one period according to the first embodiment. [Figure 9] FIG. 9 is an explanatory diagram showing the sensitivity of other parameters mixed in the sensor signal waveform of the strain sensor in one period according to the first embodiment. [Figure 10] FIG. 10 is an explanatory diagram showing changes in output of the strain sensor in the initial state of the tire according to the first embodiment. [Figure 11] FIG. 11 is an explanatory diagram showing changes in output of the strain sensor depending on the wear state of the tire according to the first embodiment. [Figure 12A] FIG. 12A is an explanatory diagram showing a change in output of a strain sensor depending on the air pressure of a tire according to the first embodiment, and is a cross section of a tire at an appropriate air pressure. [Figure 12B] FIG. 12B is an explanatory diagram showing the change in output of the strain sensor depending on the air pressure of the tire according to the first embodiment, showing a tire cross section in the case of low air pressure. [Figure 12C] FIG. 12C is an explanatory diagram showing the change in output of the strain sensor depending on the air pressure of the tire according to the first embodiment, showing a cross section of the tire in the case of high air pressure. [Figure 13] FIG. 13 is a flowchart for deriving a first table of parameters mixed in the sensor signal waveform of the strain sensor according to the first embodiment. [Figure 14] FIG. 14 is an explanatory diagram showing a first table of parameters mixed in the sensor signal waveform of the strain sensor according to the first embodiment. [Figure 15] FIG. 15 is an explanatory diagram showing a second table of parameters mixed in the sensor signal waveform of the strain sensor according to the first embodiment. [Figure 16] FIG. 16 is a flowchart for estimating the amount of tire wear and the amount of load from the sensor signal waveform of the strain sensor according to the first embodiment. [Figure 17] FIG. 17 is an explanatory diagram for estimating the amount of tire wear by applying the sensor signal waveform of the strain sensor according to the first embodiment to the first table. [Figure 18] FIG. 18 is an explanatory diagram for estimating the load amount of a tire by applying the sensor signal waveform of the strain sensor according to the first embodiment to the second table. [Figure 19] FIG. 19 is an explanatory diagram showing the wear amount estimation results according to the first embodiment. [Figure 20] FIG. 20 is an explanatory diagram showing a load amount estimation result according to the first embodiment. [Figure 21] FIG. 21 is a configuration diagram showing a physical quantity detection device according to the second embodiment. [Figure 22] FIG. 22 is an explanatory diagram showing an air pressure correlation table of the first table showing the correlation between the peak value of the positive level of the sensor signal waveform of the strain sensor according to the second embodiment and the air pressure. [Figure 23] FIG. 23 is an explanatory diagram showing a speed correlation table of the first table showing the correlation between the peak value of the positive level of the sensor signal waveform of the strain sensor according to the second embodiment and the speed. [Figure 24] FIG. 24 is an explanatory diagram showing a temperature correlation table of the first table showing the correlation between the peak value of the positive level of the sensor signal waveform of the strain sensor according to the second embodiment and the temperature. [Figure 25] FIG. 25 is an explanatory diagram showing a load amount correlation table of the first table showing the correlation between the load amount and the peak value of the positive level of the sensor signal waveform of the strain sensor according to the second embodiment. [Figure 26] FIG. 26 is an explanatory diagram showing a first table including various tables according to the second embodiment. [Figure 27]FIG. 27 is an explanatory diagram showing an air pressure correlation table of a second table showing the correlation between air pressure and peak values ​​of negative levels of the sensor signal waveform of the strain sensor according to the second embodiment. [Figure 28] FIG. 28 is an explanatory diagram showing a speed correlation table of the second table showing the correlation between the speed and the peak value of the negative level of the sensor signal waveform of the strain sensor according to the second embodiment. [Figure 29] FIG. 29 is an explanatory diagram showing a temperature correlation table of the second table showing the correlation between the negative peak value of the sensor signal waveform of the strain sensor according to the second embodiment and the temperature. [Figure 30] FIG. 30 is an explanatory diagram showing a second wear amount correlation table showing the correlation between the peak value of the negative level of the sensor signal waveform of the strain sensor according to the second embodiment and the wear amount. [Figure 31] FIG. 31 is an explanatory diagram showing a second table including various tables according to the second embodiment. [Figure 32] FIG. 32 is a flowchart for estimating the amount of tire wear and the amount of load from the sensor signal waveform of the strain sensor according to the second embodiment. [Figure 33] FIG. 33 is a configuration diagram showing a wear amount processing portion of a physical quantity detection device according to the third embodiment. [Figure 34] FIG. 34 is a detailed configuration diagram showing the warning processing unit according to the third embodiment. [Figure 35] FIG. 35 is an explanatory diagram showing the operational state of the wear warning according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention should not be interpreted as being limited to the following embodiments, and the technical concept of the present invention may be realized by combining other known components. In addition, the same elements in each drawing are designated by the same reference numerals, and redundant explanations will be omitted.

[0013] First Embodiment <Overall vehicle configuration> 1 is a configuration diagram showing a vehicle 100 equipped with a physical quantity detection device 10 according to the first embodiment. As shown in FIG. 1, the vehicle 100 includes four tires 101, one ECU 102, and one reporting unit 103. The vehicle 100 also includes four air pressure sensors 1, four temperature sensors 2, and four strain sensors 3. Note that the vehicle 100 is not limited to a two-wheeled or four-wheeled vehicle that travels on a road surface 20, but may also be an airplane that uses a runway, a railway vehicle that uses tires, or the like.

[0014] The vehicle 100 travels on a road surface 20 by rotating four tires 101. A person rides in the vehicle 100.

[0015] The tire 101 is in contact with the road surface 20 and receives the load of the vehicle 100. The tire 101 rotates. The tire 101 is a rubber member.

[0016] The ECU 102 is a control unit that controls the vehicle 100. The ECU 102 has an arithmetic processing unit, a storage unit, and an input / output port electrically connected to various sensors, an arithmetic processing unit such as a CPU, a storage unit such as a memory, and the reporting unit 103.

[0017] The reporting unit 103 is a monitor of a car navigation system. The display screen of the reporting unit 103 is switched among a car navigation screen, a wear amount report screen, and a load amount report screen by interrupt processing from the ECU 102. The display of the display screen of the reporting unit 103 is controlled based on the control of the ECU 102.

[0018] The air pressure sensor 1 acquires the air pressure of each tire 101 and outputs it to the ECU 102. The temperature sensor 2 acquires the temperature of each tire 101 and outputs it to the ECU 102. The strain sensor 3, which is a sensor element, acquires a sensor signal waveform 15 in each tire 101, which contains a mixture of various physical quantities, and outputs it to the ECU 102.

