EXHAUST GAS DILUTION DEVICE AND EXHAUST GAS MEASURING SYSTEM USING THE SAME

Abstract

In order to provide an exhaust gas dilution device capable of making a flow rate range wider than before, the exhaust gas dilution device is adapted to include a dilution tunnel through which diluent gas such as air flows, an orifice member adapted to block the dilution tunnel except for an orifice hole provided in a central part, and an exhaust gas introduction pipe 1 of which a discharge port is disposed so as to face to the orifice hole and face to a downstream side and through which exhaust gas is discharged from the discharge port into the dilution tunnel. In addition, in the exhaust gas dilution device, the orifice member is formed with a concave part that is gradually concaved from an outer circumferential edge part toward the orifice hole as viewed from an upstream side.

Claims

1. An exhaust gas dilution device comprising: a dilution pipe through which diluent gas such as air flows; an orifice member adapted to block the dilution pipe except for an orifice hole provided in a central part; and an exhaust gas introduction pipe of which a discharge port is disposed so as to face to or penetrate through the orifice hole and face to a downstream side and through which exhaust gas is discharged from the discharge port into the dilution pipe, wherein the orifice member is formed with a concave part that is gradually concaved from an outer circumferential edge part toward the orifice hole as viewed from an upstream side.

2. The exhaust gas dilution device according to claim 1, wherein the orifice member is one forming a hollow truncated conical shape.

3. The exhaust gas dilution device according to claim 1, wherein a tilt angle of a surface of the concave part is set to be 45 to 60 with respect to an inner circumferential surface of the dilution pipe in a virtual cross section obtained by cutting the dilution pipe along an axial line of the dilution pipe.

4. An exhaust gas measuring system comprising: the exhaust gas dilution device according to claim 1; and an exhaust gas measuring device adapted to sample mixed gas of the exhaust gas and the diluent gas, the mixed gas being produced by the exhaust gas dilution device, and measure a concentration or an amount of a predetermined component contained in the exhaust gas.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is an overall schematic diagram of an exhaust gas dilution device and an exhaust gas measuring system in one embodiment of the present invention;

[0024] FIG. 2 is a vertical cross-sectional view in which an orifice member in the same embodiment is cut along an axial line;

[0025] FIG. 3 is a perspective cross-sectional view illustrating a state where the orifice member in the same embodiment is cut along the axial line;

[0026] FIG. 4 is a vertical cross sectional view in which an orifice member in another embodiment of the present invention is cut along an axial line;

[0027] FIG. 5 is a vertical cross sectional view in which an orifice member in still another embodiment of the present invention is cut along an axial line;

[0028] FIG. 6 is an overall schematic diagram of an exhaust gas dilution device and an exhaust gas measuring system in yet another embodiment of the present invention; and

[0029] FIG. 7 is a vertical cross-sectional view in which an orifice member in yet another embodiment of the present invention is cut along an axial line.

DESCRIPTION OF EMBODIMENTS

[0030] In the following, one embodiment of the present invention will be described with reference to drawings.

[0031] As illustrated in FIG. 1, an exhaust gas dilution device 100 according to the present embodiment is one of a full flow dilution type, and used as part of an exhaust gas measuring system X.

[0032] Specifically, the exhaust gas dilution device 100 includes: an exhaust gas sampling pipe 1 that is connected to an exhaust pipe (not illustrated) of an internal combustion engine and into which the total amount of exhaust gas is introduced; a circular pipe-shaped dilution tunnel 2 (hereinafter also simply referred to as a tunnel 2) as a dilution pipe into which the exhaust gas is introduced through the exhaust gas sampling pipe 1 and also air as diluent gas is introduced to mix them for diluting the exhaust gas; and a flow rate control device (CVS) 9 that makes the flow rate of mixed gas flowing through the tunnel 2 constant.

[0033] Note that numeral 4 in the diagram represents an exhaust gas measuring device constituting part of the exhaust gas measuring system X. Here, as an example of the exhaust gas measuring device, a filter collection device adapted to proportionally sample the mixed gas flowing through the tunnel 2, and samples PM contained in the sampled mixed gas is illustrated. As another exhaust gas measuring device, one adapted to measure the concentrations and amounts of various components such as CO.sub.2, THC, and NO.sub.x in the exhaust gas can be cited.

[0034] In addition, in the present embodiment, the tunnel 2 is provided with a gas mixing structure 5 adapted to facilitates the mixture of the air and the exhaust gas.

[0035] The gas mixing structure 5 is one that includes an orifice member 51 having an orifice hole 5a in the center.

[0036] As illustrated in FIG. 2, the orifice member 51 is one forming a hollow truncated conical shape of which the outer circumferential edge is joined to the inner circumferential surface of the tunnel 2 without any gap in the middle of the tunnel 2, and disposed such that as viewed from the upstream side, the central part thereof is concaved to form a concave part S. The tilt angle of the surface of the concave part S is configured to be 45 to 60 with respect to the inner circumferential surface of the tunnel 2 as viewed in a virtual cross section obtained by virtually cutting along an axial line as illustrated in the diagram.

