JP4150108B2 - Tire electrical resistance measuring instrument - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tire electrical resistance measuring instrument.
[0002]
[Prior art]
In recent years, in order to develop a fuel-efficient tire, a tire containing silica is increasingly employed. For this reason, the electrical resistance between the tread and the bead of the tire tends to increase. When the electrical resistance between the tread and the bead is high, for example, when it is 100 MΩ or more, the tire is charged and sometimes discharged, which may cause a problem of generation of radio noise. For this reason, the report of the exact electrical resistance value of the tire has come to be requested from automobile manufacturers and the like.
[0003]
Conventionally, in order to measure the electrical resistance value of a tire, for example, as shown in FIGS. 7A and 7B, a support part c provided with a tooth part on the inner side of the tip part and swinging to the support part c An abutment tool f having an alligator-type terminal a having a swinging member d which is pivotally attached and provided with a tooth portion inside the tip portion, and a tapered tip portion e as shown in FIG. In some cases, a resistance measuring instrument including a contact tool g including a terminal b having a resistance value measurement display box (not shown) is used. When using the resistance measuring instrument, the bead portion of the tire is pinched at the terminal a of the contact tool f and the tapered tip e of the terminal b of the contact tool g is pressed against the tread portion by the power of a human hand. It was.
[0004]
[Problems to be solved by the invention]
Incidentally, contact resistance is generated between the tire and the terminal. The contact resistance is divided into concentrated resistance and boundary resistance. The boundary resistance is generated when a film of foreign matter is formed on the contact surface, and this can be prevented by cleaning the tire and the terminal. In addition, the concentrated resistance is generated by narrowing the passage because the current passes through a small contact surface. In order to reduce the concentrated resistance, it is necessary to increase the contact area and sufficiently increase the contact force.
[0005]
However, in the conventional measuring instrument as described above, the contact area between the terminal a and the bead portion is remarkably small, and the contact area between the terminal b and the tread portion is remarkably small, so that the concentrated resistance is increased. Further, since the tapered tip end e of the terminal b is pressed against the measurement site (tread portion) of the tire by the force of a human hand, the contact area and the contact force vary. As a result, the measured value of the electrical resistance of the tire varies greatly, and the true resistance becomes unknown or the measured value becomes inaccurate.
[0006]
Therefore, the present invention solves the above-described problems, can increase the contact area between the tire and the terminal, can make the contact area constant, and can accurately measure the electrical resistance value of the tire. An object of the present invention is to provide a possible tire electrical resistance measuring instrument.
[0007]
[Means for Solving the Problems]
In order to achieve the above-described object, a tire electrical resistance measuring device according to the present invention includes a first contact tool including a bead terminal having a contact surface pressed against a bead portion of the tire, and a tire tread. A second abutting tool having a tread terminal formed with an abutting surface pressed against the portion, and a resistance measurement electrically connected to the first abutting tool and the second abutting tool via an electric cord A display means for displaying a resistance value measured by the resistance measuring circuit, wherein the bead terminal of the first contact tool is a conductive metal piece, and the contact surface of the bead terminal is When the angle formed between the vertical portion and the inclined portion is θ, the angle is set to 92 ° ≦ θ ≦ 98 °, and the above-mentioned first flat surface abutting surface of the tread terminal with the second contact member conductive metal piece tread terminals And, and, to the respective terminals, welded the handle portion for gripping, furthermore, it is obtained by setting the curvature radius of the corner portion of the first abutment surface to 0～7.0Mm.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments.
[0009]
FIG. 5 shows a tire electrical resistance measuring device according to the present invention, and FIG. 6 shows a state in which the electrical resistance value between the bead portion 1 and the tread portion 2 of the tire T is measured by the tire electrical resistance measuring device A. Indicates. Thus, the tire electrical resistance measuring device A is provided with a contact tool 3 (first contact tool 3a) for contacting the bead part 1 of the tire T and a tread part 2 of the tire T. Measured by the contact measurement tool 6 (second contact tool 3b), the resistance measurement circuit 6 electrically connected to the contact tools 3 and 3 via the electric cords 5 and 5, and the resistance measurement circuit 6. Display means 7 for displaying the resistance value.
[0010]
The resistance measuring circuit 6 and the display means 7 are housed in a portable box 8. That is, a circuit for measuring electrical resistance is built in the box 8, and a meter 9 for displaying a resistance value and switches not shown are attached to the box 8.
[0011]
Thus, as shown in FIGS. 1 and 2, the first abutment tool 3a includes a bead terminal 4a (terminal 4) formed with an abutment surface 10 pressed against the outer surface of the bead portion 1 of the tire T. A grip handle 11 welded to the bead terminal 4a. The contact surface 10 of the bead terminal 4a is L-shaped in side view. That is, the cross-sectional shape of the contact surface 10 of the terminal 4 is set to be substantially the same as the cross-sectional shape of the outer surface of the tire T.
