Tire grounding state measurement device

Abstract

To enable a compact device structure to highly accurately measure a grounding state of a tire.SOLUTION: A tire grounding state measurement device 10 comprises: a pseudo road surface plate 12 that has a pseudo road surface 12A; a support shaft 16 that supports a tire 1 in a groundable way on the pseudo road surface 12A in an upper part of the road surface plate; a pair-of-shaft supports 18 that horizontally supports a support shaft 16 on both sides in a shaft direction of the tire 1; an expansion / contraction mechanism unit 52 and a load adjustment unit 54 that serve as load giving means for causing tensile force pulling the support shaft 16 downward to act on the pair of shaft supports 18 and applying a load to the tire 1; a pair-of-load cells 60 that is put to the pair of shaft support 18 to detect the tensile force; a load calculation unit 62 that calculates a load to be applied to the tire 1 on the basis of the detected tensile force; and a picture-taking device 32 that is disposed below the pseudo road surface plate 12, and detects an electromagnetic wave to optically take pictures.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a tire contact state measuring device. [Background technology]

[0002] There is a demand for accurate measurement of the tire's contact state on an uneven road surface that simulates an actual road surface, and various proposals have been made. For example, Patent Document 1 discloses a method in which a tire is placed on a transparent plate having an uneven surface equivalent to an actual road surface with fluorescent liquid interposed therebetween, excitation light is irradiated onto the fluorescent liquid from below the transparent plate, and the fluorescence emitted from the fluorescent liquid is photographed with a photographing device disposed below the transparent plate.

[0003] Patent Document 2 discloses a method in which a tire is placed on a flat plate, terahertz waves are irradiated onto the tire from below the plate, and the terahertz waves reflected from the tire are detected by a detection device positioned below the plate, thereby obtaining an image of the reflected waves.

[0004] Patent Document 3 discloses a tire tread contact shape measuring device that uses an image reading means to read the shadow of the tire contact portion from below a road surface body made of a translucent material. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-084428 A [Patent Document 2] JP 2018-119928 A [Patent Document 3] JP 2004-009880 A Summary of the Invention [Problem to be solved by the invention]

[0006] In order to accurately measure the tire's contact state, it is necessary to apply a load to the tire with high accuracy, and therefore it is necessary to measure the load applied to the tire with high accuracy. On the other hand, in order to optically photograph the back side of the pseudo road plate as described above, it is necessary to place a photographing device below the pseudo road plate, and the space for measuring the load is limited. Therefore, it is not easy to accurately measure the tire's contact state with the ground with a compact device configuration.

[0007] In view of the above, an object of an embodiment of the present invention is to provide a tire contact state measuring device that can accurately measure the contact state of a tire with a compact device configuration. [Means for solving the problem]

[0008] The present invention includes the embodiments set forth below. [1] A tire contact condition measuring device comprising: a pseudo road plate having a pseudo road surface with unevenness equivalent to that of a real road surface; a support axle that supports a tire so that it can contact the pseudo road surface above the pseudo road plate; a pair of axle supports that support the support axle horizontally on both axial sides of the tire; a load application means that applies a tensile force to the pair of axle supports to pull the support axle downward, thereby applying a load to the tire; a pair of force detection devices that are incorporated in the pair of axle supports and detect the tensile force acting on the pair of axle supports; a load calculation unit that calculates the load applied to the tire based on the tensile force detected by the pair of force detection devices; and an imaging device that is arranged below the pseudo road plate and detects electromagnetic waves that have passed through the pseudo road plate and takes optical images. [2] The tire contact state measuring device described in [1], further comprising an irradiation device arranged below the pseudo road plate and irradiating electromagnetic waves to the contact portion between the tire and the pseudo road surface through the pseudo road plate. [3] The tire contact condition measuring device described in [1], further comprising an irradiation device arranged below the pseudo road plate and irradiating excitation light onto fluorescent liquid interposed between the tire and the pseudo road plate through the pseudo road plate, and the imaging device detects the fluorescence emitted from the fluorescent liquid and transmitted through the pseudo road plate. [4] The tire ground contact state measuring device according to any one of [1] to [3], further comprising wheels for supporting the tire ground contact state measuring device so that the tire ground contact state measuring device can be moved. Effect of the Invention

