JP3060603U - Temperature sensor for electronic thermometer - Google Patents

Abstract

(57) [Problem] To improve the response speed and shorten the temperature measurement time even when the temperature sensing portion of a temperature measurement sensor is formed of a material having low thermal conductivity such as stainless steel. SOLUTION: A pear-skin finish N with an infinite number of scratches or irregularities is applied to an outer surface or an inner surface or both surfaces of a distal end portion of a protective tube 5 serving as a temperature sensing portion. As a result, the heat transfer area is increased, so that the heat transfer efficiency is improved, the response speed is increased, and the temperature detection time is shortened.

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 The present invention relates to a temperature measuring sensor for an electronic thermometer, which constitutes a temperature detecting section of the electronic thermometer.

[0002]

[Prior art]

Electronic thermometers control the temperature of frozen and chilled foods in food warehouses, control the oil temperature of fried foods and the oven temperature in microwave ovens in food factories, and measure the bread and cake dough in bakeries. It is used to check the state of fermentation. In particular, in recent years, it has food poisoning by E. coli O ₁₅₇ has been a problem, in the lunch box of manufacturing plants, etc. that are sold in physical facilities and convenience stores control of school meals, measuring the internal temperature of the cooking products such as meat in an electronic thermometer By doing so, he checks the condition of the fire.

In this type of electronic thermometer, as shown in FIG. 5, a temperature measuring sensor 31 for detecting a temperature is attached to a grip 34 of a sensor probe 33 connected to a thermometer main body 32, The temperature detected at 31 is displayed as a segment on the liquid crystal panel 35 of the thermometer main body 32.

The temperature measuring sensor 31 has a temperature-sensitive element 37 built in at a distal end of a protective tube 36 serving as a temperature-sensitive part. The protective tube 36 is formed in a sheath type, and the inner surface of the distal end and the temperature-sensitive element 37. Is filled with a heat-resistant insulating material 38 such as magnesium oxide powder that insulates and supports the temperature-sensitive element 37 and its lead terminal 37a. As the temperature sensing element 37, an arbitrary element such as a temperature measuring resistance element such as a thermistor or a platinum element, or a temperature measuring contact of a thermocouple is used.

[0005]

[Problems to be solved by the invention]

 By the way, when the conventional temperature measuring sensor 31 pierces the tip of the protective tube 36 into a cooked product such as meat and measures the temperature, the temperature of the tip of the protective tube 36 and the insulating substance 38 and the temperature-sensitive element 37 are measured. Since it takes time to reach the thermal equilibrium state, the response speed is slow and the temperature measurement time is long.

That is, it takes time for the heat of the test object to transfer from the protective tube 36 to the temperature sensing element 37 via the insulating substance 38.

The material of the protective tube 36 is generally stainless steel having excellent heat resistance, corrosion resistance, and mechanical strength. Stainless steel belongs to the class having the lowest thermal conductivity among metals, Compared to the thermal conductivity of other metals (unit: kcal / mh ° C), it is aluminum 196, duralumin 141, copper 330, 73 brass 95, silver 360, molybdenum 120, nickel 77, and platinum 267. On the other hand, stainless steel (18-8 stainless steel) is only 14.

Therefore, when stainless steel is used as the material of the protection tube 36, the heat transfer efficiency from the test object to the protection tube 36 and the heat transfer efficiency from the inner surface of the protection tube 36 to the temperature sensing element 37 are poor. The response speed of the temperature sensor 31 becomes slow, which causes a long temperature detection time.

[0009] Therefore, the present invention has a technical problem to increase the response speed and shorten the temperature measurement time even when the temperature sensing part is formed of a material having a relatively low thermal conductivity such as stainless steel. It is an issue.

[0010]

[Means for Solving the Problems]

 In order to solve this problem, the present invention is characterized in that the outer surface or the inner surface or both surfaces of the temperature sensing part is provided with a pear-skin finish having countless scratches or irregularities.

According to the present invention, since the temperature-sensitive portion is subjected to satin finish and has a larger surface area than a smooth surface such as a mirror surface, the heat transfer area is also increased, and the heat dissipation rate and heat dissipation are increased. Absorption rate increases.

