JP3437918B2 - Gas analyzer heating probe - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a heating probe for a gas analyzer.

[0002]

2. Description of the Related Art Conventionally, when a sample gas such as an exhaust gas of an automobile engine is analyzed, the sample gas is sampled by measuring it by inserting a probe into a cylinder of the engine. It is possible to detect the state of gas in, and it is possible to perform more detailed measurement.

For example, in recent years, in a cylinder of an automobile engine, gas existing near a valve or near a spark plug is sampled using a capillary tube, and the gas is analyzed to measure the engine performance. It is also possible. Since this capillary is to take a sample gas from a location not violent pressure fluctuations, the capillary inner diameter is very small, and by a means such as silver brazing or welding so as to connect communicating at one end into the cylinder It is fixed. In addition, the capillary is not connected in the middle to prevent the buffer from being generated in the sample flow path,
It has a continuous and constant length.

When measuring a sample gas containing hydrocarbon, for example, a stainless steel pipe heated to about 190 ° C. is used as a sample flow path,
More stable gas analysis can be performed. Therefore, by using a heating probe coated with a heater on the outer circumference of a pipe for collecting a sample gas containing a gas such as hydrocarbon that should be kept at a high temperature, a specified temperature is kept.

[0005]

However, when one end of the capillary tube is welded to a fixed point such as a cylinder to form a probe as described above, in order to change the sample gas sampling point, another analyzer is used. It was necessary to reconnect to the heating probe. Therefore, when a heater is attached around the capillary tube as in the conventional case, since the capillary tube forming one end of the heating probe is fixed at the sampling point of the sample gas, not only the capillary tube but also the outer circumference of this capillary tube is fixed. The attached relatively expensive heater also needed to be removed from the gas analyzer. In other words, it is not economical because it is necessary to separately process each of the connected capillary tubes by a process called a hot hose and attach a heater.

Further, since a general method of connecting metal pipes is carried out by caulking each other with a metal joint, it is impossible to make a change such as separating the heating probe once assembled again. It was inconvenient.

The present invention has been made in consideration of such circumstances, and it is possible to easily change the measurement point even in the case of a gas analyzer probe which requires heating and whose one end side is fixed. It is an object of the present invention to provide a heating probe for a gas analyzer that can change measurement conditions.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and includes a capillary tube which is connected to an engine cylinder to collect a sample gas, and a heating tube into which the capillary tube is inserted. A pipe, a pipe joint portion for holding the heating pipe in a state in which the capillary is inserted, and further, a pipe joint portion for separably connecting to the capillary, and a capillary pipe arranged on the outer circumference of the heating pipe to heat the heating pipe. And a heater for keeping the temperature of the sample gas taken out constant.

Therefore, in the heating probe of the gas analyzer of the present invention, the heating pipe and the heating heater for heating are formed by separate members which are separable from the capillaries serving as the sample flow paths, so that only the inner capillaries are provided. It can be easily replaced according to usage conditions. In other words, due to the relocation of the gas analyzer and the change of the measurement point, the relatively expensive gas analyzer and heating pipe were separated while leaving only the capillary tube fixed at the measurement point and fixed at another measurement point. Can be connected to a capillary tube.

Therefore, even if there are a plurality of measurement points, the capillary tube can be heated by one heating pipe, which is economical. Further, since the conditions such as the thickness of the capillary and the material can be easily changed according to the measurement point and the condition of the sample gas, various flow rates and kinds of sample gas can always be optimally analyzed.

Further, the pipe joint portion is made of a synthetic resin which does not adsorb the sample gas and has excellent heat resistance, and the pipe joint in which the downstream end of the heating pipe is connected to one end side. Spacer resin fitted so as to circumscribe the downstream end of the capillary tube in a state where the pipe joint is covered with the capillary tube, and strong pressure is applied to the other end side of the pipe joint by the cap nut in the state of being circumscribing the spacer resin. The spacer resin may be composed of a resin ring for connecting to the other end of the pipe joint. In this case, since the capillary tube can be connected to the metal joint without caulking, it is possible to easily change the capillary tube by changing the measurement condition, that is, the measurement point.

Further, when the spacer resin is made of a fluorine-based resin, not only gas leakage between the spacer resin and the capillary tube can be prevented, but also the heat resistance is excellent and, for example, hydrocarbon or the like is used. Adsorption of the adsorptive gas can be effectively suppressed.

[0013]

1 to 3 show an engine 1 as an example.
An example in which an example of the heating probe 1 of the gas analyzer of the present invention is used as the heating probe 1 for collecting gas at measurement points A and B (illustrated only in FIG. 2) provided in the cylinder 11 of 0 is shown. .

