Jig used for calculating tire center line and method for calculating tire center line

Abstract

To provide a method for calculating the tire center line of a vehicle, the method capable of performing accurate measurement.SOLUTION: Two types of jigs are used: a jig fixed to a brake disk surface of a wheel; and a jig fixed to a wheel center. A target seal used for positional information measurement is applied to each jig. The position of the jig to which such a target seal is applied is converted into a three-dimensional state through photogrammetry. A tire center surface is calculated from the calculated brake disk surface. A tire center point is calculated from such a tire center surface. Wheel bases, treads and the like are calculated from four tire center points for one vehicle, and thereby the accurate tire center lines, wheel bases, treads, and the like can be calculated without being affected by a camber and the like.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a method for calculating the center line of a tire used for a vehicle and a jig used for the method.

Background Art

[0002] In the process of manufacturing an automobile vehicle, as one of the precision extraction inspections based on the specified automobile management regulations, there is a process of measuring the overall length, overall height, etc. of the vehicle. In the measurement of the wheelbase (axle distance), tread (track width), etc. in such a process, it is common to measure the center line of the tire, which is the center part of the tire, and calculate the wheelbase, tread, etc. based on the measured center line.

[0003] And, as the prior art of such a tire center line measurement method, there are a method of sandwiching the tire with a measuring device to measure the tire center line (Patent Document 1, Patent Document 2), a method of irradiating the tire with laser light from near the tire for non-contact measurement of the tire center line (Patent Document 3), etc.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the conventional tire center line measurement methods have some deficiencies in the accuracy of calculating the tire center line. Specifically, in the measurement methods described in Patent Document 1 and Patent Document 2, since the tire is directly clamped by the measuring device to measure the tire center line, it may be affected by the camber or the air pressure of the tire. Therefore, a more accurate method for measuring the tire center line that is less affected by the air pressure of the tire is required.

[0006] Also, in the measurement method described in Patent Document 3, since the laser light is irradiated on the tire to directly measure the tire center line, it may be affected by the air pressure of the tire or the like.

[0007] The present invention has been made in view of the above problems, and an object thereof is to provide a jig used for calculating the tire center line and a method for calculating the tire center line that can accurately calculate the tire center line.

Means for Solving the Problems

[0008] The present invention is a jig used for calculating the tire center line that can be fixed to the wheel center of a vehicle tire, and has an upper cylindrical portion and a lower cylindrical portion provided below the upper cylindrical portion. A target display portion used for measuring position information is provided on the upper surface portion forming the upper surface of the upper cylindrical portion and on the outer peripheral surface portion of the upper cylindrical portion. An identification display portion for identifying the spatial position of the jig is provided on the upper surface portion. A magnet for the purpose of fixing to the wheel center is disposed at the edge of the lower cylindrical portion. It is a jig used for calculating the tire center line, characterized in that.

[0009] The present invention also relates to a jig used for calculating the tire center line to be inserted between the spoke portions of the wheel portion of a vehicle tire, which has a main body portion as the head portion and a support rod portion having one end connected to the bottom surface portion of the main body portion. A target display portion for measuring position information is provided on the side surface portion of the main body portion, and an identification display portion for identifying the jigs inserted between the spoke portions is provided on the upper surface portion of the main body portion. A magnet for fixing to a brake disk provided inside the wheel portion is disposed on the end surface portion of the other end side of the support rod portion. It is a jig used for calculating the tire center line, characterized by the above.

[0010] The present invention also relates to a method for calculating the tire center line using these jigs, with the jig according to claim 1 as the first jig and the jig according to claim 2 as the second jig. The method includes the steps of fixing the first jig to the wheel center of the vehicle, inserting three or more of the second jigs between the spoke portions of the wheel portion and fixing the second jig to the brake disk, calculating the position information of the two types of jigs, the first jig and the second jig, by a surveying method that represents the position information such as photogrammetry as a three-dimensional diagram and calculating the three-dimensional coordinates, calculating a center line passing through the center of the first jig as the wheel center line from the position information of the first jig, calculating the brake disk surface of the brake disk from the position information of the second jig, and offsetting the calculated brake disk surface so as to pass through the tire center portion to calculate the tire center plane. It is a method for calculating the tire center line, characterized by including the above steps.

