Air spring

Details Air spring Air spring

1999-06-15

2001-07-10

Oberleitner, Robert J. (Department: 3613)

Spring devices

Vehicle

Comprising compressible fluid

C267S064270, C267S122000, C267S035000

Reexamination Certificate

active

06257561

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to an air spring having a height adjusting means for keeping constant the compressive deformation (or stroke).
When the treads of wheels of a railroad car are worn, they have to be reground. When they are reground, the car height reduces. With the railroad car having air springs, it is ordinary to increase its height to the original level after regrinding of the treads by interposing a shim between each air spring and the chassis of the car to keep constant the compressive stroke of the air springs to prevent changes in properties due to changes in the stroke.
An air spring proposed in unexamined Japanese patent publication 9-89029 has an upper and a lower face plate having stopper member's opposing each other. Each stopper member has a flat surface and a protrusion protruding toward the opposing stopper member. One of the stopper members is turnable.
With this air spring, the upper limit of the compression stroke when the protrusion of one of the stopper members is opposed to the flat surface of the other stopper member is equal to the upper limit of the compression stroke when said one of the stopper members is turned until the protrusions of both stopper members face each other and the air spring is inflated until its height increases by an amount equal to the height of the protrusions. Thus, by turning the stopper member during car height adjustment with the height of the protrusions of the stopper members adjusted to a value equal to the amount of car height adjustment, it is possible to maintain the same compression stroke after the car height adjustment as before.
In order to raise the entire air spring by interposing a shim, the air spring has to be dismounted from the chassis. This method is thus troublesome.
The two relatively turnable stopper members of the air spring of unexamined Japanese patent publication 9-89029 function as a kind of built-in shims. With this air spring, too, in order to turn one of the stopper members, the air spring has to be dismounted from the chassis. Height adjustment is thus troublesome.
An object of this invention is to solve these problems.
SUMMARY OF THE INVENTION
According to this invention, there is provided an air spring comprising an inner member, an outer cylinder, a bellows provided between the inner member and the outer cylinder, a stopper provided in the bellows and supported on the inner member and having a downward movement restricting portion for restricting the downward movement of the outer cylinder, a lower plate supporting the inner member, a rotating means provided on the stopper so as to extend outwardly through the space between the inner member and the lower plate for turning the stopper, the outer cylinder being formed with at least two circumferentially arranged supported surfaces, each provided at a different level from the other so as to face the respective downward movement restricting portion of the stopper, the stopper being turnably and airtightly mounted between the inner member and the lower plate, whereby the downward movement restricting portion is moved from a position facing one of the supported surfaces to a position facing another of the supported surfaces when the stopper is turned by a predetermined angle.
With this air spring, the restriction of lowering of the outer cylinder by the stopper is preferably carried out at a plurality of points. In order to prevent undue rotation of the stopper due to vibrations, it is preferable to provide a disengagable rotation preventive means for preventing rotation of the stopper by engaging the stopper turning portion at a front and a rear position of rotation of the stopper.
If the circumferentially arranged supported surfaces comprise a first and a second surface, when the stopper is rotated so that the movement restricting surface of the stopper moves from the position where it faces the first surface to the position where it faces the second surface, the compression stroke changes from S to (S−h), where h is the difference in height between the first and second surfaces. The upper limit of the compression stroke after the stopper has been rotated returns to S if the height of the air spring is increased by h. Thus, after the tread of the wheel has been reground such that the car height decreases by h, it is possible to reincrease the car height to the original level by increasing the height of the air spring and to absorb any increase in the compression stroke due to an increase in the height of the air spring by turning the stopper. This eliminates the need for an external shim for increasing the height of the mouting surface.
Also, according to this invention, since the stopper is provided with an outwardly protruding stopper turning portion, the stopper can be turned from outside. Thus, there is no need to dismount the air spring from the chassis to turn the stopper.
Other features and objects of the present invention will become apparent from the following description made with reference to the accompanying drawings, in which:


REFERENCES:
patent: 5921532 (1999-07-01), Pierce et al.
patent: 48-9743 (1973-03-01), None
patent: 48-35663 (1973-10-01), None
patent: 56-119003 (1980-02-01), None
patent: 61-116111 (1986-06-01), None
patent: 4-262103 (1992-09-01), None
patent: 9-89029 (1997-03-01), None

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