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  Device for producing high pressure in a fluid in miniatureUSPTO Application #: 20060285987Title: Device for producing high pressure in a fluid in miniature Abstract: A miniaturized device for pressurizing fluid. The device includes a hollow piston that provides a fluid path and a valve member. The valve member is configured for axial movement so that the valve axis remains parallel to the piston axis. The valve member is arranged at one end of the hollow piston. The valve member may be partially or completely disposed within the hollow piston. The device is particularly adapted for use in a mechanically operated atomizer to produce an inhalable aerosol of a liquid medicament without the use of propellant gas. (end of abstract)
Agent: Sterne, Kessler, Goldstein & Fox PLLC - Washington, DC, US Inventors: Joachim Jaeger, Pasquale Cirillo, Joachim Eicher, Johannes Geser, Bernhard Freund, Bernd Zierenberg USPTO Applicaton #: 20060285987 - Class: 417572000 (USPTO) Related Patent Categories: Pumps, Miscellaneous The Patent Description & Claims data below is from USPTO Patent Application 20060285987. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present application is a continuation of U.S. application Ser. No. 11/165,496, filed Jun. 24, 2005; which is a continuation of U.S. application Ser. No. 10/807,447, filed Mar. 24, 2004, now U.S. Pat. No. 6,918,547; which is a continuation of U.S. application Ser. No. 10/292,470, filed Nov. 13, 2002, now U.S. Pat. No. 6,726,124; which is a continuation of U.S. application Ser. No. 10/143,006, filed May 13, 2002, now U.S. Pat. No. 6,497,373; which is a continuation of U.S. application Ser. No. 09/354,663, filed Jul. 16, 1999, now U.S. Pat. No. 6,402,055; which is a division of U.S. application Ser. No. 08/726,219, filed Oct. 4, 1996, now U.S. Pat. No. 5,964,416. The disclosures of the above-referenced applications are incorporated by reference herein in their entirety. BACKGROUND OF THE INVENTION [0002] The invention relates to a device for producing high pressure in a fluid. It comprises a piston which is movable in a cylinder, and a valve, both preferably of miniaturised construction. The invention further relates to a high pressure atomiser which contains this device, and the use thereof, preferably for medicinal purposes. [0003] One aim of the invention is to enable a device of this kind and the atomiser containing the device to be made simpler in design and cheaper to produce and suited to its function. [0004] In liquid chromatography (HPLC), for example, generally relatively small quantities of liquid are conveyed at high pressure through the separating column. Moreover, in medicinal aerosol therapy, aerosols are obtained, by atomising or nebulising liquid drugs for treating diseases of the respiratory tract in humans or for treating asthmatic conditions. Here again, a high pressure is required in a, generally relatively small, quantity of fluid in order to produce the small droplet size needed for the aerosol. In the metered dose inhaler according to U.S. Pat. No. 5,497,944, (the entire contents of which are incorporated herein by reference) a predetermined volume of a fluid is sprayed through a nozzle with a small aperture under a pressure of between 5 and 40 MPa (about 50 to 400 bar) to produce an aerosol. The present invention is particularly applicable to such metered dose inhalers and similar devices. BRIEF SUMMARY OF THE INVENTION [0005] According to one aspect of the invention there is provided a device, preferably of miniaturised construction, for producing high pressure in a fluid, comprising a piston which is movable in a cylinder, a high pressure chamber which is located in front of the piston inside the cylinder, and a valve, which device includes [0006] a cylindrical hollow piston, [0007] a valve member which is guided by the hollow piston and is mounted so as to be axially movable against the hollow piston, [0008] a stop means on the hollow piston which holds the valve member to the hollow piston and [0009] a defined (predetermined) sealing surface at the inlet end of the valve member, the valve member generally being restrained from rotation about any axis transverse to the piston axis. [0010] According to another aspect of the invention, there is provided a device for producing high pressure in a fluid, preferably of miniaturised construction, comprising a cylinder, a hollow cylindrical piston which is movable in the cylinder and provides a path for fluid therethrough, a high pressure chamber which is located in front of the piston inside the cylinder and which is supplied with fluid through said path, and an inlet valve in said fluid path which moves with the piston but is also capable of limited guided movement along the piston axis between a closed position in contact with a valve seat provided by the piston and an open position spaced from the valve seat, the valve member being so shaped and guided that it cannot rotate about any axis transverse to the piston axis such that a predetermined surface thereof engages the seat. [0011] In U.S. Pat. No. 