JPH0682316A - Non-contact temperature detector - Google Patents

Abstract

PURPOSE:To exactly measure temperature even if the first member and second member relatively move while changing their reference positions. CONSTITUTION:A first magnet 21 and a second magnet 22 are provided on a wheel part 12 and a magnetism sensitive body 30 is set on a member of a car body side 13. An electric circuit part 40 serves to calculate the real shortest distance X1 in accordance with known relation between a previously obtained integral ratio and the relation between the shortest distance on the basis of the integral ratio I1/I2 of electromotive force of each magnet 21, 22 detected at the time when the first magnet 21 and the second magnet 22 are moved in the neighborhood of the magnetism sensitive body 30, and an integral value I1 deg. at the time of the shortest distance X1 at a reference temperature of T0 is calculated on the basis of the relation between the shortest distance and the integral value at a reference temperature of T0. In addition, the temperature T is calculated on the basis of a ratio I1/I1 deg. of the real detected integral value I1 to the integral value I1 deg..

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact temperature detecting device for detecting the temperature of an object which causes a relative motion such as rotation or the ambient temperature around the object without coming into contact with a subject.

[0002]

2. Description of the Related Art When detecting the temperature of an object such as a rotating body, for example, as disclosed in Japanese Patent Laid-Open No. 62-104453,
It has been proposed to detect the temperature of a rotating body in a non-contact manner by utilizing the property that the magnetic flux density generated by a permanent magnet changes according to the temperature. In this conventional example, a permanent magnet is fixed to a rotating body in a heat conductive state, a magnetic body is arranged with a predetermined gap between the permanent magnet and one pole of the permanent magnet, and the other pole of the permanent magnet is arranged. Is fixed to the magnetic body.
Then, a magnetic circuit including these permanent magnets, air gaps and magnetic bodies is formed, the magnetic flux in the air gaps is detected by a Hall element, and the temperature of the rotating body is detected based on the output change.

[0003]

However, in the case where the magnetic flux density generated by the permanent magnet is detected by the Hall element as described above, if the position of the Hall element is moved from the reference position for some reason, the magnetic field of the magnetic field is changed. Since the strength changes, the output of the Hall element changes regardless of the temperature. Therefore, the temperature cannot be detected accurately.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a non-contact temperature detecting device which can detect temperature accurately even if the positional relationship between two members that move relative to each other changes.

[0005]

The device of the present invention developed to achieve the above object is provided with at least one permanent magnet on one of the first member and the second member which move relative to each other and on the other. Two or more magnetic sensors are provided, or one or more permanent magnets are provided on one side and at least one magnetic sensor is provided on the other side. The electric circuit unit connected to the magnetic sensor, based on a known relationship between the output of each magnet and the relative position of the magnet and the magnetic sensor obtained in advance, by the actually detected output, After the relative position between the magnet and the magnetic sensor is determined, the relative position determined based on the relationship between the relative position of the magnet and the magnetic sensor and the output of the magnetic sensor at a reference temperature that is determined in advance. The reference output at the reference temperature at the position is calculated, and the temperature is calculated based on the calculated reference output and the actual output detected by the magnetic sensor.

While the output of the magnetic sensor changes depending on the relative position of the magnet and the magnetic sensor during the relative movement of the first member and the second member, in this specification, the maximum value of the output during the relative motion is simply referred to as the output. The relative position between the magnet and the magnetic sensor when taking this output is simply referred to as the relative position. This output and the relative position are uniquely determined if the trajectory of the relative motion is determined.

[0007]

By the magnetic field of the permanent magnet provided in the first member, an output corresponding to the relative position of the magnet and the magnet provided in the second member is generated in the magnetic sensor.
For example, when two magnets and one magnetic sensor are used, the output I ₁ from one magnet and the output I _{2 from the} other magnet are detected by the magnetic sensor. This output ratio is a value that does not depend on the temperature, and depends only on the relative position between the magnet and the magnetic sensor.

In the present invention, the relationship between the output ratio not affected by temperature and the relative position is previously obtained by actual measurement or the like as described above, so that the output ratio actually detected by the magnetic sensor can be used. To find the relative position.

