Physical quantity detection device

Abstract

The present invention comprises: a strain detection element 6a; a base member 6b to which the strain detection element 6a is fixed; and a holding member 7 which holds therein the base member 6b and which has a bottom surface 7a that can be attached to an inner surface T1 of a tire T. The holding member 7 includes a hollow space 7i that is positioned, with respect to the strain detection element 6a, on the center direction-side of the tire T.

Description

[Technical field]

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

[0002] As a device for detecting physical quantities related to the condition of a tire (physical quantity detection device), Patent Document 1 discloses a functional component that includes an accommodation section for electronic components capable of acquiring information about the inside of the tire, a housing having a bottom surface facing the inner surface of the tire, a cylindrical portion (skirt) extending from the periphery of the bottom surface of the housing toward the inner surface of the tire, and a strain sensor attached to the bottom surface of the housing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-055402 A Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 describes that the housing is made of synthetic resin or the like, and the strain sensor is attached to the bottom surface of the housing (the tire inner peripheral surface side). Therefore, the deformation of the strain sensor due to the force acting from the road surface on which the tire is in contact toward the tire center is restricted by the housing, and there is a risk that the sensitivity of the strain sensor will decrease.

[0005] An object of the present invention is to provide a physical quantity detection device capable of detecting strain in a tire with high sensitivity. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the present invention comprises a strain detection element, a base member to which the strain detection element is fixed, and a retaining member that holds the base member inside and has a bottom surface that can be attached to the inner surface of a tire, the retaining member having a hollow space located toward the tire center relative to the strain detection element. Effect of the Invention

[0007] According to the present invention, it is possible to provide a physical quantity detection device capable of detecting the distortion of a tire with high sensitivity. Problems, configurations and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view of a tire to which a physical quantity detection device according to a first embodiment of the present invention is attached. [Diagram 2] 2 is a cross-sectional view of the physical quantity detection device of FIG. 1. [Diagram 3] FIG. 1 is a plan view of a strain sensor according to a first embodiment of the present invention. [Figure 4] 4 is a cross-sectional view taken along line AA in FIG. [Diagram 5] FIG. 2 is a front view of the holding member according to the first embodiment of the present invention. [Figure 6] FIG. 2 is a side view of the holding member according to the first embodiment of the present invention. [Figure 7] 1 is a cross-sectional view of a holding member to which a strain sensor is attached and fixed to an inner surface of a tire with an adhesive, according to a first embodiment of the present invention. [Figure 8] 5A to 5C are schematic cross-sectional views comparing the effects of the holding member according to the first embodiment of the present invention and a holding member according to a comparative example. [Figure 9] FIG. 11 is a front view of a holding member according to a second embodiment of the present invention. [Figure 10] FIG. 11 is a side view of a holding member according to a second embodiment of the present invention. [Figure 11] FIG. 11 is a front view of a holding member according to a third embodiment of the present invention. [Figure 12] FIG. 11 is a side view of a holding member according to a third embodiment of the present invention. [Figure 13] FIG. 11 is a front view of a holding member according to a fourth embodiment of the present invention. [Figure 14] FIG. 11 is a side view of a holding member according to a fourth embodiment of the present invention. [Figure 15] FIG. 11 is a cross-sectional view of a physical quantity detection device according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The configuration and operation of the physical quantity detection device according to the first to fifth embodiments of the present invention will be described below with reference to the drawings. In each drawing, the same reference numerals indicate the same parts. In addition, the cross-sectional view, front view, and side view each specify the direction by the mutually orthogonal XYZ axes, and +X is defined as "right", -X is "left", +Y is "up", -Y is "down", +Z is "front", and -Z is "rear".

[0010] (First embodiment) 1 is a cross-sectional view of a tire T equipped with a physical quantity detection device 1. As shown in FIG 1, the physical quantity detection device 1 is attached to an inner surface T1 of the tire T of a vehicle, and detects physical quantities including strain of the tire T.

