FR2660973A1 - CYLINDER HEAD GASKET OF AN ALTERNATIVE COMPRESSOR. - Google Patents

Abstract

Cylinder head gasket of a reciprocating compressor, comprising a cylinder block (1) comprising a cylindrical cavity housing a reciprocating piston (2) and one end of which is open on an end face of the block; a valve plate (3) with a front face and a rear face being fixed against said end face of the cylinder block (1) and supporting a suction valve (3a) and a relief valve (3b); a cylinder seal between said rear face of the valve plate and said end face of the cylinder block; a cylinder cover (5) internally forming a suction chamber (5a) and a discharge chamber (5b) which are open on an end face of the cylinder cover formed by an edge surrounding said suction chamber (5a) ) and said discharge chamber (5b) and being fixed against the front face of the valve plate (3); and a cylinder head gasket (10) disposed so as to compress between the cylinder cover (5) and the valve plate (3). According to the present invention, a portion of the cylinder head gasket (10) projects onto the internal part of the cylinder cover (5) from the surrounding edge, at least in its portions which surround the discharge chamber (5b) and are more likely to slip or break, said seal portion being, in the chamber, of a thickness which is greater than the thickness of the seal portion being compressed between said surrounding edge and said valve plate (3 ).

Description

CYLINDER HEAD GASKET OF AN ALTERNATIVE COMPRESSOR

  The present invention relates, in general, to

  reciprocating compressors for small refrigerated appliances

  rants and, more particularly, a new construction

  applied to the cylinder cover gasket of a compressor

  hermetic reciprocating piston. In compressors with a reciprocating piston, the

  cylinder head normally supports a valve plate with

  both within it the suction and discharge valves, a cylinder head which is normally cast or molded, a cylinder head gasket disposed between the valve plate and the cylinder block, and a cylinder cover gasket, disposed between the cylinder cover cylinder and the valve plate, these seals being intended to prevent leaks from the discharge chamber to the suction chamber, from the discharge head

  from the compressor and the cylinder to the inside of the

Velcro enclosing the whole -

  The cylinder cover and the valve plate

  are generally rectangular in shape and are fixed in-

  seems to the cylinder block by means of bolts, generally four, which are arranged near the corners of the cover and the

valve tray.

  Due to a malfunction of the compressor, the

  pressure in the discharge chamber formed within the

  cylinder circle can increase sharply and very strongly

  These increases in pressure in the discharge chamber can occur for various reasons, for example due to the compression of liquid (condensed coolant) in the cylinder or a restriction (obstruction)

  of the compressor discharge flow after the discharge chamber

  charge, in the acoustic filters or in the discharge tube

  load These failures are not uncommon and the compress-

  sor, in particular the hermetic compressor, must be

  built to withstand these pressure increases.

  In certain situations, the increase in pressure in the discharge chamber may be sufficient to cause the cylinder cover seal to slip and even break. In both cases, the seal is irreparably damaged.

  So far, the solutions used to minimize

  reduce the risk of displacement or rupture of the seal

  vercle can be summarized as follows: One of the solutions of the prior art consists in forcing

  the bolts to fix the cover-base plate assembly

  popes to the cylinder block This solution is not reliable because it can easily cause warping of the

  cylinder cover, or produce undesirable deformations

  the fixing elements, i.e. the plugs

  uons and the threads in the cylinder.

  In another known solution, it is proposed to

  increase the surface roughness of the edges of the cover

  cylinder on which the edge portion of the seal

cylinder ring rests.

  Although this solution increases the resistance of the seal to pressure increases in the discharge chamber, it requires an expensive operation and a difficult maintenance of the casting mold or molding, necessitating reworking.

  constant condition due to wear and tear in the pro-

  yielded by manufacturing This increase in surface roughness can also be obtained by post-machining, although

  that this represents an increase in the manufacturing cost.

  In another solution of the prior art, described

  in German patent NI DE 3534289 AI, ribs or nerves

  vures are formed on the side edges of the cylinder cover, to serve as retaining stops for the gasket

  cylinder cover This solution is not reliable because of

  which only prevents the seal from sliding on its

  external riphery, but does not avoid internal sliding,

  the surface of the cylinder cover gasket resting

  be the wall that separates the suction and discharge chambers

  load, or externally, to the play existing between the rib

  and the end of the valve plate.

  The object of the present invention is to provide a

  cylinder head gasket, more particularly a cover gasket

  cylinder key, for reciprocating compressors, said

  gasket being of simple construction and easy to counter

  1st, without cost increase implied by the solutions

  known, and also very reliable.

