Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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"VALVE MOUNTING ARRANGEMENT FOR A REFRIGERATION
COMPRESSOR"
Field of the Invention
The present invention refers to an arrangement for
mounting a valve, which is not of the single piece
type, in a refrigeration compressor, such as that used
in small refrigeration systems.
Background of the Invention
The energetic efficiency of the refrigeration
compressors is mostly attributed to the good
performance of their valves in the control of the gas
flow.
In the reciprocating refrigeration compressors, the
compression of the refrigerant gas is achieved by
movement of the piston, which is driven by a driving
means, such as a mechanism of the connecting rod -
crankshaft type, or by a linear motor. The piston
reciprocates inside the compression chamber and, at
the moment it begins to return from the upper dead
point to the lower dead point, in its suction stroke,
it draws the refrigerant gas from the suction line of
the refrigeration system to which the compressor is
coupled (that is, coming from the evaporator of the
refrigeration system). Subsequently, when said piston
returns from the lower dead point, in its compression
stroke, it compresses the refrigerant gas which, under
high pressure (of condensation), flows through the
discharge system and returns to the refrigeration
system to which the compressor is coupled.
Reciprocating refrigeration compressors use one way
valves to control the gas flow during operation
thereof. The valve systems contained in the head are
responsible for regulating the flowrate and optimizing
the dynamics of the gas flow during the suction and
discharge of refrigerant gas in relation to the
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compression cylinder. A suction valve controls the gas
flow coming from the suction line connected to the low
pressure side of the refrigeration system and which is
drawn into the interior of the compression cylinder,
while a discharge valve controls the already
compressed gas flow to be directed to the high
pressure side of the refrigeration system.
The suction valve is designed to be responsible not
only for regulating the gas flow during the suction,
but also in order that its opening and closing
pendular movement be synchronized with the
displacement of the piston. Actually, for a better
performance in the compression cycle, it is desired to
anticipate the opening of the suction valve (in
relation to the arrival of the piston at the upper
dead point), in order to increase the volumetric
efficiency.
The suction and discharge valves generally comprise
one or more passage orifices and vanes that are fixed
by one of the ends thereof, so that, when a pressure
differential is established through the valve, the
vane moves, allowing the passage of gas in the
required preferential direction.
There are countless embodiments of suction valve
systems adopted in reciprocating compressors,
regarding the project of the obturator, of the valve
seat, of the gas passage orifice and also the way the
valve is attached.
In the construction in which the suction valve is of
the single-piece type, made of a laminar plate to be
mounted to the valve plate, the suction valve is
usually dimensioned to have its lateral movement
restricted by head screws (figure 1), which attach the
single-piece suction valve to both the valve plate and
he head. This construction minimizes possible lateral
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and transverse movements which may alter the
positioning of the suction valve when mounted to the
valve plate. In spite of this advantage, said
construction presents a high cost due to the raw
material that is consumed in the production of said
suction valve. Furthermore, such construction requires
additional machining operations of the faces of the
blank valve plate.
In a known prior art arrangement for mounting a
single-piece suction valve, the latter is substituted
by a valve that is not constructed in a single-piece,
or valve element, which is lodged in a recess produced
in the valve plate (figure 2), the fixation of said
valve element to the valve plate being achieved by
mechanically interlocking said parts, generally by
riveting or spot welding.
Nevertheless, although not presenting the constructive
deficiencies of the single-piece suction valve, said
solution has the disadvantage of requiring an
additional process for mounting the valve plate
assembly, which is required to guarantee the correct
positioning of the valve element in the recess.
Objects of the Invention
Thus, it is an object of the present invention to
provide a valve mounting arrangement for a
refrigeration compressor, which allows providing and
maintaining, in a simple and reliable manner, the
positioning of a valve element on the valve plate.
Another object of the present invention is to provide
an arrangement as cited above, which reduces the
process steps of mounting the valve element on the
valve plate.
An additional object is to provide an arrangement as
cited above, which has a reduced cost.
Summary of the Invention
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These and other objects are achieved through a valve
mounting arrangement for a compressor of the type that
presents a cylinder defining, in its interior, a
compression chamber having an end closed by a valve
plate provided with at least one suction orifice and
at least one discharge orifice, each being selectively
closed by a respective valve element having a mounting
end portion attached to an adjacent face of the valve
plate; a bending median portion; and a sealing end
portion operatively associated with the respective
orifice on the valve plate, said mounting arrangement
comprising: a receiving recess provided on the valve
plate to lodge the mounting end portion of the valve
element; a first retaining means to be seated and
secured against said adjacent face of the valve plate,
so as to retain the mounting end portion of the valve
element in the interior of the receiving recess; and
at least one of the parts of: at least one orientation
projection, carried by at least one of the parts of
receiving recess of the valve plate and mounting end
portion of the valve element and to be fitted into a
respective orientation recess provided in the other of
said parts; and a second retaining means provided
between the receiving recess and the mounting end
portion of the valve element, so as to avoid the
latter from moving outwardly from the receiving recess
of the valve plate, before mounting the first
retaining means.