[0011] The physical quantity detection device 1 is fixed to a surface (inner surface T1) of an inner liner formed on the inside of a tread portion T2 of a tire T, for example.

[0012] Fig. 2 is a cross-sectional view of the physical quantity detection device 1 of Fig. 1. As shown in Fig. 2, the physical quantity detection device 1 includes a housing case 2, a cover 3, a skirt 4, a circuit unit 5, a strain sensor 6, and a holding member 7, and is fixed to an inner surface T1 of a tire T with an adhesive 8.

[0013] The housing case 2 has, for example, a cylindrical shape with a bottom that opens upward (+Y direction), and houses the circuit unit 5. The housing case 2 is preferably made of, for example, a synthetic resin in order to ensure light weight and strength.

[0014] The cover 3 is a lid that closes the opening of the storage case 2 and covers the circuit section 5, and includes a disk section 3a and a protruding section 3b that extends downward (in the -Y direction) along the outer periphery of the disk section. Like the storage case 2, the cover 3 is preferably made of, for example, a synthetic resin in order to reduce weight and ensure strength.

[0015] The skirt 4 is a component that covers and protects the portion where the storage case 2 and the inner surface T1 of the tire T are joined, and absorbs vibrations of the inner surface T1 of the tire T, and is made of, for example, an elastic resin. The skirt 4 is provided with a cylindrical portion 4a that fits into the side peripheral surface of the lower portion of the storage case 2, and an enlarged portion 4b that extends downward (in the -Y direction) from the cylindrical portion 4a in a fan-like shape.

[0016] The circuit unit 5 is a component that detects physical quantities and transmits the detection results to the outside, and includes a circuit board 5a on which electronic components are mounted, a battery 5b that supplies electricity, and a wiring unit 5c that electrically connects the circuit board 5a and the battery 5b.

[0017] The circuit board 5a includes, for example, sensors for detecting temperature, air pressure, acceleration, etc., a transmitter for transmitting the detected values ​​of the sensors to the outside of the tire, and a controller for controlling them. The battery 5b is, for example, a button battery, which is fixed to the bottom of the housing case 2 and supplies electricity to the circuit board 5a via the wiring part 5c.

[0018] The strain sensor 6 is a component that detects strain and transmits the detected value to the circuit section 5. Fig. 3 is a plan view of the strain sensor 6, and Fig. 4 is a cross-sectional view taken along line AA in Fig. 3. As shown in Fig. 3, the strain sensor 6 includes a strain detection element 6a, a base member 6b, a sealing section 6c, and an electric wire section 6d.

[0019] The strain detection element 6a is a semiconductor that outputs the amount of strain according to a change in resistance, and is, for example, a semiconductor strain sensor in which a sensor element and a control circuit are integrated into a single chip.

[0020] The semiconductor strain sensor is an IC chip manufactured by a semiconductor process, and is, for example, a rectangular MOSFET type sensor chip with a size of about 5 mm x 5 mm. The semiconductor strain sensor is composed of, for example, a semiconductor formed by a CMOS process and a microelectromechanical system (MEMS). If the strain sensor is large, there is a risk of it being damaged when the tire runs over a foreign object, so it is preferable that the strain sensor is smaller than 5 mm x 5 mm. The strain detection element 6a is not limited to a semiconductor strain sensor, and for example, a strain gauge may be used.

[0021] The base member 6b is a member for fixing the strain detection element 6a, and is, for example, a thin metal plate with a linear expansion coefficient close to that of the semiconductor material (Si, etc.) forming the strain detection element 6a. As a metal with a linear expansion coefficient close to that of the semiconductor material (Si, etc.), for example, 42 Alloy (42 Alloy: an alloy of iron and nickel), which has a linear expansion coefficient of about 5 ppm / °C, which is about 1 ppm / °C different from that of silicon (Si), which is about 4 ppm / °C, can be used.

[0022] In this way, by using a metal having a linear expansion coefficient close to that of the semiconductor material as the material of the base member 6b, the strain detection accuracy of the strain detection element 6a can be improved.

