JP4377651B2 - Method for detecting force acting on tire and pneumatic tire used therefor - Google Patents

Description

  The present invention can easily detect three translational direction forces including a longitudinal force (tire circumferential force), lateral force (tire axial force), and vertical load (radial force) acting on the tire. Thus, the present invention relates to a method of detecting a force acting on a tire that can accurately grasp the rolling condition of the tire and contribute to the control of the vehicle control system, and a pneumatic tire used therefor.

In recent years, various vehicle control systems such as ABS (anti-lock brake system), TCS (traction control system), and VSC (vehicle stability control) have been developed in order to ensure the stability and safety of a running vehicle. Yes. In order to control these systems, it is necessary to accurately grasp the rolling state of the running tire.

  For example, in ABS, it is necessary to grasp the slip condition of a tire. For this reason, in Patent Documents 1 to 3 and the like, the strain level of a tread is measured by a sensor embedded in the tread, and based on the measurement data. It has been proposed to estimate a road surface friction coefficient and a road surface contact ability of a tire related to the slip condition.

JP 2002-36836 A JP 2002-331813 A JP 2002-087032 A

  However, in such means, since the sensor is arranged in the ground contact area, the sensor tends to be damaged by an impact force or the like when riding over a projection on the road surface, and it is difficult to ensure high reliability. Moreover, the information of the measurement data cannot be applied to control of other vehicle control systems such as TCS and VSC, such as being limited to ABS control, and there is a problem that the versatility is inferior.

  Therefore, the inventor accurately grasps the rolling condition of the tire by obtaining all the external forces that the tire receives from the road surface, that is, the three translational direction forces of the longitudinal force Fx, the lateral force Fy, and the vertical load Fz. In addition, research was conducted based on the viewpoint that the information on the three translational direction forces can be applied to control of various vehicle control systems including ABS.

  As a result, it was found that the three translational direction forces can be estimated with relatively high accuracy by providing a sensor for measuring the surface strain in the sidewall portion of the tire and utilizing the measurement data of the surface strain. .

  Specifically, as schematically shown in FIGS. 12 (A) and 12 (B), the front and rear force Fx, lateral force Fy, and vertical load Fz are individually and statically applied to the tire, and the radial surface strain generated at that time is generated. εs and circumferential surface strain εt were measured at four positions, a tire equator position Pa, a tread edge position Pb, a sidewall position Pc, and a bead position Pd, respectively. As a result, as shown in Table 1, at the positions Pa and Pb of the tread portion, there is a correlation between the longitudinal force Fx, the lateral force Fy, the vertical load Fz and the surface strains εs and εt caused thereby. However, it has been found that it is difficult to estimate the longitudinal force Fx, the lateral force Fy, and the vertical load Fz from the surface strain. At the position Pd of the bead portion, there is a linear correlation between the lateral force Fy, the vertical load Fz, and the surface strain εs, but there is a correlation between the longitudinal force Fx and the surface strains εs, εt. Therefore, it has been found that it is difficult to estimate all the three translational direction forces Fx, Fy, and Fz from the surface strain even at the position Pe.

  On the other hand, at the position Pc of the sidewall portion, at least one of the surface strains εs and εt and all the three translational direction forces Fx, Fy, and Fz have a correlation in wire diameter. It was found that at the position Pc of the part, all three translational direction forces Fx, Fy, Fz can be estimated from the surface strain, that is, the rolling condition of the tire can be grasped.

  Next, FIGS. 13A to 13C illustrate the relationship between the three translational direction forces Fx, Fy, and Fz at the position Pc and the resulting surface strains εs and εt. The longitudinal force Fx and the surface strain are illustrated in FIGS. Although there is a linear correlation with εt, the displacement is small, making accurate estimation difficult. Therefore, the present inventor tried to measure the surface strain εγ in the shear direction as shown in FIG. 14A in place of the surface strains εs and εt in the radial direction and the circumferential direction. As a result, as shown in FIG. 14B, a linear correlation with a large displacement can be found between the surface strain εγ in the shear direction and the longitudinal force Fx, and the surface strain εγ is a lateral force Fy. Similarly, it was confirmed that the displacement exhibits a large linear correlation with the vertical load Fz. Therefore, in order to accurately estimate all the three translational direction forces Fx, Fy, and Fz, it is important to measure the surface strain εγ particularly in the shear direction at the position Pc of the sidewall portion.

