JP5513208B2 - Piping surface multipoint temperature sensor and flow measurement pipe - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a pipe surface multipoint temperature sensor that can be easily mounted in various surface diameters in the surface temperature measurement in the pipe cross-sectional direction, and a pipe for flow rate measurement in which the pipe surface multipoint temperature sensor is attached to the surface. Is.

As a technique for easily and inexpensively measuring the flow rate of a fluid flowing in a pipe, there is a “flow rate measuring method” that the applicant previously proposed (Patent Document 1). In this measurement method, two temperature sensors are installed at a certain distance on the pipe surface, and the flow rate in the pipe is calculated from the time difference between the temperature waveforms obtained by the respective temperature sensors. A pipe surface temperature sensor is used as a temperature sensor used in this measurement method, and it is necessary to satisfy the following conditions.
・ Small time constant and excellent response to temperature change (captures even minute temperature changes).
・ Insensitive to ambient temperature.
・ Easy attachment and detachment regardless of measurement conditions (pipe material, pipe diameter, etc.).
・ There is little variation in detection sensitivity.

  As a surface temperature sensor that satisfies the above conditions, there is a so-called film type temperature sensor. This temperature sensor has a very small heat capacity because the sensor element is a thin plate, and has a certain degree of flexibility. Therefore, the responsiveness to a temperature change is extremely excellent, and it is possible to reliably adhere to a pipe having a curved surface. Thereby, variation in the detection sensitivity with respect to the temperature change of each temperature sensor when attached to the pipe surface can be suppressed, and the response speeds of the two temperature sensors can be made substantially the same. Further, it is easy to keep the temperature around the sensor unit, and the effect of the ambient temperature can be reduced by carrying out the temperature keeping, and highly accurate measurement is possible.

  By the way, the “fluid flow”, “swirl flow” and the like are generated in the fluid flowing in the pipe. This is a phenomenon that occurs when fluid is disturbed by piping joints such as elbows and valves, and devices such as pumps. When this phenomenon occurs, for example, even if a temperature sensor is attached at the same distance from the elbow, the measurement direction (up / down / left / right) differs with respect to the pipe cross-section, resulting in a deviation in the timing of temperature change. .

  The inventors have actually measured the pipe surface temperature in the upward and downward direction of the pipe at the same distance from the elbow for a cooling water pipe having a diameter of 100A (pipe material is white gas pipe). The result shown in FIG. 10 was obtained. According to these temperature waveforms, it can be confirmed that the temperature sensor installed in the upward direction of the pipe is reacting faster than the temperature sensor installed in the downward direction. This is because the pipe surface temperature is measured because the heat is transferred from the fluid in the pipe to the pipe, and the heat is transferred from the pipe to the temperature sensor.When the heat is transferred from the fluid in the pipe to the pipe, the flow of the fluid in the pipe is measured. The situation is thought to be affecting. That is, for example, when the main flow of the flow meanders up and down and left and right in some parts, while the side flow of the flow forms vortices in other parts, the influence of the influence causes the pipe up and down and left and right. There is a difference in reaction time depending on the direction.

  As described above, if the measurement direction is different from the pipe cross section and the temperature change occurs, the time difference between the two points from the pipe surface will be measured and the flow rate will be calculated. The time difference of temperature change between two points, which is the most important in the “method”, cannot be measured accurately.

  To solve this problem, a method can be considered in which the influence of the temporal shift of the temperature change (temperature waveform) caused by the measurement direction is reduced by increasing the distance between the two temperature sensors installed on the pipe. It is done. This is a method utilizing the fact that if the distance between two temperature sensors is increased, the time difference obtained in proportion to the distance is also increased, and the contents thereof will be described below.

  For example, when the measurement conditions are a pipe flow velocity of 1 m / s and a sensor distance of 10 m, the theoretical time difference generated between the two temperature sensors is 10 seconds. Here, in the temperature sensor installed on the upstream side and the temperature sensor installed on the downstream side, a time shift occurs depending on the installation direction with respect to the pipe cross-sectional direction. Assuming that the deviation shown in FIG. 10 is the maximum, this deviation is 4 seconds (± 2 seconds) when read from the figure, and the temperature sensor installed on the upstream side and the temperature installed on the downstream side It occurs equally on both sensors.

  Therefore, the time difference that may occur between the two points is doubled by 8 seconds (± 4 seconds). As a result, the time difference that may be measured under the above conditions is 6 seconds to 14 seconds, and the measurement accuracy at this time is 60% to 140%. On the other hand, the theoretical time difference when the in-pipe flow velocity is 1 m / s and the distance between the sensors is 20 m is 20 seconds. Here, the time difference that may occur between the two points is 8 seconds (± 4 seconds), so the time difference that may be measured is 16 to 24 seconds, and the measurement accuracy is 80% to 120%. As described above, by taking a long installation distance between the sensors, it is possible to reduce the influence of the temporal deviation that occurs depending on the direction in which the temperature sensor is installed.

