Technical Field
[0001]
The present invention relates to an exhaust gas analysis apparatus and the
like for analyzing a measurement target material contained in exhaust gas.
Background Art
[0002]
As this sort of exhaust gas analysis apparatus, as disclosed in Patent
Literature 1, there is one that dilutes the exhaust gas of an internal combustion
10 engine at a predetermined dilution ratio to introduce the diluted exhaust gas to a
filter, and measures the mass of particulate matter (hereinafter also referred to as
PM) in the diluted exhaust gas collected by the filter.
[0003]
Meanwhile, in a PM measurement test of recent years, it is legislated to
15 weight measurement results in accordance with a vehicle driving mode, and for
example, CFR 1066 stipulates that a measurement result in Phase 1 is weighted by
a factor of 0.43, that in Phase 2 by 1, and that in Phase 3 by 0.57.
[0004]
Methods for such weighting include one that calculates the mass of PM
20 by measuring the mass of PM using one filter for each of the phase intervals, and
multiplying the resulting measured values by corresponding ones of the
above-described weighting factors to take a weighted average. However, there is
a problem that filter replacement work between adjacent phase intervals is
time-consuming, and therefore PM measurement becomes troublesome. In
25 addition, in recent years, since PM concentration in exhaust gas has been reduced,
3
the amount of PM collected by a filter used during each phase interval has been
extremely small, and therefore it has been difficult to accurately measure the mass
of PM.
Citation List
Patent Literature5 s
[0005]
Patent Literature 1: Japanese Unexamined Patent Application Publication
No. 2003-50194
10 Summary of Invention
Technical Problem
[0006]
The present invention has been made in consideration of the problems as
described above, and intends to provide an exhaust gas analysis apparatus that,
15 without replacing a filter in accordance with a driving mode, can accurately
measure particulate matter.
Solution to Problem
[0007]
20 That is, the exhaust gas analysis apparatus according to the present
invention includes: a collection part that collects a measurement target component
in sampling exhaust gas partially or wholly splitting from original exhaust gas: a
diluent gas supply path through which diluent gas flows; and a split flow ratio
control mechanism configured to, during a test of a vehicle or a part of the vehicle,
25 change a split flow ratio that is the ratio of the split flow rate of the sampling
4
exhaust gas to a total flow rate of the original exhaust gas.
[0008]
Note that the original exhaust gas is a concept including raw exhaust gas
discharged from an engine or exhaust gas resulting from diluting the raw exhaust
gas with diluent ga5 s.
[0009]
Such an exhaust gas analysis apparatus can weight the flow rate of the
sampling exhaust gas flowing to the collection part, and therefore without the
need to replace the collection part, can continue to be used as a test proceeds.
10 Accordingly, even when the amount of particulate matter discharged from the
vehicle is small, the particulate matter can be collected by the collection part to
analyze it with the mass of it being enough to ensure detection accuracy.
[0010]
Specific embodiments for performing a test reflecting weighting factors
15 stipulated in regulations or the like include one in which the split flow ratio
control mechanism is configured to change the split flow ratio in accordance with
a vehicle driving mode set in compliance with a predetermined regulation.
[0011]
In order to allow the collection part to collect a minimum amount of PM
20 detectable by a detector, and accurately perform analysis even when the
concentration of PM contained in exhaust gas is very low, it is only necessary that
in multiple phase intervals constituting a driving mode, the sampling exhaust gas
is adapted to flow to the collection part in common.
[0012]
25 Specific examples to enable the reflection of weighting corresponding to
5
respective test contents stipulated in predetermined regulations include one in
which the driving mode is constituted by multiple phase intervals, weighting
factors are set for the respective phase intervals, and the split flow ratio control
mechanism is configured to change the split flow ratio in dependence on the
weighting factors set for the respective phase intervals5 .
[0013]
In the predetermined regulations, some of the contents of a vehicle
running test may be allowed to be integrated or omitted, for example, when cold
starting a vehicle and when hot starting the vehicle. In order to make it possible
10 to change the split flow ratio in dependence of corresponding weighting factors
even in the case of such modified test contents, it is only necessary that the
driving mode is constituted by: a cold start region that is constituted by one or
more phase intervals and in which the vehicle is cold started; and a hot start
region that is constituted by one or more phase intervals and in which the vehicle
15 is hot started, weighting factors are respectively set for the cold start region and
the hot start region, and the split flow ratio control mechanism is configured to
change the split flow ratio in dependence of the weighting factors set for the cold
start region and the hot start region.
[0014]
20 Specific examples adapted to observe regulations stipulating a PM
measurement test and the like, change a dilution ratio, and obtain a highly reliable
analysis result include one in which the cold start region is constituted by a first
phase interval and a second phase interval, the hot start region is constituted by a
third phase interval, a ratio among weighting factors respectively for the first
25 phase interval, the second phase interval, and the third phase interval is set to
6
a:1:(1 – a), and the split flow ratio control mechanism is configured to change the
split flow ratio among the respective phase intervals so that a ratio among split
flow ratios in the first phase interval, the second phase interval, and the third
phase interval becomes 1/a:1:1/(1 – a).
[5 0015]
In order to obtain a split flow ratio reflecting a weighting factor assigned
to each phase interval by changing the flow rate of the diluent gas, for example,
every time a phase interval changes, the exhaust gas analysis apparatus only has to
be one further including: a main flow path through which the original exhaust gas
10 flows; a sampling flow path through which the sampling exhaust gas partially
splitting from the original exhaust gas flows; and a diluted exhaust gas flow path
that is a flow path after merger of the sampling flow path and the diluent gas
supply path and through which diluted exhaust gas resulting from diluting the
sampling exhaust gas with the diluent gas flows.
15 [0016]
Specific control configurations for controlling the split flow ratio include
one in which the split flow ratio control mechanism includes: a main flowmeter
that measures the total flow rate of the original exhaust gas flowing through the
main flow path; a first flowmeter that measures the flow rate of the diluent gas
20 flowing through the diluent gas supply path; a flow rate control valve that is
provided in the diluent gas supply path; a second flowmeter that measures the
flow rate of the diluted exhaust gas flowing through the diluted exhaust gas flow
path; a split flow ratio setting part that sets a target split flow ratio in accordance
with a driving mode, a target flow rate calculation part that, on the basis of the
25 total flow rate of the original exhaust gas measured by the main flowmeter, the
7
target split flow ratio set by the split flow ratio setting part, and the measured flow
rate of the diluted exhaust gas measured by the second flowmeter, calculates the
target flow rate of the diluent gas flowing through the diluent gas supply path, and
a first controller that controls the flow rate control valve so that the deviation
between the measured flow rate of the diluent gas measured by the first flowme5 ter
and the target flow rate calculated by the target flow rate calculation part
decreases.
[0017]
In such a configuration, since it is not necessary to increase/decrease the
10 total flow rate of the exhaust gas flowing through the collection part, an error due
to flow rate response delay is less likely to occur, and analysis accuracy is easily
improved. Further, when changing the flow rate of the diluent gas in order to
change the split flow ratio, the flow rate can be changed before passing through
the collection part. Accordingly, as compared with when changing the total flow
15 rate of the diluted exhaust gas passing through the collection part, a dilution ratio
can be changed with good followability to changes in test conditions, and the flow
rate of the sampling exhaust gas in the diluted exhaust gas can be regulated to
have a value corresponding to a weighting factor or the like. For example, even
when a weighting factor changes from 0.43 to 1.00, the amount of the sampling
20 exhaust gas contained in the diluted exhaust gas can be quickly changed to an
amount corresponding to the changed weighting factor while keeping the total
flow rate of the diluted exhaust gas constant. Accordingly, an error due to
response delay of flow rate control can be prevented from occurring, for example,
when measuring the mass or the like of particulate matter.
