Tire comprising sensor unit

Abstract

To provide a tire comprising a sensor unit that can determine a deflection of the tire, with high accuracy, without being influenced by eddy currents caused by an external connection terminal, on the presumption that the deflection of the tire is determined using signals outputted from a plurality of magnetic sensor elements.SOLUTION: A sensor unit (10) includes a flexible sheet (16) with non-stretchability that is a nonmagnetic material, one permanent magnet (12) formed on the flexible sheet, at least two magnetic sensor elements (14a and 14b) and at least one external connection terminals (18a-18b), where at least one magnetic sensor element is arranged in each of a region at one side and a region at the other side respectively of a sheet surface reference line in a concave circle. At least one external connection terminals are arranged away from the sheet surface reference line more than the magnetic sensor elements connected to each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a tire equipped with a sensor unit that allows the deflection to be determined with high precision. [Background technology]

[0002] Conventionally, tire sensor units have been disclosed that include a substrate formed into a generally sheet-like shape from a flexibly deformable material and to be placed on a tire, and a sensor that is attached to the substrate and detects strain (deflection) of the tire (for example, Patent Document 1, Figure 2).The tire sensor unit of Patent Document 1 can be installed on a tire through the simple process of installing the substrate with the sensor on the tire, which makes it easy to install the tire sensor unit on the tire and maintains good tire productivity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-64565 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the tire sensor unit of Patent Document 1, the sensor is composed of one magnet and one magnetic sensor element. Therefore, tire deflection must be determined based on one signal output from the magnetic sensor element, and there is a risk that tire deflection cannot be determined with high accuracy, particularly when the tire exhibits complex deformation behavior, such as when stress is applied to the tire from multiple directions.

[0005] Furthermore, when determining the deflection of an object based on changes in magnetic flux density near a specific region of the object, if an electronic circuit is used to process information about the measured magnetic flux density into information about the deflection, the external connection terminals connected to the electronic circuit may generate eddy currents (noise). The generation of these eddy currents can lead to noise being mixed into the power supplied to the electronic circuit and the signals processed by the electronic circuit, which may in turn adversely affect the deflection determination by the magnetic sensor element. For this reason, in recent years, there has been a demand for determining the deflection of an object while minimizing the influence of the above-mentioned eddy currents in order to determine the deflection of an object with higher accuracy.

[0006] The present invention has been made in consideration of the above circumstances, and its object is to provide a tire equipped with a sensor unit that can determine tire deflection with high accuracy without being affected by eddy currents due to external connection terminals, on the premise that tire deflection is determined using signals output from multiple magnetic sensor elements. [Means for solving the problem]

[0007] The tire of the present invention is a tire having a sensor unit on a tire cavity surface that determines the deflection of the tire during bending deformation of the tire, the sensor unit includes a non-magnetic, non-stretchable flexible sheet, one permanent magnet, at least two magnetic sensor elements, and at least one external connection terminal, which are formed on the flexible sheet; The deflection of the tire is determined by performing a calculation using signals output from each of the at least two magnetic sensor elements; determining a concave circle formed by projecting onto the tire surface a circle that is centered on the center of gravity of the permanent magnet, is included in a plane perpendicular to a straight line that includes a perpendicular line extending from the center of gravity to the tire surface, and has a radius that is the longest distance between this straight line and the magnetic sensor element; Next, when a line including the diameter of the concave circle with the largest radius of curvature is defined as a seat surface reference line, at least one magnetic sensor element is disposed in each of regions on one side and the other side of the seat surface reference line within the concave circle, The at least one external connection terminal is characterized in that it is disposed farther from the seat surface reference line than the magnetic sensor element to which it is connected. [Effects of the Invention]

[0008] In the tire according to the present invention, two or more magnetic sensor elements are included in one sensor unit, which makes it possible to compare the signal values ​​output from each magnetic sensor element over time, or to compare the differences in the signal values ​​output from multiple magnetic sensor elements over time, and by combining the signal values ​​output from multiple magnetic sensor elements, it is possible to determine the tire deflection with high accuracy even when the tire exhibits complex deformation behavior.

[0009] In addition, in the tire according to the present invention, at least one external connection terminal is disposed farther from the sheet surface reference line than the magnetic sensor element to which it is connected. This prevents eddy currents from being generated in the external connection terminal that is subjected to the magnetic field generated by the permanent magnet, and prevents noise from being mixed into the signals output from the magnetic sensor elements. This makes it possible to determine tire deflection with high accuracy without reducing sensitivity in sensing tire bending deformation. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a meridian cross-sectional view of a tire according to the present embodiment. [Figure 2] FIG. 2 is a diagram showing the three-dimensional positional relationship between the permanent magnet and the magnetic sensor element when the sensor unit is placed on the tire cavity surface. [Figure 3] Figure 3 is a plan view showing a sensor unit, where (A) shows an example in which one magnetic sensor element is arranged on each side of the seat surface reference line, and (B) shows an example in which two magnetic sensor elements are arranged on each side of the seat surface reference line. [Figure 4]Figure 4 is a plan view showing a sensor unit, where (A) shows an example (a suitable example) in which the electrical wiring connecting the magnetic sensor element and the external connection terminal does not intersect with the sheet surface reference line, and (B) shows an example (an unsuitable example) in which the electrical wiring connecting the magnetic sensor element and the external connection terminal intersects with the sheet surface reference line. [Figure 5] Figure 5 is a plan view showing a sensor unit, where (A) and (B) show an example (suitable example) in which the external connection terminals are arranged at the longitudinal ends on each side of the sheet surface reference line, and (C) shows an example (unsuitable example) in which the external connection terminals are not arranged at the longitudinal ends on one side of the sheet surface reference line. [Figure 6] FIG. 6 is a plan view of the sensor unit, showing examples of flexible sheets in the shapes of (A) a rectangle, (B) a pentagon, (C) an ellipse, (D) a trapezoid, and (E) an H-shape. [Figure 7] Figure 7 is a plan view of a sensor unit, where (A) shows an example in which a single row of external connection terminals is aligned on a rectangular flexible sheet, (B) shows an example in which one and two rows of external connection terminals are aligned on a rectangular flexible sheet, and (C) shows an example in which a single row of external connection terminals is aligned on an H-shaped flexible sheet. [Figure 8] FIG. 8 is a plan view of the sensor unit, showing the relationship between the width V at the position of the seat surface reference line L1 and the maximum width dimension Wmax in the direction of the seat surface reference line L1. [Figure 9] FIG. 9 is a diagram showing the state of adhesion of the flexible sheet on the tire cavity surface. [Figure 10] Figure 10 is a diagram showing the positional relationship between the permanent magnet and the magnetic sensor element before and after placing a flexible sheet (sensor unit) on the tire cavity surface, and shows an example in which the magnetization direction is parallel to the flexible sheet before placement. [Figure 11] FIG. 11 shows suitable examples (A) and (B) of the position of the magnetic sensor element and an inappropriate example (C) of the position of the magnetic sensor element when the sensor unit is disposed on the surface of the tire. [Figure 12] FIG. 12 is a tire meridian cross section showing a part of the tire of this embodiment. [Figure 13]FIG. 13 is a diagram showing a circle passing through the centers of gravity of the permanent magnet and the two magnetic sensor elements that constitute the sensor unit. [Figure 14] Figure 14 is a tire meridian cross section showing the position of a reference line on the tire cavity surface, where (A) shows an example in which not only the reference line but also the magnetic sensor element on the inner side in the tire width direction is located within a predetermined range, while (B) shows an example in which the magnetic sensor element on the inner side in the tire width direction is not located within the predetermined range. [Figure 15] FIG. 15 is a meridian cross section of a tire showing the position of a reference line on the tire cavity surface and the position of an end of a flexible sheet on the tread surface and closer to a point on the tire equatorial plane. [Figure 16] Figure 16 is a diagram showing the positional relationship between a permanent magnet, a magnetic sensor element, and a belt, where (A) shows the positional relationship between the magnetic sensor element and the belt, and (B) shows the positional relationship between the permanent magnet and the magnetic sensor element. [Figure 17] FIG. 17 is a diagram showing the relationship between the sheet surface reference line and the three directions of the permanent magnet. [Figure 18] FIG. 18 is a meridian cross section of a tire showing the relationship between the dimensions of the permanent magnet and the tire thickness. [Figure 19] Figure 19 is a meridian cross section of a tire showing suitable positions for placing a circuit board connected to a sensor unit, where (A) shows an example in which the circuit board is placed closer to the center of the tread than an area where it is undesirable to place it, and (B) shows an example in which the circuit board is placed closer to the bead than an area where it is undesirable to place it. [Figure 20] Figure 20 is a plan view showing the positions of magnetic sensor elements in a sensor unit, where (A) shows an example in which two magnetic sensor elements are arranged in a predetermined area, (B) shows an example in which two more magnetic sensor elements are arranged in an area other than the predetermined area in the example shown in (A), (C) shows an example in which three magnetic sensor elements are arranged in a predetermined area, and (D) shows an example in which four magnetic sensor elements are arranged in a predetermined area. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the tire according to the present invention (Basic Embodiment 1 and Additional Embodiments 2 to 18 shown below) will be described in detail with reference to the drawings. Note that these embodiments do not limit the present invention. Furthermore, the components of each embodiment include those that are easily replaceable by a person skilled in the art, or those that are substantially identical. Furthermore, each embodiment can be arbitrarily combined within the scope of what is obvious to a person skilled in the art.

