JPH01155224A - Temperature sensor - Google Patents

Abstract

PURPOSE:To detect accurate temp., by providing an optical detector for detecting the displacement of a movable part varying by the change in the transmitted magnetic flux of a temp.- sensitive magnetic body constituting a magnetic circuit along with a magnet. CONSTITUTION:The change curves of the attraction force F between a magnet 2 and a temp.- sensitive magnetic body 1 to temp. at times when the magnet 2 is present at the position of a solid line (a) (a state wherein the magnet 2 is attracted to the temp.-sensitive magnetic body 1) and a two-dot broken line (a state wherein the magnet is attracted to a magnetic body 3) are F1a, F1b and the curves showing the changes of the attraction force F2 between the magnet 2 and the magnetic body 3 to temp. at times when the magnet 2 is present at the positions of the solid line (a) and two-dot broken line (b) are F2a, F2b. Now, when the magnet 2 is present at the solid line position and T1 corresponding to the intersecting point C of the temp. curves F1a, F2a is exceeded, the attraction force F2 between the magnet 2 and the magnetic body 3 becomes larger than attraction force F1 and, therefore, the magnet 2 is attracted to the magnetic body 3 as shown by the two-dot broken line (b). When temp. is lowered in the b-state to become lower than T2 corresponding to an intersecting point D, the magnet 2 is attracted to the temp.-sensitive magnetic body 1 and no current does not flow to the magnet 2 and the disturbance of a magnetic field is not generated.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a temperature sensor using a temperature-sensitive magnetic material.

(Prior art) Temperature-sensitive magnetic materials have the property that their saturation magnetic flux density drops rapidly when the temperature exceeds the Curie temperature. Conventional temperature sensors that utilize this property are as shown in Figure 13. A magnet 31 and a temperature-sensitive magnetic body 32 are provided on the outer periphery of the reed switch 30, and at a temperature lower than the Curie temperature of the temperature-sensitive magnetic body, the magnetic flux generated by the magnet 31 acts as a magnetic body'. Since it passes through the body 32 and contact pieces 33 and 34 made of magnetic material, the contact piece 33 comes into contact with the other contact piece 34 as shown by the solid line, creating a state between the contacts, while the temperature rises above the Curie temperature. Then, temperature-sensitive magnetic material 3
Since the magnetic flux passing through contact piece 33. Due to the elasticity of s4, these are separated and placed between the contact points as shown by the two-dot chain line.

(Problems to be Solved by the Invention) In a temperature sensor using such a conventional temperature-sensitive magnetic material, the magnet 31, There was a problem in that the magnetic field of the magnetic circuit composed of the temperature-sensitive magnetic body 32 and the contact pieces 33 and 34 was disturbed, causing chattering.

In addition, if the temperature detection part and the control equipment that receives the signal are far apart, such as in a water temperature adjustment device for an automobile radiator or a temperature adjustment device used in an automated factory, the temperature detection part is connected to the reed switch 30. Since the detection signal is transmitted to the control equipment etc. via the lead wire, there is a problem in that the lead wire picks up noise, which may cause the control equipment to malfunction.

Furthermore, in the case of the temperature sensor to be attached to the radiator, as shown in FIG. Since the reed switch 3o has to be installed at right angles to the surface of the reed switch 3o, the part housing the temperature-sensitive magnetic material 32 is separated from the water 39 in the container 37, which is the object of temperature detection, which deteriorates detection accuracy. There was a problem.

Also, since the reed switch 30 is used.

There was also a problem in that the positioning of the contact pieces 33 and 34 for contact and separation was delicate and difficult to manufacture.

(Means for Solving the Problems) In order to solve the above problems, the present invention includes: a magnet; a temperature-sensitive magnetic body that constitutes a magnetic circuit together with the magnet; The present invention is characterized in that the temperature sensor is configured with an optical detection device that detects the displacement of the movable part that changes due to changes in the magnetic flux transmitted through the body.

