JPS61246638A - Noncontact temperature monitoring method - Google Patents

Abstract

PURPOSE:To obtain a noncontact type temperature monitoring system dispensing with leads or the like, by applying an alternating magnetic field to a sensor comparing magnetic bodies with the known Curie temperature having a fine gap arranged at a measuring section from the circumference to detect changes in the oscillation thereof caused. CONSTITUTION:An induction heating coil 2 is arranged on the circumference of a conductive body 1 to be heated and a high frequency current is fed to the coil 2 from a power source 3 to cause an induction heating of the body 1 being heated, the temperature of which is monitored with a sensor 4 arranged at a measuring section. The sensor 4 is provided with a cylindrical magnetic body 4a having the Curie temperature in the temperature range somewhat higher than a desired heating temperature with two fine gaps G in such a manner as to be housed in a non-magnetic case 4b. A high frequency current flows to the coil 2 to raise the temperature of the body 1 being heated while an alternating magnetic field is applied to the sensor 4 to cause a force between the two magnetic bodies 4a so that they vibrate at the frequency doubling the alternating magnetic field to generate a sound wave, which is detected with a sound wave detector 5. When the temperature of the measuring section is below the Curie temperature, a tense sound wave is generated and as it reaches the Curie temperature, the sound wave becomes weak. This facilitates the judgment of a specified temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention is a non-contact temperature monitoring method that utilizes the fact that a magnetic material discontinuously changes its magnetic properties at the Curie temperature. [Technical background of the invention and its problems] Conventionally, when forming a cable connection part such as a CV cable, an insulating polyethylene tape is twisted in a spindle shape on the conductor connection part, and a heat-resistant tape is wrapped around the outer circumference of the tape. Thereafter, the conductor is heated by induction by passing a high-frequency current through the It heat-conducting heating coil to heat-seal the insulating polyethylene tape. In this method, the conductor is usually heated to about 130 to 150°C, but it is necessary to monitor the conductor temperature to prevent overheating of the conductor due to induction heating. Various methods have been known for such temperature monitoring, such as using a temperature sensor such as a thermal lightning pair.
In either case, it is necessary to directly connect the temperature sensor and the detection section with a lead wire or the like, so they cannot be applied in cases where lead wires cannot be used, such as in the case of induction heating. [Object of the Invention] The present invention has been made in order to eliminate such conventional inconveniences, and there is no need to directly connect the sensor placed in the measurement unit and the detection unit with a lead wire etc. as in the conventional method. The present invention aims to provide a so-called non-contact temperature monitoring method. [Summary of the Invention] That is, the non-contact temperature monitoring method of the present invention includes a sensor consisting of two magnetic materials with a known Curie temperature surrounded by a non-magnetic material with a small gap, arranged in a measuring section, By applying a magnetic field to cause the sensor to oscillate, the temperature of the measuring section can be viewed in a non-contact FM manner. [Embodiments of the Invention] Examples of the present invention will be described below with reference to the drawings. In the embodiment shown in FIG. 1, an induction heating coil 2 is arranged around the outer periphery of a conductive object to be heated 1, and a high-frequency current is passed through the induction heating coil 2 to inductively heat the object to be heated. This is an example of monitoring the temperature. Reference numeral 3 indicates a high frequency power source. In the present invention, prior to the start of induction heating, the object to be heated 1
The sensor 4 is placed in the upper measurement part, and the heated object 1 is placed in the vicinity of the sensor 4.
A sound wave detector 5 such as a microphone is arranged at a position away from the sound source. This sensor 4, for example, as shown in FIG.
Curie temperature 7 in a temperature range slightly higher than the desired heating temperature
c, two cylindrical magnetic bodies 4a with a diameter of 3 to 5n and a length of 5 to Ion, and a minute gap G of about 0.5 to 1n.
is provided and housed in a non-magnetic case 4b. However, in this embodiment, a high-frequency current is then applied to the induction heating coil 2, and with this energization, the heated object 1 is inductively heated and its temperature rises, and at the same time, an alternating magnetic field is applied to the sensor 4. It turns out. Here, in the sensor 4 configured as described above, the magnetic body 4
A force F expressed by the following formula acts between a and 4a, and the alternation 111
It vibrates with the same wave number twice that of 1 and generates a sound wave corresponding to the force F. F-CB' (1/μo 71/μ)/2B: Magnetic flux density in magnetic material μ0: Vacuum permeability μ: Magnetic material permeability At high temperature μ÷μo1 and low rIAr
Since μ〉〉μ0 at tl, the force F is equal to the Curie temperature T
It suddenly changes after C. That is, when 81 degrees of the measurement part is lower than the Curie temperature Tc, the magnetic bodies 4a, 4a
A large force F acts on ffi and generates a strong sound wave, Tc
When it reaches , the force F suddenly decreases and the generated sound waves become extremely weak. By monitoring the sound waves emitted from the sensor 4 during the induction heating using the sound wave detection@5, it is possible to easily determine whether the temperature T of the measuring section is higher or lower than the Curie temperature C1, that is, the desired heating temperature. can be determined. In the above equation, B (magnetic flux density in an 11-mer material) is a temperature below the Curie temperature of the magnetic material, and is homologous to temperature as shown in Figure 3. Therefore, F is also homologous to temperature within that range. Figure. Therefore, if a standard curve of temperature and sound wave intensity is determined in advance, it is possible to change the rIA degree ratio during heating. The above embodiment shows a general example in which the present invention is applied to temperature monitoring of induction heating, but specifically, for example, monitoring of conductor temperature accompanying induction heating when forming a cable connection part can be cited. . In this case, the sensor 4 is placed inside the conductor before the sleeve is attached to the conductor connection part of the cable, and the sonic wave detector 5 is placed on the outer periphery of the cable connection part, as shown in FIG. The method of the invention is carried out in the same manner as in the Examples. The method of the present invention is particularly effective in monitoring the temperature of such cable connections. In the present invention, the temperature that can be monitored or measured is limited by the Curie temperature of the magnetic material, but since the Curie 8 degrees of the magnetic material changes depending on its composition, it is possible to create a magnetic material with any Curie temperature. It is. Therefore, by selecting and using a suitable magnetic material according to the application, the present invention can be widely applied. [Effects of the Invention] As explained above, according to the present invention, a sensor that oscillates with an alternating magnetic field depending on the temperature is placed in the measurement section, so that temperature can be measured and monitored in a so-called non-contact manner. can. Therefore, the scope of application is not limited as in the conventional method.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining an embodiment of the present invention, FIG. 2 is a longitudinal cross-sectional view of a sensor 4 used in the embodiment, and FIG. 3 is a graph showing the temperature dependence of saturation magnetic flux density (BS). It is. 1...Heated object 2...Itl heating coil 3...
...High frequency power supply 4...Sensor 4a...Magnetic material 4b...Non-magnetic material case 5...Sound wave detector G・・・・・・・・・Microgap Applicant Showa iWIm Denshin Co., Ltd. Representative Patent Attorney Satoshi Suyama - (1 other person) 1st (!1 1-2nd figure)

Claims (1)

[Claims] (1) A sensor consisting of two magnetic materials with a known Curie temperature surrounded by a non-magnetic material with a small gap is placed in the measurement section, and an alternating magnetic field is applied from the outer periphery to cause the sensor to oscillate. A non-contact temperature monitoring method characterized by detecting the temperature of a measuring part from changes.