Flow limiter

Details Flow limiter Flow limiter

1999-06-30

2001-04-17

Hook, James (Department: 3752)

Pipes and tubular conduits

With flow regulators and/or baffles

Restrictors

C138S046000

Reexamination Certificate

active

06216741

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a device for limiting the flow rate of a liquid.
2. Description of the Prior Art
Flow limiters are known wherein the control elements consist at least partially of elastomer material. Such known structures have the drawback that their control characteristics are not manageable and, even in the case of careful and accurate production, different flow limiters can possess highly diverse characteristics.
SUMMARY OF THE INVENTION
It is a first object of the invention to provide a flow limiter which combines a simple structure with characteristics which are predictable and manageable within narrow limits.
In respect of the above objective the invention provides a device for limiting the flow rate of a liquid, which device comprises:
a generally tubular, rotation-symmetrical housing with an inlet opening and an outlet opening for the liquid;
a first substantially rotation-symmetrical body which is guided for axial displacement and urged toward the inlet opening by spring means and which is located with the periphery of its widest part at a distance from the inner wall of the housing;
a generally annular second body disposed in stationary position on the inner wall of the housing;
wherein as the liquid flow increases the first body moves toward the second body while reducing the size of the passage in the gap defined by the first body and the second body;
which housing, which first body and which second body are form-retaining.
A specific embodiment has the special feature that the housing, the first body and the second body each consist of a form-retaining material, for instance metal such as aluminium, steel, stainless steel, or a hard plastic such as ABS, PPA, PA, POM, PP or the like. Combinations can also be applied.
The specific embodiment has the special feature that the first body has a shape narrowing toward the inlet opening, for instance a generally conical, spherical, parabolic or hyperbolic shape. The upstream surface or front surface of the first body can optionally also have a flat shape. A rotation-symmetrical, narrowing form can have the advantage of a more regular and better manageable symmetrical loading of the first body by the liquid flow, which can enhance management of the control characteristic.
Another embodiment has the special feature that the second body is interchangeable with a second body with dimensioning adapted to different technical requirements, The second bodies can together form a set, the different members of which carry specific information, for instance in the form of colour codes, corresponding to a specific control characteristic or a specific flow limiting value which can be realized with such a second body.
A particular embodiment of the device according to the invention has the feature that the second body has a number of passage openings ordered in a circle.
In accordance with another aspect of the invention, the device has the special feature that the gap is defined by respective co-acting surfaces with a form narrowing toward the outlet opening.
This latter embodiment can have the special feature that cylindrical steps are superimposed on the co-acting surfaces. A combination of the embodiment in which the second body has a circle of passage openings and the embodiment with the superimposed cylindrical steps can have the feature that the passage openings are situated in the zones between the cylindrical steps.
Very simple in terms of production technique is an embodiment wherein the second body is connected to the housing by a snap connection.
As an alternative to said passage openings, a variant of a device according to the invention can have the special feature that the second body has a number of recesses debauching on its inner surface and serving as flow channels.
The invention with the co-acting surfaces having shapes narrowing downstream can have the feature that the co-acting surfaces have shapes which are chosen so as to obtain a desired control characteristic, for instance substantially parabolic, substantially hyperbolic or other shapes causing progression or degression.
The spring means can be manufactured from any suitable material, for instance spring steel Or an appropriate plastic. According to a specific aspect of the invention the device has the feature that the spring means contain memory metal. Such an embodiment is particularly suitable for heat-exchanging installations. A multi-stage control path can be realized with such an embodiment. Energy losses can be limited herewith in heating systems. Such energy losses are often designated initial losses, starting and stopping losses.
According to a very advantageous aspect of the invention the device has the feature that in its rest position the first body presses sealingly against an elastic sealing ring which is connected fixedly to the inner surface of the housing and engages on the first body in the zone situated upstream of the widest part of the first body such that the device can also act as a non-return valve.
In a practical embodiment the device has the feature that the first body is supported by a stem which is slidable in a bush connected by one or more spokes to the second body or to the housing.
In a variant the device has the characterizing feature that the gap is defined by a surface of the first body narrowing in flow direction and the free end edges of a circle of lips formed curving toward this surface and having a common form narrowing in upstream direction such that as the flow rate increases the first body is displaced downstream and the lips bend elastically inward.
A specific embodiment has the special feature that the first body defines together with a foremost peripheral edge of the housing an at least more or less flat, annular inlet opening. A great effectiveness of the device can hereby be combined with a relatively small overall depth.
According to another aspect of the invention the device has the special feature that a plate disposed fixedly relative to the housing is situated upstream of the first body. This plate acts in a certain sense to screen the first body against abrupt pressure variations, thus ensuring a more even closing behaviour of the device.
This latter embodiment can have the special feature that the plate defines together with a foremost peripheral edge of the housing an at least more or less flat, annular inlet opening. In this case also a device is realized combining a high degree of effectiveness with a small overall depth.
The spring means can for instance be embodied as at least one usual helical spring. However, a better management and reproducibility is realized with an embodiment wherein the spring means comprise leaf spring means. In a practical embodiment this latter variant has the feature that the leaf spring means are monolithic and comprise a ring connected to the housing and comprising a number of lips supporting the first body. The lips in question can for instance extend substantially radially. In order to realize other spring characteristics the lips can also take other forms, for instance generally spiral shapes and can further have a width varying along their length.
In respect of a good management of the spring characteristic, an embodiment is recommended wherein the leaf spring means consist substantially of stainless steel or spring steel.
The leaf spring means can for instance be manufactured by punching the spring means from sheet material. Punching has the drawback however that the dimensional accuracy can leave something to be desired and that sharp edges can result which may affect the characteristics of the device. In this respect an embodiment is recommended wherein the leaf spring means are manufactured by etching or laser-cutting.
In order to obtain a more readily manageable characteristic and to influence the characteristic such that at low pressure the devices allow a greater flow, a preferred embodiment has the special feature that the first body has at least one continuous hole. Due to the presence of the conti

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