Single piece gasket valve plate assembly

A single piece gasket valve plate assembly for sealing and separating assembly parts secured to the valve plate of a reciprocating piston compressor. The gasket includes a compressible peripheral portion for sealing and separating the valve plate to the cylinder head. The device also includes compressible central portions, which are spaced from and integral with the peripheral portion, wherein the central portions members are adapted to encircle the suction ports of the valve plate to seal and separate the suction ports from the discharge ports. A connecting portion extending through the discharge chamber connects the peripheral portion of the gasket to the central portions.

BACKGROUND OF THE INVENTION 
This invention relates to a hermetic reciprocating piston compressor, and 
in particular to a compressor having a single piece gasket valve plate 
assembly associated therewith. 
Reciprocating compressors generally use a unitary valve plate to cover all 
the cylinders of the compressor. The valve plate includes a suction port 
and discharge port, which are respectively in fluid communication with a 
suction pressure chamber and a discharge pressure chamber of a cylinder 
head. Such valve plates are generally sealed to the cylinder head of a 
compressor by means of several gaskets. For example, in a dual piston 
assembly, three gaskets are used: one outer gasket to seal the periphery 
of the valve plate to the cylinder head, and two inner ring gaskets to 
seal each cylinder suction valve area to its corresponding suction 
chamber. 
Valve plates and cylinder head assemblies have become relatively complex 
for certain compressors and can be quite costly to assemble and 
manufacture. Therefore, it is important to reduce the number of steps 
needed to assemble these compressors. 
The use of multiple valve plate gaskets in compressors has been effective 
to seal and separate assembly parts. Notwithstanding this success, efforts 
are continuously directed toward increasing the rate of compressor 
assembly production. Considerations of manufacturability and costs impact 
on the desirability of the aforementioned prior art gaskets. For example, 
during initial manufacturing of the compressor assembly, the outer gasket 
must be installed independently of the inner ring gaskets. In addition, 
the inner ring gaskets may get out of proper alignment with the valve 
plate during assembly, especially during very high rates of automated 
production. Furthermore, the ring gaskets may adhere together during 
production resulting in two ring gaskets in the place where only one 
should be. Consequently, the next valve plate on the assembly line may 
have no gasket installed therein. 
Thus, not only does the present use of multi-piece gaskets result in a 
greater time of manufacture and assembly, but may also result in the 
assembly of compressors with an improper number or placement of the 
separate gaskets. 
SUMMARY OF THE INVENTION 
The problems and disadvantages of the aforementioned compressor valve plate 
assembly having multiple gaskets are overcome by the present invention 
wherein a single, unitary gasket is secured to the valve plate assembly to 
provide all necessary sealing of the head to the valve plate during 
assembly of the compressor. More particularly, the invention provides a 
single, unitary gasket which seals the cylinder head to the valve plate, 
and simultaneously seals and separates the suction chamber from the 
discharge chamber. 
The invention further provides a method of assembly of a valve plate and 
gasket in a reciprocating piston compressor. 
One advantage of the valve plate assembly according to the present 
invention is that one relatively large gasket is provided, which allows 
more consistent and reliable alignment with the valve plate. 
Another advantage of the present invention is that the unitary gasket is 
larger than the separate ring gaskets of the prior art and, thus, are less 
likely to adhere together so that a single gasket is consistently provided 
for each valve plate. 
A further advantage of the present invention is that only one manufacturing 
step is needed to install the gasket instead of two or more steps as 
required for the gaskets of the prior art. The elimination of the 
additional steps reduces assembly costs. 
The present invention, in one form thereof, comprises a method for 
assembling a gasket and valve plate assembly. The compressor includes a 
crankcase with a top surface, two cylinder bores disposed in the crankcase 
and a piston located in each of the cylinder bores. A crankshaft drives 
the pistons. A cylinder head having a bottom surface is adapted to engage 
the top surface of the valve plate. In addition, the cylinder head 
includes two suction and discharge chambers for fluid communication of 
each chamber with its respective cylinder. A valve plate mounted on the 
top surface of the crankcase includes suction ports and discharge ports. 