  Here, the above example is a result of a trial calculation under the condition that the flow velocity in the pipe is fixed at 1 m / s, but naturally the flow velocity (flow rate) in the pipe also changes in actual measurement. The relationship between the time difference and the flow velocity is inversely proportional, and the influence of temporal deviation becomes larger as the flow velocity becomes faster, and the influence of temporal deviation becomes smaller as the flow velocity becomes slower. From the above, simply taking a long distance between the two temperature sensors makes it impossible to measure with stable accuracy due to the influence of the flow velocity.

  In addition, there is a method of coping with the direction of installation of the temperature sensor with respect to the pipe cross-section direction (for example, when a temperature sensor installed on the upstream side is installed in the upper direction of the pipe, the temperature sensor installed on the downstream side is also installed on the pipe. Etc.). However, the degree of change (change order, time, etc.) shown in FIG. 10 is based on the state of the flow of fluid flowing in the pipe, that is, the way of assembling the pipe on the upstream side of the location where the temperature sensor is installed and the situation of the pipe inner surface. Changes due to (such as rust). Accordingly, the result obtained every time the measurement conditions change, such as moving the measurement location, changes, and the temperature sensor installed on the upstream side and the temperature sensor installed on the downstream side do not always react in the same manner. Therefore, unifying the installation direction of the temperature sensor does not lead to measurement with stable accuracy.

  From the above, if a film-type temperature sensor is used to measure the temperature of the previously proposed “flow rate measurement method”, the film-type temperature sensor becomes a “point” measurement with respect to the pipe cross section. The result (waveform) varies depending on the location where the temperature sensor is installed, and reliable measurement is not possible.

  Therefore, as a method for solving the above problems and performing measurement with stable accuracy regardless of changes in measurement conditions, the average temperature in the pipe cross-section direction, that is, the temperature in the pipe cross-section direction at a certain point, is continuously applied to the peripheral surface. A method for measuring the average temperature when measuring once along the line is conceivable.

  In addition, in order to precisely measure the average temperature in the pipe cross-section direction as described above, for example, by measuring (photographing) the entire circumference of the pipe cross-section using a thermo camera or the like and processing the measurement data A method of specifying the average temperature in the pipe cross-sectional direction is also conceivable. However, in this method, the measuring instrument becomes expensive and post-processing after measurement takes time, which is not practical.

  Therefore, as a method of measuring the temperature close to the average temperature in the pipe cross-section direction, a plurality of temperature sensors are installed along the pipe cross-section, that is, along the circumference of the pipe at right angles to the axial direction of the pipe. A method of averaging the measured temperature data and setting the average temperature of the plurality of temperature sensors as the average temperature in the pipe cross-sectional direction at that point can be considered (Patent Document 2).

JP-A-2005-291766 Japanese Patent Laid-Open No. 7-306097

  However, in the conventional method described above, it is necessary to install a plurality of temperature sensors on the pipe surface, and it takes time and effort to attach the temperature sensor. Further, it is necessary to perform wiring from each temperature sensor to the recorder, and in particular, wiring at the measurement location and around the recorder becomes complicated. Furthermore, if you try to measure the temperature as close as possible to the actual average temperature in the pipe cross-section direction, you can respond by increasing the number of equal fractions in the pipe cross-section direction. A recorder capable of recording the sensors and the number of installed temperature sensors is required. Moreover, when installing each temperature sensor with respect to a pipe cross section, an individual difference will arise in the uniformity of arrangement | positioning. If it becomes like this, the advantage which can measure flow volume simply and cheaply from the piping surface which is the big characteristic of the above-mentioned "flow measurement method" will be lost.

On the other hand, there is a measurement method as shown in FIG. 11 as a method of measuring the average temperature at a plurality of measurement points. In this measurement method, as shown in FIG. 11, the “+ legs” of the “+ legs” of the thermocouples 101, 102, 103 are taken out from the “+” terminals of the recorder 104. The “−leg” strands 101 b, 102 b, and 103 b of the thermocouples 101, 102, and 103 are connected to the “−leg” strand 106 taken out from the “−” terminal of the recorder 104. How to connect. By connecting in this way, each thermocouple 101, 102, 103 is arranged in parallel to the recorder 104, and between the terminals of the recorder 104, each thermosensitive part (the black circle part in FIG. 11). ) Of the electromotive force (E ₁ , E ₂ , E ₃ ) is generated (see the equivalent circuit in FIG. 12). As a result, the recorder 104 measures the average temperature of these heat sensitive parts.

  If the measurement method shown in FIGS. 11 and 12 is used, the wiring around the recorder 104 can be simplified. In addition, since the average temperature of the heat sensitive part is recorded in the recorder 104, post-processing after measurement is not necessary. Furthermore, the connection points of the strands 105 and 106 taken out from the recorder 104 and the strands 101a, 102a and 103a and the strands 101b, 102b and 103b of the thermocouples 101, 102 and 103 (white circles in the figure) ), The number of thermocouples can be increased / decreased in accordance with the number of measurement points.