25 [0018]
8
In addition, since the flow rate of the diluted exhaust gas whose flow rate
is larger than those of the diluent gas and sampling gas can be kept constant, for
example, the flowmeter for measuring the flow rate of the diluted exhaust gas is
not required to have a wide measurement range and high accuracy.
[5 0019]
In order to make it possible to, without directly controlling the flow rate
of the sampling exhaust gas, indirectly change the flow rate of the sampling
exhaust gas by controlling the flow rate of the diluent gas while keeping the total
flow rate of the diluted exhaust gas passing through the collection part constant, it
10 is only necessary that the split flow ratio control mechanism is one further
including: a pump provided in the diluted exhaust gas flow path; and a second
controller that controls the pump so that the flow rate of the diluted exhaust gas
flowing through the diluted exhaust gas flow path becomes constant at a
predetermined flow rate.
15 [0020]
An exhaust gas analysis system further including: the exhaust gas
analysis apparatus according to the present invention; and an analysis part that
analyzes the measurement target component collected by the collection part can
achieve accurate analysis because the analysis part can analyze the collected
20 measurement target component with weighting or the like stipulated in regulations
or the like reflected.
[0021]
An exhaust gas analysis method according to the present invention is one
using an exhaust gas analysis apparatus including a collection part that collects a
25 measurement target component in sampling exhaust gas partially or wholly
9
splitting from original exhaust gas, and the exhaust gas analysis method includes a
split flow ratio changing step of, during a test of a vehicle or a part of the vehicle,
changing a split flow ratio that is the ratio of a split flow rate of the sampling
exhaust gas to a total flow rate of the original exhaust gas.
[5 0022]
Such an exhaust gas analysis method enables the same effects as those of
the above-described exhaust gas analysis apparatus to be obtained.
[0023]
Also, a program recording medium recorded with a program for an
10 exhaust gas analysis apparatus according to the present invention is characterized
in that the program is used for the exhaust gas analysis apparatus including a
collection part that collects a measurement target component in sampling exhaust
gas partially or wholly splitting from original exhaust gas, and instructs a
computer to fulfill a function as a split flow ratio control part that, in accordance
15 with a vehicle driving mode set in compliance with a predetermined regulation,
changes a split flow ratio that is the ratio of the split flow rate of the sampling
exhaust gas to the total flow rate of the original exhaust gas.
[0024]
When installing such a program for an exhaust gas analysis apparatus in
20 an existing exhaust gas analysis apparatus, while keeping the flow rate of diluted
exhaust gas passing through a filter constant as with the above-described exhaust
gas analysis apparatus, a dilution ratio can be changed, and the occurrence of a
measurement error due to control delay can be reduced. Note that the program
may be one electronically delivered or recorded on a program recording medium
25 such as a CD, DVD, or flash memory.
10
[0025]
A calibration method for an exhaust gas analysis apparatus according to
the present invention is a calibration method for an exhaust gas analysis apparatus
including: a diluted exhaust gas flow path through which diluted exhaust gas
resulting from, with diluent gas, diluting sampling exhaust gas partially or wholl5 y
splitting from original exhaust gas flows; a collection part that is provided in the
diluted exhaust gas flow path and collects particulate matter in the diluted exhaust
gas; a bypass flow path that, in the diluted exhaust gas flow path, branches from
the upstream side of the collection part and merges with the downstream side of
10 the collection part; a second flowmeter that is provided on the downstream side of
the merging point of the bypass flow path in the diluted exhaust gas flow path and
measures a flow rate through the diluted exhaust gas flow path; and a bypass flow
rate control mechanism that controls the bypass flow rate of the diluted exhaust
gas flowing through the bypass flow path. In addition, the bypass flow rate
15 control mechanism includes a bypass flowmeter that measures the bypass flow
rate of the diluted exhaust gas flowing through the bypass flow path. Further,
the calibration method includes: a closing step of closing an inflow path to the
filter; and calibrating the bypass flowmeter with the second flowmeter as a
reference flowmeter and the bypass flow meter as a flowmeter to be calibrated.
20 [0026]
Such a calibration method enables the second flowmeter that measures
the total flow rate of the diluted exhaust gas and the bypass flowmeter that
measures the bypass flow rate of the diluted exhaust gas flowing through the
bypass flow path to be set to have substantially the same sensor characteristics.
25 For this reason, even when the second flowmeter has an error relative to an actual
11
flow rate, the bypass ratio of the diluted exhaust gas can be accurately kept, and
the accuracy of measuring PM or the like can be highly accurately kept.
Advantageous Effects of Invention
[5 0027]
According to the present invention configured as described above,
weighting corresponding to a driving mode can be achieved by changing the split
flow ratio, and regardless of a change in driving mode, the mass or the like of PM
can be accurately measured using the single collection part without error while
10 observing regulations. Also, the variation range of the flow rate of the diluted
exhaust gas passing through the collection part can be decreased, and therefore in
order to measure the flow rate, a flowmeter having a wide measurement range and
high resolution does not have to be used. Accordingly, the exhaust gas analysis
apparatus can be configured to be a simple and inexpensive one.
15
Brief Description of Drawings
[0028]
FIG. 1 is a schematic diagram illustrating an exhaust gas analysis
apparatus according to a first embodiment of the present invention and a vehicle
20 running test system;
FIG. 2 is a schematic diagram illustrating the exhaust gas analysis
apparatus according to the first embodiment;
FIG. 3 is a functional block diagram illustrating the configuration of a
split flow ratio control mechanism in the first embodiment;
25 FIG. 4 is a schematic diagram illustrating an example of test conditions in
12
the first embodiment;
FIG. 5 is a flowchart illustrating a procedure for analyzing particulate
matter using the exhaust gas analysis apparatus in the first embodiment;
FIG. 6 is a schematic diagram illustrating an exhaust gas analysis
apparatus according to a second embodiment of the present invention5 ;
FIG. 7 is a functional block diagram illustrating the configuration of a
split flow rate control mechanism in the second embodiment;
FIG. 8 is a schematic diagram illustrating an example of test conditions in
the second embodiment;
10 FIG. 9 is a flowchart illustrating a procedure for analyzing particulate
matter using the exhaust gas analysis apparatus in the second embodiment;
FIG. 10 is a flowchart illustrating a calibration procedure for the exhaust
gas analysis apparatus in the second embodiment; and
FIG. 11 is a schematic diagram illustrating an exhaust gas analysis
15 apparatus according to a third embodiment of the present invention.
Description of Embodiments
[0029]
A first embodiment of the exhaust gas analysis apparatus according to the
20 present invention will be described below.
[0030]
An exhaust gas analysis apparatus 100 of the first embodiment is one that
measures particulate matter (hereinafter also referred to as PM) contained in the
exhaust gas of an internal combustion engine as a measurement target component,
25 and in a vehicle running test system 200, used to measure PM discharged from an
13
engine of a vehicle VH in running. In the vehicle running test system 200, the
exhaust gas analysis apparatus 100 is configured to sample part of exhaust gas
discharged from the engine as an internal combustion engine, and after dilution,
introduce the total amount of the diluted exhaust gas to a filter F.