  The cylinder head gasket, which is the subject of this

  invention, is applied to a hermetic compressor alter-

  native comprising: a cylinder block comprising an extremi-

  open tee and housing a reciprocating piston; a

  valve plate one of the faces of which is fixed to the ex-

  open end of the cylinder block and supporting suction and discharge valves; a cylinder seal disposed between said cylinder block and said valve plate; a

  cylinder cover internally defining a chamber

  suction bre and a discharge chamber and comprising an open rear face defined by a surrounding edge

  said suction and discharge chambers and being closed

  xed against the other side of the valve plate; and a cylinder cover gasket between said cover and said

valve tray.

  According to the present invention, a portion of the seal of

  cylinder cover extends to the inside of the cover

  cylinder ring, from the rear surround edge, at least in its portion surrounding the discharge chamber and having a greater extension, said seal portion being, within the chamber, of greater

  thickness that the joint portion being compressed between the-

  says surround edge and valve tray.

  The joint generally has a uniform thickness

  before being assembled In this case, it's unique-

  tightening the fastening means of the cover and the

  valve plate to the cylinder block which causes a diff-

  thickness difference between a compressed joint portion and an uncompressed joint portion which projects up to

  inside the surrounded room.

  However, it is understood that the seal portion, which extends to the interior of the surrounded chamber and which is not compressed during assembly of the assembly on the cylinder block, is slightly thicker than the width

  remaining of the joint, this difference in thickness being increased

  lying during normal compression of the joint when

the assembly is assembled.

  The present invention allows the formation of a shoulder-

  generally continuous in the own body of the joint, along its border overlooking the interior of the chamber

  surrounded by said joint portion, said shoulder serves

  front of stop together with the internal face of the leading edge

  turning the cover, preventing the seal from sliding towards

  the outside from said cover or break.

  The width of said portion of joint is greater

  that the width of the surrounding edge of the cylinder cover

  dre, so that part of its width occupies the entire width

  geur of the surrounding edge of the cover and is compressed by it, and that part also of the remaining uncompressed width is projected into the interior of the

room surrounded.

  The present invention will now be described with reference to the accompanying drawings, in which: FIG. 1 is a view in longitudinal section of the cylinder head of an alternative hermetic compressor; Figure 2 is a plan view of the rear face of the cover, taken along line II-II of Figure 1; Figure 3 is a plan view of the cylinder cover gasket;

  FIG. 4 schematically illustrates, in section through

  tial and on a larger scale, the relative positioning

  between a portion of cover gasket and the edge of the surround

  rage of the discharge chamber of the cylinder cover, before compression of the seal; and Figure 5 is a view similar to Figure 4, but illustrating the assembly after the compression of the seal.

  As shown in Figure 1, the present invention

  tion is used in an alternative compressor comprising

  a cylinder block 1 disposed within an envelope (not

  presented) in the case of hermetic and com- pressors

  bearing a cylindrical cavity with a reciprocating piston 2

moving there.

  The cylinder block 1 has one end of its cavity, nor-

  the front end, open to receive a plate,

  valve cover 3, one of the two opposite faces of which is wedged against the front end face of the cylinder block 1

  and wedged against it by means of a cylinder seal 4.

  The valve plate 3 is axially perforated so that

  to accommodate a 3 a suction valve and a de-

  charge 3 b which are in fluid communication with the interior

  laughter of the internal cavity or compression chamber of the

cylinder block 1.

  Against the front face of the valve plate 3, opposite

  placed on the cylinder block 1, is fitted a cylinder cover, made of cast iron or cast aluminum and of a shape such that it internally defines a suction chamber a in fluid communication with the suction valve

  3 a, and a discharge chamber 5 b in fluid communication

  of with the relief valve 3 b, these chambers being or

  green towards the rear face of the cover which is wedged

be the valve plate.

  The cylinder cover 5 has its rear face, to be wedged against the valve plate 3, formed only by a

  flat edge 5 c (see figure 2) with a reduced width relatively

  the peripheral dimensions of the cover and surrounding

  between the suction chamber 5 a and the discharge chamber b This known construction means that the support plate

  popes 3 forms the flat rear wall of the vacuum chamber

  ration 5 a and the discharge chamber 5 b.

