WO2012074458A1

WO2012074458A1 - Air spring, piston and vehicle

Info

Publication number: WO2012074458A1
Application number: PCT/SE2011/051410
Authority: WO
Inventors: Sami Teppola
Original assignee: Scania CV AB
Current assignee: Scania CV AB
Priority date: 2010-11-29
Filing date: 2011-11-23
Publication date: 2012-06-07
Anticipated expiration: 2013-05-29
Also published as: SE537362C2; EP2646707A1; BR112013012574A2; SE1051252A1

Abstract

An air spring (10) for a vehicle (50), comprising a roll bellows (12) with a pair of end-walls (16, 36) and delineating an air spring chamber (20), one of which end- walls (36) is configured as a piston (30) with a circumferential surface (34) to support a rolling lobe (14) of the bellows when the end-walls move towards and away from one another. According to the invention the piston (30) is configured as a pressure vessel, separate from the air spring chamber (20), for a compressed air system (70) of the vehicle (50).

Description

Air spring, piston and vehicle

TECHNICAL FIELD

The invention relates to an air spring for a vehicle, comprising a roll bellows provided with a pair of end-walls and delineating an air spring chamber, one of the end-walls being in the form of a piston with a circumferential surface for supporting a rolling lobe of the bellows when the end-walls move towards and away from one another. The invention relates also to a piston for such an air spring and a vehicle provided with at least one such air spring.

BACKGROUND Such air springs are commonly used in wheel suspensions of freight vehicles, e.g. trucks and tractor units. As well as providing good springing function when the vehicle is in motion, such air springs have also the advantageous function of being easy to reset to suit varying vehicle loads or different driving situations by being replenished with or drained of compressed air by a compressed air system of the vehicle. The end-walls serve to connect the opposite ends of the air spring to the components which need cushioning, and at least one of the end-walls may also have an inlet/outlet aperture for said replenishment and draining. The piston needs a relatively large diameter and axial length to be able properly to support the rolling lobe of the bellows throughout the air spring's range of movement.

SUMMARY OF THE INVENTION

An object of the invention is to expand the functions of an air spring of the kind indicated in the introduction without substantially altering its construction.

This is achieved by the features indicated in the claims set out below. According to a version of the invention, the piston is configured as a pressure vessel, separate from the air spring chamber, for a compressed air system of the vehicle. This makes it easy to save space by using the already existing space in the piston, which is otherwise inactive or shared with the air spring chamber, to partly replace the separate pressure vessels which form part of the compressed air system, and thereby release space in and reduce the weight of the vehicle. Taking it that a typical piston can accommodate about 5 litres of air suggests that between two and six air springs in a freight vehicle may represent a volume of compressed air corresponding to a separate pressure vessel of between 10 and 30 litres. The piston acting as pressure vessel may also serve as a local pressure source for the relating air spring and/or for neighbouring air springs, with the result that the compressed air can be distributed by short routes which result in small line losses and quick response times. The piston has an inlet/outlet aperture for receiving compressed air from and delivering it to the compressed air system. This aperture may be situated in the air spring's end-wall formed on the piston. The air spring will thus have two compressed air connections, one of them for the air spring chamber, the other for the piston configured as pressure vessel.

The piston may be formed of a pair of parts joined together, e.g. a pair of pressed shell-like parts which may be joined together by a welded connection. They may also be joined together by a flanged connection. The flanged connection may also connect one end of the roll bellows to the piston.

Other features and advantages of the invention may be indicated by the claims and the description set out below of embodiment examples. BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side view, with portions cut away, of a wheelshaft suspension of a vehicle with an air spring according to the invention;

FIG. 2 is a view obliquely from above in longitudinal section of an air spring according to the invention;

FIG. 3 is a view obliquely from above in longitudinal section of a piston for an air spring according to the invention;

FIG. 4 is a sectional view, with portions cut away, of a lower end section of another piston for an air spring according to the invention; and FIG. 5 is a sectional view, with portions cut away, of an upper end section of a further piston for an air spring according to the invention.

DETAILED DESCRIPTION OF EMBODIMENT EXAMPLES FIG. 1 depicts an example of using an air spring 10 according to the invention as spring element at one side of a chassis 52 for an only partly depicted vehicle 50 in which a frame member 54 of the chassis 52 supports a rear wheel suspension 60.

The wheel suspension 60 has a leaf spring package 64 with its one end connected pivotably to the frame member 54 via a beam bracket 56 and its other end connected to the frame member 54 via the air spring 1 0. A wheelshaft beam 62 is anchored between the ends of the spring package 64 and supports in an undepicted way a shaft for a likewise undepicted rear wheel. As further illustrated in FIG. 1 , the wheel suspension 60 may also comprise a shock absorber 66.

In the example depicted, the vehicle 50 may have two axles, in which case the rear wheel suspension 60 may have two air springs 1 0, i.e. one near to each rear wheel. In other undepicted types of axle arrangements with more wheel suspensions, the vehicle may have more, e.g. four or six, such air springs 1 0.