The method of assembly comprises providing a unitary gasket having a 
peripheral portion, a central portion in spaced relationship with the 
peripheral portion, wherein each central portion is adapted to encircle 
one of the suction ports, and, two connecting portions preferably 
extending through the suction or discharge chambers to connect the 
peripheral portion to the two central portions. A discharge valve is 
mounted to the valve plate. The valve plate gasket is then aligned in 
registry with the valve plate so that the peripheral portion extends along 
the perimeter of the valve plate and the central portions encircle the 
suction ports. A discharge valve retainer is assembled to the plate, and 
the cylinder head is then mounted on the valve plate such that the unitary 
gasket seals and separates the cylinder head from the valve plate, and 
simultaneously seals and separates the suction chambers from the discharge 
chambers. 
The present invention, in one form thereof, comprises a twin cylinder 
reciprocating piston compressor having a crankcase, two cylinder bores 
disposed in the crankcase, and a piston located in each of the bores. A 
crankshaft drives the pistons. There is also provided a cylinder head and 
a valve plate which is located between the crankcase and the cylinder 
head. The valve plate includes suction ports and discharge ports to 
provide fluid communication with the cylinder bores. A unitary valve plate 
gasket is located between the cylinder head and the valve plate. The 
gasket includes a compressible peripheral portion and two annular central 
portions, which are spaced from the peripheral portion, each adapted to 
encircle a suction port. Two correcting portions of the gasket preferably 
extend through the discharge or suction chambers to connect the peripheral 
portion with the two central portions. 
It is an object of the present invention to provide a method for consistent 
and reliable placement of one or more gaskets on a valve plate assembly. 
It is another object of the present invention to provide a unitary gasket 
that is less likely to adhere to other gaskets during automated assembly 
so that a single gasket is consistently available for sealing each valve 
plate. 
Yet another object of the present invention is to reduce the number of 
manufacturing steps needed to attach several gaskets to the valve plate of 
a compressor.

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 disclosure or the scope of the 
invention in any manner. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawings, and in particular to FIG. 1, there is shown a 
hermetically sealed, twin cylinder reciprocating piston compressor 10 of 
the type to which the present invention is applicable. Compressor 10 
includes a sealed compressor housing 12 encapsulating the motor compressor 
unit 13. Disposed within housing 12 is a crankcase 14 supporting a 
crankshaft 16 which is driven by motor 18. Shock mounts 20 attached to 
crankcase 14 and housing 12 suspend the compressor components within 
housing 12. 
By way of illustration, and without limitation, orientation of compressor 
10 in the illustrated preferred embodiment is with crankcase 14 suspended 
vertically below motor 18. Crankshaft 16 within crankcase 14 drives 
connecting rods 22, which are in turn connected to pistons 24 within 
cylinders 26. Cylinders 26 extend through the top surface of crankcase 14. 
A cylinder head 28 having a bottom surface 29 is assembled onto the top 
surface of crankcase 14 by means of bolts (not shown). A valve plate 30, 
to which discharge valves 78 are mounted (FIGS. 4 and 5), is interposed 
between cylinder head 28 and crankcase 14. FIG. 1 shows discharge valve 
retainer 32 as is well known in the prior art. 
Cylinder head 28 includes discharge chamber 34 and suction chamber 36. 
During operation of compressor 10, the reciprocating action of pistons 24, 
together with discharge valves 78 and suction valves 31 mounted on valve 
plate 30, produce regions of discharge pressure and suction pressure in 
chambers 34 and 36, respectively. Referring to FIG. 3 for a more detailed 
description of cylinder head 28, there are shown multiple head bolt 
apertures 38, suction inlet 40 and discharge outlet 42. Also shown are 
centrally located suction ports 44 and discharge ports 46 spaced around 
suction ports 44 which are located substantially over cylinders 26 when 
compressor 10 is assembled. Conventional suction valves 31 and discharge 
valves 78 are attached to valve plate 30 in operative fashion. Valve plate 
30 is preferably made of sintered metal, therefore enabling the forming of 
details without need for machining. 
