Method of manufacturing plate suction valve

A method of assembling a reciprocating piston hermetic compressor including a two piece suction valve capable of being deburred by abrasive material. The reexpansion volume between the valve leaf and valve spacer is reduced to a minimum since the clearance between the valve leaf and valve spacer is reduced by the fabrication method. The valve leaf may be made of a different material than the valve spacer using the same or a different stamping tool.

BACKGROUND OF THE INVENTION 
The present invention relates generally to reciprocating piston compressors 
for compressing fluid and more particularly to such compressors having a 
cantilevered suction leaf valve. 
In a typical reciprocating piston compressor, a cylinder is defined by a 
compressor crankcase and a piston reciprocates within the cylinder to 
compress gaseous refrigerant therein. In a compressor to which the present 
invention pertains, a valve plate assembly is disposed immediate the top 
surface of the crankcase and a cylinder head mounted thereto. The valve 
plate assembly includes a suction valve operable to admit fluid into the 
cylinder during the suction stroke of the compressor and a discharge valve 
operable to exhaust fluid into a discharge space defined by the cylinder 
head during the discharge stroke of the compressor. 
With respect to the aforementioned valve plate assembly, a valve plate 
covers the cylinder and includes a suction inlet port extending 
therethrough to provide fluid communication between the cylinder and a 
suction pressure chamber in the cylinder head. A cantilevered suction leaf 
valve also known as a "flapper" valve is mounted adjacent the cylinder 
facing side of the face valve plate. An unattached end of the valve is in 
registry with the suction inlet port of the valve plate. During the 
compression stroke of the compressor, the unattached end is forced by 
pressure to sealingly cover the suction inlet port. During the intake 
stroke of the compressor, the unattached end is forced away from the valve 
plate by fluid being drawn through the suction inlet port. 
Currently, suction valves are formed of very thin metal so the flapper can 
flex open and closed against the valve plate. 
In the past, suction leaf valves were formed by stamping out a narrow slot 
between the flapper portion and the surrounding structure in a piece of 
valve steel. The width of the slot was controlled by the tooling of the 
stamping machinery. A problem with the narrow slot concerns the volume of 
gas that can be contained within the slot between the piston and valve 
plate in the compressor assembly. This volume, commonly called reexpansion 
volume, reduces the efficiency of the compressor since the fluid within 
the volume is repeatedly being compressed and expanded without producing 
any benefit. The narrower the slot is between the leaf valve and 
surrounding structure the smaller the reexpansion volume. 
During construction of the suction leaf valve, the leaf valve undergoes a 
process known as "deburring". Deburring is a process of removing the sharp 
metal or burrs from the edge of stamped pieces. During the deburring, the 
piece to be deburred is placed into a tumbler along with abrasive 
material. The tumbler is rotated to allow the abrasive to remove the sharp 
edges from the metal valve. A particular problem with these types of 
valves is that the tumbling media or abrasive cannot always reach into the 
entire narrow valve slot. This prevents the edges at the slot from being 
deburred. 
Further, if the valve edges within the valve slot are not properly 
deburred, the valve life is considerably shortened. 
Another potential problem is that abrasive material wedged between the 
valve leaf and spacer may remain there during compressor assembly. During 
compressor operation the abrasive material may interfere with proper valve 
action and reduce valve life. Also the material may become dislodged 
within the compressor and cause internal damage. 
The present invention is directed to overcoming the aforementioned problems 
associated with reciprocating piston compressors having cantilevered 
suction leaf valves. 
SUMMARY OF THE INVENTION 
The present invention overcomes the problems and disadvantages of the 
above-described prior art reciprocating piston compressors by providing an 
improved suction valve comprising a two piece valve assembly that is more 
efficient and easier to manufacture. More specifically, the present 
invention provides a two piece suction valve comprising a valve spacer and 
separate valve leaf or flapper wherein the two parts are separately 
stamped out of the same or separate stamping strips. 
The separate valve leaf and spacer of the present invention die stamp cut 
from metal strips, increase the efficiency of the compressor by decreasing 
the space between the valve leaf and spacer. This is because the entire 
leaf is stamped out by means of a die having an outer perimeter that 
defines both the outer perimeter of the valve leaf and the opening in the 
spaces that surrounds the valve leaf. This narrower space between the 
spacer and valve leaf decreases the reexpansion volume of the compressor. 
