JP7160506B2 - Vehicle parts contamination evaluation method - Google Patents

Description

The present invention relates to a method for evaluating the degree of dirt adhering to vehicle parts such as wheels.

In recent years, there has been an increase in the number of vehicle users pointing out dirt on wheels due to brake dust. In order to respond to this point, there is a demand for the development of brakes that take into consideration not only braking performance such as effectiveness, suppressing squeal, and ensuring wear life, but also considering wheel dirt. In order to develop such brakes, it is necessary to objectively and quantitatively evaluate wheel contamination.

However, no technology has been established for accurately evaluating wheel contamination. In general, wheel dirt is evaluated by human eyes. In visual evaluation, the results are influenced by human subjectivity, and there are variations in evaluation due to differences in people. Furthermore, it is not possible to quantitatively assess wheel contamination. As a result, it is not possible to compare and evaluate brakes from different manufacturers on the basis of a single standard.

On the other hand, Patent Literature 1 discloses a technique for evaluating contamination of components of automobiles. This technique relates to a cylindrical object inspection method for automatically inspecting dirt, scratches, etc., on a piston skirt of an engine. Specifically, it has the following steps.
(1) Compute the three elements of the reference color based on the color system.
(2) Search for an image to be processed from among the images of the cylindrical object.
(3) Compare the three elements of the reference color with the three elements of the color of the image to be processed.
(4) Based on the result of this comparison, the evaluation of contamination, etc., on the outer peripheral portion of the cylindrical object is calculated.

JP-A-6-201598

However, wheel contamination is difficult to accurately evaluate based on the color system. The reason for this is that the measurement accuracy of dirt attached to a portion where curved surfaces with small curvatures are continuous is lowered even if the spectrophotometer is used to directly measure the dirt. In particular, the surface of the wheel is generally composed of a plurality of types of curved surfaces with different curvatures and has a complicated shape, and the curvature of each curved surface is often small, so the decrease in measurement accuracy tends to be more pronounced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and one of its objects is to provide a vehicle part dirt evaluation method capable of quantitatively evaluating the degree of dirt adhering to a vehicle part such as a wheel. That's what it is.

(1) A vehicle component dirt evaluation method according to the first aspect of the present invention includes:
A process of attaching a collection member to which dirt is attached to the surface of a vehicle part;
a step of attaching dirt to the surface of the collecting member attached to the vehicle part;
a step of measuring the optical characteristic value of the surface of the collecting member to which dirt adheres;
The collecting member is
a first layer adhered to the vehicle component;
A second layer that is detachably laminated to the first layer,
The process of measuring the optical property value includes:
a step of peeling off the second layer from the collecting member to which dirt has adhered;
fixing the second layer on a planar surface;
and measuring optical property values of the surface of the second layer fixed on the plane.

In the method for evaluating dirt on vehicle parts described above, dirt is attached to the surface of the collection member having a laminated structure, the second layer, which is a part of the collection member, is peeled off from the first layer, fixed on a plane, and then the second layer is removed. Measure the optical properties of the surface of the bilayer. Therefore, even when the collecting member is adhered to a curved surface, the optical characteristic value of the surface of the collecting member can be accurately measured without relying on human senses. In particular, dirt can be objectively and quantitatively evaluated even for a vehicle part having a curved surface with a small curvature or a vehicle part having a plurality of curved surfaces with different curvatures.

It is an explanatory view of the dirt evaluation method of the wheel according to the embodiment. FIG. 4 is a partial schematic diagram showing a wheel to which a collecting member is attached in the wheel dirt evaluation method according to the embodiment. It is a graph which shows the result of the dirt evaluation method of the wheel which concerns on embodiment.

[Embodiment 1]
An embodiment of the present invention will be described with reference to the drawings. Here, an embodiment will be described mainly with reference to FIG. 1, taking as an example a vehicle part dirt evaluation method in which the vehicle part is the wheel 10, the dirt is the brake dust, and the optical characteristic to be measured is the lightness.

