JP2010513786A - Annular regenerator assembly - Google Patents

Abstract

An annular regenerator assembly comprising an annular regenerator medium (1) whose inner and outer surfaces are bounded by an inner sleeve (2) and an outer sleeve (3), respectively. At least one of the sleeves has a bend (4) for forming an annular seal projection extending around the sleeve and projecting away from the regenerator medium.
[Selection] Figure 1

Description

  The present invention relates to an annular regenerator assembly.

  Annular regenerator assemblies have been designed for Stirling machines, more specifically linear free piston Stirling engines. However, the regenerator can be used in any situation where an annular regenerator is required.

  Annular regenerators are well known in the field of Stirling engines. Many different regenerator materials may be used and may be broadly classified as wire, foil, gauze, or foam type materials.

  The current method used by the applicant is to pack random wires into the annular regenerator space in the Stirling engine head after the internal acceptor fins are brazed in place. This is a labor intensive process that is not suitable for cost-effective mass production.

  It is well known in the art to have a regenerator assembly whose inner and outer surfaces are bounded by an inner sleeve and an outer sleeve, respectively (e.g., Japanese Patent No. 62-082264, US Pat. No. 6,862,883). Description and US 2006/0118273). These are provided for many reasons, for example to keep the regenerator element in place.

  The inability of the gas flow to bypass the regenerator is very important for efficient engine operation. For this purpose, JP-A-62-082264 provides an O-ring that seals each sleeve together with the cylinder and casing.

  Such a structure has a number of drawbacks. The use of an O-ring means that it is not suitable for use in high temperature applications, increasing the number of components required.

  According to the present invention, an annular regenerator medium is provided whose inner and outer surfaces are bounded by an inner sleeve and an outer sleeve, respectively, at least one of the sleeves extending in a direction away from the regenerator medium. An annular regenerator assembly is provided having a bend forming a protruding annular seal protrusion.

  The present invention provides a simple regenerator structure that is suitable for mass production and can be used in high temperature engines. Also, the present invention does not rely on precise tolerances between the sleeve and the surrounding components that are susceptible to problems associated with thermal expansion differences.

  The regenerator assembly can be manufactured as a single component that can be easily pushed into place in the engine head with an annular seal projection that provides a seal between the engine cylinder and the engine casing.

  In the broadest sense, the sealing protrusion may be provided on only one of the sleeves. In this case, some other sealing mechanism is provided on the other sleeve. However, it is preferred that each annular seal projection be provided on each of the sleeves.

  The present invention also works with a single protrusion on each sleeve. However, it is preferred that the sleeve or each sleeve has two or more annular seal protrusions, each protrusion being formed by a respective bent portion of the sleeve.

  The invention also extends to a method of forming an annular regenerator assembly according to the first aspect of the invention. The method broadly includes combining an inner annular sleeve and an outer annular sleeve, bending at least one of the sleeves to form an annular seal protrusion extending around the sleeve, and a regenerator in the assembly. Filling the medium.

  If the regenerator medium is of the type likely to have a free element, the method includes attaching an end cap that covers the space between the sleeves at one end prior to the filling step, and regenerating after the filling step. Preferably, the method also includes attaching an end cap on the opposite end of the vessel assembly.

  The bending step may be performed before or after the assembly is filled with the regenerator medium.

  The method may also include the step of removing the end cap prior to assembly into the engine.

  An example of a regenerator assembly according to the present invention will now be described with reference to the accompanying drawings.

It is a disassembled perspective view of the regenerator by which a part is shown with a cross section. FIG. 3 is a partial perspective view with a cross section in part showing a regenerator assembly inserted into a Stirling engine.

  The regenerator includes a heat storage material 1 having an annular shape. The heat storage material may be any suitable material such as wire, foil, gauze, or foam. The inner surface of the regenerator material 1 is bounded by an inner cylindrical sleeve 2 and the outer surface is bounded by an outer cylindrical sleeve 3. Each sleeve is provided with a pair of bends 4 spaced from the ends and extending around the sleeve. These bends form a convoluted portion that provides an annular seal lip surrounding the sleeve.