(Example) Fig. 1 is a configuration diagram showing an example of a temperature sensor according to the present invention, where l is a temperature-sensitive magnetic material, which is made of temperature-sensitive ferrite, magnetic shunt steel, amorphous magnetic material, etc., and has a composition of Depending on the change, the Curie temperature can be arbitrarily selected from room temperature to several hundred degrees. 2 is a magnet made of magnetized ferrite or metal as shown by N and S, and 3 is a ferromagnetic material such as iron or permalloy, which has a higher Curie temperature than the temperature-sensitive magnetic material 1. The magnetic body 3 and the temperature-sensitive magnetic body 1 are configured such that their relative distance is a predetermined distance by, for example, storing and fixing them in a cylinder 5, and the magnet 2 is a temperature-sensitive magnetic body. A spacer 6 made of a non-magnetic material fixed to the magnetic material 3 and a spacer 6 made of a non-magnetic material fixed to the magnet 2 so as to move vertically in the drawing depending on the magnitude of the magnetic attraction force to the magnetic material 3 and stick to either of them. A distance shown as H is formed between the reflecting plate 7 (which may alternatively be formed as a reflecting film by vapor deposition, plating, etc., or may be bonded with foil).

8 is an optical detection device including the reflection plate 7.

A light emitting element 9 such as a light emitting diode or a lamp, an optical fiber lO whose tip is fixed through the magnetic body 3 so as to irradiate light from the light emitting element 9 toward the reflective plate 7, and a light emitting element 9 from the reflective plate 7. an optical fiber 11 whose tip is fixed through the magnetic body 3 so as to guide light to the outside;
The light receiving element 12 receives the light derived from the light receiving element 12, and the electrical signal converted by the light receiving element 12 is amplified and compared with a reference value. and a detection circuit 13 that determines whether or not the temperature has reached a predetermined temperature or higher.

The operation of this temperature sensor will be explained with reference to FIGS. 2 and 3. Figure 2 is a diagram showing the relationship between temperature and suction force.
For Fla and Flb, the magnet 2 is connected to the solid line a in Fig. 1.
Magnet 2 and temperature-sensitive magnetic body at the temperature when they are in the position of the two-dot chain line b (the state in which the C8 stone 2 is attracted to the temperature-sensitive magnetic body 1) and the position shown by the two-dot chain line b (the state in which the magnet 2 is attracted to the magnetic body 3) 1, and F2a and F2b are curves showing the changes in the attractive force F1 between the magnet 2 and the magnetic body 3 with respect to the temperature when the magnet 2 is at the positions indicated by the solid line a and the dashed-dotted line in Fig. 1, respectively. It is a curve showing the change in the attraction force F2 during the period. Now, when the 1m stone 2 is at the position shown by the solid line a in Figure 1, the temperature is equal to the curves Fla and F2.
Beyond the TI corresponding to the intersection C with a, the attractive force F2 between the magnet 2 and the magnetic body 3 is larger than the attractive force Fl between the magnet 2 and the temperature-sensitive magnetic body 1 (F2> Fl), so
As shown by the two-dot chain line in FIG. 1, the magnet 2 is attracted to the magnetic body 3. On the other hand, in the above state, when the temperature decreases and becomes lower than T2 corresponding to the intersection of the curves Fib and F2b, the attractive force F1 between the magnet 2 and the temperature-sensitive magnetic body 1 increases. (F2<
Fl).

As shown by the solid line a in FIG. 1, the magnet 2 is attracted to the temperature-sensitive magnetic body l.

As shown in FIG. 3, when the magnet 2 is at the position indicated by the solid line a, the amount of light irradiated from the optical fiber IO, reflected by the reflector 7, and entered into the optical fiber LL is
Since the amount of reflected light is smaller than the amount of reflected light at a nearby position as shown by the dotted chain line, the detection circuit 13 can detect the position of the magnet 2 from the change in the electrical signal caused by the change in the amount of light. In addition, in FIG. 2, if the detected temperature is in the range of 72 to T1, the state a where the magnet 2 is attracted to the temperature-sensitive magnetic body 1 and the state b where the magnet 2 is attracted to the magnetic body 3 are taken. The temperature range is within the gap H shown in Figure 1.
This makes the curves Fla and Fib in Figure 2
It can be adjusted by changing the distance between. Further, the attraction force F2 between the magnet 2 and the magnetic body 3 can be adjusted by adjusting the gap, the material of the magnetic body 3, and the magnetic properties.