In these figures, the heating probe 1 of this embodiment is connected to measurement points A and B in communication with a capillary tube 2 for collecting a sample gas, and a heating pipe 3 for inserting the capillary tube 2.
The heating pipe 3 includes a pipe joint portion 4 for holding the capillary tube 2 inserted therein, and a heater 5 arranged on the outer periphery of the heating pipe 3. Then, the downstream end of the heating probe 1 is connected to the gas analyzer 7 through the sample flow path 6 on the downstream side, and the gas state at the measurement point A can be measured.

The capillary tube 2 has, for example, an inner diameter of 0.4 mm,
One end of a stainless steel tubular body having an outer diameter of 1 mm and a length of 400 mm is fixedly provided on the engine 11 by adhering one end to a groove formed in the cylinder 11 or connecting it through a joint 12 or the like. Heating pipe 3 has an inner diameter of 2
It is a stainless steel tubular body having an outer diameter of 3 mm and an outer diameter of 3 mm, and the heater 5 is brought into close contact with the outer periphery of the tubular body by applying a process called a hot hose.

The heating heater 5 is connected to a power source (not shown) to heat the heating pipe 3 and the capillary tube 2 inserted in the heating pipe 3 to collect, for example, hydrocarbon as a sample gas. The temperature is adjusted to the optimum temperature of 191 ° C.

In the heating probe 1 of the gas analyzer of the present invention, the capillary tube 2 and the heating pipe 3 are separably connected by the pipe joint portion 4. Therefore, only the capillary tube 2 located inside is heated by the heating pipe 3 and the heater 5. Can be exchanged separately according to the usage conditions. That is, the measurement point A of the gas analyzer 7 is changed to the measurement point B, for example.
To move to the heating probe, the capillary tube 2 connected to the measurement point A is removed from the heating pipe 3 or the heater 5 and, instead, another capillary tube 2 connected to the measurement point B is inserted. Gas analyzer 7 by forming 1
Can be relocated.

The material of the capillary tube 2 thus changed can be appropriately changed according to the condition of the sample gas to be measured, and the thickness of the capillary tube 2 can be appropriately changed. Even if the type of the capillary tube 2 is changed, a different heating probe is used. Heating pipe 3 to form 1
It is economical because the heater 5 and the heater 5 can be commonly used.

The structure of the pipe joint portion 4 is clearly shown in the sectional view of FIG. That is, the pipe joint portion 4 of the present example includes at least the pipe joint 8, the spacer resin 9, and the resin ring 9 a circumscribing the spacer resin 9.

The pipe joint 8 has, for example, an outer diameter of 3 mm at both ends.
Of the heating pipe 3 is provided with a cap nut 8a, 8b for tightening on both sides thereof, and a downstream end portion of the heating pipe 3 is formed on one end side thereof and a taper portion is formed on the outer periphery thereof. It is fixed by tightening with the cap nut 8b via the ring 8c. Since the heating pipe 3, the pipe joint 8, the cap nut 8b, and the ring 8c of this example are all made of stainless steel, by tightening the cap nut 8b, the heating pipe 3 and the pipe joint 8 are caulked and cannot be separated. Become.

The spacer resin 9 is made of a fluorine-based resin as an example of a synthetic resin which does not adsorb a sample gas such as hydrocarbon and has excellent heat resistance, and is fitted so as to be circumscribed on the downstream end of the capillary tube 2. In this example, the outer diameter is 3 mm and the inner diameter is 1 mm. The resin ring 9a circumscribing the spacer resin 9 is made of the same fluorine resin as the spacer resin 9,
It is a ring body having an inner diameter of 3 mm and an outer diameter of 5 mm. The spacer resin 9 and the resin ring 9a made of a fluorine-based resin have a heat resistance of 200 ° C. or higher and do not adsorb hydrocarbon as a sample gas, so that the capillary tube 2 heated to about 190 ° C. can be sufficiently held and It does not adversely affect gas analysis.

Then, with the ring body 9a being positioned on the outer periphery of the upstream end of the spacer resin 9, it is pressed against the other end of the pipe joint 8 by a cap nut 8a made of, for example, graphite. At this time, the ring body 9a is elastically deformed so as to bite into the spacer resin 9, and the spacer resin 9 is strongly pressed so as to be sandwiched by the deformed ring body 9a. In this way, the spacer resin 9 can be connected to the downstream end of the capillary tube 2.