  An upper end cap 5 and a lower end cap 6 are attached over each of the upper and lower ends of the assembly. These end caps have an inner lip 7 and an outer lip 8 to help position the cap on the end of the regenerator assembly.

  To assemble the regenerator assembly, the sleeves 2 and 3 are held together in the lower cap 6. Thereafter, before the upper cap 5 is mounted in place, the regenerator material is packed to a specific density into the annular space formed between the cylinders. The end cap holds the contents of the assembly during transport and also provides structural integrity.

  The bends may be formed prior to assembly, for example by a bulge forming process described in US Pat. No. 6,044,678. Alternatively, these bends may be formed after the regenerator is assembled. In this case, the end cap is removed and the molding process compresses the two sleeves together along most of their length, leaving only a circumferential gap, thereby forming a bend as an uncompressed ring. The As a result, the cylinder is compressed against the internal filling, thereby removing any filling voids remaining after the filling process. If necessary, another set of end caps having dimensions that fit the compressed shape is then attached for transport. If a filling material such as foil is used, an end cap may not be required for shipping.

  The method can be used with random steel wire as a regenerator material. However, the method can also be used with more rigid regenerator materials such as foil, fine wire mesh or foam. One of the advantages of this structure is obtained when it is used with more rigid materials. Of course, these materials do not fill the irregular space forming the regenerator passage in the same way that random wires fill. Thus, regenerators based on these harder materials enjoy the benefits of such a sleeve structure that uses an integral annular seal ring.

  The assembly of the regenerator assembly to the Stirling engine is shown in FIG. FIG. 2 shows a part of the engine head. The engine includes a casing 10 provided with an annular array of acceptor fins 12 at its upper end. The end caps 5 and 6 are removed before being assembled to the engine. Thereafter, the assembly is pushed into the engine head. The annular seal protrusions 4 compress as they fit into the engine, thereby deforming the sleeves 2 and 3 to an acceptable level, resulting in a non-uniform or non-cylindrical surface on which the seal is formed. Even so, a seal is formed (to within manufacturing tolerances).

  In order to prevent the wire particles from spreading into the body of the engine, if the cartridge contains random wires, a sintered ring may be required above and below the cartridge. These sintered rings (with appropriate fastening means, for example with a positioning lip as shown) form a permanently sealed component and avoid the need for further components and mounting operations Can be used instead of the end caps 5 and 6.

  The inner and outer seal protrusions 4 press firmly against the casing 10 and cylinder 11 to form a seal and prevent gas from bypassing the regenerator material during operation. In the illustrated example, the sleeve, casing, and cylinder are all manufactured from stainless steel so that there is no difference in thermal expansion and the seal is maintained at all operating temperatures.

Claims (6)

  An annular seal comprising an annular regenerator medium bounded by an inner sleeve and an outer sleeve, respectively, on an inner surface and an outer surface, wherein at least one of the sleeves extends around the sleeve and projects away from the regenerator medium An annular regenerator assembly having a bend for forming a protrusion.   The annular regenerator assembly according to claim 1, wherein each annular seal protrusion is provided on each of the sleeves.   The annular regenerator assembly according to claim 1 or 2, wherein the sleeve or each sleeve has two or more annular seal protrusions, and each protrusion is formed by a respective bent portion of the sleeve.   A method of assembling an annular regenerator assembly according to any one of claims 1 to 3, comprising combining an inner annular sleeve and an outer annular sleeve, bending at least one of the sleeves, Forming an annular seal projection extending around the periphery of the annular regenerator assembly and filling the annular regenerator assembly with a regenerator medium.   Attaching an end cap that covers the space between the sleeves at one end before the filling step; and attaching an end cap on the opposite end of the annular regenerator assembly after the filling step. The method of claim 1.   The method of claim 5, further comprising removing the end cap prior to assembly in an engine.

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