WO1999046505A1

WO1999046505A1 - Refrigeration compressor with improved stator support

Info

Publication number: WO1999046505A1
Application number: PCT/EP1999/000813
Authority: WO
Inventors: Emilio Pierobon; Enrico Del Fabbro
Original assignee: Zanussi Elettromeccanica S.P.A.
Priority date: 1998-03-10
Filing date: 1999-02-08
Publication date: 1999-09-16
Also published as: IT245300Y1; ITPN980015U1; ITPN980015V0

Abstract

Electric compressor comprising a stator formed by a number of laminations, a plurality of elastic support means, a plurality of contiguous laminations arranged in the lower portion of the stator, said lower portion being formed so that said laminations exhibit a plurality of similar outward oriented appendices, wherein each such appendix is provided with a respective perforation which, together with respective coaxial perforations provided in appendices of said lower portions, forms a channel accommodating engagement means that secure said appendices to the respective support elements. In a preferred manner, said engagement means are rivets passing through said perforations and are locked, at their upper portion, by heading them down onto the top lamination. The elastic support means comprise a helical or cylindric spring and said engagement means are attached thereto by means of heading them onto the upper coil of said helical spring.

Description

REFRIGERATION COMPRESSOR WITH IMPROVED STATOR SUPPORT

DESCRIPTION

The present invention refers to a particular construction of a hermetic refrigeration compressor, m particular such a compressor as used in refhgerahon appliances foi household applications, and namely to the method in which the stator of the electric motor driving said compressor is supported on the lower bottom of the outer casing or shell of said hermetic compressor

To the purpose of more effectively exemplifying the present invention, the assumption is made according to which said outer casing is made of metal, and preferably of deep-drawn sheet-metal, while it will be appreciated that this by no means shall be intended to limit the scope of the present invention to just said kind of mateπal and said kind of connection

Compressoi outei casings are known m the art to be provided with an innei body, le the functional part thereof, which is substantially formed by an electric motor provided with a stator and a I elated rotor, the assembly foimed by the cyhndei and the suction/compression piston, as well as the various associated and auxiliary elements and members

Said inner body of the compressor rests inside the outer casing thereof by means of a plurality of elastic support means More precisely, the whole inner body of the compiessor is integral or is somehow joined with the stator of said electric motor, said stator being in turn supported on the bottom of the outer casing in a any of a variety of methods. One among the most largely used methods relies on the use of following construction: on the bottom of the outer casing there are provided a plurality of resting or supporting means, which are usually formed by cylindrical or helical springs, which rise for a short distance above said bottom.

Between the upper portions of contiguous pairs of said elastic support means there are provided, and duly retained, horizontally extending elements, typically formed by narrow metal stnps, which thereby form a bridge beteen said support means. All such bndges are therefore lifted from the bottom and elasticaily movable since they are supported by said elastic support means.

The stator stack is largely known to be held together by a plurality of screws passing through appropriate channels provided m the laminations of said stator stack, said through-screws, at their respective end po.rtio.ris facing the bottom of the outer casing, being fastened with per se known means to said stnps so that the stator, and therefore the whole inner body of the compressor, is actually enabled to rest elasticaily on the bottom of the outer casing

For a number of leasons, which are largely known to all those skilled in the art so that they do not actually need to be explained any further here, said support means are arranged in positions that are as close as possible to the vertical walls of the outer casing and, therefoie, as far as possible from each other

On the other hand, the dimensions of the stator stack are precisely defined by a number of both mech-anical and electrical constraints, while it is also a largely known, obvious piactice foi said stator stack to be made as compact as possible.

It therefore ensues that the downward egression points of said screws retaining and holding together the stator stack are arranged inside the penmeter that is defined by the plurality of the above cited stnps. For a connection of the stems to said stnps to be enabled, the latter are provided with protrusions or projections extending inwards, so as to intercept and lock the screws of the stator Such a construction, le the presence of said stnps between the support means and, furthermore, the appropriate manner m which said stnps are shaped in order to enable them to be connected with the screws of the stator, implies overall manufactunng costs that are considered to be by all means too high in view of the function being performed by said construction which, it should be once again stressed, has actually to perform just a simple support task.