  However, at this time, since the side wall portion is largely grounded / ungrounded, a strain gauge such as a so-called resistance wire strain gauge cannot follow the elasticity of the tire and causes problems such as breakage and peeling. Arise. Therefore, it is necessary for the sensor to be able to easily follow a large deflection and to be excellent in durability.

  Accordingly, the present invention uses a sensor in which a magnet and a magnetic sensor element facing the sensor are integrated via an elastic material, and the sensor is provided on the side wall, while maintaining high durability. It is possible to easily estimate the three translational forces of the longitudinal force, lateral force and vertical load acting on the tire, accurately grasp the rolling condition of the tire, and conveniently control various vehicle control systems. It is an object of the present invention to provide a method for detecting a force acting on a tire, and a pneumatic tire used therefor.

In order to achieve the object, the invention of claim 1 of the present application is a detection method for detecting a force acting on a tire based on a strain output of a strain sensor that is attached to the tire and detects a tire surface strain.
While providing the strain sensor in the region of the sidewall portion,
The strain sensor comprises a sensor element unit in which a magnet and a magnetic sensor element facing the magnet are integrated via an elastic material ,
In addition, the sensor element unit is arranged such that the center line where the gain of the sensor is maximum is inclined at an angle of 10 to 80 ° with respect to the radial line of the tire, so that the shear strain of the sidewall portion is also reduced. It is characterized by being detectable .

The inventions of claims 2 and 7 are characterized in that the magnetic sensor element is a Hall element.

In the inventions of claims 3 and 8, the sensor element unit is composed of one magnet and one magnetic sensor element, one magnet and a plurality of magnetic sensor elements, or a plurality of magnets and one magnetic sensor element. It is characterized by.

According to a fourth aspect of the present invention, the strain output is output for each rotational position by the rotational position detector by a rotational position detector for detecting the rotational position of the tire.

According to a fifth aspect of the present invention, the strain sensor includes at least three sensor element units arranged in the circumferential direction, and the strain output by the three sensor element units is expressed as t1, t2, t3 in the circumferential direction. In this case, the longitudinal force Fx, lateral force Fy, and vertical load Fz are obtained by the following equation (1).
┌Fx┐ ┌A1 B1 C1┐ ^-1 ┌t1┐
│Fy│ = │A2 B2 C2│ │t2│ --- (1)
└Fz┘ └A3 B3 C3┘ └t3┘

Here, A1-A3, B1-B3, C1-C3 are
t1 = A1 · Fx + B1 · Fy + C1 · Fz
t2 = A2 · Fx + B2 · Fy + C2 · Fz
t3 = A3 · Fx + B3 · Fy + C3 · Fz
Is a coefficient obtained by numerically analyzing a plurality of data of strain outputs t1, t2, and t3 actually measured by changing Fx, Fy, and Fz in advance and Fx, Fy, and Fz at that time.

The invention according to claim 6 is a pneumatic tire comprising a strain sensor used for detecting a force acting on the tire by outputting a strain output obtained by detecting the tire surface strain,
While providing the strain sensor in the region of the sidewall portion,
This strain sensor is composed of a sensor element unit in which a magnet and a magnetic sensor element facing the magnet are integrated via an elastic material ,
In addition, the sensor element unit is arranged such that the center line where the gain of the sensor is maximum is inclined at an angle of 10 to 80 ° with respect to the radial line of the tire, so that the shear strain of the sidewall portion is also reduced. It is characterized by being detectable .

In the invention of claim 9, the strain sensor has at least three sensor element units arranged in the circumferential direction.

  Since the present invention is configured as described above, it is possible to easily estimate the three translational direction forces of the longitudinal force, lateral force, and vertical load acting on the tire while maintaining high durability. It is possible to accurately grasp the rolling situation and conveniently control various vehicle control systems.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a pneumatic tire used in a method for detecting a force acting on a tire of the present invention.