Advantages of the Invention

[0011] According to the tire center line calculation method according to the present embodiment, by using two types of jigs, a spindle jig and a brake disk jig, to calculate the tire center line, it is possible to calculate the tire center line more accurately than the prior art.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0013] In this embodiment, two types of jigs are used: a jig fixed to the brake disk surface of the wheel and a jig fixed to the wheel center. A target seal for measuring position information is attached to each jig, and the position of the jig to which such a target seal is attached is three-dimensionally measured by photogrammetry. The tire center plane is calculated from the calculated brake disk surface, the tire center point is calculated from such a tire center plane, and the wheelbase, tread, etc. are calculated from the tire center points of the four tires of one vehicle, thereby enabling accurate calculation of the tire center line, wheelbase, tread, etc. without being affected by camber or the like.

[0014] First, regarding the measurement target location in the present embodiment, it will be described with reference to FIGS. 1, 4, and 5. As shown in FIG. 1, the tire 50 according to the present embodiment is a wheel of a vehicle such as an automobile, and includes a wheel portion 22 and a rubber tire portion 21 fitted around the wheel portion 22. The wheel portion 22 includes a wheel center 24 and spoke portions 23 radially arranged from the wheel center 24. Further, a brake disk 31 is provided inside the wheel portion 22 of the tire 50 (inside in the left-right direction in the vehicle).

[0015] In the present embodiment, after calculating the position of the brake disk surface 31a, which is the plate surface on the outer side (outer side in the left-right direction in the vehicle) of the brake disk 31 inside the wheel portion 22 of the tire 50, the calculated brake disk surface 31a is offset to the tire center portion, and based on such offset brake disk surface 31a, the tire center point indicating the point that bisects the width of the tire 50 is measured. Then, based on the positions of such tire center points regarding the four tires 50 of one vehicle, the front tread, rear tread, wheelbase, etc. are calculated (FIGS. 5(a), (b), (c)).

[0016] Also, in the present embodiment, in order to enable accurate calculation of the tire center line, when calculating the tire center line, after calculating the brake disk surface 31a inside the tire, the calculated brake disk surface 31a is offset to calculate the tire center line. The brake disk 31 has a disk-shaped flat disk-like structure, is disposed inside the wheel portion 22 of the tire 50, and can directly touch the brake disk 31 behind the spoke portions 23 from the gaps between the spoke portions 23 of the wheel portion 22 (FIG. 1).

[0017] [1. Fixture used in the method for calculating the tire center line] Next, the fixture used in the method for calculating the tire center line according to the present embodiment will be described based on FIGS. 2 and 3. In this calculation method, mainly two types of fixtures, a first fixture and a second fixture, are used.

[0018] First, the spindle jig 5, which is the first jig, will be described with reference to FIG. 2. The spindle jig 5 is a jig that is fitted into the wheel center 24 of a tire and used to calculate the wheel center line. Such a spindle jig 5 is made of a metal such as steel, for example, but the type of material is not limited as long as it can be similarly fitted and used.

[0019] Such a spindle jig 5 is divided into two regions: an upper cylindrical portion 3 and a lower cylindrical portion 4. It has an upper cylindrical portion 3 and a lower cylindrical portion 4 provided below the upper cylindrical portion 3. The spindle jig 5 is a member having a cylindrical outer shape as a whole. Most of the lower side of the spindle jig 5 is the cylindrical lower cylindrical portion 4, and above the lower cylindrical portion 4, an upper cylindrical portion 3, which forms the upper end portion of the spindle jig 5 and is a diameter-expanded portion with respect to the lower cylindrical portion 4, is provided. The upper cylindrical portion 3 and the lower cylindrical portion 4 are provided so that the central axes in the cylindrical shape coincide with each other, and the spindle jig 5 has a rotating body shape.

[0020] The upper cylindrical portion 3 has a height of approximately 10 mm and a diameter of approximately 60 mm. On the other hand, the lower cylindrical portion 4 has a height of approximately 50 mm and a diameter of approximately 50 mm, and the diameter of the upper cylindrical portion 3 is slightly larger than the diameter of the lower cylindrical portion 4. However, regarding the aspect of the diameter of the upper cylindrical portion 3 and the diameter of the lower cylindrical portion 4, it does not matter which is larger or smaller. That is, the upper cylindrical portion 3 may have a smaller diameter than the lower cylindrical portion 4, or the upper cylindrical portion 3 and the lower cylindrical portion 4 may have the same diameter. And the internal space portion of the lower cylindrical portion 4 becomes a cylindrical cavity 6 downward and has a lower open structure. And the lowermost end portion of the lower cylindrical portion 4 becomes a lower surface portion 4a that forms the opening end face of the cavity 6, and at least one or more magnets 7 are disposed on such a lower surface portion 4a (FIG. 2(b)).