[0019] <Physical quantity detection device 10> 2 is a configuration diagram showing a physical quantity detection device 10 according to a first embodiment. The physical quantity detection device 10 relates to a safe driving support device for a vehicle 100, and in particular, is intended to prevent tire troubles such as bursting due to overload or the like. The physical quantity detection device 10 is a device that detects a physical quantity acting on a tire 101 mounted on the vehicle 100.

[0020] 2, the physical quantity detection device 10 includes a strain sensor 3, an estimation unit 4, and a reporting unit 103. The physical quantity detection device 10 detects a plurality of different physical quantities based on the output signal waveforms.

[0021] <Strain sensor 3> The strain sensor 3 is a sensor element. The strain sensor 3 is a semiconductor that converts a change in resistance into a strain amount and outputs the converted amount. One strain sensor 3 is disposed in each tire 101. The strain sensor 3 outputs a sensor signal waveform 15 having a reference level 151, a positive level that changes to the positive side of the reference level 151, and a negative level that changes to the negative side of the reference level 151. The strain sensor 3 detects the amount of wear using peaks 152 of the positive level relative to the unchanged reference level 151, and detects the amount of load using peaks 153 of the negative level, thereby realizing detection of both amounts with a single strain sensor 3.

[0022] The strain sensor 3 amplifies small changes in resistance and outputs the amount of strain. Since even resistance values ​​that change with ambient temperature affect the output value of the strain sensor 3, the output value deviates from the original value. Therefore, in order to accurately detect the amount of wear and load, it is necessary to correct the amount of strain that changes with air pressure, speed, temperature, etc. Note that temperature and speed information possessed by each vehicle 100 can be used to determine the temperature and speed without installing new sensors. Air pressure information is obtained from the air pressure sensor 1.

[0023] The strain sensor 3 outputs a sensor signal waveform 15 under conditions of predetermined parameters such as at least air pressure, temperature, and speed acquired by the estimation unit 4.

[0024] <Estimation part 4> The estimation unit 4 performs its functions by executing a program in the ECU 102. The estimation unit 4 receives a sensor signal waveform 15 output by the strain sensor 3. Based on the sensor signal waveform 15 output by the strain sensor 3, the estimation unit 4 estimates the amount of wear, which is a first physical quantity corresponding to a peak value 152 of the positive level, and the amount of load, which is a second physical quantity corresponding to a peak value 153 of the negative level.

[0025] The estimation unit 4 acquires the air pressure of the tire 101 from the air pressure sensor 1. The estimation unit 4 acquires the temperature of the tire 101 from the temperature sensor 2. The estimation unit 4 acquires the speed by subtracting the tire circumference from the output period of the sensor signal waveform 15. The estimation unit 4 may also acquire the speed from a speed sensor or the like. The estimation unit 4 estimates the amount of wear and the amount of load from the sensor signal waveform 15 output by the strain sensor 3 under conditions of the acquired parameters such as air pressure, temperature, speed, load amount, and amount of wear. The estimation unit 4 transmits the estimated amount of wear and load amount to the reporting unit 103.

[0026] Here, the estimation unit 4 has two independent blocks, a wear amount block 41 and a load amount block 42, which respectively estimate the wear amount as the first physical quantity and the load amount as the second physical quantity.

[0027] <Wear Block 41> The wear amount block 41 includes a storage unit 411 , a driving condition constraint unit 412 , and an application unit 413 .

[0028] The storage unit 411 has a first table 5 of first physical quantities corresponding to the peak values ​​152 of the positive level of the sensor signal waveform 15 output by the strain sensor 3.

[0029] The driving condition constraint unit 412 transmits the sensor signal waveform 15 of the strain sensor 3 to the application unit 413 when the conditions correspond to predetermined parameters corresponding to the first table 5, in which the parameters of the mixed signal mixed in the sensor signal waveform 15, namely, air pressure, speed, temperature, and load amount, are constrained to fall within predetermined ranges.

[0030] The fitting unit 413 estimates the amount of wear, which is the first physical quantity, by fitting the peak value 152 of the positive level of the sensor signal waveform 15 output by the strain sensor 3 and transmitted by the driving condition constraint unit 412 to the first table 5 stored in the storage unit 411. The fitting unit 413 transmits the estimated amount of wear to the reporting unit 103.

[0031] <Weight Block 42> The load amount block 42 includes a storage unit 421 , a driving condition constraint unit 422 , and an application unit 423 .

[0032] The storage unit 421 has a second table 6 of second physical quantities corresponding to the peak values ​​153 of the negative level of the sensor signal waveform 15 output by the strain sensor 3.

[0033] The driving condition constraint unit 422 transmits the sensor signal waveform 15 of the strain sensor 3 to the application unit 423 when the conditions correspond to predetermined parameters corresponding to the second table 6, in which the parameters of the mixed signal mixed in the sensor signal waveform 15, namely, air pressure, speed, temperature, and wear amount, are constrained to fall within predetermined ranges.

[0034] The fitting unit 423 estimates the load amount, which is the second physical quantity, by fitting the negative level peak value 153 of the sensor signal waveform 15 output by the strain sensor 3 and transmitted by the driving condition constraint unit 422 to the second table 6 stored in the storage unit 421. The fitting unit 423 transmits the estimated load amount to the reporting unit 103.

[0035] <Details of strain sensor 3> 3A to 3C show the strain sensor 3 according to the first embodiment, where FIG. 3A is a configuration diagram of the strain sensor 3, FIG. 3B is an electrical circuit diagram of the strain sensor 3, and FIG. 3C is a schematic diagram of the output of the strain sensor 3.

[0036] 3A, the strain sensor 3 has a plurality of detection units 31 to 34 arranged in a plurality of rows and a plurality of columns in the orthogonal X and Y directions. Here, the strain sensor 3 has four detection units 31 to 34 arranged in two rows and two columns in the orthogonal X and Y directions.

[0037] The strain sensor 3 uses the piezoresistance effect to measure changes in the resistivity of the piezoresistor as an electrical signal. The strain sensor 3 is made up of a 2.5 mm square silicon chip. The piezoresistor is located in the gauge area in the center of the sensor chip of the strain sensor 3.

