JP2009030512A - Core member attached to flow passage cross-sectional area increasing device and flow path cross-sectional area increasing device provided with core member - Google Patents

Abstract

[PROBLEMS] To reduce pressure loss in a diffuser even when the length of the diffuser is short, and at the same time uniformize the flow at the outlet of the diffuser, so that the pressure loss can be achieved without having to lengthen the entire device. The present invention provides a flow passage cross-sectional area increasing device in which a fluid to be treated having a small flow and a good flow distribution in a large area downstream flow pipe is fed.
A flow passage of a flow body in which an upstream flow pipe having a small cross-sectional area, a downstream flow pipe having a large cross-sectional area, and a diffuser 4 are connected therebetween. In the cross-sectional area increasing device, the core member 10 is provided on the central axis of the upstream portion inside the diffuser, and the rate of increase in the cross-sectional area of the flow passage in the diffuser formed between the core member and the diffuser wall is constant. The core member shape was formed so as to be.
[Selection] Figure 3

Description

  The present invention relates to a cross-sectional area of a flow passage of a flow body formed by connecting an upstream flow pipe having a small cross-sectional area to which a fluid to be treated is flowed, a large-area downstream flow pipe, and a diffuser therebetween. In particular, a core member attached to an inflow passage cross-sectional area increasing device suitable for inflow gas in an exhaust gas treatment device, a heat exchanger, etc. from an internal combustion engine such as an automobile or a gas turbine, and the core member The present invention relates to a flow passage cross-sectional area increasing device provided.

In recent years, automobile exhaust gases have a serious impact on the air environment on a global scale.
One example is photochemical smog. This photochemical smog synthesizes harmful tearing substances by reacting NOx in the atmosphere with hydrocarbons HC under sunlight.
The main source of nitrogen oxides NOx and hydrocarbon HC is the exhaust gas of automobiles, and about 70% of hydrocarbon exhaust gas and 60% of nitrogen oxides are emitted, which is the largest source of photochemical smog. It has become.

Therefore, all automobile companies around the world are working to protect the environment as one of the most important issues.
As a device for treating such exhaust gas, a so-called catalytic converter that converts harmful gas in the exhaust gas into harmless water H2O and carbon dioxide CO2 has been developed, and this is installed in the exhaust gas path to treat harmful components. ing.
Incidentally, before the catalytic converter was developed, in the United States, 14 tons / Km2 of pollutants were discharged annually from all vehicles. However, the development of catalytic converters has reduced them to 0.3 tons / Km2 annually. The catalytic converter has a great effect on the above.

In order to improve the processing efficiency of the catalytic converter, it is preferable to make the volume of the processing portion as large as possible. For this reason, as a general catalytic converter structure, a structure provided with a diffuser immediately before a monolithic carrier is used (Non-patent Document 1).
A diffuser is a spreading tube whose cross-sectional area gradually increases. The role of the diffuser is to guide the fluid to the required location with as little pressure loss as possible, and to guide the flow downstream with the flow distributed as uniformly as possible in the cross section of the flow path.

If the spread angle of the diffuser is small, it is necessary to lengthen the diffuser in order to expand it to a desired size. From the viewpoint of space, the spread angle of the diffuser is usually about 70 °. When such a diffuser is used, the flow near the tube wall of the diffuser gradually loses velocity energy due to friction with the tube wall, and finally stops. Thereafter, the flow is separated from the wall by the reverse flow due to the reverse gradient of the pressure.
Thus, the occurrence of energy loss due to pressure loss and the deterioration of the uniformity of the flow in the pipe lead to problems such as a decrease in the maximum output of the engine, a deterioration in fuel consumption, and a decrease in exhaust gas processing performance.