[0009] According to the present embodiment, it is possible to provide a tire contact state measuring device that can accurately measure the contact state of a tire with a compact device configuration. [Brief description of the drawings]

[0010] [Figure 1] 1 is a front view of a tire ground contact state measuring device according to an embodiment; [Diagram 2] FIG. 2 is a plan view of an installation stand constituting the tire ground contact state measuring device. [Diagram 3] FIG. 2 is a diagram showing a schematic configuration of the tire contact state measuring device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A tire ground contact state measuring device according to an embodiment will be described below with reference to the drawings.

[0012] 1 is a diagram showing a tire ground contact state measuring device 10 (hereinafter, sometimes simply referred to as "the measuring device 10") according to one embodiment. The measuring device 10 is a device that measures the ground contact state of a tire 1 that is grounded on a pseudo road surface 12A of a pseudo road surface plate 12 by detecting electromagnetic waves that have passed through the pseudo road surface plate 12.

[0013] Electromagnetic waves are a phenomenon in which periodic changes in electric and magnetic fields propagate through space as waves. There are no particular limitations on electromagnetic waves, and examples of such waves include X-rays, ultraviolet rays, visible light, infrared rays, and radio waves (including terahertz waves).

[0014] As an embodiment, a measuring device 10 that irradiates excitation light onto a fluorescent liquid interposed between a tire 1 and a simulated road surface 12A and detects the fluorescence emitted from the fluorescent liquid to measure the tire's contact state on a wet road surface will be described below. Each substance that has fluorescent properties has its own specific absorption wavelength range and fluorescence wavelength range. The fluorescence used for imaging is generally in the visible light range, but it may be electromagnetic waves invisible to the human eye, such as ultraviolet light or infrared light. Generally, ultraviolet light or visible light is used as the excitation light, but it is selected according to the absorption wavelength range of the substance of interest.

[0015] 1, the measuring device 10 includes a pseudo road surface plate 12, a table 14 on which the pseudo road surface plate 12 is placed, a support shaft 16 that supports a tire 1, a pair of shaft supports 18, 18 that support the support shaft 16, and a base stand 20. The table 14 and the pair of shaft supports 18, 18 are provided on the base stand 20.

[0016] As shown in Fig. 3, the pseudo road surface plate 12 has a pseudo road surface 12A having projections and recesses equivalent to an actual road surface on one of its front and back surfaces, and in this example, the surface opposite the pseudo road surface 12A is flat. The pseudo road surface plate 12 is rectangular in plan view as shown in Fig. 2, and may be formed into the square shape shown in Fig. 2 by a single plate, or may be formed into the square shape by combining a plurality of band-shaped plates.

[0017] The pseudo road surface plate 12 is a flat plate through which electromagnetic waves can pass, and is preferably a transparent plate. The method for producing the transparent pseudo road surface plate 12 having the pseudo road surface 12A is not particularly limited, and it can be produced, for example, by molding asphalt corresponding to the actual road surface with silicone rubber, pouring a transparent resin into the mold, and curing it in a vacuum degassed state. The transparent resin can be, for example, a urethane-based resin.

[0018] The simulated road surface plate 12 is replaceably placed on a table 14, and a number of plates with various uneven shapes are prepared according to the road surface to be tested, and one of them can be selected and installed.

[0019] The table 14 includes a mounting stand 22 for horizontally mounting the pseudo road surface plate 12. The mounting stand 22 is provided on the top plate of the table 14. The pseudo road surface plate 12 is mounted on the upper surface of the mounting stand 22 with the pseudo road surface 12A facing upward.

[0020] 2, the installation stand 22 is provided with an observation window 24, which is a rectangular opening, so that the contact area 5 between the tire 1 and the simulated road surface 12A can be observed from below through the simulated road surface plate 12. The simulated road surface plate 12 is installed on the installation stand 22 so as to cover the observation window 24 from above. Reference numeral 26 denotes a fixing block for positioning and fixing the simulated road surface plate 12 on the installation stand 22. The contact area 5 is an area where the tire 1 is deemed to be in contact with the simulated road surface 12 from the outside, and is also referred to as the tire contact surface.

