JP2012154858A - Method and apparatus for measuring shape of tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure the shape of a contact area of a tire running on the ground and the shape of the tire surface including the vicinity of the contact area.SOLUTION: A tire T is brought into contact with a transparent hardened glass G configuring a travel road 11a of a road surface 11. White liquid L is supplied into a road surface pool provided on the surface of the hardened glass G. A ball bearing 163a of a moving mechanism 163 is rotated to move a guide member 162 holding the road surface 11 in a front/rear direction along a guide rail 161. A CCD camera 14 disposed opposite to the side where the tire T comes in contact with the hardened glass G images a shape of the tire T running in the liquid L to measure the shape of the tire T from the captured image.

Description

  The present invention relates to a method and an apparatus for measuring a tire shape, and more particularly to measurement of a tire shape centering on a contact boundary surface with a road surface.

  Conventionally, as a method for measuring the shape of the tire in the vicinity of the ground contact surface, the tire tread surface is grounded on a pedestal, and the groove shape of the tread is detected by a laser displacement meter from the side surface of the tire or in the front-rear direction (eg, patent Reference 1) and the tire is pressed against the upper surface of the transparent tempered glass plate and irradiated with light from the lower surface side of the tempered glass plate, and acts on the tempered glass plate from the amount of reflected light totally reflected on the upper surface of the tempered glass plate. A method of estimating the tire contact surface shape by obtaining a tire pressure distribution (see, for example, Patent Document 2), or applying a predetermined load to a measurement pad simulating a tread pattern of a tire and pressing it against a glass plate, Opacity of the grounded part of the tread by passing this measuring pad through a liquid with a certain level of opacity placed on a glass plate at various speeds Observed through the glass plate, a method of estimating the ground contact surface shape of the tire from the floatation volume of the tread (e.g., see Patent Document 3) and the like are known.

JP 2008-122098 A Japanese Utility Model Publication No. 7-2944 JP 10-239136 A

However, in the method using the laser displacement meter, the side portion of the tire can be measured without any problem, but the laser beam does not reflect because the measurement target surface and the incident direction of the laser beam are substantially parallel at the ground boundary surface. Therefore, in Patent Document 1, the laser beam incident side of the pedestal is configured with a transparent plate, and a reflecting plate is provided in the pedestal to bend the laser beam and irradiate the tire ground contact surface to change the tread surface deformation state. I try to detect it. Therefore, a part of the pedestal is made of a transparent material, and it is necessary to form a storage hole for storing the reflection plate in the pedestal and install the reflection plate.
In addition, measurement with a laser displacement meter has only one measurement point per displacement meter, and even if a line laser is used, only one line can be measured at a time. Shape measurement could not be performed at the same time. That is, the measurement by the laser displacement meter is not suitable for the measurement of the contact surface shape in a state where the tire is running.
Also, in the method of estimating the tire contact surface shape from the pressure distribution of the tire acting on the tempered glass plate, the light source is a point light source and the total reflected light is detected by a photomultiplier tube. Similar to the measurement by, it was difficult to measure the shape of the contact surface when the tire was running.

In addition, in the method of estimating the tread floating amount from the opacity of the tread contact portion, the speed of the measuring pad, that is, the floating amount of the measuring pad due to the flow rate of the liquid is measured. Since the measurement pad is configured to be pressed against the glass plate under a predetermined load, the measurement pad can move but cannot rotate. Therefore, even in this conventional example, it is difficult to measure the contact surface shape when the tire is running.
As a method for measuring the contact surface shape while the tire is running, a method of pressing the tire on pressure-sensitive paper or the like is conventionally known, but in this method, the slip angle or braking / driving force is applied to the tire. It was difficult to measure the correct ground contact surface shape due to wrinkles on the paper. Furthermore, this method has a problem in that although the contact surface shape can be obtained, the tire shape in the vicinity of the contact surface cannot be measured.
In addition, as for the shape of the running tire, attempts have been made to predict the contact shape including the contact surface shape and the deformation of the tire by model calculation using FEM or the like. Therefore, it is difficult to prove the correctness of the calculation in the present situation where the actual measurement is difficult.

  The present invention has been made in view of the conventional problems, and provides a method and an apparatus for accurately measuring the contact surface shape and the tire surface shape including the vicinity of the contact surface when the tire is running. With the goal.