However, when the satin finish is applied to the outer surface of the temperature sensing part, the heat transfer efficiency between the temperature sensing object to be measured and the temperature sensing part is improved, and When applied to the inner surface of the unit, the heat transfer efficiency between the temperature-sensitive unit and the temperature-sensitive element disposed on the inner surface side is improved, so that the response speed is increased and the temperature measurement time is reduced.

Further, since the satin finish can be performed extremely simply and at low cost by sand blasting, shot blasting, liquid honing, or the like, the temperature measuring sensor does not become expensive. Furthermore, if the outer surface of the temperature sensing part consisting of a metal protective tube is subjected to a satin finish by sandblasting or the like, the outer surface is strengthened by work hardening, so that even if it pierces a relatively hard sample to be measured, it may deform. It is less likely to break.

[0014] Furthermore, if the outer surface of the temperature sensing part is made so as to have a fine scratch or dent so that it cannot be visually confirmed, and the surface is matte-finished to make the surface matte, the outer surface resists the surface tension of moisture. When the temperature-sensitive part is brought into contact with a sample containing moisture, the moisture adheres and diffuses to the outer surface of the temperature-sensitive part, improving the heat transfer efficiency. In addition, the response speed becomes faster, and the temperature measurement time is shortened.

Further, if the outer surface of the temperature sensing part is a matte surface, the appearance is as if the design processing has been performed, so that there is no danger of a product complaint due to minute scratches or irregularities.

Further, the temperature-sensitive part comprises a protective tube in which a temperature-sensitive element is disposed on the inner surface of the distal end portion, and a heat-resistant insulating material that insulates a lead terminal behind the temperature-sensitive element in the protective tube. If the gap between the temperature-sensitive element and the inner surface of the distal end of the protection tube is filled with a heat-transfer substance having a higher thermal conductivity than the insulating substance, the heat of the temperature-sensing section transfers the heat-transfer substance. As a result, the heat transfer to the temperature sensing element is faster, so that the heat transfer efficiency is improved as compared with the case where the heat-resistant insulating material is filled up to the tip of the protective tube, the response speed is faster, and the temperature measurement time is shorter.

[0017]

[Embodiment of the invention]

 Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. FIG. 1 is an explanatory view showing an example of a temperature measuring sensor for an electronic thermometer according to the present invention, FIG. 2 is a graph showing temperature characteristics, and FIGS. 3 and 4 are explanatory views showing other embodiments.

A temperature measuring sensor 1 for an electronic thermometer shown in FIG. 1 is attached to a grip 4 of a sensor probe 3 connected to a main body 2 of an electronic thermometer T, and is attached to a distal end of a protective tube 5 serving as a temperature sensing part. , A temperature sensing resistor 6 such as a thermistor or a platinum element, or a temperature sensing element 6 such as a temperature measuring junction of a thermocouple.

The protective tube 5 is formed of a stainless steel tube having a diameter of about 0.25 to 20 mm and having a required length, and has a number of scratches or irregularities on its outer surface or inner surface or both surfaces. The attached satin finish N is applied. In this example, the outer surface of the distal end portion of the protection tube 5 is sand-blasted, shot-blasted, or liquid-honed, etc., so that the surface is matted so that the surface is frosted with minute scratches or depressions and projections that cannot be individually confirmed with the naked eye. N is applied, and the surface area is formed large, so that the heat transfer efficiency is high.

The protective tube 5 is formed in a sheath type, and a heat-resistant insulating material 7 such as magnesium oxide powder for electrically insulating the lead terminal 6 a behind the temperature-sensitive element 6 is provided inside the protective tube 5. And a gap formed between the temperature sensing element 6 and the inner surface of the distal end portion of the protective tube 5 is filled with a heat transfer material 8 having a higher thermal conductivity than the insulating material 7.

As the heat transfer material 8, for example, a paste-like material obtained by mixing a ceramic powder or a glass powder with an epoxy-based or silicon-based resin is used. As the filling efficiency increases, so does the thermal conductivity. The heat transfer material 8 may be conductive or insulative, but when a conductive material is used, the heat-sensitive element 6 is insulated as a thermistor in which the element portion is sealed with glass. If a material is used, insulation failure does not occur.