[0021] Below the installation stand 22, which is the top board of the table 14, there are provided an irradiation device space 30 for installing the irradiation device 28 and an imaging device space 34 for installing the imaging device 32, which are divided into upper and lower spaces by a shelf board 36.

[0022] An irradiation device 28 for irradiating electromagnetic waves to the contact portion 5 between the tire 1 and the pseudo road surface 12A through the pseudo road surface plate 12 is provided in the irradiation device space 30 above the shelf board 36.

[0023] In this example, the irradiation device 28 includes a light source 38, a filter 40, and a dichroic mirror 42, as shown in Fig. 3. The light source 38 irradiates excitation light onto the fluorescent liquid 2 interposed between the tire 1 and the simulated road surface 12A. The filter 40 transmits and separates only light of a specific wavelength from the light irradiated from the light source 38. The dichroic mirror 42 reflects only the light of the specific wavelength separated by the filter 40. The irradiation device 28 may be configured to be movable in the horizontal direction so that the irradiation position of the excitation light on the ground contact portion 5 can be changed.

[0024] The photographing device 32 is provided in the photographing device space 34 below the shelf board 36 for optically photographing by detecting electromagnetic waves transmitted through the artificial road surface plate 12. The photographing device 32 is installed on a photographing device installation stand 44 provided on the base stand 20.

[0025] The imaging device 32 detects electromagnetic waves that travel downward from the contact portion 5 between the tire 1 and the simulated road surface 12A through the simulated road surface plate 12. For example, the imaging device 32 may detect reflected waves that are formed when the electromagnetic waves irradiated from the irradiation device 28 are reflected by the contact portion 5, or may detect electromagnetic waves emitted from the contact portion 5 due to the electromagnetic waves irradiated from the irradiation device 28.

[0026] In this example, the imaging device 32 detects the fluorescence emitted from the fluorescent liquid 2 present in the ground contact portion 5 and transmitted through the pseudo road surface plate 12. The imaging device 32 is equipped with a filter 46 that transmits and separates only light of a specific wavelength from the fluorescence that has transmitted through the pseudo road surface plate 12, and a camera 48 that images the fluorescence that has transmitted through the filter 46 (see FIG. 3). For example, a single-lens reflex camera may be used as the camera 48. The imaging device 32 may be configured to be movable in the horizontal direction in accordance with the above-mentioned movement of the irradiation device 28.

[0027] The light source 38 can be appropriately selected to match the excitation spectrum of the fluorescent dye contained in the fluorescent liquid, and a light source having a peak wavelength near the peak wavelength of the excitation spectrum (e.g., a mercury lamp or an ultraviolet LED) is preferably used.

[0028] The dichroic mirror 42 and the filters 40, 46 can be appropriately selected and used according to the excitation spectrum and fluorescence spectrum of the fluorescent dye to be used. Examples of the filters 40, 46 include a wavelength-selective fluorescence filter that removes noise when detecting fluorescence, a high-pass filter (long-pass filter) that cuts off light on the shorter wavelength side than a specified wavelength and transmits light on the longer wavelength side, a low-pass filter (short-pass filter) that cuts off light on the longer wavelength side than a specified wavelength and transmits light on the shorter wavelength side, and a band-pass filter that transmits only light in a certain wavelength range and cuts off other light on the shorter and longer wavelength sides.

[0029] 1, the support shaft 16 is an axis member (shaft) that supports the tire 1 so as to be able to contact the pseudo road surface 12A above the pseudo road surface plate 12, and is provided above an installation stand 22. The tire 1 is mounted on the rim of a wheel 3, and the support shaft 16 is attached so as to pass through the center of the wheel 3. The wheel 3 is fixed to the support shaft 16 by using a wheel fixing disk 50.

