Pipes and tubular conduits – With pressure compensators – Variable capacity chambers
Patent
1999-06-29
2000-12-26
Hook, James
Pipes and tubular conduits
With pressure compensators
Variable capacity chambers
138 26, 303 87, F16L 5504
Patent
active
06164336&
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a hydraulic capacity, for example one which can be used as a variable-pressure accumulator in a braking circuit.
More specifically, the present invention relates to a hydraulic capacity comprising a hollow body which is elongate along an axis, and a rigid casing, the hollow body being made of a material that can withstand elastic expansion from a state of rest, at least in a radial direction with respect to the axis, the hollow body being defined, at rest, by a wall the thickness of which is between a minimum thickness and a maximum thickness, this wall being bordered by an orifice which is stationary with respect to the rigid casing, the rigid casing surrounding the hollow body in order to limit its expansion, and this capacity being intended to contain, at every instant, an instantaneous volume of fluid which can change between a minimum volume and a maximum volume, this capacity applying to the instantaneous volume of fluid an instantaneous pressure that depends on the instantaneous volume.
A hydraulic capacity of this type is known and for example described and illustrated in patent document WO 98/00320.
BACKGROUND OF THE INVENTION
In actual fact, this patent document forms part of a far wider prior art which also contains, in particular, patents U.S. Pat. Nos. 3,948,288 or 5,718,488 and which aims to produce a pressure-fluctuation damper.
The invention falls within a very different context and aims to produce a capacity that can be used as a hydraulic accumulator capable of applying to the fluid it contains a pressure that is connected, through a predetermined relationship, to the volume of fluid accumulated, it being possible for such an accumulator to act as a brake-actuation simulator, of the type described, for example, in patent documents FR-2,753,949 and FR-2,756,797.
SUMMARY OF THE INVENTION
To this end, the hydraulic capacity of the invention, which in other respects is in accordance with the definition given in the above preamble, is essentially characterized in that the wall of the hollow body, at least for a first instantaneous volume of fluid, is simultaneously in contact with the casing at least via a first zone and a second zone of this wall, which zones are distant from the orifice, having first and second respective thicknesses and separated from each other by a third zone distant from the casing and having a third thickness different from the first and second thicknesses.
In order to follow with optimum precision the predetermined relationship that is supposed to connect the pressure of the stored fluid to the volume of the latter, it may be beneficial for the first and second thicknesses to be given different values from each other.
In one possible embodiment of the invention, the hollow body has an internal surface which is essentially cylindrical at rest.
The wall may furthermore achieve its minimum thickness at one end of the hollow body, this being the opposite end to the orifice, and at this end may have an external surface which, at rest, lies inside a cylinder of a first diameter.
In this case, it is possible to envisage that the casing, opposite the end of the hollow body, should form a cylinder of a second diameter, greater than the first diameter.
Finally, the wall may achieve its maximum thickness at a number of intermediate zones lying axially between the orifice and the end of the hollow body, and in which zones the wall has an external surface which, at rest, lies inside a cylinder of a third diameter, greater than the second diameter.
Other features and advantages of the invention will emerge clearly from the description thereof given hereafter by way of non-limiting indication, with reference to the appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view of a capacity in accordance with the invention; and
FIG. 2 is a diagram illustrating a relationship between the change in pressure of a fluid stored in the capacity of FIG. 1 and the volume of this fluid.
DETAILED DESCRIPTION OF THE INVENTION
The inv
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patent: 4687188 (1987-08-01), Knurek et al.
patent: 5682923 (1997-11-01), Goloff et al.
patent: 5803555 (1998-09-01), Schaefer
patent: 6056013 (2000-05-01), Sasaki et al.
patent: 6076557 (2000-06-01), Carney
Delage Jean-Pierre
Fourcade Jean
Pasquet Thierry
Bosch Systemes de Freinage
Comstock Warren
Hook James
McCormick Jr. Leo H.
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