Spring devices – Vehicle – Comprising compressible fluid
Reexamination Certificate
1998-05-01
2001-03-13
Oberleitner, Robert J. (Department: 3613)
Spring devices
Vehicle
Comprising compressible fluid
C267S122000, C267S124000
Reexamination Certificate
active
06199837
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The invention relates to air actuators, including air springs. More particularly, the invention relates to thermoplastic elastomeric air springs having a molded part containing a cap or piston and a rolling membrane all of which are of a nonreinforced construction that is injection or blow molded, where the integral cap and/or piston of the assembly may include integral interface clips for attachment to machinery or brackets, and where a separate cap or piston is attachable to the molded part to complete the air spring assembly. Specifically, the invention is a thermoplastic elastomeric nonreinforced air spring of an injection or blow molded design with an integral cap and/or piston having integral interface clips thereon where the air spring includes a thick rigid housing with an integral snap-fit therein, a thick rigid piston with an integral snap-fit therein where the thick rigid piston has a lesser diameter than the thick rigid housing and is seatable therein, and a thin rolling membrane extending between the thick rigid piston and the thick rigid housing, thereby defining an internal fluid pressure chamber that is pressurizable with a compressed fluid when an end cap is welded to the thick rigid housing.
2. Background Information
Pneumatic assemblies such as air actuators and springs have been used for many years for various purposes. The air actuator usually consists of a flexible rubber sleeve or bellows containing a supply of compressed fluid and a feed for increasing or decreasing the compressed fluid therein. The flexible sleeve is formed of a flexible elastomeric material often containing reinforcing cords, where the flexibility of the material permits a first end cap to move axially with respect to another end cap secured within the ends of the sleeve as the amount of compressed fluid is changed. Since the air actuator is positioned in between a movable or actuatable object and typically a fixed object, the movable object moves in correlation to this axial movement.
As to pneumatic springs, commonly referred to as air springs, the construction is similar with a flexible rubber sleeve or bellows containing a supply of compressible fluid. However, the air spring has one or more pistons movable with respect to the flexible sleeve. This piston causes compression and expansion of the fluid within the sleeve as the sleeve stretches or retracts, respectively, thereby absorbing shock loads and/or dampening vibrations. The flexible sleeve is formed of a flexible elastomeric material containing reinforcing cords and this permits the piston to move axially with respect to another piston or end cap secured within open ends of the sleeve. One application for such air springs is with motor vehicles where the spring provides cushioning between movable parts of the vehicle, primarily to absorb shock loads impressed on the vehicle axles by the wheel striking an object in the road or falling into a depression.
The general state of the art in this industry of air springs involves the current technology of the flexible sleeve being constructed of rubber that is reinforced with nylon cord. This nylon reinforced rubber sleeve must be attached in some manner to the piston or end caps on each end; which is presently accomplished by various forms of clamp assemblies. However, often these clamp assemblies present a problem in that ineffective sealing and/or clamping of the flexible sleeve to the end caps causes a lack of an airtight seal, which is critical to the functioning of an air spring.
In addition, another problem with existing air actuators and springs is the requirement of reinforcing the rubber sleeve with nylon or equivalent reinforcing cords. This reinforcing step adds extra expense and time to the manufacturing process of the overall air spring.
These and other problems and disadvantages exist in the current technology of air springs and air actuators. One of skill in the art will recognize and understand the above listed problems as well as others not described at this time. For this reason, a new and improved air spring and/or air actuator is needed having the objectives and advantages listed below.
SUMMARY OF THE INVENTION
Objectives of the invention include providing an improved air spring and/or air actuator.
A further objective of the invention is to provide such an improved air spring and/or air actuator which is constructed out of improved materials such as thermoplastic elastomers.
A further objective of the invention is to provide such an improved air spring and/or air actuator in which all of the housing, sleeve, and pistons and/or end caps are manufactured out of a nonmetallic material, and preferably out of a thermoplastic elastomer.
A further objective of the invention is to provide such an improved air spring and/or air actuator having a flexible membrane or sleeve made out of a material not requiring reinforcing cord such as nylon.
A further objective of the invention is to provide such an improved air spring and/or air actuator of an improved construction in which the thin rolling flexible membrane or sleeve is integrally attached to the rigid housing and/or end cap and the rigid piston actuatable therein.
A further objective of the invention is to provide such an improved air spring and/or air actuator that is substantially one integrally molded piece, that is, that has a rigid housing and a rigid piston that are integrally attached by a rolling membrane.
A further objective of the invention is to provide such an improved air spring and/or air actuator that is substantially one integral piece comprising a rigid housing and rigid piston connected by a rolling membrane all of which are injection or blow molded.
A further objective of the invention is to provide such an improved air spring and/or air actuator in which the end cap that closes the rigid housing to form the internal fluid pressure chamber is welded or otherwise affixed to the thick rigid housing in a leak-proof and pressurizable manner.
A further objective of the invention is to provide such an improved air spring and/or air actuator in which the snap-fit connections are integrally positioned within each of the end cap and piston so as to function as interface clips for assembly to machinery and/or bracketry.
A further objective of the invention is to provide such an improved air spring and/or air actuator that is economical to make for use in low cost air actuating environments.
These objectives and advantages are obtained by the improved air spring of the present invention, the general nature of which may be stated a s including an integrally molded body and an integrally molded cap. The integrally molded body includes a thin walled, flexible membrane extending between a thick walled, rigid housing and a thick walled, rigid piston thereby defining an internal chamber open only at an end of the housing opposing the piston, whereby the flexible membrane selectively rolls as the housing and piston are axially moved to an d away from one another. The integrally molded cap is attachable within the open end to enclose the internal chamber.
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Hoffman Keith E.
Jr.
Leonard Daniel J.
Tazewell Joseph L.
Bridgestone/Firestone Inc.
Jr.
Lipka Pamela J.
Oberleitner Robert J.
Sand Michael
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