Valves and valve actuation – Fluid actuated or retarded – Dashpot or fluid controlled retarder or timer
Patent
1997-12-23
1999-03-23
Lee, Kevin
Valves and valve actuation
Fluid actuated or retarded
Dashpot or fluid controlled retarder or timer
251 63, 251 635, F16K 31163
Patent
active
058848959
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention is based on an apparatus for time-dependent control of the regeneration time of an air dryer.
One such device is already known (European Patent Disclosure EP 0 036 569 A1) in which a spring-loaded piston connected to the shutoff valve is displaceable between two cylinder chambers of a cylinder by differential pressure. The two cylinder chambers communicate through throttle bores of different cross sections and with the interior of the air dryer. The compressed air they contain is used, along with the air taken from a supply air tank, to regenerate the air dryer. The known apparatus requires a relatively large amount of installation space. Moreover, the length of the regeneration phase is dependent on consumerdictated pressure fluctuations in the compressed air system as well as on production-related differences among the throttle bores.
ADVANTAGES OF THE INVENTION
The apparatus according to the invention is advantageous over the prior art in that the action of the throttle restriction is adjustable to very close tolerances. This can be done by modifying the structure of the membrane, or in other words its mean pore diameter, pore volume, effective membrane surface area, and membrane thickness. On the condition of replicable pressure conditions of the air penetrating the membrane, it is thus possible to attain a very accurate time-dependent control of the regeneration time. The regeneration of the air dryer is therefore controllable without unnecessary consumption of compressed air.
Based on a choice of material consistent performance of the membrane over the service life of the air dryer can be expected, since the material is largely resistant and dirt-repellent.
With a refinement of the device not only is the introduction of air into the hollow chamber achieved, but the sealing off of the piston from the hollow chamber is attained, if the air is positively displaced from the hollow chamber on its way through the membrane.
The embodiment of the invention defined herein is a space-saving way, that is also practical to produce and install, of combining the elements of the regeneration time control apparatus, which includes the delay device, the shutoff valve, and the actuating means.
Further advantages will become apparent from the ensuing description of the apparatus according to the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
One exemplary embodiment of the invention is shown in simplified form in the drawing and is described in further detail in the ensuing description.
FIG. 1 shows a circuit diagram of a compressed air system, shown only in part, with an air dryer, and
FIG. 2 shows a section through an apparatus for controlling the regeneration time of the air dryer.
DESCRIPTION OF THE EXEMPLARY EMBODIMENT
The circuit diagram in FIG. 1 shows a compressed air system 10, specifically both the energy supply and part of the transmission equipment of a brake system for utility vehicles. The compressed air system 10 has an air compressor 11 with a feed line 12 connected, thereto the feed line has in succession in the feed direction, a pressure controller 13, an air dryer 14, a one way check valve 15 and a guard valve 16. A supply tank 17 for compressed air of a consumer circuit, not otherwise shown, is connected to the guard valve 16. No other consumer circuits of the compressed air system 10 are shown here.
The air dryer 14 is a so-called single-chamber air dryer. It contains a drying medium, with which moisture-laden compressed air pumped by the air compressor 12 and arriving from being distributed to the consumer circuits, is dehumidified. The drying medium absorbs the moisture until its drying capacity is exhausted; this is why the air dryer 14 requires regeneration of its drying medium. To that end, an apparatus 20 for the time-dependent control of the regeneration time of the single-chamber air dryer 14 is provided. The regeneration time control apparatus 20 includes a shutoff valve 21, a pneumatic delay device 22, and a throttle 23. The shutoff valve 21 is in series wi
REFERENCES:
patent: 3116917 (1964-01-01), Cramer
patent: 4525183 (1985-06-01), Cordes et al.
patent: 4657224 (1987-04-01), Lattuada
patent: 4723476 (1988-02-01), Stucky
patent: 4987919 (1991-01-01), Boutin
Heizmann Klaus
Karthaeuser Klaus
Leopold Ruediger
Schnaeker Alois
Weller Rolf
Greigg Edwin E.
Greigg Ronald E.
Lee Kevin
Robert & Bosch GmbH
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