FIGS. 2 and 5 illustrate valve retainer 32 including a first portion 48 and 
a second portion 50, both with generally annular shapes. Portions 48 and 
50 are secured to valve plate 30 by rivets 52a, 52b, 53a, and 53b. 
Portions 48 and 50 include segments 48a and 48b, and 50a and 50b, which 
extend from riveted portions 47 and 49, respectively, and curve away from 
valve plate 30. Portions 48 and 50 terminate at ends 54 and 56. Located 
adjacent valve plate 30 are discharge valves 78, each associated with a 
discharge port 46. U.S. Pat. No. 4,721,443, which is incorporated herein 
by reference, discloses the discharge valve structure in detail. 
Referring to FIG. 2, a single unitary gasket 58 is shown and comprises a 
generally planar peripheral portion 60 including raised bead 62. In the 
preferred embodiment, gasket 58 has a 0.005 inch steel base with a 0.0025 
inch Buna-N coating on each side. Gasket 58 further includes anchor leg 
portion 64, which is generally planar and includes raised bead 66. 
Apertures 68 are provided in both peripheral portion 60 and anchor leg 
portion 64 for alignment with head bolt holes 38 of valve plate 30. 
Gasket 58 also includes inner rings 70 including a raised bead 72. Inner 
rings 70 encircle suction ports 44 to seal and separate fluid from suction 
chamber 36 and discharge chamber 34. Inner rings 70 are integral with 
peripheral portion 60 and anchor leg portion 64 by intermediate connecting 
portions 74a, 74b and 76a, 76b. Connecting portions 74a and 76a are 
integral with and respectively connected to respective diametrically 
opposed sides of peripheral portion 60 and inner rings 70. Similarly, 
connecting portions 74b and 76b are integral with and respectively 
connected to respective diametrically opposed sides of anchor leg portion 
64 and inner rings 70. 
As shown in FIG. 5, raised bead 72 seals discharge cavity 34 from the 
suction cavity 36. As shown in FIG. 4, inner ring 70 seals suction chamber 
36 from discharge chamber 34. Discharge valve 78 is located beneath 
intermediate portion 74b of gasket 58. Resting on intermediate portion 74b 
is valve retainer 32. Rivets 52a and 53a extend through valve retainer 32, 
intermediate portion 74b of gasket 58, and discharge valve 78, thus 
securing gasket 58 to valve plate 30. The gasket inner ring portions 70 
are offset to account for the thickness of discharge valves 78, which are 
disposed on the surface of valve plate 30. This prevents the inner ring 
portions 70 of the gasket from being reformed during assembly and riveting 
(FIG. 4). 
An important aspect of the present invention relates to a method of 
assembling the compressor using the unitary valve plate gasket. The method 
comprises the steps of locating the discharge valves 78 and aligning 
gasket 58 it in registry with valve plate 30 so that peripheral portion 60 
extends along the perimeter of valve plate 30 and that inner rings 70 
encircle suction ports 44. Valve retainer 32 is then aligned in registry 
around suction ports 44 such that the apertures (not shown) in valve 
retainer 32 are located over connecting portions 74a, 74b and 76a, 76b. 
Valve retainer 32 and gasket 58 are secured to valve plate 30 by any 
suitable means, such as rivets 52a, 52b and 53a, 53b. Thus, the valve 
plate 30, discharge valve 78, valve retainer 32 and gasket 58 can be 
assembled as a subassembly at a position off the main assembly line during 
production. It is also possible to preassemble the suction valve 31 to 
pins (not shown) extending downwardly from valve plate 30. The valve plate 
assembly 30 is attached to the top surface of crankcase 14. Cylinder head 
28 is then mounted on valve plate 30 such that peripheral portion 60 of 
gasket 58 seals and separates valve plate 30 from cylinder head 28, and 
inner rings 70 seal and separate suction chamber 36 from discharge chamber 
34. 
While this invention has been described as having a preferred design, it 
will be understood that it is capable of further modification. This 
application is, therefore, intended to cover any variations, uses, or 
adaptations of the invention following the general principles thereof and 
including such departures from the present disclosure as come within known 
or customary practice to which the invention pertains and fall within the 
limits of the appended claims.