Since the magnetic flux density generated by the magnet changes depending on the temperature, the output detected by the magnetic sensor changes at a constant rate according to the temperature. In the present invention, the relation between the relative position at the reference temperature and the output of the magnetic sensor is obtained in advance so that the reference output at the reference temperature can be calculated when the relative position is obtained. Then, the temperature is calculated based on the ratio between the actually detected output and the reference output at the reference temperature at the obtained relative position.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The non-contact temperature detecting device 10 shown in FIG. 1 is for detecting the internal temperature of a pneumatic tire, and is an example of a wheel portion 12 and an example of a second member that are examples of a first member that causes relative movement. Is provided on the member 13 on the vehicle body side. The wheel portion 12 includes a wheel 15 and a tire 16, and is a member 13 on the vehicle body side.
On the other hand, it is rotatable about the X-axis and can be displaced to some extent in the X-axis direction.

Inside the tire 16, the first magnet 21 and the second magnet 21
A magnet unit 23 having a magnet 22 is provided. For the first magnet 21 and the second magnet 22, permanent magnets having the same magnetic flux density and having the same shape are used, and the generated magnetic flux density changes at a constant rate according to the temperature change. . These magnets 21 and 22 are fixed to the wheel 15 via heat insulating materials 25 and 26 in a state in which their positions are displaced from each other by δX in the axial direction of the wheel 15 (X-axis direction).

As shown in FIG. 2, the first magnet 21 and the second magnet 22 are provided so as to be displaced in the circumferential direction of the wheel 15 so as not to be influenced by each other's magnetism.
The magnetizing directions of the magnets 21 and 22 are aligned with the axial direction of the wheel 15 (X-axis direction).

A magnetic sensor 30 as a sensing means is provided on the member 13 on the vehicle body side. An example of the magnetic sensor 30 is an electromagnetic coil, but a magnetically sensitive member such as a Hall element may be used. In this embodiment, an electromagnetic coil is used as the magnetic sensor 30, and the central axis of the electromagnetic coil is aligned with the axial direction of the wheel 15. The magnetic sensor 30 is located on the circumference substantially the same as the locus drawn by the first magnet 21 and the second magnet 22 when the wheel 15 rotates.
When the first and second magnets 22 pass near the magnetic sensor 30, an electromotive force due to electromagnetic induction having a size corresponding to the relative position between the magnets 21 and 22 and the magnetic sensor 30 is generated. There is.

In this embodiment, when the wheel 15 rotates, the positions where the distances from the magnets 21 and 22 to the magnetic sensing body 30 are the minimum are relative to the magnets 21 and 22 and the magnetic sensing body 30. The position. Further, in the present embodiment, the distances X ₁ and X ₂ in the X-axis direction at the relative positions of the magnets 21 and 22 and the magnetic sensing body 30 are respectively set to the respective magnets 2.
It is called the shortest distance from the magnetic sensor 30 to the magnetic sensor 30.

As shown in FIG. 1, an electric circuit section 40 is connected to the magnetic sensor 30. The electric circuit section 40 is
A signal processing circuit 4 for processing the output generated in the magnetic sensor 30.
1, A / D conversion circuit 42, controller 43, and display 4
4 and so on.

The CPU 50 of the controller 43, as will be described later, integrates the electromotive forces I ₁ and I of the first magnet 21 and the second magnet 22 detected by the magnetic sensor 30.
_2, and the temperature T of the magnet 21 is calculated after calculating the shortest distance X ₁ from the first magnet 21 to the magnetic sensor 30 at the temperature T at the time of measurement based on the map and the calculation formula obtained in advance. In addition, the temperature is displayed on the display 44 if necessary.

The process of obtaining the temperature T by the electric circuit section 40 will be described below. When the wheel 15 rotates, the first magnet 21 and the second magnet 22 rotate together with the wheel 15, so that the magnets 21 and 22 pass near the magnetic sensor 30. Then, the magnets 21 and 22 are the magnetic sensor 30.
The magnetic field changes with time each time it passes in the vicinity of, causing an induced electromotive force as shown in FIG.