[5 0031]
The vehicle running test system 200 is one that performs a running test of
a vehicle in a driving mode stipulated in predetermined regulations in a chamber
called a cell, and performs exhaust gas analysis, fuel consumption measurement,
and the like during the running test. As illustrated in the overall configuration in
10 FIG. 1, the vehicle running test system 200 includes a measurement chamber and
a test chamber that are mutually airtightly divided. In the test chamber, a chassis
dynamometer SD and the exhaust gas analysis apparatus 100 are arranged. In
the measurement chamber, equipment such as a management apparatus (not
illustrated) for managing various types of measurement and the like is arranged.
15 [0032]
The chassis dynamometer SD is, for example, a uniaxial one, and
includes: a dynamometer main body having a rotating drum to be mounted with
the drive wheels of the vehicle VH, and the like; and a dynamometer control
device that controls the drum to give a running load similar to that on a road to the
20 vehicle VH. The dynamometer control device SD is configured using, for
example, a computer including a CPU, a memory, and the like, and has a function
capable of mutually communicating a control signal, data, and the like with the
outside. Further, it goes without saying that although FIG. 1 illustrates the
chassis dynamometer for 2WD and FF vehicles, the chassis dynamometer may be
25 one having paired rotating drums at the front and back to be able to respond to
14
4WD vehicles, or a biaxial one.
[0033]
In addition, in the first embodiment, the exhaust gas analysis apparatus
100 is fixed in the test chamber in order to perform the exhaust gas analysis of the
vehicle VH running on the chassis dynamometer SD. However, the exhaust ga5 s
analysis apparatus 100 can also be mounted in a vehicle running on a road, and in
doing so, can also measure PM contained in exhaust gas discharged from an
internal combustion engine during an actual on-road run.
[0034]
10 Specifically, as illustrated in FIG. 2, the exhaust gas analysis apparatus
100 is one including: a main flow path ML through which original exhaust gas as
exhaust gas discharged from the internal combustion engine flows; a sampling
flow path L1 through which sampling exhaust gas into which the original exhaust
gas flowing through the main flow path ML is partially split flows; a diluent gas
15 supply path L2 through which diluent gas for diluting the sampling exhaust gas
flows; a dilution tunnel 10 connected with the sampling flow path L1 and the
diluent gas supply path L2; a diluted exhaust gas flow path L3 through which
diluted exhaust gas produced in the dilution tunnel 10 flows; and a split flow ratio
control mechanism 20 configured to, depending on test conditions to be set,
20 change a split flow ratio that is the ratio between the total flow rate of the original
exhaust gas and the split flow rate of the sampling exhaust gas.
[0035]
The sampling flow path L1 is one for, from the main flow path ML
connected to a tail pipe of the vehicle VH, splitting the exhaust gas discharged
25 from the internal combustion engine to sample part of the exhaust gas, and
15
introducing the sampled exhaust gas to the diluted exhaust gas flow path L3
through the dilution tunnel 10. That is, the first embodiment is configured to
split the original exhaust gas as the raw exhaust gas flowing through the main
flow path ML at a predetermined ratio and flow the part of the original exhaust
gas through the sampling flow path L5 1.
[0036]
The diluent gas supply path L2 is one for introducing the diluent gas to
the dilution tunnel 10, whose one end is connected to an unillustrated diluent gas
source and whose other end is connected to the dilution tunnel 10. That is, the
10 diluent gas supply path L2 is one for supplying the diluent gas to the diluted
exhaust gas flow path L3 through the dilution tunnel 10. In addition, in the first
embodiment, the diluent gas is air.
[0037]
The dilution tunnel 10 is one for diluting the exhaust gas at a
15 predetermined dilution ratio to produce the diluted exhaust gas, and here a
so-called micro-tunnel. Note that the dilution tunnel 10 may be a so-called
full-tunnel to be introduced with the total amount of the exhaust gas discharged
from the internal combustion engine.
[0038]
20 The diluted exhaust gas flow path L3 is one whose start point is
connected to the dilution tunnel 10 and through which the diluted exhaust gas
flows. The diluted exhaust flow path L3 is provided with, for example, one
sheet of filter F as a collection part, and configured so that the filter F collects PM
contained in the diluted exhaust gas. In addition, the end point of the diluted
25 exhaust gas flow path L3 may be opened to the atmosphere or connected to
16
various exhaust gas analyzers. Note that the filter F is not replaced even when
the below-described phase interval in the driving mode is changed, but
continuously used.
[0039]
The split flow ratio control mechanism 20 is one that controls the 5 flow
rates of the above-described diluent gas and diluted exhaust gas, and thereby
controls the split flow ratio that is the ratio of the split flow rate of the sampling
exhaust gas to the total flow rate of the original exhaust gas. That is, given that
the total flow rate of the original exhaust gas is denoted by QM and the split flow
10 rate of the sampling exhaust gas is denoted by Qd, the split flow ratio r has a value
represented by r = QM / Qd. In addition, when the split flow ratio is changed, the
dilution ratio applied of the diluted exhaust gas passing through the filter F is also
changed. Here, the dilution ratio is the ratio between the split flow rate of the
sampling exhaust gas and the flow rate of the diluent gas.
15 [0040]
The split flow ratio control mechanism 20 includes: a main flowmeter
MFM provided in the main flow path ML; a first flowmeter FM1 and a flow rate
control valve V provided in the diluent gas supply path L2; a second flowmeter
FM2 and suction pump P (e.g., a Roots blower) whose suction capability can be
20 changed by rotation speed control, which are provided on the downstream side of
the filter F in the diluted exhaust gas flow path L3; and a control device 22 for
controlling the flow rate control valve V and the suction pump P. Note that the
first flowmeter FM1 and the second flowmeter FM2 in the first embodiment are
both venturi flowmeters.
25 [0041]
17
The control device 22 is one physically including a CPU, a memory, an
A/D converter, a D/A converter, and the like. In addition, the CPU and its
peripheral devices cooperate in accordance with a program stored in a
predetermined area of the memory, and thereby the control device 22 functions so
as to acquire flow rate signals indicating the measured values of the respecti5 ve
flowmeters FM1 and FM2, as well as control the flow rate control valve V and the
suction pump P on the basis of the flow rate signals.
[0042]
Specifically, as illustrated in FIG. 3, the control device 22 fulfills
10 functions as at least a split flow ratio setting part 23, a weighting factor storage
part 24, a target flow rate calculation part 25, a first controller 26, and a second
controller 27. The functions of the respective parts will be described below.
[0043]
When an operator provides a test start input or the like, the split flow
15 ratio setting part 23 refers to the weighting factor storage part 24 to set target split
flow ratios based on weighting factors determined depending on the contents of
the test in the target flow rate calculation part 25. In the first embodiment, target
split flow ratios corresponding to the below-described respective phase intervals
in the driving mode are set in the target flow rate calculation part 25.
20 [0044]
The weighting factor storage part 24 stores test condition data indicating
the test conditions and corresponding split flow ratio data. Here, the test
conditions refer to test conditions stipulated in predetermined regulations such as
regulations or exhaust gas measurement regulations, test conditions arbitrarily set
25 by an operator, or such other test conditions. As the test conditions, the driving
18
mode stipulating, for example, what speeds the vehicle VH should be operated at
on the chassis dynamometer SD is stored in the weighting factor storage part 24.
