JPH0455733A - Sensor having magnetic film - Google Patents

Abstract

PURPOSE:To make it possible to measure torque highly accurately by forming a magnetic film on the surface of a shaft-shaped member comprising a magnetic material, and forming a surface layer comprising a magnetic material and graphite furthermore on the surface of the magnetic film. CONSTITUTION:A nonmagnetic film 1 is formed on the cut-in part of a shaft- shaped member 4 by a spraying method and the like. A magnetic film 2 is formed on the film 1. A surface layer 3 comprising a magnetic material and graphite is further formed on the surface of the film 2. The magnetic fluxes for recording magnetic signals which are generated from a pair of magnetic signal recording heads 6 are cut off with the film 1 and terminated in the film 2. Therefore, the magnetic signals having the sufficiently large signal strength are recorded in the film 2. When torque acts on a sensor 5 wherein the magnetic signal is recorded, the deviation of the phase is generated between the rectangular-pulse-shaped magnetic signals which are recorded with a pair of the heads 6. Then, the heads 6 are removed, and a pair of magnetic-signal reading heads are arranged at the positions. The torque which is applied on the member 4 can be measured by reading the magnetic signal.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a sensor having a magnetic coating, and more specifically, the present invention relates to a sensor having a magnetic coating, and more specifically, the torque applied to a shaft-like member made of a magnetic material, the rotational speed of the shaft-like member, and the rotation speed of the shaft-like member. The present invention relates to a sensor having a magnetic coating that can measure corners and the like with high precision.

Prior Art A method is known in which a magnetic coating is formed on a shaft-shaped member made of a magnetic material and the applied torque is measured using the magnetic properties. For example, Japanese Patent Publication No. 62-6129 proposes a torque sensor equipped with a magnetostrictive film formed by beam-spraying magnetostrictive metal onto the shaft of a rotating body, and a magnetostrictive detection circuit that detects the magnetostriction generated in the magnetostrictive film. ing.

However, in such torque sensors, the magnetostrictive material itself has a large effect on the sensor characteristics;
For example, there have been problems with temperature dependence and changes over time, making it impossible to detect torque with sufficient accuracy.

Further, a magnetic coating is provided on the surface of the shaft-shaped member, and a magnetic signal recording head magnetically records, for example, a rectangular pulse-shaped signal on the magnetic coating, and a magnetic signal reading head reads the recorded signal. Sensors based on torsional negativity are also known, which detect the torque applied to a shaft-like member.

In order to accurately measure torque, rotation angle, rotation speed, etc. in a sensor based on torsional negativity, it is necessary to have a magnetic coating, a recording head for recording magnetic signals, and It is essential to position the recording head and read head so that the clearance with the read head that reads the magnetic signal is small enough, but if you try to place the recording head and read head sufficiently close to the magnetic coating, There is a limit to reducing the clearance between the recording head and read head and the magnetic coating because there is a risk of contact between the magnetic coating and these heads, resulting in damage to the recording head and read head. However, there was a problem in that the measurement accuracy could not be sufficiently improved.

Purpose of the Invention The present invention forms a magnetic coating on a shaft-like member made of a magnetic material, and utilizes the magnetic properties to reduce the torque applied to the shaft-like member.
It is an object of the present invention to provide a sensor having a magnetic coating that can measure the rotation speed, rotation angle, etc. of a shaft-like member with high precision.

Structure and Function of the Invention An object of the present invention is to form a magnetic coating on the surface of a shaft-like member made of a magnetic material, and further to form a surface layer made of the magnetic material and graphite on the surface of the magnetic coating. ,
This is achieved by constructing the sensor with a magnetic coating.

According to the present invention, a surface layer made of a magnetic material and graphite is formed on the surface of the magnetic coating on which magnetic signals are to be recorded, and which can be scraped off by the read head without damaging the read head. The surface layer is
contains magnetic materials and can themselves record magnetic signals, so even when the recording head and the reading head are placed in a position where there is no risk of contact with the magnetic coating on which the magnetic signal is to be recorded, the magnetic It becomes possible to record signals, and therefore obtain a large playback output, and it becomes possible to measure with high precision the torque applied to the shaft-like member, the rotation angle of the shaft-like member, the rotation speed, etc. .

In a preferred embodiment of the present invention, a non-magnetic coating is formed between the magnetic coating and the shaft-like member.