[0023] The base member 6b is not limited to the above metals. For example, a metal having corrosion resistance against sulfur gas generated from the tire T (stainless steel, aluminum, copper, iron-based alloy, or a base metal plated with gold, nickel, tin, or the like) may be used.

[0024] The base member 6b is a rectangular thin plate so that the holding member 7 can be easily held and the strain of the tire can be accurately transmitted to the strain detection element 6a. Also, the end of the base member 6b in the +Z direction (front side) is arc-shaped as shown in Fig. 3 so that the base member 6b can be easily inserted into the holding member 7. Note that the shape of the base member 6b is not limited to the above, and it may be a circle, an ellipse, or another polygon.

[0025] The strain detection element 6a is fixed to the surface (+Z side surface) of the base member 6b by an adhesive, for example, an epoxy-based adhesive with high hardness.

[0026] The sealing portion 6c is a resin, such as an epoxy resin, applied to the surface of the base member 6b from above the strain detection element 6a and a bonding wire (not shown) that electrically connects the strain detection element 6a and the electric wire portion 6d. The strain detection element 6a and the bonding wire are sealed and protected from the external environment by the sealing portion 6c. Note that the sealing portion 6c is not limited to epoxy resin, and other resins, such as urethane resin and silicone resin, may be used.

[0027] The electric wire portion 6d is an electric wire that electrically connects the strain detection element 6a to the circuit portion 5, and is, for example, a flexible printed circuit (FPC).

[0028] The holding member 7 is a component that holds the base member 6b of the strain sensor 6 therein and has a bottom surface 7a that can be attached to the inner surface T1 of the tire T. In addition, the holding member 7 is preferably formed of, for example, cushion rubber having an elastic modulus that is approximately equal to or less than that of the tire T. An upper portion of the holding member 7 is fixed to a lower portion of the housing case 2 by, for example, an adhesive.

[0029] Fig. 5 is a front view of the holding member 7 according to the first embodiment of the present invention. Fig. 6 is a side view of the holding member 7 according to the first embodiment of the present invention. As shown in Figs. 5 and 6, the holding member 7 is a rectangular prism-shaped member that is long in the front-rear direction (Z-axis direction), and includes a holding part 7b that holds the base member 6b of the strain sensor 6, and legs 7g and 7h that support the base member 6b.

[0030] The holding portion 7b is a groove that is provided in the center of the holding member 7 in the left-right direction (X-axis direction), opens downward (-Y direction) of the holding member 7, and extends in the front-rear direction (Z-axis direction) of the holding member 7. The holding portion 7b is provided with a plurality of holding grooves 7cd each having a first groove 7c into which the base member 6b is inserted, and a second groove 7d that is provided above the first groove 7c and forms a hollow space above the strain detection element 6a.

[0031] Specifically, the width of the first groove 7c in the X-axis direction is longer than the width of the base member 6b in the X-axis direction so that the base member 6b of the strain sensor 6 can be inserted. In addition, above and below the first groove 7c, protrusions 7e and 7f for holding the base member 6b protrude in the X-axis direction from the side surfaces of the left and right legs 7g and 7h on the holding portion 7b side and extend in the Z-axis direction. Therefore, the second groove 7d is shorter in the X-axis direction than the first groove 7c. In addition, the holding portion 7b has a plurality of holding grooves 7cd (three in this embodiment) formed in the Y-axis direction, so that an appropriate holding groove 7cd can be selected depending on the type of tire T and the model of the vehicle.

[0032] Furthermore, the holding portion 7b of the holding member 7 is formed with the first groove 7c and the protrusions 7e and 7f so that the distance between the bottom surface 7a and the strain sensor 6 (specifically, the base member 6b) is approximately constant. That is, the first groove 7c and the second groove 7d (holding groove 7cd) are formed with a predetermined width in the Y-axis direction along the bottom surface 7a.