[0012] In the following description, the tire radial direction refers to the direction perpendicular to the tire rotational axis, the tire radial inner side refers to the side toward the tire rotational axis in the tire radial direction, and the tire radial outer side refers to the side away from the tire rotational axis in the tire radial direction. The tire circumferential direction refers to the direction around the tire rotational axis as the central axis. Furthermore, the tire width direction refers to the direction parallel to the tire rotational axis, the tire width inner side refers to the side toward the tire equatorial plane (tire equator line) in the tire width direction, and the tire width outer side refers to the side away from the tire equatorial plane in the tire width direction. The tire equatorial plane refers to the plane that is perpendicular to the tire rotational axis and passes through the center of the tire width.

[0013] Similarly, in the following description, a regular rim refers to an "applicable rim" as defined by JATMA, a "design rim" as defined by TRA, or a "measuring rim" as defined by ETRTO.

[0014] Similarly, in the following explanation, "normal internal pressure" refers to the "maximum air pressure" specified by JATMA, the maximum value specified in "Tire Load Limits at Various Cold Inflation Pressures" specified by TRA, or the "Inflation Pressures" specified by ETRTO. Also, "normal load" refers to the "maximum load capacity" specified by JATMA, the maximum value specified in "Tire Load Limits at Various Cold Inflation Pressures" specified by TRA, or the "Load Capacity" specified by ETRTO.

[0015] Although not shown in detail, the tire described below has, in a tire meridian cross section, a bead portion, a sidewall portion, a shoulder portion, and a tread portion from the inner side to the outer side in the tire radial direction, and similar to a normal tire, has, for example, a carcass extending from the tread portion to the bead portions on both sides and wound around a pair of bead cores, and a belt and a belt reinforcing layer formed sequentially on the outer side in the tire radial direction of the carcass.

[0016] The tire of this embodiment is obtained through the usual manufacturing steps, namely, a tire material mixing step, a tire material processing step, a green tire molding step, a vulcanization step, and a post-vulcanization inspection step.

[0017] [Basic form 1] Fig. 1 is a meridian cross-sectional view of a tire according to this embodiment. The tire 20 shown in the figure is provided with a sensor unit 10 on the tire cavity surface, which determines the deflection of the tire during bending deformation. The sensor unit 10 is a unit including a non-magnetic, non-stretchable flexible sheet 16, one permanent magnet 12, at least two (two in the figure) magnetic sensor elements 14 (14a, 14b), and at least one (two in the figure) external connection terminal 18 (18a, 18b), all of which are formed on the flexible sheet 16.

[0018] The two magnetic sensor elements 14a, 14b detect changes in magnetic flux density before and after bending deformation of the tire 20. Based on this change in magnetic flux density, signals output from the magnetic sensor elements 14a, 14b are calculated by an arithmetic circuit via, for example, an amplifier circuit (not shown), to determine the deflection of the tire. The magnetic sensor elements 14 may be Hall elements, magnetic resistance elements, or the like.

[0019] Flexible sheet 16 can be a resin film with a high elastic modulus, etc. External connection terminal 18 is a contact portion where a cable or connector that electrically connects flexible sheet 16 to another electronic device is connected, and corresponds to a pad or the like with a partially exposed conductor.

[0020] When a tire 20 equipped with the sensor unit 10 shown in FIG. 1 is bent, the deflection of the tire is determined by performing calculations using signals output from at least two magnetic sensor elements 14a and 14b.

[0021] FIG. 2 shows the three-dimensional positional relationship between the permanent magnet and the magnetic sensor element when the sensor unit is placed on the tire cavity surface. For ease of explanation, the flexible sheet 16 and external connection terminals 18 are omitted from the figure. As shown in the figure, a circle is projected onto the concave curved surface of the flexible sheet 16. The circle is centered at the center of gravity G of the permanent magnet 12 and is included in a plane perpendicular to a line including a perpendicular line from the center of gravity G to the tire surface. The circle has a radius equal to the longest distance between this line and the magnetic sensor element 14a (or 14b). The sheet surface reference line L1 is then determined as the line including the diameter of the concave circle C with the largest radius of curvature. In this specification, "projection" refers to the projection of a circle, line, contour, or other figure as a source of projection, as a shadow on the target surface when parallel light is irradiated from the opposite side of the target surface. The light is irradiated in a direction perpendicular to the tangent plane including the center of gravity on the target plane (specific area). The direction of the sheet surface reference line L1 does not depend on the longitudinal direction or shape of the flexible sheet 16.

[0022] Here, when determining the longest distance from the center of gravity G of the permanent magnet 12 to the magnetic sensor element 14a (or 14b) that is farthest from the permanent magnet 12, the entire magnetic sensor element 14a (or 14b) is included within the concave circle C. In other words, this distance is the distance between the center of gravity G of the permanent magnet 12 and the point farthest from the center of gravity G on the magnetic sensor element 14a (or 14b) that is farthest from the center of gravity G.

[0023] In addition, in this embodiment, the concave curved surface (tire cavity surface) of the tire 20 on which the sensor unit 10 is arranged means the tire cavity surface when the tire 20 is not deformed, more specifically, the tire cavity surface when the tire is mounted on a regular rim and pressurized to the regular internal pressure, in an unloaded state (non-contact state).

[0024] Under this premise, at least one magnetic sensor element 14a, 14b is arranged in each of the regions on one side and the other side of the seat surface reference line L1 within the concave circle C.

[0025] FIG. 3 is a plan view showing a sensor unit of this embodiment, where (A) shows an example in which one magnetic sensor element is arranged on each side of the seat surface reference line, and (B) shows an example in which two magnetic sensor elements are arranged on each side of the seat surface reference line. In both examples shown in the figure, at least one external connection terminal 18 (18a to 18p) is arranged farther from the seat surface reference line L1 than the magnetic sensor elements 14 (14a to 14d) to which it is connected. In FIG. 3, each line connecting the magnetic sensor element 14 and the external connection terminal 18 is an electrical wiring EW. Note that in FIG. 3, the symbol EW is assigned to only some of the electrical wiring, and this is also true in other figures.

[0026] (effect, etc.) A conventional sensor unit such as that described in Patent Document 1 includes only one magnetic sensor element that detects changes in magnetic flux density when a tire deforms, and therefore can only realize a very simple mode for determining tire deformation behavior. However, in reality, the way in which stress, which is a prerequisite for tire deformation behavior, is applied to a tire can be from multiple directions, not just one direction, and in such cases, there is a risk that the conventional sensor unit will not be able to determine tire deflection with high accuracy.

[0027] Under such circumstances, the inventor has discovered that by including two or more magnetic sensor elements 14 that detect changes in magnetic flux density within the sensor unit 10, it is possible to implement a more complex determination method for determining the deformation behavior of the tire 20.

[0028] The sensor unit 10 based on the inventor's knowledge can determine the deflection of the tire 20 with high accuracy even when the tire 20 exhibits complex deformation behavior, such as when stress is applied to the tire 20 from multiple directions rather than just one direction.

[0029] The number of magnetic sensor elements 14 in the sensor unit 10 and the locations of the magnetic sensor elements 14 relative to the permanent magnet 12 can be changed as appropriate depending on the direction and magnitude of bending deformation to be determined. However, even if five or more magnetic sensor elements 14 are arranged in the sensor unit 10, the results of determining the deflection of the tire 20 do not differ significantly from when four magnetic sensor elements 14 are arranged. Therefore, taking into consideration manufacturing costs, etc., it is preferable that the number of magnetic sensor elements 14 in the sensor unit 10 be four or less.

[0030] Next, as described above, the sheet surface reference line L1 is a line that includes the diameter with the largest curvature among the diameters of the concave circle C of the flexible sheet 16. Among the regions of the flexible sheet 16, the region near the sheet surface reference line L1 is the region that is least susceptible to bending deformation in the length direction of the sheet surface reference line L1 when the tire 20 is bent, but is the region that is most susceptible to bending deformation in the direction perpendicular to the sheet surface reference line L1 and where the change in curvature is greatest.

[0031] Considering that the sensor unit 10 is disposed on the concave curved surface of the tire 20 (see FIG. 1), the seat surface reference line L1 is usually assumed to be a curve, but the seat surface reference line L1 may also be a straight line.

[0032] By arranging at least one magnetic sensor element 14a, 14b in each of the areas on one side and the other side of the sheet surface reference line L1, bending deformation of the tire 20 can be detected over a wider range than when the magnetic sensor element is arranged in an area only on one side, which results in increased sensitivity in sensing bending deformation of the tire 20 and ultimately enables the deflection of the tire 20 to be determined with high accuracy.

[0033] In the example shown in Figure 2, one magnetic sensor element 14a is arranged on one side of the seat surface reference line L1 and one magnetic sensor element 14b is arranged on the other side, but this embodiment is not limited to this case, and (two, one), (two, two), ..., (m, n (m is a natural number greater than or equal to 2, n is a natural number greater than or equal to 1)) magnetic sensor elements 14 may be arranged on (one side, the other side) of the seat surface reference line L1.

[0034] Next, when the sensor unit 10 including the permanent magnet 12 and the magnetic sensor element 14 is arranged so as to follow the bending deformation of the tire 20 (for example, when the permanent magnet 12 and the magnetic sensor element 14 are embedded in the tire cavity surface, or when the permanent magnet 12 and the magnetic sensor element 14 are arranged in the tire 20 via an elastic sheet), the change in magnetic flux density detected by each magnetic sensor element 14 is affected by both the expansion / contraction deformation and the bending deformation of the deformation behavior of the sensor unit 10, that is, the detection is based on all of the deformation behavior of the actual tire 20.

