Pumps – Combined
Reexamination Certificate
2001-07-06
2003-12-30
Tyler, Cheryl J. (Department: 3746)
Pumps
Combined
C210S167150, C210S171000, C210S462000, C062S118000, C062S149000
Reexamination Certificate
active
06669451
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to apparatus and devices to improve the long term performance of automotive air conditioning systems. More particularly, this invention pertains to a Compressor Inlet Port (CIP) filter plate. The CIP filter plate is an improved apparatus and method for removing potentially damaging debris from the low suction side of an air conditioning circuit.
The current rate of failures for rebuilt automotive air conditioning compressors has been estimated at about 20%. The costs of these failures affect everyone from the compressor rebuilders to the customer that has paid for the failed compressor.
FIG. 1
shows a schematic view of an automotive air conditioning system
100
. Under normal operating circumstances, the refrigerant
102
in the air conditioning system
100
moves in only one direction as indicated by the refrigerant flow direction arrow
101
. Unless some internal failure occurs to the air conditioning compressor
104
, the refrigerant
102
will always move from the compressor
104
through the suction hose assembly
140
through the condenser
105
through the orifice filter
106
through the evaporator
108
and then back to the compressor
104
. The orifice filter
106
can be designed to restrict flow and also to provide a filtering function to stop any debris large enough to damage a compressor from circulating in the air conditioning system
100
. Air conditioning systems
100
can also have additional components such as dryers, accumulators, VIR valves and mufflers which are not discussed in this example. The locations of these or other additional components will vary from manufacturer to manufacturer and are thus omitted from this paper.
FIG. 2
shows a typical compressor
104
failure in an air conditioning system
100
. First, the compressor
104
begins an internal failure. Second, the debris
116
from the internal failure of the compressor
104
moves into the high-pressure side
110
of the air conditioner system
100
. This debris
116
is generally stopped by the orifice filter
106
. This initial failure of the compressor
104
can continue for quite some time. In the next major step, the compressor
104
fails internally to the extent that the debris
116
, which has accumulated in the high-pressure side
110
, is carried by the refrigerant
102
, as the refrigerant moves backwards through the compressor
104
to the low-pressure side
112
of the air conditioning system
100
, as indicated by refrigerant flow direction arrow
101
. The low-pressure side
112
normally operates in the 30 PSI range, while the high-pressure side
110
normally operates in the 200 PSI range. So, the difference in pressure between the two sides can normally be in the 170 PSI range during this reverse flow of refrigerant. Thus, this reversed flow of debris
116
is under significant difference pressure as it enters the low-pressure side
112
and accumulates in low-pressure side components such as the suction hose assembly
140
and the evaporator
108
of the air conditioning system
100
. Due to the high differential pressure of the reverse flow, the debris
116
moves rapidly and with enough force to cause some of the debris
116
to become imbedded into the flexible hose part of the suction hose assembly
140
. Some debris
116
will also accumulate between the flexible hose material and the flexible hose fittings. This debris
116
also accumulates in other components such as the dryer (not shown) and the evaporator
108
. This complete failure of the compressor
104
results in the need for a system repair.
The normal sequence of repair procedures for an air conditioning system
100
, begins by removing the compressor
104
. Next, one removes the orifice filter
106
and the dryer (not shown). Then one will flush the air conditioning system
100
, replace the dryer (not shown) replace the orifice filter
106
, and finally, replace the compressor
104
and recharge the air conditioning system
100
with refrigerant
102
. This will generally place the air conditioning system
100
back into an operating order. However, no amount of flushing will remove all of the debris
116
, which has become imbedded into the flexible hose material of the suction hose assembly
140
and is trapped between the flexible hose and the hose fittings. Over some period of time (due to pressure and temperature changes) some of the imbedded and trapped debris
116
will loosen and be carried by the refrigerant
102
through the compressor inlet port connection
132
and into the compressor inlet suction port
130
of the compressor
104
. This will very often cause another compressor
104
failure. The solution to this problem is to install a filter
240
into the low-pressure side of the air conditioning system
100
. The present invention provides this filter
240
and eliminates the problems associated with the compressor inlet port filters and the press-into-hose block filters which are currently on the market.
Methods and devices presently exist to accomplish the removal of debris
116
from the low-pressure side
112
of an air conditioning system
100
. There include several types of filters to trap debris before it can enter the compressor.
GENERAL MOTORS CORP. (trademark) and other manufacturers have installed filter screens in several models of air conditioning compressors. These filters are generally installed on the inlet or outlet ports of the compressors. GENERAL MOTORS CORP. (trademark) has previously used a filter screen on the inlet port for filtering debris from the refrigerant flow. This protects the compressor from debris, but doesn't allow for the possibility for failure of other components. Generally, the filter cannot be cleaned without removing and sometimes disassembling the compressor.
Another method of installing a filter in an existing air conditioning system relies on pressing a small mesh filter into the suction port of a suchtion hose assembly (also known as a hose block) in a manner much like the GENERAL MOTORS CORP. (trademark) method of installing a filter into an actual compressor. This hose block filter system is available as a kit with different size filters and a small mechanical press designed to press the filter into the hose block suction port. There are several problems with this method above those already described above. First, the mechanical press is designed primarily for GENERAL MOTORS CORP. (trademark) type hose blocks and is difficult or impossible to use for other applications. Second, the filters must be made in different diameters and sizes for different styles of compressors and the use of the wrong diameter filter could result in damage to the hose block or the compressor. Third, the tolerances in the diameter of the filters are critical and can vary due to manufacturing processes and the different metals, such as aluminum and steel, involved in different applications. Fourth, hose blocks made by different companies for aftermarket parts might not have been made to the same dimensions as the original equipment part. Fifth, the cleaning of the debris from the filter requires removal of the filter from the hose block which often results in destruction of the filter. Sixth, because of the press-in interference fit and mounting ring of this design, the filter reduces the effective size of the port and further restricts the flow of the refrigerant. On the majority of GENERAL MOTORS (trademark) vehicles where the filter would be installed, the outside diameter of the filter is 0.510 inch. The suction hose assembly connector internal diameter
134
is 0.500 inch, resulting in a flow area of 0.196 sq. in. The inside diameter of the filter is approximately 0.415 inch for flow area of 0.135 sq. in. Thus, the area that the refrigerant must pass through has been reduced from 0.196 sq. in. to 0.135 sq. in. This is a reduction in area of approximately 31%. Thus, this press-fit filter installation provides a significant reduction in the area for refrigerant flow and thereby increases t
Bayless Howard H.
Sayoc Emmanuel
Tyler Cheryl J.
Waddey & Patterson
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