[0033] The holding member 7 also has legs 7g, 7g on the bottom surface 7a side at both ends in the width direction (X-axis direction) that can come into contact with the inner surface T1 of the tire T. The shape of the legs 7g, 7h is preferably a shape (e.g., a rectangular parallelepiped) that extends substantially vertically from the bottom surface 7a upward (in other words, toward the center of the tire T when attached to the tire T).

[0034] Furthermore, as shown in FIG. 5, when a Cartesian coordinate system is defined by an X-axis (first axis) extending in the width direction of holding member 7, a Z-axis (third axis) perpendicular to the X-axis and extending in the depth direction of holding member 7, and a Y-axis (second axis) extending in a direction perpendicular to the X-axis and Z-axis, it is preferable that the shapes of legs 7g, 7h be symmetrical with respect to a plane S1 obtained by translating a plane defined by the Y-axis and Z-axis (YZ plane) to a position passing through midpoint M1 in the X-axis direction of holding portion 7b.

[0035] Furthermore, as shown in FIG. 6, when a Cartesian coordinate system is defined by an X-axis (first axis) extending in the width direction of holding member 7, a Z-axis (third axis) perpendicular to the X-axis and extending in the depth direction of holding member 7, and a Y-axis (second axis) extending in a direction perpendicular to the X-axis and Z-axis, it is preferable that the shapes of legs 7g, 7h be symmetrical with respect to a plane S2 obtained by translating a plane defined by the X-axis and Y-axis (XY plane) to a position passing through midpoint M2 in the Z-axis direction of holding portion 7b.

[0036] The holding member 7 holding the base member 6b therein has an upper portion fixed to the lower portion of the storage case 2 with an adhesive, and a bottom surface 7a attached to the inner surface T1 of the tire T, as shown in FIG.

[0037] 7 is a cross-sectional view of a retaining member 7 according to this embodiment of the present invention, to which a strain sensor 6 is attached and fixed with an adhesive 8 to the inner surface T1 of a tire T. In this embodiment, the strain sensor 6 is attached to the central retaining groove portion 7cd among three retaining groove portions 7cd arranged in the Y-axis direction.

[0038] The holding member 7 attached to the inner surface T1 of the tire T has a hollow space 7i located on the center direction side of the tire T with respect to the strain detection element 6a. The hollow space 7i in this embodiment is formed by the second groove portion 7d above the first groove portion 7c into which the base member 6b is inserted, and one holding groove portion 7cd provided above them. When the strain sensor 6 is attached to the uppermost holding groove portion 7cd of the three holding groove portions 7cd arranged in the Y-axis direction, the hollow space 7i is formed only by the second groove portion 7d above the first groove portion 7c into which the base member 6b is inserted. When the strain sensor 6 is attached to the lowermost holding groove portion 7cd of the three holding groove portions 7cd arranged in the Y-axis direction, the hollow space 7i is formed by the second groove portion 7d above the first groove portion 7c into which the base member 6b is inserted, and two holding groove portions 7cd provided above them. Therefore, the size of the hollow space 7i varies depending on the position of the first groove portion 7c into which the base member 6b is inserted.

[0039] In addition, in a state where the bottom surface 7a is attached to the inner surface T1 of the tire T, a space 7j that can be filled with adhesive is preferably formed between the base member 6b and the inner surface T1 of the tire T. Therefore, it is preferable to attach the strain sensor 6 to the holding groove portion 7cd above the lower end holding groove portion 7cd. Note that it is preferable to use an adhesive 8 filled in the space 7j that has an elastic modulus that is approximately equal to or greater than that of the tire T.

[0040] The base member 6b and the holding member 7 are fixed to the inner surface T1 of the tire T by filling the space 7j with an adhesive 8. The adhesive 8 is preferably a rubber-based elastic adhesive that has adhesion to the tire and is suitable for the hardness of the tire, such as a silicone-based or urethane-based adhesive.

[0041] In addition, the expressions "approximately equal," "approximately constant," "approximately vertical," and "approximately center" do not limit the meaning to "strictly equal," "constant," and "vertical," but allow for the range of error due to manufacturing tolerances, design tolerances, or the accumulation of these, and can be rephrased as "substantially equal," "constant," "vertical," and "center."