[0035] In contrast, when the permanent magnet 12 and at least two magnetic sensor elements 14 (14a to 14d) are arranged on the tire 20 via a non-magnetic, non-stretchable flexible sheet 16, the change in magnetic flux density detected by each magnetic sensor element 14 is affected almost exclusively by bending deformation, which is one of the deformation behaviors of the sensor unit 10; that is, the change in magnetic flux density detected by each magnetic sensor element 14 is detected in a manner that focuses almost exclusively on bending deformation, which is one of the deformation behaviors of the actual tire 20. Therefore, according to this embodiment, bending deformation of the tire 20 can be extracted more easily, and as a result, the sensitivity of sensing bending deformation of the tire 20 can be increased, and ultimately the deflection of the tire 20 can be determined with high accuracy.

[0036] The tensile modulus of flexible sheet 16 is preferably 20 times or more the tensile modulus of the placement surface material of tire 20 on which flexible sheet 16 is placed, from the viewpoint that deformation of flexible sheet 16 can be ignored compared to deformation of tire 20, and is most preferably 50 times or more. It is more preferable that the tensile modulus of flexible sheet 16 is 1 GPa or more (measured by a tensile test specified in ASTM D882).

[0037] Additionally, in this embodiment, at least one external connection terminal 18 (18a to 18p) is disposed farther from the sheet surface reference line L1 than the magnetic sensor elements 14 (14a to 14d) to which it is connected. This prevents eddy currents from being generated in the external connection terminals that are subjected to the magnetic field generated by the permanent magnets 12, and prevents noise from being mixed into the signals output from the magnetic sensor elements 14. This makes it possible to determine the deflection of the tire 20 with high accuracy without reducing the sensitivity for sensing the bending deformation of the tire 20.

[0038] [Additional Form 2] Figure 4 is a plan view showing a sensor unit, where (A) shows an example (a suitable example) in which the electrical wiring connecting the magnetic sensor element and the external connection terminal does not intersect with the sheet surface reference line, and (B) shows an example (an unsuitable example) in which the electrical wiring connecting the magnetic sensor element and the external connection terminal intersects with the sheet surface reference line.

[0039] In basic form 1, as shown in Figure 4(A), it is preferable that the electrical wiring EW connecting the magnetic sensor element 14 (14a to 14c) and the external connection terminal 18 (18a to 18p) does not intersect with the seat surface reference line L1 (additional form 2).

[0040] As shown in Figure 4(A), since the electrical wiring EW does not intersect with the sheet surface reference line L1, eddy currents are generated in the electrical wiring EW when it is subjected to the magnetic field formed by the permanent magnet 12, and noise is prevented from being mixed into the signals output from each magnetic sensor element 14. This further suppresses a decrease in sensitivity for sensing bending deformation of the tire 20, and enables the deflection of the tire 20 to be determined with even higher accuracy.

[0041] 4(B), when the electric wiring EW intersects with the sheet surface reference line L1, an eddy current is generated in the electric wiring EW that is subjected to the magnetic field generated by the permanent magnet 12, and there is a high possibility that noise will be mixed into the signals output from each magnetic sensor element 14. Therefore, in this case, there is a risk that the sensitivity for sensing the bending deformation of the tire 20 will decrease, and it may not be possible to determine the deflection of the tire 20 with a higher degree of accuracy.

[0042] 4(A), the external connection terminals 18 are dispersedly disposed at both ends of the sheet surface reference line L1, which allows the width (dimension in the short direction) of the flexible sheet 16 to be smaller than when the external connection terminals 18i to 18l are located on one side of the sheet surface reference line L1. This allows the area of ​​the flexible sheet 16 disposed on the inner cavity surface of the tire 20 to be reduced, which prevents the flexible sheet 16 (and therefore the sensor unit 10) from falling off from the tire 20 when the tire 20 is bent and deformed, thereby increasing the durability of the tire 20.

[0043] [Additional Form 3] Figure 5 is a plan view showing a sensor unit, where (A) and (B) show an example (suitable example) in which the external connection terminals are arranged at the longitudinal ends on each side of the sheet surface reference line, and (C) shows an example (unsuitable example) in which the external connection terminals are not arranged at the longitudinal ends on one side of the sheet surface reference line.

[0044] In basic form 1 or a form in which additional form 2 is added to basic form 1, it is preferable that the multiple external connection terminals 18 (18a to 18l) are aligned at the longitudinal end on at least one side of the sheet surface reference line L1 (additional form 3), as shown in Figures 5(A) and (B).

[0045] Here, aligning the external connection terminals 18 (18a to 18l) at the longitudinal end on at least one side of the sheet surface reference line L1 means that the external connection terminals 18 are arranged in one or more rows at the longitudinal end of the flexible sheet 16 and are arranged generally parallel to the sheet surface reference line L1, as shown in Figures 5(A) and 5(B). Furthermore, the above-mentioned "generally parallel" means that a range of ±30° is allowed with respect to the sheet surface reference line L1.

[0046] In this way, when arranging the external connection terminals 18 on the flexible sheet 16, by arranging the external connection terminals 18 on lines (L41 to L46 shown in Figure 5) parallel to the line that is most likely to become the axis of bending deformation (i.e., the sheet surface reference line L1) when the flexible sheet 16 deforms in response to the bending deformation of the tire, it is possible to minimize deformation of the solder and connectors connected to the external connection terminals 18, and to prevent the solder and connectors from falling off the flexible sheet 16, thereby increasing the durability of the solder and connectors.

[0047] In contrast, as shown in Figure 5(C), when arranging the external connection terminals 18 on the flexible sheet 16, if the external connection terminals 18 are arranged on a line (L47 shown in Figure 5(C)) perpendicular to the line that is most likely to become the axis of bending deformation when the flexible sheet 16 deforms in response to the bending deformation of the tire (i.e., the sheet surface reference line L1), it is not possible to keep the deformation of the solder and connectors connected to the external connection terminals 18 small, and it is difficult to prevent the solder and connectors from falling off the flexible sheet 16.

[0048] [Additional Form 4] FIG. 6 is a plan view of the sensor unit, showing examples of flexible sheets in the shapes of (A) a rectangle, (B) a pentagon, (C) an ellipse, (D) a trapezoid, and (E) an H-shape. Figure 7 is a plan view of a sensor unit, where (A) shows an example in which a single row of external connection terminals is aligned on a rectangular flexible sheet, (B) shows an example in which one and two rows of external connection terminals are aligned on a rectangular flexible sheet, and (C) shows an example in which a single row of external connection terminals is aligned on an H-shaped flexible sheet.

[0049] In basic form 1 or a form in which basic form 1 is combined with at least one of additional forms 2 and 3, the shape of the flexible sheet 16 is approximately rectangular with long sides along a direction perpendicular to the sheet surface reference line L1 and short sides along the direction of the sheet surface reference line L1, and the ratio Lmax / Wmax of the maximum dimension Lmax in the direction perpendicular to the sheet surface reference line L1 to the maximum dimension Wmax in the direction of the sheet surface reference line L1 is 3 or more and 30 or less, and at least two external connection terminals 18 are arranged, and the external connection terminals 18 are preferably aligned approximately parallel to the short sides (additional form 4).

[0050] Here, "substantially parallel to the short side" means that a direction within a range of ±5° with respect to the direction of the short side (the direction of the sheet surface reference line L1) is acceptable. Furthermore, "substantially rectangular" means that any shape that is roughly close to a rectangle is acceptable, and any shape such as that shown in any of Figures 6(A) to 6(E) is acceptable.

[0051] 6(A) to 6(E), the flexible sheet 16 has a shape in which the length in the direction perpendicular to the sheet surface reference line L1 is longer than the length in the direction of the sheet surface reference line L1. Among these, as shown in Fig. 6(A), when the shape of the flexible sheet 16 is a substantially rectangular shape having long sides along the direction perpendicular to the sheet surface reference line L1 and short sides along the direction of the sheet surface reference line L1, there is an advantage in that the manufacturing cost is low.

[0052] Furthermore, by setting the ratio Lmax / Wmax to 3 or more, the distance between the permanent magnet 12 and the magnetic sensor element 14 is not too close, excellent sensing sensitivity to bending deformation of the tire 20 is obtained, and it is possible to determine the deflection of the tire 20 with higher accuracy. Furthermore, by setting the ratio Lmax / Wmax to 3 or more, the dimension in the direction of the sheet surface reference line L1 (width Wmax in FIG. 7) is not too long, which prevents the flexible sheet 16 from falling off the tire 20 and ultimately increases the durability of the tire 20.

[0053] In contrast, by setting the ratio Lmax / Wmax to 30 or less, the dimension in the direction perpendicular to the sheet surface reference line L1 (width Lmax in FIG. 7) is not too long, which prevents the flexible sheet 16 from falling off the tire 20 and ultimately increases the durability of the tire 20. Furthermore, by setting the ratio Lmax / Wmax to 30 or less, the dimension in the direction of the sheet surface reference line L1 (width Wmax in FIG. 7) is not too short, which allows the sensor unit 10 to be manufactured without being restricted in terms of the placement of the external connection terminals 18.

[0054] From the above viewpoints, the ratio Lmax / Wmax is more preferably 4 or more and 29 or less, and most preferably 5 or more and 27 or less.

[0055] [Additional Form 5] 8 is a plan view of a sensor unit showing the relationship between the width V at the position of the sheet surface reference line L1 and the maximum width dimension Vmax in the direction of the sheet surface reference line L1. In Basic Configuration 1 or a configuration in which at least one of Additional Configurations 2 to 4 is added to Basic Configuration 1, it is preferable that the ratio V / Vmax of the width V at the position of the sheet surface reference line L1 to the maximum width Vmax in the direction of the sheet surface reference line L1 for flexible sheet 16 is 0.20 or more and 0.95 or less (Additional Configuration 5).