The induced electromotive force depends on the rotational angular velocity of the wheel 15, but the maximum value I of the time integration of the voltage waveform (the maximum value of the time integration by the first magnet 21 is I ₁ , the maximum of the time integration by the second magnet 22 is the maximum). The value I ₂ ) is the relative position between the magnets 21 and 22 and the magnetic sensor 30, that is, the shortest distance X in the X-axis direction.
₁ , X ₂ and the temperature T of the magnets 21, 22 and are independent of the angular velocity of rotation of the wheel 15. In this embodiment, the maximum value I of the time integration of the induced electromotive force is output.

Since the magnetic flux density generated by the magnets 21 and 22 changes at a constant rate depending on the temperature T, the integrated value I also changes depending on the temperature T. That is, the integrated value I at the temperature T
And the shortest distance X is given by the following equation.

I = J (T) f (X) (1) f (X) is a function of the shortest distance X determined by the shape of the permanent magnet and the direction of magnetization and the shape of the electromagnetic coil, and J (T) is the temperature T Is an amount indicating the magnitude of the magnetic force at, and is represented by J (T) = J ₀ {1-k (T−T ₀ )} (2). Here, T ₀ : reference temperature T: temperature at the time of measurement J ₀ : magnitude of magnetic force of the permanent magnet at the reference temperature T ₀ k: rate of change in magnetic force when temperature rises by 1 ° C. Therefore, integration by the first magnet 21 Value I ₁ and second magnet 22
Integral value I ₂ of each of the shortest distances X ₁ and X ₂
When (X ₂ = X ₁ + δX), I ₁ = J (T) f (X ₁ ) (3) I ₂ = J (T) f (X ₁ + δX) ((3) 4) is represented by. When the equation (4) is divided by the equation (3), I ₂ / I ₁ = {J (T) f (X ₁ + δX)} / {J (T) f (X ₁ )} = f (X ₁ + δX) / F (X ₁ ) ... (5)

That is, the integral ratio I ₂ / I ₁ is equal to each magnet 2
It is a value that is independent of the temperature change regardless of the magnetic forces of 1 and 22, and as shown in FIG. 4, the distance X (shortest distance X ₁ )
Depends only on. Further, δX is a predetermined fixed value. Therefore, by previously obtaining the relationship between I ₂ / I ₁ and X ₁ by actual measurement or calculation, I ₂ / I ₁
So that X ₁ can be obtained when is given.

On the other hand, the integrated value I ₁ ° at the reference temperature T ₀
And the shortest distance X ₁ are represented by I ₁ ° = J (T ₀ ) f (X ₁ ). Here, since J (T ₀ ) is represented by J (T ₀ ) = J ₀ {1-k (T ₀ −T ₀ )} from the above equation (2), I ₁ ° = J ₀ { 1-k (T ₀ −T ₀ )} f (X ₁ ) = J ₀ f (X ₁ ) ... (6)

That is, the output I _{1 at the} reference temperature T ₀
°, if the magnetic force J ₀ of the first magnet 21 at the reference temperature T ₀ is determined, a value determined only by the shortest distance X _1, related as shown in FIG. If this relationship is obtained in advance by actual measurement or calculation, the output I ₁ ° (reference output) at T ₀ can be obtained when X ₁ is given.

The integrated value I ₁ of the first magnet 21 detected at the temperature T during measurement depends on the shortest distance X ₁ and the magnetic force J (T) at the temperature T: I ₁ = J (T ) F (X ₁ ) ... (7)

When the above equations (6) and (7) are divided along each other, I ₁ / I ₁ ° = {J (T) f (X ₁ )} / J ₀ f (X ₁ ) = J (T) / J ₀ According to the equation (2), since J (T) = J ₀ {1-k (T-T ₀ )}, I ₁ / I ₁ ° = [J ₀ {1-k (T-T ₀ ) } / J ₀ = 1−k (T−T ₀ ), therefore T = T ₀ + (1−I ₁ / I ₁ °) / k (8) where T ₀ is the reference temperature (known value ), I ₁ is an integral value (output) actually detected by the magnetic sensor 30, I ₁
° is a value calculated from a known relationship when the shortest distance X ₁ is obtained, and k is a rate of change in magnetic force when the temperature rises by 1 ° C. (known constant). Therefore, according to the above equation (8),
The temperature T is obtained. Further, the amount of temperature change from the reference temperature T ₀ is obtained by (T−T ₀ ).

