Simple method of measuring nitrogen oxide in running vehicles

Details Simple method of measuring nitrogen oxide in running vehicles Simple method of measuring nitrogen oxide in running vehicles

2000-09-12

2003-09-16

Lefkowitz, Edward (Department: 2855)

Measuring and testing

Simulating operating condition

Marine

C073S023310

Reexamination Certificate

active

06619107

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a simple method of measuring the weight of nitrogen oxide emitted from an engine of a vehicle such as a motorcar running on an actual road surface.
DESCRIPTION OF THE PRIOR ART
As is well-known, nitrogen oxide (hereinafter referred, to as “NO
x
”) is one of the components determined as an air pollutant among gases (hereinafter referred to as “exhaust gas”) emitted from an engine of a vehicle, e.g., motorcar. The concentration of NO
x
contained in the exhaust gas from the engine is greatest when operating in a city in terms of speed and load and is lower in other areas. It is therefore necessary to apply a moderate load to a motorcar when measuring the NO
x
emission.
In view of this, conventionally a motorcar is mounted on a chassis dynamometer, and allowed to run in accordance with a predetermined running pattern. The speed; torque and the like of the engine are regulated to apply a proper load to the motorcar, and a NO
x
analyzer, such as a chemiluminescent detector (CLD) is used to measure NO
x
contained in the exhaust gas.
However, in the aforementioned conventional technique, considerably large-scale equipment such as a chassis dynamometer is required in addition to a NO
x
analyzer. Facilities required for measurement increase measurement costs. The measurement of NO
x
using the chassis dynamometer unit is primarily conducted to measure NO
x
of motorcars, e.g., new cars, which have not yet been run. Motorcars which have been put to use, namely, the so-called used cars are usually not subjected to measurement using the chassis dynamometer unit. It is to be noted that the used car is measured in a fact-finding survey but its proportion is relatively low.
As aforementioned, to measure the concentration and weight of NO
x
emitted from a motorcar, the measurement is preferably made in such a condition that a proper running load is applied to the motorcar.
Meanwhile, applicant has applied a patent entitled “Simple Method Of Measuring Nitrogen Oxide In Running Vehicles” on Jan. 29, 1999 as a technique for simply measuring the weight of NO
x
emitted from an engine when a vehicle, e.g., motorcar, is allowed to run on an actual road surface (JP-A-11-23016). The method of measuring the weight of NO
x
according to this patent application has a system in which the flow rate of exhaust gas is determined using an intake air flow meter or an exhaust gas flow meter while measuring the concentration of NO
x
using a NO
x
analyzer to determine the weight of NO
x
emitted from an engine on the basis of the above NO
x
concentration and flow rate of exhaust gas in a simple manner.
However, since the flow rate of exhaust gas is determined using an intake air flow meter or an exhaust gas flow meter in the method of measuring the weight of NO
x
in the aforementioned patent application, the flow meter must be calibrated to determine the flow measurement. Also, pressure drop affords possibility for producing errors in the values measured of the exhaust gas flow rate and the point in question is open to further improvement.
The present invention has been conducted taking the above situation into consideration and one of the objects is to provide a simple method of measuring NO
x
in a running vehicle (hereinafter simply referred to as “NO
x
simple measurement method”). The method ensures that the weight of NO
x
emitted from the engine, while running the vehicle on an actual road surface, can be determined more simply and accurately.
SUMMARY OF THE INVENTION
The above object is attained by a NO
x
simple measurement method in accordance with the present invention. The method comprises mounting a NO
x
analyzer, an air-fuel ratio sensor, and a data collection device on a vehicle, allowing, the vehicle to run on an actual road surface, introducing the exhaust gas emitted from an engine to the NO
x
analyzer in order to determine the concentration of NO
x
contained in the exhaust gas, determining the flow rate of the exhaust gas by using the fuel injection quantity based on the fuel injection pulse output from an electronic control unit mounted on the vehicle and the output of the air-fuel ratio sensor, and determining the weight of NO
x
emitted from the engine from the flow rate of the exhaust gas and the concentration of NO
x
.
In the NO
x
simple measurement method of the present invention, a vehicle is allowed to run on an actual road surface at varying speeds and gear ratios to thereby apply a proper load to the vehicle, and NO
x
is generated under the load. The concentration of NO
x
is then measured by a NO
x
analyzer mounted on the vehicle. On the other hand, the flow rate of the exhaust gas is found using the fuel injection quantity based on the fuel injection pulse output from an electronic control unit mounted on the vehicle and the output of the air-fuel ratio sensor. Accordingly, a given calculation is made using the flow rate of the exhaust gas and the concentration of NO
x
wherein the weight of NO
x
emitted from an engine can be found. Thus, the weight of NO
x
generated from an engine running on an actual road surface can be measured in real time.
When a direct insertion type NO
x
analyzer is used as the aforementioned NO
x
analyzer and is attached to an exhaust pipe connected to an engine, the structure of a measurement system is made simple.


REFERENCES:
patent: 6230487 (2001-05-01), Blumenstock et al.
patent: 11-023016 (1999-01-01), None

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