Valves and valve actuation – Rotary valves – Butterfly
Patent
1998-12-18
2000-10-31
Shaver, Kevin
Valves and valve actuation
Rotary valves
Butterfly
F16K 1226
Patent
active
061389889
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a butterfly valve for controlling the flow of a fluid, in particular the air flow rate entering an air distributor provided in a fuel injection device for an internal combustion engine, this valve comprising a housing made of a molded synthetic material in which is arranged a conduit for the fluid to circulate, and a butterfly shutter located at right angles to the conduit and mounted on a control shaft guided in the housing, the shutter being designed to move between a position in which the conduit is closed and the butterfly shutter is oriented substantially perpendicular to said conduit's shaft and a position in which the conduit is fully open and the butterfly shutter is oriented substantially parallel to said conduit's shaft. The invention also relates to the methods for manufacturing this butterfly valve.
BACKGROUND OF THE INVENTION
Butterfly valves are well known and commonly used in the automotive industry. These butterfly valves are usually designed to control the air intake in an air distributor for a fuel injection device using a more or less open butterfly shutter. When the engine idles, this valve has to allow just the right minimum amount of air to pass to ensure that the engines runs. During an acceleration phase, when the driver of a vehicle presses on the accelerator pedal, the butterfly valve has to make it possible to increase the amount of air by instantaneously opening the shutter. In order to ensure flexibility during an acceleration phase, some butterfly valves are designed to allow air to pass through progressively when the butterfly shutter opens. For this purpose, the active inner surface of the valve's housing, i.e. the surface which co-operates with the shutter between its open and closed positions, presents a complex form, provided in particular with a radius of curvature downstream from said shutter in its opening zone.
As a rule, butterfly valves are made of metal and for example of molded aluminum. The housings made in this way generally undergo machining to adjust the internal dimensions according to the shutter. In the case described, for example, in the publication EP-A-109 792 where the housing of the butterfly valve comprises two opposing recesses arranged in the butterfly shutter's opening zones to allow the progressive flow of air when opening. These recesses are achieved by machining, which implies a high cost. Furthermore, for each type of engine, there is a corresponding type of valve with a housing provided with a specific active inner surface according to the variation in the air flow rate required to achieve optimum engine running conditions. It is therefore necessary to provide as many molds for manufacturing housings as types of valves.
It is a well known fact that industrialists are constantly seeking to reduce raw material, manufacturing, assembly and storage costs, as well as reduce the weight of the parts. As a result, some manufacturers have made butterfly valve housings out of molded synthetic material. Two of these embodiments are described in publications FR-A-2 674 573 and FR-A-2 694 963. Nevertheless, the butterfly valves obtained do not make it possible to ensure time-constant air flow rates. Indeed, the material used is generally thermoplastic which is sensitive to variations in humidity and variations in the ambient temperature as well as that of the fluid being conveyed. The result of this is substantial variations in the internal dimensions of the housing, and consequently, the air flow rate for a given position of the shutter. These variations in air flow rate have an effect on the carburation and generate increased pollution from the exhaust gas.
Other butterfly valves are manufactured according to the so-called dual injection process using various materials as described in the publication FR-A-2 687 601 where the body of the valve is molded first, followed by the butterfly shutter. The shutter thus presents absolutely the same form as the body. When operating, there is therefore a risk of the shutter gettin
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Bordellier Franck
Bouvet Thierry
Keasel Eric
M.G.I. Coutier S.A.
Shaver Kevin
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