The invention according to claim 1 of the present application is an apparatus for measuring the shape of a tire when it is in contact with the road surface, the tire holding means for holding the tire rotatably, and at least the portion where the tire contacts the ground. An imaging means having a transmission part made of a material that transmits light and extending in the front-rear direction of the tire, and an imaging unit that is installed on the opposite side of the transmission part from the side where the tire contacts the ground A light projecting unit that is installed on the same side as the imaging unit and irradiates the tire with light, and an image processing unit that calculates the luminance data of each pixel by image processing the tire image captured by the imaging unit , A shape measuring means for measuring the shape of the tire from the calculated luminance data, and a moving hand for moving the road surface relative to the tire and the imaging means in the front-rear direction of the tire. Characterized by comprising and.
Thereby, since the state where the tire travels on the road surface can be realized, the state of the tire contact surface and the deformation state of the tire near the contact surface can be accurately measured. Also, by giving the tire a slip angle or camber angle, it is possible to measure the deformation state of the tire when lateral force is input to the tire, so the tire shape in the actual running state can be accurately reproduced Can do.
The moving means may be a means for moving the road surface, or a means for simultaneously moving the tire and the imaging means. The light projecting means may be fixed together with the tire and the imaging means, or may be installed so as to move together with the tire and the imaging means, or may be fixed together with the road surface or installed so as to move together with the road surface. May be.

Invention of Claim 2 is a tire shape measuring device of Claim 1, Comprising: It accommodates in the space formed by the frame provided in the tire side of the said road surface, and the said road surface and the said frame And a liquid that forms a liquid layer on the upper surface of the transmission part.
As a result, the amount of liquid entering the tire tread surface and the shape of the tire portion immersed in the liquid can be measured with high accuracy, so that it is possible to accurately grasp the running state of the tire on a wet road such as a slip state. it can.
According to a third aspect of the present invention, in the tire shape measuring apparatus according to the second aspect, a white liquid or a white colored liquid is used as the liquid.
In this way, the liquid is white, which is the opposite color to black, which is the color of the tire, and the depth of penetration of the liquid in the tire tread or the depth of the tire actually immersed in the white shade of the photographed image. Since the height can be accurately measured, the measurement accuracy of the tire shape can be further improved.

Invention of Claim 4 is a tire shape measuring apparatus in any one of Claims 1-3, Comprising: The mechanism which provides either one or both of braking force and driving force to the said tire is provided. It is characterized by that.
Thereby, it is possible to accurately measure the state of the tire contact surface and the deformation state of the tire near the contact surface due to the difference in slip ratio during braking and driving.

According to a fifth aspect of the present invention, a tire is grounded on a transparent plate, and the tire is irradiated with light from a side opposite to a side where the tire touches the transparent plate to photograph the shape of the tire. In the tire shape measuring method for measuring the shape of the tire from a photographed image, a liquid layer comprising a white liquid or a white colored liquid on the surface of the transparent plate while rotatably holding the tire The shape of the tire is photographed while moving the transparent plate in the front-rear direction of the tire.
This allows the tire to run while rotating on a road surface provided with a liquid layer, so it can accurately measure the amount of liquid entering the tire tread and the shape of the tire centered on the ground contact interface with the ground. can do. Therefore, it is possible to provide data that serves as an index for considering the tire performance.

  The summary of the invention does not list all necessary features of the present invention, and a sub-combination of these feature groups can also be an invention.

It is a side view which shows the structure of the tire shape measuring apparatus which concerns on this Embodiment. It is a front view which shows the structure of the tire shape measuring apparatus which concerns on this Embodiment. It is a figure which shows the acquisition method of the data for calibration (depth and light and shade). It is a figure for demonstrating the relationship between the contrast of an image, and the liquid depth. It is a figure which shows the method of correct | amending the dispersion | variation in light quantity. It is a figure which shows an example of a picked-up image. It is a figure which shows an example of the measurement result of a tire shape. It is a figure which shows the tire shape measuring method by this invention. It is a figure which shows the other example of the tire shape measuring apparatus by this invention.

  Hereinafter, the present invention will be described in detail through embodiments, but the following embodiments do not limit the invention according to the claims, and all combinations of features described in the embodiments are included. It is not necessarily essential for the solution of the invention.

