Drying and gas or vapor contact with solids – Apparatus – With means to treat gas or vapor
Reexamination Certificate
2003-08-05
2004-09-07
Lazarus, Ira S. (Department: 3749)
Drying and gas or vapor contact with solids
Apparatus
With means to treat gas or vapor
C034S069000, C034S218000
Reexamination Certificate
active
06785980
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to an improved compressed air supply system particularly suited for use in heavy vehicles such as trucks, and more particularly to such a system which incorporates an air dryer with integrated blow-through capabilities.
BACKGROUND OF THE INVENTION
Compressed air systems incorporating air dryers have been used to supply air in heavy vehicle air brake systems for many years. The advantages of clean arid dry air in air brake systems has long been recognized, as moisture entrained in the air brake system may during cold weather operation cause the components of the air brake system to freeze, thus rendering the system inoperable. These prior art air dryers normally include a desiccant material through which the compressed air flows. When the vehicle air compressor has charged the vehicle air reservoirs to a sufficient pressure level, the compressor is unloaded so that the compressor no longer compresses air. When the compressor is unloaded, a signal is transmitted to a purge valve which causes stored compressed air to backflow through the desiccant at a controlled rate to regenerate the desiccant. The air used to regenerate the desiccant can be either from compressed air stored in an integral purge volume within the air dryer or from compressed air stored in a separate reservoir.
Most prior art compressed air systems for heavy vehicle air brake applications use at least three reservoirs. A typical prior art system
110
, as shown in
FIG. 1
, includes a compressor
112
which feeds compressed air to the air dryer
114
which after flowing through the desiccant bed is fed to a remote supply reservoir
116
. The supply reservoir
116
is connected to feed compressed air to a primary reservoir
118
, a secondary reservoir
120
and sometimes to an auxiliary reservoir
122
. The primary
118
, secondary
120
and/or auxiliary
122
reservoirs feed pneumatic circuits
124
which can control the air brake system of the vehicle. For protection from loss of air pressure the primary
118
, secondary
120
and auxiliary
122
reservoirs each include a check valve
126
,
128
,
130
in their pneumatic connections to the supply reservoir
116
. The check valve
130
of the auxiliary reservoir
122
may also include a pressure protection valve and the supply reservoir
116
may include a safety valve
132
so as to avoid overpressure situations. A pneumatic control line
134
extends from the supply reservoir
116
to an air pressure governor
136
which controls loading and unloading of the air compressor
112
and recharging of the air dryer
114
.
This typical prior art design, however, suffers from a number of disadvantages. The system is complex, having four reservoirs, a separate governor, an air dryer, a safety valve, three check valves (one of which also includes a pressure protection valve), and a control line. As such, not only is the system relatively costly to construct initially, but it is relatively costly and time-consuming to maintain. Moreover, the complex system is prone to failure because of the number of components which may malfunction. A simplified design would be far more desirable.
Attempts have been made to obviate at least some of the disadvantages of the prior art systems discussed above. U.S. Pat. No. 6,074,462 (“the '462 patent”) represents one such attempt. The '462 patent discloses an air dryer and reservoir system
210
(shown in
FIG. 2
) for providing compressed air from an air compressor
212
on a heavy motor vehicle which includes an air dryer
214
connected to receive compressed air from the air compressor
212
and a secondary reservoir
216
, including an integral purge volume, for storing compressed air which passes through the air dryer
214
, with the air dryer
214
and the secondary reservoir
216
being securely attached to a housing to form an integral air dryer reservoir module. A primary reservoir
218
for storing compressed air from the air dryer
214
is located remotely from the air dryer reservoir module. The air dryer
214
has integrated therewith a governor which controls loading and unloading of the air compressor
212
. Also integrated with air dryer
214
are two pressure protection valves, one for each of primary reservoir
218
and secondary reservoir
216
, which allow for the simultaneous purging of the air dryer
214
using both primary reservoir
218
and secondary reservoir
216
.
While the system disclosed in the '462 patent obviates some of the deficiencies of the prior art system shown in
FIG. 1
by providing a system which is simplified in some respects, it suffers from disadvantages of its own. Integrating the pressure protection valves associated with primary reservoir
218
and secondary reservoir
216
with the air dryer
214
unnecessarily complicates air dryer
214
and makes servicing and/or replacement of the pressure protection valves more difficult. Moreover, providing both primary reservoir
218
and secondary reservoir
216
with pressure protection valves (whether they be integrated with air dryer
214
or not) such that both reservoirs
218
,
216
are used to purge the system complicates the system, and disadvantageously dictates that both reservoirs lose pressure during a purge operation.
What is desired, therefore, is a compressed air supply system which is suitable for use in heavy vehicles such as trucks, which is less complex than known systems, which is less costly to construct initially and less costly and time-consuming to maintain relative to known systems, which is less prone to failure relative to known systems, which allows for simplified servicing and/or replacement of various system components, including pressure protection valves, and which allows at least one reservoir to maintain its initial pressure during a purge operation.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a compressed air supply system which is suitable for use in heavy vehicles such as trucks.
Another object of the present invention is to provide a compressed air supply system having the above characteristics and which is less complex than known systems.
A further object of the present invention is to provide a compressed air supply system having the above characteristics and which is less costly to construct initially and less costly and time-consuming to maintain relative to known systems.
Still another object of the present invention is to provide a compressed air supply system having the above characteristics and which is less prone to failure relative to known systems.
Yet a further object of the present invention is to provide a compressed air supply system having the above characteristics and which allows for simplified servicing and/or replacement of various system components, including pressure protection valves.
Still yet a further object of the present invention is to provide a compressed air supply system having the above characteristics and which allows at least one reservoir to maintain its initial pressure during a purge operation.
These and other objects of the present invention are achieved by provision of a compressed air supply system for a heavy motor vehicle. In one embodiment, the system includes a compressor for supplying compressed air and an air dryer connected to receive compressed air from the air compressor. The air dryer includes a desiccant bed through which the compressed air flows to provide dry compressed air, and a blow-through valve operable to connect the desiccant bed to atmosphere. A secondary reservoir located remotely from the air dryer is connected to receive dry compressed air from the air dryer, and a primary reservoir located remotely from the air dryer is connected to receive dry compressed air from the air dryer. Control components integral with the air dryer are provided for controlling a charging operation by controlling air flow from the air compressor through the air dryer for charging the primary reservoir and the secondary reservoir with dry compresse
Haldex Brake Corporation
Lazarus Ira S.
O'Malley Kathryn S.
St. Onge Steward Johsnton & Reens LLC
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