[0056] 8, the portion of the flexible sheet 16 where the permanent magnets 12 are arranged includes the sheet surface reference line L1, and is therefore likely to be the portion where the change in curvature is most drastic (in the direction perpendicular to the sheet surface reference line L1) when bending deformation occurs in the tire 20. For this reason, the portion of the flexible sheet 16 where the permanent magnets 12 are arranged should be particularly devised to prevent them from falling off the tire 20; in other words, it is preferable to make this portion as narrow as possible, and for example, it is preferable to ensure a certain degree of dimension in the direction of the sheet surface reference line L1.

[0057] From this perspective, by setting the ratio V / Vmax to 0.20 or more, not only can it be prevented that the flexible sheet 16 breaks when a force that stretches the flexible sheet 16 in a direction perpendicular to the sheet surface reference line L1 is applied to the flexible sheet 16 due to the width V being too narrow, but it can also be prevented that the adhesiveness of the flexible sheet 16 to the tire cavity surface deteriorates due to increased distortion of the end portion of the flexible sheet 16 due to the width Vmax being too wide. Note that, from the viewpoint of ensuring adhesiveness between the flexible sheet 16 and the permanent magnet 12, the width V of the flexible sheet 16 at the position of the sheet surface reference line L1 is preferably larger than the width of the permanent magnet 12 in the direction of the sheet surface reference line L1.

[0058] In contrast, by setting the ratio V / Vmax to 0.95 or less, it is possible to prevent areas of the flexible sheet 16 that are subject to large deformation from falling off from the tire cavity surface, and it is also possible to prevent the permanent magnet 12 from falling off from the flexible sheet.

[0059] From the above viewpoints, the ratio V / Vmax is more preferably 0.22 or more and 0.93 or less, and most preferably 0.25 or more and 0.90 or less.

[0060] [Additional Form 6] 9 is a diagram showing the state of adhesion of the flexible sheet on the tire cavity surface. Note that, for ease of explanation, the external connection terminals 18 are omitted from the figure. Also, only the area of ​​the tire 20 corresponding to the sensing area Rs shown in the figure is shown, but the surface of the tire 20 is usually larger than the surface on which the flexible sheet 16 is placed.

[0061] In Basic Form 1 or a form in which Basic Form 1 is combined with at least one of Additional Forms 2 to 5, when two lines that are parallel to the sheet surface reference line L1 in a plan view, include the magnetic sensor elements 14a, 14b, and 14c on the side of the sheet surface reference line L1, and pass through the ends of the magnetic sensor elements 14a, 14b, and 14c, and are respectively defined as sheet surface outer lines L2 and L3, and the area of ​​the flexible sheet that exists between the two sheet surface outer lines L2 and L3 is defined as sensing area Rs, it is preferable that 60% or more of the back surface of sensing area Rs be adhered to the tire 20 (Additional Form 6).

[0062] In the example shown in Figure 9, the magnetic sensor elements 14a and 14b are equidistant from the seat surface reference line L1, so both ends are on the seat surface outer line L2. However, if the distances from the seat surface reference line L1 to the magnetic sensor elements 14a and 14b are different, the magnetic sensor element (for example, 14a) that is farthest from the seat surface reference line L1 will be the magnetic sensor element that serves as the basis for determining the seat surface outer line L2.

[0063] Here, the sheet surface outer lines L2, L3 are set so that all the magnetic sensor elements (magnetic sensor elements 14a to 14c in FIG. 9) are included in the sensing region Rs on each side of the sheet reference line L1. In addition, in view of the excellent adhesion of the flexible sheet 16 to the tire 20, it is more preferable that the dimension of the flexible sheet 16 in the direction of the sheet surface reference line L1 be smaller than the dimension of the tire 20 in the direction of the sheet surface reference line L1.

[0064] Since 60% or more of the back surface of the sensing area Rs is adhered to the tire 20, when the tire 20 deforms, the flexible sheet 16 deforms in response to the deformation of the tire 20, allowing changes in magnetic flux density to be detected more accurately, and ultimately allowing the deflection of the tire 20 to be determined with even greater precision.

[0065] In this embodiment, it is more preferable that 80% or more of the back surface of the sensing region Rs is adhered to the tire 20, and it is extremely preferable that 100% of the back surface is adhered to the tire 20.

[0066] Furthermore, if another elastic body (e.g., a rubber layer) exists between the tire 20 and the flexible sheet 16 as a buffer material, the deformation behavior of the flexible sheet 16 may not accurately follow the deformation behavior of the tire 20. For this reason, it is preferable to place the flexible sheet 16 directly on the tire cavity surface. Specifically, it is preferable to place the flexible sheet directly on the inner liner that constitutes the tire cavity surface.

[0067] Furthermore, when the manufacturing process of the tire 20 includes a vulcanization process, the flexible sheet 16 may be disposed on the tire 20 before or after vulcanization. However, when the flexible sheet 16 is disposed on the tire 20 before vulcanization, the vulcanization is performed in a state where the permanent magnets 12, the magnetic sensor elements 14, the external connection terminals 18, etc. are not disposed on the flexible sheet 16.

[0068] [Additional Form 7] Figure 10 is a diagram showing the positional relationship between the permanent magnet and the magnetic sensor element before and after placing a flexible sheet (sensor unit) on the tire cavity surface, and shows an example in which the magnetization direction is parallel to the flexible sheet before placement.

[0069] In Basic Form 1 or a form in which Basic Form 1 is combined with at least one of Additional Forms 2 to 6, as shown in FIG. 10, when the flexible sheet 16 is not placed on the tire 20 (the diagram to the left of the arrow), it is preferable that the dimension Hc (mm) from the flexible sheet 16 to the highest point of the magnetic sensor element 14 and the distance d (mm) between the permanent magnet 12 and the magnetic sensor element 14 satisfy the following relationship (Additional Form 7). Hc≦30-120{cos(d / 50)―0.5)} 2 The distance d between the permanent magnet 12 and the magnetic sensor element 14 refers to the dimension between the center line of the permanent magnet 12 in the width direction and the center line of the magnetic sensor element 14 in the width direction, as shown in FIG.

[0070] In FIG. 10, when moving from the left side of the drawing to the right side, the tire 20 bends, causing the position of the magnetic sensor element 14 to change in the magnetic field generated by the permanent magnet 12, thereby changing the value of the sensed magnetic field strength. Furthermore, if the size of the magnetic sensor element 14 (for example, the aforementioned dimension Hc) is too large, the sensitivity of the signal to bending decreases, deteriorating the sensing accuracy. In this situation, the inventors discovered that even if the elastic body E bends in the same way, the position of the magnetic sensor element 14 in the magnetic field changes, so they introduced a function of d, and found that if the function satisfies the above range, good sensing sensitivity can be ensured.

[0071] [Additional Form 8] 11A and 11B are diagrams showing suitable examples (A) and (B) and an inappropriate example (C) of the position of the magnetic sensor element when a sensor unit is disposed on the surface of a tire. In Basic Mode 1 or a mode in which at least one of Additional Modes 2 to 7 is added to Basic Mode 1, as shown in Figs. 11A and 11B, in a state before bending deformation of the tire 20 in which the sensor unit 10 is disposed on the tire cavity surface, it is preferable that (the center of gravity of) the magnetic sensor element 14 is disposed on the center line Lc of the height of the permanent magnet 12 disposed on the concave curved surface of the tire 20 (Fig. 4A), or is disposed on the opposite side of the center line Lc from the surface on which the permanent magnet 12 is disposed (Fig. 4B) (Additional Mode 8).

[0072] In FIG. 11, the magnetic field lines generated by the permanent magnet 12 are as follows: The tire 20 is generally symmetrical with respect to the center line Lc because the tire 20 is made up of a high proportion of non-magnetic materials. When sensing the bending deformation behavior of the tire 20 based on changes in magnetic flux density, it is important to position the magnetic sensor element 14 so that it detects only the magnetic field on the same side of the center line Lc before and after bending deformation of the tire 20, in order to accurately detect changes in magnetic flux density.

[0073] The sensor unit 10 of the present application determines the behavior of bending deformation, i.e., deflection, based on, for example, the difference (amount of change) in magnetic flux density detected by the magnetic sensor element 14 before and after bending deformation of the tire 20. In the example shown in FIG. 11(A) (an example in which the magnetic sensor element 14 is disposed on the center line Lc before deformation of the tire 20) and the example shown in FIG. 11(B) (an example in which the magnetic sensor element 14 is disposed on the opposite side of the center line Lc from the arrangement surface of the permanent magnet 12 before deformation of the tire 20), when bending deformation occurs from the state before bending deformation shown in the figure, the magnetic sensor element 14 moves above the center line Lc. Therefore, because the magnetic sensor element 14 is located on only one side of the center line Lc before and after bending deformation, changes in magnetic flux density can be accurately detected, and ultimately, deflection of the tire 20 can be determined with even higher accuracy.

[0074] 11(c) (an example in which the magnetic sensor element 14 is disposed on the same side of the center line Lc as the arrangement surface of the permanent magnet 12 before deformation of the tire 20), when bending deformation occurs from the state before bending deformation shown in the figure, the magnetic sensor element 14 may move beyond the center line Lc. For this reason, it is conceivable that the magnetic sensor element 14 may be located on both sides of the center line Lc before and after bending deformation, and there may be cases in which a change in magnetic flux density cannot be accurately detected.

[0075] [Additional Form 9] In Basic Form 1 or a form in which Basic Form 1 is combined with at least one of Additional Forms 2 to 8, it is preferable that the above-mentioned flexible sheet 16 is a flexible substrate, the sensor unit 10 has electrical wiring EW (Figure 3) made of a conductor, and the magnetic sensor element 14 is mounted so as to be connected to the electrical wiring EW (Additional Form 9).