The objects of the present invention are further
achieved with a valve mounting arrangement for a
refrigeration compressor of the type described above
and which comprises: a receiving recess provided on
the valve plate to lodge the mounting end portion of
the valve element, said receiving recess presenting a
contour similar to and surrounding the contour of said
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mounting end portion, so that the latter is tightly
disposed in said receiving recess; a first retaining
means to be seated and secured against said adjacent
face of the valve plate, so as to retain the mounting
end portion of the valve element in the interior of
the receiving recess; and at least one of the parts
of: at least one orientation projection carried by at
least one of the parts of receiving recess of the
valve plate and mounting end portion of the valve
element and to be fitted into a respective orientation
recess provided in the other of said parts; and a
second retaining means provided between the receiving
recess and the mounting end portion of the valve
element, so as to avoid the latter from moving
outwardly from the receiving recess of the valve
plate, before mounting the first retaining means.
Brief Description of the Drawings
The invention will be described below with reference
to the enclosed drawings, given by way of example of
one embodiment of the invention and in which:
Figures 1 and la schematically and respectively
represent a plan view of a valve plate, when observed
from the side of the compression cylinder and
illustrating a suction orifice and a single-piece
suction valve, said valve plate and suction valve
being constructed according to the prior art;
Figure 2 schematically represents a perspective view
of a valve plate and valve element constructed
according to another prior art embodiment;
Figures 3 and 3a schematically and respectively
represent an exploded perspective view of a valve
plate, when observed from the side of the compression
cylinder and illustrating a suction orifice, a
discharge orifice and a valve element, and a suction
valve not of the single-piece type, said valve plate
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and valve element being constructed according to the
present invention;
Figure 4 schematically represents an enlarged
sectional view of the region in which the valve plate
is mounted between a top cylinder portion and a head,
for the valve plate - valve element construction
illustrated in figure 3, the mounting end portion of
said valve element being seated on the valve plate;
and
Figure 5 represents an enlarged view of the region in
which the end portion is mounted in the receiving
recess of the valve plate.
Detailed Description of the Invention
The present invention will be described in relation to
a refrigeration compressor comprising, in the interior
of a casing (not illustrated), a motor-compressor
assembly including a cylinder 1 that lodges a piston 2
reciprocating within a compression chamber 3 defined
in the interior of said cylinder 1 between a top
portion of said piston 2 and a valve plate 4 seated
onto an end portion of the cylinder 1, said prior art
valve plate 4 being described below.
The compressor further carries an electric motor (not
illustrated) that drives said piston 2 in suction and
compression strokes of a refrigerant gas of a
refrigeration system to which the compressor is
coupled, said refrigerant gas being admitted in the
interior of the compression chamber 3, from a suction
line of the refrigeration system to which the
compressor is coupled.
The prior art valve plate 4 illustrated in figures 1,
la and 2 is provided with at least one suction orifice
5 and with at least one discharge orifice 6, each
being selectively closed by a respective suction valve
7 and a discharge valve (not illustrated) carried by
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the valve plate 4.
In the prior art construction illustrated in figures 1
and la, the suction valve 7 is of the type that
comprises a flexible vane 7a, stamped in a support
blade 7b made of a material having adequate
characteristics to the operation of the flexible vane
7a during the opening and closing of the suction
orifice 5 and which is attached between a valve plate
4 and a cylinder cover 8, by appropriate means (not
illustrated). The support blade 7b is provided with
holes 7c, which receive fixation means (not
illustrated) for retaining said support blade 7b
between the cylinder cover 8 and the valve plate 4.
The cylinder cover 8 is attached to the valve plate 4,
so as to separate the high and low pressures sides and
internally define at least one suction chamber (not
illustrated) maintained in selective fluid
communication with the compression chamber 3 through
the suction orifice 5.
In the prior art construction illustrated in figure 2,
the suction valve 7 is in form of a valve element
welded to a recess 4a produced on the valve plate 4,
with a contour similar and external to the contour of
the suction valve 7 mounted in said recess 4a.
These prior art constructions present the deficiencies
already mentioned above.