Non-Patent Document 1 proposes a diffuser shape that reduces the pressure loss in consideration of the length of the diffuser.
This diffuser is such that the spread angle is reduced to 3.5 ° to 11 ° on the inlet side of the diffuser, and the diffuser rapidly expands immediately before being connected to the catalytic converter. When the diffuser having such a shape is used, the pressure loss can be reduced, but the difference in flow velocity between the vicinity of the center and the vicinity when entering the catalytic converter is large.
In order to improve the catalytic action, it is important to raise the temperature in the monolith support above a certain temperature (about 700 ° C.). Since the temperature of the portion where the exhaust gas flow rate is fast is likely to rise, and the portion where the flow rate is slow is low, there is a problem that the purification action by the catalyst is reduced if the flow just before the monolith carrier is unevenly distributed.

Therefore, in order to cope with these problems, the inventor of the present invention prior to the present invention, a small cross-sectional area upstream flow pipe to which a fluid to be treated is flowed, and a large cross-sectional area downstream flow pipe, In addition, in a flow passage cross-sectional area increasing device for a flow body formed by connecting a diffuser therebetween, a core member is provided on the central axis of the upstream portion inside the diffuser, and formed between the core member and the diffuser wall. A flow passage cross-sectional area increasing device is proposed in which the core member shape is formed so that the increasing rate of the flow path cross-sectional area is constant (Patent Document 1).
However, in the flow passage cross-sectional area increasing device according to the previous proposal, the core member has a shape in which a predetermined orifice is formed at the tip portion of the conical shape and a fluid passage extending downstream from the orifice portion is formed. Therefore, there has been a problem that productivity is lowered.
JP 2006-183665 A US Magazine Automotive Engineering / June 1996 Page 69 Reducing catalytic converter pressure loss

  The present invention has been proposed in view of the above-described problems. Even if the length of the diffuser is not long, the pressure loss is small, and the fluid to be treated has a good flow distribution in the large-area downstream flow pipe. In order to make it possible to promptly start processing of the fluid to be processed, the core member attached to the apparatus for increasing the cross-sectional area of the flow path is highly productive and the flow path is highly practical. An object of the present invention is to provide an area increasing device.

  In order to achieve the above object, the core member attached to the flow passage cross-sectional area increasing apparatus according to the present invention includes a small cross-sectional area upstream of a small cross-sectional area in which a fluid to be treated is flowed, and a large cross-sectional area downstream. A core member attached to a side flow pipe and a flow passage cross-sectional area increasing device of a flow body formed by connecting a diffuser between the side flow pipe, and an orifice is provided on the central axis of the upstream portion inside the diffuser. A shape that is drilled and has a length of 1/2 to 4/5 of the length of the diffuser portion, and the rate of increase in the cross-sectional area of the flow path formed between the core member and the diffuser wall is substantially constant In addition, the main feature is that it is formed by a molding means.

  The core member attached to the flow passage cross-sectional area increasing device according to the present invention is characterized in that the molding means is a deep drawing molding device or a rotary molding device.

  Further, in the flow passage cross-sectional area increasing device according to the present invention, an orifice is formed in an upstream portion inside the diffuser, and has a length of ½ to 4/5 of the length of the diffuser portion, and The core member formed by the molding means is arranged on the central axis of the diffuser inside the diffuser so that the increasing rate of the flow path cross-sectional area formed between the core member and the diffuser wall is almost constant. Is the most important feature.

  According to the present invention, the core member is provided on the center axis of the diffuser on the inner side of the inclined portion of the diffuser and from the boundary with the upstream flow pipe toward the downstream flow pipe side, The shape of this core member that makes the rate of increase in the cross-sectional area of the flow path constant is formed by forming means made of a metal plate with a deep drawing molding device or a rotary molding device. Even if it does not take a long time, the processed fluid supplied from the upstream flow pipe is supplied almost uniformly to the processed portion, and the flow of the processed fluid in the diff user is made uniform and at the same time the pressure loss is reduced. While maintaining the effect that the pressure loss of the entire flow path can be reduced, there is an advantage that the core member can be easily produced in large quantities and at low cost by the molding means.

  In addition, since the core member is simple and can be produced in large quantities at low cost, there is also an advantage that a highly practical flow passage cross-sectional area increasing device can be provided at low cost.