[0038] As shown in Figure 3B, a Wheatstone bridge circuit consisting of two detection elements 31 and 32, piezoresistors Rv1, Rv2, Rh1, and Rh2, is configured within the gauge region. The piezoresistors are formed by ion implantation and are adjusted to have uniform initial resistance and piezoresistance coefficients. The detection axes of the strain sensor 3 are the X and Y directions of the chip's edges. The output voltage of the strain sensor 3 changes in proportion to the strain applied to the chip in the X or Y direction. The strain sensor 3 generates the same strain in both the X and Y directions. The strain sensor 3 does not generate an output for simple shear strain or isotropic strain. When the strains in the X and Y directions are different, the strain sensor 3 generates an output proportional to the difference between the two (Vp - Vn). The piezoresistors change their output polarity depending on the direction of strain in the XY plane.

[0039] As shown in Figure 3C, for example, if the plane is warped so that the sensor surface expands in the X direction, the resistance of Rh2 and Rh1 increases, so the Vp output increases and the Vn output decreases, resulting in a positive Vp-Vn output. Conversely, if the plane is warped so that the sensor surface compresses in the X direction, the resistance of Rh2 and Rh1 decreases, so the Vp output decreases and the Vn output increases, resulting in a negative Vp-Vn output.

[0040] Fig. 4 is a longitudinal cross-sectional view in the tire width direction showing the arrangement of the strain sensor 3 according to the first embodiment. As shown in Fig. 4, the strain sensor 3 is arranged in the center in the tire width direction on the inner circumferential side of the tire 101. The strain sensor 3 is arranged in the tire 101 such that the Y direction, in which the two detectors 31, 32 and the two detectors 33, 34 are aligned and output, is aligned along the tire 101 width direction.

[0041] 5 is a longitudinal cross-sectional view in the tire rotation direction showing the arrangement of the strain sensor 3 according to the first embodiment. As shown in Fig. 5, the strain sensor 3 is arranged on the tire 101 with the X direction in which the two detectors 31 and 33 and the two detectors 32 and 34 are aligned and output, respectively, aligned along the rotation direction.

[0042] <Sensor signal waveform 15> 6 is an explanatory diagram showing a sensor signal waveform 15 of the strain sensor 3 according to the rotation state of the tire 101 according to the first embodiment. As shown in FIG. 6, the strain sensor 3 disposed inside the tire 101 outputs a sensor signal waveform 15 that changes depending on the state of the rotating tire 101.

[0043] The strain sensor 3 outputs a sensor signal waveform 15 having a reference level 151, a positive level that changes to the positive side of the reference level 151, and a negative level that changes to the negative side of the reference level 151.

[0044] The strain sensor 3 maintains the reference level 151 of the sensor signal waveform 15 when not in contact with the ground. The strain sensor 3 outputs a positive level peak value 152 of the sensor signal waveform 15 when the tire 101 is in contact with the road surface 20. The strain sensor 3 outputs a negative level peak value 153 of the sensor signal waveform 15 at the moment when the tire 101 touches or leaves the road surface 20. Here, the moment when the tire 101 touches or leaves the road surface 20 is a sensor displacement point. The period between two sensor displacement points is a contact period when the tire 101 is in contact with the road surface 20.

[0045] The sensor signal waveform 15 thus detected varies depending on various physical quantities (amount of wear, amount of load, air pressure, speed, temperature).

[0046] FIG. 7 is a waveform diagram showing the sensor signal waveform 15 of the strain sensor 3 according to the rotation state of the tire 101 according to the first embodiment. As shown in FIG. 7, as the tire 101 rotates, the sensor signal waveform 15 of the strain sensor 3 alternates between a reference level 151, a negative level that changes to a negative side relative to the reference level 151, a positive level that changes to a positive side relative to the reference level 151, and a negative level that changes to a negative side relative to the reference level 151. The signal value of the sensor signal waveform 15 can be expressed by signal amplitude. In FIGS. 6 to 7, the sensor signal waveform 15 is also expressed by amplitude. The signal amplitude here may be any value that represents the amplitude of the sensor signal waveform 15. The sensor signal waveform 15 has a waveform in which a falling waveform is successively formed before and after a rising waveform, as shown in FIG. 8. For example, the amplitude of the second falling waveform can be treated as the amplitude of the sensor signal waveform 15. This is assumed below.

[0047] Fig. 8 is an explanatory diagram showing a sensor signal waveform 15 of the strain sensor 3 in one cycle according to the first embodiment. Fig. 8 is an enlarged view of part A in Fig. 7. As shown in Fig. 8, the amount of wear, which is a first physical quantity, is detected at a peak value 152 of the positive level. The amount of load, which is a second physical quantity, is detected at a peak value 153 of the negative level.

[0048] FIG. 9 is an explanatory diagram showing the sensitivity of other parameters mixed in the sensor signal waveform 15 of the strain sensor 3 in one cycle according to the first embodiment. The sensor signal waveform 15 shown in FIG. 8 is advantageous for detecting the amount of wear and the amount of load. However, as shown in FIG. 9, when the sensor signal waveform 15 output by changing the driving conditions is examined, the positive-level peak value 152 and the negative-level peak value 153 are sensitive to the air pressure, temperature, speed, amount of wear, and amount of load. In other words, the signals of the air pressure, temperature, speed, amount of wear, and amount of load are mixed in the positive-level peak value 152 and the negative-level peak value 153.

[0049] It should be noted that the reference level 151 is insensitive to air pressure, temperature, speed, wear, and load. In other words, the reference level 151 does not include signals of air pressure, temperature, speed, wear, and load.

[0050] <Change in Output of Strain Sensor 3 in Initial State or Worn State of Tire 101> 10 is an explanatory diagram showing the change in output of the strain sensor 3 in the initial state of the tire 101 according to the first embodiment. As shown in Fig. 10, the strain sensor 3 is pulled into an upward convex shape in accordance with the plane of the inner periphery of the tire 101, which follows the initial state of the tire 101 in contact with the road surface 20. As a result, the output of the strain sensor 3 increases in the negative direction.

[0051] The sensor signal waveform 15 is affected by the output of the strain sensor 3, which has increased in the negative direction, so that the peak value 152 at the positive level decreases, and the peak value 153 at the negative level increases.

[0052] 11 is an explanatory diagram showing the change in output of the strain sensor 3 as the tire 101 according to the first embodiment wears. As shown in Fig. 11, the strain sensor 3 is pulled into an upward convex shape that is smaller than that of the initial tire 101, in accordance with the downward concave surface of the inner circumference of the tire 101 that imitates the worn tire 101 in contact with the road surface 20. As a result, the output of the strain sensor 3 decreases in the negative direction.