Further, as for the processing of the reflected light corresponding to the positions a and b, as shown in FIG. 11, and in state b where the m stone 2 is attracted to the magnetic body 3, the tip of the optical fiber IO is close to the reflection plate 7, so that the reflected light does not enter the optical fiber 11 on the receiving side. It is also possible to configure Further, instead of the magnetic body 3, a magnet that is magnetized so as to be mutually attracted to the magnet 2 can be used.

In this way, by adopting a configuration in which no current flows through the movable part (magnet 2), the disturbance of the magnetic field due to current does not occur as in conventional reed switches, and the optical fiber 10. By using the signal line for transmission of
Since the operating point in the figure shifts from the 0 point to the curve Fib, the attractive force between the magnet 2 and the magnetic body 3 increases, and on the contrary, the attractive force between the magnet 2 and the temperature-sensitive magnetic body 1 decreases.

Furthermore, when the operating point shifts from point D to point E due to a decrease in temperature, the attractive force between the magnet 2 and the temperature-sensitive magnetic material l increases, and the magnet 2
Since the attractive force between the magnetic body 3 and the magnetic body 3 is reduced, stable operation is possible without causing chattering. Furthermore, since there is no metal fatigue part that accompanies use, detection accuracy can be maintained over a long period of time.

55th! U is another embodiment of the present invention, in which a cylindrical guide 14 is attached to the center of the disc-shaped temperature-sensitive magnetic body 1, and a guide hole 2a is provided in the guide 14 at the center of the disc-shaped magnet 2. A ferromagnetic material such as iron or permalloy is used as the cylinder 5A, in which the temperature-sensitive magnetic material 1 and the disc-shaped magnetic material 3 are attached inside, and the outer circumferential surface of the magnet 2 and the cylinder 5A are fitted in a slidable manner. It is configured such that a gap g is always formed between it and the inner circumferential surface. According to this configuration, the temperature-sensitive magnetic body l of the magnet 2 or A large attractive force to the magnetic body 3 can be obtained, reliable operating characteristics can be obtained, and miniaturization can be achieved.

Further, in this embodiment, the optical fiber 10 of the reflection plate 7
．． By forming the surface facing 11 into a concave shape, a light condensing effect can be obtained.

In FIG. 6, the guide 14 is provided in the center of the magnet 2, and the guide 14 is slidably fitted into the guide hole 1a provided in the center of the temperature-sensitive magnetic material 1, and has an equivalent function to that in FIG. I can demonstrate it. In addition, in this embodiment, the light emitting element 15 and the light receiving element 16 are connected to a reflecting plate 7 (the reflecting plate 7 has a surface 7b on which light is irradiated having a concave conical shape to achieve the same light condensing effect as described above). The resin, etc. is attached to the magnetic body 3 through the body 19 so as to face the magnetic body 3.

Lead wires 17 and 18 are connected to each element 15 and 16, and the temperature measurement site, that is, the temperature sensor installation site and the control equipment installation site are close to each other, and there is a risk that the lead wires 17 and 18 may pick up noise. It is suitable for use when there is no such thing.

In the above embodiments, the change in the amount of reflected light received due to the displacement of the reflector plate 7 is detected. However, as shown in FIG. A light-emitting optical fiber lO is attached to the cylinder 5A so that the tip surfaces thereof face each other in the gap between the magnet 2 and the magnetic body 3.
and the light-receiving side optical fiber 11 are attached, and as shown by the solid line a, when the magnet 2 is attracted to the temperature-sensitive magnetic material l, the light irradiated from the optical fiber 10 enters the optical fiber 11, forming a two-point chain. ! As shown in FIG. 1llb, when the magnet 2 is attracted to the magnetic body 3, the light emitted from the optical fiber 19 may be blocked by the magnet 2 and not enter the optical fiber 11. The light-emitting side optical fiber IOA and the light-receiving side optical fiber are attached to the cylindrical body 5A so that when the magnet 2 and the temperature-sensitive magnetic body 2 are attracted to the magnetic body 3, their tip surfaces face each other in the gap between the magnet 2 and the temperature-sensitive magnetic body 3. IIA may also be attached. In this case, optical fibers IOA, IIA
The guide 14 is not interposed in the optical path between the two.