1 and 2 are diagrams showing a configuration of a tire shape measuring apparatus 10 according to the present embodiment. In each figure, 11 is a road surface, 12 is a tire holding means, 13 is a braking / driving means, and 14 is an imaging means. A CCD camera, 15 is an LED line light source as a light projecting means, 16 is a moving means, 17 is an image processing means, and 18 is a shape measuring means.
In this example, the CCD camera 14 and the moving means 16 are mounted on a base 21 that is a fixed member, and the tire holding means 12 is attached to an attachment frame 22 erected on the base 21. The road surface 11 and the LED line light source 15 are attached to the moving means 16 via the road surface holding member 23.
The road surface 11 includes a traveling portion 11a made of a transparent material that transmits light, and a running portion 11b as a road surface for running-in running-in. The tire T is grounded by the tire holding means 12 so that the front-rear direction (traveling direction) is the longitudinal direction of the traveling unit 11a. Hereinafter, the left-right direction in FIG. 1 is referred to as the front-rear direction, the direction perpendicular to the paper surface is referred to as the width direction, and the up-down direction in FIG.
In this example, as will be described later, the road surface 11 moves, but assuming that the road 11 is stationary, the traveling direction of the tire is the front side, and the running portion 11b is the rear side. Located on the side. Further, the position of the upper surface of the running portion 11b is higher than the upper surface of the traveling portion 11a.

The travel part 11a is composed of a transparent tempered glass plate G that is long in the front-rear direction, and is held by road surface holding members 23 on both sides in the width direction of the tempered glass plate G.
The road surface holding member 23 includes, for example, a frame 23a erected on a guide member 162, which will be described later, and a support piece 23b attached to the frame 23a and supporting the end portion in the width direction of the tempered glass sheet G from below. . The frame 23a regulates the end of the tempered glass sheet G in the width direction at the top.
The length obtained by removing the thickness of the frame body 19 for constituting the road surface pool described later from the length in the longitudinal direction of the tempered glass sheet G is the road surface length on which the tire T travels, and the frame body is determined from the length in the width direction. The length excluding the thickness of 19 is the road surface width.
As the road surface length, when the tire shape is measured in a so-called free rolling state in which the longitudinal force, slip angle, camber angle, etc. are not applied to the tire T, it is sufficient that the rolling circumference of the tire T is 1/4 or more. It is. However, when the tire shape is measured in a state where the front and rear force is generated by braking / driving the tire T or a lateral force is generated by applying a slip angle / camber angle, in order to stabilize the ground contact behavior of the tire, A road surface length of about 1/3 to 1 round of the rolling circumference of T is required.
As for the road surface width, it is sufficient if it is 1.5 times or more the tire width of the tire T to be tested. If the road surface width is too narrow, the light source may appear in the camera. In addition, when the road surface width is too wide, it is necessary to increase the amount of light from the light source. However, if this is done, unevenness in the light intensity distribution of the light source over the entire road surface is likely to occur, so it should be 2 to 5 times the tire width. It is preferable that the maximum is 10 times or less.
In addition, as a road surface material which is a material constituting the traveling unit 11a, in addition to the tempered glass plate G used in this example, a material having a high light transmittance such as acrylic or transparent plastic may be used. In any case, it is necessary to have a strength capable of withstanding the load acting on the tire T. If the strength is weak, the road surface 11 is deformed or damaged due to the application of tire load, lateral force, or longitudinal force, and the accuracy of the measurement data decreases.
Moreover, it is preferable that the surface of the road surface 11, especially the surface of the traveling part 11a is a smooth surface without unevenness. The specific smoothness is appropriately determined depending on the required accuracy of the shape to be measured. For example, if the required accuracy is 0.2 mm, the maximum unevenness of the road surface 11 needs to be at least half that is 0.1 mm or less.