By separately making the valve leaf and spacer, different construction 
materials may be used. The present invention does not limit the valve 
spacer to be made out of the same material as the valve leaf. Reduced cost 
of the valve is possible since the valve spacer does not have to be 
fabricated out of expensive valve quality steel as does the valve leaf. 
Deburring of the valve leaf and spacer of the present invention also is 
improved by deburring the leaf and spacer separately. The abrasive 
deburring media cannot get caught or trapped between the leaf and spacer 
since they are not attached during deburring. A better and smoother finish 
on the valve leaf is possible since the entire inside and outside edge is 
available to action by the abrasive material. 
An added benefit is that stamping tool life is extended since the width of 
the stamping tool is increased. In the prior designs, the stamping tool 
had to stamp a slot that was very narrow. Any wear on the narrow tool used 
to stamp the slot would cause failure of the tool or an incomplete slot in 
the valve. The forms of the present invention allow the stamping tool to 
be much wider, therefore preventing premature tool failure. 
An advantage of the reciprocating piston compressor of the present 
invention is increased efficiency due to an accurate controlling of the 
valve stamping process. 
An advantage of the reciprocating piston compressor of the present 
invention is increased reliability since the edges of the suction valve 
possess a better finish. 
An advantage of the reciprocating piston compressor of the present 
invention is lower manufacturing cost since the improved valve spacer will 
not have to be constructed out of valve quality steel. 
The invention, in one form thereof, provides a method for making a valve 
assembly of a reciprocating piston compressor comprising the steps of 
attaching a valve leaf to a valve plate and crankcase cylinder assembly 
and attaching a separate valve spacer to the valve plate and crankcase 
cylinder assembly, wherein the valve spacer at least partially encircles 
the valve leaf. The valve plate is fastened to the compressor crankcase 
such that the valve spacer and valve leaf are disposed between the valve 
plate and crankcase. The fabrication of the valve spacer and separate 
valve leaf preferably are accomplished by die stamp cutting at least one 
strip of metal. The valve leaf and spacer may both be stamped out of the 
same spring steel metal strip or may be stamped out of separate metal 
strips. The valve spacer and valve leaf may be stamped using separate 
stamping tools or the same stamping tool. 
In one aspect of the previously described form of the invention, the valve 
spacer and valve leaf may be die stamp cut from the same piece of metal at 
the same time where the valve leaf is die stamp cut from an interior area 
of the spacer. Generally contiguous notches formed in the spacer and leaf 
permit proper locating of the valve leaf within valve spacer during 
assembly. 
In accord with another aspect of the invention, the deburring process of 
tumbling the valve leaf and valve spacers with an abrasive material to 
deburr the edges is provided. The deburring of the parts may be together 
or deburring may be conducted separately upon the valve leaf and valve 
spacers. The tumbling reduces the outer dimensions of the valve leaf while 
tumbling of the valve spacers allows enlargement of the encircling edge 
for the required clearance within the valve spacer.

Corresponding reference characters indicate corresponding parts throughout 
the several views. The exemplifications set out herein illustrate a 
preferred embodiment of the invention, in one form thereof, and such 
exemplifications are not to be construed as limiting the scope of the 
invention in any manner. 
DESCRIPTION OF THE PREFERRED EMBODIMENT 
As shown by FIG. 1, a typical prior art valve leaf and spacer plate 41 is 
constructed in one piece. This prior art valve plate 41 is die stamp cut 
to form a cantilevered suction leaf valve 42 having an attached end 43 
connecting it to spacer portion 45. The stamp cut slot 44 for cantilevered 
suction leaf valve 42 creates a problem during manufacture of the valve 
assembly 40 (FIG. 5), particularly during deburring. 