FIG. 8 shows a guide hole 3a in which a cylindrical block 14A, which is integral with the magnet 2 and also serves as a guide, is provided at the center of the magnetic body 3.
A light-emitting element 15 and a light-receiving element 16 are arranged so as to be slidably penetrated and protruded to the outside, and to face each other to the outside.
Corresponding to the shapes ma and b of the magnet 2, the block 14A is a solid line C
When the light emitting element 15 is in the position, the light from the light emitting element 15 reaches the light receiving element 1
6, and when the block 14A is at the position of 2 fish ID, it is blocked by the block 14A. With such a structure, the locations where the light emitting element 15 and the light receiving element 16 (or the optical fibers 10 and 11 provided in place of these) are installed are not restricted by the above-mentioned spacing H, and the installation of these elements, etc. The degree of freedom increases and design and production become easier.

FIG. 9 is a modification of FIG. 8, in which the presence or absence of light entering the light-receiving element 16 is determined by the displacement of the reflection plate 7 provided on the block 14A, rather than whether or not the light is blocked. That is, when the block 14A is at the solid line position C, the light emitted from the light emitting element 15 (which may be an optical fiber 10) is reflected by the reflecting plate 7 and enters the light receiving element 16 (which may be an optical fiber 11), When 14A is at the position indicated by the two-dot chain line d, reflected light is prevented from entering the light receiving element 16.

Fig. 1O shows an embodiment using a coil spring 20, in which a disk-shaped magnetic body 3A and two semi-cylindrical pieces (even cylindrical ones) are divided in half and magnetized as shown in the figure. Good,) A magnet 2A and a cylindrical temperature-sensitive magnetic body IA are fixed, and a disk-shaped magnetic body 3 is placed on the temperature-sensitive magnetic body IA, and a guide 14 fixed through the center thereof is fixed to the disk-shaped magnetic body IA. It is slidably fitted into the guide hole 3a at the center of the body 3A, and a coil spring 20 is interposed between the temperature-sensitive magnetic body IA and the magnetic body 3.
While the temperature-sensitive magnetic substance IA acts as a magnetic body at a detection temperature lower than the Curie temperature of the temperature-sensitive magnetic substance IA, the magnet 2A
Since the magnetic flux from the temperature-sensitive magnetic body 1Aft is transmitted through the temperature-sensitive magnetic body 1Aft, the magnetic body 3 is attracted by the magnet 2A against the force of the coil spring 20 and is at the position indicated by the solid line e, and at this time, the light emitting element 15
The light from the light receiving element 16 is not blocked by the guide 14.
- When the detected temperature exceeds the Curie temperature of the temperature-sensitive magnetic body IA and the temperature-sensitive magnetic body IA loses its magnetism, the force of the coil spring 20 causes the magnetic body 3 to move against the stopper 5a provided on the cylinder body 5. The light emitting element 15 is pushed out as shown by the two-dot chain line f to a position where it abuts on the light receiving element 16, and the light emitted from the light emitting element 15 to the light receiving element 16 is blocked by the guide 14.

In FIG. 1θ, the same effect can be achieved even if a magnetic body or a spacer is provided in place of the temperature-sensitive magnetic body IA, and a temperature-sensitive magnetic body is provided in place of the magnetic body 3A.

FIG. 11 shows an example in which a plate spring 22 made of a magnetic material is used, and includes a temperature-sensitive magnetic body IB to which one end of the plate spring 22 is fixed, a magnet 2B whose one end is coupled to the temperature-sensitive magnetic body IH, and the magnet. 2B
A plate-shaped magnetic body 3B that is coupled to or fitted with the magnet 2B, and a magnetic plate that is screwed through and penetrates the plate-shaped magnetic body 3B so that the spacing between the opposite sides of the plate spring 22 can be adjusted. It is composed of an adjustment screw 21, a light emitting element 15 (which may be the optical fiber 10 described above), and a light receiving element 16 (which may be the optical fiber 11), which is attached to the leaf spring 22 so as to face the plate spring 22 at an angle. Therefore, at a temperature lower than the Curie temperature of the temperature-sensitive magnetic material IB, the temperature-sensitive magnetic material IB and the magnet 2B
, the magnetic body 3B, the adjusting screw 21, and the leaf spring 22 constitute a magnetic circuit, so that the tip side of the leaf spring 22 is attracted to the adjusting screw 22 and comes into contact as shown by the solid line, and in this state, from one light emitting element 15 to The light irradiated on the leaf spring 22 is reflected by the leaf spring 22 and enters the light receiving element 16, and on the other hand,
When the temperature becomes higher than the Curie temperature of the temperature-sensitive magnetic body IB, the magnetic circuit is cut off at the temperature-sensitive magnetic body IB, so the elasticity of the leaf spring 22 causes the leaf spring to tighten the adjustment screw as shown by the two-dot chain line i. At this time, the direction of the light reflected by the leaf spring 22 is changed so that it does not enter the light receiving element 16.