[0053] The sensor signal waveform 15 is affected by the output of the strain sensor 3, which has decreased in the negative direction, and the peak value 152 of the positive level increases, while the peak value 153 of the negative level decreases.

[0054] <Changes in strain sensor 3 output due to air pressure> Figures 12A to 12C are explanatory diagrams showing the change in output of the strain sensor 3 depending on the air pressure of the tire 101 in the first embodiment, where Figure 12A is a cross section of the tire 101 at the appropriate air pressure, Figure 12B is a cross section of the tire 101 at the low air pressure, and Figure 12C is a cross section of the tire 101 at the high air pressure.

[0055] Fig. 12A shows a cross section of a tire 101 with a proper air pressure. As shown in Fig. 12A, in a tire 101 with a proper air pressure, the output of the strain sensor 3 is less affected by being pulled in the vertical direction. As a result, the output of the strain sensor 3 is less likely to trend in the positive or negative direction.

[0056] The sensor signal waveform 15 is not affected by the output of the strain sensor 3, which is now less likely to move in the positive or negative direction, and the peak value 152 of the positive level and the peak value 153 of the negative level do not become larger or smaller.

[0057] 12B shows a cross section of a tire 101 with low inflation pressure. As shown in Fig. 12B, in a tire 101 with low inflation pressure, the output of the strain sensor 3 is pulled in an upward convex shape along the upward convex surface of the inner circumference of the tire 101. As a result, the output of the strain sensor 3 increases in the negative direction.

[0058] The sensor signal waveform 15 is affected by the output of the strain sensor 3, which has increased in the negative direction, so that the peak value 152 at the positive level decreases, and the peak value 153 at the negative level increases.

[0059] The phenomenon of the tire 101 in the case of low air pressure also occurs when the temperature of the tire 101 is low, when the speed of the tire 101 is low, or when the load on the tire 101 is small.

[0060] 12C shows a cross section of tire 101 when the tire is highly inflated. As shown in Fig. 12C, in tire 101 when the tire is highly inflated, the output of strain sensor 3 is pulled downward in a concave shape along the downward concave surface of the inner circumference of tire 101. As a result, the output of strain sensor 3 increases in the positive direction.

[0061] The sensor signal waveform 15 is affected by the output of the strain sensor 3, which has increased in the positive direction, and the peak value 152 of the positive level increases, while the peak value 153 of the negative level decreases.

[0062] The phenomenon of the tire 101 in the case of high air pressure also occurs when the temperature of the tire 101 is high, when the speed of the tire 101 is high, or when the load is large.

[0063] 12A to 12C, it is clear that it is necessary to correct for the temperature, speed, and other components of the wear amount and load amount that cause mixed air pressure and similar phenomena when extracting the wear amount and load amount from the sensor signal waveform 15. However, in this embodiment, the air pressure, temperature, speed, load amount, or wear amount is not varied, and the physical quantity detection device 10 detects the wear amount and load amount under predetermined driving conditions.

[0064] In other words, the physical quantity detection device 10 causes the strain sensor 3 to output the sensor signal waveform 15 under conditions of predetermined parameters corresponding to the first table 5 and the second table 6, where at least the air pressure, speed, and temperature, which are parameters of the mixed signal mixed in the sensor signal waveform 15, are constrained to fall within predetermined ranges.

[0065] <How to create Table 15> FIG. 13 is a flowchart for deriving the first table 5 of parameters mixed in the sensor signal waveform 15 of the strain sensor 3 according to the first embodiment.

[0066] As shown in FIG. 13, in S101, a predetermined control unit for the table creation test runs the vehicle 100 while maintaining the standard air pressure, temperature, speed, and load amount, and acquires the output of the strain sensor 3 in response to changes in the amount of wear.

[0067] In S102, the control unit acquires a relationship representing the change from the reference waveform for the sensor signal waveform 15 of the strain sensor 3 when the amount of wear changes relative to the reference amount of wear when the vehicle 100 is driven while maintaining the reference air pressure, temperature, speed, and load amount.

[0068] In S103, the control unit stores in the first table 5 the change from the reference waveform of the sensor signal waveform 15 acquired in S102.

[0069] The change in sensor signal waveform 15 when the amount of wear changes does not necessarily have to be expressed using the difference from the reference amount of wear and the difference from the reference signal value. However, because the absolute value of the signal value differs for each vehicle model and tire type, it becomes necessary to create data similar to first table 5 for each absolute value in advance, which would significantly increase the amount of data. Therefore, by describing the data using the difference from the reference value, the amount of data is reduced.

[0070] Furthermore, the second table 6 can be derived by running the vehicle 100 under the conditions of running the vehicle 100 fixed to the standard air pressure, temperature, speed and amount of wear in the above flow chart.

[0071] FIG. 14 is an explanatory diagram showing a first table 5 of parameters mixed in the sensor signal waveform 15 of the strain sensor 3 according to the first embodiment. As shown in FIG. 14, the first table 5 is a proportional graph of correlation with the sensor signal waveform 15, in which a small positive correction amount is obtained when the amount of wear is small and a large positive correction amount is obtained when the amount of wear is large. The first table 5 is stored in the memory unit 411. The first table 5 is derived by subtracting the correction amounts of various physical quantities, including the air pressure correction, speed correction, temperature correction, and load amount correction lines, from the line of the peak value 152 at the positive level of the apparent sensor signal waveform 15.

[0072] Here, the change in the sensor signal waveform 15 in response to a change in the amount of wear is illustrated. The estimation unit 4 acquires the relationship between the amount of wear acting on the tire 101 and the sensor signal waveform 15 at that time under reference air pressure, speed, temperature, and load amount. For example, a relationship like that shown in FIG. 14 is acquired for each combination of the vehicle model and tire type of the vehicle 100. These relationships may be acquired by actual measurement or by other means such as an appropriate simulation. Here, the reference wear is set to 7.2 mm (equivalent to the tread depth of a new tire), the reference load is 340 kg (equivalent to two occupants), the reference air pressure is 220 kPa, and the reference temperature is 30°C. The reference speed can be set to, for example, 7 km / h. Similar relationships may also be acquired for speeds other than the reference speed.