  To guarantee the tightness of the suction and discharge chambers 5 a and 5 b, a cylinder head gasket 10 is arranged

  between the rear edge of the surround 5 c of the cy-

  lindre 5 and the adjacent front face of the valve plate 3. The fixing of the cylinder cover 5 and of the valve plate 3 to the cylinder block 1 is carried out by means of screws (not shown) passing through the corresponding axial holes 5 d and 13 formed in the cover 5 and the cylinder head gasket 10, respectively, and being screwed into openings provided in the cylinder block 1, after a

  passage through corresponding axial holes (not shown

  formed in the plate 3 and the cylinder gasket 4. The cylinder head gasket 10 is of sufficient thickness

  to guarantee, after compression and deformation,

  raised by tightening said screws to fix the cover

  cylinder, adequate sealing of the vacuum chamber

  ration 5 a and of the discharge chamber 5 b This seal of cu-

  lasse 10 can be made of any suitable material

  property such as, for example, hydraulic cardboard with asbestos or asbestos or cotton fibers connected with rubber is provided with an opening 14, corresponding to the discharge chamber 5 b and with an orifice 15 corresponding

  when opening the suction valve on the support plate

popes 3.

  The cylinder head gasket 10 made of hydraulic cardboard with

  rubber is of a thickness normally comprised between-

be 0.3 mm and 0.5 mm.

  As shown in Figures 3, 4 and 5, the solution

  tion which is the object of the present invention to provide a cylinder head gasket 10 to the dimensions, in terms of outline and width, to form a portion of seal 11 projecting into the interior of the cylinder cover 5 , from the rear edge of surround 5 c, at

  less in its portions which surround the discharge chamber

  age 5 b and the tightening force of the seal against the neck

  cylinder ring or the valve plate is less. In the illustrated embodiment, the entire cylinder head gasket 10 has the same initial thickness "E", before being compressed between the cylinder cover 5 and the valve plate 3 In this configuration, all the portions of the gasket cylinder head 10 surrounding the discharge chamber 5 b (see FIG. 3) are of greater width

  to the width necessary to cover the corresponding portion

  edge of the rear surround edge, in order to form the

  tion 11 projecting inwards above along the entire periphery of the seal between the discharge chamber b and the valve plate 3. It is understood that the increase in width of the cylinder head gasket can only be achieved in the portions of the rear surround 5 c that are most likely to

to break up.

  In the embodiment illustrated in the drawings,

  before tightening the cylinder cover fixing screws

  dre 5, the cylinder head gasket 10 has the same thickness "E" over its entire length, including said portion 11 which projects towards the inside of the discharge chamber 5 b

(see figure 4).

  When tightening the fixing screws, the portion of the cylinder head gasket 10 between the rear surround 5c and the valve plate is compressed, then being of a thickness "e" less than the initial thickness' E " , who

  is kept in portion 11 projecting inwardly

  of the cylinder head gasket (see Figure 5).

  Thanks to the aforementioned difference in thickness, the portion 11 projecting inwardly of the cylinder head gasket forms

  a shoulder 12 near the internal edge of the adjacent portion

  center of the rear edge of surround 5 c, which prevents the

  head gasket 10 to slide away from the mounting surface

  between the valve plate 3 and the cylinder cover

lindre 5.

  To form a shoulder 12, adapted to retain ma-

  sure the joint under conditions of high pressure, it is preferable to use a portion Il in projection

  inward about 1.2 times the width

  edge of the cylinder cover.

Claims (2)

  1 Cylinder head gasket of a reciprocating compressor,   nant a cylinder block (1) comprising a cylindrical cavity housing a reciprocating piston (2) and one end of which is open on an end face of the block; a valve plate (3) with a front face and a rear face being fixed against said end face of the cylinder block (1) and supporting a suction valve (3 a) and a pressure valve   discharge (3 b); a cylinder seal between said rear face   valve tray and said end face of the   cylinder block; a cylinder cover (5) forming an interior   a suction chamber (5 a) and a discharge chamber (5 b) which are open on one end face of the   cylinder cover formed by an edge (5 c) surrounding the   said suction chamber (5 a) and said discharge chamber   ge (5 b) and being fixed against the front face of the   valves (3); and a cylinder head gasket (10) arranged in a manner   re to compress between the cylinder cover (5) and the valve plate (3), characterized in that a portion   (11) of the cylinder head gasket (10) is projected onto the part   inner tie of the cylinder cover (5) from the surround edge (5 c), at least in its portions which surround   the discharge chamber (5b) and are more likely to slip   tighten or break, said seal portion (11) being, in the chamber, of a thickness (E) which is greater than   the thickness (e) of the joint portion being compressed in   be said surround edge (5 c) and said valve plate pes (3).   2 cylinder head gasket according to claim 1, charac-   in that it has the same thickness (E) over its entire length before being compressed between the valve plate (3) and the surround edge (5 c) of the cylinder cover (5).