JP2005042852A - Sleeve type air spring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sleeve type air spring which can achieve the remarkable improvement of durability by delaying the occurrence of breakage such as cracking by reducing distortion applied to a rubber membrane or by reducing it half and by preventing the rubber membrane from being damaged in use under the condition that a severe rolling behavior is generated. <P>SOLUTION: The air spring is constituted as follows. A rolling guide member 11 has the same diameter or nearly the same diameter as that of the rolling guide peripheral face 4a of a piston 4 and the peripheral face 11a for guiding the rolling of the upper part 1u of the rubber membrane 1 when the rubber membrane 1 is elastically deformed. The rolling guide member 11 is provided to an upper face plate 2 side air-tightly connected to the upper bead part 1A side of the tubular rubber membrane 1. Bent parts 11a, 4a have outer diameters almost equal to the expanding outer diameter D of the rubber membrane 1 and are for storing and holding the upward and downward swelling deformation part of the rubber membrane 1 into a smooth curvilinear shape. The bend parts 11a, 4a are formed by curling to the upper end of the rolling guide peripheral face 11a and the lower end part of the piston 4. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an air spring used as, for example, a vehicle body suspension spring of an automobile. More specifically, compressed air is enclosed in a rubber film that is deformable from a reinforcing cord such as rubber and a weave fiber, and its air pressure and effective The present invention relates to a sleeve-type air spring configured to support a load equal to the product of the area and to perform a spring action using the compressibility of air.

  As shown in FIG. 4, this type of conventional general sleeve-type air spring includes a cylindrical rubber film 1 and a curling formed so as to enclose an upper (large diameter) bead portion 1A of the cylindrical rubber film 1. A lower bead portion is sandwiched and fixed from above and below by a plate-shaped upper surface plate 2 hermetically bonded to the rubber film 1 via the portion 2A and a lower (small diameter) bead portion 1B of the cylindrical rubber film 1 by a fastening bracket 3. A piston 4 having a circumferential surface 4a which is hermetically bonded to the 1B side and rolls and guides a lower portion 1d of the rubber film 1 when the rubber film 1 is elastically deformed; and an upper portion of the upper surface plate 2 and a lower portion of the piston 4 The fixing members 12 and 13 are fixed, and a stopper 5 that limits elastic deformation of the rubber film 1 beyond a certain level.

  As shown in FIG. 5, the rubber film 1 is composed of an inner layer rubber 6 and an outer layer rubber 7, and a plurality of layers of reinforcing cords 8 arranged in a biased manner between the inner and outer layer rubbers 6 and 7, and The bead ring in which both end portions of each reinforcing cord 8 (only the end portion on the top plate 2 side is shown in FIG. 5 but the end portion on the piston 4 side is the same) are embedded in each bead portion 1A, 1B. It was constructed by wrapping around 9, 10 and folding back to the outer surface side of the rubber film 1 and bonding the folded end portions (see, for example, Non-Patent Document 1).

“Automobile springs for trucks and buses” published by the Japan Society for Automotive Engineers, established on March 26, 1987, JASO C 613-87, p1-8

  In the sleeve type air spring having the rubber film structure as described above, when the vibration is inputted from the lower part of the piston 4 when used as a vehicle body suspension spring, the lower part 1d of the rubber film 1 is arranged around the piston 4. When the piston 4 moves up and down while being guided to roll on the surface 4a, a spring action of absorbing vibration is exhibited.

  In such a spring action, in the conventional sleeve type air spring configured so that only the lower portion 1d of the rubber film 1 is rolled and guided by the peripheral surface 4a of the piston 4, the rubber film 1 is repeatedly elastically deformed. For example, a large distortion is not only generated on the surface of the rubber film 1 due to repeated diameter changes in which the point A of the rubber film 1 shifts to the position of the point B and the position B shifts to the point A. Further, the reinforcing cord 8 disposed in a biased manner between the inner and outer layer rubbers 6 and 7 is extremely expanded and contracted, and the reinforcing cord 8 is likely to be greatly distorted. In particular, as shown in FIG. 5, the upper end portion 1u of the rubber film 1 has an end portion of a reinforcing cord 8 wound around the bead ring 9 embedded in the upper bead portion 1A and folded back to the outer surface side. Since there is a boundary portion that is located and serves as a strength changing portion of the rubber film 1 having a multilayer structure, strain concentrates on the boundary portion, causing early breakage such as cracks, resulting in breakage such as cracks. As this progresses, air leakage may occur, leading to a decrease or loss of the spring function.