A preferred embodiment of a core member attached to a flow passage cross-sectional area increasing device according to the present invention and a flow path cross-sectional area increasing device provided with the core member will be described below with reference to the drawings.
FIG. 1 is a schematic diagram of an experimental apparatus simulating an exhaust gas treatment apparatus such as an automobile. In FIG.
This experimental apparatus 1 is a flow feeder that connects a blower 2 corresponding to an automobile engine, a monolithic carrier type catalytic converter (downstream flow pipe) 3, and a diffuser 4 attached to the inlet portion of the catalytic converter 3. A pipe (upstream flow pipe) 5 and an outlet pipe 6 attached to the outlet side portion of the catalytic converter 3 are provided.
Further, a core member 10 described later is provided in the diffuser 4.

Here, the catalytic converter 3, the diffuser 4, and the flow pipe (upstream flow pipe) 5 connected in communication have a circular cross-sectional shape.
The inlet run-up section 7 of the flow pipe 5 is set to 1000 mm, and the flow pipe 5 and the outlet pipe 6 have an inner diameter D = 26 mm.

In this example, the divergence angle of the diff user 4 is set to 70 degrees.
As the monolithic support type catalytic converter 3, one having a wall thickness of 4 mm and a cell density of 400 cpsi was used.
As a measuring instrument such as a flow rate, as shown in FIG. 1, a stainless steel Pitot tube 8, 8a, a precision fine differential pressure gauge 9, and a liquid column type pressure gauge were used.
The precision fine differential pressure gauge 9 and the liquid column type pressure gauge were as follows.
The Pitot tube 8 is installed in a portion where the flow is sufficiently developed.
1) Precision fine differential pressure gauge Shibata Kagakuki Kogyo Co., Ltd. ISP-3-50SS type Measurement range 0-50 (mmH2O)
2) Liquid column type pressure gauge, manufactured by Okano Manufacturing Co., Ltd. Measurement range 0-300mmH2O

Further, in order to measure the pressure loss in the catalytic converter 3, as shown in FIG. 1, static pressure holes 11 and 12 are opened in the flow pipe 5 and the outlet pipe 6, respectively. Detection tubes 13 and 14 are attached.
The static pressure hole 12 opened in the outlet pipe 6 is provided in a place where it is considered that the contracted flow by the contracting portion 15 does not affect.

Next, a method for calculating the flow rate in the experimental apparatus 1 simulating the exhaust gas processing apparatus configured as described above and a method for measuring the pressure loss in the catalytic converter 3 will be described.
First, the flow rate is calculated by measuring the difference between the total pressure and the static pressure at the center of the circular tube with a Pitot tube 8 provided in the flow pipe 5 as shown in FIG. Then, the total flow rate is calculated using a 1/7 power law described later.
Next, as shown in FIG. 1, the method for measuring the pressure loss in the catalytic converter 3 is the static pressure between the flow pipe 5 and the outlet pipe 6 after passing through the catalytic converter 3 as the pressure loss of the entire catalytic converter 3. Measure the difference with a fine differential pressure gauge.
And the flow velocity measuring method of the exit pipe | tube 6 part after passing the catalytic converter 3 installs so that the front-end | tip of the Pitot pipe 8a may come to the static pressure hole 12 of the position of about 70 mm from immediately after the catalytic converter 3. FIG.

Thereafter, the Pitot tube 8 is moved in order from the side wall of the flow tube 5 to the center of the flow tube 5 at intervals of 1 mm, and the difference between the total pressure and the static pressure in the outlet tube 6 is measured by the micro differential pressure gauge 9, and the differential pressure is measured. The flow rate is calculated from
Here, the reason why the flow velocity measurement was not performed immediately after the catalytic converter 3 is that the flow coming out of the catalytic converter 3 is very disturbed.
At a position of about 70 mm immediately after the catalytic converter 3, the flow disturbance is small and the reproducibility is taken, so that measurement is performed at this position.