  Here, the thermocouples 101, 102, 103 of FIG. 11 are joined to the + leg wires 101a, 102a, 103a and the-leg wires 101b, 102b, 103b. It is a “point”. Therefore, when measurement is performed using the thermocouples 101, 102, 103 of FIG. 11, in order to avoid the influence of the ambient temperature due to heat conduction from the wiring, of course, each heat sensitive part is surely adhered to the pipe surface. The wiring leading to the heat sensitive part must also be in close contact with the pipe surface to a certain length. The influence of the ambient temperature due to heat conduction from the wiring is a phenomenon that occurs when heat is transmitted through the wiring (metal thermocouple wire), so it cannot be eliminated even if heat is kept around the heat sensitive part. Contact is important.

  In such a case, strict specifications according to the measurement environment are required, and this may cause individual differences during installation. In addition, in order to bring the measured average temperature of the heat-sensitive part close to the average temperature in the pipe cross-sectional direction, each heat-sensitive part should be as far as possible in the pipe longitudinal direction and in the pipe cross-sectional direction (pipe circumferential direction). It is necessary to arrange evenly. However, if this is the case, it is premised that a hand or head can enter the work in the entire circumferential direction of the pipe cross section, and if the pipes are in close contact with each other, the installation work becomes difficult. From the above, as a result, the thermocouples 101, 102, and 103 shown in FIG. 11 do not lead to elimination of labor and individual differences in mounting and simplification of wiring at measurement points.

  The present invention has been made in view of the above points, and when measuring the surface temperature of a pipe with a temperature sensor, it eliminates the trouble and individual differences in mounting of the sensor, and wiring around the measurement location. The purpose is to simplify.

In order to achieve the above object, the present invention is a temperature sensor that is attached to a pipe surface and measures the temperature of the pipe surface, and is made of a conductive material having a property of becoming a + leg in a thermocouple element, and has a certain length. The anode part and the cathode part having a fixed length made of a conductive material having the property of being a leg are alternately joined so that one end serves as the anode part and the other end serves as the cathode part as a whole. Are connected in series, and the anode part and the cathode part are in the form of a thin plate exposed so as to be in close contact with the pipe surface , and a heat-sensitive part is constituted by the joined part of the anode part and the cathode part, and the anode part and the cathode part The connected body forms a band-shaped heat-sensitive assembly band, and the anode part and the cathode part located at both ends are respectively connected to the wire connected to the wiring connection terminal connected to the measuring device. Yes.

  The basic configuration of the present invention is schematically shown in FIG. That is, this prepares a plurality of thermocouples shown in the figure, for example, thermocouples 1a to 1e, and alternately turns the + leg 2 and the-leg 3 of the strands of each thermocouple 1a to 1e, that is, For example, the + leg 2 of one thermocouple 1b and the + leg 2 of another adjacent thermocouple 1c are joined to the-leg 3 of one thermocouple 1a and the-leg 3 of another adjacent thermocouple 1b. Is. This is schematically shown in FIG.

When the + leg 2 and the-leg 3 are alternately joined as described above, the + leg 2 is arranged on the left side and the-leg 3 is arranged on the right side in FIG. In the thermosensitive portion 4 (black circle portion), “positive” electromotive forces (E ₁ , E ₃ , E ₅ ) are generated. Conversely, “negative” electromotive force (−E ₂ , −E ₄ ) is generated in each thermosensitive portion 4 of the thermocouples 1 b and 1 d in which the −leg 3 is disposed on the left side and the + leg 2 is disposed on the right side.

  FIG. 3 shows an equivalent circuit of the “series thermocouple” shown in FIGS. As can be seen from FIG. 3, the electromotive force E generated at both ends of the wiring is the difference between the “total value of positive electromotive force” and the “total value of negative electromotive force”. The electromotive force E can obtain a temperature close to the average temperature of the heat sensitive parts when the temperatures of the heat sensitive parts 4 are substantially the same.

  The present invention is based on such a principle, and will be described with reference to FIG. 1. When a thermocouple element is configured, the anode portion of the conductive material having the property of becoming a + leg is adjacent to the + leg 2. The cathode part made of a conductive material having the property of being a leg corresponds to a combination of the adjacent leg 3 and the leg 3, and an anode part and a cathode part. The joint part corresponds to the heat-sensitive part 4. Therefore, by attaching the temperature sensor of the present invention to the peripheral surface of the pipe to be measured, the heat sensitive parts are annularly arranged on the peripheral surface of the pipe at regular intervals, and the temperature at each equidistant point is measured. can do. And the average temperature can be measured by connecting the wire connected to the anode part and the cathode part located at both ends to the wiring connection terminal connected to the measuring device.

  Although details will be described later, the length of the anode part and the cathode part is preferably 20 mm.

  Further, in view of various lengths of the outer periphery of the tube (that is, the diameter of the tube), an extension unit is provided as necessary, and the extension unit is formed by alternately joining the anode part and the cathode part. As a whole, odd-numbered pole portions are connected in series, and the pole portion located at one end of the extension unit is provided with a connecting strand connected to the strand, and the pole portion located at the other end of the extension unit It can be proposed that an element wire connected to the wiring connection terminal is provided.