Also, weighting factors for weighting test results in the respective phase intervals
constituting the driving mode are stored in the weighting factor storage part 24.
The driving mode and the weighting factors are stipulated in, for example5 ,
regulations (such as CFR 1066) as the predetermined regulations.
[0045]
That is, the weighting factor storage part 24 stores the driving mode as
illustrated in FIG. 4 and the weighting factors predetermined corresponding to the
10 respective phase intervals constituting the driving mode as the test condition data.
In the first embodiment, as the test condition data, the driving mode constituted by
the four phase intervals is stored, and the vehicle VH is driven so as to achieve
vehicle speeds as illustrated in the graph of FIG. 4, and the particulate matter in
the exhaust gas discharged from the internal combustion engine during the driving
15 is evaluated and analyzed.
[0046]
The driving mode is constituted by the four phase intervals, i.e., Phases 1
to 4. That is, the first half of the driving mode corresponds to a cold state region
based on a cold start, in which the vehicle is started from a state of being not
20 sufficiently warmed up, and is constituted by Phase 1 corresponding to the first
half in which variations in vehicle speed are large and Phase 2 corresponding to
the second half in which variations in vehicle speed are small as compared with
Phase 1.
[0047]
25 On the other hand, the second half of the driving mode corresponds to a
19
hot start region based on a hot start, in which the vehicle is started from a state of
being warmed up, and is constituted by Phase 3 corresponding to the first half in
which variations in vehicle speed is large and Phase 4 corresponding to the second
half in which variations in vehicle speed is small as compared with Phase 3.
[5 0048]
In the first embodiment, a weighting factor is not set for each phase, but
collectively set for each of the cold and hot start regions each constituted by the
multiple phases. That is, the weighting factors for the cold and hot start regions
are stipulated by the regulations so as to meet, for example, a:(1 – a). In the first
10 embodiment, the weighting factor for the cold start region is set to 43 %, and that
for the hot start region is set to 57 %.
[0049]
In the first embodiment, the split flow ratio setting part 23 acquires the
weighting factors set for the cold and hot start regions from the weighting factor
15 storage part 24, and sets the target split flow ratios in the target flow rate
calculation part 25 so that 1/a:1/(1 – a) as the inverse ratio between the weighting
factors when performing the test in the respective regions can be obtained. In
the first embodiment, the split flow ratio setting part 23 sets the target split flow
ratios in the target flow rate calculation part 25 using, for example, the inverses of
20 the weighting factors stipulated in the predetermined regulations so that the
relationship of [a split flow ratio in the cold start region: a split ratio in the hot
start region = 2.32:1.75] can be obtained. Note that as a split flow ratio, for
example, a predetermined stipulated split flow ratio R is set, and the values of the
split flow ratios to be set are 2.32R for the cold start region, and 1.75R for the hot
25 start region. When such target split flow ratios are obtained, the flow rate of the
20
sampling exhaust gas passing through the filter F becomes one reflecting a
weighting factor stipulated by the predetermined regulations for each of the
regions.
[0050]
As illustrated in FIG. 3, the target flow rate calculation part 25 calculate5 s
the target flow rate of the diluent gas flowing through the diluent gas supply path
L2 necessary to obtain each of the target split flow ratios set by the split flow ratio
setting part 23. More specifically, on the basis of each of the target split flow
ratios set by the split flow ratio setting part 23, the total flow rate of the original
10 exhaust gas measured by the main flowmeter MFM, and the flow rate of the
diluted exhaust gas flowing through the diluted exhaust gas flow path L3
measured by the second flowmeter FM2, the target flow rate calculation part 25
calculates, as the target flow rate, the flow rate of the diluent gas to be flowed
through the diluent gas supply path L2. First, the target flow rate calculation part
15 25 divides the total flow rate of the original exhaust gas by the target split flow
ratio to thereby calculate the split flow rate of the sampling exhaust gas to be
obtained.
[0051]
That is, in the cold start region, the split flow rate of the sampling
20 exhaust gas to be obtained has a value resulting from dividing the total flow rate
of the original exhaust gas by 2.32R (value resulting from multiplying the total
flow rate of the original exhaust gas by 0.43/R), whereas in the hot start region,
the split flow rate of the sampling exhaust gas to be obtained has a value resulting
from dividing the total flow rate of the original exhaust gas by 1.75R (value
25 resulting from multiplying the total flow rate of the original exhaust gas by
21
0.57/R).
[0052]
In addition, the target flow rate calculation part 25 may calculate, as the
target flow rate of the diluent gas to be flowed through the diluent gas supply path
L2, a differential flow rate resulting from subtracting the split flow rate of 5 the
sampling exhaust gas to be obtained from the current measured flow rate of the
diluted exhaust gas being measured by the second flowmeter FM2.
[0053]
Further, the target flow rate of the diluent gas is set in the first controller
10 26. In addition, the target flow rate calculation part 25 also sets the total flow
rate (target flow rate) of the diluted exhaust gas to be flowed through the diluted
exhaust gas flow path L3 in the second controller 27 in accordance with test
settings.
[0054]
15 The first controller 26 performs flow rate feedback control of the flow
rate control valve V so that the deviations between the target flow rate of the
diluent gas calculated by the target flow rate calculation part 25 and the measured
flow rate of the diluent gas measured by the first flowmeter FM1 decreases.
Note that the target flow rate calculation part 25 updates the target flow rate of the
20 diluent gas on a control period basis. Accordingly, even when the flow rate of
the original exhaust gas discharged from the internal combustion engine changes,
the flow rate of the diluent gas is changed and thereby the specific split flow ratio
can be kept constant in each of the cold start region and the hot start region.
[0055]
25 The second controller 27 is one that controls an operation state of the
22
pump P, and in the first embodiment, performs the control so that the flow rate of
the diluted exhaust gas flowing through the diluted exhaust gas flow path L3
becomes constant at the total target flow rate of the diluted exhaust gas set by the
target flow rate calculation part 25. The total target flow rate of the diluted
exhaust gas set in the second controller 27 is not one successively updated 5 ted but
kept constant at the value set by the target flow rate calculation part 25.
[0056]
When viewed from the tunnel 10, the flow rate of the diluent gas as one
input and the flow rate of the diluted exhaust gas as an output are controlled, and
10 therefore the flow rate of the exhaust gas flowing through the sampling flow path
L1 as the other input is ideally kept at the differential flow rate between the flow
rate of the diluted exhaust gas and the flow rate of the diluent gas.
[0057]
A procedure for analyzing particulate matter by the exhaust gas analysis
15 apparatus of the first embodiment configured as described above will be described
with reference to a flowchart of FIG. 5.
[0058]
First, regarding what kind of test is performed, an operator sets the test
conditions in the control device 22 (Step S1).
20 [0059]
Then, the split flow ratio setting part 23 acquires the test condition data
and the weighting factors from the weighting factor storage part 24, and in the
target flow rate calculation part 25, sets the target split flow ratios corresponding
to the weighting factors set for the respective regions in the driving mode of the
25 test to be performed (Step S2).
23
[0060]
That is, the first controller 26 controls the flow rate control valve V so as
to obtain 2.32R as the target split flow ratio corresponding to the weighting factor
set for the cold start region. Specifically, the flow rate feedback control adapted
to set, as the target flow rate of the diluent gas, a flow rate obtained by subtracti5 ng
a value resulting from dividing the current total flow rate of the original exhaust
gas measured by the main flowmeter MFM by 2.32R from the current measured
flow rate of the diluted exhaust gas measured by the second flowmeter FM2 is
continued (Step S3).