[Overview]
This vehicle component contamination evaluation method includes an initial process, a contamination adhesion process, and a measurement process. In the initial process, the collecting member 20 to which dirt adheres is attached to a predetermined position on the surface of the vehicle component. In the dirt adhesion process, dirt is made to adhere to the surface of the collection member 20 attached to the vehicle component. In the measurement process, the optical characteristic value of the surface of the collecting member 20 to which dirt adheres is measured. One of the features of the vehicle component contamination evaluation method according to the embodiment is that the collecting member 20 has a predetermined laminated structure, and the collecting member 20 is partially peeled off and fixed on the plane 30 during the measurement process. Then, the optical characteristic value of the part of the layer is measured. Each process will be described in detail below.

[Initial process]
The initial process includes a process of preparing the collecting member 20 and a process of attaching the collecting member 20 .

(Preparation process of collecting member)
In the preparation process of the collecting member 20, the collecting member 20 having a predetermined laminated structure is prepared. This collection member 20 comprises a first layer 21 adhered to the wheel 10 and a second layer 22 peelably laminated on the first layer 21 . More specifically, commercially available double-sided adhesive tape can be used as the collecting member 20 . Commercially available double-sided adhesive tapes can be obtained easily and inexpensively. In general, double-sided adhesive tapes have adhesive layers on both sides of a substrate, and a release layer on at least one of the adhesive layers. In such a double-sided adhesive tape, for example, the first layer 21 is the adhesive layer on one side of the substrate, that is, the side facing the wheel 10, and the release layer is laminated on the adhesive layer on the other side of the substrate. is used as the second layer 22 . It is preferable that the first layer 21 has adhesive strength to the extent that it does not come off easily when adhered to the wheel 10 . The second layer 22 is a layer to which dirt is directly adhered, and maintains a laminated state with the first layer 21. However, it is required that the second layer 22 can be easily peeled off from the first layer 21 as necessary. For example, as the second layer 22, a release layer obtained by coating a paper such as kraft paper or a resin film such as PET with a silicon-based polymer can be used. Brake dust can adhere to such a release layer appropriately, and it is easy to appropriately determine the adhesion state of brake dust associated with different brakes in the subsequent measurement process. If the adhesive layer is used as the second layer 22, brake dust adheres excessively, and it may be difficult to determine the adherence of brake dust due to different brakes during the measurement process. The above-mentioned double-sided adhesive tape has a laminated structure composed of four or five layers, and the substrate and the adhesive layer on the other side of the substrate are interposed between the first layer 21 and the second layer 22. However, no other layer may be interposed between the first layer 21 and the second layer 22 . In FIG. 1, only the first layer 21 and the second layer 22 are shown for simplification.

The size of the collecting member 20 is set to be larger than the measurement area (measurement diameter) of the measuring instrument used later in the measurement process. For example, if the measurement diameter of the spectrophotometer 40 is less than φ10 mm, the size of the collecting member 20 should be selected so as to secure an area larger than that. On the other hand, if the size of the collecting member 20 is too large, it will be difficult for dirt to adhere uniformly. For example, it is preferable to use a collection member 20 of approximately 10 to 20 mm×50 to 150 mm.

It is preferable that the brightness of the surface of the second layer 22 to which dirt adheres is substantially uniform over the entire surface of the second layer 22 and is high. This is because, if the surface to which the dirt adheres has a uniform and high brightness, the change in brightness can be clearly grasped when the dirt adheres. White has the highest brightness and is suitable for the second layer 22 . For example, it preferably has a brightness value of 90 or more according to the L ^* a ^* b ^* color system (JIS Z 8781-4). However, even the second layer 22 with a brightness value of less than 90 can be used by multiplying the brightness value by a correction value. When evaluating the degree of adhesion of dirt with different brakes on the wheel 10, it is preferable to use the same lightness for the second layer 22 used in each measurement. However, even when the second layer 22 having different lightness is used at the time of measurement, by multiplying the correction value according to the difference in lightness, it is possible to obtain an evaluation result that can be appropriately compared.

