JP4755044B2 - Vehicle charging potential evaluation method - Google Patents

Description

  The present invention relates to a vehicle charging potential evaluation method for evaluating a charged state due to static electricity generated by friction between a tire and a road surface, and more particularly to a vehicle charging potential evaluation method that can be evaluated without being influenced by weather or humidity.

  Carbon black is blended in rubber used for pneumatic tires in order to increase strength. In recent years, in order to increase the wear resistance of tire tread rubber and reduce rolling resistance of tires, silica is often added to tread rubber together with carbon black. For example, a pneumatic tire described in Patent Document 1 is known.

Japanese Patent Laid-Open No. 9-30206

  Since the electrical conductivity of silica is lower than that of carbon black, the volume resistivity of the tread rubber containing silica is higher than that of the conventional tread rubber. As a result, static electricity generated by friction between the running tire and the road surface is easily charged to the vehicle via the tire and the wheel.

  When a vehicle charged with static electricity passes over a metal installation (such as a manhole or grating grounded on the ground) installed on the road, the charged static electricity is discharged at once through the conductive part of the tire. The Electromagnetic waves are generated by this discharge, and become noise that hinders reception of radio and television installed in the vehicle.

  Introducing silica compounding components and energization components to reduce the above-mentioned noise has been devised, but it is necessary to evaluate how much noise is actually generated. Conventionally, after actually mounting tires on a vehicle, running on a dry road surface and charging static electricity, it passes through the manhole and discharges static electricity to determine how much noise will interfere with radio reception. I was evaluating. However, since the generation of static electricity depends on the weather and humidity, outdoor evaluation has been limited in terms of time and time. In addition, since the amount of static electricity generated varies depending on temperature and humidity, reproducible evaluation is difficult.

  Therefore, an object of the present invention is to provide a vehicle charging potential evaluation method that can be evaluated without being influenced by weather or humidity.

In order to solve the above problems, the evaluation method of the present invention stops a vehicle equipped with tires in a measurement chamber controlled to a predetermined temperature and humidity,
One tire of the vehicle is placed on a drum whose outer periphery is coated with an insulator,
Insulate all other tires of the vehicle from the floor of the measurement chamber;
The vehicle charging potential evaluation method is characterized in that after the tire on the drum is rotated by the drum, the charging potential of the vehicle is measured.

  Static electricity can be generated from only one tire with the vehicle insulated from the floor, and the evaluation is performed in a measurement room controlled to a predetermined temperature and humidity, so the tire is evaluated without being influenced by the weather. be able to. In the present application, humidity refers to relative humidity.

  Hereinafter, embodiments of an evaluation method according to the present invention will be described with reference to the drawings. FIG. 1 is an external view showing the evaluation method of the present invention. The vehicle 10 is stopped in a measurement chamber (not shown) controlled to a predetermined temperature and humidity. Tires 12 and 13 are mounted on the rim 11 of the vehicle 10. The rim 11 is a standard rim, and the tires 12 and 13 are filled with a standard internal pressure.

  The tire 13 of the left front wheel is placed on the drum 31. A sheet-like insulator 21 is inserted between all the remaining tires 12 and the floor 50, and the tire 12 is electrically insulated from the floor 50. Has been. The outer periphery of the drum 31 is covered with an insulator 32. Therefore, the vehicle 10 including the tires 12 and 13 is electrically insulated from the floor 50.

  When the drum 31 is rotated in such a state, the tire 13 rotates and static electricity is generated due to friction between the tire 13 and the insulator 32 of the drum 31. Since the vehicle 10 is insulated from the floor 50, static electricity is not discharged and the tire 13 and the body 30 of the vehicle 10 are gradually charged. The charging potential of the body 30 of the vehicle 10 is measured while the tire 13 is rotated for a predetermined time (for example, 15 minutes). If the charging potential is high, it can be seen that a large amount of static electricity is charged.

The size of the insulator 21 may be larger than the ground contact surface of the tire 12, but is preferably 1.5 times or more of the ground contact area, and the thickness is preferably 0.3 cm or more. The thickness of the insulator 32 is preferably 0.2 cm or more. The volume resistivity of the insulators 21 and 32 is preferably 10 ¹³ Ω · cm or more. As long as it has insulation, the material of the insulators 21 and 32 is not particularly limited, but the insulator 21 is preferably rubber, and the insulator 32 is preferably epoxy resin.

  From the viewpoint of facilitating the generation of static electricity, the temperature of the measurement chamber is preferably 30 degrees or less and the humidity is 40% or less. The insulator 32 preferably has a surface roughness such that the contact area with the tire 12 is 10 to 25% of the actual area.

  Three types of tires A to C (size: 215 / 55R17) having different electrical conductivities were made as prototypes, and static electricity was generated from the tires by the evaluation method of the present invention to evaluate the charging potential of the vehicle. Evaluation was also performed by a conventional evaluation method. Each evaluation method is as follows. The vehicle used was a rear-wheel drive sedan type passenger car.

(Evaluation method of the present invention)
As shown in FIG. 1, a vehicle equipped with tires was stopped in a measurement chamber controlled at a temperature of 19 degrees and a humidity of 32%. As an insulator 21 to be inserted between the tire 12 and the floor 50, an insulator having a size of 100 cm × 100 cm, a thickness of 0.3 cm, and a volume resistivity of 10 ¹³ Ω · cm (manufactured by Yotsugi Co., Ltd., product name: anti-static rubber sheet YS- 132-1-1) was used. The drum 31 was a steel drum having a diameter of 3 m, which is usually used for testing tires, and was coated with an epoxy resin having a thickness of 0.2 cm (product name: ARALDITE AW106J, manufactured by Nagase Ciba Co., Ltd.) as the insulator 32. The insulator 32 is obtained by casting an epoxy resin on an asphalt road surface. The surface roughness is such that the contact area with the tire 12 is 17% of the actual area, and the volume resistivity is 10 ¹³ Ω. -There was cm.

  After the drum 31 was rotated at 40 km / h for 15 minutes, the charged potential at the center of the door of the vehicle 10 (the portion indicated by x in FIG. 1) was measured while the drum 31 was rotated. The charging potential was measured with a charging potentiometer (manufactured by Kasuga Denki Co., Ltd., model number: KSD-0102).

(Conventional evaluation method)
After traveling on a dry road surface for 15 minutes at 40 km / h, sensory evaluation was performed on the noise that passed through the manhole and was received by the radio (frequency with broadcast of 1332 kHz) installed in the vehicle 10. At this time, the temperature was 18 degrees and the humidity was 33%.

(Evaluation results)
The evaluation results are shown in Table 1. According to Table 1, there is a correlation between the charging potential of the vehicle measured by the evaluation method of the present invention and the result of the conventional evaluation method. Therefore, the charging state of the vehicle can be evaluated indoors without being influenced by the weather and humidity.

It is an external view which shows the evaluation method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Vehicle 11 Rim 12, 13 Tire 21 Insulator 31 Drum 32 Insulator

Claims (1)

Stop the vehicle equipped with tires in a measurement room controlled to a predetermined temperature and humidity,
One tire of the vehicle is placed on a drum whose outer periphery is coated with an insulator,
Insulate all other tires of the vehicle from the floor of the measurement chamber;
A vehicle charging potential evaluation method, comprising: measuring a charging potential of the vehicle after rotating a tire on the drum by the drum.

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