The road surface 11 of the tire shape measuring apparatus 10 of the present example holds a liquid L that is colored on the surface of the traveling unit 11a.
The liquid L is stored in a road surface pool surrounded by a tempered glass plate G that constitutes the traveling unit 11a and a frame body 19 provided on the upper surface of the tempered glass plate G. This liquid L constitutes a liquid layer on the tempered glass plate G. In this example, as the frame body 19, the front wall 19 a and the rear wall 19 b erected at the front and rear ends of the upper surface of the tempered glass sheet G, and the left erected at both ends in the width direction of the tempered glass sheet G. The cross section composed of the wall 19c and the right wall 19d is rectangular. Instead of the frame body 19, the road surface pool may be formed by processing the tempered glass sheet G constituting the traveling portion 11 a into a form that surrounds the end portion with a frame having a height. When the material is acrylic or transparent plastic, the road surface pool may be formed at the time of molding.
The upper surface of the rear wall 19b is at the same height as the upper surface of the run-up portion 11b, and a slope (slope) 19k is provided in front of the rear wall 19b. This slope 19k is provided for the tire T to move smoothly from the running portion 11b to the running portion 11a, and as shown in FIG. 1, the height on the rear wall 19b side, which is the rear, is the height of the rear wall 19b. It is composed of a member having a right-angled triangular cross section whose height is equal to the height and decreases in the forward direction.
Further, the depth of the liquid L stored in the road surface pool may be a minimum of 0.1 mm and a depth that allows the entire tire T to be immersed at the maximum. Practically, if the depth of the liquid L is in the range of 0.5 mm to 10 mm, the behavior of the tire on the actual WET road surface can be grasped.
The viscosity of the liquid L is preferably about the same as that of water and less than that. This is because if the viscosity of the liquid is too high, the grounding characteristics are affected. Moreover, in order to reproduce the driving | running | working at the time of rain, it is especially preferable to set it as the same viscosity as water.
Moreover, as the liquid L, since the surface of the tire T is black, it is preferable to use water colored with a white pigment or dye, or a white liquid.

Furthermore, it is preferable to use a liquid L that is not completely opaque, and has a transparency that can be taken for tire shapes other than the contact surface by adjusting the concentration or the amount of the colorant, and is linear with respect to the depth. It is particularly preferable to use a material that transmits light. As a result, the shade from white to black of the photographed image becomes the tire shape as it is. However, even if it is not linear, if the data for calibration is acquired by examining the relationship between depth and shade in advance, the tire shape can be obtained from the shade using this calibration data. Even when it is expected to be linear, it is preferable to confirm in advance the relationship between depth and shading.
As a method for acquiring calibration data, for example, as shown in FIG. 3, a frame body 32 is provided around a glass plate 31 made of the same material as the tempered glass constituting the traveling portion 11a, and the glass plate 31 and the frame body are provided. The steel plate 33 having a thickness half the depth of the liquid L (here, 0.5 mm) and colored in the same black color as the tire T to be measured; A square pillar 34 having a thickness of 1 mm or more is prepared, the iron plate 33 is brought into close contact with the glass plate 31, one end 34 a of the square member 34 is placed on the iron plate 33, and the other end 34 b is placed on the glass plate 31. Then, the iron plate 33 and the square member 34 are photographed from the lower side of the glass plate 31 using the CCD camera 14. The thickness of the liquid L between the glass plate 31 and the square member 34 is 0.5 mm on the iron plate 33 side, decreases as it goes to the other end 34b side of the square member 34, and becomes 0 mm on the other end 34b. Therefore, as shown in FIG. 4, the end portion 33 a opposite to the side on which the square member 34 side of the iron plate 33 is placed is the origin O, and the distance x measured from the origin O toward the other end 34 b of the square member 34. Relationship between light and shade of photographed image (photographed image) (solid line is a measurement example, one-dot chain line is an example using a liquid that transmits light linearly with respect to the depth), and the depth of the liquid L (liquid depth) ) And the distance x, calibration data indicating the relationship between the depth of the liquid and the density of the photographed image can be obtained.

The tire holding means 12 includes a tire support member 121 that rotatably supports the tire shaft J of the tire T via a bearing (not shown), and a force that presses the tire T against the road surface 11 by moving the tire support member 121 up and down. A cylinder device 122 for adjusting (load) and a force meter 123 are provided.
The cylinder device 122 includes a cylinder body 122b whose one end is connected to the tire support member 121 and a cylinder body 122b that drives a piston (not shown) provided on the other end side of the cylinder rod 122a to expand and contract the length of the cylinder rod 122a. Is provided. The cylinder body 122b is attached to the attachment frame 22. In this example, a hydraulic cylinder is used as the cylinder device 122.
The component force meter 123 has a function of measuring and recording a tire axial force, which is a force in the front-rear direction that is attached to the tire shaft J and acts on the tire shaft J.
In this example, the horizontal frame of the mounting frame 22 includes a vertical frame 22a erected on the base 21 and a horizontal frame 22b that protrudes in the horizontal direction and parallel to the tire width direction from the upper end of the vertical frame 22a. The cylinder body 122b is fixed to 22b.
Thus, since the tire T is rotatably held by the tire holding means 12 including the cylinder device 122, the tire T is grounded with a predetermined load on the road surface 11 and when the road surface 11 moves in the front-rear direction, the tire T It rotates due to friction with the road surface 11. Thus, when the road surface 11 moves backward (rightward in FIG. 1), the tire T travels forward (leftward in FIG. 1) on the road 11 while rotating when viewed from an observer on the road surface 11. . That is, the tire shape measuring apparatus 10 of the present invention can reproduce the state where the tire T travels on the road surface 11 while rotating.
The braking / driving means 13 includes a motor 13a whose output shaft is connected to the tire shaft J, and the magnitude of the driving force and the braking force applied to the tire shaft J by controlling the rotational speed and direction of rotation of the motor 13a. Is provided with slip rate control means 13b for controlling the slip rate of the tire T.