(Affixing process of collecting member)
In the attaching process of the collecting member 20, as shown in FIG. In FIG. 2, the back side of the paper indicates the outer side in the vehicle width direction, and the front side of the paper indicates the inner side in the vehicle width direction. This attachment is performed with the first layer 21 of the collection member 20 facing the wheel 10 . Wheel 10 generally comprises a disc portion 11 mounted on an axle and a rim portion 12 on which a tire is mounted. The disk portion 11 includes a central hub attachment portion and a plurality of spoke portions radially extending from the hub attachment portion to the outer peripheral side. The rim portion 12 is an annular member integrated with the outer peripheral side of the disc portion 11 . In such a wheel 10, the locations where the collecting member 20 is attached include the following positions a to f.
a: Outer surface of spoke (surface facing outside in vehicle width direction)
b: side of spoke (surface facing adjacent spoke)
c: the outer surface of the rim portion 12 (the surface facing the outside in the vehicle width direction)
d: A portion of the inner peripheral surface of the rim portion 12 that is inner than the disk portion 11 in the vehicle width direction and closer to the disk portion 11 e: A portion of the inner peripheral surface of the rim portion 12 that is closer to the disk portion 11 than the disk portion 11 in the vehicle width direction Inside and on the side opposite to the disk part 11 f: Between the spokes and between the above position c and position d

It is preferable to select a location where the collection member 20 is adhered to a location where there is little variation in adhesion of dirt. Specifically, the position d, that is, the vicinity of the disk portion 11 on the inner peripheral surface of the rim portion 12 of the wheel 10 is preferable. This attachment location may include a curved surface. This curved surface may be a curved surface with a small radius of curvature. For example, even a curved surface with a curvature radius of 150 mm or less, further 100 mm or less, and particularly 50 mm or less can be appropriately evaluated for contamination. Furthermore, this pasting location may include a plurality of curved surfaces with different radii of curvature.

When the collecting member 20 is attached to the curved surface of the wheel 10, the collecting member 20 may be cut appropriately if necessary. By making a cut, it is possible to suppress the trapping member 20 attached to the curved surface from being folded or wrinkled.

[Dirt adhesion process]
In the dirt adhesion process, the wheel 10 to which the collecting member 20 is attached is exposed to an environment under certain conditions in which dirt is generated, so that dirt adheres to the surface of the collecting member 20 . At that time, the surface of the second layer 22 is exposed without being covered with other members, and dirt is directly adhered thereon. As a specific example, first, the wheel 10 to which the collection member 20 is attached is mounted on the vehicle. Next, the vehicle is driven on the chassis dynamometer and braked under predetermined conditions. Brake dust adheres to the collecting member 20 with this braking. Specific examples of the predetermined braking conditions include Pattern A and Pattern B below.
(A) Vehicle speed: 50 km/h→0 km/h, deceleration: 1.5 m/s ² , number of times of braking: 770 times in total, braking interval: 60 seconds (B) Vehicle speed: 10 to 100 km/h, deceleration: 0 .6 to 6.0 m/s ² , number of braking: 2000 times in total, braking interval: 60 seconds

Either one of pattern A and pattern B may be performed, or both may be performed. When performing both, the order of each pattern does not matter.

[Measurement process]
The measuring process includes a peeling process, a fixing process to the plane 30, and an optical characteristic value (brightness) measuring process.

(Peeling process)
In the peeling process, as shown in FIG. 1, the second layer 22 is peeled off from the collecting member 20 that has undergone the dirt adhesion process. At this time, the adhered brake dust is carried out so as not to drop off from the second layer 22 . For example, by not allowing the second layer 22 to bend excessively, brake dust can be prevented from coming off.

(fixing process to plane)
In the fixing process to the flat surface 30 , the peeled second layer 22 is fixed on the flat surface 30 . This fixation is carried out with the soiled surface of the front and back surfaces of the second layer 22 facing upward, and the surface without soiling facing the flat surface 30 . For this flat surface 30, a suitable top plate such as a desk or a table, or a plate material or a sheet material placed on the top plate can be used. The means for fixing the second layer 22 to the plane 30 is not particularly limited as long as the second layer 22 does not inadvertently shift from the plane 30 . As a specific example, a double-sided adhesive tape may be interposed between the second layer 22 and the flat surface 30, or the edges and corners of the second layer 22 may be pressed with an adhesive tape.

(Brightness measurement process)
In the lightness measurement process, the optical characteristic value of the dirty surface of the second layer 22 fixed to the flat surface 30 is measured. This measurement is not particularly limited as long as at least brightness can be measured. A commercially available spectrophotometer 40 can be suitably used for the measurement of brightness. Specific examples include CM-700d and CM-600d manufactured by Konica Minolta. If at least the visible light region can be used as the measurement wavelength, contamination can be properly evaluated. The visible light range is, for example, about 360 to 830 nm, but the wavelength range of about 400 to 700 nm is sufficient for practical evaluation of stains.