[0021] The magnet 7 is for fixing the spindle jig 5 to the wheel center 24. The magnet 7 is provided in a state of being fitted into a recess formed in the lower surface portion 4a of the lower cylindrical portion 4, and is provided so as not to protrude from the lower end surface perpendicular to the central axis of the lower cylindrical portion 4. The plurality of magnets 7 are arranged at appropriate intervals along the circumferential direction of the lower surface portion 4a. At least one or more magnets 7 are arranged. Regarding the arrangement configuration of the magnets 7, for example, a configuration in which one ring-shaped magnet 7 corresponding to the diameter of the lower surface portion 4a may be arranged.

[0022] The upper cylindrical portion 3 has an upper surface portion 3a forming an upper surface along a plane perpendicular to the central axis of the spindle jig 5, and an outer peripheral surface portion 3b forming a cylindrical surface. The upper surface portion 3a of the upper cylindrical portion 3 becomes the upper end surface portion of the spindle jig 5. Further, the lower cylindrical portion 4 has a lower surface portion 4a forming an upper surface along a plane perpendicular to the central axis of the spindle jig 5, and an outer peripheral surface portion 4b forming a cylindrical surface. The lower surface portion 4a of the lower cylindrical portion 4 becomes the lower end surface portion of the spindle jig 5.

[0023] Also, a large number of target seals 1 as target display portions for use in position information measurement are attached to the upper surface portion 3a and the outer peripheral surface portion 3b forming the upper surface of the upper cylindrical portion 3 of such a spindle jig 5. Such target seals 1 are attached to the upper surface portion 3a at about 10 pieces at appropriate intervals along the circumferential direction near the outer peripheral edge, and to the outer peripheral surface portion 3b at about 10 pieces at equal intervals or substantially equal intervals in the circumferential direction, but any mode is acceptable as long as data necessary for calculation can be collected.

[0024] In the present embodiment, the target seal 1 displays a circular shape. However, the shape displayed by the target seal 1 is not limited to a circular shape, and may be, for example, a polygon such as a triangle or a quadrilateral, or a star shape. Further, the target display portion is provided by attaching the target seal 1, but is not limited to such a configuration. The target display portion may be provided by a method other than attaching a seal, such as painting at a predetermined location on the spindle jig 5.

[0025] Also, a identification label 2 as an identification display portion for distinguishing from other jigs is attached to the upper surface portion 3a of the upper cylindrical portion 3. The identification label 2 is attached to the central portion of the upper surface portion 3a of the upper cylindrical portion 3, and is provided in a region surrounded by a group of target labels 1 disposed at the peripheral portion on the upper surface portion 3a.

[0026] In the present embodiment, the identification display portion is provided by attaching the identification label 2, but is not limited to such a configuration. The identification display portion may be provided by a method other than attaching a label, for example, by painting a predetermined location on the spindle jig 5.

[0027] An embodiment in using such a spindle jig 5 will be described with reference to Fig. 4. When using such a spindle jig 5, it is fitted into the cavity inlet portion of the wheel center 24 from the lower cylindrical portion 4 side of the spindle jig 5 (if there is a wheel emblem, it is removed in advance, and the spindle jig 5 is inserted and fixed into the cavity portion where the wheel emblem existed). Then, it is fixed to the wheel center 24 portion via a magnet disposed on the lower surface portion 4a of the spindle jig 5. In such a state where the spindle jig 5 is fixed to the wheel center 24, position information measurement is performed (Fig. 4(a), (b)).

[0028] Next, with reference to Figs. 3 to 5, a brake disk jig 12 which is a second jig will be described. The brake disk jig 12 is fitted and used between the spokes 23 of the wheel portion 22 of the tire (Fig. 4(a), (b)). Such a brake disk jig 12 is made of a metal such as steel, for example, but the type of its material is not limited as long as it exhibits the same operational effects.

[0029] Such a brake disk jig 12 is composed of a main body 10 having a rectangular parallelepiped outer shape and a columnar bar portion 11 which is a support bar portion with one end connected to the bottom surface portion of the main body 10 (Fig. 3(a)). And, the columnar bar portion 11 is welded and joined to one surface constituting the main body 10, and the surface portion of the main body 10 to which such columnar bar portion 11 is joined is hereinafter referred to as the main body bottom surface portion 10c, the opposite surface as the main body upper surface portion 10a, and the other four surfaces as the main body side surface portions 10b. Note that although the main body 10 in the present embodiment has a rectangular parallelepiped shape, its shape is not limited to a rectangular parallelepiped. Specifically, the shape of the main body 10 may be a cylindrical shape or the like. Further, the connection method between the aforementioned main body 10 and the columnar bar portion 11 is not limited to a welding method. Specifically, for example, as an aspect, while leaving a rectangular parallelepiped portion as the main body 10 from a prismatic material, the columnar bar portion 11 may be formed by lathe processing. In this case, the main body 10 and the columnar bar portion 11 will be formed of an integral member. As another example, a rectangular parallelepiped part forming the main body 10 and a columnar part forming the columnar bar portion 11 may be formed, screw portions may be provided on each part, and the parts may be integrated by screw engagement with each other.