  In FIG. 1, the pneumatic tire 1 includes a carcass 6 that extends from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, the inner side of the tread portion 2, and the radial direction of the carcass 6. A belt layer 7 disposed on the outside.

  The carcass 6 is formed of one or more, in this example, one carcass ply 6A in which carcass cords are arranged at an angle of, for example, 70 to 90 ° with respect to the tire circumferential direction. The carcass ply 6A includes a series of ply turn-up portions 6b that are turned back from the inside in the tire axial direction around the bead core 5 on both sides of the ply main body portion 6a straddling between the bead cores 5 and 5. A bead reinforcement bead apex rubber 8 having a triangular cross section extending from the bead core 5 outward in the tire radial direction is disposed between the portion 6a and the ply turn-up portion 6b.

  The belt layer 7 is formed of two or more belt plies, in this example, two belt plies 7A and 7B in which belt cords are arranged at an angle of, for example, 10 to 35 ° with respect to the tire circumferential direction. By crossing each other, the belt rigidity is increased, and the substantially entire width of the tread portion 2 is firmly reinforced with a tagging effect. A band layer 9 in which band cords are arranged at an angle of 5 degrees or less with respect to the circumferential direction can be provided on the outer side in the radial direction of the belt layer 7 for the purpose of improving high-speed running performance and high-speed durability. .

  In the tire 1 of this embodiment, a strain sensor 10 that detects the surface strain is provided in the region Y of the sidewall portion 3. This strain sensor 10 is formed of a plurality of sensor element units 20 of at least one or more, particularly when detecting all three translational direction forces. In the case of three or more, the sensor element units 20 can be arranged at equal intervals or at irregular intervals in the tire circumferential direction as long as they are on the same circumference around the tire axis. It is preferable from the viewpoint of simplicity of measurement control and the like, and in this example, as shown in FIG. 2, a case where eight sensor element units 20 are arranged at equal intervals is illustrated.

  Further, the region Y of the sidewall portion 3 is a region range that divides a distance L of 25% of the tire cross-sectional height H inward and outward in the radial direction around the intermediate height position M of the tire cross-sectional height H. Preferably, the distance L is set to 20% or even 15% of the tire cross-section height H, and the strain sensor 10 is provided in an area range closer to the intermediate height position M.

In this area Y, as explained with reference to FIGS. 12 and 13 and Table 1 in the [Background Art] section, the longitudinal force Fx, lateral force Fy, and vertical load Fz, which are three translational direction forces, are individually applied to the tire. The surface strain ε generated when the load is applied is a portion having a substantially linear correlation with each directional force Fx, Fy, Fz. Accordingly, in this region (region Y), the surface strain εx generated by the longitudinal force Fx can be approximated by a linear function εx = f (Fx) of the longitudinal force Fx, and similarly, the surface strain εy generated by the lateral force Fy. Is a linear function εy = f (Fy) of the lateral force Fy, and the surface strain εz generated by the vertical load Fz can be approximated by a linear function εz = f (Fz) of the vertical load Fz, respectively. Accordingly, the surface strain ε generated when the resultant force F of the three translational direction forces Fx, Fy, and Fz is applied can be approximated by the sum of the surface strains εx, εy, and εz, that is, the following equation (2). Become.
ε = f (Fx) + f (Fy) + f (Fz) −−−− (2)

  Next, as shown in FIGS. 3 to 5, the sensor element unit 20 is a block shape in which a magnet 11 and a magnetic sensor element 12 facing the magnet 11 with a gap are integrated via an elastic material 13. It is formed as a mold body.

  As the magnetic sensor element 12, a so-called semiconductor magnetic sensor such as a Hall element and an MR element (magnetoresistance effect element) can be used. In particular, a Hall element is preferably used from the viewpoints of compactness, sensitivity, and ease of handling. it can. Further, in the sensor element unit 20, it is important that the sensor element unit 20 can be elastically deformed following the movement of the sidewall portion 3, and various rubber elastic materials are employed as the elastic material 13. In particular, the thermoplastic elastomer (TPE) can be molded by plastic molding such as cast molding or injection molding, and can be suitably employed from the viewpoint of manufacturing the sensor element unit 20.