In the lightness measurement process, it is preferable to use a wrap film 50 such as Saran Wrap (registered trademark). For example, the surface of the second layer 22 that has undergone the fixing process to the flat surface 30 is covered with a wrap film 50, and the lightness is measured from above the wrap film 50. FIG. The wrap film 50 preferably covers the surface of the second layer 22 so that it does not wrinkle. By covering the surface of the second layer 22 with the wrap film 50 , it is possible to more reliably prevent brake dust from coming off the second layer 22 and from adhering to the spectrophotometer 40 . As an example of the wrap film 50, one having a thickness of about 10 μm and a haze of about 0.3% can be suitably used. It should be noted that the wrapping film 50 may not be used in the peeling process or the fixing process to the flat surface 30 .

A spectrophotometer 40 quantifies optical characteristics such as lightness, hue, and saturation. For quantification of this optical characteristic, L ^* a ^* b ^* color system (JIS Z 8781-4), L ^* u ^* v ^* color system (JIS Z 8781-5), XYZ color system (JIS Z 8701) can be used. Among them, the L ^* a ^* b ^* color system is preferable because it is close to the sensitivity of the human eye. The L ^* a ^* b ^* color system is a color system that expresses colors by values on three-dimensional coordinates of the L ^* axis, the a ^* axis, and the b ^* axis. The L ^* axis is a lightness axis that indicates brightness, and when it is close to 0, it indicates black, and when it is close to 100, it indicates white. The a ^* axis represents green to red. The b ^* axis represents blue to yellow. The larger the numerical value on both the a ^{* axis and the b* axis} , the higher the saturation. The stain to be evaluated in this example is brake dust, which is generally black in color. Therefore, among the optical characteristics, if the brightness can be measured, the stain on the wheel can be evaluated. That is, when the value on the L ^* axis is small, it can be evaluated that the adhesion of brake dust is large, and when the value on the L ^* axis is large, the adhesion of brake dust is small.

The lightness measurement may be performed at only one point of the second layer 22 fixed on the plane 30, or the measured values at a plurality of points may be averaged. In any case, when the evaluation method of this example is performed with different brakes, it is desirable to measure the brightness at the same position on the second layer 22 .

[Brake change]
By repeating the series of evaluation methods including the initial process, the dirt adhesion process, and the measurement process by changing the brake, it is possible to compare and evaluate the state of dirt adhesion to the wheel 10 for each brake. For example, at least one of a disc and a pad is included in the change target of the brake.

[Evaluation of dirt]
To evaluate dirt, a reference value of lightness is selected, and the amount of adhered brake dust can be appropriately evaluated from the difference in the measured value with respect to the reference. Selection of the reference is performed, for example, as follows. First, using each of a plurality of existing brakes manufactured by different manufacturers, the above dirt evaluation method is carried out. FIG. 3 is a graph showing the evaluation results of brake dust adherence to the wheel 10 using four types of brakes from Company A, four types from Company B, and three types of brakes from Company C. As shown in FIG. The vertical axis of the graph indicates the brightness value of the surface of the second layer 22 of the collecting member 20, and the horizontal axis indicates the brake model number of each company. As shown in this graph, the value of brightness differs for each brake, but there are brakes that exhibit approximately the same value of brightness between manufacturers. Therefore, brakes having substantially the same lightness can be selected as a reference material for each manufacturer based on the dirt evaluation results. For the reference material of each manufacturer, for example, the maximum difference in brightness value is 5 or less, particularly 3 or less. In this example, the maximum difference is 3 or less. The value indicating the minimum brightness value among the brightness values measured using the reference material, the average value of the brightness values of the reference materials of each manufacturer, and the brightness values of the reference materials of each manufacturer are approximated by the least-squares method. The converted value may be used as the reference brightness value. Here, brake A3, brake B1, and brake C3 are used as reference materials of each company. In the graph, the minimum lightness value of the reference material of each manufacturer (here, the value of C3) is indicated by a horizontal line as the reference lightness value. The reference brightness value selected in this manner can be used as a common absolute reference even for brakes made by different manufacturers. Therefore, even for brakes that have not been evaluated for contamination, such as brakes newly developed by different manufacturers, the above contamination evaluation method is implemented for each of the brakes that have not been evaluated, and the evaluation results are used to evaluate the reference material. It can be compared with the result (reference brightness value). By this comparison, it is possible to quantitatively and accurately determine whether the amount of brake dust adhering to the wheel 10 is greater or less than that of the reference material. If there is no common brightness value in the brakes of each company, for example, even if the maximum difference in brightness value is more than 5, the brake with the smallest difference in brightness value among the brakes of each company is used as the reference material. should be selected as The minimum value, average value, or approximate value of the brightness values of these reference materials may be used as the reference brightness value.

