Thermal sensor and liquid physical property detection method

Abstract

To provide a thermal sensor capable of detecting physical properties of a liquid with high accuracy even in an environment in which the liquid has a flow.SOLUTION: A thermal sensor including a temperature detection unit 10 that detects a temperature of a liquid in an immersed state in the liquid, and heating means for heating the liquid around the temperature detection unit 10, detects physical properties of the liquid from a relation between a heating aspect of the liquid by the heating means and a change aspect of the temperature detected by the temperature detection unit 10. A inside cover 30 for storing the temperature detection unit 10 and an outside cover 40 covering an outside of the inside cover 30 so as to have a gap between an outer surface of the inside cover 30 and itself are provided in the thermal sensor. A pair of openings α for outflowing / inflowing the liquid inside / outside the inside cover 30 are provided in the inside cover 30. The temperature detection unit 10 is arranged on a line connecting one opening α1 and the other opening α2. A pair of openings β for outflowing / inflowing the liquid inside / outside the outside cover 40 are provided in the outside cover 40 so as not to overlap with the pair of openings α.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a heat-sensitive sensor capable of detecting the physical properties of a liquid from the relationship between the heating mode of the liquid and the change mode of its temperature, and a method for detecting the physical properties of a liquid using this heat-sensitive sensor.

Background Art

[0002] Conventionally, a heat-sensitive sensor that detects the physical properties of a liquid by measuring the temperature change of the liquid while heating it with a heating means is known (see, for example, Patent Documents 1 to 3). With this heat-sensitive sensor, the thermal conductivity and kinematic viscosity of a liquid can be detected.

[0003] That is, by measuring the temperature change of the liquid when heated for a short time by the heating means, the degree of heat dissipation from the heating means into the liquid can be grasped. Since the degree of heat dissipation into the liquid has a high correlation with the thermal conductivity of the liquid, if the degree of heat dissipation into the liquid can be grasped, the thermal conductivity of the liquid can be detected.

[0004] Also, by measuring the temperature change of the liquid when heated for a long time by the heating means, the flow rate of the liquid moving by convection (natural convection) can be grasped. Since the flow rate of the liquid moving by natural convection has a high correlation with the kinematic viscosity of the liquid, if the flow rate can be grasped, the kinematic viscosity of the liquid can be detected.

[0005] The heat-sensitive sensor is used, for example, for applications such as identifying the type of liquid or determining the purity (concentration) of the liquid. Examples of the liquid to be measured include hydrocarbon-based liquids such as gasoline, naphtha, kerosene, light oil, or heavy oil, alcohol-based liquids such as ethanol or methanol, and aqueous urea solution liquids.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

[0007] By the way, when a thermal sensor is immersed in a stationary liquid without flow (for example, when immersed in a liquid stored in a tank), it can detect physical properties such as the thermal conductivity and kinematic viscosity of the liquid with high precision. On the other hand, when immersed in a liquid with flow (for example, when immersed in a liquid flowing in a pipe), there is a problem that the accuracy of such detection decreases.

[0008] That is, even if the liquid is heated by a heating means, if the liquid near the temperature detection part is immediately replaced by new liquid due to the forced flow of the liquid, it is impossible to accurately grasp the heat dissipation condition (thermal conductivity) from the heating means into the liquid. Further, even if the flow velocity of the liquid can be captured, the flow velocity reflects not only the natural convection generated by the heating by the heating means but also the flow of the liquid other than natural convection (the flow of the liquid by forced convection). For this reason, it is impossible to accurately grasp the flow velocity (kinematic viscosity) due to the natural convection of the liquid. In order to detect the thermal conductivity and kinematic viscosity of a liquid with high precision by a thermal sensor, it is necessary for the liquid around the temperature detection part of the thermal sensor to be stationary before heating the liquid (initial state).