Deburring is a process of removing the sharp metal edges along the cutout 
portions of the valve plate 41 by placing the valve plate 41 within a 
tumbler 60 much like that shown in FIG. 7. Within tumbler 60, in addition 
to the valve plates, would be placed abrasive material 62 to wear down the 
sharp edges on valve plate 41. A problem encountered with this method is 
that abrasive material 62 can not enter cutout slot 44 and provide 
deburring to the edges of the cutout slot. Without adequate deburring of 
the slot edges, reliability and life of the valve is considerably reduced. 
The disadvantage with slot 44 is that it increases the reexpansion volume, 
thereby lowering the compressor efficiency. 
In an embodiment of the invention as shown in the drawings, and in 
particular by referring to FIGS. 2 and 3, a valve leaf 20 and valve leaf 
spacer 30 are shown. Valve leaf 20 and valve leaf spacer 30 are 
specifically constructed for use as the suction valve within a valve 
assembly 40 in a hermetic compressor 70 as shown in FIGS. 8 and 9. Valve 
leaf 20 preferably has two locating holes 22 for use in connecting valve 
leaf 20 within valve assembly 40. A slot 24 in valve leaf 20 allows for 
greater flexing movement during compressor operation and also allows 
discharge gases from the compressor to pass through. Valve leaf 20 is 
preferably constructed out of standard valve quality steel. 
Valve leaf spacer 30 includes an encircling edge such as centered valve 
opening 32 which substantially conforms to the shape of valve leaf 20 but 
is slightly larger. Upon assembly of valve assembly 40 (FIG. 5), valve 
leaf 20 is disposed within valve opening 32. Valve spacer 30 also includes 
a plurality of bolt holes 34 for attachment in valve assembly 40. Along 
the sides of valve opening 32 are locating holes 36. A suction gas inlet 
37 and a discharge gas outlet 38 are included in spacer 30. 
In accordance with the principles of one embodiment of the present 
invention, the valve leaf 20 and valve leaf spacer 30 are manufactured by 
conventional die stamp cutting but from separate sheets or strips as 
illustrated in FIG. 4. A strip of valve quality steel 64 is used to 
produce the valve leafs 20 while a strip of standard steel 66 is used for 
die stamping the valve leaf spacer 30. Valves 20 and spacers 30 are 
stamped out of strips 64 and 66 in a standard fashion. 
An advantage of fabricating the valve leaf 20 and spacer 30 separately is 
that it permits different materials to be used. One is not limited to only 
one type of steel for both the valve leaf 20 and spacer 30. It is more 
economical and inexpensive to fabricate only the valve leaf 20 out of 
valve quality steel, and the valve spacer 30 out of ordinary steel such as 
1010 or 1020. 
The stamping tooling used has a longer life than that used to fabricate 
prior art valves since the stamping tool can be made thicker. The prior 
tooling had to be thin enough to stamp out narrow slot 44. This made the 
tooling very susceptible to failure since the thinner tooling is weaker 
and has a shorter life. After stamping, the parts are deburred. 
The valve leaf 20 and valve leaf spacer 30 are placed in a tumbler such as 
the one shown in FIG. 7 along with abrasive material 62 to deburr any 
sharp edges and produce the required clearance between the valve leaf 20 
and valve hole 32 in the valve leaf spacer 30 by wearing away the edge. 
A clearance of approximately 0.005 of an inch between the valve leaf 20 and 
spacer 30 is preferred for proper operation of the valve assembly 40. This 
clearance is wide enough to permit movement of valve leaf 20, but is much 
narrower than slot 44 in the prior art design (FIG. 1). 
By having separate valve leafs 20 and valve spacers 30 different degrees of 
deburring are possible. Depending upon the material of the leafs 20 and 
spacer 30, the parts may need to be subjected to deburring for different 
lengths of time in order to meet the required clearances. After undergoing 
deburring the parts are ready to be assembled. 
As shown in FIG. 5, valve leaf 20 and spacer 30 are incorporated into a 
valve assembly 40. Valve assembly 40 comprises a crankcase 48 having a 
crankcase cylinder face 49 and other connected parts discussed herein. 