  In particular, when used as a suspension spring for a low-floor automobile such as a bus or truck, the installation height is high with respect to the center of the vehicle roll, and the height difference between the rolling center of the air spring and the mounting surface of the piston 4 is large. In the usage mode, when bound, as shown in FIG. 6, the upper portion 1u of the rubber film 1 moves greatly and swells upward and deforms, and when rebounding, as shown in FIG. When 1u stretches and abnormal tension is applied and such behavior is repeated, breakage such as a crack is likely to occur at an early stage in the upper portion 1u. Further, when a rolling behavior with a large lateral displacement occurs, the upper portion 1u and the lower portion 1d of the rubber film 1 are placed on the edge portions of the upper and lower mounting members 12, 13 as shown by circles in FIG. There is a problem in durability when used under conditions where interference can easily cause scratches, and therefore severe rolling behavior can occur, such as suspension springs in low-floor automobiles.

  The present invention has been made in view of the above circumstances, and it is possible to reduce the strain applied to the rubber film under the same vibration input value or to reduce the generation time of breakage such as a crack by halving and tough rolling behavior. It is an object of the present invention to provide a sleeve type air spring that can prevent the rubber film from being damaged even when used under the generated conditions and achieve a remarkable improvement in durability.

  In order to achieve the above object, a sleeve-type air spring according to claim 1 of the present invention has an upper surface plate hermetically bonded to the upper bead portion side of the cylindrical rubber film and the rubber film on the lower bead portion side. A sleeve-type air spring in which a piston having a peripheral surface for guiding the rolling of the lower portion of the rubber film at the time of elastic deformation is hermetically joined, and mounting members are provided at the upper part of the upper plate and the lower part of the piston And a rolling guide member having a peripheral surface for guiding the rolling of the upper portion of the rubber film when the rubber film is elastically deformed, and the rolling guide of the rolling guide member. The upper end portion of the peripheral surface and the lower end portion of the piston have an outer diameter substantially equal to the outer diameter of the rubber membrane, and the curved portion that accommodates and holds the upper and lower bulging deformed portions of the rubber membrane in a smooth curved shape. Part formed curling And it is characterized in that is.

  A sleeve type air spring according to a second aspect of the present invention is the sleeve type air spring according to the first aspect, wherein the rolling guide circumferential surface of the piston and the rolling guide circumferential surface of the rolling guide member are provided. The same diameter or substantially the same diameter is set.

  A sleeve type air spring according to a third aspect of the present invention is the sleeve type air spring according to the first or second aspect, wherein the cylindrical rubber film is biased between an inner layer rubber and an outer layer rubber and between the inner and outer layer rubbers. The reinforcing cord is sandwiched in a shape, and both ends of the reinforcing cord are wound around the bead ring embedded in the upper and lower bead portions.

  According to the first aspect of the present invention, when the piston moves up and down in accordance with vibration input from the lower part of the piston, the lower part of the rubber film is guided to roll along the circumferential surface of the piston. Since the upper part of the roller is guided to roll along the peripheral surface of the rolling guide member, when the vibration input value is the same, the amount of movement of the rubber film is very small compared to the conventional air spring, or almost half. Therefore, the strain applied to the surface of the rubber film and the biased reinforcing cord can be reduced or halved. In addition, severe bounce that occurs when the installation height is high and the height difference between the rolling center of the air spring and the mounting surface of the piston is large, such as when used as a suspension spring for low-floor automobiles such as buses and trucks. Even during behavior and rebound behavior, it is possible to avoid the phenomenon of abnormal tension being applied due to large bulge deformation or stretching of the rubber film, and even when rolling behavior with large lateral displacement occurs, the rubber film can be moved upward and downward. The swollen deformed portion can be accommodated and held in a curvilinearly curved portion so as to prevent the deformed portion from interfering with and being damaged by the edge portions of the upper and lower mounting members. Therefore, even when used under conditions where severe rolling behavior may occur, such as suspension springs in low-floor automobiles, cracks and scratches occur in the rubber film due to distortion and buckling phenomenon applied to the rubber film. It is possible to suppress the occurrence of breakage and the like, maintain the original spring function for a long period of time, and significantly improve the durability of the entire air spring.