10 [0061]
Further, the test proceeds, and before performing the test in the hot start
region, the split flow ratio setting part changes the target split flow ratio to 1.75R
that is a value corresponding to the hot start region. The first controller 26
controls the flow rate control valve V so as to obtain the target flow rate of the
15 diluent gas corresponding to the changed target split flow ratio. Specifically, the
flow rate feedback control adapted to set, as the target flow rate of the diluent gas,
a flow rate obtained by subtracting a value resulting from dividing the current
total flow rate of the original exhaust gas measured by the main flowmeter MFM
by 1.75R from the current measured flow rate of the diluted exhaust gas measured
20 by the second flowmeter FM2 is continued (Step S4).
[0062]
Note that in Steps S3 and S4, the second controller 27 continues the
control so that the flow rate of the diluted exhaust gas is kept constant by the
pump P. Also, the diluted exhaust gas passes through the filter F common to
25 both Steps S3 and S4.
24
[0063]
When the test in the cold and hot start regions is finished, the filter F is
detached, and the amount of collected PM and the like are analyzed by an analysis
part (Step S5).
[5 0064]
On the basis of a result obtained in Step S5, the amount of PM contained
in the exhaust gas discharged from the internal combustion engine is calculated
(Step S6).
[0065]
10 The exhaust gas analysis apparatus 100 of the first embodiment
configured as described above can reflect the weighting factors set for the
respective regions by, without changing the flow rate of the diluted exhaust gas
passing through the filter F, changing the flow rate of the diluent gas in
accordance with the driving mode stipulated in the predetermined regulations to
15 change the split flow ratio, and increasing/decreasing the amount of the exhaust
gas in the diluted exhaust gas passing through the filter F. Accordingly, it is not
necessary to replace the filter when the driving mode of the vehicle VH changes
from the cold start region to the hot start region, and therefore time and effort
necessary for the replacement and the like can be omitted. Also, even when the
20 amount of the particulate matter discharged from the internal combustion engine
is small, an amount enough to ensure measurement accuracy can be collected by
the filter F for the analysis.
[0066]
In addition, since it is not necessary to increase/decrease the total flow
25 rate of the diluted exhaust gas passing through the filter F, an error due to
25
response delay is less likely to occur.
[0067]
Further, before passing through the filter F, the flow rate can be changed,
and therefore as compared with when changing the total flow rate of the diluted
exhaust gas passing through the filter F, followability is good. Accordingly5 ,
when the test switches from the cold start region to the hot start region, the flow
rate of the exhaust gas in the diluted exhaust gas can be changed to have a value
corresponding to the weighting factor and the like set for each of the driving
mode.
10 [0068]
Still further, since the flow rate of the diluted exhaust gas whose flow rate
is larger than those of the diluent gas and exhaust gas is kept constant by the pump
P, for example, the second flowmeter FM2 for measuring the flow rate of the
diluted exhaust gas is not required to be one having a wide range and high
15 accuracy.
[0069]
In addition, since the exhaust gas analysis apparatus 100 of the first
embodiment can be mounted in a vehicle running on a road, an actual on-road test
can be performed in compliance with regulations in one run without replacing the
20 filter F.
[0070]
Variations of the first embodiment will be described. As the
configuration of the driving mode, weighting factors, split flow ratios are not
limited to those described above, but can be variously changed. For example,
25 the driving mode may be constituted by Phases 1 to 3, in which the ratio among
26
weighting factors set for the respective phase intervals meets the relationship of [a
weighting factor in Phase 1 : a weighting factor in Phase 2 : a weighting factor in
Phase 3 = 0.43:1 :0.57]. In this case, the ratio among split flow ratios set for the
respective phase intervals may be the inverse ratio among the weighting factors.
Specifically, it is only necessary to be [a split flow ratio set for Phase 1 : a spli5 t
flow ratio set for Phase 2 : a split flow ratio set for Phase 3 = 2.32:1:1.75].
[0071]
Also, the driving mode may be one constituted by Phases 1 to 4, in which
weighting factors are set for the respective phase intervals. Specifically, it may
10 be possible to be [a weighting factor in Phase 1 : a weighting factor in Phase 2 : a
weighting factor in Phase 3 : a weighting factor in Phase 4 = 0.754:0.754:1:1].
In addition, in this case, it is only necessary that the ratio among split flow ratios
set for the respective phase intervals is 1.32:1.32:1:1.
[0072]
15 Next, a second embodiment of the present invention will be described
with reference to FIGS. 6 to 9.
[0073]
As illustrated in FIG. 6, an exhaust gas analysis apparatus 100 of the
second embodiment is adapted to further include: a bypass flow path L4 that, in
20 the diluted exhaust gas flow path L3, branches from the upper stream of the filter
F and merges with the lower stream of the filter F; and a bypass flow rate control
part 30 that controls a bypass flow rate through the bypass flow path L4 while
flowing the diluted exhaust gas to the filter F.
[0074]
25 That is, the second embodiment is configured not to change the split flow
27
ratio so as to correspond to weighting in each driving mode, but to be able to
obtain the flow rate of the diluted exhaust gas passing through the filter F, which
corresponds to weighting in each driving mode, by increasing/decreasing the flow
rate of the diluted exhaust gas bypassed through the bypass flow path L4.
[5 0075]
The bypass flow path L4 is one for bypassing the filter F without flowing
part of the diluted exhaust gas through the filter F, and branches from a branching
point between the dilution tunnel 10 and the filter F and merges with a merging
point between the filter F and the suction pump P. Meanwhile, if the merging
10 point Y of the bypass flow path L4 is provided on the downstream side of the
suction pump P, in order to introduce the part of the diluted exhaust gas to the
bypass flow path, a suction pump has to be separately provided in the bypass flow
path L4 or on the lower stream side than the merging point Y. In contrast, in the
present embodiment, since the merging point Y is provided between the filter F
15 and the suction pump P, i.e., on the upstream side of the suction pump P as
described above, the part of the diluted exhaust gas can be introduced to the
bypass flow path L4 by the difference in pressure between the branching point X
and the merging point Y without separately providing a suction pump in the
bypass flow path L4 or the like.
20 [0076]
The bypass flow rate control mechanism 30 is one that controls the
bypass flow rate through the bypass flow path L4 in order to change the flow rate
of the diluted exhaust gas flowing through the filter F, and includes: a mass flow
controller 31 provided in the bypass flow path L4; and a control part main body
25 32 for controlling the mass flow controller 31.
28
[0077]
Note that although the mass flow controller 31 in the present embodiment
is of a differential pressure type, a mass flow controller of a thermal type may be
used.
[5 0078]
The control part main body 32 is one physically including a CPU, a
memory, an A/D converter, a D/A converter, and the like, and as illustrated in FIG.
7, configured to fulfill functions as a weighting factor storage part 33 and a bypass
flow rate setting part 34 in such a manner that the CPU and its peripheral devices
10 cooperate in accordance with a program stored in a predetermined area of the
memory.
[0079]
As illustrated in FIG. 7, the weighting factor storage part 33 is set in a
predetermined area of the memory, and stores test condition data indicating test
15 conditions preset in order to obtain test results. The test conditions here refer to
test conditions stipulated in regulations, exhaust gas measurement regulations, or
the like, test conditions arbitrarily set by an operator, or such other test conditions,
and the weighting factor storage part 33 in the present embodiment stores multiple
pieces of test condition data.