[0073] FIG. 15 is an explanatory diagram showing a second table 6 of parameters mixed in the sensor signal waveform 15 of the strain sensor 3 according to the first embodiment. As shown in FIG. 15, the second table 6 is a proportional correlation graph in which the negative correction amount is small when the load amount is small and the negative correction amount is large when the load amount is large. The second table 6 is stored in the memory unit 421. The second table 6 is derived by subtracting the correction amounts of various physical quantities, including air pressure correction, speed correction, temperature correction, and wear amount correction, from the line of the negative peak value 153 of the apparent sensor signal waveform 15, to obtain the line of the actual amount of wear that is being calculated.

[0074] In the second table 6, the same running conditions as those in the first table 6 are set as for the standard air pressure, speed, temperature and wear amount.

[0075] <Physical quantity detection method> Fig. 16 is a flowchart for estimating the amount of wear and load on a tire 101 from a sensor signal waveform 15 of a strain sensor 3 according to the first embodiment. Fig. 17 is an explanatory diagram for estimating the amount of wear on a tire 101 by applying a sensor signal waveform 15 of a strain sensor 3 according to the first embodiment to a first table 5. Fig. 18 is an explanatory diagram for estimating the amount of load on a tire 101 by applying a sensor signal waveform 15 of a strain sensor 3 according to the first embodiment to a second table 6.

[0076] The flowchart of the physical quantity detection method shown in FIG. 16 is repeatedly executed while the vehicle 100 is traveling.

[0077] When the physical quantity detection method is performed, in S201, the estimation unit 4 determines whether or not the driving condition constraints set by the driving condition constraint units 412, 422 are satisfied in the driving state of the vehicle 100. Driving condition constraints are conditions that match the driving conditions when the first table 5 and the second table 6 are derived. If the driving condition constraints set by the driving condition constraint units 412, 422 are satisfied in S201, the processing proceeds to S202. If the driving condition constraints set by the driving condition constraint units 412, 422 are not satisfied in S201, the processing of the physical quantity detection method is temporarily terminated.

[0078] In S202, the estimation unit 4 detects the peak value 152 of the positive level of the sensor signal waveform 15 output by the strain sensor 3. After the process of S202, the process proceeds to S203.

[0079] In S203, the estimation unit 4 detects the peak value 153 of the negative level of the sensor signal waveform 15 output by the strain sensor 3. After the process of S203, the process proceeds to S204.

[0080] In S204, as shown in Fig. 17, the estimation unit 4 applies the peak value 152 of the positive level of the sensor signal waveform 15 output by the strain sensor 3 detected in S202 to the first table 5 stored in the storage unit 411. In this way, the estimation unit 4 estimates the amount of wear, which is the first physical quantity. The estimated amount of wear is transmitted to the reporting unit 103. After the processing of S204, the processing proceeds to S205.

[0081] 18, in S205, the estimation unit 4 applies the negative level peak value 153 of the sensor signal waveform 15 output by the strain sensor 3 detected in S203 to the second table 6 stored in the storage unit 421. In this way, the estimation unit 4 estimates the load amount, which is the second physical quantity. The estimated load amount is transmitted to the reporting unit 103. After the processing of S205, the processing of the physical quantity detection method is temporarily terminated.

[0082] <Wear volume estimation results> Fig. 19 is an explanatory diagram showing the results of wear amount estimation according to the first embodiment. As shown in Fig. 19, the results of calculations using actual vehicle data under conditions of air pressure 220 kPa, speed 2.4 m / s (approximately 9 km / h), 30°C, and two occupants showed an accuracy of 5.4 mm for a tire groove depth of 5 mm, which is almost good, and it was confirmed that the wear estimation error was 10% or less.

[0083] <Load amount estimation results> Fig. 20 is an explanatory diagram showing the load amount estimation results according to the first embodiment. As shown in Fig. 20, the calculation results using actual vehicle data under the conditions of a speed of 2.4 m / s (approximately 9 km / h), temperature of 30°C, two occupants, and a tire groove depth of 5 mm showed a tendency for good accuracy at the lower air pressure to indicate a load of 313 kg for an actually measured load of 340 kg, and it was confirmed that the load estimation error was 10% or less.

[0084] Second Embodiment The following describes an embodiment that is a modification of the above embodiment. In the following, the same components as those in the first embodiment are denoted by the same reference numerals and the description of the characteristic parts is omitted.

[0085] Fig. 21 is a configuration diagram showing a physical quantity detection device 10 according to a second embodiment. As shown in Fig. 21, in the second embodiment, the estimation unit 4 does not have a driving condition constraint unit, and estimates the amount of wear and the amount of load even if the air pressure, temperature, speed, amount of load, and amount of wear are variable values.

[0086] The correlation between the peak value 152 of the positive level of the sensor signal waveform 15 of the strain sensor 3 and the air pressure, temperature, speed, and load amount was stored in advance by varying these values.

[0087] 22 is an explanatory diagram showing a first air pressure correlation table indicating the correlation between the air pressure and the correction amount for the peak value of the positive level of the sensor signal waveform 15 of the strain sensor 3 according to the second embodiment. The table shown in FIG. 22 shows a correlation in which the correction amount for the peak value 152 of the positive level of the sensor signal waveform 15 decreases as the air pressure increases.

[0088] 23 is an explanatory diagram showing a temperature correlation table of the first table 5 indicating the correlation between the speed and the amount of correction for the peak value 152 at the positive level of the sensor signal waveform 15 of the strain sensor 3 according to the second embodiment. The table shown in FIG. 23 obtains a correlation in which the amount of correction for the peak value 152 at the positive level of the sensor signal waveform 15 increases as the speed increases.

[0089] 24 is an explanatory diagram showing a temperature correlation table of the first table 5 indicating the correlation between the temperature and the amount of correction for the peak value 152 at the positive level of the sensor signal waveform 15 of the strain sensor 3 according to the second embodiment. The table shown in FIG. 24 shows a correlation in which the amount of correction for the peak value 152 at the positive level of the sensor signal waveform 15 increases as the temperature increases.

[0090] 25 is an explanatory diagram showing a load amount correlation table of the first table 5 indicating the correlation between the load amount and the correction amount of the peak value 152 at the positive level of the sensor signal waveform 15 of the strain sensor 3 according to the second embodiment. The table shown in Fig. 25 acquires a correlation in which the correction amount of the peak value 152 at the positive level of the sensor signal waveform 15 increases as the load amount increases.

[0091] Fig. 26 is an explanatory diagram showing the first table 5 that includes various tables according to the second embodiment. As shown in Fig. 26, the first table 5 includes the reference first table of the first embodiment and the various correlation tables of Figs. 21 to 25. Therefore, by applying the peak value 152 of the positive level of the sensor signal waveform 15 output by the strain sensor 3 in the vehicle 100 while it is traveling in various ways to the first table 5 stored in the storage unit 411, it is possible to estimate the amount of wear, which is the first physical quantity.