In the initial state, which is the state before the road surface 11 starts to move, the CCD camera 14 is located below the traveling portion 11a and photographs the tire T from the ground surface side. If the frame rate of the CCD camera 14 is 30 frames per second (30 fps), there is no problem in normal analysis. When it is desired to photograph the tire contact behavior at a high speed, a high speed camera may be used instead of the CCD camera 14.
The LED line light source 15 is attached to the lower side of the tempered glass plate G of the traveling part 11a serving as a transmission part and inside the frame 23a via a light source attachment member 15m.
In this example, since the light projecting means is configured to move together with the road surface 11, the entire tempered glass plate G of the traveling portion 11 a serving as a transmission portion that extends in the extending direction of the road surface 11, such as the LED line light source 15, is provided. A long light projecting means for uniformly projecting light is used. Further, the light irradiation angle is preferably set so that the incident angle is approximately 45 ° with respect to the tempered glass plate G, and thereby the entire traveling unit 11a can be illuminated with uniform brightness. At this time, it goes without saying that the LED line light source 15 is installed at a position where the LED line light source 15 is not reflected on the CCD camera 14.
Instead of the LED line light source 15, another light source such as a halogen lamp may be used. The point is that the amount of light can be adjusted, the amount of light during the test is stable, and the amount of light does not vary along the traveling portion 11a.
In the present invention, as described above, the entire traveling unit 11a is illuminated with uniform brightness. However, since there is actually light unevenness due to reflected reflection or the like, the color of the captured image is converted into a numerical value. Unevenness may occur. Therefore, in this example, as shown in FIG. 5 (a), a rubber sheet 35 of the same quality as the tire T is placed on the tempered glass plate G of the running portion 11a, and the image is taken by running in a pseudo manner without liquid. Photographing is performed, and color unevenness (unevenness in brightness) is corrected based on the captured image. Originally, since the tempered glass plate G is covered with a black rubber sheet, the entire road surface should be a complete grounding region. However, as shown in FIG. 5B, color unevenness occurs in the actually captured image. The dark part is the complete grounding area, and the bright part is the part where the light amount unevenness is large. Therefore, by mapping the brightness of the entire photographed image and performing difference processing from the actually photographed data, the light amount unevenness component can be removed and the measurement accuracy can be improved.

The moving means 16 includes two guide rails 161, a guide member 162, and a moving mechanism 163. The guide rail 161 is a member that extends in the front-rear direction, and is provided on each of the two rail holding bases 24 that extend in the front-rear direction and are installed on the base 21 at a predetermined interval. The guide member 162 is a block-like member that holds the road surface holding member 23, and travels in the front-rear direction on the guide rail 161 by the moving mechanism 163.
The moving mechanism 163 includes a ball screw 163a and a motor 163b. The output shaft of the motor 163b is connected to one end side of the screw shaft 163j of the ball screw 163a, and the nut portion 163n of the ball screw 163a is fixed to the guide member 162. Since the motor 163b is fixed on the motor mounting base 25 mounted on the base 21, the screw shaft 163j is rotated by the rotation of the motor 163b, and the nut portion 163n is moved in the front-rear direction, thereby maintaining the road surface. The road surface 11 attached to the guide member 162 via the member 23 moves in the front-rear direction.
The moving speed is controlled by accurate position control of the ball screw 163a, and the nut portion 163n of the ball screw 163a is fixed to the guide member 162. Therefore, even if a load, a longitudinal force, or a lateral force is generated on the tire T during the test. The movement of the guide member 162 is not affected.