20 [0080]
The weighting factor storage part 33 in the present embodiment stores
multiple driving modes each indicating a vehicle running state, and flow rate
conditions on the flow rates of the diluted exhaust gas to be flowed through the
filter F in the respective driving modes in association with each other.
25 [0081]
29
Each of the flow rate conditions refers to a weighting factor set for PM
mass measured in each of the phases in order to obtain one test result, and here to
a weighting factor stipulated in, for example, regulations (such as CFR 1066)
[0082]
That is, the weighting factor storage part 33 stores a driving mode an5 d
weighting factors predetermined corresponding to respective phase intervals in the
driving mode in association with each other.
[0083]
More specifically, as illustrated in FIG. 8, the driving mode is constituted
10 by three phase intervals, and vehicle speeds and the like in the respective phase
intervals and weighting factors corresponding to the phase intervals are stored in
association with each other as one piece of test condition data. For example,
weighting factors in Phases 1 and 2 constituting a cold start region are set to 43 %
and 100 %, respectively, and a weighting factor in Phase 3 constituting a hot start
15 region is set to 57 %. In the second embodiment, as stipulated in predetermined
regulations, the weighting factors when omitting the test in Phase 4 are set for the
respective phase intervals
[0084]
As illustrated in 7, the bypass flow rate setting part 34 is one that from
20 the weighting factor storage part 33, acquires test condition data indicating test
conditions selected, for example, using input means by an operator, as well as on
the basis of the test condition data, controls the bypass flow rate.
[0085]
In more detail, the bypass flow rate setting part 34 transmits a control
25 signal to an unillustrated flow rate control valve of the mass flow controller 31
30
provided in the bypass flow path L4 so that the flow rate of the diluted exhaust
gas passing through the filter F in each phase interval becomes equal to a flow
rate resulting from multiplying a predetermined reference flow rate by a
weighting factor corresponding to the phase interval.
[5 0086]
More specifically, the bypass flow rate setting part 34 transmits the
control signal so that the ratio among the flow rates of the diluted exhaust gas
flowing through the filter F, i.e., the ratio among a first flow rate in Phase 1, a
second flow rate in Phase 2, and a third flow rate in Phase 3 becomes equal to the
10 ratio among the above-described weighting factors, i.e., 0.43:1: 0.57.
[0087]
The exhaust gas analysis apparatus 100 of the present embodiment
configured as described above operates in accordance with, for example, Steps
ST1 to ST7 as in a flowchart illustrated in FIG. 9. As can be seen when
15 comparing FIG. 5 illustrating the operation of the first embodiment and FIG. 9, the
operations in Steps S2 to S4 describing the change in split flow ratio in FIG. 5
correspond to the operations in Steps ST2 to ST5 describing the change in bypass
flow rate in the second embodiment.
[0088]
20 Specifically, first, regarding what kind of test is performed, an operator
sets the test condition in the control part main body 32 (Step ST1).
[0089]
Then, the bypass flow rate setting part 34 acquires the test condition data
and bypass ratio data from the weighting factor storage part 33 (StepST2).
25 [0090]
31
That is, a target bypass flow rate is set in the mass flow controller 31 so
that the diluted exhaust gas flows through the filter F at a ratio of 0.43 that is a
value corresponding to the weighting factor set for Phase 1. In this example, the
flow rate of the diluted exhaust gas flowing through the filter F only has to be
0.43 of the total flow rate of the diluted exhaust gas, and therefore, as the targe5 t
bypass flow rate, the bypass flow rate setting part 34 sets, in the mass flow
controller 31, a value resulting from multiplying the total flow rate of the diluted
exhaust gas achieved by the pump P by 0.57 (Step ST3).
[0091]
10 In Phase 2, the target bypass ratio only has to be 1 as compared with that
in Phase 1, and therefore it is only necessary that the total amount of the diluted
exhaust gas flows through the filter F. Accordingly, as the target bypass flow
rate, the bypass flow rate setting part 34 sets zero in the mass flow controller 31,
and a fully closed state is kept, i.e., a state where no diluted exhaust gas flows
15 through the bypass flow rate L4 is kept (Step ST4).
[0092]
Further, in Phase 3, the target bypass flow rate is set in the mass flow
controller 31 so that the diluted exhaust gas flows through the filter F at a target
bypass ratio of 0.57 corresponding to the weighting factor set for Phase 3. In
20 this example, the flow rate of the diluted exhaust gas flowing through the filter F
only has to be 0.57 of the total flow rate, and therefore as the target bypass flow
rate, the bypass flow rate setting part 34 sets, in the mass flow controller 31, a
value resulting from multiplying the total flow rate of the diluted exhaust gas
achieved by the pump P by 0.43 (Step ST5).
25 [0093]
32
Still further, the test proceeds, and before performing the test in the hot
start region, the bypass flow rate setting part 23 change the target bypass ratio to
0.57 that is a value corresponding to the hot start region. The first controller 26
continues to control the flow rate control valve V so as to obtain a target flow rate
of the diluent gas corresponding to the changed target bypass ratio (Step 5 tep S4).
[0094]
Note that in Steps S3 and S4, the second controller 27 continues the
control so that the flow rate of the diluted exhaust gas is kept constant by the
pump P. Also, the diluted exhaust gas passes through the filter F common to
10 both Steps S3 and S4.
[0095]
When the test in Phases 1 to 3 is finished, the filter F is detached, and the
amount of collected PM and the like are measured by a separate measurement
instrument (Step ST6).
15 [0096]
On the basis of a result obtained in Step ST6, the amount of PM
contained in the exhaust gas discharged from the internal combustion engine is
calculated (Step ST7).
[0097]
20 Next, a calibration method for the mass flow controller 31 in the second
embodiment configured as described above will be described with reference to
FIG. 10.
[0098]
First, a part where the filter F is provided in the diluted exhaust gas flow
25 path L3 is closed, and setting is performed so that fluid flows only through the
33
bypass flow path L4 (Step C1).
[0099]
Then, the opening level of a valve (not illustrated) of the mass flow
controller 31 is fixed to a predetermined opening level, and gas is flowed through
the bypass flow path L4 and the diluted exhaust gas flow path L3 after 5 r the
merging point (Step C2).
[0100]
Subsequently, the measured flow rate of the diluted exhaust gas measured
by the second flowmeter FM2 is acquired (Step C3), and with a value indicated by
10 the second flowmeter FM2 as a reference, the value of a flowmeter of the mass
flow controller 31 is set to the same value of the second flowmeter FM2 (Step
C4).
[0101]
When the flowmeter (not illustrated) of the mass flow controller 31 is not
15 calibrated at all calibration points (Step C5), an opening level of the valve of the
mass flow controller 31 is changed (Step C6), and Steps C3 to C5 are repeated
until calibration at all the calibration points is completed.
[0102]
Calibrating in this manner makes it possible to substantially match the
20 characteristics of the flowmeter of the mass flow controller 31 with the
characteristics of the second flowmeter FM2. Accordingly, even if a measured
value indicated by the second flowmeter FM2 deviates from an actual flow rate,
relative relationship to the value of a flow rate measured by the mass flow
controller 31 can be kept.
25 [0103]
34
Accordingly, the accuracy of the ratio of the flow rate of the diluted
exhaust gas bypassed through the bypass flow path L4 to the total flow rate of the
diluted exhaust gas can be always ensured. For this reason, a split flow ratio
corresponding to weighting to be achieved in each driving mode can be accurately
obtained, and the measurement accuracy of, for example, PM or the like, can 5 be
improved.