[0030] The main body 10 of such a brake disk jig 12 is a structure with a length of approximately 3 cm, a width of approximately 3 cm, and a height of approximately 4 cm. And, target seals 1 for position measurement are affixed to the four side surface portions of such main body side surface portions 10b. The number of such target seals 1 affixed is approximately 6 per surface and is affixed to all three side surface portions, but the number of affixed seals is not limited as long as data necessary for calculating the tire center line can be collected. Further, an identification seal 2 for distinguishing from other jigs is affixed to the main body upper surface portion 10a of such main body 10.

[0031] Further, the columnar bar portion 11 has a structure with a length of approximately 100 mm and a diameter of approximately 10 mm. One end portion of such columnar bar portion 11 is joined to the main body bottom surface portion 10c, and the other end portion of the columnar bar portion 11 extends from the main body bottom surface portion 10c. This end portion becomes a columnar bar lower end portion 11a forming the lower end surface on the annular ring. A magnet 13 is embedded in the bottom surface portion of the columnar bar lower end portion 11a, and such a portion has magnetic force (Fig. 3(b)).

[0032] The magnet 13 is for fixing the brake disk jig 12 to the brake disk surface 31a. The magnet 13 has a circular outer shape and is provided in a state of being fitted into a circular recess or hole that opens facing the bottom surface of the lower end portion 11a of the columnar rod portion. It is provided so as not to protrude from the lower end surface perpendicular to the central axis of the columnar rod portion 11. Although there is one magnet 13 in the present embodiment, it may be configured in a manner such as providing a plurality of small magnets.

[0033] And when using such a brake disk jig 12, it is inserted between the spoke portions 23 of the wheel portion 22 from the lower end portion 11a of the columnar rod portion. Then, it is inserted until it contacts the brake disk 31 inside the wheel portion 22, and the brake disk jig 12 and the brake disk 31 are fixed via the magnet on the surface of the lower end portion 11a of the columnar rod portion. Three such brake disk jigs 12 are used for each wheel for measuring the surface of the brake disk 31. And position information measurement is performed by the target seal 1 attached to the side surface portion 10b of the main body portion of such a brake disk jig 12, and the brake disk surface 31a is calculated from the calculated position information of the target seal.

[0034] The features of the brake disk jig 12 according to the present embodiment are as follows. Specifically, this brake disk jig 12 has a columnar rod portion 11 that is inserted between the spoke portions 23 of the wheel portion 22, and secures a main body portion 10 to which a sufficient number of target seals 1 can be attached for calculating measurement data.

[0035] Further, such a brake disk jig 12 has a rectangular parallelepiped-shaped main body cavity portion 10d that is recessed or opened inside on one of the four side surface portions 10b of the main body portion 10 of the brake disk jig 12 (FIG. 3(c)). Such a main body cavity portion 10d is formed for the purpose of reducing the weight of the brake disk jig 12. When inserting and fixing the brake disk jig 12 between the spoke portions 23 of the wheel portion 22 and performing position information measurement, by disposing such a main body cavity portion 10d, it is possible to prevent the brake disk jig 12 from coming off and falling due to its own weight.

[0036] Further, in such a brake disk jig 12, a magnet is disposed at the lower end portion 11a of the columnar rod portion thereof. Therefore, the coupling property with the brake disk 31 is excellent, and it can be easily removed at the end of measurement.

[0037] Also, in the present embodiment, the target seal 1 shows a circular shape. However, the shape shown by the target seal 1 is not limited to a circular shape, and may be, for example, a polygon such as a triangle or a quadrilateral, or a star shape. Further, the target display portion is provided by attaching the target seal 1, but is not limited to such a configuration. The target display portion may be provided by a method other than attaching a seal, such as painting at a predetermined location on the brake disk jig 12.

[0038] Also, on the upper surface portion 10a of the main body portion 10, one identification seal 2 as an identification display portion for distinguishing from other jigs is attached. The identification seal 2 is attached over the entire upper surface portion 10a of the main body portion 10a in the upper surface portion of the main body portion.

[0039] In the present embodiment, the identification display portion is provided by attaching the identification seal 2, but is not limited to such a configuration. The identification display portion may be provided by a method other than attaching a seal, such as painting at a predetermined location on the brake disk jig 12.