It would therefore be desirable, and it actually is a main purpose of the present invention to provide a compressor in which sad charactenstics pf elastic supension of the inner body thereof are anyway assured, but at a significantly reduced cost, with the use of readily available, state-of-art matenals and techniques, while at the same time improving the assemblability

The characteristics and features of the present mvention are as recited m the appended claims

The above aims are reached with the technical solutions that will be described below by way of non-limiting example with reference to the accompanying drawings, in which

- Figure 1 is a front plan view of a lamination of a stator stack of a compressor according to the piesent invention,

- Figure 2 is a vertical cross-sectional view of a compiessoi according to the present invention,

- Figure 3 is a schematical perspective view of a stator stack of a compiessor according to the present invention,

- Figure 4 is a view of a detail of a constructive variant of a compressor according to the present invention

-->- The basic idea behind the present mvention can be described as follows- with respect to the support structure of a stator 2 according to the state of the art, the elastic support means 3 are kept in their ongmal position on the bottom 4 of the outer casing of the compressor, while the support stnps joining in pairs said support means to each other, and which are engaged by appropnate through-passing elements performing the double task to holding together the stator stack and securing it firmly to said support stnps, are on the contrary entirely eliminated

As an alternative to the use of said stnps, the lammations of the lower portion 5 of the stator stack are given a shape as substantially shown in particular in Figures 1 and 3, wherem the term lower portion is intended to mean a plurality of contiguous lammations which are arranged toward the bottom of the outer casmg in close proximity of said support means

With particular reference to Figure 1, the laminations illustrated there can be noticed to feature a plurality of axial perforations 1 adapted to accomodate the fastenmg and compacting tie-rods (not shown) that keep the lammations formmg the stator stack appropnately compacted and tight

The lamination illustrated in The Figure is further provided with some protrusions or appendices 6 that are m turn provided with respective through-holes 7

As bettei illustrated m Figure 3, the stator stack can be noticed to be formed by two portions or pluralities of lammations the upper portion 11 is constituted by unmodified lammations of the same stator stack, the lower portion 5 is constituted by substantially identical lammations as illustrated symbolically m Figure 1 , le provided in all cases with at least an appendix 6 that protrudes outwards on the same plane as the lespective lamination

Said laminations of said lower portion are provided with a plurality of perforations 1 coπesponding to the analogous perforations provided m the upper

-4- portion for the passage therethrough of the tie-rods 13 provided for fastenmg and holding together the entire lamination stack, furthermore, the appendix 6 is provided with a respective perforation 7 situated m the same position m each mutually corresponding appendix, so that said plurality of perforations 7 of the appendices are able to form a channel passmg vertically through said appendices

The assembly of the stator stack takes place m the following manner the lammations that are without appendices, and are identical to the lammations of the corresponding pnor-art stator stack, are stacked to form the upper portion The lower portion 5 of the stator stack according to the present invention is on the contrary formed only by lammations of the type illustrated m Figure 1

The stator stack is then locked by means of a plurality of tie-rods 13, which pass through said axial perforations 21 that are common to both types of laminations used and thereby fasten and complete the stator stack

The stator stack is then mounted on said elastic support means 3, wherein the geometry, le configuration, and the dimensions of the thereby involved elements are such as to ensure that the channel formed by said perforations 7 of the appendices comes to lie exactly above the resting area of said elastic support means 3 By means of engagement means 9 it is therefore possible for the lower portion 5 of the stator stack to be secured to said elastic support means and owing to said stator stack being already so formed and consolidated, the whole stator stack is automatically locked m place on to said elastic support means and, therefore, to the bottom 4 of the outer casmg of the compressor, as this is best shown m Figure 2

The present invention also enables further vanants and improvements to be implemented For instance a first variant resides in the fact that the lammations of the lower portion 5 may be provided with a smgle appendix 6 in the case that this is considered appiopπate m view of an adequate reduction in costs, the other parts of the stator being therefore applied on to the bottom of the outer casmg of the compressor accoiding to the tiaditional, le prior-art means and methods