[0104]
An exhaust gas analysis apparatus 100 according to a third embodiment
of the present invention will be described with reference to FIG. 11. Note that
10 members corresponding to those described in the first embodiment are denoted by
the same reference signs.
[0105]
The exhaust gas analysis apparatus 100 of the third embodiment is
configured to sample exhaust gas from a main flow path ML constituting a
15 so-called full tunnel introduced with the total amount of the exhaust gas
discharged from an internal combustion engine, and change a dilution ratio to a
value corresponding to a weighting factor in each of phase intervals constituting a
driving mode. The exhaust gas analysis apparatus 100 further includes a bag
line L5 for containing the total amount of exhaust gas discharged in each phase
20 interval in an exhaust gas bag B in parallel in addition to a diluted exhaust gas
flow path L3 provided with a filter F for collecting particulate matter. The
measurement target component of the exhaust gas collected in the exhaust gas bag
B is analyzed in an analysis part A provided in the subsequent state. Not only
PM but also measurement target components such as CO, CO2, and NOx can be
25 measured using the exhaust gas collected in the exhaust gas bag B.
35
[0106]
In addition, on the upstream side of the main flow path ML, a dilution air
inflow port DA, and an introduction path IE for introducing the exhaust gas
discharged from a tail pipe or the like of a vehicle into the main flow path ML are
provided. Further, on the downstream side of the main flow path ML, a 5 main
pump PM is provided, and the exhaust gas is discharged from the main flow path
ML at a constant flow rate. Note that although in the first embodiment, the
original exhaust gas is the raw and undiluted exhaust, in the third embodiment, the
original exhaust gas is the exhaust gas that is raw exhaust gas diluted with the
10 dilution air flowing in from the inflow port DA
[0107]
First, a configuration for collecting particulate matter by the filter F is
described.
[0108]
15 In the third embodiment, a sampling flow path L1 is a part for splitting
the original exhaust gas flowing through the main flow path ML to sample part of
the original exhaust gas as sampling exhaust gas, and configured to be directly
merged with a diluent gas supply path L2. A flow path after merger of the
sampling flow path L1 and the diluent gas supply path L2 corresponds to the
20 diluted exhaust gas flow path L3, and is provided with the filter F and a pump P.
[0109]
As described in the first and second embodiments, the flow rate of the
diluent gas supplied from the diluent gas supply path L2 is configured to be
changed so as to obtain a dilution ratio corresponding to a weighting factor set for
25 each region or each phase interval in predetermined regulations.
36
[0110]
In the present embodiment, the total flow rate of the diluted exhaust gas
flowing through the diluted exhaust gas flow path L3 is controlled to be constant
by the pump P provided in the diluted exhaust gas flow path L3. For this reason,
by changing the flow rate of the diluent gas supplied from the diluent gas suppl5 y
path L3, the flow rate of the sampling exhaust gas splitting and sampled from the
original exhaust gas in the main flow path ML and can be indirectly changed.
That is, in the third embodiment, depending on a phase interval, a split flow ratio
control mechanism 20 changes a split flow ratio that is the ratio between the total
10 flow rate of the original exhaust gas and the split flow rate of the sampling
exhaust gas. Note that the split flow ratio in the third embodiment is represented
by [the total flow rate of the original exhaust gas (diluted raw exhaust gas) / the
split flow rate of the sample exhaust gas flowing through the sampling flow path
L1].
15 [0111]
For example, when the ratio among weighting factors in Phases 1, 2, and
3 is set to 0.43:1:0.57, the flow rate of the diluent gas flowing through the diluent
gas supply path L2 is controlled so that the ratio among split flow ratios in the
respective phase intervals becomes 2.32:1:1.75.
20 [0112]
In doing so, as with the first embodiment, measurement can be performed
corresponding to the weighting factors set for the respective phase intervals, and
particulate matter can be measured using the one filter F in accordance with
regulations.
25 [0113]
37
Next, a configuration for changing the flow rate of the exhaust gas to
sample it when the exhaust gas is split and sampled into the exhaust gas bag B
from the full tunnel ML through the bag flow path L5 in each phase interval is
described.
[5 0114]
The bag flow path L5 is provided with a mass flow controller MFC, a
bag flow path pump P5, and the exhaust gas bag B from the upstream side. Note
that the exhaust gas bag B corresponds to a collection part in claims.
[0115]
10 The mass flow controller MFC is one that controls the flow rate of the
sampling exhaust gas splitting and sampled from the original exhaust gas flowing
through the main flow path ML in each phase interval so that the flow rate
becomes equal to a flow rate corresponding to a weighting factor in the phase
interval.
15 [0116]
In the third embodiment, when the ratio among the weighting factors in
Phases 1, 2 and 3 is 0.47:1:0.53, the ratio among target flow rates to be set in the
mass flow controller MFC in the respective phases is also set to be 0.47:1:0.53.
The exhaust gas sampled into the bag flow path L5 in each phase interval is
20 directly contained without replacing the exhaust gas bag B.
[0117]
In doing so, the exhaust gas can be sampled from the full tunnel ML at a
flow rate reflecting a weighting factor in each phase interval, and sampling using
the one exhaust gas bag B makes it possible to measure the particulate matter or
25 other materials in accordance with predetermined regulations.
38
[0118]
In addition, the third embodiment is configured to be able to analyze the
measurement target component in the exhaust gas using both the filter F and the
exhaust gas bag B, but may be configured to analyze the measurement target
component in the exhaust gas using only any one of the filter F and the exha5 ust
gas bag B. In this case, the main flow path ML may be provided with only any
one of the sampling flow path L1 and the bag flow path L5.
[0119]
Note that the present invention is not limited to any of the
10 above-described embodiments.
[0120]
For example, in the above-described embodiments, the flow rate
conditions corresponding to respective regions or phases are weighting factors
stipulated in regulations, but may be flow rates or a flow rate ratio. Also, when
15 the ratio among weighting factors in Phases 1, 2, 3, and 4 is 0.754:0.754:1:1, split
flow ratios or split flow rates in the respective phase intervals only have to be set
to values reflecting these weighting factors.
[0121]
In addition, the filter is not necessarily required to be provided in the
20 diluted exhaust gas flow path. For example, a continuous PM meter or other
various exhaust gas analysis devices may be provided to measure PM in the
diluted exhaust gas.
[0122]
Further, the present invention may include mass flow controllers
25 respectively provided in the diluent gas supply path and the diluted exhaust gas
39
flow path.
[0123]
Also, the measurement accuracy of a mass flow controller is likely to be
affected by exhaust gas, and therefore, in order to accurately control the flow rates
of the diluent gas and diluted exhaust gas, the present invention preferably 5 include
venturi flowmeters as in the above-described embodiments.
[0124]
In addition, each of the above-described exhaust gas analysis apparatus is
one having the one dilution tunnel, but may be configured to multiple dilution
10 tunnels and dilute the exhaust gas discharged from the internal combustion engine
in a multistep manner.
[0125]
The calibration method described in the second embodiment may be
applied to the first embodiment. In this case, it is only necessary to calibrate the
15 first flowmeter with the second flowmeter as a reference. Even in such a case,
since the relative relationship between the respective flowmeters is kept, the
dilution ratio can be accurately kept, and PM or the like can be accurately
measured as in the second embodiment.