[0042] [effect] FIG. 8 is a schematic cross-sectional view comparing the effects of the holding member 7 according to this embodiment and a holding member 107 according to a comparative example.

[0043] The holding member 107 according to the comparative example has a space located on the tire T center side with respect to the strain detection element 6a filled with an object such as an adhesive, and does not have the hollow space 7i of the present embodiment. In this case, when a force is applied from the road surface, a force (a force directed from top to bottom in the figure) acts on the strain detection element 6a from the tire center side, which is a factor in reducing the sensitivity of the strain detection element 6a, and deformation of the base member 6b is hindered, which may reduce the sensitivity of the strain detection element 6a.

[0044] On the other hand, the holding member 7 of this embodiment has a hollow space 7i located on the center side of the tire T with respect to the strain detection element 6a. In this case, the force acting on the strain detection element 6a from the tire center side (a factor that reduces sensitivity) is eliminated, so that the base member 6b can deform more easily than in the case where there is no hollow space 7i, and the force applied from the road surface can be detected with good sensitivity by the strain detection element 6a.

[0045] Moreover, the holding member 7 preferably includes a holding portion 7b that holds the base member 6b so that the distance between the bottom surface 7a (tire inner surface T1) and the base member 6b is approximately constant. When the holding member 7 including the holding portion 7b is attached to the tire inner surface T1 by filling the space 7j below the base member 6b with adhesive, the occurrence of variation in the distance between the base member 6b (strain detection element 6a) and the tire inner surface T1 can be suppressed. This makes the degree of cushioning transmitted from the deformation strain of the tire T to the strain detection element 6a via the adhesive constant, allowing the strain to be detected with high accuracy.

[0046] Moreover, the holding member 7 is preferably formed of a cushion rubber having an elastic modulus equal to or less than that of the tire T, and the elastic modulus of the adhesive 8 filled in the space 7j between the base member 6b and the inner surface T1 of the tire T is preferably equal to or greater than that of the tire T. By adjusting the elastic modulus of the holding member 7 and the adhesive 8 in this manner, the force applied to the holding member 7 from the tire T (road surface) is absorbed by the holding member 7 and is prevented from being transmitted to the storage case 2, while the adhesive 8 easily deforms in response to the force applied from the tire T (road surface) and can easily transmit the deformation to the base member 6b (strain detection element 6a). In other words, it is possible to reduce the decrease in sensitivity of the strain detection element 6a caused by the restraint of the base member 6b by the holding member 7, and the deformation of the adhesive 8 can be accurately detected by the strain detection element 6a, so that the strain applied to the tire T can be accurately detected.

[0047] Moreover, the holding member 7 preferably has legs 7g, 7h located at both ends in the width direction (X-axis direction) and extending substantially perpendicularly from the bottom surface 7a. In this case, when the holding member 7 is adhered to the inner surface T1 of the tire T, the force pressing the holding member 7 against the inner surface T1 is prevented from dispersing in the tangential direction of the inner surface T1, and the distance between the inner surface T1 of the tire T and the base member 6b can be prevented from varying. This prevents variation in the thickness of the adhesive 8 and reduces detection errors of strain caused by variation in the thickness of the adhesive 8, allowing the strain of the tire T to be detected with high accuracy.

[0048] When a Cartesian coordinate system is defined by the X-axis (first axis) extending in the width direction of holding member 7, the Z-axis (third axis) perpendicular to the X-axis and extending in the depth direction of holding member 7, and the Y-axis (second axis) extending in a direction perpendicular to the X-axis and Z-axis, it is preferable that the shapes of legs 7g, 7h be symmetrical with respect to a plane S1 obtained by translating a plane defined by the Y-axis and Z-axis (YZ plane) to a position passing through midpoint M1 in the X-axis direction of holding portion 7b.