[0012]
Specifically, the bead terminal 4a is made of an L-shaped conductor piece (conductor metal piece) in side view, and the contact surface 10 is made of a vertical portion 10a, a corner portion 10b, and an inclined portion 10c. . Furthermore, when the angle formed by the vertical portion 10a and the inclined portion 10c is θ, 92 ° ≦ θ ≦ 98 ° is set.
[0013]
The reason for setting in this way is that when the angle θ is less than 92 ° or exceeds 98 °, the corner portion 1a on the outer side of the bead portion 1 of the tire T and its vicinity and the bead terminal 4a. This is because the contact area with the abutment surface 10 is remarkably reduced, the contact resistance (concentration resistance) is increased, and the resistance value measurement accuracy of the tire is deteriorated. Further, it is preferably set to 94 ° ≦ θ ≦ 96 °. By doing so, the contact area becomes extremely large and the contact resistance is remarkably reduced, so that the resistance value measurement accuracy is increased.
[0014]
Further, the radius of curvature R of the corner portion 10b is set to 0 to 7.0 mm. This is because, when the radius of curvature R of the corner portion 10b exceeds 7.0 mm, the contact area between the corner portion 1a and the vicinity thereof and the contact surface 10 becomes remarkably small, and the contact resistance (concentration resistance) increases. This is because the tire resistance measurement accuracy is deteriorated. When the radius of curvature R of the corner portion 10b is 0 mm, the corner portion 10b is formed as a corner portion without roundness. Particularly preferably, the radius of curvature R is set to 6.5 mm or less. By doing so, the contact area between the bead portion 1 of the tire T and the contact surface 10 of the bead terminal 4a becomes extremely large, and the contact resistance (concentrated resistance) is remarkably reduced, so that the resistance measurement accuracy is increased. .
[0015]
The handle 11 is made of a conductor, and the tip is welded to the outer surface of the corner of the bead terminal 4a. Of the handle portion 11, a portion protruding from the bead terminal 4 a is covered with an insulating jacket 13. Specifically, the handle portion 11 is fitted with a tip portion into a hole portion 14 provided on a corner outer surface of the bead terminal 4a, and further welded (soldered) at an opening edge portion of the hole portion 14. Is done. The electric cord 5 is connected to the base end portion of the handle portion 11.
[0016]
Next, as shown in FIGS. 3 and 4, the second abutment tool 3 b includes a tread terminal 4 b (terminal 4) having a contact surface 10 that is pressed against the outer surface of the tread portion 2 of the tire T. And a grip handle 11 welded to the tread terminal 4b. Further, the contact surface 10 of the tread terminal 4b is a flat surface.
[0017]
Specifically, the tread terminal 4b is formed of a substantially square conductor piece (conductor metal piece) when viewed from the front, and the contact surface 10 is a flat square surface. Then, the handle portion 11 is fixed at a right angle to the back side of the tread terminal 4b. That is, the hole 15 is provided on the back surface of the tread terminal 4b, the tip of the handle 11 is fitted into the hole 15, and further welded (soldered) at the opening edge of the hole 15. Further, a portion of the handle portion 11 that protrudes from the tread terminal 4 b is covered with an insulating jacket 13.
[0018]
In addition, as a material of the terminal 4a for beads and the terminal 4b for treads, it is preferable to use what chrome-plated the copper piece, for example. Of course, other materials having good conductivity can be used freely, but it is desirable to use a material having a low resistivity and a low hardness.
[0019]
Next, in order to use the tire electrical resistance measuring instrument A, the bead terminal 4a of the first abutment tool 3a is connected to the corner 1a on the outer side of the bead portion 1 of the tire T as shown in FIG. The tread terminal 4b of the second abutment tool 3b may be brought into contact with the intermediate portion of the tread portion 2 of the tire T with the other hand.
[0020]
Thus, according to the tire electrical resistance measuring instrument A, the contact area between the bead terminal 4a and the bead portion 1 of the tire T and the contact area between the tread terminal 4b and the tread portion 2 of the tire T are increased. Since the contact pressure can be made sufficiently large and uniform, the contact resistance is remarkably small and uniform. Therefore, the measurement accuracy of the electrical resistance value of the tire T is remarkably increased. Moreover, the structure of the 1st contact tool 3a for beads and the 2nd contact tool 3b for treads is simple, and can be manufactured easily. Moreover, it is easy to handle.