[0009] The present invention has been made to solve the above problems, and provides a thermal sensor capable of detecting the physical properties of a liquid with high precision not only in an environment where the liquid has no flow but also in an environment where the liquid has flow. It is also an object of the present invention to provide a method for detecting the physical properties of a liquid using this thermal sensor. [Means for Solving the Problems]

[0010] The above problem is solved by a temperature detection unit that detects the temperature of the liquid while being immersed in the liquid, heating means for heating the liquid around the temperature detection unit, and is provided with a heat-sensitive sensor that detects the physical properties of the liquid from the relationship between the heating mode of the liquid by the heating means and the change mode of the temperature detected by the temperature detection unit, an inner cover for housing the temperature detection unit, an outer cover that covers the outside of the inner cover with a gap existing between the outer surface of the inner cover, and is provided with an opening α for allowing the liquid to flow in and out inside and outside the inner cover is provided in pairs on the inner cover, the temperature detection unit is arranged on a line connecting one opening α and the other opening α, and an opening β for allowing the liquid to flow in and out inside and outside the outer cover is provided on the outer cover in a state where it does not overlap with the pair of openings α characterized heat-sensitive sensor is solved by providing

[0011] In the heat-sensitive sensor of the present invention, in addition to the temperature detection unit being doubly covered by the inner cover and the outer cover, the opening α of the inner cover and the opening β of the outer cover are arranged in a non-overlapping state. For this reason, in the inner cover and the outer cover, while allowing the liquid to flow in and out due to natural convection or pressure difference, the influence of the liquid flow (forced convection) outside the outer cover is less likely to reach the periphery of the temperature detection unit. Therefore, it is possible to detect the physical properties such as the thermal conductivity and kinematic viscosity of the liquid with high accuracy.

[0012] Incidentally, natural convection occurs based on the principle that a liquid with a reduced density due to expansion by heating rises, and a liquid with an increased density due to contraction by cooling descends. Therefore, when natural convection occurs, it is accompanied by the movement of the liquid in the vertical direction. Thus, when detecting the physical properties of a liquid (particularly the kinematic viscosity of the liquid) using the thermal sensor of the present invention, it is preferable to immerse the thermal sensor in the liquid with one opening α and the other opening α overlapping in the vertical direction. This enables smooth natural convection to occur inside the inner cover when the liquid around the temperature detection unit is heated. As a result, it becomes easier to capture the flow velocity of the liquid moving by natural convection.

[0013] In the thermal sensor of the present invention, the opening β is provided in pairs on the outer cover, and both openings β are arranged only in one region (hereinafter sometimes referred to as the "back surface of the outer cover") when the outer cover is bisected in its circumferential direction. No opening β is located in the other region (hereinafter sometimes referred to as the "front surface of the outer cover"). This is preferable.

[0014] Thus, even when there is a flow due to forced convection in the liquid outside the outer cover, it is possible to prevent the liquid from vigorously entering the inside of the outer cover. That is, if the thermal sensor is immersed in the flowing liquid in a state where the other region (front surface) of the outer cover receives the liquid flow, the liquid outside the outer cover hits the front surface of the outer cover and then wraps around to the back side, and then enters the inside of the outer cover through the opening β on the back side. In this situation, the inflow of the liquid into the outer cover through the opening β basically occurs only when a pressure difference is generated between one opening β and the other opening β. The flow velocity of the liquid flowing into the inside of the outer cover due to the pressure difference becomes considerably slower than the flow velocity of the flow due to forced convection. In this way, if the flow velocity of the liquid flowing into the inside of the outer cover can be slowed down, the liquid inside the inner cover (the liquid before the start of heating by the heating means (initial state)) can be made closer to a stationary state.

[0015] In the thermal sensor of the present invention, it is also preferable to accommodate an additional detection unit for detecting the state of the liquid at a location inside the outer cover and outside the inner cover. This is because the liquid gently exchanges inside and outside the inner cover, so the temperature detection unit arranged inside the inner cover cannot quickly detect a change in the properties of the liquid outside the outer cover when the properties of the liquid outside the outer cover change. In this regard, although the liquid gently exchanges inside and outside the outer cover, the time required for the exchange is shorter than that of the inner cover. Therefore, the detection unit (additional detection unit) provided at a location inside the outer cover and outside the inner cover can quickly detect a change in the properties of the liquid outside the outer cover compared to the detection unit (the above temperature detection unit) provided inside the inner cover.