In the configurations shown in Figures 1O and 11, since the elastic member is used, there is less of a problem of metal fatigue over time as in the case of using a bimetal, and moreover, as in the case of using a reed switch, Since this embodiment does not have a contact piece encapsulation structure, there is a large degree of freedom in design, and in other respects, the same effects as the embodiment shown in FIG. 1 can be achieved.

FIG. 12 shows the temperature detection target (
For example, it is a diagram illustrating that it is possible to position the temperature-sensitive magnetic body 1 in a region close to water 39), and the structure of the present invention is applicable to any of the above-mentioned embodiments. Since the temperature-sensitive magnetic body 1 can be installed at the inner end of the tube 36, the temperature-sensitive magnetic body 1 works at a temperature closer to the actual temperature of the temperature detection target 39, thereby improving detection accuracy.

Although the present invention has been described above using examples, it goes without saying that various changes, improvements, and additions can be made without departing from the gist of the present invention when carrying out the present invention.

(Effects of the Invention) As described above, in the present invention, there is provided a magnet, a temperature-sensitive magnetic body constituting a magnetic circuit together with the magnet, and a change in the transmitted magnetic flux of the temperature-sensitive magnetic body included in the magnetic circuit. The temperature sensor is composed of an optical detection device that detects the displacement of the moving part that changes due to the movement of the moving part.Since the movement of the moving part is detected with light, the magnetic field of the magnetic circuit is not disturbed by the detection. Accurate temperature detection becomes possible.

In addition, if the temperature detection part and the device receiving the detection signal are installed far apart, it is possible to use optical fibers, so there is no need to pick up electromagnetic noise and there is no need to worry about malfunctions due to noise. , operational reliability can be improved, and since optical fibers are lighter than conventional lead wires, the weight of signal lines can be reduced, and weight reduction is desired, such as in automobiles. A temperature sensor suitable for various applications is realized.

Further, since the temperature sensor of the present invention can have a temperature-sensitive magnetic body at the end, the temperature-sensitive magnetic body can be positioned near the temperature detection target, and detection accuracy can be improved. .

In addition, there is no need to enclose the contact piece in a container such as glass, unlike temperature sensors that use conventional REIT switches, making it easy to manufacture. Also, by using a magnet in the movable part, stable operation without chattering can be achieved. temperature sensor can be realized.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing one embodiment of a temperature sensor according to the present invention, and FIG. 2 is a diagram showing changes in the attractive force between a magnet and a temperature-sensitive magnetic material or magnetic material in accordance with a temperature change in the embodiment. , FIGS. 3 and 4 are diagrams illustrating the displacement of the movable part and changes in the amount of light exchanged in this embodiment, and FIGS. 5 to 11 are sectional views showing other embodiments of the present invention, respectively. FIG. 12 is a sectional view showing the mounting state of the embodiment of the present invention, FIG. 13 is a side view showing a conventional temperature sensor, and FIG. 14 is a sectional view showing the mounting state of the conventional temperature sensor.

Claims (1)

[Claims] 1. A magnet, a temperature-sensitive magnetic body constituting a magnetic circuit together with the magnet, and a movable part that is included in the magnetic circuit and changes due to a change in the magnetic flux transmitted through the temperature-sensitive magnetic body. A temperature sensor comprising: an optical detection device for detecting temperature; 2. The temperature sensor according to claim 1, wherein the signal transmission path of the optical detection device is an optical fiber. 3. The temperature sensor according to claim 1 or 2, wherein the movable part is the magnet. 4. The third aspect of the present invention is characterized in that the magnet is housed in a cylindrical body and is movably attached while being guided by a guide located at the center of the cylindrical body, and the cylindrical body is made of a magnetic material. Temperature sensor as described in section.