[0049] By forming the legs 7g, 7h in such a shape, it is possible to suppress variation in the distance between the inner surface T1 of the tire T and the base member 6b in the width direction of the holding member 7. In other words, since variation in the thickness of the adhesive 8 is suppressed and detection errors of the strain are reduced, the strain of the tire T can be detected with high accuracy.

[0050] Furthermore, when a Cartesian coordinate system is defined by the X-axis (first axis) extending in the width direction of the holding member 7, the Z-axis (third axis) perpendicular to the X-axis and extending in the depth direction of the holding member 7, and the Y-axis (second axis) extending in a direction perpendicular to the X-axis and Z-axis, the shapes of the legs 7g, 7h may be symmetrical with respect to a plane S2 obtained by translating the plane defined by the X-axis and Y-axis (XY plane) to a position passing through the midpoint M2 in the Z-axis direction of the holding part 7b.

[0051] By forming the legs 7g, 7h in such a shape, it is possible to suppress variation in the distance between the inner surface T1 of the tire T and the base member 6b in the depth direction of the holding member 7. In other words, variation in the thickness of the adhesive 8 is suppressed and detection errors of the strain are reduced, so that the strain of the tire T can be detected with high accuracy.

[0052] The strain detection element 6a is a semiconductor that outputs the amount of strain according to the change in resistance, for example, a semiconductor strain sensor. This allows for measurement with lower power consumption (for example, about 1 / 1,000) and higher sensitivity (for example, about 25,000 times) than a strain gauge.

[0053] Second embodiment Fig. 9 is a front view of a holding member according to a second embodiment of the present invention, and Fig. 10 is a side view of the holding member according to the second embodiment of the present invention.

[0054] Holding member 27 according to this embodiment differs from holding member 7 according to the first embodiment in that bottom surface 27a of holding member 27 has slit 27k that communicates between the inside and outside of space 7j (see FIG. 7).

[0055] The slit 27k is, for example, a recess provided in the center of the legs 27g, 27h in the Z-axis direction, opens downward of the legs 27g, 27h, extends in the X-axis direction of the legs 27g, 27h, and has the same width in the Y-axis direction as the second groove portion 7d.

[0056] [effect] The bottom surface 27a of the holding member 27 is provided with a slit 27k that communicates the inside and outside of the space 7j (for example, a side surface of the holding member 27). Therefore, when the space 7j of the holding member 27 is filled with adhesive 8 and the holding member 27 is pressed against the inner surface T1 of the tire T in order to attach the physical quantity detection device 21 to the inner surface T1 of the tire T, the excess adhesive 8 can be released from the space 7j to the slit 27k. This allows the holding member 27 to be bonded to the tire without applying more force than necessary to the base member 6b, and also prevents the distance between the base member 6b and the tire inner surface T1 from varying, allowing the strain to be detected with high accuracy. In addition, the adhesion area of ​​the holding member 27 to the inner surface T1 of the tire T can be increased.

[0057] In this embodiment, the slits 27k are provided in the bottom surface 27a of the holding member 27 as an escape portion for excess adhesive 8, but instead of the slits 27k, through holes that communicate the inside and outside of the space 7j can be provided in the side surface of the holding member 27. However, in this case, there is a risk that an adhesive having a lower elastic modulus than the holding member 27 will be filled in the through holes in the side surface of the holding member 27, suppressing the elastic modulus of the holding member 27. Also, the adhesion area of ​​the holding member 27 to the inner surface T1 of the tire T cannot be increased.

[0058] Third embodiment Fig. 11 is a front view of a holding member according to a third embodiment of the present invention, and Fig. 12 is a side view of the holding member according to the third embodiment of the present invention.

[0059] The retaining member 37 of this embodiment differs from the retaining member 27 of the second embodiment in that the bottom surface 37a of the retaining member 37 has one or more slits (in this embodiment, three on each of the bottom surfaces 37a of the legs 37g, 37h) that connect the inside and outside of the space 7j (see FIG. 7) formed by one or more recesses 37k.