The image processing unit 17 and the shape measuring unit 18 are configured by computer software, for example. The image processing means 17 obtains the luminance distribution of each pixel corresponding to the density distribution of the image taken by the CCD camera 14, and the shape measuring means 18 calculates the liquid L between the tire T and the tempered glass plate G from the luminance distribution. The depth of the liquid that is the depth of the tire is calculated, and the shape of the tire T is estimated from the depth of the liquid.
FIGS. 6A to 6C are diagrams illustrating an example of a photographed image when the tire T travels on the traveling portion 11a having a white colored water layer having a depth of 1 mm. FIG. 6A illustrates the driving force. (B) is a neutral state (free rolling state), and (c) is an image when a braking force is applied. The slip rate when the driving force is applied is -20%, and the slip rate when the braking force is applied is 20%. In each figure, the central white region P is a completely grounded region where water has not entered, and the region Q outside the region P is separated from the grounded surface (the liquid L between the tire T and the tempered glass plate G). A region indicating the shape of the tire T in a portion where the layer is present, and a region R outside the region Q is a region having water of 0.5 mm or more.
FIG. 7 is a diagram showing the tire shape at the shape cutout position AA in FIG. 6, and the horizontal axis is the position in the width direction of the traveling portion 11 a when the center in the tire width direction is the origin (y = 0). The vertical axis represents the liquid depth determined from the density of the image. A region P where the liquid depth is 0 mm is a complete grounding region. A region Q where the liquid depth is 0 mm to 0.5 mm is an image by reflected light near the ground contact surface of the tire T. In the region R, the tire T is not exposed to light.
Therefore, by connecting the liquid depth distribution in the tire width direction as shown in FIG. 7 along the tire front-rear direction by the shape measuring means 18, not only the contact length of the tire T but also the tire T in the vicinity of the tire contact surface. A three-dimensional shape can be obtained.
Further, by applying a braking / driving force to the tire shaft J, it is possible to measure a difference in tire shape due to a difference in slip rate.

Next, a method for measuring a tire shape using the tire shape measuring device 10 of the present invention will be described.
First, the white liquid L is put into a road surface pool constituted by the tempered glass plate G and the frame 19 of the traveling unit 11a by a predetermined depth, and calibration data is acquired. The calibration data is performed every time the depth of the liquid L (hereinafter referred to as water depth) is changed. Note that calibration data may be acquired for a plurality of water depths in advance.
And as shown to Fig.8 (a), the road surface 11 is set to the rear-end side (initial position) of the run-up part 11b which is the last end part of the advancing direction of a road surface. In this initial position, the cylinder rod 122a of the cylinder device 122 (not shown) is extended, and the tire T is grounded to the rear end side of the running portion 11b.
Next, the motor 163b of the moving mechanism 163 is driven to rotate the screw shaft 163j of the ball screw 163a, thereby moving the road surface 11 to the rear in the right direction in the figure. Since the tire T is rotatably attached to the tire holding means 12, it moves from the runway 11 in the direction of the slope 19k while rotating by friction with the road surface 11, and as shown in FIG. Land on the top surface of the tempered glass plate G.
The photographing of the tire ground contact surface by the CCD camera 14 and the measurement of the tire axial force are started when the tire T lands on the tempered glass plate G of the traveling portion 11a. At this time, it is assumed that a predetermined load is applied to the tire T by the cylinder device 122.
Due to the rotation of the screw shaft 163j of the ball screw 163a, the traveling portion 11a and the running portion 11b further move rearward on the right side of the drawing. That is, assuming that the traveling unit 11a is stationary, the tire T travels while rotating the traveling unit 11a at the water depth forward.
The CCD camera 14 photographs the ground surface of the tire T and the vicinity of the ground surface from the opposite side of the tire T of the transparent tempered glass plate G with the tire T running while rotating. In this example, since the LED line light source 15 is provided over the entire length of the tempered glass plate G of the traveling part 11a which is a transmission part, the entire traveling part 11a can be illuminated with uniform brightness.
And as shown in FIG.8 (c), imaging | photography is complete | finished when the tire T advances to the front-end part of the road surface 11, and the movement of the road surface 11 is stopped.
Data of an image photographed by the CCD camera 14 is sent to the image processing means 17, and the luminance distribution of each pixel of the image is obtained by the image processing means 17. The shape measuring means 18 calculates the liquid depth from the luminance distribution and measures the three-dimensional shape of the tire T.
As a result, the tire ground contact surface and the shape in the vicinity of the ground contact surface, which could only be measured at one point or one line at the same time, can be measured simultaneously, so the tire shape and the ground contact state during traveling can be accurately measured. In addition, since the tire axial force can be measured at the same time, it is possible to consider the relationship between the change in the tire axial force, the ground contact characteristics, and the tire shape. Furthermore, since the amount of water that has entered the tire contact surface can also be measured, the WET characteristics of the tire can also be considered.