As in the above-mentioned example, by holding the capillary tube 2 in the heating pipe 3 by the spacer resin 9 made of synthetic resin and the ring body 9a, the capillary tube 2 can be fixed without caulking the metal pipe joint 8. Can be connected. Therefore, the capillary tube 2 can be easily removed according to the change of the measurement condition, and the change of the measurement point can be facilitated.

In the above example, the concentration value of hydrocarbon is measured from the measurement points A and B in the cylinder of the automobile engine as an example of the sample gas, but the present invention is not limited to this. Instead, it may be used to measure any other sample gas. Further, the temperature of the sample gas adjusted by the heater 5 can be set appropriately. Moreover, not resin as a material of the spacer resin 9 and the ring member 9a is limited to fluorine-based resin when the temperature is low, a resin having the requisite heat resistance, there in resin by adsorption of the sample gas It goes without saying that it can be used.

In the above example, the heating pipe 3 and the pipe joint 8
Connection with the ring 8c by tightening the cap nut 8b.
However, the present invention is not limited to this. For example, the heating pipe 3 and the pipe joint 8 may be connected by silver brazing or the like. Further, a flange is formed at the downstream end of the heating pipe 3 to allow the capillary tube 2
The heating pipe 3 and the capillary tube 2 may be removably attached by screwing the cap nut 8a to the flange with the spacer resin 9 and the ring body 9a attached to the downstream end of the.

[0026]

As described above, according to the heating probe of the gas analyzer of the present invention, the heating pipe for heating the sample gas and the heater are constituted by separate members which can be separated from the capillary which becomes the sample channel. Therefore, only the inner capillary can be easily replaced according to the usage conditions. That is, the conditions such as the thickness of the capillary tube and the material can be easily changed according to the conditions such as the measurement point, the type and flow rate of the sample gas, so that the sample gas under various conditions can always be analyzed in an optimal state. Further, due to the relocation of the gas analyzer and the change of the measurement point, the gas analyzer and the relatively expensive heating pipe can be separated while leaving only the capillary tube fixed at the measurement point. Therefore, when measuring another sampling point, it is not necessary to replace the metal joint and the heating pipe together with the capillary, and the heating pipe and the gas analyzer can be reused, which is economical.

In the case where the pipe joint portion is composed of a pipe joint, a spacer resin made of a synthetic resin which does not adsorb sample gas and is excellent in heat resistance, and a resin ring, a metal ring is used. Since the capillary tube can be connected to the joint without caulking, it is possible to easily change the capillary tube by changing the measurement condition, that is, change the measurement point.

Further, when the spacer resin is made of a fluororesin, it is possible not only to prevent gas leakage between the spacer resin and the capillaries, but also to have excellent heat resistance and to prevent the use of hydrocarbons or the like. Adsorption can be effectively suppressed.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of gas analysis using a heating probe of a gas analyzer of the present invention.

FIG. 2 is an exploded view of a heating probe of the gas analyzer.

FIG. 3 is a vertical sectional view showing a configuration of a pipe joint portion of a heating probe of the gas analyzer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Heating probe, 2 ... Capillary tube, 3 ... Heating pipe, 4 ... Pipe joint part, 5 ... Heater, 7 ... Gas analyzer, 8 ... Pipe joint, 8a ... Cap nut, 9 ... Spacer resin, 9a ... Resin ring , A, B ... Measuring points.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-9-133616 (JP, A) JP-A-8-114584 (JP, A) Actual development 5-33050 (JP, U) (58) Field (Int.Cl. ⁷ , DB name) G01N 1/00-1/44 JISST file (JOIS)

Claims (3)

(57) [Claims] 1. A capillary tube which is connected to an engine cylinder to collect a sample gas, a heating pipe into which the capillary tube is inserted, the heating tube in a state where the capillary tube is inserted, and the capillary tube is separated. A gas characterized by having a pipe joint portion for enabling connection, and a heating heater which is arranged on the outer circumference of the heating pipe to keep the temperature of the capillary and the sample gas sampled by heating the heating pipe constant. Analyzer heating probe. 2. The heating pipe, wherein the pipe joint portion is made of a synthetic resin that does not adsorb sample gas and has excellent heat resistance, and a pipe joint in which the downstream end of the heating pipe is connected to one end side. Spacer resin fitted so as to circumscribe the downstream end of the capillary tube with the pipe joint covered with the capillary tube, and strong pressure on the other end side of the pipe joint by the cap nut in the state of being circumscribed with the spacer resin. The heating probe of the gas analyzer according to claim 1, further comprising a resin ring for connecting the spacer resin to the other end of the pipe joint according to. 3. The heating probe for a gas analyzer according to claim 2, wherein the spacer resin is made of a fluorine resin.