[0076] By using a flexible substrate for the flexible sheet 16, the flexible sheet 16 can better follow the deformation of the tire 20, thereby further increasing the durability of the tire 20. Although a flexible film can be interposed between the tire 20 and the flexible sheet 16, using the flexible sheet 16 itself as a flexible substrate can suppress a decrease in sensing sensitivity due to differences in deformation behavior between the layers, and ultimately enables the deflection of the tire 20 to be determined with even higher accuracy.

[0077] In this embodiment, the electric wiring EW refers to wiring that supplies power to the magnetic sensor element 14 and wiring that transmits signals by connecting to the output side of the magnetic sensor element 14. In this embodiment, the flexible substrate preferably includes at least one layer of highly non-elastic polyimide, and copper having low resistance is preferably used as the conductor.

[0078] [Additional Form 10] 12 is a meridian cross-sectional view of a part of the tire of this embodiment. The tire 20 shown in the drawing is mounted on a regular rim R and is in a no-load state (non-contact state) with a regular internal pressure.

[0079] In Basic Form 1 or a form in which Basic Form 1 is combined with at least one of Additional Forms 2 to 9, it is preferable that the sheet surface reference line L1 extends along the tire circumferential direction (the direction penetrating the paper surface) as shown in FIG. 12 (Additional Form 10).

[0080] Here, the sheet surface reference line L1 being along the tire circumferential direction means that the extension direction of the sheet surface reference line L1 is allowed to be shifted by 10° on each side along the surface of the flexible sheet 16 relative to the tire circumferential direction.

[0081] Considering that when the tire rolls on the ground, the tire exhibits substantially the same bending deformation behavior at any circumferential position, by extending the sheet surface reference line L1 (the line that is most likely to become the axis of bending deformation) along the tire circumferential direction in this manner, it is possible to achieve a high level of sensitivity in sensing the bending deformation of the tire 20, and ultimately to determine the deflection of the tire 20 with even greater accuracy.

[0082] As shown in FIG. 12, by forming a sensor unit 10 on the tire cavity surface of a tire 20, the sensor unit 10 having a permanent magnet 12, two magnetic sensor elements 14a, 14b, and two external connection terminals 18a, 18b formed on a flexible sheet 16, there is no need to embed the permanent magnet 12, the magnetic sensor elements 14a, 14b, and the external connection terminals 18a, 18b in the tire cavity surface, and a tire with a sensor unit can be easily manufactured.

[0083] [Additional Form 11] 13 is a diagram showing a circle passing through the centers of gravity of the permanent magnet and two magnetic sensor elements that constitute the sensor unit. In Basic Configuration 1 or a configuration in which at least one of Additional Configurations 2 to 10 is added to Basic Configuration 1, it is preferable that the radius r of a circle passing through three points, namely, the center of gravity of one magnetic sensor element 14a among the magnetic sensor elements arranged on one side of the seat surface reference line L1 in the above-mentioned concave circle C, the center of gravity of one magnetic sensor element 14b among the magnetic sensor elements arranged on the other side of the seat surface reference line L1 in the concave circle, and the center of gravity G of the permanent magnet 12, is 20 mm or more and 120 mm or less (Additional Configuration 11).

[0084] Here, the circle passing through the above three points means a circle in a no-load state (non-contact state) when the tire 20 is mounted on a rim and given a normal internal pressure.

[0085] By making the radius r of the circle 20 mm or more, bending deformation can be detected over a wider area with respect to the region between the two magnetic sensor elements 14a, 14b of the tire 20 in the tire meridian cross section, thereby further increasing the sensitivity for sensing bending deformation of the tire 20 and ultimately enabling the deflection of the tire 20 to be determined with even higher accuracy.

[0086] Furthermore, when the strength of the magnetic field (i.e., magnetic flux density) at positions equidistant from each pole of the permanent magnet 12 is taken into consideration, the magnetic flux density is highest on an extension of the magnetization direction, and decreases as the distance from the magnetization direction increases. Therefore, if the radius r of the circle is less than 20 mm, the position of the magnetic sensor element 14 may approach a direction perpendicular to the magnetization direction when the tire 20 flexes, which may weaken the detected magnetic field.

[0087] Furthermore, by setting the radius r of the circle to 120 mm or less, it is possible to ensure sufficient change in the radius of curvature of the concave curved surface of the tire 20 before and after bending deformation of the tire 20, and it is possible to prevent the dynamic range (the ratio between the minimum and maximum values ​​of the identifiable signal) of the signal output from the magnetic sensor element 14 from becoming too small.As a result, it is possible to further increase the sensitivity in sensing the bending deformation of the tire 20, and ultimately to determine the deflection of the tire 20 with even higher accuracy.

[0088] The radius r (see FIG. 13) is more preferably 22 mm or more and 118 mm or less, and most preferably 25 mm or more and 115 mm or less.

[0089] The two magnetic sensor elements 14a and 14b used to define the radius r in this embodiment are the magnetic sensor element 14a, which is one of the magnetic sensor elements arranged on one side of the sheet surface reference line L1, and the magnetic sensor element 14b, which is one of the magnetic sensor elements arranged on the other side within the concave circle C in Fig. 2. In this embodiment, in addition to these magnetic sensor elements 14a and 14b, magnetic sensor elements that are not used to define the radius r in this embodiment may be arranged.

[0090] [Additional Form 12] 14A and 14B are meridian cross-sectional views of a tire showing the position of a reference line on the tire cavity surface, and (A) shows an example in which not only the reference line but also the magnetic sensor element on the inner side in the tire width direction is located within a predetermined range, while (B) shows an example in which the magnetic sensor element on the inner side in the tire width direction is not located within the predetermined range. In both (A) and (B), the tire 20 shown in the figure is mounted on a regular rim R and pressurized to the regular internal pressure, in an unloaded state (non-contact state).

[0091] In the basic configuration 1 or a configuration in which at least one of additional configurations 2 to 11 is added to the basic configuration 1, as shown in FIG. 14, a belt 22 consisting of at least one belt layer 22a, 22b (two belt layers in the figure) is provided on the tire radially outer side of a carcass (not shown), and when the foot of a perpendicular line drawn from the tire width direction end of the belt layer 22a of the belt layers 22a, 22b that has the largest dimension in the tire width direction to the tire cavity surface is defined as a first point P1, and the outermost point in the tire radial direction among the feet of perpendicular lines drawn from each outer peripheral point of the bead core 24 to the tire cavity surface is defined as a second point P2, it is preferable that a reference line L0 obtained by projecting the sheet surface reference line L1 onto the tire cavity surface exists between the first point P1 and the second point P2 along the tire cavity surface (additional configuration 12).

[0092] By locating the reference line L0, which is the projection of the sheet surface reference line L1 onto the tire cavity surface, between the first point P1 and the second point P2 along the tire cavity surface, the portion of the tire close to the magnetic sensor elements 14a, 14b that straddles the sheet surface reference line L1 becomes a portion that is subject to very large deformation, thereby further increasing the sensitivity in sensing the bending deformation of the tire 20, and ultimately enabling the deflection of the tire 20 to be determined with even higher accuracy.

[0093] If the permanent magnet 12 is placed too close to the belt layers 22a, 22b containing steel cords, the steel cords may bias the distribution of magnetic field lines generated by the permanent magnet 12 in a specific direction, which may weaken the magnetic field received by the magnetic sensor elements 14a, 14b. Also, if the permanent magnet 12 is placed too close to the tire equatorial plane, the permanent magnet 12 may be deteriorated and demagnetized due to the influence of heat generated in the tread. In consideration of such undesirable situations, the position of the reference line L0 based on the sheet surface reference line L1 defined in this embodiment is set within the predetermined range as described above.

[0094] In addition, in Figure 14, (A) is an example in which not only the reference line L0 but also the magnetic sensor element 14a on the inner side in the tire width direction is located within the above-mentioned specified range of the tire cavity surface (between the first point P1 and the second point P2), while (B) is an example in which the magnetic sensor element 14a on the inner side in the tire width direction is not located within the above-mentioned specified range of the tire cavity surface, but the present embodiment is intended to include both the cases of Figure 14 (A) and (B) within the scope of the invention.

[0095] [Additional Form 13] 15 is a meridian cross-sectional view of a tire showing the position of a reference line on the tire cavity surface and the position of an end portion of a flexible sheet on the tread surface and closer to a point on the tire equatorial plane. The tire 20 shown in the figure is mounted on a regular rim R and is in a no-load state (non-contact state) with a regular internal pressure applied.

[0096] In a configuration in which Basic Configuration 1 or Basic Configuration 1 is combined with at least one of Additional Configurations 2 to 12, as shown in Fig. 15, a belt 22 consisting of at least one belt layer 22a, 22b (two belt layers in the figure) is provided on the radially outer side of a carcass (not shown), and a first point P1 is defined as the foot of a perpendicular line extending from the tire widthwise end of the belt layer 22a, 22b, which has the largest dimension in the tire width direction, to the tire cavity surface. Also, a third point P3 is defined as the maximum width position of the tire cavity surface. A reference line L0 obtained by projecting the sheet surface reference line L1 onto the tire cavity surface is located between the first point P1 and the third point P3 along the tire cavity surface. The end of the flexible sheet 16, which is on the tread surface and closer to a point on the tire equatorial plane, is preferably located inward in the tire width direction from the first point P1 (Additional Configuration 13). In Fig. 15, the symbol EW denotes electrical wiring.

[0097] By locating the reference line L0, which is the projection of the sheet surface reference line L1 onto the tire cavity surface, between the first point P1 and the third point P3 along the tire cavity surface, the portion of the tire close to the magnetic sensor elements 14a, 14b that straddles the sheet surface reference line L1 becomes a portion that is subject to very large deformation, thereby further increasing the sensitivity in sensing the bending deformation of the tire 20, and ultimately enabling the deflection of the tire 20 to be determined with even higher accuracy.

