JP2007071081A - Ceramic honeycomb filter pressure loss measuring apparatus and pressure loss measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure loss measuring method and measuring apparatus for a ceramic honeycomb filter capable of ensuring sealing performance with a simple configuration and easily and reliably measuring a pressure loss of a sample.
A gas source for measuring pressure loss of a sample, a sample holder 3 in which a gas hole 12 through which the gas flows is formed, a gas pipe 10 connecting the gas source and the gas hole 12, and A flow rate measuring device 2 for detecting a gas flow rate, a pressure measuring device 6 for detecting the pressure of the gas flowing through the gas hole 12, and a sealing material 4 made of an elastic material disposed around the gas hole 12. Equipped.
[Selection] Figure 1

Description

  The present invention relates to a pressure loss measuring device for a ceramic honeycomb filter and a measuring method thereof.

  Exhaust gas mainly emitted from diesel engines contains unburned components (soot) such as unburned carbon and SOF (soluble organic components), and its harmfulness has been pointed out in recent years. For this reason, environmental regulations have become stricter in recent years, and emission standards have been established for diesel engine vehicles. As a method for reducing the unburned components, a method in which a ceramic filter is mainly installed inside the exhaust pipe and the unburned components are physically removed has been generally adopted in addition to improving the fuel of the engine. This ceramic filter is called a diesel particulate filter (DPF), and generally has a honeycomb shape, and a plurality of gas flow paths are alternately sealed upstream and downstream to provide a filter function. Due to the characteristics of the material constituting the DPF, a cylindrical integrated product and a bonded product obtained by bonding a divided product (segment) with improved durability are used.

  Conventionally, as a method for measuring the pressure loss of the ceramic honeycomb filter, the pressure difference between the upstream and downstream of the DPF is measured when a predetermined amount of gas is flowed by sealing the outer surface of the filter in a pipe. (See Non-Patent Document 1)

FIG. 4 shows a conventional pressure loss measurement method.
The cylindrical sample 27 is loaded into a sample holder 23 with a lid. The sealing material 25 requires two kinds of seals, that is, a seal between the sample 27 and the sample holder 23 and a seal between the sample holder 23 and its lid 24.

  If there is a leak, air that does not pass through the sample 27 is measured, so that a pressure loss value lower than the true pressure loss value is measured. Therefore, in order to perform accurate measurement, the sample 27 and the sealing materials 25 and 26 must be brought into close contact with each other, but it is difficult to confirm the presence or absence of leakage from the outside. Further, when the size of the sample 27 is different, it is necessary to make adjustments such as replacing the sealing material in order to obtain an appropriate sealing property each time. When the size of the sample 27 is different, it is necessary to match the amount of air per unit volume or per unit filtration area, and it is necessary to adjust the amount of air after measuring the size of the sample 27 each time.

  As described above, the conventional pressure loss measuring apparatus is required to set the filter in the holder in the pipe every time it is measured or to set the filter while sealing the outer periphery of the filter. In general, an organic sealant such as rubber or sponge is used for the seal, but since it is housed in the pipe, it cannot be visually confirmed whether the seal is made securely, and the seal is incomplete. In some cases, an error may be included in the measurement result of the pressure loss due to a gas leak from the seal portion. In particular, in the case of a prismatic segment, it is difficult to seal compared to a cylindrical integrated product, and leakage often occurs. Further, as described above, the seal is required to perform both a seal between the outer surface of the filter and the inner surface of the pipe and a seal inside and outside the pipe for taking the filter into and out of the pipe, which is structurally difficult.

  Furthermore, when the pressure loss is confirmed as a means of quality control, especially in the manufacturing process, the dimensions of the segment or the integral product may change due to variations in manufacturing conditions and manufacturing convenience. For comparison, it is necessary to match the flow rate per unit volume of the sample or the flow rate per unit filtration area, that is, the unit flow rate, and it is necessary to calculate the flow rate after measuring the sample size in advance. It took time and effort.

  Further, the ceramic filter is likely to be non-uniform due to its manufacturing method, and there are many variations in pressure loss depending on the location of the sample. In the case of the prior art, the difference in pressure loss depending on the location of the sample cannot be measured, and only the pressure loss as an overall average is obtained.