[0092] Specifically, the air pressure, speed, temperature, and load amount are applied to various correlation tables, respectively, to derive a correction amount for the peak value 152 at the positive level of the sensor signal waveform 15. The peak value 152 at the positive level of the sensor signal waveform 15 is then applied to the reference first table. At this time, the derived correction amount is applied to the correction amount on the reference first table. This allows the amount of wear, which is the first physical quantity, to be estimated.

[0093] The correlations between the minus level peak value 153 of the sensor signal waveform 15 of the strain sensor 3 and the air pressure, temperature, speed and wear amount were stored in advance by varying these values.

[0094] 27 is an explanatory diagram showing the air pressure correlation table of the second table 6, which shows the correlation between the air pressure and the correction amount of the peak value 153 at the negative level of the sensor signal waveform 15 of the strain sensor 3 according to the second embodiment. The table shown in Fig. 27 shows the correlation in which the correction amount of the peak value 153 at the negative level of the sensor signal waveform 15 decreases as the air pressure increases.

[0095] 28 is an explanatory diagram showing the speed correlation table of the second table 6, which shows the correlation between the speed and the amount of correction for the peak value 153 at the negative level of the sensor signal waveform 15 of the strain sensor 3 according to the second embodiment. The table shown in Fig. 28 shows a correlation in which the amount of correction for the peak value 153 at the negative level of the sensor signal waveform 15 increases as the speed increases.

[0096] 29 is an explanatory diagram showing a temperature correlation table of the second table 6 indicating the correlation between the temperature and the correction amount of the peak value 153 at the negative level of the sensor signal waveform 15 of the strain sensor 3 according to the second embodiment. The table shown in FIG. 29 shows a correlation in which the correction amount of the peak value 153 at the negative level of the sensor signal waveform 15 increases as the temperature increases.

[0097] 30 is an explanatory diagram showing a wear amount correlation table of the second table 6, which shows the correlation between the amount of wear and the correction amount of the peak value 153 at the negative level of the sensor signal waveform 15 of the strain sensor 3 according to the second embodiment. The table shown in Fig. 30 shows a correlation in which the amount of wear increases as the amount of wear increases.

[0098] Fig. 31 is an explanatory diagram showing second table 6, which includes various tables according to the second embodiment and the reference second table of the first embodiment. As shown in Fig. 31, second table 6 includes the reference second table and the various correlation tables of Figs. 27 to 30. Therefore, by applying negative level peak value 153 of sensor signal waveform 15 output by strain sensor 3 in various traveling vehicle 100 to second table 6 stored in storage unit 421, it is possible to estimate the load amount, which is the second physical quantity.

[0099] Specifically, the air pressure, speed, temperature, and wear amount are applied to various correlation tables, respectively, to derive a correction amount for the negative level peak value 153 of the sensor signal waveform 15. Then, the negative level peak value 153 of the sensor signal waveform 15 is applied to the reference second table. At this time, the derived correction amount is applied to the correction amount on the reference second table. This allows the load amount, which is the second physical quantity, to be estimated.

[0100] <Physical quantity detection method> FIG. 32 is a flowchart for estimating the amount of wear and the amount of load on the tire 101 from the sensor signal waveform 15 of the strain sensor 3 according to the second embodiment.

[0101] 32 is repeatedly executed while the vehicle 100 is traveling. In the second embodiment, the process of S201 in the first embodiment is not performed.

[0102] When the physical quantity detection method is performed, in S202, the estimation unit 4 detects the peak value 152 of the positive level of the sensor signal waveform 15 output by the strain sensor 3. After the process of S202, the process proceeds to S203.

[0103] In S203, the estimation unit 4 detects the peak value 153 of the negative level of the sensor signal waveform 15 output by the strain sensor 3. After the process of S203, the process proceeds to S204a.

[0104] In S204a, the estimation unit 4 applies the peak value 152 of the positive level of the sensor signal waveform 15 output by the strain sensor 3 detected in S202 to the first table 5 stored in the storage unit 411. In this way, the estimation unit 4 estimates the amount of wear, which is the first physical quantity. The estimated amount of wear is transmitted to the reporting unit 103. After the processing of S204, the processing proceeds to S205a.

[0105] Here, various tables for varying air pressure, speed, temperature, and load are stored in the first table 5. Therefore, the amount of wear can be estimated without restricting the running conditions.

[0106] In S205a, the estimation unit 4 applies the negative level peak value 153 of the sensor signal waveform 15 output by the strain sensor 3 detected in S203 to the second table 6 stored in the storage unit 421. In this way, the estimation unit 4 estimates the load amount, which is the second physical quantity. The estimated load amount is transmitted to the reporting unit 203. After the processing of S205a, the processing of the physical quantity detection method is temporarily terminated.

[0107] Here, various tables for varying air pressure, speed, temperature, and wear amount are stored in the second table 6. Therefore, it is possible to estimate the load amount without restricting the running conditions.

[0108] <Third embodiment> In the third embodiment, a reporting unit 103 is provided that classifies the range of the wear amount, which is the first physical quantity, or the load amount, which is the second physical quantity, into multiple stages and issues a warning about the state of each stage. Here, the reporting unit 103 issues a warning about the wear amount.

[0109] Fig. 33 is a configuration diagram showing a wear amount estimation portion of the physical quantity detection device 10 according to the third embodiment. Fig. 34 is a detailed configuration diagram showing a warning processing unit 43 according to the third embodiment.

[0110] As shown in FIGS. 33 and 34 , the physical quantity detection device 10 further includes a warning processing unit 43 that warns of the amount of wear. The warning processing unit 43 includes a groove depth classification determination unit 431, a count-up processing unit 432, and a groove depth determination unit 433. The groove depth classification determination unit 431 divides groove depths into four groups. The count-up processing unit 432 counts the number of data points for each groove depth to obtain a distribution of groove depths. The groove depth determination unit 433 determines the groove depth with the largest number of data points by tallying the number of data points for each groove depth, and outputs 1 mm, 3 mm, 5 mm, or 7 mm to the reporting unit 103 depending on the groove depth at that time. As a result, the warning processing unit 43 classifies the range of the amount of wear into multiple stages and warns the reporting unit 103 of the status of each stage.