  It is also possible to embody a pipe surface multipoint temperature sensor as described above as a flow rate measuring pipe by previously attaching the pipe surface multipoint temperature sensor in a ring shape in a direction perpendicular to the axis of the pipe.

  According to the present invention, it is possible to reduce labor and individual differences in attachment, and simplify wiring of measurement locations.

It is explanatory drawing for demonstrating the principle of this invention. It is explanatory drawing for demonstrating the principle of this invention. It is explanatory drawing which shows the equivalent circuit of the temperature sensor shown in FIG. 1, FIG. It is explanatory drawing which showed typically the structure of the piping surface multipoint temperature sensor concerning embodiment. It is a perspective view which shows a mode that the piping surface multipoint temperature sensor of FIG. 4 was attached to piping which is a measuring object. It is a graph which shows the result of having installed the surface temperature sensor in eight directions with respect to the pipe section direction, and measuring pipe surface temperature. It is explanatory drawing which shows the condition of the pipe cross section which has uniform temperature distribution from 20 degreeC to 20.2 degreeC in 10 points | pieces of piping outer periphery. It is explanatory drawing which showed the structure of the extension unit typically. It is explanatory drawing at the time of using combining the pipe surface multipoint temperature sensor of FIG. 4, and the extension unit of FIG. It is a graph which shows the situation of the gap of the time which occurs to the pipe section direction when measuring the pipe surface temperature in the upper direction and the lower direction of the pipe at the same distance from the elbow. The method of connecting the + leg wire of the thermocouple to the + leg wire taken out from the + terminal of the recorder and connecting the-leg wire to the-leg wire taken out from the-terminal is schematically shown. FIG. It is explanatory drawing which shows the equivalent circuit of FIG.

  Hereinafter, a pipe surface multipoint temperature sensor according to an embodiment of the present invention will be described with reference to the drawings. FIG. 4 schematically shows the configuration of the pipe surface multipoint temperature sensor 11 according to the embodiment. In the embodiment, each of the plurality of anode portions P1 to Pn and the plurality of cathode portions N1 to Nn is thin plate-like, and the same number of each anode portion P and cathode portion N are joined alternately, and the pipe surface multipoint temperature is obtained. The entire sensor 11 has an even number of poles.

  The anode parts P1 to Pn and the cathode parts N1 to Nn are made of conductive materials having different thermoelectric power. That is, the anode parts P1 to Pn are made of a conductive material having the property of becoming a + leg in the thermocouple element, and are made of, for example, copper in the present embodiment. The cathode portions N1 to Nn are made of a conductive material having a property of being a leg in the thermocouple element, and are made of, for example, constantan in the present embodiment. In the present embodiment, the lengths of the anode part P and the cathode part N (left and right direction in the figure) are all the same and are set to 20 mm.

  The joined portion between the anode portion P and the cathode portion N constitutes a linear heat-sensitive portion 12. And the connection body of anode part P1-Pn and cathode part N1-Nn which have these heat-sensitive parts 12 forms the strip | belt-shaped heat-sensitive aggregate band 13. FIG. The anode part P1 is located at one end of the heat-sensitive assembly band 13, and the strand 14 is connected to the end part of the anode part P1. The wire 14 is connected to a wiring connection terminal 16 connected to the measuring device 15 shown in FIG. A cathode portion Nn is located at the other end of the heat-sensitive assembly band 13, and an element wire 17 is connected to the end portion of the cathode portion Nn. A wire connection terminal 18 connected to the measuring device 15 is connected to the element wire 17. Each of the strands 14 and 17 is made of a conductive material having the same thermoelectric power as the corresponding anode part P and cathode part N.

  The pipe surface multipoint temperature sensor 11 according to the embodiment has the above-described configuration. When the pipe surface temperature at a desired position of the pipe 20 is measured as shown in FIG. As shown in Fig. 2, the pipe 20 is wound in an annular shape along the peripheral surface of the position. Strictly speaking, as shown in the figure, the entire circumference of the pipe 20 is spirally displaced by shifting by the width of each anode part P (or the cathode part N) during one round of the pipe 20. Become. Thereafter, the wiring connection terminals 16 and 18 may be connected to the measuring device 15 in the same manner as a normal temperature sensor of this type to perform normal measurement.

  In this case, since the heat-sensitive part 12 which is the most end part is a joint part on the inner side by the length per one extreme part (a concept regardless of the anode part P or the cathode part) from the end of the heat-sensitive assembly band 13, The influence of the ambient temperature from the strands 14 and 17 side is canceled by the terminal anode part P and cathode part N in contact with the pipe 20, and the influence on the measurement value can be suppressed. Further, since the influence of the ambient temperature can be suppressed by bringing the heat-sensitive assembly band 13 into close contact with the pipe 20 to the end, standardization at the time of sensor attachment is also possible. That is, it is not necessary to pay attention to how many centimeters or more the wiring must be in close contact with the piping. Also, as shown in FIG. 5, the wiring around the sensor is very simple.