[0040] Next, the surface plate reference jig 20 will be described with reference to FIGS. 4 and 5. The surface plate reference jig 20 is a jig for accurately measuring the surface plate 32 which is the ground surface. Such surface plate reference jigs 20 are arranged one by one in the vicinity of each of the four vehicle tires, for a total of four (FIG. 4(a)). A plurality of the above-mentioned target seals 1 are respectively attached to such four surface plate reference jigs 20, and when calculating the position information of the above-mentioned spindle jig 5, brake disk jig 12, etc., the position information of the target seal 1 attached to such surface plate reference jig 20 is also calculated simultaneously. Then, based on the position information of the four surface plate reference jigs 20, it is possible to calculate the accurate ground surface on which the vehicle is placed.

[0041] Next, the target seal 1 will be described. As described above, a large number of target seals 1 are attached to each jig and are used for calculating the position information. Such target seal 1 must be within the captured image when analyzed by the three-dimensional measuring device. Therefore, at least one or more target seals 1 attached to each jig are attached in a larger amount within the possible range of one jig so that they are reflected in the captured image. Then, after imaging with the high-resolution camera used for measurement, the position information of the target seal 1 is measured, and the brake disk surface 31a, etc. are calculated based on such position information.

[0042] Next, the identification seal 2 will be described. As described above, one identification seal 2 is attached to each of the fixtures such as the upper surface portion 3a of the upper cylindrical portion 3 and the upper surface portion 10a of the main body portion, one for each fixture. The identification seal 2 has a black square background with a white circular ring drawn thereon, and a white perfect circle is drawn concentrically with the circular ring inside. And a part of such white circular ring is painted black and has a missing shape, and the identification seal 2 has a different shape for each, depending on the difference in the part missing due to the black painting of the circular ring. The mode of forming a mark by the white and black colors of the identification seal 2 may also be configured by a combination of other colors. That is, the criterion for recognizing the difference in shape in the identification seal 2 is the contrast difference between the two colors in the identification seal 2, and is not limited to the combination of white and black. And due to the shape difference, it is possible to discriminate the position of each fixture, such as whether the fixture to which the identification seal 2 is attached is connected to the front tire or the rear tire, or to which of the left and right tires it is connected. Also, the white circular portion at the center of the identification seal 2 functions as the identification seal 2 and becomes a part of a shape different from that of the corresponding part of other identification seals 2, and also functions as the target seal described above, and also plays a role of allowing the high-resolution camera to recognize the position information.

[0043] [2. Principle and Procedure of Tire Center Line Calculation Method According to the Present Embodiment] Next, the tire center line calculation method according to the present embodiment will be described.

[0044] First, the principle of the calculation method according to the present embodiment will be explained. In this calculation method, a three-dimensional measurement technique using a DPA (Digital Photogrammetric Analysis) system as an example is utilized. Such a three-dimensional measurement technique is a three-dimensional surveying method that calculates the three-dimensional coordinates of the uneven shape of an article by attaching a target seal 1 to the article, then using a high-resolution digital camera to photograph the article from various angles, digitizing the position information of the target seal 1 based on the photographed data, and representing it three-dimensionally. And the measurement position information is calculated from the target seal 1 attached to the article or the like.

[0045] Theoretically, if there are any three points that are not on the same straight line, the plane passing through these three points is limited to only one. In this embodiment, since the brake disk surface 31a is calculated from measurement data and the tire center line is calculated based on such measurement data, for the brake disk jig 12 for measuring the brake disk surface 31a, three are sufficient for one wheel (the brake disk jig 12 for measuring the brake disk surface 31a can calculate the brake disk surface 31a accurately enough with three).

[0046] Next, the specific implementation procedure of the method for calculating the tire center line according to this embodiment will be described with reference to FIGS. 4 to 7. First, the aforementioned spindle jig 5 and brake disk jig 12 are attached to the wheel portion 22 (step S1). The target wheel portion 22 is all the wheel portions 22 connected to the four tires 50 of one vehicle (FIG. 4(a)). First, from both the left and right sides of the vehicle toward the inside of the vehicle, the spindle jig 5 is fitted into the wheel center 24 of the wheel portion 22, and the spindle jig 5 is fixed by the magnetic force of the magnet 7. At this time, it is inserted into the wheel center 24 from the lower cylindrical portion 4 of the spindle jig 5, and the upper cylindrical portion 3 is fixed without fitting into the wheel center 24. That is, the upper cylindrical portion 3 is located outside the cavity inlet portion of the wheel center 24, and the upper surface portion 3a and the outer peripheral surface portion 3b are in an exposed state.