[0016] In this case, as the additional detection unit, one that detects physical properties that are not easily affected by the flow of the liquid (for example, a capacitance sensor that detects the dielectric constant of the liquid, etc.) can be preferably used. Also, one that can detect the presence or absence and degree of the flow of the liquid outside the outer cover can be provided as the additional detection unit. In this regard, when a flow of liquid occurs outside the outer cover, the temperature of the liquid inside the outer cover changes. Therefore, by providing a temperature sensor as the additional detection unit (a temperature sensor different from the temperature detection unit housed inside the inner cover. In the following, it may be referred to as the "additional temperature sensor") and monitoring the change in the temperature of the liquid inside the outer cover with this additional temperature sensor, it becomes possible to grasp the presence or absence and degree of the flow of the liquid outside the outer cover.

Advantages of the Invention

[0017] As described above, according to the present invention, it becomes possible to provide a heat-sensitive sensor that can detect the physical properties of a liquid with high precision not only in an environment where there is no flow of the liquid but also in an environment where there is a flow of the liquid. Also, it becomes possible to provide a method for detecting the physical properties of a liquid by using this heat-sensitive sensor.

Brief Description of the Drawings

[0018]

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BEST MODE FOR CARRYING OUT THE INVENTION

[0019] Embodiments of the thermal sensor of the present invention will be specifically described with reference to the drawings. In the following, two embodiments (the first embodiment and the second embodiment) will be taken as examples to describe the thermal sensor of the present invention. However, these embodiments are merely preferred embodiments, and the technical scope of the thermal sensor of the present invention is not limited to these embodiments. The thermal sensor of the present invention can be appropriately modified within a range that does not impair the gist of the invention.

[0020] 1. Thermal Sensor of the First Embodiment First, the thermal sensor of the first embodiment will be described. FIG. 1 is a partially broken perspective view showing the thermal sensor of the first embodiment. In FIG. 1, an inner cover 30 and an outer cover 40, which will be described later, are shown cut along a plane perpendicular to the x-axis and including the center line L. FIG. 2 is a cross-sectional view showing the thermal sensor of the first embodiment in a state of being cut along a plane perpendicular to the y-axis and passing through the opening β. In FIGS. 1 and 2, for convenience of explanation, a rectangular coordinate system composed of the x-axis, y-axis, and z-axis is shown. The directions of the x-axis, y-axis, and z-axis in FIG. 1 are made to coincide with the directions of the x-axis, y-axis, and z-axis in FIG. 2, respectively. When the thermal sensor is in use, it is assumed that the thermal sensor is installed such that the x-axis direction and the y-axis direction are substantially horizontal, and the z-axis direction is substantially vertical (up and down direction).

[0021] The thermal sensor of the first embodiment is configured to detect the physical properties (such as thermal conductivity and kinematic viscosity) of a liquid when immersed in the liquid. As shown in FIG. 1, this thermal sensor includes a temperature detection unit 10, a substrate unit 20, an inner cover 30, an outer cover 40, and a sealing member 50. As already described, when the thermal sensor is immersed in a flowing liquid, there is a risk that the physical properties such as the thermal conductivity and kinematic viscosity of the liquid cannot be detected with high precision. However, this thermal sensor is provided with an inner cover 30 and an outer cover 40, so that the influence of the external flow on the outer cover 40 hardly reaches the periphery of the temperature detection unit 10, and the physical properties can be detected with high precision.

[0022] Hereinafter, each part constituting the thermal sensor of the first embodiment will be described in order.

[0023] The temperature detection unit 10 is for detecting the temperature of the liquid. Various temperature sensors can be used for the temperature detection unit 10. As the temperature sensor, a resistance thermometer (including a thermistor thermometer) that detects temperature by utilizing the fact that the electrical resistance of a metal or semiconductor changes in proportion to temperature, a thermocouple that detects temperature by connecting two types of metals and generating an electromotive force corresponding to temperature at the contact point, or a bimetal thermometer that detects temperature by bonding two metal plates with different thermal expansion coefficients and depending on the degree of warping of the metal plates (warping caused by the difference in the thermal expansion coefficients of the metal plates) when the temperature changes are exemplified. In the thermal sensor of the first embodiment, a resistance thermometer is used as the temperature detection unit 10.

[0024] The substrate unit 20 is a plate-shaped member for mounting the temperature detection unit 10. A heating means (not shown) for heating the liquid around the temperature detection unit 10 is also mounted on this substrate unit 20. The type of the heating means is not particularly limited. In the thermal sensor of the first embodiment, a resistance element that generates heat when energized and is provided with an insulating coating is used as the heating means.

