Measuring and testing – Gas analysis – Gas of combustion
Reexamination Certificate
2000-10-12
2002-05-07
McCall, Eric S. (Department: 2855)
Measuring and testing
Gas analysis
Gas of combustion
C073S118040
Reexamination Certificate
active
06382014
ABSTRACT:
FIELD OF THE INVENTION
The present invention is a portable exhaust emissions measurement system for vehicles and, more specifically a Real-time On-road Vehicle Emissions reporting system which continuously measures, displays, and records the quantity of gaseous emissions (HC, CO, CO
2
, NO, and O
2
), in grams/miles driven as well as fuel economy, engine and vehicle operating parameters, engine air/fuel ratio, and road grade, all at a user-selectable update rate. The present invention also relates to a flowmeter module for utilization in the system.
The PRIOR ART
The numerical exhaust gas emission standard established by the United States Environmental Protection Agency (EPA) apply to vehicles tested using the Federal Test Procedure (FTP). The FTP is conducted in a laboratory on a dynamometer under controlled environmental conditions where the vehicle is “driven” over a specific speed-time trace while the emissions are sampled. The same speed-time trace is used in testing all passenger cars and light-duty trucks and ideally represents typical in-use driving. During the test, the dynamometer applies steady-state and inertial loading on the vehicle simulating actual road-loading and dynamic loading encountered on the road for the same vehicle speeds. A constant volume sampler (CVS) is used to dilute the exhaust gas with air in such a way that the diluted gas flow rate is held constant as the vehicle's exhaust gas flow rate varies and to obtain a proportionate sample of the diluted exhaust gas during each of the three phases of the test. In this way, the sample's concentration of each pollutant is essentially proportional to the mass emissions of that pollutant.
In the case of vehicles employing heavy-duty engines, such as tractor trailer trucks and city buses, the associated EPA emission standard applies to the vehicle's engines which are emission tested on an engine dynamometer while operated over the EPA “transient test”. The emissions sampling system and CVS are similar to that described above for passenger cars. But, the engine to be tested is attached to the engine dynamometer which applies a prescribed torque and engine speed. The engine must be removed from the associated vehicle before testing, if installed. Sometimes vehicle-based electronic sensors which are inputs to the engine's fueling system, such as a vehicle speed sensor, must be left disconnected or must have simulated values during the emissions test. This may lead to emissions measurements which differ from real-world values.
For a manufacturer to obtain a certificate of conformity permitting the sale of a particular family of vehicles or engines, the manufacturer must demonstrate compliance with applicable EPA emission standards. A major part of the demonstration for passenger cars and light-duty vehicles is passing the FTP and/or heavy-duty engines is passing the transient test. Another, and usually opposing, goal for a manufacturer to meet is maximizing vehicle performance or fuel economy. Because the two goals are usually mutually opposed, and since the FTP and transient test are so well defined and repeatable, meeting the certification emissions standards often becomes a process of “tweaking” the calibration values used by the vehicle's electronic fuel injection system until the numerical emissions standards are satisfied with just enough margin to “pass” the FTP and maintain “passing” levels for the “useful life” of the vehicle.
When the calibration for a particular family of vehicles is “tweaked” to pass the FTP, test results do not necessarily reflect the vehicular emissions which result from driving the same vehicle on the road even with the same environmental conditions and vehicle speed schedule. The emissions are dependent not only on the speeds, number of miles and grades driven, but also on the particular driver, familiarity with the course being driven, traffic conditions, etc.
It is important for a responsible vehicle manufacturer to know the actual on-road emissions performance of a vehicle under various competing calibrations and designs so they have the opportunity to make environmental considerations one of the parameters by which they choose a final design or calibration. It is also important for emissions regulators to monitor the emissions performance of vehicles from each of the manufacturers on the road. With today's sophisticated electronic engine controls, road test data is necessary to determine the effectiveness of the FTP and transient test in helping maintain clean air, as well as for estimates of the emissions inventories. It is only by knowing the actual on-road emissions of vehicles that effective policy can be developed regulating those emissions.
To monitor the emissions performance of vehicles on the road, a user-friendly, portable, and easily transferable on-road emissions measurement system is needed. Ideally, installation of such a system would not require modification of the vehicle to be tested. Further, the emissions measurements of any system must agree well with laboratory FTP testing when both systems are operated concurrently.
Vehicular, on-board gas emission monitoring systems are disclosed in U.S. Pat. No. 5,099,680 issued to Fournier et al, U.S. Pat. No. 5,105,651 issued to Gutmann and U.S. Pat. No. 5,709,082 issued to Harris et al. However, none of these prior art on-board systems measures actual exhaust gas flow rate or provides an instrument module which can be easily transferred between vehicles.
U.S. Pat. No. 5,099,680 discloses an on-board system for analysis of a plurality of exhaust gas components (column 3, lines 45-47) and interfaces with the engine computer (column 3, lines 15-18). This prior art system contemplates the calculation of vehicle emissions in grams per mile, apparently based on vehicle speed and engine displacement, as described at column 4, lines 3-20.
U.S. Pat. No. 5,105,651 discloses an on-board system in the embodiment of FIG.
2
. Carbon monoxide and hydrocarbon content of the exhaust gas is monitored (column 4, lines 28-30) and exhaust gas analytical data is correlated with vehicle operation as described at column 6, line 42 to column 7, line 23.
U.S. Pat. No. 5,639,957 notes the 30-50% error in calculation of emissions of gaseous pollutants due to the difference between theoretical and actual values for exhaust gas flow. This prior art reference proposes an improved calculation for determination of theoretical exhaust gas flow.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a mobile, on-board emissions testing system which is transferrable between different vehicles, which provides for a real-time determination of mass flow rates of various gaseous pollutants based on the actual exhaust gas flow rate and which requires no modifications to the vehicle to be tested.
It is another object of the present invention to provide such an emissions testing system in which sensors required to come into contact with the exhaust gas are all incorporated into a module which may be detachably mounted on a vehicle and readily transferred from one vehicle to another.
It is a further object of the present invention to provide such a system with the capability for determination of vehicle operating parameters and correlation of those vehicle operating parameters with pollutant mass flow rates in real time.
It is yet another object of the present invention to provide such a system inclusive of a global position system receiver for continuously monitoring vehicle location and for correlating said pollutant mass flow rates with vehicle driving cycle or driving schedule.
In order to achieve the foregoing objects the present invention provides a mobile vehicle, on-board testing system, including a module designed to be detachably mounted on a vehicle to be tested and support means for detachably fixing the module to a body portion of the vehicle. Connection means, preferably including an elastomeric boot, allows for detachably connecting the module to the exhaust pipe of the vehicle
Lorusso & Loud
McCall Eric S.
The United States of America as represented by the Adminstrator
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