Adjacent the crankcase cylinder face 49 is located a valve plate gasket 
50. Upon valve plate gasket 50 is spacer 30 of the present invention. The 
valve leaf 20 is disposed within valve opening 32 of spacer 30. Connector 
means, specifically locating pins 46, accurately locate valve leaf 20 and 
spacer 30 within valve assembly 40. Locating pins 46 are disposed in holes 
22 in valve leaf 20 and locating holes 36 in spacer 30 to insure proper 
placement and orientation in valve assembly 40. These locating pins 46 are 
received into holes 47 in crankcase 48 and holes 51 in valve plate 52, as 
shown in FIG. 6. 
Over the valve leaf 20 and spacer 30 is located a valve plate 52. Upon 
valve plate 52 is attached a discharge valve 53 and its associated 
discharge valve retainer 54. Over valve plate 52 is cylinder head gasket 
56 between valve plate 52 and cylinder head 58. Cylinder head 58 is 
attached to crankcase 48 by means of bolts 72 which extend through 
cylinder head gasket 56, valve plate 52, spacer 30, and valve plate gasket 
50. Valve assembly 40, as shown in FIG. 8, is associated with a hermetic 
reciprocating piston compressor 70. 
Compressor 70 includes a housing 74 having an upper portion 76 and a lower 
portion 78, which are sealingly secured together at seam 80, as by 
welding. A motor-compressor unit 82 is resiliently mounted within housing 
74 by means of a plurality of circumferentially spaced mounting assemblies 
84. 
Motor-compressor unit 82 includes a crankcase 48 having a crankshaft 88 
rotatably received therein, and an electric motor 89 comprising a stator 
90 and a rotor 92. Stator 90 is provided with windings 94, which are 
connected to an external current source by means of electrical leads 95, 
terminal block 96, and hermetic terminal 98. Rotor 92 has a central 
aperture 102 provided therein into which is secured crankshaft 88 by an 
interference fit. 
Crankshaft 88 includes an eccentric portion 104 which is received in a 
closed loop end 106 of connecting rod 108. Connecting rod 108 is also 
connected to a piston 110 by means of a wrist pin 111. Crankcase 48 
includes a cylinder bore 112, defined by cylinder side wall 113, in which 
piston 110 is reciprocatingly received. Cylinder 50 is covered by valve 
assembly 40. 
In accordance with an alternative embodiment of the current valve leaf and 
valve leaf spacer arrangement, FIG. 10 shows an alternative construction. 
In this case, valve leaf 120 is constructed by stamping out the valve leaf 
120 from the inside of valve leaf spacer 122. The shape of valve leaf 120 
is substantially the same as the first embodiment, except for generally 
contiguous semi-circular notches 124 in valve leaf 120 and semi-circular 
notches 126 in valve leaf spacer 122. These notches permit locating pins 
128 to be inserted between the valve leaf 120 and valve leaf spacer 122 
during assembly of the valve assembly 40. The notches 124 and 126 allow 
for proper location and placement of valve leaf 120 within spacer 122. 
Spacer 122 also has a suction inlet 125 and a discharge outlet 127. 
The stamping of this alternative embodiment of the present invention has an 
additional advantage over the previous embodiment discussed above. The 
method shown in FIGS. 10 and 11 can use either one stamping tool or two. 
In the preferred case the tooling would simply stamp the valve spacer 112 
and valve leaf 120 out of a strip of metal at the same time. In another 
case the valve spacer 122 could be stamped first from a strip and then 
another tool would stamp the valve leaf 120 from the spacer 122. 
Alternatively the valve leaf 120 could be stamped first then the spacer 
122. After the stamping operation is complete, the parts are deburred as 
above. 
This alternative design of the leaf valve 120 permits leaf valve 120 and 
leaf spacer 122 to be stamp cut from a single blank with common locator 
pins thus providing more accurate location and requiring less clearance 
between the parts. This helps increase the capacity of the compressor 
since reexpansion volume is decreased and the efficiency of the compressor 
is thereby increased. 
While this invention has been described as having a preferred design, the 
present invention can be further modified within the spirit and scope of 
this disclosure. This application is therefore intended to cover any 
variations, uses, or adaptations of the invention using its general 
principles. Further, this application is intended to cover such departures 
from the present disclosure as come within known or customary practice in 
the art to which this invention pertains and which fall within the limits 
of the appended claims.