N. Taoka, et, al. “Effect of SiC-DPF with High Cell Density for Pressure Loss and Regeneration“ SAE Paper 2001-01-0191

  An object of the present invention is to solve these problems of the prior art, and is to simplify the setting of a sample. Another object is to reduce errors due to seal uncertainty, and Another objective is to reduce the effort of setting the flow rate depending on the sample size, and yet another objective is to measure the value of the pressure loss depending on the sample location so that the variation in quality depending on the sample location can be grasped. Is to make it.

  Accordingly, an object of the present invention is to provide a pressure loss measuring method and a measuring apparatus for a ceramic honeycomb filter that can ensure sealing performance with a simple configuration and can easily and reliably measure the pressure loss of a sample.

  The invention of claim 1 includes a gas source for measuring pressure loss of a sample, a sample holder in which a gas hole through which the gas flows is formed, a gas pipe connecting the gas source and the gas hole, and the gas A flow rate measuring device for detecting the flow rate of the gas, a pressure measuring device for detecting the pressure of the gas flowing through the gas hole, and a sealing material made of an elastic material disposed around the gas hole. A pressure loss measuring device for a ceramic honeycomb filter is provided.

  The invention of claim 2 is characterized in that the opening area of the gas hole is smaller than the area of the honeycomb end face of the sample.

  The invention of claim 3 is characterized in that a stopper for the sealing material is provided around the gas hole so as to protrude from the sample holder.

  The invention of claim 4 is characterized in that the sample is held by pressing the honeycomb end face of the sample against the sample holder via the sealing material.

  The invention according to claim 5 is characterized in that the measurement is performed by changing the position of the gas hole with respect to the honeycomb end face of the sample.

  The invention according to claim 6 is characterized in that measurement is performed in a state where the sample is exposed to the atmosphere except for the sealing material pressing portion of the sample.

  In the present invention, a sample can be easily set, that is, pressure loss can be easily measured. Further, since the sample can be visually confirmed when it is set in the holder, the sample can be surely sealed, and the measurement accuracy can be improved. Moreover, since the range in which the gas flows is a portion separated by the sealing material, the range can be defined in advance. That is, the flow rate may be a constant value, and it is not necessary to set the flow rate after measuring the size of the sample in advance. In addition, if the range of the sample to be measured is narrowed in advance with respect to the area of the sample, the pressure loss can be measured at different positions in the same sample, and the variation of the pressure loss depending on the location of the sample can be measured. it can. In addition, there is no need to set the outside of the sample in the pipe, and measurement can be started by pressing the sample holder and the sample, making the equipment simple and compact, greatly reducing the cost of manufacturing the equipment. Can do. In addition, since the sample holder is small, it is possible to easily measure the pressure loss even at the site such as where the filter is installed.

  According to the first aspect of the present invention, since the sample is attached to the sample holder via the sealing material, the sample can be easily attached to the measuring apparatus with a simple configuration. Further, since the gas supply part for the sample is only the gas hole portion of the sample holder, the gas hole can be reliably sealed by surrounding the gas hole with a sealing material. Moreover, since it is only necessary to flow a gas at a constant flow rate through the gas hole regardless of the size of the sample, it is not necessary to set the flow rate according to the size of the sample, and measurement can be easily performed.

  According to the invention of claim 2, since the opening area of the gas holes is smaller than the area of the honeycomb end face, the quality variation depending on the location of the sample can be easily determined by changing the position of the gas holes in the honeycomb end face.

  According to the invention of claim 3, when the sample is pressed against the sample holder, the elastic deformation of the sealing material in the gas hole inner direction is restricted by the stopper, so that the opening area of the gas hole is always kept constant, Increased measurement reliability.

  According to invention of Claim 4, a sample can be easily set only by pressing a honeycomb end surface to the sample holder side and holding a sample.

  According to the invention of claim 5, the local quality of the sample can be easily identified by changing the position of the gas hole with respect to the honeycomb end face and measuring by flowing the gas.

  According to the invention of claim 6, since sealing is not necessary except around the gas hole, the sample can be set easily, the sealing performance is ensured, and the seal can be easily confirmed.