In the above embodiment, for the sake of easy understanding, the shortest distance X ₁ from the first magnet 21 to the magnetic sensing body 30 is used as a reference, but the shortest distance X ₂ from the second magnet 22 is described.
The same result can be obtained by performing the above calculation with reference to. Further, the first member and the second member are not limited to the wheel and the member on the vehicle body side, but may be any pair of members that make relative movement with each other, and may be movements other than rotational movement.

In the above embodiment, two permanent magnets were used to determine the relative position and temperature in the uniaxial direction.
If used individually, it is possible to obtain the relative position in the biaxial directions and the temperature. Furthermore, if four permanent magnets are used, the positional relationship in the three axial directions and the temperature can be obtained.

As another embodiment of the present invention, as shown in FIG. 6, one permanent magnet 21, a first magnetic sensor 30a and a second magnetic sensor 30a which are arranged so as to be displaced from each other in the X-axis direction. The shortest distance X ₁ from the magnet 21 to the one magnetic sensor 30a or the shortest distance from the magnet 21 to the other magnetic sensor 30b is obtained by using the sensing means including the magnetic sensor 30b, through the same process as the above embodiment. It is also possible to obtain the temperature T after obtaining the distance X ₂ . In this case, if three magnetic sensors are used, the relative position and temperature in the biaxial directions can be obtained, and if four magnetic sensors are used, three can be obtained.
It is possible to obtain the relative position in the axial direction and the temperature. Also, a plurality of magnets and a plurality of magnetic sensors may be used in combination.

[0029]

According to the present invention, even if the reference positions of the first member and the second member that move relative to each other change, the temperature can be accurately detected without being affected by this change.

[Brief description of drawings]

FIG. 1 is a diagram showing a cross section of a wheel unit and a block of an electric circuit unit equipped with a non-contact temperature detecting device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a magnet and a magnetic sensor of the temperature detecting device shown in FIG.

FIG. 3 is a diagram showing an output of a magnetic sensor in the temperature detecting device shown in FIG.

FIG. 4 is a diagram showing a relationship between the shortest distance X and an integration ratio (I ₂ / I ₁ ).

FIG. 5 is the shortest distance X at a reference temperature T ₀ and an integrated value I °
FIG.

FIG. 6 is a partial sectional view of a non-contact temperature detecting device according to another embodiment of the present invention.

[Explanation of reference numerals] 10 ... Temperature detecting device, 12 ... First member (wheel portion), 13
... second member (body-side member), 21 ... first magnet, 22 ...
2nd magnet, 23 ... Magnet part, 30 ... Magnetic sensing body, 40 ... Electric circuit part.

Claims (2)

[Claims] 1. A first member and a second member that move relative to each other, a magnet portion provided on the first member and composed of a plurality of permanent magnets including a first magnet and a second magnet, and the second member. A sensing means provided with at least one magnetic sensing body for producing an output of a magnitude corresponding to the relative position with the magnet; an output for each magnet previously obtained; Based on the known relationship with the relative position, the relative position between the magnet and the magnetic sensor is calculated by the actually detected output, and then the relative position between the magnet and the magnetic sensor at the reference temperature obtained in advance is calculated. An electric circuit unit that calculates a reference output at a reference temperature based on the relationship between the relative position and the output of the magnetic sensor, and calculates the temperature based on the calculated reference output and the actually detected output. Equipped with A non-contact temperature detection device characterized by the above. 2. A first member and a second member which move relative to each other, a magnet portion including at least one permanent magnet provided in the first member, and a magnet provided in the second member and the magnet. Sensing means including a plurality of magnetic sensing bodies including a first magnetic sensing body and a second magnetic sensing body that generate an output having a magnitude corresponding to a relative position; an output for each magnet and a magnet that are obtained in advance; Based on the known relationship with the relative position of each magnetic sensor, the relative position between the magnet and the magnetic sensor is calculated from the actually detected output, and then the magnet at the reference temperature determined in advance A reference output at the reference temperature is calculated based on the relationship between the relative position with respect to the magnetic sensor and the output of the magnetic sensor, and the temperature is calculated based on the calculated reference output and the actually detected output. With the electric circuit section Non-contact temperature detecting apparatus characterized by comprising a.