[0098] Furthermore, by positioning the end of the flexible sheet 16 on the tread surface and closer to a point on the tire equatorial plane more inward in the tire width direction than the first point P1, this end can be placed on the tire cavity surface of the tread portion, which has a significantly higher hardness than the sidewall portion. This makes it possible to maintain a stronger bond between the tire 20 and the inner portion (the end) of the sensor unit 10 in the tire width direction in particular. As a result, the end can be stably formed as a connection portion for electrical wiring and a connector connected to the sensor unit 10, and ultimately the durability of the tire 20 can be improved.

[0099] [Additional Form 14] In the basic configuration 1 or a configuration in which at least one of additional configurations 2 to 13 is added to the basic configuration 1, as shown in Fig. 14(B), a belt 22 consisting of at least one belt layer (two belt layers 22a and 22b in Fig. 14(B)) is provided on the tire radially outer side of the carcass, and when the foot of a perpendicular line drawn from the tire width direction end of the belt layer 22a of the belt layers 22a, 22b that has the largest dimension in the tire width direction to the tire cavity surface is defined as a first point P1, it is preferable that the length Ls along the tire cavity surface from the first point P1 to the end of the flexible sheet 16 on the tread surface and farther from a point on the tire equatorial plane is 10 mm or more and 35 mm or less (additional configuration 14). Note that in this embodiment, the tire 20 is mounted on a normal rim R and is in a no-load state (non-contact state) with normal internal pressure applied.

[0100] By making the length Ls 10 mm or more, the distance between the permanent magnet 12 and the magnetic sensor element 14 can be sufficiently secured, and bending deformation of the tire 20 can be detected over a wider range. As a result, the sensitivity for sensing bending deformation of the tire 20 can be further improved, and ultimately the deflection of the tire 20 can be determined with even higher accuracy.

[0101] In contrast, by setting the length Ls to 35 mm or less, the flexible sheet 16 can sufficiently follow the bending of the tire 20 when the tire 20 is bent and deformed, further preventing the sensor unit 10 from falling off the tire 20, and ultimately further increasing the durability of the tire 20.

[0102] From the above viewpoint, it is more preferable that the length Ls is 12 mm or more and 33 mm or less, and it is extremely preferable that the length Ls is 15 mm or more and 30 mm or less.

[0103] [Additional Form 15] 16A and 16B are diagrams showing the positional relationship between the permanent magnet, the magnetic sensor element, and the belt, where (A) shows the positional relationship between the magnetic sensor element and the belt, and (B) shows the positional relationship between the permanent magnet and the magnetic sensor element. The tire 20 shown in Fig. 15A is mounted on a regular rim R and is in a no-load state (non-ground-contact state) with the regular internal pressure applied.

[0104] In Basic Configuration 1 or a configuration in which Basic Configuration 1 is combined with at least one of Additional Configurations 2 to 14, as shown in FIG. 16, a belt 22 consisting of at least one belt layer 22a, 22b is provided on the tire radial outside of a carcass (not shown), and it is preferable that the distance t from the tire widthwise end of the belt layer 22a, 22b having the largest dimension in the tire widthwise direction among the belt layers 22a, 22b, to the innermost magnetic sensor element 14a arranged on the innermost side in the tire widthwise direction, and the distance d along the flexible sheet 16 from the magnetic sensor element 14a to the permanent magnet 12 satisfy d / t≦1.8 (Additional Configuration 15).

[0105] In this embodiment, the distance t and the distance d satisfy d / t≦1.8, thereby preventing the distance t between the magnetic sensor element 14a and the belt (specifically, the belt cord) from being excessively small relative to the distance d between the permanent magnet 12 and the magnetic sensor element 14a. This prevents magnetic field disturbance (deflection in a specific direction) around the magnetic sensor element 14a, which is relatively close to the belt cord, and allows the magnetic sensor element 14a to accurately measure the original magnetic flux density. Therefore, according to this embodiment, the sensitivity for sensing bending deformation of the tire 20 can be further improved, and ultimately the deflection of the tire 20 can be determined with even higher accuracy.

[0106] In this embodiment, the distance t between the magnetic sensor element 14a located at the innermost side in the tire width direction and the belt cord is set to 3.5% or more of the tire cross-sectional height, thereby enabling the original magnetic flux density to be measured at an extremely high level.

[0107] Furthermore, in this embodiment, by setting the distance d along the flexible sheet 16 from the magnetic sensor element 14a located at the innermost position in the tire width direction to the permanent magnet 12 to be 4% or more and 20% or less of the tire cross-sectional height, it is possible to further increase the sensitivity for sensing the bending deformation of the tire 20 when the actual curvature of the tire cavity surface and the actual position of the sensor unit 10 are taken into consideration, and therefore it is possible to determine the deflection of the tire 20 with even higher accuracy.

[0108] [Additional Form 16] FIG. 17 is a diagram showing the relationship between the seat surface reference line and the three directions of the permanent magnet. For ease of explanation, the magnetic sensor element 14 and the external connection terminal 18 are omitted from the diagram. Also, in the diagram, the symbol Dm indicates the magnetization direction. In Basic Configuration 1 or a configuration in which at least one of Additional Configurations 2 to 15 is added to Basic Configuration 1, as shown in FIG. 17, it is preferable that the permanent magnet 12 has the smallest dimension T (Additional Configuration 16) among the dimension H in the height direction, which is the direction of the perpendicular line from the center of gravity G to the concave curved surface of the tire 20, the dimension W in the direction of the seat surface reference line L1, and the dimension T in the direction perpendicular to both the height direction and the direction of the seat surface reference line L1.

[0109] By making the dimension T as small as possible, the permanent magnet 12 can suitably follow the deformation behavior of the tire 20 when the tire 20 undergoes bending deformation, and the adhesion state of the sensor unit 10, including the permanent magnet 12, to the tire 20 can be maintained even better over the long term, resulting in even greater durability of the tire 20.

[0110] For example, as shown in Fig. 17, when the permanent magnet 12 is magnetized in the height direction, the larger the product of the dimension W and the dimension T and / or the dimension H, the wider the magnetic field formed around the permanent magnet 12. For this reason, it is preferable to increase the dimension W and / or the dimension H by the amount that the dimension T is reduced. However, with regard to which of the dimension W and the dimension H should be increased first, it is preferable to increase the dimension H first over the dimension W from the viewpoint of maintaining a good adhesion state of the sensor unit 10, including the permanent magnet 12, to the tire 20 for a long period of time.

[0111] The preferable relationship between the dimensions T, W, and H is summarized as follows: dimension T≦dimension W≦dimension H, and the effect of these relationships is particularly pronounced when the permanent magnet 12 is a rectangular parallelepiped.

[0112] Furthermore, the dimension T is more preferably 1.0 mm or more and 5.0 mm or less, even more preferably 1.2 mm or more and 4.8 mm or less, and extremely preferably 1.5 mm or more and 4.5 mm or less. The dimension W is more preferably 1.5 mm or more and 10.0 mm or less, even more preferably 1.7 mm or more and 9.8 mm or less, and extremely preferably 2.0 mm or more and 9.5 mm or less. The dimension H is more preferably 2.0 mm or more and 15.0 mm or less, even more preferably 2.5 mm or more and 14.0 mm or less, and extremely preferably 3.0 mm or more and 13.0 mm or less.

[0113] Furthermore, with regard to the permanent magnet 12, it is more preferable that the maximum value of the magnetic flux density on the surface be 50 mT or more and 900 mT or less. By setting this maximum value to 50 mT or more, even if the magnetization direction of the permanent magnet 12 is the direction shown in FIG. 17, the distance between the two magnetic sensor elements 14a, 14b will not be too close, and a wider bending deformation range and therefore sufficient sensing sensitivity will be obtained. On the other hand, by setting this maximum value to 900 mT or less, the magnetic force of the permanent magnet 12 will not be excessive, and there will be no risk of metal foreign objects such as nails being attracted to the surface of the tire 20 on which the sensor unit 10 including the permanent magnet 12 is disposed, thereby preventing accidental damage to the tire 20. It is more preferable that this maximum value be 60 mT or more and 890 mT, and extremely preferable that it be 100 mT or more and 850 mT.

[0114] As the permanent magnet 12 as a component of the sensor unit 10 of the present application, a unipolar magnetized sintered magnet can be used, such as a ferrite magnet or a neodymium magnet. In the example shown in Fig. 17, the magnetization direction Dm is in the direction of dimension H, but the magnetization direction is not limited to this and can also be in the direction of dimension T.

[0115] [Additional Form 17] Fig. 18 is a meridian cross-sectional view of a tire showing the relationship between the dimensions of a permanent magnet and tire thickness. In Basic Mode 1 or a mode in which at least one of Additional Modes 2 to 16 is added to Basic Mode 1, as shown in Fig. 18, the dimension T of the permanent magnet 12 in a direction perpendicular to both the sheet surface reference line L1 (a line extending substantially in the tire circumferential direction, i.e., a line extending in a direction penetrating the page) and the perpendicular line from the center of gravity G of the permanent magnet 12 to the tire cavity surface is preferably 0.10 to 0.75 times the tire thickness Ga on the perpendicular line from the center of gravity G of the permanent magnet to the tire cavity surface (Additional Mode 17).

[0116] By making the dimension T 0.10 times or more the tire thickness Ga, the magnetic force of the permanent magnet 12 can be further increased, thereby further increasing the sensitivity for sensing the bending deformation of the tire 20 and enabling the deflection of the tire 20 to be determined with even higher accuracy.