[Effect]
(1) The dirt evaluation method of the wheel 10 according to the above-described embodiment involves attaching dirt to the surface of the collection member 20 having a laminated structure, , and fixed to the flat surface 30 before measuring the brightness of the surface of the second layer 22 . Therefore, even when the collecting member 20 is adhered to a curved surface, the brightness of the surface of the collecting member 20 can be accurately measured without relying on human senses. In particular, the contamination can be objectively and quantitatively evaluated even for the wheel 10 having a curved surface with a small curvature or the wheel 10 having a plurality of curved surfaces with different curvatures.

(2) By using the release layer of the double-sided adhesive tape as the second layer 22, brake dust does not excessively adhere to the second layer 22, and dirt on the wheel 10 can be evaluated appropriately. In addition, this release layer can be easily peeled off from the adhesive layer, which is the first layer 21, and can prevent brake dust from coming off during the peeling.

(3) Adhering the collecting member 20 to the inner peripheral surface of the rim portion 12 of the wheel 10 near the disk portion 11 enables proper evaluation of dirt. This is because, at this position, the variation in adhesion of dirt to the collecting member 20 is small.

(4) Even if brakes are manufactured by different manufacturers, by selecting brakes having a common brightness value for each manufacturer as a reference material in advance, the brightness value measured using that reference material is used as the reference brightness value. can do. Therefore, if the above dirt evaluation method is performed for each new brake that has not yet been evaluated, the evaluation result can be compared with the evaluation result (reference lightness value) of the reference material to determine whether the brake dust adheres to the wheel 10. is more or less than that of the reference material can be quantitatively and accurately determined.

(5) By using the wrap film 50 in the lightness measurement process, it is possible to prevent brake dust from falling off from the second layer 22 and from adhering to the spectrophotometer 40 .

[Modification]
The present invention is not limited to these exemplifications, but is indicated by the scope of the claims, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims. In the above embodiment, the release layer of the double-sided adhesive tape is used as the second layer 22, but the adhesive layer of the double-sided adhesive tape can be used as the second layer 22 depending on the type of dirt to be adhered. The type of dirt may be particulate solids such as brake dust, as well as colored liquids and mixtures of liquids and particulates. In the above embodiment, staining is evaluated based on the lightness measurement result, but staining may be evaluated using at least one of hue and saturation in addition to or instead of lightness. Parameters corresponding to the hue and saturation include, for example, at least one of the values of the a ^* axis and the b ^* axis of the L ^* a ^* b ^* color system. In addition, by making the material of the second layer 22 the same as or similar to the material of the wheel 10, the surface of the second layer 22 can accurately simulate the state of adhesion of dirt to actual vehicle parts. For example, if the wheel 10 is an aluminum alloy, the second layer 22 may be made of the same or similar aluminum alloy foil.

The method for evaluating contamination of vehicle parts according to the embodiment of the present invention is used, for example, in the development of brakes that generate less brake dust and in the development of wheels that are resistant to adhesion of brake dust. can be used for objective evaluation.

10 wheel 11 disc part 12 rim part 20 collection member 21 first layer 22 second layer 30 plane 40 spectrophotometer 50 wrap film

Claims (1)

A process of attaching a collection member to which dirt is attached to the surface of a vehicle part;
a step of attaching dirt to the surface of the collecting member attached to the vehicle part;
a step of measuring the optical characteristic value of the surface of the collecting member to which dirt adheres;
The collecting member is
a first layer adhered to the vehicle component;
A second layer that is detachably laminated to the first layer,
The surface of the second layer does not have stickiness,
The process of measuring the optical property value includes:
a step of peeling off the second layer from the collecting member to which dirt has adhered;
fixing the second layer on a planar surface;
and measuring an optical characteristic value of the surface of the second layer fixed on the plane.

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