  As the gas source of the present invention, air pressurized by a blower or a compressor is generally used, but air such as a cylinder or a gas such as nitrogen may be used. The pipe connecting the gas source and the sample holder may be a so-called gas pipe or a flexible hose. As a means for measuring the gas flow rate, an orifice, a nozzle, a flow meter using a resistor such as a wire mesh having a flow resistance subjected to flow rate verification, or an electromagnetic flow meter may be used in the middle of the pipe. In order to control the flow rate measured by these flow meters to a predetermined flow rate, a valve is provided and adjusted in the pipe. If a so-called mass flow controller is used as a device for flowing a constant flow rate, it is easy to flow a constant flow rate even if the conditions of the gas source slightly change.

  Furthermore, the sample holder is determined depending on the shape and application of the sample to be measured. In the case of the DPF, it is generally preferable that the sample holder has a flat pressing surface and the gas hole formed by the pipe is formed at the center thereof. In order to define the range to be pressed and prevent leakage to the outside, a sealant made of sponge or rubber is pasted around the gas hole. If the thickness of the sealing material is too thin, the surface roughness of the sample cannot be absorbed and gas may leak, and if it is too thick, the sealing material will be crushed when crimped and the gas flow range will be narrowed. In general, the thickness is about 0.5 mm to 10 mm, preferably 1 mm to 3 mm. Further, the measurement surface of the sample is not necessarily a flat surface.

  For example, when measuring partial pressure loss from the outer surface of a cylindrical filter, a sample holder and a sealing material may be manufactured in accordance with the situation. As a method for measuring the gas pressure, a measurement seat for measuring the pressure may be branched into a pipe connected to the sample holder, and a manometer, a Bourdon type pressure gauge or the like may be connected thereto.

  The sample holder can be fixed, or if you can hold it, you can measure the pressure loss at any place by pressing the large fixed sample holder and measure the pressure loss at any place of installation. Can do.

  In order to measure the pressure loss, a gas having a predetermined flow rate is first flowed, and the measurement surface of the ceramic filter is pressed against the seal surface. In the honeycomb-shaped ceramics filter, it is pressed against the opening surface (honeycomb end surface) of the alternately sealed cells. Since the passage flow rate decreases and falls below the set value due to the passage pressure loss of the filter, the operation of flowing the prescribed flow rate again is performed. This is not necessary if the flow rate is controlled to flow a constant flow rate in advance. The pressure is measured after confirming whether or not gas has leaked from the sealing surface with sound and airflow. In general, the pressure used is a direct-reading type such as a manometer or a Bourdon tube type, or a strain gauge type that is displayed by electrically converting the pressure. When the pressure loss value is stable, the pressure loss value is read.

Examples of the present invention will be described below.
FIG. 1 shows the overall configuration of an embodiment of the present invention.
By pressing the sample 5 against the sealing material 4 installed in the sample holder 3 and flowing the amount of air defined by the mass flow controller 2, a predetermined amount of air flows in the area of the sample 5 defined by the sealing material 4. The pressure loss at this time can be measured by the manometer 6.

A sample 5 made of a ceramic honeycomb filter has honeycomb end faces 5 A and 5 B at both ends, and one honeycomb end face 5 A is mounted on the sample holder 3 via a seal material 4. A positioning stopper 9 is provided on the sample holder 3. The positioning stopper 9 is formed, for example, in a V shape or a right-angled bending shape in a plan view, and presses and positions a cylindrical or quadrangular prism sample.
The ceramic honeycomb filter is formed of a sintered body such as Si ₃ N ₄ , SiC, or cordierite.