[0117] In contrast, by setting the dimension T to 0.75 times the tire thickness Ga or less, the adhesion state between the permanent magnets 12 and the flexible sheet 16 is maintained well during bending deformation of the tire, and the permanent magnets 12 are prevented from falling off or being damaged from the flexible sheet 16, thereby further improving the durability of the tire 20.

[0118] From this viewpoint, it is more preferable that the dimension T be 0.12 times or more and 0.73 times or less, and it is extremely preferable that the dimension T be 0.15 times or more and 0.70 times or less, of the tire thickness Ga.

[0119] [Additional Form 18] In Basic Form 1 or a form in which Basic Form 1 is combined with at least one of Additional Forms 2 to 17, when the contour of the flexible sheet 16 is projected onto the carcass layer, it is preferable that the number of carcass cords that intersect with the projected sheet surface reference line L1 across the projected width of the flexible sheet 16 (hereinafter referred to as the "number of intersecting cords") is 2 or more and 15 or less (Additional Form 15).

[0120] Here, the projected width of the flexible sheet 16 refers to the maximum dimension of the flexible sheet 16 projected onto the carcass layer in the direction of the sheet surface reference line L1. Furthermore, if the carcass is composed of multiple carcass layers, the number of cross cords refers to the number of carcass cords in the carcass layer that is the innermost layer of the tire (closest to the tire cavity surface).

[0121] 18, all or most of the flexible sheet 16 is disposed in the tire width direction region where no belt layer is present. Therefore, how the flexible sheet 16 deforms due to deformation caused by the tire contacting the ground depends greatly on the deformation of the carcass cords, because the tensile modulus of elasticity of the carcass cords is much greater than that of rubber.

[0122] If the circumferential width of the flexible sheet 16 is less than two carcass cords (i.e., if the number of cross cords is less than two), the adhesive surface of the flexible sheet 16 to the inner liner is strongly affected by the movement of the carcass cords included in the projection range of the flexible sheet 16 onto the carcass layer.

[0123] Specifically, due to the symmetry of the tire, the normal vector of the flexible sheet 16 passing through the center of gravity of the permanent magnet 12 should be contained within the meridian section of the tire that includes the center of gravity of the permanent magnet 12 at the tire circumferential center position of the tire. However, at the tire circumferential end portions, the normal vector of the flexible sheet 16 may deviate from the meridian section. This is because the face width (dimension in the tire circumferential direction) of the flexible sheet 16 is so small that it cannot absorb the movement of the carcass cords averaged in the tire circumferential direction.

[0124] This phenomenon can cause the permanent magnet 12, which stands vertically toward the tire cavity, to tilt in the circumferential direction of the tire when the tire is rolling, resulting in a so-called rocking motion, which can ultimately cause a decrease in sensing accuracy.

[0125] On the other hand, when the surface width of the flexible sheet 16 exceeds 15 carcass cords (i.e., when the number of cross cords exceeds 15), there is no problem in that the adhesive surface of the flexible sheet 16 to the inner liner can absorb the movement of the carcass cords evenly in the circumferential direction of the tire.

[0126] However, in this case, the width of the flexible sheet 16, which exceeds the width of 15 carcass cords, is too large in the circumferential direction of the tire, and therefore, as the flexible sheet 16 moves from the non-ground contact area to the ground contact area during tire rolling, the distance between the carcass cords increases in the ground contact area and its vicinity, while the distance between the carcass cords has not yet increased in areas far from the ground contact area, resulting in a situation in which the deformation behavior of the carcass varies locally in the circumferential direction of the tire.

[0127] As a result, the in-plane stress acting on the flexible sheet 16 becomes non-uniform in the tire circumferential direction. Here, since the flexible sheet 16 is less stretchable (has a higher elastic modulus) than the tire constituent members (carcass, inner liner, etc.), it cannot follow the expansion between the carcass cords (i.e., the expansion of the carcass rubber following the expansion of the carcass cords). As a result, the adhesive surface between the tire cavity surface and the flexible sheet 16 is subjected to the aforementioned local stress changes in the tire circumferential direction, resulting in a decrease in the durability of the adhesive of the flexible sheet 16.

[0128] From this viewpoint, the number of crossing cords is more preferably 3 or more and 14 or less, and most preferably 4 or more and 12 or less.

[0129] [Other tire types] Further preferred examples of the tire 20 equipped with the sensor unit 10 described above will be described below.

[0130] (Suitable example 1) It is preferable that two to ten of the above-described sensor units 10 are arranged in the tire circumferential direction on the tire cavity surface. When determining the state of tire deformation for the purpose of vehicle attitude control while the tire is rolling, obtaining data for determining the state of deformation at different points in the tire circumferential direction is advantageous for comprehensively determining the deformation of the entire tire. However, even if eleven or more sensor units 10 are arranged in the tire circumferential direction, the effect of determining the state of tire deformation more accurately in proportion to the number of sensor units 10 arranged is not sufficiently obtained, so the preferred number of sensor units 10 to be arranged is ten or less.

[0131] In addition, when multiple sensor units 10 are arranged in the tire circumferential direction, it is highly preferable to arrange the multiple sensor units 10 at equal intervals in the tire circumferential direction, since detecting the deformation state of the tire 20 evenly in the tire circumferential direction is effective in efficiently determining the deformation state of the entire tire.

[0132] (Preferable example 2) Figure 19 is a meridian cross section of a tire showing suitable positions for placing a circuit board connected to a sensor unit, where (A) shows an example in which the circuit board is placed closer to the center of the tread than an area where it is undesirable to place it, and (B) shows an example in which the circuit board is placed closer to the bead than an area where it is undesirable to place it.

[0133] The circuit board 30a shown in FIG. 19(A) and the circuit board 30b shown in FIG. 18(B) include an amplifier circuit, a power supply circuit, a signal processing circuit, a communication circuit, and the like.

[0134] In the example shown in Figures 19(A) and 19(B), if the foot of a perpendicular line drawn from the tire width direction end of the belt layer 22a with the largest dimension in the tire width direction to the tire cavity surface is defined as a first point P1 and the maximum width position of the tire cavity surface is defined as a third point P3, both of the circuit boards 30a and 30b are arranged in areas with relatively small bending deformation along the tire cavity surface other than the area between the first point P1 and the third point P3.

[0135] In this way, by arranging the circuit board 30 (30a, 30b) in an area that experiences relatively little bending deformation during tire deformation, it is possible to suppress the circuit board 30 from falling off from the tire cavity surface during bending deformation of the tire 20, thereby further increasing the durability of the tire 20.

[0136] (Suitable example 3) 20 is a plan view showing the positions of the magnetic sensor elements in the sensor unit, where (A) shows an example in which two magnetic sensor elements are arranged in a predetermined area, (B) shows an example in which two magnetic sensor elements are arranged in an area other than the predetermined area in the example shown in (A), (C) shows an example in which three magnetic sensor elements are arranged in a predetermined area, and (D) shows an example in which four magnetic sensor elements are arranged in a predetermined area. Note that in Fig. 19, the N and S poles of the permanent magnet 12 are provisionally depicted, but a type in which these are reversed is also included in the scope of this preferred example.

[0137] As shown in Figure 20, in a plan view of the sensor unit 10, it is preferable that the magnetic sensor element 14 is formed in an area (predetermined area) 45° on either side of the sheet surface reference line L1, the area being 45° from both sides of a straight line L that passes through the midpoint of the permanent magnet 12 in the direction of the sheet surface reference line L1 and extends in the magnetization direction Dm.

[0138] Such a predetermined region has a higher magnetic flux density than other regions, and by placing the magnetic sensor elements 14 (14a to 14d) in that region, the sensitivity in sensing the bending deformation of the tire 20 can be further increased, and ultimately the deflection of the tire 20 can be determined with even higher accuracy.

[0139] In Figure 20, it is more preferable that the magnetic sensor element 14 is formed in an area of ​​40 degrees on either side of the sheet surface reference line L1, and it is extremely preferable that it is formed in an area of ​​35 degrees on both sides of a line L that passes through the midpoint of the permanent magnet 12 in the direction of the sheet surface reference line L1 and extends in the magnetization direction Dm.

[0140] 20, it is preferable that the magnetization direction Dm forms an angle of 80° to 100° with respect to the sheet surface reference line L1 (in other words, an angle of 10° or less on either side of the line L). When the shape of the tire cavity surface and the bending deformation behavior of the tire are taken into consideration, the flexible sheet 16 is usually arranged in the tire 20 so that the sheet surface reference line L1 shown in FIG. 20 is aligned along the tire circumferential direction and so that the vertical direction shown in the same figure is aligned roughly along the tire radial direction. In such a case, by setting the magnetization direction Dm to a direction extending at an angle of 80° to 100° with respect to the sheet surface reference line L1, it is possible to ensure a relatively wide predetermined area, and further widen the selectable area for the positions of the magnetic sensor elements 14a, 14b.

[0141] The magnetization direction Dm is more preferably set to a direction extending at an angle of 82° to 98° with respect to the sheet surface reference line L1, and most preferably set to a direction extending at an angle of 85° to 95°. [Example]

[0142] Below, we will compare the effects of the tire inventions defined in claims 1 to 18 of the present application (hereinafter referred to as "Invention Examples 1 to 18") with an invention similar to the invention described in Patent Document 1 (hereinafter referred to as "Prior Art Example").

[0143] The tire size was 245 / 40R19 (specified by JATMA), and each of the tires of Examples 1 to 18 of the invention was mounted on a rim as shown in Fig. 15. The tires were subjected to bending deformation from a no-load state (before deformation) with normal internal pressure applied to a state (after deformation) with 80% of the normal load applied. The rate of change in the difference between the outputs of the two magnetic sensor elements 14a and 14b before and after tire deformation was calculated. The rim width of the wheel was 8.5 inches (215.9 mm).

