JPS6248102B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in rubber membranes in air springs for use in railway vehicles, automobiles, industrial machinery, and the like.

Conventionally, as is well known, air springs come in bellows type, diaphragm type, and a mixture of both types, depending on the application, and all types of air springs are equipped with a rubber membrane to seal air inside. The rubber membrane usually consists of three layers: an inner rubber layer, an intermediate reinforcing layer, and an outer rubber layer. The intermediate reinforcing layer is made of polyester or nylon that can withstand air pressure, has excellent flexibility, and has good adhesion to rubber. Reinforcement cords such as the following are stacked in a biased manner.

In other words, when manufacturing a rubber membrane, a set of two reinforcing cord cloths with a certain intersection angle are pasted one after another on the inner layer rubber pasted on a former, etc.
Usually one set (called 2-ply), or two or three sets to make it even stronger, are manufactured in one piece by pasting an outer layer of rubber on top, followed by molding and vulcanization (heating). Thus, the intermediate reinforcing layer is laminated uniformly over the entire circumference except for the overlapping portion of the reinforcing cord cloth.

However, depending on the usage condition of the air spring, for example, in the front-rear direction and the left-right direction,
In some cases, the amount of displacement or permissible displacement that acts in the horizontal directions perpendicular to each other may be different. For example, in the case of a large displacement type (also referred to as the dynamic type) air spring for a so-called bolsterless bogie in a railway vehicle, Fig. 1 shows As shown, the small diameter end of the diaphragm rubber membrane 1 is fitted to the upper outer periphery of the inner cylinder 2, and the larger diameter end is attached to the lower outer periphery of the top plate 3 using the self-sealing structure or clamp structure shown in the figure. , the inner cylinder 2 is attached to the bogie frame side, and the top plate 3 is attached to the car body side, and a large front and back displacement of 100 mm or more, sometimes as much as 200 mm, is caused by the rotational displacement between the car body and the bogie frame when the vehicle passes through a curved road. In this case, the air spring's horizontal displacement perpendicular to the longitudinal direction, that is, the left-right displacement, is usually about 30 mm, which is extremely small compared to the longitudinal displacement.

On the other hand, the tension T acting on the rubber membrane 1 when using the air spring is given by T = P, R, where P is the internal pressure and R is the radius of curvature of the rubber membrane 1. When the internal pressure P is the same, the radius of curvature R is The larger the tension T, the larger the tension T. In the large displacement air spring, the radius of curvature R of the rubber membrane 1 is increased in order to increase the allowable amount of displacement in the front-rear direction, and as shown by the chain line, in the state of maximum displacement in the front-rear direction, , the radius of curvature R on the pulled side of the rubber film 1 becomes even larger, so that the rubber film 1
The tension in the front-rear position is much larger than in the left-right position.

However, in conventional rubber membranes, as mentioned above, the intermediate reinforcing layer has uniform strength over the entire circumference, so thick reinforcing cords or the number of multilayer reinforcing cords are used to obtain the necessary strength in the longitudinal direction. This results in an unnecessarily large reinforcing cord layer in the left and right positions, which increases the rigidity of the rubber membrane, which should be flexible, and has the disadvantage of deteriorating the performance of the air spring.

In order to solve the above-mentioned drawbacks of the conventional art, the present invention aims to provide a layer of reinforcing cords based on whichever of the horizontal directions orthogonal to each other when using an air spring, such as the front-back direction and the left-right direction, has a smaller amount of displacement, such as the left-right direction. The present invention provides a rubber membrane for an air spring, characterized in that the number of laminated reinforcing cords in the front-rear direction perpendicular to the left-right direction is increased according to the amount of displacement in the front-rear direction; The explanation will be based on the drawings.

FIG. 2 is a schematic developed plan view of an intermediate reinforcing layer in a diaphragm rubber membrane, for example, for explaining an embodiment of the present invention. 1 set of reinforcing cord layers in the 90° range 2
In the longitudinal direction where the amount of displacement is large, the number of laminated reinforcing cords is 2 sets and 4 plies () within a center angle of 90 degrees.

To form the intermediate reinforcing layer in the rubber membrane, as shown in FIG. 3, first two plies are applied to the entire circumference, and two additional plies are added only in the front-rear direction.

FIG. 4 shows the second embodiment of the present invention.
In the schematic developed plan view corresponding to the figure, as shown in Fig. 5, first, the entire circumference is made up of two plies (), and then two sets of two plies with a center angle of 90° are placed 22.5 mm from the center line in the longitudinal direction to the left and right, respectively. Overlapping by shifting by 45 degrees, 6 plies () for a center angle of 45 degrees in the front-back direction.
There are 4 plies () in the diagonal 45° direction and 2 plies () in the left and right directions.

In order to avoid incorrect installation direction of the rubber membrane manufactured as described above, for example, an indication (for example, an arrow) indicating the number of layers of reinforcing cords in the front and rear direction is provided on the surface of the rubber membrane, or an inner cylinder and Alternatively, it is desirable to provide an uneven fitting part on the attachment part to the top plate or the like.

Since the present invention is constructed as described above, the necessary minimum strength is ensured in each direction of the entire circumference of the rubber membrane according to the amount of displacement thereof, and furthermore, reinforcement in the left and right directions, for example, which has conventionally been unnecessarily increased, is ensured. By reducing the number of cord layers, the stiffness of the rubber membrane can be reduced and a flexible air spring can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view showing an example of a conventional air spring structure, FIG. 2 is a schematic developed plan view of an intermediate reinforcing layer in a diaphragm-shaped rubber membrane, and FIG. 3 is an explanatory diagram of the same process as above, FIG. 4 is a schematic developed plan view corresponding to FIG. 2 in another embodiment of the present invention, and FIG. 5 is an explanatory diagram of the same process. 1: Rubber membrane, 2: Inner cylinder, 3: Top plate,,,
: Number of plies.

Claims (1)

[Claims] 1. A reinforcement cord for air springs of bellows type, diaphragm type, etc. has an angle that intersects with the vertical axis of the air spring and is continuous from the large diameter end to the small diameter end of the rubber film. A plurality of layers of reinforcing cords are set in accordance with the relatively small horizontal displacement in the direction and therefore a relatively small rubber membrane tension, and after forming the entire circumference of the rubber membrane with the plurality of layers of reinforcing cords, The horizontal displacement in the orthogonal front and rear directions is relatively large, and therefore a relatively large membrane tension is exerted. A rubber membrane for an air spring characterized by adding multiple layers of reinforcing cords that are continuous up to the small diameter end and have a section that breaks in the middle in the circumferential direction.