The main body 2 of the electronic thermometer T includes an arithmetic processing unit 9 for obtaining a temperature based on a detection signal of the temperature-sensitive element 6 and a liquid crystal panel 10 for displaying the temperature in a segment.

The above is an example of the configuration of the present invention, and its operation will be described next. For example, when measuring the internal temperature of a cooked product such as meat in order to check the condition of the fire, first, the protective tube 5 is pierced into a cooked product serving as a test object to a predetermined depth.

At this time, since the outer surface of the distal end portion of the protective tube 5 serving as a temperature sensing portion has been subjected to a satin finish N by sand blasting, shot blasting, liquid honing, or the like, the surface is work hardened by mechanical hardening. Target strength is high. Therefore, even when the protective tube 5 is pierced and used not only for the cooked product but also for a relatively hard test object, the protective tube 5 is hardly deformed or broken.

Further, the outer surface of the protective tube 5 is so frosted that the surface thereof is so small that it cannot be individually confirmed by the naked eye, so that the surface of the protective tube 5 is matte. ) Is not only larger, but also has a stronger affinity for the surface tension of water, making it easier to wet. Therefore, when the tip of the protective tube 5 is pierced into the cooked product, the moisture of the cooked product adheres and diffuses to the outer surface of the temperature sensing part, thereby improving the heat transfer efficiency. As a result, the response speed is increased and the temperature measurement time is shortened. You. Moreover, if the outer surface of the protective tube 5 is made to be a matte surface, the appearance will be as if the design processing has been performed, so that there is no danger of product claims due to minute scratches or irregularities.

Next, the heat that has reached the inner surface side of the protective tube 5 is transmitted to the temperature-sensitive element 6 via the heat transfer material 8 filled inside. Since the heat transfer material 8 has a higher heat conductivity than the heat-resistant insulating material 7 such as magnesium oxide powder which has been filled up to the tip of the protection tube 5 in the past, the heat transfer efficiency to the temperature-sensitive element 6 is improved. Is improved. Further, since the amount of the heat transfer material 8 filled in the gap between the inner surface of the distal end portion of the protection tube 5 and the temperature sensing element 6 is extremely small, the use of an expensive material has little effect on the overall price. .

As described above, since the matte finish N is applied to the outer surface of the distal end portion of the protective tube 5, heat is efficiently transmitted from the cooked product to the protective tube 5, and the heat is transferred to the inside of the distal end portion of the protective tube 5. Since the heat substance 8 is filled, the heat is efficiently transmitted from the inner surface of the protective tube 5 to the temperature sensing element 6 via the heat transfer substance 8, and the response time of the temperature measurement sensor 1 is shortened. The temperature can be detected quickly, and the temperature detection time is shortened.

FIGS. 2A and 2B are graphs showing temperature response characteristics when the temperature rises from −11 ° C. to + 17 ° C. and when the temperature falls from + 17 ° C. to −11 ° C., respectively. The measurement was carried out by alternately placing in a stirred water tank. The temperature measuring sensor 1A used in the experiment uses a stainless protective tube 5 having a diameter of 2 mm, a wall thickness of 0.3 mm, and a length of 150 mm. A paste-like heat transfer material 8 in which an epoxy resin and a ceramic powder are mixed is filled in the gap between the heat-sensitive element 6 and the rear side of the temperature sensing element 6 is filled with a magnesium oxide powder serving as an insulating substance 7. The temperature measuring sensor 1B was filled with magnesium oxide powder up to the tip of the protective tube 5, subjected to sand blasting on the outer surface, and otherwise used the same standard as the temperature measuring sensor 1A. Further, a temperature measuring sensor 1C as a comparative example is filled with magnesium oxide powder up to the tip of the protective tube 5, does not perform sandblasting on its outer surface, and uses a sensor of the same standard as the temperature measuring sensor 1A except for the above. Was.

The graphs of FIGS. 2A and 2B show temperature on the vertical axis and time on the horizontal axis. From these, the time required for a 100% response at both the time of temperature rise and temperature fall is measured. It can be seen that the temperature sensor 1A took about 8 seconds, the temperature sensor 1B took about 12 seconds, and the temperature sensor 1C took about 15 seconds. From the comparison between the temperature measurement sensors 1A and 1C, the response time can be reduced by about 50% by performing sandblasting on the outer surface of the distal end portion of the protective tube 5 and filling the inside with the heat transfer material 8. From the comparison between 1B and 1C, it can be seen that the sandblast treatment alone can reduce the time by about 20%.