FIG. 2 illustrates the relationship between the sample holder and the sample according to the present invention in more detail. In this example, the sample 5 has a rectangular pillar honeycomb structure having a side of 57 mm and a length of 152 mm. The surface (honeycomb end surface) where the honeycomb opens is sealed with one of the communicating cells with a plug 14, and the adjacent cell seals the opening on the opposite side in the longitudinal direction of the cell. The sample holder is obtained by attaching a flange (disc) having an outer diameter of about 80 mm to an iron gas pipe 10 having an inner diameter of about 25 mm. A branch pipe 13 for measuring differential pressure is attached to the piping side of the flange, and is connected to a differential pressure gauge (manometer) by a resin hose (not shown). The sealing material 4 is a closed-cell elastic rubber sponge having an inner diameter of 24.5 mm, an outer diameter of 40 mm, and a thickness of 3 mm. The sample is held by hand and pressed against the sealing material 4. At the time of measurement, air of 11.8 m ³ / h is blown from the mass flow controller 2 so that the air flowing in the axial direction as shown by the air flow F flows through the wall surface to the adjacent cell and flows out from the opposite side of the honeycomb. .

  A gas hole 12 is formed in the center of the sample holder 3, and the gas pipe 10 is fixed through the gas hole 12. The upper end portion of the gas pipe 10 protrudes from the upper surface of the sample holder 3 to form a stopper 11 for the sealing material 4. When the sample 5 is pressed against the sample holder 3 by the stopper 11, the elastic deformation of the sealing material 4 in the inner direction of the gas hole 12 is restricted. Therefore, the opening area of the gas hole 12 is always kept constant.

FIG. 3 shows the measurement method of the present invention.
The measurement part for sample 5 (the part where gas is blown through gas hole 12) is moved to C0 to C5, and the pressure is measured. Thereby, as shown to (B), the dispersion | variation in the local quality by a place can be discriminate | determined.

  As described above, according to the present invention, it is possible to examine a variation in pressure loss depending on a measurement position, that is, a variation in quality. With the apparatus of the Example, the pressure loss of the ceramics filter by the honeycomb of diameter 143.6mm and length 152mm was measured. The measurement range is φ26 mm, and shows the pressure loss when the center is measured and when the measurement position is shifted toward the outer periphery by 10 mm from the center. As a result, in the case of this ceramic filter, it can be seen that the pressure loss gradually increases toward the outer peripheral side. This revealed the non-uniformity of performance depending on the location of the ceramic filter. If you want to investigate the difference in pressure loss depending on the location, as in this case, you can reduce the measurement range. Conversely, when this is not necessary, the entire measurement can be performed by increasing the measurement range.

  The present invention can be used as a measuring means for inspecting the quality of a product at the time of manufacturing a DPF.

The whole block diagram of the Example of this invention. The principal part block diagram of the Example of this invention. Explanatory drawing of the measuring method which concerns on this invention. The block diagram of the conventional pressure loss measuring apparatus.

Explanation of symbols

1: pressure reducing valve, 2: mass flow controller, 3: sample holder, 4: sealing material, 5: sample, 5A, 5B: honeycomb end face, 6: differential pressure gauge, 9: positioning stopper, 10: gas pipe, 11: stopper, 12: Gas hole, 13: Branch pipe, 14: Sealing.

Claims (6)

  A gas source for measuring a pressure loss of a sample, a sample holder in which a gas hole through which the gas flows is formed, a gas pipe connecting the gas source and the gas hole, and a flow rate measurement for detecting a flow rate of the gas A pressure loss measurement of a ceramic honeycomb filter, comprising: a device; a pressure measuring device for detecting a pressure of a gas flowing through the gas hole; and a sealing material made of an elastic material disposed around the gas hole. apparatus.   The pressure loss measuring device for a ceramic honeycomb filter according to claim 1, wherein an opening area of the gas hole is smaller than an area of a honeycomb end face of the sample.   The pressure loss measuring device for a ceramic honeycomb filter according to claim 1 or 2, wherein a stopper for the sealing material is provided around the gas hole so as to protrude from the sample holder.   The pressure loss measuring method of the ceramic honeycomb filter using the pressure loss measuring apparatus according to any one of claims 1 to 3, wherein the sample end face is pressed against the sample holder via the sealing material to hold the sample.   The pressure loss measurement method for a ceramic honeycomb filter using the pressure loss measurement apparatus according to claim 2, wherein the measurement is performed by changing the position of the gas hole with respect to the honeycomb end face of the sample. The method for measuring a pressure loss of a ceramic honeycomb filter according to claim 4 or 5, wherein measurement is performed in a state where the sample is exposed to the atmosphere except for the portion where the seal material is pressed.

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