[0030] The shaft supports 18, 18 are provided in a pair on the left and right so that the support shaft 16 supporting the tire 1 can be supported horizontally on both axial sides of the tire 1. The pair of shaft supports 18, 18 are columns provided upright on the base stand 20 and support the support shaft 16. A shaft chuck 51 is provided at the upper end of the shaft support 18, and the support shaft 16 is attached to the upper end of the shaft support 18 using the shaft chuck 51. The pair of shaft supports 18, 18 are provided on both sides of the table 14 and support both ends of the support shaft 16. Therefore, the table 14 is provided between the pair of left and right shaft supports 18, 18.

[0031] The measuring device 10 is provided with a load applying means for applying a tensile force to the pair of shaft supports 18, 18 to pull the support shaft 16 downward, thereby applying a load to the tire 1. In this example, the load applying means includes a pair of extension mechanisms 52, 52 that can extend or retract the length of the pair of shaft supports 18, 18, and a load adjustment unit 54 that adjusts the load by extending or retracting the pair of extension mechanisms 52, 52 in the vertical direction. By shortening the length of the pair of shaft supports 18, 18, the support shaft 16 is pulled downward, and the load applied to the tire 1 can be increased. In addition, by extending the length of the pair of shaft supports 18, 18, the support shaft 16 moves upward, and the load applied to the tire 1 can be reduced.

[0032] In detail, each shaft support 18 is configured by vertically connecting a rotatable lower column member 56 having at least an upper end with a male threaded portion 56A with a thread cut on the outer periphery, and an upper column member 58 having at a lower end with a female threaded portion 58A that screws with the male threaded portion 56A. By rotating the lower column member 56, the screwing position of the male threaded portion 56A and the female threaded portion 58A changes, and each shaft support 18 expands and contracts. Therefore, each expansion mechanism portion 52 is configured by a rotatable male threaded portion 56A and a female threaded portion 58A that screws with it. Note that instead of providing the male threaded portion 56A on the rotatable lower column member 56, a female threaded portion may be provided, and a male threaded portion that screws with this may be provided at the lower end of the upper column member 58.

[0033] The load adjustment unit 54 extends and retracts the pair of extension mechanism units 52, 52 by controlling the rotation of the lower pillar member 56, and in this example is constituted by a manual handle 54A.

[0034] The telescopic mechanisms 52, 52 of the pair of shaft supports 18, 18 are configured to telescopically extend and retract in a synchronized manner. Therefore, when the handle 54A is rotated, the lower pillar members 56 of the pair of shaft supports 18, 18 rotate in a synchronized manner, whereby the pair of shaft supports 18, 18 telescopically extend and retract in a synchronized manner, and the force applied to the shaft supports 18, 18 becomes equal on the left and right.

[0035] The load adjustment unit 54 may be configured to control the rotation of the lower pillar member 56 by motor control, rather than by the handle 54A.

[0036] The measuring device 10 is provided with a pair of load cells 60, 60 as force detection devices that detect the tensile force acting on the pair of shaft supports 18, 18. The load cells 60 are respectively incorporated into each shaft support 18, and more specifically, into the upper pillar members 58. The load cells 60 detect the force acting on the shaft supports 18 in the vertical direction.

[0037] 1, a pair of left and right support rods 61, 61 are provided on both sides of the load cell 60. To enable the load cell 60 to detect tensile force, both ends of the support rod 61 are not fixed to upper and lower members, i.e., the support rod 61 is configured to be free to move up and down.

[0038] The measuring device 10 is provided with a load calculation unit 62 that calculates the load applied to the tire 1 based on the tensile forces detected by the pair of load cells 60, 60. The load calculation unit 62 sums up the left and right tensile forces generated by shortening the length of the pair of shaft supports 18, 18, and calculates the load applied to the tire 1 due to the tensile forces, and can be configured by a computer such as a simple microprocessor.

[0039] The measuring device 10 is provided with a load display unit 64 that displays the load on the tire 1 calculated by the load calculation unit 62. The load display unit 64 can be configured with a general display, and in this example, is provided on the base 20 together with the load calculation unit 62 and the handle 54A.