  The longer the length of each thin plate-shaped pole part constituting the heat-sensitive assembly band 13, the easier it is to connect the anode part P and the cathode part N, and the manufacture of the heat-sensitive assembly band 13 becomes easier. On the other hand, since the number of the heat sensitive parts 12 decreases, the temperature measurement becomes rough, and a difference easily occurs between the average temperature in the pipe cross-sectional direction and the measured temperature. On the contrary, if the length per sheet is shortened, the number of the heat sensitive parts 12 increases, so that the temperature measurement becomes finer, and the difference between the average temperature in the pipe cross-sectional direction and the measured temperature is less likely to occur. However, it takes time and cost to manufacture the heat-sensitive assembly zone 13 accordingly.

  Further, in order to measure the temperature as close as possible to the average temperature in the pipe cross-sectional direction, it is desirable to arrange the heat-sensitive part 12 evenly with respect to the pipe cross-section, but in the embodiment, the heat-sensitive collective band 13 is formed. Since the anode part P and the cathode part N have the same length, it is possible to measure a temperature very close to the average temperature in the pipe cross-sectional direction at this point.

  In addition, when attaching to the surface of the pipe 20, the heat-sensitive assembly band 13 is in the form of an elongated thin plate, so one end of the heat-sensitive assembly band 13 is fixed to the attachment location with tape or the like, and the pipe 20 along the heat-sensitive assembly band 13. If you trace the surface of your finger with your finger, the installation is complete. Therefore, it is very simple, and it is difficult for the difference in measurement results due to the difference in the mounting condition depending on the skill of the operator. And by attaching in this way, each electrode part which comprises the heat sensitive gathering zone 13 with each heat sensitive part 12, ie, the anode part P and the cathode part N, also closely_contact | adheres to the piping 20, and the influence of ambient temperature by heat conduction Can be suppressed. In addition, since the length of each pole portion is set to a certain length, there is no need to consider the equal arrangement in the pipe cross-sectional direction of the heat sensitive portion at the time of installation, and also in this respect, individual differences at the time of installation are eliminated. be able to. Furthermore, if the heat-sensitive assembly band 13 attached as described above is further fixed over the entire circumference with a tape or the like, it is possible to make it adhere more reliably over a long period of time. Further, the risk of disconnection of the sensor during the heat insulation work after the sensor is attached as necessary can be reduced, and furthermore, since each pole portion is thin, the heat insulation work is hardly hindered.

  As shown in FIG. 5, if a pipe 20 having a pipe surface multipoint temperature sensor 11 attached in an annular shape is prepared in advance, the pipe is constructed as a flow rate measuring pipe in the middle of the pipe construction. By doing this, it is possible to easily measure the temperature of the pipe surface even in a place where the pipe becomes congested, which is difficult to attach the pipe surface multipoint temperature sensor 11 after the completion of construction. .

  In the present embodiment, since both the anode part P and the cathode part N are set to a length of 20 mm, as described below, the temperature sensor is extremely versatile.

  That is, the relationship between the pipe diameter and the outer peripheral length of a commonly used air conditioning pipe (white gas pipe) is as shown in Table 1.

  From Table 1, the outer peripheral length of each pipe diameter is a multiple of about 40 mm, although there is some variation. That is, the outer peripheral length of each pipe diameter can be substantially equally divided by 40 mm. Here, if the length per one pole part is set to 40 mm, the aperture diameter becomes an odd number and the aperture diameter becomes an even number. For example, in the case of 100 A, when the outer peripheral length is calculated as 358.9 mm≈360 mm, the number of divisions becomes 9 when 360 mm is divided by 40 mm. Here, when the number of divisions is an odd number, both ends of the heat-sensitive aggregate band 13 are pole portions of the same pole. For example, when the number of divisions is 5, the arrangement of the poles is +-++-+, and both ends are + leg thermocouple elements, which can no longer serve as temperature sensors.

  In this respect, in the present embodiment, since the anode part P and the cathode part N whose length per one pole part is set to 20 mm are used, the outer peripheral length of any pipe diameter shown in Table 1 Even so, the number of divisions is an even number and is applicable.

  Strictly speaking, the outer peripheral length of each pipe diameter listed in Table 1 is not a multiple of 20 mm. Therefore, when the length per one pole portion is unified at 20 mm, a surplus portion is generated. Moreover, since the same strand as the pole part of the end part of the heat sensitive gathering band 13 is connected to the both ends of the heat sensitive gathering band 13 of the temperature sensor concerning Embodiment, the part enclosed by the ellipse of FIG. As a result, one point of the heat sensitive part falls off.

  However, as a result of verification by the inventors, it has been found that even if one point of the heat sensitive part falls off, there is almost no influence on the actual measurement result. Hereinafter, the verification result will be described.