[0047] Also, three or more brake disk jigs 12 are inserted between the spoke portions 23 of the wheel portion 22 for one wheel (step S1). At this time, it is inserted between the spoke portions 23 from the cylindrical rod portion 11 of the brake disk jig 12 until it contacts the internal brake disk surface 31a. Since a magnet 13 is disposed at the lower end portion 11a of the cylindrical rod portion of the cylindrical rod portion 11 of the brake disk jig 12, when the surface of the lower end portion 11a of the cylindrical rod portion of the cylindrical rod portion 11 is close to the brake disk surface 31a, the lower end portion 11a of the cylindrical rod portion and the brake disk 31 are fixed by magnetic force (FIGS. 4(a) and (b)).

[0048] Furthermore, four surface plate reference jigs 20 are arranged near the ground in the vicinity of the four tires of a vehicle (step S1, FIG. 6). There is no problem as long as such a surface plate reference jig 20 is in the vicinity of the tire.

[0049] After arranging each jig as described above, photographing is performed with a high-resolution camera (step S2). In such a process, photographing is performed from multiple angles so as to surround a vehicle. The number of such photographs is, for example, about 180 for one round of the vehicle. Also, a reference scale serving as a length reference is arranged at the rear of the photographing vehicle, and the part at the time of photographing is also photographed simultaneously. Then, based on such a reference scale, the length and the like of the object in the three-dimensional data are calculated. Then, the position information data of each jig is imported into analysis software (step S3), and a three-dimensional diagram of the target vehicle, target tires, etc. is created from the position information data of each jig (step S4). Here, by using the technique of known photogrammetry (photogrammetric method), three-dimensional coordinates are calculated from a plurality of photographs taken by a camera, and a three-dimensional model is created. In this way, by the surveying method of calculating three-dimensional position information by photogrammetry, the position information of two types of jigs, the spindle jig 5 and the brake disc jig 12, is calculated and three-dimensionalized.

[0050] Using the position information (three-dimensional position information) of the spindle jig 5, the brake disk jig 12, and the surface plate reference jig 20, the following information is calculated and set. That is, first, using the four surface plate reference jigs 20, the surface plate 32 is calculated (step S4). The surface plate 32 refers to the surface on which the vehicle is placed. That is, a more accurate surface on which the vehicle is placed is calculated considering the inclination of the ground surface and the like. Next, the wheel center line 33 is calculated from the measurement data of the spindle jig 5 (step S4). The wheel center line 33 refers to the extension line of the center line of the spindle jig 5 and is a line passing through the center of the wheel. Then, the brake disk surface 31a is calculated from the three brake disk jigs 12 (step S4). The method for calculating such a brake disk surface 31a is to calculate a plane passing through three points from the position information of the three brake disk jigs 12, and then correct by the distance from the position of the target seal 1 of the brake disk jig 12 to the lower surface portion 4a of the brake disk jig 12, which is the portion where the brake disk 31 is connected, and calculate the surface where the brake disk 31 originally exists within the tire 50 as the brake disk surface 31a (step S4).

[0051] Then, the calculated brake disk surface 31a is offset to the center portion of the tire to calculate the tire center plane 30 (FIG. 7, step S5). Specifically, referring to the distance between the brake disk 31 and the center portion of the tire from the drawing or the like, the brake disk surface 31a is translated in the direction parallel to the central axis of the tire 50 by that difference. Here, the "center portion of the tire" is the central position in the central axis direction (width direction) of the tire 50. Then, by translation, the cross-section of the tire (brake disk surface 31a) passing through the center portion of the tire is calculated as the tire center plane 30 (FIG. 5(a)). Since the brake disk surface 31a is inclined at the same angle as the tire 50 with respect to the camber of the tire 50, an accurate tire center plane that is not affected by the camber can be calculated by such a calculation method. Also, if the difference in the inclination angle between the brake disk surface 31a and the tire 50 is known from the drawing data, such a difference is considered at the time of offset for calculation.

[0052] Then, the intersection point of the wheel center line 33 and the tire center plane 30 is calculated as the tire center plane center point 34 (step S6, Fig. 5(b)). Then, a perpendicular line passing through such a tire center plane center point 34 and perpendicular to the surface plate 32 is drawn, and a provisional point 35 that is the intersection point of such a perpendicular line and the surface plate 32 is set (step S6, Fig. 5(b)). Such a provisional point 35 is set for the left tire and the right tire, the provisional points 35 of the left tire and the right tire are connected by a straight line, and the intersection point of the line extended on the left and right extension lines of such a straight line and the tire center plane 30 is calculated as the tire center point 36 (step S7, Fig. 5(c)).