[0040] The measuring device 10 includes wheels 66 that movably support the measuring device 10. The wheels 66 are attached to the lower surface of the base stand 20, and are provided at each of the four corners of the rectangular base stand 20, for example.

[0041] In one embodiment, when measuring the tire ground contact state using the measurement device 10, the simulated road surface plate 12 is fixed to the installation stand 22, and the fluorescent liquid 2 is poured onto the simulated road surface 12A. As the fluorescent liquid 2, for example, an aqueous solution containing a hydrophilic fluorescent dye (e.g., pyranine) whose peak wavelength difference between the excitation spectrum and the fluorescence spectrum is 100 nm or more is used.

[0042] Next, the tire 1 mounted on the wheel 3 is fixed to the support shaft 16, and the support shaft 16 is attached so as to span between a pair of shaft supports 18, 18, and the tire 1 is brought into contact with the simulated road surface 12A. As a result, the tire 1 is brought into contact with the simulated road surface 12A with the fluorescent liquid 2 interposed between the tire 1 and the simulated road surface 12A.

[0043] Next, by turning the handle 54A of the load adjustment unit 54, the lower pillar members 56, 56 of the pair of shaft supports 18, 18 rotate, and the upper pillar members 58, 58 move downward while synchronously on the left and right, and the pair of shaft supports 18, 18 contract. As a result, a force (tensile force) that pulls the support shaft 16 downward acts on the pair of shaft supports 18, 18, and a load is applied to the tire 1. At that time, the load cell 60 incorporated in each shaft support 18 detects the tensile force acting on the shaft support 18, and based on that, the load calculation unit 62 calculates the load applied to the tire 1, and the calculated load is displayed on the load display unit 64. Therefore, it is possible to accurately apply a specified load (for example, a load equivalent to an actual vehicle load) to the tire 1 while watching the displayed load.

[0044] After applying a predetermined load to the tire 1 in this manner, excitation light is irradiated from the light source 38 of the irradiation device 28 as shown in Fig. 3. The excitation light irradiated from the light source 38 is separated by a filter 40 into light having a predetermined wavelength (e.g., 400 nm) or less. The separated excitation light is reflected by a dichroic mirror 42 and irradiated from the lower surface of the pseudo road surface plate 12 onto the fluorescent liquid 2 interposed between the tire 1 and the pseudo road surface 12A. This causes the fluorescent dye contained in the fluorescent liquid 2 to transition from the ground state to an excited state. The excited fluorescent dye then returns to the ground state, emitting fluorescence at that time.

[0045] The emitted fluorescence passes through the pseudo road surface plate 12 and then through the dichroic mirror 42, whereupon the fluorescence of a predetermined wavelength or longer (for example, 480 nm or longer) is separated by the filter 46, and the separated fluorescence is photographed by the camera 48 of the photographing device 32. This allows the brightness distribution of the fluorescence (fluorescence intensity image) to be obtained.

[0046] The obtained luminance distribution is converted into a film thickness distribution of the fluorescent liquid 2 by a known method, and binarized with an arbitrary film thickness as a threshold based on the obtained film thickness distribution. Then, the area below the threshold is determined as the area where the tire 1 and the simulated road surface 12A are in contact with each other, and for example, the area where the tire 1 and the simulated road surface 12A are actually in contact with each other can be calculated. This makes it possible to accurately measure the actual contact area of ​​the tire with the uneven road surface that simulates the actual road surface.

[0047] The measuring device 10 according to the embodiment described above can accurately measure the ground contact state of the tire 1 with a compact device configuration. In detail, the support shaft 16 that supports the tire 1 above the pseudo road plate 12 is supported by a pair of left and right shaft supports 18, 18 on both sides of the tire 1 in the axial direction, and a load cell 60 that detects the tensile force acting on each shaft support 18 is incorporated in the shaft support 18. This makes it possible to measure the load applied to the tire by making it possible to detect the tensile force even with a compact configuration. In addition, while measuring the load with the load calculation unit 62, the expansion mechanism unit 52 and the load adjustment unit 54 as load application means can apply a load to the tire 1. Therefore, the specified load can be applied to the tire 1 with high accuracy, and the tire ground contact state can be measured with high accuracy.