  FIG. 6 shows the result of measuring the surface temperature of the pipe by installing surface temperature sensors in eight directions with respect to the pipe cross-sectional direction. The piping which measured was a cooling water piping, and a diameter is 150A. Note that the measurement direction is a cross-sectional direction when viewed in the direction in which water flows from the near side to the far side in the figure.

  For example, when performing flow rate measurement using Japanese Patent Application Laid-Open No. 2005-291766 previously proposed by the applicant, the flow rate is calculated from the time difference between the temperature changes captured by the upstream and downstream temperature sensors. In such a case, a condition required for this type of temperature sensor is that a temperature close to the average temperature in the pipe cross-sectional direction at the moment when the temperature change occurs can be measured. The temperature change here means that the temperature rises (decreases) from a certain temperature, or that the temperature that has risen (decreased) starts to fall (rise), and the temperature continues to rise, or In the state where it continues to decrease, it is unsuitable for specifying the time difference because it is affected by instrumental errors and the like.

  Based on the data in FIG. 6, among the times (12 to 18 seconds) in which the temperature change seems to have occurred in any measurement direction, “12 seconds”, “15 seconds”, and “18 seconds” Table 2 shows the measured values for each cross-sectional direction and the average values.

  When measuring the multipoint temperature on the outer periphery of the pipe using the pipe surface multipoint temperature sensor 11 according to the embodiment, as described above, one measurement direction for one point falls out. It changes with the attitude | position which attaches the piping surface multipoint temperature sensor 11. FIG. That is, it changes depending on the position at which the pipe surface multipoint temperature sensor 11 is wound around the pipe 20 and the end of the winding. Therefore, it is important that the value is almost the same as the average temperature of 8 points shown in Table 2 regardless of the direction in which the dropout occurs.

On the other hand, Table 3 shows values that are supposed to be instructed for each direction in which the temperature data is dropped if the pipe surface multipoint temperature sensor 11 according to the embodiment is used. The calculation method is as follows. That is, for example, when the upward direction falls off at 12 seconds, the following occurs.
31.54 + (− 31.53) +31.55 + (− 31.54) +31.52 + (− 31.53) + 31.52 = 31.53 (° C.)

  Next, Table 4 shows the difference between the values shown in Table 3 (calculated) and the measurement results shown in Table 2.

  According to this, the maximum difference from the eight average temperatures actually measured is 0.02 ° C. Here, the results in Table 4 are based on the assumption that the measurement was performed at seven points that were dropped by one point in the direction of the pipe cross section of 150A. On the other hand, when the pipe surface multipoint temperature sensor 11 in which the length per each pole portion is set to 20 mm is used, the number of measurement points is 25 points (see Table 5) in the 150 A pipe specification. Therefore, the above difference will be even smaller. Table 5 shows the length of the heat-sensitive assembly band when the length per one pole portion is set to 20 mm and the number of heat-sensitive portions for each pipe having a different diameter.

  Currently, the resolution of temperature recorders using commercially available thermocouples is generally 1/10 ° C, and the maximum is 1/100 ° C. There is no problem above.

  From another point of view, the maximum temperature difference generated with respect to the pipe cross-sectional direction is, for example, about 0.2 ° C. based on the measurement result shown in FIG. Here, of the pipe diameters described in Table 5 above, 50A having the smallest number of heat sensitive parts will be described as an example. For example, as shown in FIG. If it is assumed that a pipe cross section having a temperature distribution exists, the average temperature at this time is 20.1 ° C. In this case, according to the pipe surface multipoint temperature sensor 11 according to the embodiment, in the case of the pipe diameter 50A, since one point is missing, the number of the heat sensitive parts 2 is nine (Table 5).

  At this time, assuming that the highest temperature of 20.2 ° C. (measurement point in the downward direction in the figure) is missing, the average temperature in this case is 20.089 ° C., which is 20. An error of 0.011 ° C. occurs with 1 ° C. However, as described above, since the maximum resolution of a temperature recorder using this type of thermocouple is generally 1/100 ° C., this error is negligible compared to that. When the pipe diameter is larger than 50 A, the number of measurement points further increases (see Table 5), so that the “weight” per point is reduced, the influence is further reduced, and the error is reduced. Therefore, even from this point, even if one heat sensitive part is missing, there is no problem in practical use.

  In order to obtain the above accuracy, a pipe surface multipoint temperature sensor having a heat-sensitive aggregate zone twice as long as the outer circumference of the pipe to be measured may be used to wrap the pipe to be measured twice. Or, by wrapping two pipe surface multipoint temperature sensors around the pipe, for example, by shifting by 10 mm along the axial direction of the pipe, the number of measurement points can be increased, and more accurate measurement is possible. It becomes.