  In particular, when the rolling guide circumferential surface of the piston and the rolling guide circumferential surface of the rolling guide member are set to the same diameter or substantially the same diameter, the vibration absorption stroke should be increased by increasing the film length of the rubber film. It is possible to prevent the occurrence of early breakage such as cracks and scratches when used under severe conditions such as when used as a suspension spring for low floor vehicles such as buses and trucks, and the durability of the entire air spring Can be further improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall longitudinal sectional view of a sleeve-type air spring according to the present invention. This sleeve-type air spring 20 has a top plate 2 formed in a cup shape with a downward opening, and the cup-shaped top plate 2. On the side, a cylindrical rolling guide member 11 having a peripheral surface 11a for guiding the rolling of the upper portion 1u of the rubber film 1 when the rubber film 1 is elastically deformed is fitted and held. The upper bead of the rubber film 1 between the inner end portion 11b of the rolling guide member 11 and the lower end bent portion 2b of the cup-shaped upper surface plate 2 on the radially inner side of the rolling guide peripheral surface 11a Part 1A is clamped and fixed.

  The diameter D1 of the rolling guide circumferential surface 11a of the rolling guide member 11 and the diameter D2 of the rolling guide circumferential surface 4a of the piston 4 are set to be the same (D1 = D2), and their rolling guide circumferences. The lengths in the axial direction of the surfaces 11a and 4a are also set substantially equal, and the rubber film 1 is formed on the upper end portion of the rolling guide circumferential surface 11a of the rolling guide member 11 and the lower end portion of the rolling guide circumferential surface 4a of the piston 4. Curved portions 11b and 4b having an outer diameter substantially equal to the expanded outer diameter D and accommodating and holding the upward and downward bulging deformation portions of the rubber film 1 in a smooth curved shape are curled.

  In addition, since it is the same as that of the conventional sleeve type air spring shown in FIG. 4 except the above-mentioned structure, the same code | symbol is attached | subjected to a corresponding part and those detailed description is abbreviate | omitted. Further, since the structure of the rubber film 1 is the same as that of the conventional sleeve type air spring shown in FIG. 5, its description and illustration are omitted.

  In the sleeve-type air spring 20 configured as described above, when the piston 4 moves up and down with vibration input from the lower portion of the piston 4, the lower portion 1d of the rubber film 1 is the rolling guide circumferential surface 4a of the piston 4. When the vibration input value is the same, the upper part 1u of the rubber film 1 is rolled along the rolling guide circumferential surface 11a of the rolling guide member 11. Since the movement amount of 1 is almost half that of the conventional air spring, the strain applied to the surface of the rubber film 1 and the biased reinforcing cord 8 can be almost halved. The occurrence time of breakage such as a crack generated in the rubber film 1 due to the applied strain can be delayed.

  Further, since the rolling guide circumferential surface 4a of the piston 4 and the rolling guide circumferential surface 11a of the rolling guide member 11 are set to have the same diameter (D1 = D2), the length of the rubber film 1 is increased. The vibration absorption stroke can be increased, and the installation height of the air spring 20 is high as in the case of using as a suspension spring for a low floor automobile such as a bus or truck. 4, the upper portion 1 u of the rubber film 1 rolls along the rolling guide peripheral surface 11 a of the rolling guide member 11, as shown in FIG. 2. It is guided and bulges upward and does not deform. Further, at the time of rebound, as shown in FIG. 3, the upper portion 1 u of the same rubber film 1 is rolled and guided along the rolling guide circumferential surface 11 a of the rolling guide member 11 to apply abnormal tension due to tension. Therefore, the end portion of the reinforcing cord 8 is positioned at the upper portion 1u of the rubber film 1, and strain concentrates on the boundary portion that changes the strength in the rubber film 1 having a multilayer structure. Can be prevented.