  As described above, in the present embodiment, the tire T is grounded on the transparent tempered glass plate G constituting the traveling portion 11a of the road surface 11, and the white liquid L is added to the road surface pool provided on the surface of the tempered glass plate G. The side where the tire T of the tempered glass sheet G contacts the ground while moving the guide member 162 holding the road surface 11 along the guide rail 161 in the front-rear direction by rotating the ball screw 163a of the moving mechanism 163. Since the shape of the tire T traveling in the liquid L is photographed by the CCD camera 14 provided on the opposite side, and the shape of the tire T is measured from the photographed image, the tire T travels while rotating. It is possible to accurately measure the state of the ground contact surface and the deformation state of the tire near the ground contact surface. In addition, since the amount of liquid entering the tire contact surface and the shape of the tire portion immersed in the liquid can be accurately measured, it is possible to accurately grasp the running state of the tire on the WET road.

In the embodiment, a smooth tire without a tread pattern is used as the tire T. However, if a tire having a tread pattern formed on the tread surface is used, a portion corresponding to the groove and a portion immersed in water. Since the brightness of the reflected light decreases, the white area P in the center of FIGS. 6A to 6C becomes a gray image corresponding to the tread pattern. In addition, since the portion that is immersed in water appears on the image as a shade corresponding to the depth of the liquid (liquid depth) that has entered, it is possible to accurately measure the tread pattern deformation state and fluid intrusion amount in the ground plane. can do.
In the above example, the white liquid L is introduced into the road surface pool and the shape of the tire contact surface is measured. However, if only the shape of the contact surface during DRY road measurement is measured, the road surface pool and the liquid L are used. It may be omitted. Thereby, it is possible to measure the shape of the tire ground contact surface when traveling on the DRY road while rotating the tire T, which could not be measured conventionally.
Moreover, in the said example, although all the traveling parts 11a were comprised with the transparent tempered glass, when a road surface width can be taken widely, only the width direction center is comprised with a transparent tempered glass, and the width direction outer side is comprised with a metal plate etc. It may be configured. However, the width of the tempered glass portion is preferably 2 to 5 times the tire width of the tire T to be tested.
Moreover, when making the road surface 11 long, you may make it the structure which joined the tempered glass and the metal plate alternately in the front-back direction. In this case, since the role of the metal plate is to connect adjacent tempered glasses, the length in the front-rear direction is preferably as short as possible.

Moreover, if a mechanism for imparting a slip angle or a camber angle to the tire T is added to the tire shape measuring apparatus 10 having the above-described configuration, the tire shape when a lateral force is input can also be measured. In order to provide the slip angle, for example, the extending direction of the horizontal frame 22b protruding in the horizontal direction of the mounting frame 22 is inclined with respect to the tire width direction, or the base 21 is rotated in a horizontal plane to extend the road surface 11 May be inclined with respect to the front-rear direction of the tire. On the other hand, in order to provide the camber angle, for example, the angle at which the tire shaft J is attached to the tire support member 121 may be changed.
Practically, it is sufficient that the slip angle can be given up to about ± 10 °, and the camber angle can be given up to about ± 5 °.

In the above example, the ball screw 163a is used as the moving mechanism 163, but other moving mechanisms such as a linear actuator and a rack and pinion mechanism may be used.
In the above example, the road surface 11 is moved. However, the road surface 11 may be fixed and the tire T and the CCD camera 14 may be moved.
Moreover, as shown to Fig.9 (a), it is good also as a structure which fixed the LED line light source 15s which is a light projection means to the base 21 via the light source fixing member 15n. In this case, as long as the LED line light source 15s is long enough to cover the photographing range of the CCD camera 14 as shown in FIGS.