  Next, in Japanese Patent Application Laid-Open No. 2005-291766 (Patent Document 1), the inventors also examined the influence of the flow velocity in the pipe, which is a factor that affects the important time difference of the measurement difference. It was also found that the order in which the temperature changes occurred did not change. In other words, it was found that although there is some relationship between the deviation of the temperature change caused by the flow velocity and the measurement direction, the deviation is not greatly increased or shortened by the change of the flow velocity. . Considering that the flow velocity in general air-conditioning pipes is 1.5 m / s to 2.5 m / s, and at most 3.5 m / s, the flow rate varies depending on the measurement direction. It can be considered that the impact on Therefore, the present invention can measure a suitable pipe surface temperature without being substantially affected by changes in the pipe flow velocity.

  As a matter of course, if the pipe diameter changes, the pipe outer peripheral length also changes. In order to cope with the change in the pipe outer peripheral length, the pipe surface multi-point temperature sensor 11 having the heat-sensitive aggregate band 13 having a length corresponding to each pipe outer peripheral length is prepared for each pipe having a different diameter. There is room for economic improvement. Furthermore, if a pipe surface diameter to be measured is preliminarily investigated and a pipe surface multipoint temperature sensor having a heat-sensitive assembly zone 13 having a necessary length is prepared, it takes too much time for preparation and lacks responsiveness.

  In order to cope with such a problem, for example, the extension unit 21 shown in FIG. 8 can be used and combined with the pipe surface multipoint temperature sensor 11 serving as the basic unit as described above.

  The extension unit 21 has an anode part p made of the same size and material as the anode part P used in the pipe surface multipoint temperature sensor 11 and a cathode part n made of the same size and material as the cathode part N alternately. The odd-numbered pole portions as a whole are connected in series. In the example of FIG. 8, two cathode parts n1 and n2 and one anode part p1 are joined, and cathode parts n1 and n2 are located at both ends.

The cathode portions n1 and n2 at both ends are connected to strands 22 and 23 made of the same material as the strands 17 of the pipe surface multipoint temperature sensor 11 serving as a basic unit. A wiring connection terminal 24 suitable for the wiring connection terminal 18 of the surface multipoint temperature sensor 11 is connected, and the wire 23 having the same shape and size as the wiring connection terminal 18 of the pipe surface multipoint temperature sensor 11 is connected to the end of the strand 23. A connection terminal, that is, a wiring connection terminal 25 connected to the measuring device 5 is connected. In such an extension unit 21, two joint portions of two cathode portions n1 and n2 and one anode portion p1 constitute heat-sensitive portions 26 and 27, respectively.

  The extension unit 21 in FIG. 8 has the above-described configuration, and is used in combination with the pipe surface multipoint temperature sensor 11 serving as a basic unit as shown in FIG. That is, the wiring connection terminal 24 of the strand 22 at the end of the extension unit 21 is connected to the wiring connection terminal 18 of the strand 17 at the end of the pipe surface multipoint temperature sensor 11, and the extension unit 21 is connected to the piping surface multipoint. In parallel with the temperature sensor 11, the cathode part n1 at one end of the extension unit 21 and the cathode part Nn at the end of the pipe surface multipoint temperature sensor 11 are arranged in the same position in the circumferential direction. Install along the surface of the pipe.

  As a result, the heat-sensitive collective band is extended as much as the heat-sensitive portions 26 and 27 as a whole. Therefore, when only the pipe surface multipoint temperature sensor 11 cannot cover the entire circumference of the pipe, the surface temperature of the pipe can be measured by appropriately using the extension unit 21 together. In this case, by preparing a plurality of extension units 21 as a basic form, it can be applied to pipes of various diameters, and the pipe surface multipoint temperature sensor 11 as a basic unit is adjusted to a certain degree of the pipe diameter. By preparing a plurality of types, it is possible to handle all commercially available pipes with a minimum number of units as a whole. That is, it is not necessary to prepare a dedicated pipe surface multipoint temperature sensor 11 for all commercially available pipes.

  This will be described in detail. First, focusing on the length of the heat-sensitive assembly band 13 corresponding to each pipe diameter in Table 5, from 50A to 100A, 40 mm each time the pipe diameter increases by one. It gets longer. Similarly, the length is increased by 80 mm from 100A to 250A, and by 160 mm from 250A to 300A (except between 300A to 350A).

  Based on this relationship, for example, the reference caliber is set to 50A, 100A, and 250A, and the pipe surface multipoint temperature sensor 11 having the length of the heat-sensitive gathering zone corresponding to each pipe caliber is prepared as a basic unit. deep. Then, for these three types of pipe surface multipoint temperature sensors 11 serving as basic units, the minimum number of extension units 21 used to extend the heat-sensitive aggregate zone by “40 mm”, “80 mm”, and “160 mm”, respectively. If prepared, it can be applied to all pipes listed in Table 5. Incidentally, the extension unit 21 shown in FIG. 8 is a type that extends the heat-sensitive gathering zone by 40 mm (type that increases the two heat-sensitive parts: the number of pole parts is three), and the 80 mm extension type increases the heat-sensitive part by four. The type (the number of poles is 5) and the 160 mm mm extension type are the types (the number of poles is 9) that increases the number of heat sensitive parts by eight. Table 6 shows a list of combinations.

