Air spring, in particular for an air spring system for a wheel axle of a vehicle

Abstract: An air spring, in particular for an air spring system for a wheel axle of a vehicle, comprising a rolling bellows (1), a first end edge (3) of which is connected, in a sealing manner, to an end plate (4) and a second end edge (6) of which is connected, in a sealing manner, to a piston (2) which is coaxial with respect to the rolling bellows, can be moved into and out of the rolling bellows in the axial direction of the rolling bellows, and along which the rolling bellows rolls during this movement, the piston being formed as a single part made from plastic, comprising an inner section (7) and a substantially cylindrical outer casing (8) which is arranged and joined to the inner section and along which the rolling bellows can roll. The inner section, on the side facing towards the end plate, is provided with an end section (10) which in the direction of the end plate extends beyond the outer casing, is integral with the rest of the inner section and is able to function as a stop which can strike against the end plate.

Description: The invention relates to an air spring, in particular for an air spring system for a wheel axle of a vehicle, comprising a rolling bellows, a first end edge of which is connected, in a sealing manner, to an end plate and a second end edge of which is connected, in a sealing manner, to a piston which is coaxial with respect to the rolling bellows, can be moved into and out of the rolling bellows in the axial direction of the rolling bellows, and along which the rolling bellows rolls during this movement, the piston being formed as a single part made from plastic; comprising an inner section and a cylindrical outer casing which is arranged around and joined to the inner section and along which the rolling bellows can roll. An air spring of this type is known in practice. In this known air spring, the piston is provided, on the side of the end plate, with a stop which projects towards the end plate with respect to the rest of the piston and can come into contact with the end plate. This stop may be made from plastic and is designed as a separate part which is connected to the rest of the piston by means of a screw connection. The object of the invention is to provide an air spring of simpler construction which is relatively inexpensive to produce. In the case of an air spring of the type referred to in the introduction, this object is achieved by the fact that the inner section, on the side facing towards the end plate, is provided with an end section which in the direction of the end plate extends beyond the outer casing, is integral with the rest of the inner section and is able to function as a stop which can strike against the end plate. The piston of the air spring according to the invention is relatively inexpensive to produce. Moreover, the air spring is easier to fit than the known air spring. Preferably, the inner section is cylindrical, and the outer casing is arranged coaxially around it. Further preferred embodiments of the air spring according to the invention are defined in the dependent claims. Below, the invention will be explained in more detail with reference to the drawing, in which the single figure shows a preferred embodiment of an air spring according to the invention, partially in longitudinal section and partially as a side view. The air spring which is shown in the figure and is intended in particular to be used in an air spring system for a wheel axle of a vehicle comprises a rolling bellows 1 and a piston 2 which is coaxial with respect to the rolling bellows 1, can be moved into and out of the rolling bellows in the axial direction of the rolling bellows 1 and along which the rolling bellows 1 rolls during this movement. A first end edge 3 of the rolling bellows 1 is connected in a sealing manner to an end plate 4. This end plate may be connected to a part 5, which is shown in very diagrammatic form, of a chassis of a vehicle, for example by means of a screw connection. A second end edge 6 of the rolling bellows 1 is connected in a sealing manner to the piston 2. The piston 2 is formed as a single part made. from plastic and comprises a central, cylindrical inner section 7 and a cylindrical outer casing 8 which is arranged coaxially around and is joined to the inner section and along which the rolling bellows 1 can roll. The piston may be connected to a bearing arm, which is mounted beneath the vehicle, of a vehicle axle. A part 9 of the bearing arm is shown in the figure. On the side facing towards the end plate 4, the cylindrical inner section 7 is provided with an end section 10 which, in the direction of the end plate, projects beyond the outer casing 8, is integral with the rest of the cylindrical inner section 7 and can function as a stop which is able to come into contact with the end plate 4. On the side facing towards the end plate 4, the end section 10 is provided with an end wall 11. Reinforcement ribs 12, which are preferably radially oriented, may be arranged inside the end section 10. The cylindrical inner section 7 with the end section 11 is joined to the cylindrical outer casing by means of a flange section 13 which extends substantially in the radial direction. To strengthen the joint between the flange section 13 and the inner section 7, radial reinforcement ribs 14 may be arranged in the corner area between the flange section 13 and the inner section 7. At the location of the transition between the flange section 13 and the cylindrical inner section 7 with end section 10, the second end edge 6 of the rolling bellows 1 is connected to the piston 2 in a sealing but removable manner. Such a connection can be achieved by causing the end edge 6 of the rolling bellows 1 to interact in a clamping manner with the end section 10 of the cylindrical inner section 7. The internal pressure in the rolling bellows 1 ensures that the corresponding edge part 16 of the rolling bellows is pressed against the piston 2. The radial flange section 13 and the adjoining end section 10 of the cylindrical inner section 7 may be provided with a passage 15 which on one side opens out on the outside of the end section 10 and on the other side opens out on that side of the flange section 13 which faces towards the end plate 4. In the normal position of use of the air spring, this passage 15 will be closed on one side by the end part 16 of the rolling bellows 1, which rests against the flange section 13. By means of this passage 15, it is possible to vent the air spring at its maximum length. The piston 2 is made, for example, from polyamide which, if necessary, is reinforced with fibres. However, other plastic materials may also be suitable.

Claims: Air spring, in particular for an air spring system for a wheel axle of a vehicle, comprising a rolling bellows, a first end edge of which is connected, in a sealing manner, to an end plate and a second end edge of which is connected, in a sealing manner, to a piston which is coaxial with respect to the rolling bellows, can be moved into and out of the rolling bellows in the axial direction of the rolling bellows, and along which the rolling bellows rolls during this movement, the piston being formed as a single part made from plastic, comprising an inner section and a substantially cylindrical outer casing which is arranged around and joined to the inner section and along which the rolling bellows can roll, characterized in that the inner section, on the side facing towards the end plate, is provided with an end section which in the direction of the end plate extends beyond the outer casing, is integral with the rest of the inner section and is able to function as a stop which can strike against the end plate. Air spring according to claim 1, characterized in that the end section is provided, on the side directed towards the end plate; with an end wall. Air spring according to claim 1 or 2, characterized in that that end edge of the cylindrical outer casing which lies on the side of the end plate is joined, via a flange section which extends substantially radially, to the inner section, which is preferably of cylindrical design. Air spring according to claim 3, characterized in that the second end edge of the rolling bellows, at the location of the transition between the radial' flange section and the cylindrical inner section having the piston, is connected to the piston in a sealing but removable manner. Air spring according to claim 3, characterized in that the radial flange section and the adjoining end section of the cylindrical inner section is provided with a passage which on one side opens out on the outside of the end section and on the other side opens out on that side of the flange section which faces towards the end plate.

Inventors: AALDERINK DERK GEERT, AALDERINK, DERK GEERT
Applicants: WEWELER NV, WEWELER NEDERLAND B.V.
Application year: 1999
Main classification: F16F9
IPC codes: F16F9