[0037] In addition, the terminal part of the exhaust gas sampling pipe 1 is extended from the upstream side toward the downstream side along the axial line of the tunnel 2, and a discharge port 1a of the exhaust gas sampling pipe 1 is configured to face to the downstream side on the upstream side of the orifice hole 5a. More specifically, the discharge port 1a is arranged coaxially with the orifice hole 5a so as to be positioned slightly upstream of (the surface on the upstream side of) the orifice hole 5a. Note that here the outside diameter of the exhaust gas sampling pipe 1 is set to be slightly smaller than the inside diameter of the orifice hole 5a.

[0038] In such a configuration, the air flows into the orifice hole 5a at a tilt from the gap between the terminal outer circumferential edge of the exhaust gas sampling pipe 1 and the surface of the concave part S, and mixes with the exhaust gas that is discharged from the exhaust port 1a and flows into the orifice hole 5a.

[0039] In this case, since a flow path of the air is gradually narrowed by the tilt surface of the concave part S of the orifice member 51 and then reaches the orifice hole 5a, even when increasing an air flow rate, a pressure loss is small, and therefore the mixing effect hardly changes according to the knowledge of the inventor.

[0040] As a result, since the exhaust gas dilution device 100 is capable of making a flow rate range larger than before, various patterns of tests can be done, and also a test of internal combustion engines having variously-sized displacements is also acceptable.

[0041] Note that the surface of the concave part S of the orifice member 51 does not have a constant angle, but as illustrated in FIG. 4, may be one having an angle that gradually decreases or increases toward the downstream side like a horn.

[0042] The orifice member 51 is not limited to a thin one, but as illustrated in FIG. 5, may be made thick to form the concave part S. In the case of FIG. 5, the surface on the downstream side of the orifice member 51 is perpendicular to the axis.

[0043] The terminal of the exhaust gas sampling pipe may be present on the upstream side of the orifice hole, be flush with the orifice hole, or penetrate through the orifice hole to be positioned on the downstream side of the orifice hole.

[0044] A dilution range may be determined with at least one or more of an aperture ratio of the orifice hole (the area of the orifice hole with respect to the inner circumferential cross-sectional area of the tunnel), the axial direction distance between the terminal of the exhaust gas sampling pipe and the orifice hole, the outside diameter of the exhaust gas sampling pipe and the inside diameter of the orifice hole, and the tilt angle of the concave part surface of the orifice member as parameters.

[0045] It goes without saying that as the dilution pipe, not only the so-called dilution tunnel but a general piping component may be used.

[0046] In addition, the present invention can also be applied to a partial dilution device.

[0047] FIG. 6 illustrates an example of the partial dilution device.

[0048] In the diagram, numeral 1 represents an exhaust gas sampling pipe adapted to sample part of raw exhaust gas discharged from an internal combustion engine E.

[0049] Numeral 2 represents a dilution tunnel (hereinafter also simply referred to as a tunnel) adapted to introduce the raw exhaust gas thereinto through the exhaust gas sampling pipe 1 as well as introducing air as diluent gas thereinto to dilute the exhaust gas with the air.

[0050] Numeral 3 represents a flow rate control device adapted to perform control to make the flow rate of the exhaust gas sampled through the exhaust gas sampling pipe 1 equal to a predetermined ratio of the total flow rate of the exhaust gas discharged from the internal combustion engine E. The flow rate control device 3 is configured to include: a constant flow rate keeping mechanism 31 adapted to keep the flow rate of mixed gas led out of the tunnel 2 constant; and a diluent gas flow rate control mechanism 32 adapted to control the flow rate of the air to be introduced into the tunnel 2 in accordance with the exhaust gas flow rate.

[0051] The constant flow rate keeping mechanism 31 is one including a pump 311 provided downstream of a filter collection device 4 and a mixed gas flow rate sensor 312, in which a control circuit 6 controls the rotation speed of the pump 311 so as to make the mixed gas flow rate measured by the mixed gas flow rate sensor 312 constant.

[0052] The diluent gas flow rate control mechanism 32 is one including: an adjustment mechanism 321 that is provided in an air introduction flow path connected to an introduction port 2b of the tunnel 2 and adapted to adjust the flow rate of the air to be introduced into the tunnel 2; an air flow rate measurement sensor 322 adapted to measure the air flow rate; and an exhaust gas flow rate sensor 323 adapted to measure the total flow rate of the exhaust gas discharged from the internal combustion engine E. Also, the control circuit 6 controls the air flow rate such that a sampling flow rate calculated by subtracting the air flow rate measured by the air flow rate measurement sensor 322 from the mixed gas flow rate becomes equal to the predetermined ratio of the exhaust gas total flow rate measured by the exhaust gas flow rate sensor 323.

[0053] Numeral 4 represents an exhaust gas analyzing device, and as the exhaust gas analyzing device, a filter collection device adapted to sample PM contained in the mixed gas of the exhaust gas and the air discharged from the tunnel 2 is illustrated here.

[0054] Besides, various modifications and combinations of the embodiments may be made without departing from the scope of the present invention.

REFERENCE SIGNS LIST

[0055] X: Exhaust gas measuring system [0056] 100: Exhaust gas dilution device [0057] 1: Exhaust gas introduction pipe [0058] 1a: Discharge port [0059] 2: Dilution tunnel [0060] 51: Orifice member [0061] 5a: Orifice hole [0062] S: Concave part