  As the sensor element unit 20, as shown in FIGS. 3A and 3B, a 1-1 type formed by one magnet 11 and one magnetic sensor element 12, and FIGS. 1-n type formed by one magnet 11 and plural (n, for example, two) magnetic sensor elements 12, as shown in FIGS. 5A and 5B, and plural (n, For example, an n-1 type formed of two magnets 11 and one magnetic sensor element 12 can be used. In the figure, reference numeral 12 s indicates the sensing part surface 12 s of the magnetic sensor element 12, reference numeral 11 s indicates the magnetic pole surface of the magnet 11, and reference numeral N indicates the center line where the gain of the sensor element unit 20 is maximum. .

  The sensor element unit 20 has an angle of 10 to 80 ° with respect to the tire radial direction line, with the center line N having the maximum gain, as shown in FIG. It is attached in a direction inclined at θ. Thereby, the shear strain εγ of the surface strain ε of the sidewall portion 3 can be detected. The angle θ is preferably 20 to 70 °, more preferably 30 to 60 °, and further preferably 40 to 50 °.

  The reason for detecting the shear strain εγ is that the shear strain εγ has a linear correlation with large displacement with respect to any of the three translational direction forces Fx, Fy, and Fz, as described in the section of “Background Art”. As a result, all of the three translational direction forces Fx, Fy, and Fz can be detected more accurately.

  Here, the attachment of the sensor element unit 20 is preferably on the outer surface side of the sidewall portion 3 as in this example, from the viewpoint of detecting surface distortion, but in FIGS. 7A and 7B, As illustrated, it can be attached by being embedded on the inner surface side or inside the tire. In any case, it is preferable to embed the tire inside the tire before vulcanization, or attach it to the inner surface or the outer surface and attach firmly by vulcanization adhesion by subsequent vulcanization. However, it can also be attached to the inner or outer surface of the vulcanized tire by bonding with an adhesive or the like.

  Reference numeral 15 in the figure denotes a sensor transmission control device that transmits the strain output of the shear strain εγ detected by the sensor element unit 20 to an electronic control unit (ECU) of a vehicle control system provided in the vehicle. These show the lead wire which connects this sensor transmission control apparatus 15 and each said sensor element unit 20. FIG. In this example, the lead wire 16 is pre-embedded and wired in the tire before vulcanization. Further, from the viewpoint of rim assembly, the sensor transmission control device 15 is preferably attached to the inner surface of the tire after vulcanization with an adhesive. It can also be attached using a mounting bracket.

  Next, a detection method for detecting the three translational direction forces of the longitudinal force Fx, lateral force Fy, and vertical load Fz acting on the tire 1 using the pneumatic tire 1 will be described.

First, when the resultant force F of the three translational direction forces Fx, Fy, Fz is applied, between the surface strain ε generated in the region Y of the sidewall portion 3 and the three translational direction forces Fx, Fy, Fz at that time, As described above, there is a relationship represented by the following expression (2).
ε = f (Fx) + f (Fy) + f (Fz) −−−− (2)

  Then, in order to derive the three translational direction forces Fx, Fy, and Fz that form the resultant force F from the surface strain ε that can be measured by the sensor element unit 20, three formulas (2) that use Fx, Fy, and Fz as unknowns are obtained. This can be achieved by solving the original linear equation. However, to solve this ternary linear equation, three simultaneous equations are necessary.

Therefore, in the detection method of the present invention, at least three sensor element units 20 are arranged in the circumferential direction in the region Y of the sidewall portion 3, and three sensor element units 20 a, 20 b, and 20 c among them are 3 The shear strain εγ when the resultant force F of the translational direction forces Fx, Fy, and Fz acts is also measured (detected) at the same time. At this time, if the strain outputs detected by the sensor element units 20a, 20b, and 20c are t1, t2, and t3, the following three simultaneous equations can be obtained based on the equation (2). A1 to A3, B1 to B3, and C1 to C3 are coefficients.
t1 = A1 · Fx + B1 · Fy + C1 · Fz
t2 = A2 · Fx + B2 · Fy + C2 · Fz
t3 = A3 · Fx + B3 · Fy + C3 · Fz
From these three simultaneous equations, the following determinant (1) for obtaining Fx, Fy, and Fz can be obtained.
┌Fx┐ ┌A1 B1 C1┐ ^-1 ┌t1┐
│Fy│ = │A2 B2 C2│ │t2│ --- (1)
└Fz┘ └A3 B3 C3┘ └t3┘

  Accordingly, the shear strain εγ is also measured simultaneously with the predetermined three sensor element units 20a, 20b, and 20c, and the three strain outputs t1, t2, and t3 obtained thereby are substituted into the equation (1). The longitudinal force Fx, lateral force Fy, and vertical load Fz can be obtained respectively.