[0111] FIG. 35 is an explanatory diagram showing the operation state of a wear warning according to the third embodiment. As shown in FIG. 35, when a tire 101 is new, wear is not advanced, so it is considered that there is little need to detect the amount of wear, and a system for notifying the amount of wear in real time is not required. Therefore, in the third embodiment, the physical quantity detection device 10 is configured to notify the amount of wear by issuing a warning when the tread depth decreases. That is, tread depth is divided into four groups, for example, A "1 to 2 mm," B "2 to 4 mm," C "4 to 6 mm," and D "6 mm or more." A method of tallying data for each group is set on a monthly basis. For example, when the tread depth corresponds to C "4 to 6 mm," a green warning (an alarm indicating that tire replacement is not necessary) is issued by the reporting unit 103. When the tread depth corresponds to B "2 to 4 mm," a yellow warning (an alarm indicating that tire replacement is imminent) is issued by the reporting unit 103. When the tread depth corresponds to A "1 to 2 mm," a red warning (an alarm indicating that tire replacement is necessary) is issued by the reporting unit 103.

[0112] For example, if the groove depth for each month is 1.6 mm, the warning processing unit 43 determines that it falls into groove depth group A "1 to 2 mm," and the groove depth determination unit 433 selects a groove depth output of "1 mm." Then, the reporting unit 104 displays a red warning.

[0113] In this way, by installing the warning processing unit 43 in the physical quantity detection device 10, the amount of wear can be detected with high accuracy and the groove depth can be determined correctly, so that the timing of tire replacement can be correctly notified by the warning display.

[0114] <Effects> (A) A physical quantity detection device 10 detects a plurality of different physical quantities based on an output signal waveform. The physical quantity detection device 10 includes a strain sensor 3, which is a single sensor element, that outputs a sensor signal waveform 15 having a reference level 151, a positive level that changes more positively than the reference level 151, and a negative level that changes more negatively than the reference level 151. The physical quantity detection device 10 also includes an estimation unit 4 that estimates, based on the sensor signal waveform 15 output by the strain sensor 3, a first physical quantity corresponding to a peak value 152 of the positive level and a second physical quantity corresponding to a peak value 153 of the negative level.

[0115] In this configuration, at least two detection values ​​are distinguished from one peak 152 and the other peak 153 of the positive and negative levels with respect to a reference level 151 of a sensor signal waveform 15 output from one strain sensor 3. This allows multiple physical quantities to be detected together based on the two detection values ​​of one strain sensor 3. Therefore, multiple physical quantities are detected together with high accuracy from a sensor signal waveform 15 including multiple physical quantities output from one strain sensor 3.

[0116] (B) The estimation unit 4 has a storage unit 411 that stores a first table 5 of first physical quantities corresponding to peak values ​​152 of the positive level of the sensor signal waveform 15. The estimation unit 4 has a storage unit 421 that stores a second table 6 of second physical quantities corresponding to peak values ​​153 of the negative level of the sensor signal waveform 15. The estimation unit 4 estimates the first physical quantity by applying peak values ​​152 of the positive level of the sensor signal waveform 15 output by the strain sensor 3 to the first table 5 stored in the storage unit 411. The estimation unit 4 estimates the second physical quantity by applying peak values ​​153 of the negative level of the sensor signal waveform 15 output by the strain sensor 3 to the second table 6 stored in the storage unit 421.

[0117] In this configuration, the sensor signal waveform 15 including multiple physical quantities output by one strain sensor 3 is applied to the first table 5 and the second table 6 in the memory units 411 and 421, respectively, and the first physical quantity and the second physical quantity to be detected are detected together with high accuracy.

[0118] (C) The sensor element is a strain sensor 3.

[0119] In this configuration, the sensor element is a strain sensor 3. As a result, even if the sensor signal waveform 15 contains components due to mixed physical quantities, the detected strain is unlikely to be affected under certain parameter conditions. Therefore, the detection accuracy of the strain of the multiple physical quantities to be detected is improved.

[0120] (D) The estimation unit 4 performs temperature correction on the peak value 152 of the positive level and the peak value 153 of the negative level of the sensor signal waveform 15 output by the strain sensor 3 .

[0121] In this configuration, even if the sensor signal waveform 15 contains components caused by temperature, both peak values ​​152 and 153 are temperature-corrected, thereby improving the detection accuracy of the multiple physical quantities to be detected.

[0122] (E) The estimation unit has two independent blocks, a wear amount block 41 and a load amount block 42, which estimate the first physical quantity and the second physical quantity, respectively.

[0123] In this configuration, two independent blocks, a wear amount block 41 and a load amount block 42, estimate the first physical quantity and the second physical quantity, respectively, thereby improving the calculation speed and detection accuracy of the first physical quantity and the second physical quantity to be detected.

[0124] (F) The strain sensor 3 is disposed on the tire 101. The strain sensor 3 outputs a peak value 152 of the positive level of the sensor signal waveform 15 when the tire 101 is in contact with the road surface 20. The strain sensor 3 outputs a peak value 153 of the negative level of the sensor signal waveform 15 at the moment when the tire 101 contacts or separates from the road surface 20.

[0125] In this configuration, the first physical quantity and the second physical quantity are detected together in time series with high accuracy from the sensor signal waveform 15 including a plurality of physical quantities output from one strain sensor 3 arranged on the tire 101.

[0126] (G) The first physical quantity is the amount of wear, and the second physical quantity is the amount of load.

[0127] In this configuration, the amount of wear and the amount of load are detected together with high accuracy from the sensor signal waveform 15 that includes a plurality of physical quantities output from one strain sensor 3.

[0128] (H) The physical quantity detection device 10 causes the strain sensor 3 to output a sensor signal waveform 15 under the conditions of predetermined parameters corresponding to the first table 5 and the second table 6.

[0129] In this configuration, a certain correction process can be performed by restricting the conditions of the parameters of the components mixed in the sensor signal waveform 15 output from one strain sensor 3. This allows multiple physical quantities to be detected together with high accuracy based on the sensor signal waveform 15.

[0130] (I) The physical quantity detection device 10 causes the strain sensor 3 to output the sensor signal waveform 15 under conditions of predetermined parameters corresponding to the first table 5 and the second table 6, where at least the air pressure, speed, and temperature, which are parameters of the mixed signal mixed in the sensor signal waveform 15, are constrained to fall within predetermined ranges.

[0131] In this configuration, only a certain correction process can be performed by restricting the conditions of the parameters of air pressure, speed, and load amount among the components mixed in the sensor signal waveform 15 output by one strain sensor 3. This allows multiple physical quantities to be detected together with high accuracy based on the sensor signal waveform 15.