[0060] Furthermore, the width in the Z-axis direction of each recess 37k in this embodiment is narrower than the width in the Z-axis direction of the slit 27k in the second embodiment, and a protrusion 37l is formed between two adjacent recesses 37k.

[0061] [effect] The slits that connect the bottom surface 37a of the holding member 37 to the inside and outside of the space 7j (see FIG. 2) are formed by one or more recesses 37k (three on each of the bottom surfaces 37a of the legs 37g and 37h in this embodiment). Therefore, when a force (e.g., stress) acts on the holding member 37 along the direction in which the recesses 37k are arranged, the force can be distributed and supported by the recesses 37k. As a result, compared to a case in which the recesses 37k are not provided, the load acting on the strain sensor 6 due to repeated deformation of the tire T or impact when the tire T runs over a protrusion can be distributed, and the durability of the strain sensor 6 can be improved. In addition, the adhesion area of ​​the holding member 37 to the inner surface T1 of the tire T can be further increased.

[0062] (Fourth embodiment) Fig. 13 is a front view of a holding member according to a fourth embodiment of the present invention, and Fig. 14 is a side view of the holding member according to the fourth embodiment of the present invention.

[0063] Holding member 47 according to this embodiment differs from holding member 37 according to the third embodiment in that a curved surface is formed at the corner located at the bottom of one or more recesses 47k that form the slit.

[0064] [effect] A curved surface is formed at the corners located at the bottom of one or more recesses 47k constituting the slit. Therefore, the force acting on the holding member 37 from the inner surface T1 of the tire T via the adhesive 8 can be further distributed and supported. This makes it possible to distribute the load on the strain sensor 6 caused by repeated deformation of the tire T or impact when the tire T runs over a protrusion, and further improve durability.

[0065] Fifth embodiment 15 is a cross-sectional view of a physical quantity detection device according to a fifth embodiment of the present invention. A physical quantity detection device 51 according to this embodiment differs from the physical quantity detection device 1 according to the first embodiment in that through holes 57m, 52a, and 52c that communicate a hollow space 57i of the holding member 57 with the inside of the tire T are provided in the housing case 52 that is joined to the holding member 57 and in a portion 57n of the holding member 57 that is joined to the housing case 52.

[0066] Specifically, a through hole 57m is provided in a portion 57n of the holding member 57 above the hollow space 57i that is joined to the storage case 52. A through hole 52a that communicates the through hole 57m of the holding member 57 with the inside of the storage case 52 is provided in a lower portion of the storage case 52 to which the holding member 57 is joined. Furthermore, a through hole 52c that communicates the inside of the storage case 52 with the inside of the tire T is provided in a side surface 52b of the storage case 52. Therefore, the hollow space 57i and the inside of the tire T are communicated by the through holes 57m, 52a, and 52c.

[0067] The holding member 57 of this embodiment is larger than the holding members 7 to 47 of the first to fourth embodiments, and the holding portion 57b is closed and does not penetrate in the front-rear direction (Z direction). Also, the first groove portion 57c of the lowermost holding groove portion 57cd of the holding portion 57b of the holding member 57 has a larger area of ​​the XZ surface of the first groove portion 57c of the upper holding groove portion 57cd.

[0068] [effect] The holding member 57 and the housing case 52 have through holes 57m, 52a, and 52c that communicate the hollow space 57i with the inside of the tire T. This makes it possible to suppress the occurrence of a pressure difference between the hollow space 57i and the inside of the tire, and to suppress the occurrence of a detection error due to a force acting on the strain sensor 6 due to the pressure difference.

[0069] Specifically, if the strain sensor 6 is disposed in an enclosed space, a pressure difference occurs between the inside of the tire T and the hollow space 57i due to a change in the air pressure of the tire T caused by a temperature change or the like, and a force is applied to the strain sensor 6, which may reduce the detection accuracy. In this embodiment, the housing case 52 joined to the holding member 57 and the portion 57n of the holding member 57 joined to the housing case 52 are provided with through holes 57m, 52a, 52c that communicate the hollow space 57i of the holding member 57 with the inside of the tire T. This can eliminate the pressure difference between the inside of the tire T and the hollow space 57i, and the force applied to the strain sensor 6 due to the pressure difference is eliminated, allowing the strain to be detected with high accuracy.