[0053] And by such steps, the tire center point 36 is calculated for each of the four tires (step S7). Using the calculated tire center point 36, the tread, wheelbase, etc. are calculated (step S8).

[0054] The method for calculating the tread and wheelbase based on the tire center point in step S8 is as described in Figs. 5(d) and 5(e). That is, the distance between the tire center points 36 on both the left and right sides of the front tire is measured as the front tread, and the distance between the tire center points 36 on both the left and right sides of the rear tire is measured as the rear tread (Fig. 5(d)). Also, the distance between the center points of the front tread and the rear tread is calculated as the wheelbase (step S8, Fig. 5(e)).

[0055] [3. Operational Effects of the Tire Center Line Calculation Method According to the Present Embodiment] According to the tire center line calculation method according to the present embodiment, the following operational effects can be obtained.

[0056] In the tire center line calculation method according to the present embodiment, an attachment such as the spindle jig 5 is attached to the wheel portion 22 of the tire 50 of the vehicle, and the position information data is analyzed by software to calculate the tire center line. Therefore, compared with the conventional technology in which the tire center line is measured by causing the vehicle to draw a tire trace line, the labor of the operator for measurement is less, and it is excellent in safety.

[0057] Moreover, in the tire center line calculation method according to this embodiment, since the spindle jig 5 and the brake disk jig 12 as attachments are mounted on the wheels of the vehicle and the measurement data is only analyzed by software, the working time is short, and as a result, the working efficiency is improved. Specifically, in the method of having the vehicle draw a tire trace line and calculating the tire center point from such a trace line, the working time that required two workers and took about 200 minutes can be completed in about 40 minutes with only one worker by the measurement method according to this embodiment.

[0058] Moreover, in the tire center line calculation method according to this embodiment, compared with the physical measurement method using a ruler or the like in the prior art, by using computer analysis, the possibility of input errors, data falsification, etc. can be reduced, and as a result, an improvement in the accuracy of data analysis can be expected.

[0059] Moreover, in the tire center line calculation method according to this embodiment, after calculating the wheel center line and the brake disk surface using two types of jigs, the tire center line is calculated based on the calculated brake disk surface and the wheel center line. For this reason, in the conventional method of drawing a tire trace line and calculating the tire center line, since the drawn tire trace line is affected by the camber angle, an accurate tire center line could not be calculated. On the other hand, in the tire center line calculation method according to this embodiment, since the brake disk surface is calculated, a brake disk surface inclined by the camber angle of the tire is calculated. Therefore, the tire center line can be calculated without being affected by the camber angle of the tire, and an accurate tire center line can be calculated more accurately than the prior art.

[0060] Moreover, in the tire center line calculation method according to this embodiment, the tire center line can be calculated without being affected by the air pressure of the tire. Therefore, it is convenient in that the measurement can be performed regardless of the state of the tire to be measured, and an accurate tire center line can be calculated.

[0061] In addition, by using the tire center line calculation method according to the present embodiment, the simultaneous calculation of the tire center line, the tread, and the wheelbase can be easily performed. Therefore, the working efficiency is good and no special skills are required for the operator.

[0062] In addition, the jig used in the tire center line calculation method according to the present embodiment can be inserted as long as there is a spoke portion with a certain width. For this reason, there are many vehicle types that can be measured, and it has versatility.

[0063] In addition, in the tire center line calculation method according to the present embodiment, the jig is fixed to the disk brake parallel to the tire center plane, and the brake disk surface is calculated by measurement. However, the measurement target is not limited to the brake disk surface, and a jig applied to the drum portion of the drum brake may be attached and used for tire center line measurement. Further, as another embodiment, regarding the method of fixing the above-described jig to the brake disk surface, if an attachment method using a screw instead of a coupling method using a magnet is adopted, it is also possible to attach the jig to the bolt nut portion of the wheel and perform tire center line calculation.

[0064] In addition, the vehicle measurement method using the three-dimensional measurement technology according to the present embodiment is not limited to only the calculation of the tire center line, and can also be used for measuring the overall width of the vehicle. Specifically, after attaching the spindle jig and the brake disk jig to the wheel as described above, a plurality of the target seals are further attached to the left and right side surfaces of the vehicle. Then, after photographing with a high-resolution camera, the distance between the center points of the front tread and the rear tread is calculated as the wheelbase, and the extension line of the wheelbase in the front and rear directions of the vehicle is set as the vehicle center line. Then, a perpendicular line perpendicular to the surface plate is drawn through the target seal position points on the left and right side surfaces, and the intersection point of such a perpendicular line and the surface plate is calculated. Finally, the distances between the intersection point on the left side and the intersection point on the right side and the vehicle center line are calculated, and the sum of these two distances is the overall width of the vehicle.