As mentioned above and illustrated in the enclosed
drawings, the invention refers to a valve mounting
arrangement for a refrigeration compressor of the
above-mentioned type and which comprises at least one
valve element 10 having a mounting end portion 11
attached to an adjacent face of a valve plate 20 of
the present invention and described below; a bending
median portion 12; and a sealing end portion 13,
operatively associated with the respective orifice on
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the valve plate 20 and which in the illustrated
construction is a suction orifice 21, and the valve
element 10 is a suction valve.
In the construction of the illustrated valve element
10, the bending median portion 12 comprises a median
opening 14 aligned with a discharge orifice 22 defined
on the valve plate 20 and imparts to the valve element
10, in both its bending median portion 12 and sealing
end portion 13, a U-shape with the legs united by the
mounting end portion 11.
According to the invention, the valve element 10
presents a determined geometry defined in such a way
as to result in a vane with an optimum ratio between
stiffness and maximum bending stress, as described
ahead.
The valve element 10 of the present invention is
defined in a sheet made of flexible material with a
reduced thickness comprising an outer edge 15,
defining the external contour of said valve element
10, for example, substantially U-shaped, and an inner
edge 16 defining the contour of the median opening 14.
According to the present invention, the valve plate 20
is provided with at least one suction orifice 21 and
at least one discharge orifice 22, said valve plate 20
being further provided with a receiving recess 23 for
lodging the mounting end portion 11 of the valve
element 10, said receiving recess 23 presenting a
contour similar to and surrounding the contour of said
mounting end portion 11, so that the latter is tightly
disposed in said receiving recess 23, avoiding lateral
movements of said mounting end portion 11 in the
interior of the receiving recess 23. With this
construction, the mounting end portion 11 is retained,
by interference, in the interior of the receiving
recess 23, against lateral displacements in a seating
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plane of said parts of mounting end portion 11 and
receiving recess 23.
The valve plate 20 of the present invention is
obtained, for example, by sintering. However, the
present invention also foresees the production by
stamping or machining, the latter being the most
expensive.
In a particular form of the present invention, as
illustrated in the enclosed figures, the receiving
recess 23 presents a contour corresponding to that of
the respective valve element 10 along the whole
periphery thereof, said contour of the receiving
recess 23 maintaining a minimum clearance from the
adjacent contour of the valve element 10, in the parts
of bending median portion 12 and sealing end portion
13 of said valve element 10, so as not to interfere
with the closing and opening operations of these
portions of the valve element 10.
The valve mounting arrangement of the present
invention further comprises at least one orientation
recess 30 provided in at least one of the parts of
receiving recess 23 of the valve plate 20 and mounting
end portion 11 of the valve element 10, and at least
one orientation projection 40, carried by at least one
of the parts of receiving recess 23 of the valve plate
10 and mounting end portion 11 of the valve element
10, and to be fitted in the orientation recess 30
provided in the other part, in order to avoid relative
displacements between the valve element 10 and the
valve plate 20 in the seating plane of said parts.
Within the concept presented herein, it is possible to
make different constructions of orientation recess and
orientation projection, such as, respectively, grooves
or
through holes and saliences or pins projecting from
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the part where they are provided. Other solutions are
also possible, in which there is the provision of at
least one projection and one recess in each of the
parts of receiving recess 23 of the valve plate 20 and
mounting end portion 11 of the valve element 10.
In the illustrated constructions, the valve element 10
comprises two orientation recesses 30 in the form of
holes 17, for example through holes, which are
symmetrically provided in the longitudinal axis of the
valve element 10, each being fitted in a respective
orientation projection 40 defined in the receiving
recess 23 of the valve plate 20, in the form of a pin
24 incorporated in a single piece to the valve plate
20, projecting from the bottom face of the receiving
recess 23.
Independent of the constructive form of each
orientation projection 40, this must have a height
calculated to be at maximum equal to that of the face
of the valve plate 20, in which is defined the
receiving recess 23 carrying said orientation
projection 40, in order not to interfere with the
mounting of the valve plate 10 between the cylinder
and the cylinder cover 8.
In the present invention, the fixation of the parts
being mounted is achieved by a first retaining means
being seated and secured against the face of the valve
plate 20 carrying the valve elements 10, in order to
retain the mounting end portion 11 of said valve
elements 10 in the interior of the receiving recess 23
and by the orientation projection 40 being fitted in
the respective orientation recess 30.
In the case the valve element 10 defines a discharge
valve, said first retaining means is defined by the
cylinder cover 8, which is seated and secured onto the
valve plate 20, attaching the latter to the cylinder
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block through adequate means. In some constructions,
this mounting arrangement further presents at least
one sealing gasket 9 between the parts of cylinder
cover 8 and valve plate 20 and between the latter and
the cylinder 1.