The tire shape was measured using the tire shape measuring apparatus according to the present invention.
The runway used was a transparent tempered glass plate having a length of 2000 mm, a width of 800 mm, and a thickness of 50 mm, and the tempered glass plate was fixed to a resin frame via a rubber layer. In addition, the interface between the resin and the glass plate was bonded with an adhesive, and a caulking process was performed to prevent water leakage. The resin frame is obtained by integrating the frame body 19 and the road surface holding member 23 of the embodiment.
The width of the runway was 800 mm, the same as the width of the road, and the length was 1 m.
And the runway and the approach runway were fixed to the metal guide member installed on the guide rail of length 8m.
A ball screw having a length of 8 m is installed on the guide member, and the screw shaft of the ball screw rotates to the motor. In this embodiment, the road surface is run in the range of 0 to 10 m / min.
The CCD camera was installed 1 m below the tempered glass plate, just below the center axis of the tire axis. Shooting was performed at 30 frames per second (30 fps).
In a road surface pool surrounded by a resin frame and tempered glass, water colored by adding a pigment to distilled water to give a white water depth was 1 mm, and calibration data was acquired before the test. The method for acquiring calibration data is as described in the embodiment.
As the test tire, a smooth tire having no pattern of 195 / 65R15 was used.
The air pressure of the test tire was 200 kPa, the load was set to 4 kN, and both the slip angle and the camber angle were 0 °.
The tire shape measurement test was carried out with the road speed set at a constant condition of 5 m / min and with the slip rate varied between 0 and ± 20%.
At the same time as shooting, the tire axial force was measured with a partial pressure gauge.
As a result of the measurement, the generated longitudinal force was 1 kN with respect to a load of 4 kN. The road surface μ was about 0.25.
The tire shape at this time is as shown in FIGS.
The tire shape can be cut out into arbitrary parts, and a part thereof is as shown in FIG.
As shown in FIGS. 6A to 6C, when a braking force is applied to the tire, a backward force acts on the tire in the traveling direction, the ground contact surface moves rearward, and a driving force is applied. Then, conversely, it can be seen that the ground plane moves forward.
Thus, it was confirmed that the tire shape and the ground contact state can be accurately measured by using the tire shape measuring device according to the present invention.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the embodiment. It is apparent from the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  According to the present invention, since the surface shape of the tire including the contact surface shape and the vicinity of the contact surface when the tire is running can be accurately measured, in order to improve the tire performance including the tire movement performance Effective design materials can be provided.

10 tire shape measuring device, 11 road surface, 11a traveling part, 11b running part,
12 tire holding means, 121 tire support member, 122 cylinder device,
123 component force meter, 13 braking / driving means, 13a motor, 13b slip ratio controlling means,
14 CCD camera, 15 LED line light source, 15m light source mounting member,
16 moving means, 161 guide rail, 162 guide member, 163 moving mechanism,
163a Ball screw, 163b motor, 17 image processing means,
18 shape measuring means, 19 frame, 19a to 19d wall, 19k slope,
21 base, 22 mounting frame, 23 road surface holding member, 23a frame,
23b support piece, 24 rail holding base, 25 motor mounting base,
T tire, J tire shaft, G tempered glass plate, L liquid.

Claims (5)

Tire holding means for holding the tire rotatably;
A road surface extending at least in the front-rear direction of the tire, wherein at least a portion where the tire contacts the ground includes a transmission portion made of a material that transmits light;
An imaging means for photographing the shape of the tire installed on the side opposite to the side where the tire contacts the ground of the transmission part;
A light projecting means installed on the same side as the imaging means to irradiate the tire with light;
Image processing means for calculating the luminance data of each pixel by image processing the tire image taken by the imaging means;
Shape measuring means for measuring the shape of the tire from the calculated luminance data;
A tire shape measuring apparatus comprising: a moving means for moving the road surface relative to the tire and the imaging means in the front-rear direction of the tire.   A frame provided on a tire side of the road surface, and a liquid that is stored in a space formed by the road surface and the frame and that forms a liquid layer on the upper surface of the transmission portion. Item 2. The tire shape measuring device according to Item 1.   The tire shape measuring device according to claim 2, wherein the liquid is a white liquid or a liquid colored in white.   The tire shape measuring device according to any one of claims 1 to 3, further comprising a mechanism that applies one or both of a braking force and a driving force to the tire. The tire is grounded on a transparent plate, the tire is irradiated with light from the opposite side of the transparent plate to the side where the tire is grounded, and the shape of the tire is photographed. From the photographed image, the shape of the tire is photographed. In the tire shape measuring method for measuring
While holding the tire rotatably, a liquid layer made of a white liquid or a liquid colored in white is provided on the surface of the transparent plate, while moving the transparent plate in the front-rear direction of the tire A tire shape measuring method comprising photographing a tire shape.

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