No abstract

A gear case used at a bogie of a rolling stock is an important part to pack a small gear and a large gear that pass the driving force from a main mortar to a wheel. An axle, to which the small gear and the large gear connect, is housed in a gear case through an axle bearing for rotation. The defect of the axle bearings can affect the running safety of rolling stock. In this context we investigate a sensor using a hanging rubber, which can detect of damage of axle bearing in gear case. The hanging rubber is used as a fixing device, which attaches the gear case firmly to the bogie frame. By using hanging rubber for sensor, it can be easily installed for bogie. In addition, the loss of the sensor installed on the bogie and the risk of impact with flying object can be reduce. The sensor using the hanging rubber is incorporated with a piezoelectric elements. The piezoelectric elements can convert mechanical energy to electric energy, and vice versa. The defection of axle bearing in gear case can be detect by the electric signal generated from piezoelectric elements. The rotation test by rotation testing machine of gear system with sensor using hanging rubber is carried out. As the result of rotation test with damaged and normal small gears, it is confirmed that the damage can be detected by amplitude of electric voltage from piezoelectric element when the rotation speed is higher than 50km/h. In case of the rotation speed is lower than 50km/h, the damage can be detected by the frequency analysis of time wave.

Since axle journal roller bearings of the bogie of rolling stock are important components for the running of the vehicles, early detection of damage to axle bearings is required. Therefore, we developed an autonomous damage detection system "ADDS" as one of the detection devices. The ADDS uses energy harvesting technology that utilizes the power generation function of the piezoelectric element "PZT". The ADDS can detect axle bearing damage and transmit obtained data to receiver that will be installed under floor of the vehicle without a power supply and cable connection from the vehicle body. In the ADDS, the antivibration rubber for axle springs, which is installed on the axle box is replaced by an autonomous damage detection antivibration rubber "ADDAR". The ADDAR contains the PZT as a power generation module "PGM" and a transmitter that transmits the detected data to receiver. The transmitter in the ADDAR can be driven by electric power from the PGM. The rotational test to evaluate the performance of the ADDAR was carried out using an axle journal bearing performance rig. The test results show that the power generation performance of the PGM of the ADDAR installed on the damaged axle bearing is higher than that of the ADDAR installed on the normal axle bearing. It is confirmed that the transmitter in the ADDAR installed on the damaged axle bearing can transmit the obtained data to the receiver. Additionally, the power generation performance of the ADDAR is improved when the PGM is installed directly above the damaged location of the axle bearing. In this case, the ADDAR can secure the power to drive the transmitter even at low rotational speeds.

No abstract

Aligned-type' piezoelectric rubber is a composite of piezoelectric ceramic, lead zirconate titanate (PZT) particles, which are aligned in a silicone rubber matrix. The aligned-type piezoelectric rubber has both elasticity and piezoelectricity. PZT, a piezoelectric ceramic, does not have elasticity. Also, piezoelectric polymers such as polyvinylidene difluoride (PVDF) have elasticity but can only form a thin film. The conventional aligned-type piezoelectric rubber (CAT) is as thin as about 2 mm, has a high spring constant. Therefore, a thick aligned-type piezoelectric rubber (TAT), having a thickness of 10 mm was fabricated by a new method, the "inversion method". The TAT was possible to reduce the spring constant to less than 1/5 of that of the CAT while maintaining the piezoelectricity (d33) equivalent to the CAT. Also, the d33 of the TAT is more than twice that of PVDF, and it is Young's modulus is less than 1/200 that of PVDF.