[0132] (J) The strain sensor 3 is disposed on the tire 101. The estimation unit 4 acquires the temperature of the tire 101.

[0133] In this configuration, even if the sensor signal waveform 15 contains components caused by temperature, both peak values ​​152 and 153 are temperature-corrected, thereby improving the detection accuracy of the multiple physical quantities to be detected.

[0134] (K) The strain sensor 3 is disposed on the tire 101. The estimation unit 4 obtains the speed by subtracting the tire circumference from the output period of the sensor signal waveform 15.

[0135] In this configuration, even if the sensor signal waveform 15 contains components due to mixed speeds, both peak values ​​152 and 153 are speed-corrected, thereby improving the detection accuracy of the multiple physical quantities to be detected.

[0136] (L) The strain sensor 3 is disposed on the tire 101. The estimation unit 4 acquires the air pressure of the tire 101.

[0137] In this configuration, even if the sensor signal waveform 15 includes components due to mixed air pressure, both peak values ​​152 and 153 are corrected for air pressure, thereby improving the detection accuracy of the multiple physical quantities to be detected.

[0138] (M) The physical quantity detection device 10 includes a warning processing unit 43 that distinguishes the range of the first physical quantity or the second physical quantity into a plurality of stages and issues a warning about the state in each stage.

[0139] In this configuration, the warning processing unit 43 warns the user of the state of the first physical quantity or the second physical quantity at each of the multiple stages that are distinguished from one another in the range of the first physical quantity or the second physical quantity, thereby enabling the user to grasp the state of the first physical quantity or the second physical quantity at each stage through the reporting unit 103.

[0140] (N) The strain sensor 3 is disposed on the inner circumferential side of the tire 101 at the center in the tire width direction.

[0141] In this configuration, the sensor signal waveform 15 output from one strain sensor 3 is detected in a balanced manner in accordance with the deformation of the tire 101 on both sides of the strain sensor 3 in the tire width direction, thereby improving the detection accuracy of multiple physical quantities to be detected.

[0142] (O) One sensor element is a strain sensor 3 having a plurality of detection units 31-34 arranged in a plurality of rows and a plurality of columns in the orthogonal X and Y directions. The strain sensor 3 is arranged on the tire 101 so that either the X direction or the Y direction, in which at least two detection units 31-34 are lined up and output, is aligned with the tire rotation direction.

[0143] In this configuration, since the sensor element is the strain sensor 3, distortion is detected as an output of a positive or negative level according to the deformation caused by the rotation of the tire 101. This improves the detection accuracy of the distortion of the multiple physical quantities to be detected.

[0144] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments. [Explanation of symbols]

[0145] 1...air pressure sensor, 2...temperature sensor, 3...strain sensor, 4...estimation unit, 5...first table, 6...second table, 10...physical quantity detection device, 15...sensor signal waveform, 20...road surface, 41...wear amount block, 42...load amount block, 43...warning processing unit, 100...vehicle, 101...tire, 102...ECU, 103...reporting unit, 151...reference level, 152...positive level peak value, 153...negative level peak value, 411...memory unit, 412...driving condition constraint unit, 413...application unit, 421...memory unit, 422...driving condition constraint unit, 423...application unit, 431...tread depth classification determination unit, 432...count-up processing unit, 433...tread depth determination unit.

Claims

1. A physical quantity detection device that detects a plurality of different physical quantities based on an output signal waveform, a strain sensor that outputs a sensor signal waveform having a reference level, a positive level that changes to a positive side of the reference level, and a negative level that changes to a negative side of the reference level; an estimation unit that estimates, based on the sensor signal waveform output by the strain sensor, an amount of tire wear of the vehicle corresponding to the peak value of the positive level and an amount of load acting on the tire corresponding to the peak value of the negative level; Equipped with The strain sensor is The orthogonal X and Y directions are detection axes, the strain sensor is disposed at the center in the tire width direction of the inner circumferential surface of the tire, with the Y direction of the strain sensor aligned with the tire width direction and the X direction of the strain sensor aligned with the tire rotation direction; outputting the peak value of the positive level of the sensor signal waveform when the tire is in contact with the road surface; The peak value of the negative level of the sensor signal waveform is output at the moment when the tire contacts or separates from the road surface. Physical quantity detection device.

2. The physical quantity detection device according to claim 1 , The estimation unit a storage unit that stores a first table of the wear amount corresponding to the peak value of the positive level of the sensor signal waveform, and a second table of the load amount corresponding to the peak value of the negative level of the sensor signal waveform, the wear amount is estimated by applying the peak value of the positive level of the sensor signal waveform output by the strain sensor to the first table stored in the storage unit; The load amount is estimated by applying the negative level peak value of the sensor signal waveform output by the strain sensor to the second table stored in the storage unit. Physical quantity detection device.

3. The physical quantity detection device according to claim 1 , The estimation unit performs temperature compensation on the peak value of the positive level and the peak value of the negative level of the sensor signal waveform output by the strain sensor. Physical quantity detection device.

4. The physical quantity detection device according to claim 1 , The estimation unit has two independent blocks for estimating the wear amount and the load amount, respectively. Physical quantity detection device.

5. The physical quantity detection device according to claim 2, The physical quantity detection device causes the strain sensor to output the sensor signal waveform under conditions of predetermined parameters corresponding to the first table and the second table. Physical quantity detection device.

6. The physical quantity detection device according to claim 2, The physical quantity detection device causes the strain sensor to output the sensor signal waveform under conditions of predetermined parameters corresponding to the first table and the second table, where at least air pressure, speed, and temperature, which are parameters of a mixed signal mixed in the sensor signal waveform, are restricted to predetermined ranges. Physical quantity detection device.

7. The physical quantity detection device according to claim 1 , The estimation unit acquires the temperature of the tire. Physical quantity detection device.

8. The physical quantity detection device according to claim 1 , The estimation unit obtains the speed by subtracting the tire circumference from the output period of the sensor signal waveform. Physical quantity detection device.

9. The physical quantity detection device according to claim 1 , The estimation unit acquires the tire air pressure. Physical quantity detection device.

10. The physical quantity detection device according to claim 1 , A warning processing unit is provided that distinguishes the range of the amount of wear or the amount of load into a plurality of stages and warns of the state at each stage. Physical quantity detection device.

11. The physical quantity detection device according to claim 1 , The strain sensor has a plurality of detection units arranged in a plurality of rows and a plurality of columns in the X direction and the Y direction which are orthogonal to each other. Physical quantity detection device.

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