  The coefficients A1 to A3, B1 to B3, and C1 to C3 are the strain outputs t1, t2, and t3 measured by changing the longitudinal force Fx, lateral force Fy, and vertical load Fz in the prior load application test, and at that time Can be obtained by numerical analysis of a plurality of data of the longitudinal force Fx, lateral force Fy, and vertical load Fz. That is, in the prior load application test, for example, the longitudinal force Fx, the lateral force Fy, and the vertical load Fz are individually and statically applied to the tire 1, and the sensor element units 20a, 20b, and 20c detected at that time are detected. Record distortion outputs t1, t2, and t3. This can be repeated by changing the longitudinal force Fx, lateral force Fy, and vertical load Fz, respectively, and obtaining a plurality of obtained data by numerical conversion using, for example, a computer.

  In order to verify this detection method, as shown in FIG. 8, the present inventor made a prototype of a tire in which three sensor element units 20a, 20b, and 20c are arranged with a center angle α of 90 ° from each other. In the polar coordinate system around the tire axis center with the lowest end of the tire being 0 ° (reference point P0), the tire was fixed at a rotational position where the central sensor element unit 20b becomes the reference point P0. Then, a prior load application test is performed on the tire at the rotational position (stationary state), and by calculating the coefficients A1 to A3, B1 to B3, and C1 to C3, a unique formula (1) is derived for each rotational position. It was.

  Thereafter, as shown in FIGS. 9 (A) and 9 (B), the three translational direction forces Fx, Fy, and Fz are applied to the tire in the rotational position (stationary state) while changing over time, and the sensor element From the strain outputs t1, t2, and t3 measured by the units 20a, 20b, and 20c, the calculated value of the three translational direction forces was calculated using Equation (1). The calculated values were compared with the three translational forces actually applied in the same figure. As a result, it was confirmed that the three translational forces Fx, Fy and Fz acting on the tire can be detected by the detection method.

  Here, the coefficients A1 to A3, B1 to B3, and C1 to C3 are coefficients specific to the rotational position determined for each rotational position of the tire, and accordingly, the three sensor element units when performing a prior load application test. The rotational positions of 20a, 20b, and 20c and the rotational positions of the three sensor element units 20a, 20b, and 20c when detecting the three translational direction forces Fx, Fy, and Fz are both the same position (90 ° in this example, 0 °, 270 °). Therefore, when detecting three translational direction forces Fx, Fy, and Fz in a running tire that actually rotates, a rotational position detector 18 such as an encoder that detects the tire rotational position on the tire, wheel, axle, or the like. It is preferable to attach (shown in FIG. 1) and output the strain outputs t1, t2, and t3 for each predetermined rotational position detected by the rotational position detector 18.

  As for the rotational position, as shown in FIG. 8, the central sensor element unit 20b of the three sensor element units 20a, 20b, and 20c is set to the reference point P0 closest to the ground point, and both sides The sensor element units 20a and 20c are preferably arranged at symmetrical positions around the reference point P0 in the circumferential direction. If the sensor element units 20a, 20b, and 20c are too close to each other, it is difficult to detect the three translational direction forces Fx, Fy, and Fz with high accuracy. For this reason, the sensor element units 20a, 20b, and 20c are 90 ° apart from each other. It is preferable to arrange them at a central angle α. In particular, as in this example shown in FIG. 2, when 4 × n (n is an integer) sensor element units 20 are used and arranged at equal intervals in the circumferential direction, the tire is 90 / n °. As the sensor element units 20a, 20b, and 20c are rotated at 0 °, 90 °, and 270 ° as shown in FIG. 8 each time they rotate, three translational direction forces Fx, Fy, and Fz are generated every 90 / n ° rotation. Can be detected, and it is possible to cope with a sudden change in the tire rolling condition.