[0025] The inner cover 30 is for accommodating the temperature detection unit 10 and the substrate unit 20 (the portion of the substrate unit 20 where the heating means is provided) inside it. By this inner cover 30, the surroundings of the temperature detection unit 10 and the substrate unit 20 are covered. In the thermal sensor of the first embodiment, only one detection unit (temperature detection unit 10) is accommodated inside the inner cover 30, but other detection units can also be accommodated inside the inner cover 30 in addition to the temperature detection unit 10.

[0026] The form of the inner cover 30 is not particularly limited. However, if the inner cover 30 has an angular shape (for example, a polygonal cylindrical shape), vortices or the like may occur in the liquid near the surface (outer surface or inner surface) of the inner cover 30, and the flow of the liquid inside the inner cover 30 is likely to be disturbed. This disturbance has an adverse effect on the detection by the temperature detection unit 10. For this reason, the inner cover 30 preferably has a form without corners, such as a cylindrical shape or an elliptical cylindrical shape. Also in the thermal sensor of the first embodiment, the inner cover 30 is cylindrical. One end side in the length direction of the inner cover 30 (the end on the negative side in the y-axis direction) is closed by a wall-like portion, and the other end side in the length direction of the inner cover 30 (the end on the positive side in the y-axis direction) is an open end that is released. However, the open end of the inner cover 30 is blocked by a sealing member 50 different from the inner cover 30.

[0027] A pair of openings α (opening α 1 and opening α 2 ) are provided in this inner cover 30. The openings α 1 , α 2 are for allowing the liquid to flow in and out inside and outside the inner cover 30. The liquid to be measured is introduced near the temperature detection unit 10 through these openings α 1 , α 2 . The locations where the openings α 1 , α 2 are provided are not particularly limited as long as they are different locations in the inner cover 30, but in the thermal sensor of the first embodiment, the openings α 1 , α 2 are provided at opposing locations (locations opposing across the center line L) on the peripheral wall portion (the peripheral wall portion forming a cylindrical shape) of the inner cover 30.is provided.

[0028] Specifically, one opening α 1 is provided in a portion of the peripheral wall of the inner cover 30 facing the lower side in the vertical direction (negative z-axis direction), and the other opening α 2 is provided in a portion of the peripheral wall of the inner cover 30 facing the upper side in the vertical direction (negative z-axis direction). The opening α 1 and the opening α 2 overlap in the vertical direction (z-axis direction). As already described, when natural convection occurs, it involves the movement of the liquid in the vertical direction. By arranging the openings α 1 , α 2 in this way, when the liquid inside the inner cover 30 is heated by the above heating means, natural convection can occur smoothly around the temperature detection unit 10. That is, the liquid heated by the above heating means is smoothly sent out of the inner cover 30 through the upper opening α 2 , and new liquid (liquid before heating) smoothly flows into the inner cover 30 through the lower opening α 1 (see arrow A 3 in FIG. 1).

[0029] The shape of the openings α 1 , α 2 is not particularly limited, but is usually circular, elliptical, etc. The dimensions (area) of the openings α 1 , α 2 vary depending on the dimensions of the inner cover 30, etc. In the thermal sensor of the first embodiment, the length of the inner cover 30 is about 10 mm and the diameter (outer diameter) of the inner cover 30 is also about 10 mm. At this time, the area of the openings α 1 , α 2 is about 3 - 5 mm 2 each.

[0030] The outer cover 40 is for accommodating the inner cover 30 therein. By this outer cover 40, the outside of the inner cover 30 is covered. The outer cover 40 is larger in dimension than the inner cover 30 to some extent. When the inner cover 30 is accommodated in the outer cover 40, a gap γ is formed between the inner surface of the outer cover 40 and the outer surface of the inner cover 30.