  According to this, it can be seen that if three types extending 40 mm, five types extending 80 mm, and four types extending 160 mm are prepared, all pipes having a pipe diameter of 50 A to 500 A can be handled.

  When measurement is performed using the extension unit 21 as described above, for example, a thread marked for each pole length (20 mm) is prepared in advance, and the thread is wound around the pipe on which the sensor is to be installed. After that, by arranging the sensor on the pipe according to the mark attached to the thread, even if a plurality of extension units are connected in series, they can be installed on the pipe surface without bending.

  The example shown in Table 6 is an example, and the pipe surface multipoint temperature sensor 11 serving as a basic unit is more effective in actual use if it is set to a pipe diameter that is frequently used. Further, as described above, by dividing the pipe surface multipoint temperature sensor 11 serving as the basic unit and the extension unit, the utilization factor of the sensor can be improved, and if a problem such as disconnection occurs in any of the sensors, the problem is Replacing only the sensor that occurs can be handled quickly and is economically advantageous.

  Further, for example, the following can be proposed as a method for further simplifying the mounting of the pipe surface multipoint temperature sensor according to the present invention and reducing troubles such as sensor disconnection.

  For example, like a support fitting used for supporting a pipe, the inner surface of the fitting is equal to the curvature of the outer surface of the pipe, and one end can be tightened with a screw or the like (for example, divided into two in a semi-annular shape) If the pipe surface multipoint temperature sensor according to the present invention is attached to the inside of the metal fitting (the side in contact with the pipe), the sensor is attached to the pipe using the above metal fitting. You can complete this by installing on. Therefore, the sensor can be attached very simply and quickly, and the same attachment state can be realized no matter who performs the attachment work.

  In this case, if a cushioning material is placed between the metal fitting and the pipe surface multipoint temperature sensor according to the present invention, the elasticity of the cushioning material is more reliable and uniform when the metal fitting screw is tightened. The sensor can be brought into close contact with the pipe. Further, the heat insulating property of the cushion material makes it difficult to be influenced by the ambient temperature.

  About the sensor side which contacts piping, it is good to stick a member (for example, copper foil tape etc.) with high heat conductivity on the surface of a sensor, etc., and to reinforce a heat-sensitive collective zone. By doing so, it is possible to prevent disconnection in the heat-sensitive collective zone without impairing the responsiveness of the sensor itself. In such a case, it is necessary to paste an insulating tape between the copper foil tape and the heat-sensitive assembly band.

  The present invention is useful for measuring the surface temperature of a pipe through which a fluid flows, and is particularly effective in determining the flow velocity of the fluid from changes in the pipe surface temperature.

1a to 1e Thermocouple 2 + Leg 3 -Leg 4 Thermosensitive part 11 Piping surface multipoint temperature sensor 12 Thermosensitive part 13 Thermally sensitive band 14, 17, 22, 23 Wire 15 Measuring device 16, 18 Wiring connection terminal 21 Extension unit 24 , 25 Wiring connection terminal 26, 27 Heat sensitive part P, p Anode part N, n Cathode part

Claims (4)

A temperature sensor that is attached to the pipe surface and measures the temperature of the pipe surface,
The thermocouple element is made of a conductive material having a property of being a + leg, and an anode portion having a certain length and a cathode portion having a certain length being made of a conductive material having a property of being a-leg are joined alternately. As a whole, even-numbered pole portions are joined in series so that the other end is a cathode portion,
The anode part and the cathode part are in the form of a thin plate exposed so as to be in close contact with the pipe surface ,
A heat-sensitive part is constituted by a joint part of the anode part and the cathode part, and a connection body of the anode part and the cathode part forms a belt-like heat-sensitive aggregate band,
A pipe surface multipoint temperature sensor characterized in that an anode part and a cathode part located at both ends are respectively connected to a wire connecting terminal connected to a measuring instrument. The pipe surface multipoint temperature sensor according to claim 1, wherein the fixed length is 20 mm. A temperature sensor that is attached to the pipe surface and measures the temperature of the pipe surface,
The thermocouple element is made of a conductive material having a property of being a + leg, and an anode portion having a certain length and a cathode portion having a certain length being made of a conductive material having a property of being a-leg are joined alternately. As a whole, even-numbered pole portions are joined in series so that the other end is a cathode portion,
To the anode part and the cathode part located at both ends, the wire connected to the wiring connection terminal connected to the measuring device is connected respectively.
The temperature sensor further includes an extension unit,
In the extension unit, the anode part and the cathode part are alternately joined, and an odd number of pole parts as a whole are connected in series,
The pole portion located at one end of the extension unit is provided with a connecting strand connected to the strand,
Wherein the pole portion located at the other end of the extension unit, characterized in that the wires to be connected to the wiring connection terminals are provided, the pipe surface multipoint temperature sensor. The pipe surface multipoint temperature sensor according to any one of claims 1 and 2, wherein the pipe surface multipoint temperature sensor is previously attached to the peripheral surface of the pipe in an annular shape in a direction perpendicular to the axis of the pipe. tube.

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