  Next, FIGS. 10A and 10B show an example of the result of a detection experiment when three translational direction forces Fx, Fy, and Fz are detected from a tire that actually rotates. In this detection experiment, as shown in FIG. 10A, four sensor element units 20A to 20D are arranged in the circumferential direction at intervals of 90 °, and the three translational direction forces Fx, Fy, and Fz are changed on the rotating tire. While continuously loaded. In the four states QA to QD in which the sensor element units tA to tD are rotated at 0 °, 90 °, 180 °, and 270 °, distortion outputs t1 and t2 are obtained at three positions of 0 °, 90 °, and 270 °, respectively. , T3, and the three translational direction forces FxA to FxD, FyA to FyD, and FzA to FzD are calculated from the strain outputs t1, t2, and t3 using Equation (1), and the three translational direction forces actually applied are calculated. Comparison with Fx, Fy and Fz. As shown in the figure, it can be confirmed that the three translational direction forces Fx, Fy, Fz acting on the rotating tire can be estimated by measuring the strain outputs t1, t2, t3.

  Next, FIG. 11 illustrates an example of a preferred configuration diagram when the vehicle control system is controlled using the detection method of the present invention. In this configuration diagram, eight sensor element units 20 are arranged at equal intervals in the circumferential direction on one sidewall portion 3 of each tire 1 mounted on a vehicle. Each sensor element unit 20 is connected to, for example, a sensor transmission control device 15 attached to the inner surface of the tire, and strain outputs t1, t2 from the sensor element unit 20 at predetermined three positions (for example, 0 °, 90 °, 270 °), t3 is transmitted to the electronic control unit 19A of the vehicle control system 19 provided in the vehicle.

  Here, in this example, the sensor transmission control device 15 is based on the detection of the tire rotational position by the rotational position detector 18, and the strain output t1 of the sensor element units 20a, 20b, 20c at the predetermined three positions, Switching means 15A for selecting t2, t3, an amplifier 15B for amplifying the selected distortion outputs t1, t2, t3, a transmitter 15C for transmitting the amplified signal to the vehicle side, and a power source (not shown) for operating them Consists of. As the power source, various types of batteries can be used. For example, a storage battery and a converter that converts electromagnetic waves transmitted from a vehicle into direct current power and charges the storage battery can be used from the viewpoint of maintenance and the like. preferable.

  The vehicle control system 19 includes a receiver 19B that receives the distortion outputs t1, t2, and t3 from the sensor transmission control device 15 and sends them to the electronic control device 19A. The electronic control unit 19A calculates the three translational direction forces Fx, Fy, and Fz using the formula (1) on the basis of the sent strain outputs t1, t2, and t3, and based on the calculation results. Control vehicle control systems such as ABS, TCS, VSC, for example. The electronic control unit 19A includes a storage unit that stores Equation (1) having preset coefficients A1 to A3, B1 to B3, and C1 to C3, and Equation (1) and distortion outputs t1, t2, and at least a calculation unit that calculates three translational direction forces Fx, Fy, and Fz from t3. The tire rotation position detection data by the rotation position detector 18 is transmitted to the switching means 15A via the electronic control unit 19A, the transmitter 30 and the receiver 31, and the sensor element units 20a, 20b and 20c to be selected are transmitted. specify.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