[0065] In addition, the vehicle measurement method using the three-dimensional measurement technology according to the present embodiment may be used for measuring the overall length of a vehicle. Specifically, a plurality of the target seals are attached near the front part and the rear part of one vehicle. After that, after measuring the position information of each target seal, a point that is farthest from the line indicating the front tread and a point that is farthest from the line indicating the rear tread are selected, and perpendicular lines to the surface plate are drawn through each point. Then, the intersection points of the lines perpendicular to the surface plate and the surface plate are taken, and the two obtained points are represented in the two-dimensional space on the surface plate. Next, a perpendicular line to the vehicle center line is drawn through the two obtained points, and the intersection points with the vehicle center line are taken as successive points. Then, the distance between such successive points becomes the overall length of the vehicle.

[0066] In addition, the vehicle measurement method using the three-dimensional measurement technology according to the present embodiment may be used for measuring the overall height of a vehicle. Specifically, a plurality of target seals are attached around the top of the vehicle, and the positions of the target seals are measured in the same manner as before. Then, perpendicular lines to the surface plate are drawn through the points where each target seal is located. Then, the length of the perpendicular line between this point and the standard surface becomes the height of each point, and the one with the longest such length is calculated as the overall height of the vehicle.

[0067] The above-described embodiments are merely examples, and the present invention is not limited to such embodiments. Therefore, even outside the above-described embodiments, various changes can be made according to the design and the like as long as the technical idea according to the present invention is not deviated from. In addition, the effects described in the present disclosure are merely examples, and there may be other effects.

Explanation of Reference Numerals

[0068] 1 Target seal 2 Identification seal 3 Upper cylindrical part 3a Upper surface part 3b Outer peripheral surface part 4 Lower cylindrical part 4a Lower surface part 4b Inner space part of the lower cylindrical part 5 Spindle jig 6 Hollow structure 7 Magnet 10 Body part 10a Upper surface part of the body part 10b Side surface part of the body part 10c Bottom surface of the body part 10d Hollow part of the body 11 Cylindrical rod part 11a Lower end part of the cylindrical rod part 12 Brake disc jig 20 Surface plate reference jig 21 Tire part 22 Wheel part 23 Spoke part 24 Wheel center 30 Tire center plane 31 Brake disc 31a Brake disc surface 32 Surface plate 33 Wheel center line 34 Center point of the tire center plane 35 Temporary point 36 Tire center point 50 Tire

Claims

1. A jig used for calculating the tire center line that can be fixed to the wheel center of a vehicle tire, having an upper cylindrical portion and a lower cylindrical portion provided below the upper cylindrical portion, a target display portion for measuring position information is provided on the upper surface portion forming the upper surface of the upper cylindrical portion and on the outer peripheral surface portion of the upper cylindrical portion, an identification display portion for identifying the spatial position of the jig is provided on the upper surface portion, a magnet for the purpose of fixing to the wheel center is disposed at the edge of the lower cylindrical portion A jig used for calculating the tire center line, characterized in that.

2. A jig used for calculating the tire center line that is inserted between the spoke portions of the wheel portion of a vehicle tire, having a main body portion that is the head, and a support rod portion having one end connected to the bottom surface portion of the main body portion, a target display portion for measuring position information is provided on the side surface portion of the main body portion, an identification display portion for identifying the jigs inserted between the spoke portions is provided on the upper surface portion of the main body portion, a magnet for the purpose of fixing to the brake disc provided inside the wheel portion is disposed on the end surface portion of the other end side of the support rod portion A jig used for calculating the tire center line, characterized in that.

3. A method for calculating the tire center line using these jigs, where the jig according to Claim 1 is the first jig and the jig according to Claim 2 is the second jig, a step of fixing the first jig to the wheel center of the vehicle, a step of inserting three or more of the second jigs between the spoke portions of the wheel portion and fixing the second jigs to the brake disc, a step of calculating the position information of the two types of jigs, the first jig and the second jig, and calculating three-dimensional coordinates by a surveying method that represents the position information such as photogrammetry as a three-dimensional diagram, a step of calculating a center line passing through the center of the first jig as the wheel center line from the position information of the first jig, a step of calculating the brake disc surface of the brake disc from the position information of the second jig, a step of offsetting the calculated brake disc surface so as to pass through the tire center portion to calculate the tire center plane, A method for calculating the tire center line, characterized by including.

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