[0126]
20 In place of the filter used as the collection part in each of the
embodiments, a diffusion changer sensor (DCS) that fulfill functions as the
collection part and the analysis part may be installed to simultaneously collect and
analyze the measurement target component. Also, a particle number (PN)
measurement device may be provided so as to fulfill functions as the collection
25 part and the analysis part in place of the filter.
40
[0127]
Further, a bag mini-diluter (BMD) can also be applied to the present
invention, and measurement and analysis reflecting weighting based on
regulations can be performed in the same manner.
[5 0128]
The present invention is applicable not only to the test that actually runs a
vehicle, but also to a test using, for example, an engine dynamometer or the like,
only for an internal combustion engine. That is, in the case of a test for a part of
a vehicle as well, the present invention can produce the same effects as described
10 above.
[0129]
Besides, it should be appreciated that the present invention is not limited
to any of the above-described embodiments, and various variations and parts of
the respective embodiments can be combined without departing from the scope
15 thereof.
Reference Signs List
[0130]
100: Exhaust gas analysis apparatus
20 F: Filter
L3: Diluted exhaust gas flow path
20: Split flow ratio control mechanism

WE CLAIM:
1. An exhaust gas analysis apparatus comprising:
a collection part that collects a measurement target component in
sampling exhaust gas partially or wholly splitting from original exhaust gas; 5 ; and
a split flow ratio control mechanism configured to, during a test of a
vehicle or a part of the vehicle, change a split flow ratio that is a ratio of a split
flow rate of the sampling exhaust gas to a total flow rate of the original exhaust
gas.
10
2. The exhaust gas analysis apparatus according to claim 1, wherein
the split flow ratio control mechanism is configured to change the split
flow ratio in accordance with a vehicle driving mode set in compliance with a
predetermined regulation.
15
3. The exhaust gas analysis apparatus according to claim 1, wherein
in multiple phase intervals constituting a driving mode, the sampling
exhaust gas flows to the collection part in common.
20 4. The exhaust gas analysis apparatus according to claim 2, wherein
the driving mode is constituted by multiple phase intervals,
weighting factors are set for the respective phase intervals, and
the split flow ratio control mechanism is configured to change the split
flow ratio in dependence on the weighting factors set for the respective phase
25 intervals.
42
5. The exhaust gas analysis apparatus according to claim 2, wherein
the driving mode is constituted by:
a cold start region that is constituted by one or more phase intervals and
in which the vehicle is cold started; 5 d; and
a hot start region that is constituted by one or more phase intervals and in
which the vehicle is hot started,
weighting factors are respectively set for the cold start region and the hot
start region, and
10 the split flow ratio control mechanism is configured to change the split
flow ratio in dependence of the weighting factors set for the cold start region and
the hot start region.
6. The exhaust gas analysis apparatus according to claim 5, wherein
15 the cold start region is constituted by a first phase interval and a second
phase interval,
the hot start region is constituted by a third phase interval,
a ratio among weighting factors respectively for the first phase interval,
the second phase interval, and the third phase interval is set to a:1:(1 – a), and
20 the split flow ratio control mechanism is configured to change the split
flow ratio among the respective phase intervals so that a ratio among split flow
ratios in the first phase interval, the second phase interval, and the third phase
interval becomes 1/a:1:1/(1 – a).
25 7. The exhaust gas analysis apparatus according to claim 1, further
43
comprising:
a main flow path through which the original exhaust gas flows;
a sampling flow path through which the sampling exhaust gas splitting
from the original exhaust gas flows;
a diluent gas supply path through which diluent gas 5 s flows; and
a diluted exhaust gas flow path that is a flow path after merger of the
sampling flow path and the diluent gas supply path.
8. The exhaust gas analysis apparatus according to claim 7, wherein
10 the split flow ratio control mechanism comprises:
a main flowmeter that measures the total flow rate of the original exhaust
gas flowing through the main flow path;
a first flowmeter that measures a flow rate of the diluent gas flowing
through the diluent gas supply path;
15 a flow rate control valve that is provided in the diluent gas supply path;
a second flowmeter that measures a flow rate of diluted exhaust gas
flowing through the diluted exhaust gas flow path;
a split flow ratio setting part that sets a target split flow ratio in
accordance with a driving mode,
20 a target flow rate calculation part that, on a basis of the target split flow
ratio set by the split flow ratio setting part, the total flow rate of the original
exhaust gas, the total flow rate being measured by the main flowmeter, and a
measured flow rate of the diluted exhaust gas, the measured flow rate being
measured by the second flowmeter, calculates a target flow rate of the diluent gas
25 flowing through the diluent gas supply path, and
44
a first controller that controls the flow rate control valve so that a
deviation between a measured flow rate of the diluent gas, the measured flow rate
being measured by the first flowmeter, and the target flow rate calculated by the
target flow rate calculation part decreases.
5
9. The exhaust gas analysis apparatus according to claim 8, wherein
the split flow ratio control mechanism further comprises:
a pump provided in the diluted exhaust gas flow path; and
a second controller that controls the pump so that the flow rate of the
10 diluted exhaust gas flowing through the diluted exhaust gas flow path becomes
constant at a predetermined flow rate.
10. An exhaust gas analysis system further comprising:
the exhaust gas analysis apparatus according to claim 1; and
15 an analysis part that analyzes the measurement target component
collected by the collection part.
11. An exhaust gas analysis method using an exhaust gas analysis
apparatus comprising a collection part that collects a measurement target
20 component in sampling exhaust gas partially or wholly splitting from original
exhaust gas, the exhaust gas analysis method comprising
a split flow ratio changing step of, during a test of a vehicle or a part of
the vehicle, changing a split flow ratio that is a ratio of a split flow rate of the
sampling exhaust gas to a total flow rate of the original exhaust gas.
25
45
12. A program recording medium recorded with a program for an exhaust
gas analysis apparatus,
the program used for the exhaust gas analysis apparatus comprising a
collection part that collects a measurement target component in sampling exhaust
gas partially or wholly splitting from original exhaust ga5 s,
the program instructing a computer to fulfill a function as a split flow
ratio control part that, during a test of a vehicle or a part of the vehicle, changes a
split flow ratio that is a ratio of a split flow rate of the sampling exhaust gas to a
total flow rate of the original exhaust gas.
10
13. A calibration method for an exhaust gas analysis apparatus
comprising: a diluted exhaust gas flow path through which diluted exhaust gas
resulting from, with diluent gas, diluting sampling exhaust gas partially or wholly
splitting from original exhaust gas flows; a collection part that is provided in the
15 diluted exhaust gas flow path and collects particulate matter in the diluted exhaust
gas; a bypass flow path that, in the diluted exhaust gas flow path, branches from
an upstream side of the collection part and merges with a downstream side of a
filter; a second flowmeter that is provided on a lower stream side than a merging
point of the bypass flow path in the diluted exhaust gas flow path and measures a
20 flow rate through the diluted exhaust gas flow path; and a bypass flow rate control
mechanism that controls a bypass flow rate of the diluted exhaust gas flowing
through the bypass flow path, wherein the bypass flow rate control mechanism
comprises a bypass flowmeter that measures the bypass flow rate of the diluted
exhaust gas flowing through the bypass flow path,
25 the calibration method comprising:
46
closing an inflow path to the filter; and
calibrating the bypass flowmeter with the second flowmeter as a
reference flowmeter.