The temperature measuring sensor for an electronic thermometer of the present invention is not limited to the one used by being connected to the main body 2 of the electronic thermometer T, but may be formed integrally with the main body 2. The protection tube 5 is not limited to metal, but may be a metal coated with Teflon or the like, or may be made of hard vinyl chloride. Further, the protective tube 5 is not limited to the sheath type, but may be a seal pipe type.

In the above description, the case where the satin finish N is applied only to the outer surface of the distal end portion of the protection tube 5 is described. However, the satin finish N is applied only to the inner surface, or both the outer surface and the inner surface are applied. The case where the satin finish N is applied may be used. By applying satin finish N to the inner surface of the protective tube 5, the rate of heat dissipation from the inner surface of the protective tube 5 to the thermosensitive element 6 is increased, and the heat transfer efficiency is improved.

Further, the present invention is not limited to the case where the temperature sensing portion is formed by the protective tube 5. For example, a spherical cap 12 having the temperature sensing element 6 built therein, such as a temperature measurement sensor 11 for measuring surface temperature shown in FIG. The outer surface, the inner surface, or both surfaces thereof may be provided with a satin finish N, and the form is arbitrary.

As shown in FIG. 4, the present invention is applied to a temperature measuring sensor 19 for detecting the temperature of the inner surface 17 b of the distal end portion 17 of the protective tube 16 by an infrared thermosensitive element 18 arranged in the grip 15. By applying, the outer surface 17a or the inner surface 17b of the distal end portion 17 of the protective tube 16 serving as a temperature sensing portion or both surfaces thereof may be subjected to satin finish N.

[0034]

[Effect of the invention]

 As described above, according to the present invention, the outer surface or the inner surface or both surfaces of the temperature sensing part is subjected to a satin finish with countless scratches or irregularities, and compared to a smooth surface such as a mirror surface. Since the heat transfer area (surface area) is large, the heat transfer efficiency of the outer or inner surface or both sides of the temperature sensing part is improved, the response speed of the temperature sensor is faster, and the temperature measurement time can be shortened. It has the effect.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an example of a temperature sensor for an electronic thermometer according to the present invention.

FIG. 2 is a graph showing temperature response characteristics.

FIG. 3 is an explanatory view showing another embodiment.

FIG. 4 is an explanatory view showing another embodiment.

FIG. 5 is an explanatory view showing a conventional device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Temperature measuring sensor for electronic thermometer T ... Electronic thermometer 5 ... Protective tube (temperature sensing part) N ... Satin finish 6 ... Temperature sensing element 7 ... Heat resistant insulating material 8 ... heat transfer material

Claims (4)

[Utility model registration claims] 1. A satin finish (N) having an infinite number of scratches or irregularities on the outer surface or inner surface or both surfaces of the temperature sensing portion (5).
A temperature sensor for an electronic thermometer. 2. The temperature sensor for an electronic thermometer according to claim 1, wherein the satin finish (N) is applied by sand blast, shot blast, or liquid honing. 3. A matte finish (N) on the outer surface of said temperature sensing portion (5) to form a frosted surface by making fine scratches or irregularities so as not to be individually visible to the naked eye. Item 3. A temperature measuring sensor for an electronic thermometer according to Item 1 or 2. 4. The temperature-sensitive part comprises a protective tube (5) having a temperature-sensitive element (6) built-in at a tip end thereof, and the temperature-sensitive element is provided inside the protective tube (5) behind the temperature-sensitive element (6). Side with its lead terminals (6
a) is filled with a heat-resistant insulating material (7) that electrically insulates the insulating material (7), and the insulating material (7) is filled in a gap formed between the temperature-sensitive element (6) and the inner surface of the distal end of the protective tube (5). 4. The temperature measuring sensor for an electronic thermometer according to claim 1, 2 or 3, which is filled with a heat transfer material (8) having a higher thermal conductivity than (3).