[0048] As a structure for supporting the tire, it is possible to support the tire load, for example, by a cantilever beam instead of the above-described pair of left and right shaft supports 18, 18. However, in the case of a cantilever beam, the shaft support needs to be sufficiently reinforced to ensure rigidity, which increases the mass, and a three-component force meter that simultaneously measures forces in three orthogonal directions is required as a force detection device to measure the load, which increases costs.

[0049] In addition, as a configuration for measuring the load applied to the tire, instead of incorporating the load cell 60 in each shaft support 18 as described above, for example, a load cell may be incorporated in the bottom surface of the pseudo road surface plate 12 or the bottom surface of the device body to detect the compression force and thereby measure the load applied to the tire. However, when the imaging device 32 is provided below the pseudo road surface plate 12 as in the above embodiment and the irradiation device 28 is further provided, the space below the pseudo road surface plate 12 is limited. In a configuration in which a load cell is incorporated in the bottom surface of the pseudo road surface plate 12 or the bottom surface of the device body, the height of the support shaft 16 supporting the tire 1 is accordingly increased. Therefore, the workability when mounting and removing the tire 1 may be impaired. By incorporating the load cell 60 in each shaft support 18, the height of the support shaft 16 can be reduced to, for example, about 100 to 140 cm, and the workability when mounting and removing the tire 1 is excellent. Furthermore, if the height of the support shaft 16 increases, the pair of shaft supports 18, 18 will also become taller, making it necessary to reinforce the shaft supports 18, 18, which will lead to an increase in mass; however, according to the above embodiment, such an increase in mass can also be suppressed.

[0050] As described above, according to this embodiment, by adopting the tire support configuration and the load measurement configuration described above, it is possible to achieve cost reduction, compactness, weight reduction, and improvement in workability.

[0051] In the measuring device 10 according to the above embodiment, wheels 66 are provided on the base 20 to make it movable, so that it can be easily moved to rooms with different test environments, such as a low-temperature room or a high-temperature room, facilitating measurements in a variety of test environments. In this case, it is preferable that the entire measuring device 10 is sized to fit on an elevator, which further improves the convenience of the measuring device 10.

[0052] Although the embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0053] 1... tire, 2... fluorescent liquid, 5... ground contact portion, 10... tire ground contact state measuring device, 12... simulated road surface plate, 12A... simulated road surface, 16... support shaft, 18... shaft support, 28... irradiation device, 32... imaging device, 52... extension mechanism section (load application means), 54... load adjustment section (load application means), 60... load cell (force detection device), 62... load calculation section, 66... ​​wheel

Claims

1. A pseudo road surface plate having a pseudo road surface having unevenness equivalent to an actual road surface; a support shaft that supports a tire so as to be able to contact the pseudo road surface above the pseudo road plate; A pair of shaft supports that horizontally support the support shaft on both axial sides of the tire; a load applying means for applying a load to the tire by applying a tensile force to the pair of shaft supports so as to pull the support shaft downward; a pair of force detection devices incorporated in the pair of shaft supports to detect tensile forces acting on the pair of shaft supports; a load calculation unit that calculates a load applied to the tire based on the tensile forces detected by the pair of force detection devices; an imaging device disposed below the pseudo road surface plate for detecting electromagnetic waves transmitted through the pseudo road surface plate and for optically imaging the same; A tire contact state measuring device comprising:

2. 2. The tire contact state measuring device according to claim 1, further comprising an irradiation device disposed below the pseudo road plate and irradiating an electromagnetic wave through the pseudo road plate to a contact portion between the tire and the pseudo road surface.

3. 2. The tire contact state measuring device according to claim 1, further comprising an irradiation device arranged below the pseudo road plate and irradiating excitation light onto fluorescent liquid interposed between the tire and the pseudo road plate through the pseudo road plate, and the imaging device detects fluorescence emitted from the fluorescent liquid and transmitted through the pseudo road plate.

4. 4. The tire ground contact state measuring device according to claim 1, further comprising wheels for movably supporting the tire ground contact state measuring device.

Images