5,497,944, there is described and shown a similar device in which the check valve member is a ball. With such an arrangement, the ball can rotate during multiple operations. It has been found that wear and distortion under the high pressure involved can permanently deform the ball so that if a different part of its surface is used during sequential closing and sealing operations (because the ball is free to rotate about a transverse axis) there is a tendency for leakage to occur. This can be avoided by using the same surface of the valve member each time thus allowing bedding down to ensure the desired seal. In the preferred arrangement according to the invention, at least a major part of the valve member is cylindrical and is guided in a chamber (which may, for example, be the pump chamber itself or may be part of the interior of the piston) and the valve member cylinder has an end surface which co-operates with the valve seal provided by the piston. Another disadvantage of a ball valve which can be avoided using the invention is that the transverse area of the valve is necessarily considerably smaller than the diameter of the ball and thus the guide cylinder in which it moves; this leads to a reduction in the force applied by the valve member to the valve seat arising from fluid pressure generated during the pressure stroke (forward movement) of the piston. A high application force of the valve member is desirable to slightly elastically deform the valve member and/or the valve seat to close any slight gaps between them. [0012] In the specification which follows, the terms inlet and outlet side or inlet and outlet end are used in relation to the main direction of flow of the fluid within the device. The term fluid includes both gases and liquids but the present invention is mainly concerned with liquids. [0013] The valve member is somewhat displaceable against the hollow piston but it moves substantially with the hollow piston. [0014] The valve member is preferably uniaxially rotationally symmetrical in shape, e.g. it is a circular cylinder or a frustum. Its cross-section is somewhat smaller than the cross-section of the chamber in which the valve member is movably mounted. This is achieved by means of one or more channels preferably extending in the outer surface of the cylindrical valve member, or by a somewhat smaller diameter of the valve member in relation to the diameter of the chamber in which the valve member is movably mounted. [0015] The valve member is guided in the chamber in which it is movably mounted; a cylindrical valve member can rotate about its axis as required, but its axis always remains parallel to the axis of the hollow piston. This produces a defined sealing surface at the inlet end of the valve member. [0016] The distance over which the valve member can travel relative to the hollow piston is limited by a stop or stop means which holds the movable valve member together with the hollow piston. [0017] In some embodiments of the invention wherein the stop is beyond the outlet end of the valve member, there may need to be at least one recess in the region of the outlet end of the valve member to enable the fluid to flow through between the stop and the valve member when the valve is open. Each recess is located either in the valve member at the outlet end thereof or in the stop in the hollow piston. [0018] In the position where the valve member abuts on the stop of the hollow piston, the valve is opened. In the position where the valve member abuts on the defined sealing surface, the valve is closed. [0019] A valve member arranged inside the hollow piston has virtually no friction against the inner wall of the hollow piston. A valve member arranged directly in front of the end of the hollow piston may possibly rub against the wall of the main pump cylinder of the device. In this case, the valve is actively closed and opened as the hollow piston moves, on account of the friction between the valve member and the cylinder wall. [0020] The cylinder preferably consists of plastics and the hollow piston of metal or plastics. The material for the valve member is selected, in terms of its hardness, to complement the hardness of the material for the hollow piston and may be metal, ceramics, glass, gemstone, plastics or elastomer. The valve member is preferably manufactured in one piece. [0021] When the fluid is sucked in, the high pressure chamber is connected to the fluid supply by means of the hollow piston. During the intake stroke of the hollow piston the fluid flows through the hollow piston and past the valve member into the high pressure chamber of the cylinder. During the exhaust stroke of the hollow piston the valve seat is sealed in a high pressure tight manner against the defined sealing surface of the valve member. Continue reading... Full patent description for Device for producing high pressure in a fluid in miniature Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Device for producing high pressure in a fluid in miniature patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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