Measuring and testing – Sampler – sample handling – etc. – With heating or cooling
Reexamination Certificate
1999-05-12
2001-09-25
Raevis, Robert (Department: 2856)
Measuring and testing
Sampler, sample handling, etc.
With heating or cooling
Reexamination Certificate
active
06293161
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an exhaust gas sampling apparatus for analyzing contents in exhaust gas from an automobile, a motorboat, a mowing machine and so on.
2. Description of Related Art
The construction of an exhaust gas sampling apparatus according to the conventional art will be explained by referring to FIG.
8
. In the figure, reference numeral
201
indicates an intake air supply conduit for supplying fresh air from outside, an end of which is enlarged in the diameter thereof so as to form an air intake
202
, in which is provided a filter
203
. To the intake air supply conduit
201
is connected an exhaust gas supply conduit
204
, and a gas mixture circulation conduit
205
is formed downstream from the connecting portion of the intake air supply conduit
201
and the exhaust gas supply conduit
204
, and through the gas mixture circulation conduit
205
, exhaust gas diluted with fresh air is extracted to the downstream side by a blower
206
provided in the downstream side thereof.
Here, the reason for mixing the exhaust gas with fresh air from outside when analyzing the contents of the above-mentioned exhaust gas lies in that there is a necessity to lower a ratio of moisture within the exhaust gas by mixing with fresh air, since otherwise dew drops will be condensed due to a decrease in the temperature on the way, when trying to send a pure sample of exhaust gas to an analyzer.
Interrupting the gas mixture circulation conduit
205
in the down-stream side from the connecting portion of the above-mentioned intake air supply conduit
201
and exhaust gas supply conduit
204
, there is provided a mixing device
207
, and further provided is a venturi device
208
down-stream of the mixing device
207
, for the purpose of maintaining the exhaust gas at a constant flow rate, as a means of conforming to the different displacements and exhaust flow rates of various kinds of engines.
Further, from the gas mixture circulation conduit
205
is divided a sampling conduit
209
, in the downstream side from the above-mentioned mixing device
207
but up-stream from the above-mentioned venturi device
208
, and this sampling conduit
209
is further divided into three (
3
) conduits, to each of which is connected one of sampling bags
211
. . . through one of joints
210
. . . , respectively.
Further, from the air supply conduit
201
leads a reference air supply conduit
220
, from the flow up-stream from the connecting portion with the exhaust gas supply conduit
204
, and this reference air supply conduit
220
is also divided into three (
3
) conduits to be connected to the sampling bags
211
. . . through one of the joints
210
. . . , respectively.
Furthermore, a lead back conduit
230
being connected to the analyzer is connected to or closed from each one of the divided conduits
209
a and
220
a by means of valves
230
a
. . . while an exhaust conduit
240
is also connected to or closed from each one of the divided conduits
209
a
and
220
a
by means of valves
240
a
, respectively. Still, valves
212
and
222
are provided in the up-stream side from the valves
230
a
and
240
a
for each one of the divided conduits
209
a
and
220
a
, and also a reversible pump
241
is provided in the flow of the exhaust conduit
240
.
Moreover, an air supply conduit
242
is connected or joint to the above-mentioned gas mixture circulation conduit
205
just before (up-stream of) the blower
206
provided thereon.
The analyzing method in such an exhaust gas sampling apparatus according to the conventional art, the structure of which is mentioned in the above, will be described below, in particular with reference to the sampling conduit
209
.
First, the pump is driven under the condition where the valves
212
are turned OPEN while the valves
230
a
and
240
a
are CLOSED, so as to introduce the diluted exhaust gas into each of the sampling bags
211
according to a measuring mode, and then the valves
212
and
240
a
are turned CLOSED while the valves
230
a
are OPEN, so as to send the diluted exhaust gas into the analyzer through the lead back conduit
230
, thereby measuring carbon monoxide (CO), hydrocarbon (HC), nitrogen compounds (NO
x
) and so on in the exhaust gas, in accordance with the predetermined mode for measuring.
As such the measuring modes are already known as an LA-4 mode and a US06 mode, as per the regulations in the USA, for example. (There are also known a 10.15 mode and 11 mode, as per the domestic regulations in Japan.) Here, in accordance with the LA-4 mode, the contents in the exhaust gas are measured in each of the following time periods: (1) from starting of the engine up to a time point of a lapse of 504 sec., (2) from 505 seconds up to the time point of the lapse of 1,374 sec., and (3) from a re-starting after
10
minutes suspension of the engine up to the time point of the lapse of 504 sec. Accordingly, in the LA-4 mode, the exhaust gases during the above-mentioned intervals (1) to (3) must be collected into the sampling bags, respectively, and therefore there are prepared the three (3) pieces of the divided conduits and the three (3) bags.
Also, in accordance with the SU
06
mode, in which the exhaust gas exhausted from the engine being at almost full throttle for ten (10) minus is reserved or stored in the sampling bag to be analyzed, only one of the sampling bags is used according to this measuring mode.
In the case where the measurement of the above LA-4 mode is conducted with an ordinary gasoline engine, the flow rate is changed for each of the intervals (1) to (3) of the LA-4 mode, while suppressing the mixture with air to as low a ratio as possible, for obtaining correct measurement values. Therefore, because the gas mixture flowing within the gas mixture circulation conduit must be controlled to be from 3 to 9 m
3
/min in the flow rate thereof, the above-mentioned venturi, of a variable flow rate type, is utilized.
Further, in the US06 mode, the gas mixture must be controlled at 21 m
3
/min in the flow rate thereof.
FIG.
9
(
a
) shows an enlarged cross sectional view taken along the direction of the flow in the venturi
208
of the variable flow rate type, and FIG.
9
(
b
) shows an enlarged cross sectional view taken in the direction orthogonal to the direction of flow, wherein the cross sectional area of flow passage
252
at a neck portion
251
is changed by shifting an external wall or a core of the venturi in a relative manner, so as to control the flow rate through it.
When completing the measurement, the valves
212
and
230
a
are turned CLOSED while the valves
240
a
are OPEN, and air is sent into the sampling bags
211
by driving the reversible pump
241
of the exhaust conduit
240
into the reverse direction of rotation. Then, the reversible pump
241
is rotated in the forward direction to discharge the exhaust gas including the air within the sampling bag. The exhaust gas within the sampling bag is completely removed by repeating this operation, so as to be prepared for the next measurement.
In the exhaust gas sampling apparatus as mentioned above, an exhaust pipe of an automobile is connected to the exhaust gas supply conduit
204
and at the same time the blower
206
is driven, then the exhaust gas is diluted by mixing with the intake air, to a concentration wherein the mixture has a mass 20 times that of the exhaust gas constituent therein, so as to eliminate the condensation of water droplets due to the decrease in the temperature of the gas. After being sent through the sampling conduit
209
, as well as the conduit divided therefrom, to be then stored in the bag
211
, a portion of the exhaust gas is supplied to the analyzer to be analyzed.
However, when the exhaust gas exhausted from the engine is diluted to 20 times the mass thereof, it is difficult to obtain a correct result of the measurements. In particular, with an automobile of low pollution (emissions) installed with a lean burn gasoline engine which burns diluted fuel therein, the conte
Hanashiro Noriyuki
Matsuyama Mamoru
Obara Keisuki
Sasaki Kyoshuke
Shibata Atsushi
Birch & Stewart Kolasch & Birch, LLP
Honda Giken Kogyo Kabushiki Kaisha
Raevis Robert
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