It is sectional drawing which shows the pneumatic tire used for the detection method of the force which acts on the tire of this invention. It is a side view of the pneumatic tire which shows the arrangement state of a sensor element unit schematically. (A), (B) is the top view and perspective view which show one Example of a sensor element unit. (A), (B) is the top view and perspective view which show the other Example of a sensor element unit. (A), (B) is the top view and perspective view which show other Example of a sensor element unit. It is a diagram which shows the attachment direction of a sensor element unit. (A), (B) is a diagram explaining the attachment position of a sensor element unit. It is a diagram which shows the rotational position of three sensor element units used for the detection of 3 translational direction force. (A) and (B) are graphs comparing the three translational direction forces actually loaded with the calculated value of the three translational direction forces calculated from the strain output at that time. (A), (B) is a graph explaining an example of a detection experiment for detecting three translational direction forces Fx, Fy, Fz from a tire that actually rotates, and a graph showing the results. It is an example of the block diagram in the case of controlling a vehicle control system using the detection method of this invention. (A), (B) is a diagram explaining the load load test implemented in order to obtain | require the relationship between the surface distortion at the time of applying 3 translation direction force to a tire, and the 3 translation direction force loaded at that time. is there. (A)-(C) are graphs which illustrate the relationship between the three translational direction force in the position of a sidewall part, and the surface strain of radial direction and circumferential direction by it. (A) and (B) are the graph which illustrates the relationship between the surface strain of a shear direction, and the longitudinal force, and the diagram explaining the surface strain of a shear direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tire 3 Side wall part 10 Strain sensor 11 Magnet 12 Magnetic sensor element 13 Elastic material 18 Rotation detector 20 Sensor element unit N Center line Y area | region

Claims (9)

A detection method for detecting a force acting on a tire by a strain output of a strain sensor that is attached to the tire and detects a tire surface strain,
While providing the strain sensor in the region of the sidewall portion,
The strain sensor comprises a sensor element unit in which a magnet and a magnetic sensor element facing the magnet are integrated via an elastic material ,
In addition, the sensor element unit is arranged such that the center line where the gain of the sensor is maximum is inclined at an angle of 10 to 80 ° with respect to the radial line of the tire, so that the shear strain of the sidewall portion is also reduced. A method for detecting a force acting on a tire, characterized by being detectable.   2. The method for detecting force acting on a tire according to claim 1, wherein the magnetic sensor element is a Hall element.   3. The sensor element unit includes one magnet and one magnetic sensor element, one magnet and a plurality of magnetic sensor elements, or a plurality of magnets and one magnetic sensor element. Of detecting the force acting on the tire. The said distortion output acts on the tire in any one of Claims 1-3 output for every rotation position by this rotation position detector by the rotation position detector which detects the rotation position of a tire. Force detection method. The strain sensor has at least three sensor element units arranged in the circumferential direction, and when the strain output by the three sensor element units is t1, t2, and t3 in the circumferential direction, the following formula (1 The longitudinal force Fx, the lateral force Fy, and the vertical load Fz are obtained by the following method: A method for detecting a force acting on a tire according to any one of claims 1 to 4 .
┌Fx┐ ┌A1 B1 C1┐ ^-1 ┌t1┐
│Fy│ = │A2 B2 C2│ │t2│ --- (1)
└Fz┘ └A3 B3 C3┘ └t3┘

Here, A1-A3, B1-B3, C1-C3 are
t1 = A1 · Fx + B1 · Fy + C1 · Fz
t2 = A2 · Fx + B2 · Fy + C2 · Fz
t3 = A3 · Fx + B3 · Fy + C3 · Fz
Is a coefficient obtained by numerically analyzing a plurality of data of strain outputs t1, t2, and t3 actually measured by changing Fx, Fy, and Fz in advance and Fx, Fy, and Fz at that time. A pneumatic tire including a strain sensor used for detecting a force acting on a tire by outputting a strain output obtained by detecting tire surface strain,
While providing the strain sensor in the region of the sidewall portion,
This strain sensor is composed of a sensor element unit in which a magnet and a magnetic sensor element facing the magnet are integrated via an elastic material ,
In addition, the sensor element unit is arranged such that the center line where the gain of the sensor is maximum is inclined at an angle of 10 to 80 ° with respect to the radial line of the tire, so that the shear strain of the sidewall portion is also reduced. A pneumatic tire characterized by being detectable . The pneumatic tire according to claim 6, wherein the magnetic sensor element is a Hall element. The sensor element unit, one magnet and one magnetic sensor element, one magnet and a plurality of magnetic sensor elements, or a plurality of magnets and claim 6 or 7, wherein the consisting of one magnetic sensor element Pneumatic tires. The pneumatic tire according to any one of claims 6 to 8 , wherein the strain sensor has at least three sensor element units arranged in a circumferential direction.

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