Measuring and testing – Vibration – By mechanical waves
Reexamination Certificate
1999-08-30
2001-05-01
Larkin, Daniel S. (Department: 2856)
Measuring and testing
Vibration
By mechanical waves
C267S064110, C267S064190, C267S064270, C267S064280
Reexamination Certificate
active
06223600
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an air spring having an ultrasonic measuring device for making distance measurements within the air spring.
BACKGROUND OF THE INVENTION
Air springs are mounted between the axle and the chassis as supporting parts in a vehicle. The distance between the chassis and the axle should not change even for different loading conditions. For this reason, it is necessary to measure the air spring height and to readjust the system by pumping and venting air when there are deviations.
Methods for ultrasonic distance measurements are utilized in various areas. Air ultrasonic distance measurements are used, for example, for fill level measurements of vessels, to measure rooms in a building, to measure distance when parking a motor vehicle and to measure distance in autofocusing photo apparatus, et cetera.
Various ultrasonic distance measurement devices have been suggested for determining distances within air springs.
An ultrasonic sensor within an air spring is described for use in a vehicle in German patent publication 3,620,957. In U.S. Pat. No. 4,798,369, an air spring control system is shown which is based on ultrasonic sensors in the form of transducers for measuring spring elevation. The advantages of using ultrasound within an air spring is that no turbulence of the sound waves is possible because of the air stream and that a very good range of the ultrasonic wave is possible even at higher frequencies in the overpressure present in the air spring.
An ultrasonic sensor, which is built into the air spring, for measuring elevation can be disturbed when high frequency sonic oscillations occur when filling and/or venting the air spring. The sonic oscillations are caused because, when the valves are opened, a pressure wave runs into the air spring and flow noises occur at the connecting pieces and these flow noises have a frequency which reaches up to and into the ultrasonic range. A possibility for reducing these disturbances is to reduce the flow velocity, for example, by reducing the cross section of the air line. However, this possibility presents the disadvantage that the lifting and lowering operations take place only very slowly.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an air spring having a device for making ultrasonic measurements wherein the disturbing ultrasonic oscillations, which occur when filling and venting the air spring, are avoided. It is another object of the invention to provide an air connection for such an air spring.
The air spring arrangement of the invention has a device for making ultrasonic distance measurements and includes: an air spring defining an interior space; a source of pressurized air; a connecting assembly for connecting the source to the air spring; the connecting assembly including: a supply line connected to the source; and, a connecting unit for connecting the supply line to the air spring; and, the connecting unit including: a connecting pipe stub having a first end connected to the supply line and a second end opening into the interior space of the air spring; the connecting pipe stub having an interior wall surface; and, a mesh layer lining the interior wall surface.
The solution provided by the invention is realized in an arrangement wherein a spin flow is generated in an air inlet pipe stub of the air spring whereby the velocity in the peripheral region of the air flow is reduced. In this way, the generation of disturbing ultrasonic oscillations is reduced at the tear-away edges without materially deteriorating the air throughflow.
The air connecting stub provided in accordance with a feature of the invention is lined on its inner wall surface preferably with a plastic net or mesh whose filaments are slightly inclined referred to the longitudinal center axis of the pipe stub. In this way, the velocity of the air flow in the peripheral region is reduced and the occurrence of ultrasonic disturbances is diminished.
The flow velocity is already reduced at the transition of the hose to the air connecting stub when the diameter of the stub is greater than that of the air hose. The filaments of the mesh are welded to each other at their crossover points in order that the filaments of the plastic mesh can present a reliable resistance to the intense air flow. A slippage of the plastic mesh out of the air connecting stub is prevented by a holding nose at the air spring end of the air connecting stub.
The end segment of the air connecting stub is formed to have a holding nose. With this holding nose, a possibly occurring acoustic defective adaptation between the stub and the interior space of the air spring can be reliably avoided.
REFERENCES:
patent: 3584845 (1971-06-01), Hoffman
patent: 4798369 (1989-01-01), Geno et al.
patent: 5859692 (1999-01-01), Ross, Jr. et al.
patent: 5936161 (1999-08-01), Fischer
patent: 6032535 (2000-03-01), Fischer et al.
patent: 6073491 (2000-06-01), Fischer et al.
patent: 3423602 A1 (1986-01-01), None
patent: 3620957 (1987-01-01), None
patent: 197 01 713 C1 (1998-08-01), None
patent: 197 01 712 C1 (1998-08-01), None
patent: 362055207 (1987-03-01), None
patent: 404266632 (1992-09-01), None
Altsinger Roland
Fischer Norbert
Contitech Luftfedersysteme GmbH
Larkin Daniel S.
Miller Rose M.
Ottesen Walter
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