[0021]
【Example】
A measuring device similar to the tire electrical resistance measuring device A shown in FIGS. 1 to 6 was actually produced and used as an example of the present invention. As for the size of the tread terminal, the contact surface was 25 mm square and the thickness was 5 mm. As for the size of the terminal for the bead portion, the length of the upper and lower sides of the contact surface was 25 mm, the length of the left and right sides of the L-shape in side view was 25 mm, and the thickness was 5 mm. In addition, as a conventional example, an electrical resistance measuring device having terminals shown in FIGS. 7A and 7B and FIG. 8 was prepared.
[0022]
The measurement test of the electrical resistance between the bead and the tread of the tire was performed according to the above example and the conventional example. The tire used was 205 / 65R15 94S. As a measuring method, the position was changed by 90 ° in the circumferential direction of the tire, the terminals were brought into contact with the tread and the bead, respectively, and the measurement was performed 40 times in total (40 locations). The measurement results are shown in the graph of FIG.
[0023]
The average is 37.7 × 10 ^-2 MΩ of resistance value of the conventional example from the results of the measurement test, the standard deviation is 4.6 × 10 ^-2 MΩ, the difference between the maximum value and the minimum value of the measured values (hereinafter, this The measured value range was 26.9 × 10 ⁻² MΩ. Moreover, the average of the electrical resistance value of the Example was 26.0 × 10 ⁻² MΩ, the standard deviation was 0.9 × 10 ⁻² MΩ, and the measurement value range was 5.0 × 10 ⁻² MΩ. As is apparent from this result and FIG. 9, the variation in the measurement result (electric resistance value) in the example is significantly smaller than that in the conventional example. In addition, the example has a smaller electrical resistance value as a whole than the conventional example. (In other words, the average electrical resistance value is small.)
[0024]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
[0025]
According to the tire electrical resistance measuring instrument of the present invention, the contact area between the terminal 4 of the abutment tool 3 and the outer surface of the tire T can be made large and constant, and the range of measured values is remarkably reduced. That is, since the contact pressure does not vary every time measurement is performed, the measurement value (electric resistance value) does not vary. Therefore, the measurement accuracy of the electrical resistance value of the tire T is remarkably increased.
Moreover, the contact area of the terminal 4 with respect to the bead part 1 of the tire T can be increased effectively, and the contact pressure can be made sufficiently large and uniform.
In addition, the structure of the first contact tool 3a for beads and the second contact tool 3b for tread is simplified and can be manufactured easily. Moreover, the handling is simple, and the electrical resistance of the tire T can be measured easily and accurately by one worker.
[0026]
Further, the terminal 4 of the abutment member 3 to the tire T by the hand of man, it is possible to easily contact and cut in preventing variations in the contact area with the contact pressure.
[Brief description of the drawings]
FIG. 1 is a side view showing an example of a tire electrical resistance measuring contact tool according to the present invention.
FIG. 2 is a perspective view of a main part.
FIG. 3 is a side view showing another example of a tire electrical resistance measuring contact tool according to the present invention.
FIG. 4 is a perspective view of a main part.
FIG. 5 is a simplified diagram showing an embodiment of a tire electrical resistance measuring device according to the present invention.
FIG. 6 is an explanatory diagram of a measurement method.
FIG. 7 is an explanatory diagram of a conventional example.
FIG. 8 is an explanatory diagram of a conventional example.
FIG. 9 is a graph.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Bead part 2 Tread part 3a 1st contact tool 3b 2nd contact tool 4 Terminal 4a Terminal for bead 4b Terminal for tread 5 Electrical cord 6 Resistance measurement circuit 7 Display means
10 Contact surface
10a Vertical section
10b Corner
10c Inclined part
11 Handle R Radius of curvature T Tire θ Angle

Claims (1)

A first contact tool 3a having a bead terminal 4a formed with a contact surface 10 pressed against the bead portion 1 of the tire T, and a tread formed with a contact surface 10 pressed against the tread portion 2 of the tire T. A second abutting tool 3b having a terminal 4b, a resistance measuring circuit 6 electrically connected to the first abutting tool 3a and the second abutting tool 3b via electric cords 5 and 5, Display means 7 for displaying the resistance value measured by the resistance measurement circuit 6 ,
The bead terminal 4a of the first abutment tool 3a is a conductive metal piece, and the abutment surface 10 of the bead terminal 4a is L-shaped in a side view including a vertical portion 10a, a corner portion 10b, and an inclined portion 10c. , an angle between該鉛straight portion 10a and the inclined portion 10c when the theta, and set to 92 ° ≦ θ ≦ 98 °,
In addition, the tread terminal 4b of the second contact tool 3b is a conductive metal piece, and the contact surface 10 of the tread terminal 4b is a flat surface .
And, a handle 11 for gripping is welded to each of the terminals 4a and 4b ,
Furthermore, the first tire electric resistance measuring instrument curvature radius R of the corner portion 10 b of the contact surface 10, characterized in that set to 0 to 7.0 mm.

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