Air spring

#The present invention relates to an air spring, and more particularly to an air spring that can suppress the increase in its weight and ensure the air tightness of a diaphragm more reliably.

#In a railroad vehicle, an air spring is arranged between a vehicle main body and a bogie to reduce the impact and vibration applied to the vehicle body while the vehicle is running. The air spring mainly includes an upper surface plate connected to the vehicle main body side, a lower surface plate arranged below the upper surface plate, and a rubber diaphragm arranged to connect the upper surface plate and the lower surface plate, and by elastic deformation of the diaphragm, the air spring can reduce the impact and vibration in the vertical direction during running. Examples of a sealing method for ensuring the air tightness of the diaphragm in the air spring include a fastening sealing method in which the diaphragm is sandwiched between the upper surface plate and one fastening fitting as well as between the lower surface plate and the other fastening fitting, and the diaphragm is fastened by bolts (refer to, for example, Miyamoto, “Illustrated Description of Mechanism of Train-Thorough Elucidation of Commuter Train-”, 2nd edition, Toyokuni Printing Co., Ltd., January, 2010, p. 46 (NPD 1)), a self-sealing method in which the diaphragm is fixed to each of the upper surface plate and the lower surface plate by using the inner pressure of the diaphragm (refer to, for example, “Spring Rigging for Railway Rolling Stock JISE 4206”, Japanese Industrial Standards Committee, May, 1989, p. 8, 10-12 (NPD 2)), and the like.

#NPD 1: Miyamoto, “Illustrated Description of Mechanism of Train—Thorough Elucidation of Commuter Train-”, 2nd edition, Toyokuni Printing Co., Ltd., January, 2010, p. 46 NPD 2: “Spring Rigging for Railway Rolling Stock JISE 4206”, Japanese Industrial Standards Committee, May, 1989, p. 8, 10-12

#FIG. 1 is a schematic view showing a structure of an air spring.

#FIG. 2 is a schematic view showing a structure of a diaphragm of the air spring.

#FIG. 3 is an enlarged schematic view of the structure of the air spring.

#Embodiments of the present invention will be described hereinafter with reference to the drawings, in which the same or corresponding portions are denoted by the same reference numerals and description thereof will not be repeated.

#In the beginning, a structure of an air spring according to a comparative example will be described. A structure of an air spring 100 according to one comparative example will be described first. Referring to FIG. 7, in air spring 100, a diaphragm 500 is sandwiched between an upper surface plate 110 and a fastening fitting 800 as well as between a lower surface plate 200 and a fastening fitting 810, and diaphragm 500 is fastened by bolts. In air spring 100, the air tightness of diaphragm 500 is ensured, while it is necessary to use heavy-weight fastening fittings 800 and 810, which leads to an increase in overall weight of the air spring disadvantageously. It is also necessary to apply uniform force to a sealed portion of diaphragm 500 and fasten diaphragm 500 in order to prevent the air leakage, which leads to an increase in the number of components such as bolts. In addition, stress relaxation (creep) occurs in the sealed portion of diaphragm 500, and thus, torque management during fastening is difficult and the assembly work requires a technique.

#Next, a structure of an air spring according to another comparative example will be described. Referring to FIG. 8, in this air spring, diaphragm 500 is fixed to upper surface plate 110 by using the inner pressure of diaphragm 500. In this air spring, it is difficult to ensure contact between diaphragm 500 and upper surface plate 110 in the case where the external force is applied in the deflated state with low inner pressure of diaphragm 500 due to vibration during transportation or handling during inspection, in the case where diaphragm 500 is significantly deformed due to large displacement applied from the horizontal direction while the vehicle is running, or in the other cases. Therefore, as shown in FIG. 9, diaphragm 500 falls off from upper surface plate 110 and the air leakage takes place from between diaphragm 500 and upper surface plate 110, disadvantageously. In order to deal with the aforementioned air spring according to the comparative example, an air spring according to the present embodiment is an air spring that can suppress the increase in its weight and ensure the air tightness of the diaphragm more reliably as described below.