[0031] The form of the outer cover 40 is not particularly limited. However, for the same reason as the inner cover 30, the outer cover 40 preferably has a form without corners, such as a cylindrical shape or an elliptical cylindrical shape. Further, in order to form the above-mentioned gap γ evenly, the outer cover 40 preferably has a form following the inner cover 30. In the thermal sensor of the first embodiment, the outer cover 40 is formed as a cylindrical shape that is slightly larger than the inner cover 30. One end side in the length direction of the outer cover 40 (the end portion on the negative side of the y-axis direction) is closed by a wall-like portion, and the other end side in the length direction of the outer cover 40 (the end portion on the positive side of the y-axis direction) is an open end that is released. However, the open end of the outer cover 40 is in a state of being blocked by the above-mentioned sealing member 50.

[0032] A pair of openings β (opening β 1 and opening β 2 ) are provided in this outer cover 40. The openings β 1 , β 2 serve as portions for allowing liquid to flow in and out between the inside and outside of the outer cover 40. The liquid to be measured flows into the outer cover 40 from the outside through these openings β 1 , β 2 , or flows out from the inside of the outer cover 40 to the outside. Usually, when liquid is flowing in from one opening (for example, opening β 1 ), liquid is flowing out from the other opening (for example, opening β 2 ) (refer to arrow A 1 in FIG. 1). Regarding which of the openings β 1 , β 2 liquid flows into, it depends on the pressure of opening β 1 and the pressure of opening β 2This is determined by comparing the pressure in the opening with the pressure in the opening, i.e. liquid flows in through the opening with the higher pressure and liquid flows out through the opening with the lower pressure.

[0033] Opening β 1 ,β 2 The locations where the openings β are provided are not particularly limited as long as they are different locations on the outer cover 40. In the thermal sensor of the first embodiment, the openings β are provided at substantially opposing locations (opposing locations across the center line L) on the peripheral wall portion (cylindrical peripheral wall portion) of the outer cover 40. 1 ,β 2 Specifically, one opening β 1 is provided in a portion of the peripheral wall of the outer cover 40 facing downward in the vertical direction (negative side in the z-axis direction), and the other opening β 2 The opening β is provided in a portion of the peripheral wall of the outer cover 40 facing vertically upward (negative side in the z-axis direction). 1 and aperture β 2 overlap in the vertical direction (z-axis direction).

[0034] However, the opening β 1 ,β 2 For the opening α 1 ,α 2 If the overlapping is up to the opening β 1 ,β 2 The liquid that flows into the inside of the outer cover 40 from the opening α 1 ,α 2 Therefore, the influence of the flow of liquid outside the outer cover 40 (flow of liquid due to forced convection) may easily extend to the inside of the inner cover 30. Therefore, in the thermal sensor of the first embodiment, the opening β 1 ,β 2 The aperture α 1 ,α 2 Specifically, the opening α 1 ,α 2 The opening β is located at a position shifted in the y-axis direction from 1 ,β 2is provided. As a result, the liquid that has flowed into the inside of the outer cover 40 can be made to flow into the inside of the inner cover 30 after weakening its momentum.

[0035] Also, the opening β 1 , β 2 is arranged offset also in the circumferential direction of the outer cover 40 (the circumferential direction around the center line L). That is, with respect to the openings α 1 , α 2 , their centers are arranged to coincide with the lowest point (the lowest position) and the highest point (the highest position) on the circumferential wall portion of the inner cover 30, respectively. In contrast, for the openings β 1 , β 2 , as shown in FIG. 2, their centers are arranged at positions offset from the lowest point P 1 and the highest point P 2 on the circumferential wall portion of the outer cover 40. 1 and the highest point P 2 on the circumferential wall portion of the outer cover 40.

[0036] In addition, the opening β 1 , β 2 is arranged only in one of the regions δ 1 (FIG. 2) when the outer cover 40 is bisected in its circumferential direction (by a plane S (FIG. 2) perpendicular to the x-axis direction and passing through the center line L, and bisecting the outer cover 40 into the region δ 2 (FIG. 2) and the region δ 1 (FIG. 2)). It is not arranged in the other region δ 2 . As a result, as shown in FIG. 2, even when there is a flow (refer to the arrow A 0 in the same figure) due to forced convection in the liquid outside the outer cover 40, if the heat-sensitive sensor is arranged in a direction that can receive the flow on the region δ 2 side of the outer cover 40, the flow can be prevented from directly entering the inside of the outer cover 40. That is, the liquid outside the outer cover 40 hits the region δ 2 of the outer cover 40 and wraps around to the region δ 1 side, and then, after that, the opening β 1 in the region δ 1 , β 2It comes into the inside of the outer cover 40 through []. Therefore, a violent flow is prevented from occurring inside the outer cover 40, and as a result, the liquid inside the inner cover 30 can be brought closer to a stationary state.