In the case the valve element 10 defines a suction
valve, said first retaining means is defined by a top
portion of the cylinder 1. In this case, it is also
necessary to provide the present mounting arrangement
with a second retaining means provided between the
receiving recess 23 and the mounting end portion 11 of
the valve element 10, so as to avoid the latter from
moving outwardly from the receiving recess 23 of the
valve plate 10, before mounting the first retaining
means.
In a way of carrying out the present invention, the
second retaining means 50 is a liquid presenting
enough surface tension to maintain the mounting end
portion 11 of the valve element 10 retained in the
respective receiving recess 21 of the valve plate 20
upon mounting the valve. Said liquid can be, for
example, a viscous liquid, such as oil, and more
particularly, a lubricant oil of the type used in
refrigeration compressors.
In another constructive form of the present invention,
the second retaining means 50 is an adhesive that
maintains the mounting end portion 11 of the valve
element 10 retained in the respective receiving recess
23.
According to the present invention, the second
retaining means 50 is provided to operate for
retaining the valve element 10 into the receiving
recess 23 against orthogonal displacements that permit
the valve element 10 to come out from the receiving
recess 23, at least temporarily, upon mounting said
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parts to the cylinder 1.
In order to facilitate the correct mounting of the
valve element 10 to the valve plate 20, said valve
element 10 comprises an eccentric indexing means 18
provided in its mounting end portion 11, particularly
adjacent to an edge of said mounting end portion 11.
The fixation of the valve in the housing is achieved
through the joint action of at least two of the
following three factors: the actuation of the
orientation projections 40 in the orientation recesses
30, positioning the valve element 10 on the valve
plate 20 and restricting the lateral and longitudinal
movements of said valve element 10 in relation to the
receiving recess 23; the profile of the mounting end
portion 11 of the valve element 10 and the
corresponding profile of the adjacent contour of the
receiving recess 23, said profiles helping to restrict
the lateral and longitudinal movements of said valve
element 10; and the application of the second
retaining means 50, in the form of an oil or adhesive,
which is dosed and applied to the region of the
mounting end portion 11, for example, close to the
orientation projections 40, adhering the valve element
10 inside the receiving recess 23 and hindering said
valve element 10 from moving away from said receiving
recess 23.
According to the concept of the invention disclosed
herein, the present mounting arrangement guarantees
the fixation of the valve element 10 to the receiving
recess 23, at least until mounting the first retaining
means, by action of at least two of the parts of:
orientation projection 40 and respective orientation
recess 30; second retaining means 50 and receiving
recess 23, presenting a contour similar to and
surrounding the contour of the mounting end portion
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11, so that to place the latter in said receiving
recess 23.
In the construction in which the receiving recess 23
does not have a contour similar to and surrounding the
contour of the mounting end portion 11, so that the
latter is tightly disposed in said receiving recess
23, the fixation of the valve element 10 to the
receiving recess 23 is guaranteed, at least until the
first retaining means is mounted, by action of each
orientation projection 40 and respective orientation
recess 30, and also of the second retaining means 50.
In the condition in which the receiving recess 23
presents a contour similar to and surrounding the
contour of the mounting end portion 11, so that the
latter is tightly disposed in said receiving recess
23, the fixation of the valve element 10 to the
receiving recess 23, at least until mounting the first
retaining means, is guaranteed with the provision of
one or both of the parts of orientation projection 40
and respective orientation recess 30, and also of the
second retaining means 50.
The mounting arrangement of the present invention with
a valve element 10 housed in a receiving recess 23
defined in the valve plate 20 results in a cost
reduction as compared to the known prior art mounting
arrangements, since it consumes less quantity of raw
material for producing the valve element 10 and
dispenses additional machining operations of the faces
of the blank valve plate 20. Moreover, the mounting
arrangement of the present invention simplifies the
process of defining the receiving recess 23 in the
valve plate 20, which is achieved during the sintering
thereof, as well as the process for affixing the valve
element 10 in the receiving recess 23, and eliminates
the need of a fixation step, by welding the valve
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element 10, when this is a suction valve, to the valve
plate 10. The provision of an eccentric indexing means
18 in the valve element 10 allows the latter to be
correctly mounted to the valve plate 20, considering
the lamination and pre-tension of the valve.
While only one possible embodiment for the mounting
arrangement of the invention has been illustrated
herein, it should be understood that this is
exemplary, not intended to limit the inventive scope
defined in the claims accompanying the present
specification.