[0144] In contrast, in the conventional example, since there was one magnetic sensor element, the rate of change in the output value of that one magnetic sensor element before and after tire deformation was calculated, and the other conditions were the same as those of each of the invention examples.

[0145] Then, for the tires of the conventional example and each of the inventive examples, this rate of change was converted to a value with the conventional example being set at 100, and used as an evaluation value (expressed as an index) indicating the tire deflection sensing sensitivity. A larger evaluation value indicates that the tire deflection can be determined with higher sensitivity. The tire conditions for the conventional example and inventive examples 1 to 18 are as shown in Table 1 below. In each example, a unipolar magnetized permanent magnet was used. The magnetization direction was parallel to the flexible sheet when the sensor unit was not placed on the tire (Figure 10). The rectangular flexible sheet shown in Figure 3(A) was used.

[0146] [Table 1]

[0147] In Table 1, the sheet surface reference line L1, Lmax, Wmax, V, Vmax, sensing area Rs, dimension Hc, radius r, reference line L0, length Ls, d / t, T / Ga, dimension H, dimension W, dimension T, number of intersecting cords, etc. conform to the definitions described in this specification.

[0148] Table 1 shows that all of the tires within the technical scope of the present invention have higher sensitivity to sensing tire flexure than conventional tires. [Explanation of symbols]

[0149] 10 Sensor Unit 12 Permanent magnets 14 (14a, 14b, 14c, 14d) Magnetic sensor element 16 Flexible sheet 18(18a~18p) External connection terminal 20 tires 22 Belt 22a, 22b belt layers 24 bead core 30a, 30b Circuit board C concave circle d Distance from the magnetic sensor element to the permanent magnet along the flexible sheet Dm Magnetization direction EW Electrical wiring G Center of gravity of permanent magnet Ga Tire Thickness H: The height dimension of the permanent magnet, which is the direction of the perpendicular line from the center of gravity to the tire cavity surface Hc: Dimension from the flexible sheet to the highest point of the magnetic sensor element L straight line L0 reference line L1 Sheet surface reference line L2, L3 Sheet surface outer line L41~L46 Lines parallel to the sheet surface reference line Lc Center line of permanent magnet placement height Ls: The length along the tire cavity surface from the first point to the end of the flexible sheet on the tread surface and closer to the point on the tire equatorial plane. P1 First point P2 Second point P3 Third Point R rim Rs sensing area r radius of the circle T: Dimension of a permanent magnet in the direction perpendicular to both the height direction and the direction of the reference line t is the distance from the end of the belt layer with the largest dimension in the tire width direction to the innermost magnetic sensor element W Dimension of the permanent magnet in the direction of the reference line

Claims

1. A tire having a sensor unit on a tire cavity surface for determining the deflection of the tire during bending deformation of the tire, the sensor unit includes a non-magnetic, non-stretchable flexible sheet, and one permanent magnet, at least two magnetic sensor elements, and at least one external connection terminal, which are formed on the flexible sheet; The deflection of the tire is determined by performing a calculation using signals output from each of the at least two magnetic sensor elements; determining a concave circle formed by projecting onto the tire surface a circle that is centered on the center of gravity of the permanent magnet, is included in a plane perpendicular to a straight line that includes a perpendicular line extending from the center of gravity to the tire surface, and has a radius that is the longest distance between this straight line and the magnetic sensor element; Next, when a line including the diameter of the concave circle with the largest radius of curvature is defined as a seat surface reference line, at least one magnetic sensor element is disposed in each of regions on one side and the other side of the seat surface reference line within the concave circle, The tire, wherein the at least one external connection terminal is disposed farther from the sheet surface reference line than the magnetic sensor element to which the external connection terminal is connected.

2. The tire according to claim 1 , wherein, in a plan view, the electrical wiring connecting the magnetic sensor element and the external connection terminal does not intersect with the sheet surface reference line.

3. The tire according to claim 1 or 2, wherein the plurality of external connection terminals are aligned at the end portions in the longitudinal direction on at least one side of the sheet surface reference line.

4. 3. The tire according to claim 1, wherein the flexible sheet has a shape that is substantially rectangular having long sides extending along a direction perpendicular to the sheet surface reference line and short sides extending along the direction of the sheet surface reference line, wherein a ratio Lmax / Wmax of a maximum dimension Lmax in the direction perpendicular to the sheet surface reference line to a maximum dimension Wmax in the direction of the sheet surface reference line is 3 or more and 30 or less, and wherein at least two external connection terminals are arranged and the external connection terminals are aligned substantially parallel to the short sides.

5. 3. The tire according to claim 1, wherein the flexible sheet has a width V at the position of the sheet surface reference line and a maximum width Vmax in the direction of the sheet surface reference line, the ratio V / Vmax being 0.20 or more and 0.95 or less.

6. In a plan view, when two lines that are parallel to the sheet surface reference line, include the magnetic sensor element on the sheet surface reference line side, and pass through an end of the magnetic sensor element are defined as sheet surface outer lines, and the area of ​​the flexible sheet that exists between the two sheet surface outer lines is defined as a sensing area, The tire according to claim 1 or 2, wherein 60% or more of the back surface of the sensing area is adhered to the tire.

7. 3. The sensor unit of claim 1, wherein when the flexible sheet is not placed on the elastic body, the dimension Hc from the flexible sheet to the highest point of the magnetic sensor element and the distance d (mm) between the permanent magnet and the magnetic sensor element satisfy the following relationship: Hc≦30-120{cos(d / 50)―0.5)} ２

8. In a state before the tire is bent and deformed, in which the sensor unit is disposed on the tire cavity surface, the magnetic sensor element is located on the concave curved surface of the flexible sheet. The permanent magnet is disposed on the center line of the height of the concave curved surface, or The permanent magnet is disposed on the opposite side of the center line from the surface on which the permanent magnet is disposed.

3. The tire according to claim 1 or 2.

9. the flexible sheet is a flexible substrate, The tire according to claim 1 or 2, further comprising an electric wiring made of a conductor, and the magnetic sensor element is mounted so as to be connected to the electric wiring.

10. The tire according to claim 1 or 2, wherein the sheet surface reference line extends along the tire circumferential direction.

11. 3. The tire according to claim 1, wherein a radius r of a circle passing through three points, namely, the center of gravity of one of the magnetic sensor elements arranged on one side of the sheet surface reference line within the concave circle, the center of gravity of one of the magnetic sensor elements arranged on the other side of the sheet surface reference line within the concave circle, and the center of gravity of the permanent magnet, is 20 mm or more and 120 mm or less.

12. In a tire meridian cross section, a belt having at least one belt layer is provided on an outer side of the carcass in the tire radial direction, When a foot of a perpendicular line extending from an end portion in the tire width direction of the belt layer having the largest dimension in the tire width direction among the belt layers to the tire cavity surface is defined as a first point, and a point on the outermost side in the tire radial direction among the feet of perpendicular lines extending from each outer peripheral point of the bead core to the tire cavity surface is defined as a second point, The tire according to claim 1 or 2, wherein a reference line obtained by projecting the sheet surface reference line onto a tire cavity surface exists between the first point and the second point along the tire cavity surface.

13. In a tire meridian cross section, a belt having at least one belt layer is provided on an outer side of the carcass in the tire radial direction, When a foot of a perpendicular line drawn from an end portion in the tire width direction of the belt layer having the largest dimension in the tire width direction among the belt layers to a tire cavity surface is defined as a first point, and a maximum width position on the tire cavity surface is defined as a third point, a reference line obtained by projecting the sheet surface reference line onto a tire cavity surface exists along the tire cavity surface between the first point and the third point, The tire according to claim 1 or 2, wherein an end of the flexible sheet on the tread surface and closer to a point on the tire equatorial plane is located more inward in the tire width direction than the first point.

14. In a tire meridian cross section, a belt having at least one belt layer is provided on an outer side of the carcass in the tire radial direction, When a foot of a perpendicular line extending from an end portion in the tire width direction of the belt layer having the largest dimension in the tire width direction among the belt layers to a tire cavity surface is defined as a first point, 3. The tire according to claim 1, wherein a length Ls along a tire cavity surface from the first point to an end of the flexible sheet on the tread surface and farther from a point on the tire equatorial plane is 10 mm or more and 35 mm or less.

15. a belt having at least one belt layer on the tire radial direction outer side of the carcass; 3. The tire according to claim 1, wherein a distance t from an end in the tire width direction of a belt layer that has a maximum dimension in the tire width direction among the belt layers to an innermost magnetic sensor element that is arranged on the innermost side in the tire width direction, and a distance d from the magnetic sensor element to the permanent magnet along the flexible sheet satisfy d / t≦1.

8.

16. Regarding the permanent magnet, A height dimension H, which is a direction of a perpendicular line from the center of gravity to the tire cavity surface; A dimension W in the direction of the sheet surface reference line; A dimension T in a direction perpendicular to both the height direction and the direction of the sheet surface reference line; The tire according to claim 1 or 2, wherein the dimension T is the smallest among the above.

17. 3. The tire according to claim 1, wherein a dimension of the permanent magnet in a direction perpendicular to both the sheet surface reference line and a perpendicular line from the center of gravity of the permanent magnet to the tire cavity surface is 0.10 to 0.75 times the tire thickness on the perpendicular line from the center of gravity of the permanent magnet to the tire cavity surface.

18. 3. The tire according to claim 1, wherein, when the contour of the flexible sheet is projected onto the carcass layer, the number of carcass cords that intersect with the projected sheet surface reference line across the projected width of the flexible sheet is 2 or more and 15 or less.

Images