[0037] The lowest point P of the outer cover 40 1 and the highest point P 2 The opening β from 1 , β 2 The deviation angle θ (FIG. 2) of [] is not particularly limited. However, if the deviation angle θ is too small, even if the thermal sensor is arranged as described above, there is a possibility that the liquid outside the outer cover 40 may enter the inside of the outer cover 40 while maintaining its momentum. For this reason, the deviation angle θ is preferably 5° or more, and more preferably 10° or more. However, if the deviation angle θ is made too large, the opening β 1 and the opening β 2 come too close to each other, and a flow such as the arrow A in FIG. 2 1 is less likely to occur inside the outer cover 40. For this reason, the deviation angle θ is preferably 30° or less, and more preferably 20° or less. In terms of the arrangement angle φ (FIG. 2) between the opening β 1 and the opening β 2 , the arrangement angle φ is preferably set in the range of 120 to 170°, and more preferably set in the range of 140 to 160°. In the thermal sensor of the first embodiment, the deviation angle θ is set to about 15°, and the arrangement angle φ is about 150°.

[0038] In the thermal sensor of the first embodiment, as shown in FIG. 1, the liquid flowing into the inside of the outer cover 40 from the opening β reaches the opening α through the gap γ 1 (see the arrow A in the same figure 2 ), and flows into the inside of the inner cover 30. Also, the liquid flowing out from the opening α 2 to the outside of the inner cover 30 reaches the opening β through the gap γ 4 (see the arrow A in the same figure

[0039] The thermal sensor of the first embodiment described above can be suitably used for detecting physical properties of a liquid such as thermal conductivity and kinematic viscosity. Physical properties such as thermal conductivity and kinematic viscosity can be detected from the relationship between the heating mode of the liquid by the heating means and the change mode of the temperature detected by the temperature detection unit 10.

[0040] For example, by measuring the temperature change of the liquid when heated by the heating means for a short time, the degree of heat dissipation from the heating means into the liquid can be grasped, and the thermal conductivity can be detected. That is, when the temperature of the liquid rises significantly even with short-time heating, the thermal conductivity of the liquid is low (when the thermal conductivity of the liquid is low, the heat applied is difficult to diffuse into the surrounding liquid, and the temperature of the liquid near the heating location tends to rise). On the contrary, when the temperature of the liquid hardly rises, the thermal conductivity of the liquid is high (when the thermal conductivity of the liquid is high, the heat applied is easily diffused into the surrounding liquid, and the temperature of the liquid near the heating location is difficult to rise). Therefore, if the relationship between the temperature rise of the liquid at a predetermined heating time and the thermal conductivity of the liquid is obtained in advance, the thermal conductivity of the liquid can be obtained from the temperature rise of the liquid.

[0041] Also, by measuring the temperature change of the liquid when heated by the heating means for a long time, the flow rate of the liquid moving by convection (natural convection) can be grasped, and the kinematic viscosity can be detected. That is, when the temperature of the liquid hardly rises even with long-time heating, it means that the liquid inside the inner cover 30 is quickly replaced by natural convection occurring inside the inner cover 30, and the kinematic viscosity of the liquid is small. On the contrary, when the temperature of the liquid rises significantly, the replacement (natural convection) of the liquid inside the inner cover 30 is slow, and the kinematic viscosity of the liquid is large. Therefore, if the relationship between the temperature rise of the liquid at a predetermined heating time and the kinematic viscosity of the liquid is obtained in advance, the kinematic viscosity of the liquid can be obtained from the temperature rise of the liquid.

[0042] In order to detect physical properties such as the thermal conductivity and kinematic viscosity of such a liquid with high precision, it is necessary for the liquid around the temperature detection unit 10 to be stationary before heating the liquid by the heating means (initial state). In this regard, in addition to including the inner cover 30 and the outer cover 40 as described above, the thermal sensor of the first embodiment has the opening α of the inner cover 30 1 ,α 2 and the opening β of the outer cover 40 1 ,β 2 are designed in terms of their arrangement and the like, so that even when immersed in a flowing liquid, the liquid around the temperature detection unit 10 can be made to be in a stationary state or a state close to it in the initial state.