[0070] The present invention is not limited to the above-described embodiment, and includes various modified examples. For example, the above-described embodiment has been described in detail to clearly explain the present invention, and is not necessarily limited to those including all of the configurations described. In addition, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. In addition, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. [Explanation of symbols]

[0071] Reference Signs List 1, 21, 51...physical quantity detection device, 2...container case, 6...strain sensor, 6a...strain detection element, 6b...base member, 7, 27, 37, 47, 57...holding member, 7a, 27a, 37a...bottom surface, 7b, 57b...holding portion, 7c...first groove portion, 7d...second groove portion, 7e, 7f...ribs, 7g, 7h, 27g, 27h, 37g, 37h...legs, 7i, 57i...hollow space, 7j...space, 8...adhesive, 27k...slit, 37k, 47k...recess, 52...container case, 52a, 52c, 57m...through hole

Claims

1. A strain sensing element; a base member to which the strain detection element is fixed; a holding member that holds the base member therein and has a bottom surface that can be attached to an inner surface of a tire, The holding member has a hollow space located on a tire center direction side with respect to the strain detection element. A physical quantity detection device comprising:

2. The physical quantity detection device according to claim 1 , The holding member includes a holding groove portion that holds the base member so that the distance between the bottom surface and the base member is approximately constant. A physical quantity detection device comprising:

3. The physical quantity detection device according to claim 1 , With the bottom surface attached to the inner surface of the tire, a space capable of being filled with an adhesive is formed between the base member of the holding member and an inner surface of the tire, The bottom surface is provided with a slit that communicates the space with the outside of the holding member. A physical quantity detection device comprising:

4. 2. The physical quantity detection device according to claim 1, the retaining member is formed of a cushion rubber having an elastic modulus substantially equal to or less than that of the tire, The elastic modulus of the adhesive filled in the space between the base member of the holding member and the inner surface of the tire is approximately equal to or greater than the elastic modulus of the tire. A physical quantity detection device comprising:

5. The physical quantity detection device according to claim 1 , The holding member has legs located at both ends in the width direction and extending substantially perpendicularly from the bottom surface. A physical quantity detection device comprising:

6. The physical quantity detection device according to claim 5 , When a Cartesian coordinate system is defined by a first axis extending in the width direction of the holding member, a third axis extending in the depth direction of the holding member perpendicular to the first axis, and a second axis extending in a direction perpendicular to the first axis and the third axis, The shape of the leg portion is symmetrical with respect to a plane obtained by translating a plane defined by the second axis and the third axis to a position passing through a midpoint of the holding member in the first axial direction. A physical quantity detection device comprising:

7. The physical quantity detection device according to claim 5 , When a Cartesian coordinate system is defined by a first axis extending in the width direction of the holding member, a third axis extending in the depth direction of the holding member perpendicular to the first axis, and a second axis extending in a direction perpendicular to the first axis and the third axis, The shape of the leg portion is symmetrical with respect to a plane obtained by translating a plane defined by the first axis and the second axis to a position passing through a midpoint of the holding member in the third axis direction. A physical quantity detection device comprising:

8. The physical quantity detection device according to claim 3 , The slit is formed by one or more recesses. A physical quantity detection device comprising:

9. The physical quantity detection device according to claim 8 , A corner portion located at the bottom of the one or more recesses is formed with a curved surface. A physical quantity detection device comprising:

10. The physical quantity detection device according to claim 1 , a housing case that is joined to the holding member and a portion of the holding member that is joined to the housing case are provided with through holes that communicate the hollow space with the inside of the tire.

11. The physical quantity detection device according to claim 1 , The strain detection element is a semiconductor and outputs a strain amount according to a change in resistance. A physical quantity detection device comprising:

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