FIG. 2 depicts in more detail an air spring 10 according to the invention. The air spring 10 has in a known way an approximately tubular roll bellows 12 which in conjunction with an upper end-wall 16 and a piston 30 delineates an air spring chamber 20. More specifically, the upper end of the bellows 12 is sealingly connected to an edge region 18 of the end-wall 16, and its lower end is sealingly connected to an edge region 38 at an upper end or end-wall 32 of the piston 30. These sealing end-connections may be configured in some other known way than as in FIG. 2, e.g. the inner end-wall 32 of the piston 30 may be connected to a plate 32' (FIG. 3) which firmly clamps a thickened inner end 12' of the bellows against the piston 30 in the edge region 38. As further illustrated by FIG. 1 in conjunction with FIG. 2, the upper end-wall 16 of the air spring 10 may be connected to the frame member 54 via a mounting 58 and a number of threaded fastening elements 46, and its lower end-wall 36, i.e. the bottom of the piston 30, may be connected to the spring package 64 via a central threaded connection 44.

The air spring 10 performs its resilient function in a known way in that when the air in the air spring chamber 20 is alternately compressed and expanded during the vehicle's springing movements, a rolling lobe 14 of the bellows 12 moves to and fro, guided along a circumferential surface 34 of the piston 30. The spring chamber 20 of the air spring 10 has in a likewise known way an inlet/outlet aperture 22 connected via a connecting nipple 72 and a line 74 to a schematically depicted central compressed air system 70 of the vehicle 50. In the example depicted, the compressed air system 70 is controlled by a vehicle computer 80, but may also be controlled mechanically, to distribute compressed air to various consumers, e.g. one or more further air springs 10 of the vehicle 50. The piston 30 of the air spring 10 is configured as a pressure vessel, separate from the spring chamber 20, for the vehicle's compressed air system 70. The piston 30 thus likewise has an inlet/outlet aperture 40 which is similarly connected via a connecting nipple 76 and a line 78 to the central compressed air system 70. By means of undepicted other lines, pumps, valves etc. of the compressed air system 70 the piston 30 can be pressurised to store compressed air and deliver it to various consumers as necessary, e.g. the spring chamber 20, within the system 60. As illustrated in FIG. 3, the piston 30 may be composed of a pair of shell-like parts 30a, 30b, e.g. made of deep-drawn or roll-formed/pressure-turned steel plate, which are joined together by a circumferential weld 30c. The inlet/outlet aperture 40 may take the form of a pressed collar in the bottom 36 of the piston 30, and a central recess 42 pressed in the bottom 36 may have an internal thread for the central threaded connection 44 depicted in FIG. 1 .

As illustrated in FIG. 4, the two parts of the piston 30 may also be joined together by a flanged connection 30d with a seal, e.g. an O-ring 30d'. The lower part 30b may then serve as a cover which forms the bottom or lower end-wall 36 of the piston 30.

In FIG. 5, the upper part 30a of the piston 30 takes instead the form of a cover which serves as the piston's top or upper end-wall 32. As illustrated in FIG. 5, the parts 30a and 30b may be united by a rolled flanged connection 30e which also sealingly fastens the thickened inner end 12' of the roll bellows 12 to the piston 30.

The description set out above is primarily intended to facilitate comprehension, and no unnecessary limitations of the invention are to be inferred therefrom. The modifications which will be obvious to one skilled in the art from perusing the description may be effected without departing from the inventive concept or the scope of the claims set out below.

Claims

1 . An air spring (1 0) for a vehicle (50), comprising a roll bellows (12) with a pair of end-walls (16, 36) and delineating an air spring chamber (20), one of which end-walls (36) is formed on a piston (30) with a circumferential surface

(34) to support a rolling lobe (14) of the bellows when the end-walls move towards and away from one another, c h a r a c t e r i s e d in that the piston (30) is configured as a pressure vessel, separate from the air spring chamber (20), for a compressed air system (70) of the vehicle (50).

2. An air spring according to claim 1 , in which the piston (30) has an inlet/outlet aperture (40) for receiving compressed air from and delivering it to the compressed air system (70).

3. An air spring according to claim 2, in which the inlet/outlet aperture (40) is situated in the end-wall (36) of the air spring (10) formed on the piston.

4. An air spring according to any one of the foregoing claims, in which the

piston (30) is formed of a pair of parts (30a, 30b) joined together.

5. An air spring according to claim 4, in which the parts (30a, 30b) are joined together by a circumferential weld (30c).

6. An air spring according to claim 4 or 5, in which the parts (30a, 30b) are joined together by a flanged connection (30d, 30e).

7. An air spring according to claim 6, in which the flanged connection (30e) also connects an end (12') of the roll bellows (12) to the piston (30).

8. A piston (30) according to any one of the foregoing claims for an air spring (10) according to any one of the foregoing claims.

9. A vehicle (40) provided with a number of the air springs (1 0) according to any one of the foregoing claims.