[0043] The use of the thermal sensor of the first embodiment is not particularly limited, but for example, it can be suitably used for applications such as identifying the type of liquid and measuring the purity (concentration) of the liquid. If the type of liquid can be identified or the purity of the liquid can be measured, for example, it is also possible to determine whether fuels (liquids) and lubricating oils used in transportation equipment such as automobiles and industrial machines such as machine tools are within the standards stipulated by laws and regulations. Examples of the liquid to be measured include hydrocarbon-based liquids such as gasoline, naphtha, kerosene, light oil, or heavy oil, alcohol-based liquids such as ethanol or methanol, urea aqueous solution liquids, lubricating oils, and the like.

[0044] 2. Thermal Sensor of the Second Embodiment Subsequently, the thermal sensor of the second embodiment will be described. Regarding the thermal sensor of the second embodiment, the description will be mainly focused on the configuration that is different from the thermal sensor of the first embodiment described above, and the description of the same configuration as the thermal sensor of the first embodiment will be omitted as much as possible. For the configuration not particularly mentioned in the thermal sensor of the second embodiment, a configuration substantially the same as that described in the thermal sensor of the first embodiment can be adopted.

[0045] Figure 3 is a partially cutaway perspective view of the thermal sensor according to the second embodiment. In Figure 3, the inner cover 30 and the outer cover 40 are shown cut along a plane perpendicular to the z-axis and including the center line L. Figure 4 is an exploded perspective view showing the main part of the thermal sensor according to the second embodiment. Figure 5 is a view of the thermal sensor according to the second embodiment as seen from the positive side in the x-axis direction. Figure 6 is a view of the thermal sensor according to the second embodiment as seen from the negative side in the z-axis direction. Figure 7 is a cross-sectional view showing the state where the thermal sensor according to the second embodiment is cut along the Z 1 -Z 1 plane in Figure 5. Figure 8 is a cross-sectional view showing the state where the thermal sensor according to the second embodiment is cut along the Y 1 -Y 1 plane in Figure 5. Figure 9 is a cross-sectional view showing the state where the thermal sensor according to the second embodiment is cut along the X 1 -X 1 plane in Figure 6.

[0046] In Figures 3 to 9, for the sake of convenience of explanation, a rectangular coordinate system composed of the x-axis, y-axis, and z-axis is shown. Also in the thermal sensor according to the second embodiment (Figures 3 to 9), similar to the thermal sensor according to the first embodiment (Figures 1 and 2), it is assumed that the thermal sensor is installed such that the x-axis direction and the y-axis direction are substantially horizontal, and the z-axis direction is substantially vertical (up and down direction). However, for the sake of illustration convenience, in Figure 3, the directions of the x-axis and the z-axis are changed from Figure 1, so please note (in the thermal sensor according to the first embodiment, as shown in Figure 2, in the outer cover 40, the region δ 2 that receives the liquid flow faces the positive side in the x-axis direction, whereas in the thermal sensor according to the second embodiment, as shown in Figure 8, in the outer cover 40, the region δ 2 that receives the liquid flow faces the negative side in the x-axis direction.).

[0047] In the thermal sensor of the first embodiment described above, as shown in FIG. 1, only the temperature detection unit 10 was provided as the detection unit. On the other hand, in the thermal sensor of the second embodiment, as shown in FIGS. 3, 4, 7, and 9, as the detection unit, not only the temperature detection unit 10 but also an additional detection unit 60 is provided. Also in the thermal sensor of the second embodiment, similar to the thermal sensor of the first embodiment, although the temperature detection unit 10 is arranged inside the inner cover 30, the additional detection unit 60 is arranged outside the inner cover 30 and in the region ε (FIG. 7) which is inside the outer cover 40.

[0048] This region ε is connected directly to the outside of the outer cover 40 through the openings β 1 ,β 2 . Therefore, compared with the inside of the inner cover 30 which is not directly connected to the outside of the outer cover 40, it is a location that is easily affected by the flow of the liquid outside the outer cover 40. In other words, the region ε is a location where it is easier to capture changes in the properties of the liquid outside the outer cover 40 compared with the inside of the inner cover 30. By arranging the additional detection unit 60 in this region ε, when the properties of the liquid outside the outer cover 40 change, it becomes possible to quickly detect the change in the properties.