In this example, the divergence angle of the diff user 4 is set to a general 70 °, and an object is placed therein, thereby reducing the pressure loss in the diff user 4 and making the flow uniform at the same time. And
First, the pressure loss was evaluated by measuring the pressure difference before and after the catalytic converter 3 and making it dimensionless.
The experimental apparatus and the method for measuring the pressure loss in the catalytic converter 3 are the same as those previously proposed by the inventors.

The core member 10 has the same center axis as the diffuser 4.
The core member 10 is formed by forming a plate-like member into a conical shape having a linear inclined surface by deep-drawing a plate-like member by pressing (molding means), and having an orifice 16 at the top (tip). The diameter d of 16 is set to a diameter at which the ratio of the pressure loss to the downstream maximum diameter D is 0.576 where the pressure loss is the most reduced value as a result of the experiment.
In this example, the length L of the core member 10 is 20 mm in accordance with the shape of the catalytic converter 3, and the inclination angle of the peripheral surface is substantially the same as the area increase rate shown in FIG. The angle is such that the increase rate is constant.

Since the change in the length L of the core member 10 in the diffuser 4 also affects the pressure loss, the length of the core member 10 is 30 mm, which is 3/4 of the length of the diffuser 4 being 40 mm. In order to make it preferable, the length of the core member 10 is 30 mm.
Incidentally, when the length of the diffuser portion is less than 1/2 or exceeds 4/5, the pressure loss becomes high. Therefore, the length of the diffuser portion is preferably in the range of 1/2 to 3/4.

In the above embodiment, the core member 10 is formed into a conical shape having a straight inclined surface with an inclination angle of 10 degrees by deep drawing a plate-like member by pressing (molding means). However, the present invention is not limited to this, and it is also possible to perform molding by so-called rotational molding, in which a molded body such as a plate-shaped member or a cylindrical member is rotated to perform partial continuous molding.
In addition, when the core member 10 is formed by pressing (molding means) using a mold, it is possible to easily produce a hemispherical portion near the Oris 16 as shown in FIG. 4 by changing the pressing mold. can do.
In the case of deep drawing by pressing (molding means), the core member 10 having different thicknesses as shown in FIG. 5 can be formed by changing the stretching rate.
As shown by the symbol A of the area increase rate in FIG. 6, the area increase rate of the core member 10 shown in FIG. It was confirmed that there was no inferiority in the effects such as pressure loss of the core member 10 in the above embodiment.

The core member and the flow passage cross-sectional area increasing device provided with the core member in the above embodiment are devices for processing exhaust gas for automobiles, but can also be used for exhaust gas processing of internal combustion engines such as ships. it can.

It is the schematic of the experimental apparatus which simulated the exhaust gas processing apparatus. It is a vertical side view of a core member. It is a vertical side view of the diff user part which provided the core member. It is a longitudinal cross-sectional view of the modification of a core member. It is a longitudinal cross-sectional view which shows another modification of a core member. It is a vertical side view of the diff user part with which the core member of the modification was mounted | worn.

Explanation of symbols

4 ... Diffuser part 10 ... Core member 16 ... Orifice

Claims (3)

  An apparatus for increasing the cross-sectional area of the flow passage of the flow body formed by connecting the upstream flow pipe with a small cross-sectional area, the downstream flow pipe with a large cross-sectional area, and a diffuser between them. An attached core member, wherein an orifice is formed on the central axis of the upstream portion inside the diffuser, has a length of ½ to 4/5 of the length of the diffuser portion, and the core member A core member attached to the flow passage cross-sectional area increasing device, characterized in that it is formed by molding means into a shape in which the rate of increase in the cross-sectional area of the flow path formed between the gas and the diffuser wall is substantially constant.   The core member attached to the flow passage cross-sectional area increasing device according to claim 1, wherein the molding means is a deep drawing molding device or a rotary molding device for a metal plate material.   An orifice is drilled in the upstream portion inside the diffuser, has a length that is 1/2 to 4/5 the length of the diffuser portion, and is formed between the core member and the diffuser wall. A flow passage cross-sectional area increasing device, wherein a core member formed by molding means is disposed on a central axis of a diffuser inside a diffuser so as to have a substantially constant area increase rate.

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