Fluid handling – Systems – Sequentially progressive opening or closing of plural valves
Reexamination Certificate
1999-12-06
2001-05-22
Michalsky, Gerald A. (Department: 3753)
Fluid handling
Systems
Sequentially progressive opening or closing of plural valves
C123S337000
Reexamination Certificate
active
06234208
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a shut-off device with progressive opening that can be used in particular in a throttle valve to regulate the rate of flow of air to an internal-combustion engine and thus to determined the power it develops, by the movement of a part—typically in the form of a disc—that can pivot about one of its diameters perpendicular to the axis of the pipe in which it is fitted.
In many cases, and in particular in the throttle valve mentioned above, it is important to be able to regulate the rate of flow of a fluid in as progressive a manner as possible, especially at low flow rates. However, in the case of low-viscosity of fluids such as air, most shut-off devices have a virtually “all-or-nothing” action, or at any rate are incapable of precise and progressive regulation of low flow rates.
In addition to a satisfactorily progressive control of flow rate, it is beneficial for such shut-off devices to have at least some measure of adaptability, in order that one device can display different flow characteristics and can thus be used in different contexts (to allow it to be fitted, say, to engines of different horsepower), with the least possible adaptation work. In other words it is desirable that the majority of the components of the device be common to its different applications, and that any parts specific to each of these applications be as few and as inexpensive as possible.
Most known throttle valves are made of metal, for example aluminum, so that the tolerances—and consequently the flow characteristic—are not excessively affected by the large temperature variations to which such a device can be subject, especially in a vehicle, and are also reasonably identical from one specimen to the next. The use of metal is an expensive solution; it would be preferable to find a solution permitting the use of plastic materials, which would also offer a reduction in the weight of the device.
Proposed solutions have already been put forward to solve these problems. For example, document GB 2,254,931 proposes the use of a plastic shut-off member of complicated shape (FIG. 8) comprising in particular a profiled lip (145) to reduce the flow rate when the angle of opening is small. It goes without saying that the production of such a device is complex and demands great precision. This usually means using high-performance—and therefore high-cost—plastic materials, or the use of machining. In addition, the device cannot be adapted easily to different types of engines without machining or replacing the shut-off member. Another problem with the device disclosed in this document is that the profiled lip running all the way around the periphery of the shut-off member, and therefore across the full width of the pipe, creates a significant loss of pressure when the shut-off member is fully open. The device is also characterized by an extremely complicated and bulky bypass idle system.
Another proposal for achieving progressive control of low flow rates involves giving the inside surface of the section of pipe in which the shut-off member is installed an approximately spherical shape so that when the shut-off member pivots open, the distance separating its edge from the wall (and therefore the flow rate of the fluid) initially rises very progressively in a predetermined manner. This proposal, however, makes the pipe section difficult to fabricate, owing among other things to its undercuts. Moreover, the precision with which the inside surface of the pipe must be profiled makes the use of plastic materials inappropriate.
SUMMARY OF THE INVENTION
The present invention seeks to overcome these problems and to provide a shut-off device that is simple to produce, requires no great dimensional accuracy and gives good progressive regulation at low flow rates. When the device is fitted to an internal-combustion engine, more specific objectives relate to easy control of idle (with possible incorporation of a bypass function), and easy adaptation of the device to different use environments. This is useful for, for example, adapting a given engine to allow it to be installed in vehicles with or without an air conditioning system, and/or with or without an automatic gearbox. The invention also seeks to provide a shut-off device, which functions well even if made of plastic. The device of the invention must also have the lowest possible loss of pressure when open.
For this purpose the invention relates to a shut-off device for progressive regulation of the flow rate of a fluid flowing in a pipe, comprising
(a) a main shut-off member able to pivot independently about a spindle passing through the pipe and close the latter, and
(b) at least one drive flap able to pivot about the spindle and act mechanically on the main shut-off member in such a way as to turn it about the spindle; the main shut-off member also being traversed by at least one orifice that can be closed by at least one shut-off flap, which flap can also pivot about the spindle, is integral with the drive flap and can regulate the rate of flow of the fluid through the orifice; the main shut-off member only beginning to pivot about the spindle, from an initial closed position, when the drive flap is at a predetermined non-zero angular distance &phgr; from the member, thus allowing the fluid to flow only through the orifice until the main shut-off member begins to open.
This device fulfils the objectives described above.
The pipe may be of any shape. It is advantageously of a circular section to reduce the perimeter of the main shut-off member and hence the risk of leakage in the closed position.
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Magdelyns Michel
Perez Rufino
Michalsky Gerald A.
Schneller Marina V.
Solvay ( Societe Anonyme)
Venable
Voorhees Catherine M.
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