[0049] The type of the additional detection unit 60 is not particularly limited. For example, as the additional detection unit 60, a temperature sensor (a temperature sensor different from the temperature sensor used for the temperature detection unit 10) can be provided. Thereby, it becomes possible to quickly capture a change in the flow rate of the liquid outside the outer cover 40. This is because when the flow rate of the liquid changes outside the outer cover 40, the temperature of the liquid in the region ε changes.

[0050] In addition, as the additional detection unit 60, one that detects physical properties that are not easily affected by the flow of the liquid can also be provided. In the region ε where the additional detection unit 60 is arranged, since the liquid flows more easily than inside the inner cover 30, if a device that measures physical properties that are easily affected by the flow (such as the thermal conductivity and kinematic viscosity of the liquid) is arranged in the region ε, there is a risk that the physical properties cannot be accurately measured. However, if it is a device that detects physical properties that are not easily affected by the flow (for example, the dielectric constant of the liquid), even if it is installed in the region ε, the physical properties can be measured relatively accurately. Examples of the additional detection unit 60 used in this case include a capacitance sensor. The additional detection unit 60 arranged in the region ε is not limited to one, and may be a plurality.

[0051] Thus, in the thermal sensor of the second embodiment, since the additional detection unit 60 is arranged in the region ε outside the inner cover 30, the forms of the substrate unit 20, the inner cover 30, etc. are changed from those of the thermal sensor of the first embodiment. Specifically, as shown in FIGS. 3 and 4, the substrate unit 20 has a shape extending in the y-axis direction, and the temperature detection unit 10 is provided at a location near one end (the end on the positive y-axis direction side) of the substrate unit 20, and the additional detection unit 60 is provided at a location near the other end (the end on the negative y-axis direction side) of the substrate unit 20. In addition, the inner cover 30 is provided with a substrate insertion port 61 for inserting the substrate unit 20, and a semi-cylindrical portion 62 is provided outside the substrate insertion port 61.

Explanation of Signs

[0052] 10 Temperature detection unit 20 Substrate unit 30 Inner cover 40 Outer cover 50 Sealing member 60 Additional detection unit 61 Substrate insertion port 62 Semi-cylindrical portion α Opening α 1 Opening α 2 Opening β Opening β 1 Opening β2 Opening γ gap δ 1 Region δ 2 Region ε region

Claims

1. A temperature detection unit that detects the temperature of the liquid while being immersed in the liquid, heating means for heating the liquid around the temperature detection unit, and comprising: A heat-sensitive sensor that detects the physical properties of the liquid from the relationship between the heating mode of the liquid by the heating means and the change mode of the temperature detected by the temperature detection unit, an inner cover for accommodating the temperature detection unit, an outer cover that covers the outside of the inner cover with a gap existing between the outer surface of the inner cover, and comprising: An opening α for allowing the liquid to flow in and out inside and outside the inner cover is provided in pairs on the inner cover, the temperature detection unit is arranged on a line connecting one opening α and the other opening α, and an opening β for allowing the liquid to flow in and out inside and outside the outer cover is provided on the outer cover in a state where it does not overlap with the pair of openings α. The heat-sensitive sensor is characterized by the above.

2. The opening β is provided in pairs on the outer cover, and both openings β are arranged only in one region when the outer cover is bisected in its circumferential direction, so that no opening β is located in the other region. The heat-sensitive sensor according to Claim 1.

3. The heat-sensitive sensor according to Claim 1, wherein an additional detection unit for detecting the state of the liquid is accommodated at a location inside the outer cover and outside the inner cover.

4. A liquid physical property detection method for detecting the physical properties of a liquid using the heat-sensitive sensor according to any one of Claims 1 to 3, wherein the heat-sensitive sensor is immersed in the liquid in a direction in which one opening α and the other opening α overlap in the vertical direction.

5. A liquid physical property detection method for detecting the physical properties of a liquid using the heat-sensitive sensor according to Claim 2, wherein the heat-sensitive sensor is immersed in the flowing liquid in a state of receiving the flow of the liquid in the other region of the outer cover.

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