-5- It may on the other hand also prove advantageous, depending on the particular targets or options of the design engineer and the various technical and economic constramts, for a part or the totality of said elastic support means to be fiπnly associated to corresponding channels obtained by stacking, le. superposing on each other, the perforations 7 provided in said lower portion 5 of the stator stack

A second vanant may reside m the fact that said engagement elements 3 are constituted by nvets that are headed on both ends thereof, le. against the upper lammation 10 of said lower portion and, on the other side, against an appropnately provided undercut m the respectiveresting means 3

In an advantageous manner, where the elastic means of said elastic support means 3 is constituted by a cyl dnc or helical spring, said undercut is formed by the last coil of said sprmg

Such a circumstance would offer the advantage of significantly simplifying the overall construction owing to it enabling any further connection means, except for said nvet, to be prevented from being needed and used between spring and stator stack

Furthermore, m view of making the construction of said stator stack more easily and efficiently processable, the lammations of said lower portion 5 of the stator stack may be processed m such a manner as to ensure that the respective appendices 6 and the related perforations 7 are, m each lammation, in the number of four and are positioned diagonally and/or symmetrically with respect to either the ajαs O of the stator or a vertical plane "A" crossmg said axis

A further vanant, which is illustrated m Figure 4, refers to the manner m which said engagement means 9 are fastened to the respective elastic support means

In this vanant, said engagement means 9 is constituted by a rivet that is headed on both sides of the lower portion 5 of laminations, the lower heading 22 is much larger than actually needed to ensure the firmness of the nvet and, in particular, its

-6- width is such as to enable it to be perfectly enveloped, practically with no slack or play at all, by the upper coils 10 of the helical sprmg 3, while its depth extends to reach at least the level of the second or successive coil 24

In this manner, a safe, simple and veiy easily assemblable securing arrangement is obtained.

It will be appreciated that the descnption and illustrations set forth above with reference to the accompanying drawmgs have been given merely by way of non-limiting example of possible embodiments of the present mvention, and that a number of further variants and modifications may therefore be developed without departing from the scope of the present mvention

-7-

Claims

1. Electric compressor, in particular for household refrigeration appliances, compnsing an outer casmg (1), a stator (2) formed by a plurality of stacked ferromagnetic laminations, a plurality of elastic support means (3) for the stator to rest on the bottom (4) of said outer casmg, charactenzed m that a plurality of contiguous laminations arranged m the lower portion (5) of the stator are formed so that said laminations exhibit a plurality of similar, outward onented appendices (6), wherein each sue appendix is provided with a respective perforation (7) which, together with corresponding coaxial perforations provided in appendices of said lowei portion, forms a channel adapted to accomodate respective engagement means (9) securing said appendices to the respective support means (3)

2. Compiessor according to claim 1, characterized m that said engagement means (9) are nvets passing through said perforations (7) and retamed, at their upper end, by them being headed on to the upper lamination (10) of said plurality of lammations mcluded m said lower portion (5)

3. Compiessoi according to claim 2, characterized m that at least some of the elastic support means (3) comprise a helical or cylindnc spnng, and that said engagement means (9) are retamed by them being headed on to the upper coil of said helical or cylindnc spring

4. Compressor according to claim 3, charactenzed m that said engagement means (9) are constituted by nvets that are headed on both sides of said lower portion (5) of laminations, said nvets bemg provided with a lower heading (22) having such a width as to be capable of bemg tightly enveloped, le. practically without any slack or play, by the upper coils (10) of said helical spnng (3), and having further such a depth as to be able to reach at least to the level of the second coil or successive coil (24).

5. Compressor according to any of the preceding claims, charactenzed in that said stator rests on the bottom of the outer casmg solely through said elastic support means (3), any further intermediate support means bemg excluded.

6. Compressor according to any of the preceding claims, charactenzed in that said perforations (7) are provided m the number of four m each lammation and are arranged m pairs either diagonally with respect to the axis O of the stator or symmetncally with respect to a vertical plane (A) crossmg said axis.