  In addition, a curved portion having an outer diameter substantially equal to the expansion outer diameter D of the rubber film 1 at the upper end portion of the rolling guide circumferential surface 11 a of the rolling guide member 11 and the lower end portion of the rolling guide circumferential surface 4 a of the piston 4. By forming 11b and 4b, even when rolling behavior is accompanied by a large lateral displacement, the upper part 1u of the rubber film 1 has an upward bulging deformation part and the lower part 1d has a downward bulging part in a smooth curved shape. It is possible to prevent the bulging and deforming portions from interfering with the edge portions of the upper and lower mounting members 12 and 13 and being damaged. Accordingly, the durability of the air spring 20 as a whole can be significantly improved even when used under conditions where severe rolling behavior may occur, such as a suspension spring of a low-floor automobile. .

  In the above embodiment, the diameter D1 of the rolling guide circumferential surface 11a of the rolling guide member 11 and the diameter D2 of the rolling guide circumferential surface 4a of the piston 4 are set to be the same (D1 = D2). As described above, the relationship between the diameters D1 and D2 may be set to D1> D2, D2> D1, or D1≈D2.

1 is an overall longitudinal sectional view of a sleeve type air spring according to the present invention. It is a longitudinal cross-sectional view which shows the behavior at the time of bound of the sleeve type air spring. It is a longitudinal cross-sectional view which shows the behavior at the time of the rebound of the sleeve type air spring. It is the whole longitudinal cross-sectional view of the conventional sleeve type air spring. It is an expanded longitudinal cross-sectional view of the principal part of the conventional sleeve type air spring. It is a longitudinal cross-sectional view which shows the behavior at the time of bound of the conventional sleeve type air spring. It is a longitudinal cross-sectional view which shows the behavior at the time of the rebound of the conventional sleeve type air spring.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Cylindrical rubber film, 1A ... Upper bead part, 1B ... Lower bead part, 1u ... Upper part, 1d ... Lower part, 2 ... Upper surface plate, 4 ... Piston, 4a ... Rolling guide peripheral surface, 6 ... Inner layer Rubber, 7 ... Outer rubber, 8 ... Reinforcement cord, 9, 10 ... Bead ring, 11 ... Rolling guide member, 11a ... Rolling guide peripheral surface, 12, 13 ... Mounting member, 20 ... Sleeve type air spring, D ... Expansion outer diameter of rubber film, D1... Diameter of rolling guide circumferential surface 4a, D2... Diameter of rolling guide circumferential surface 11a.

Claims (3)

A piston having an upper surface plate hermetically joined to the upper bead portion side of the cylindrical rubber film and having a peripheral surface for guiding rolling of the lower portion of the rubber film when the rubber film is elastically deformed to the lower bead portion side In a sleeve-type air spring in which airtightly connected and mounting members are provided on the upper part of the upper plate and the lower part of the piston,
A rolling guide member having a circumferential surface for guiding the rolling of the upper portion of the rubber film when the rubber film is elastically deformed is provided on the upper surface plate side, and the rolling guide circumferential surface of the rolling guide member The upper end of the piston and the lower end of the piston have a curved portion that has an outer diameter substantially equal to the outer diameter of the rubber membrane and accommodates and holds the upward and downward bulging deformation portions of the rubber membrane in a smooth curved shape. A sleeve type air spring characterized by curling. The sleeve type air spring according to claim 1, wherein the rolling guide circumferential surface of the piston and the rolling guide circumferential surface of the rolling guide member are set to have the same diameter or substantially the same diameter. The cylindrical rubber film is composed of an inner layer rubber, an outer layer rubber, and a reinforcing cord sandwiched between the inner and outer layer rubbers in a biased manner, and both ends of the reinforcing cord are arranged around the bead ring embedded in the upper and lower bead portions. The sleeve type air spring according to claim 1 or 2, wherein the sleeve type air spring is wound.

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