In a preferred embodiment of the present invention, a non-magnetic film is formed between the magnetic film and the shaft-like member made of a magnetic material, so that when a magnetic signal is recorded by the recording head, the magnetic flux is non-magnetic. Since it is blocked by the magnetic coating and terminates within the magnetic coating, the signal strength recorded in the magnetic coating can be sufficiently increased, and therefore the reproduction output detected by the read head during measurement is also sufficiently high. , the torque applied to the shaft member, the rotational speed of the shaft member,
It becomes possible to measure rotation angles, etc. with high precision. Furthermore, since it becomes possible to record magnetic signals with high signal strength within the magnetic coating, there is no need to uniformly and precisely control the thickness of the magnetic coating using methods such as PVD or CVD. Even if a magnetic film is formed by a film formation method that can be carried out in the atmosphere, such as the 3D or METSUKI method, it is possible to measure with sufficiently high precision. Therefore, it is possible to form a magnetic film simply and in a short time. can.

In a further preferred embodiment of the present invention, the nonmagnetic coating is formed so that even its ends are not exposed to the outside.

According to a further preferred embodiment of the present invention, the magnetic coating is formed on the surface of the non-magnetic coating, and the non-magnetic coating is formed so that the ends thereof are not exposed. However, since the non-magnetic coating is exposed to the outside together with the magnetic material, it becomes possible to effectively prevent the non-magnetic coating from being electrochemically corroded.

In another preferred embodiment of the present invention, while rotating the front rudder shaft member, a magnetic coating liquid comprising a magnetic material, a binder, and a solvent is applied to the surface of the nonmagnetic coating formed on the surface of the shaft member. A magnetic film is formed by coating the magnetic film.

According to another preferred embodiment of the present invention, it is possible to obtain a sensor with a magnetic coating having a smooth surface without performing a surface smoothing treatment after forming the magnetic coating.

In yet another preferred embodiment of the present invention, the magnetic coating is formed by a thermal spraying method, and only the surface layer is thermally sprayed with a mixture of magnetic material and fluororesin, and further, while rotating the shaft member, It is formed by heating at a temperature of 400°C to 400°C.

According to yet another preferred embodiment of the present invention, by melting the fluororesin, it becomes possible to obtain a magnetic coating having a smooth surface.

In the present invention, the magnetic materials contained in the surface layer include:
For example, Fe, Co, N1.7-Fe2O, [:r
O,, Fe3O4, barium ferrite, permalloy, etc. can be used, especially N1, Co, r-F
e203 can be preferably used.

In the present invention, examples of magnetic materials forming the magnetic coating include Fe, Co, N1, r-Fe2[]3, C
rO□, Fe5L, barium ferrite, permalloy, etc. can be used, especially CO1γ-Fe20
3 can be preferably used.

In the present invention, the mixing ratio of the magnetic material and graphite forming the surface layer is such that when the recording head and reading head come into contact with the surface layer, the recording head and the reading head are not damaged, and the surface layer is It can be easily determined within a range that satisfies the condition that it also functions as a recording layer for magnetic signals.

In the present invention, in order to increase the bonding force between the magnetic particles and improve the strength of the magnetic coating, it is desirable that all or part of the surfaces of the magnetic material particles be coated with nickel or a nickel alloy. The coating method is not particularly limited, and plating methods, CVD methods, PVD methods, granulation methods, etc. can be used.

In the present invention, as the nonmagnetic material forming the nonmagnetic coating, for example, ^1.1nSCu, Al2O3, etc. can be used, and in particular, from the viewpoint of ease of manufacture, AI can be preferably used.

In the present invention, examples of binders that can be used when forming a magnetic film by applying a magnetic coating liquid consisting of a magnetic material, a binder, and a solvent include polyvinyl alcohol, polyvinyl butyranone, polyethylene glycol, methylcellulose, and hydroxypropyl. Examples include methylcellulose, carboxymethylcellulose, ethylcellulose, wax, acrylic resin, botanical urethane resin, thermosetting resin, and thermoplastic resin.

In the present invention, solvents that can be used when forming a magnetic film by applying a magnetic coating liquid consisting of a magnetic material, a binder, and a solvent include, depending on the type of binder,
Examples include alcohol solvents, ester solvents, ketone solvents, and aromatic solvents.

In the present invention, the method for forming the magnetic coating and non-magnetic coating is as follows:
Although not particularly limited, thermal spraying, plating, spray coating, and the like can be preferably used.

In the present invention, the thickness of the magnetic coating and non-magnetic coating is not particularly limited, but is usually selected to be about 50 to 100 microns.

Embodiments and Examples Hereinafter, embodiments of the present invention will be described based on the accompanying drawings.
Add detailed explanation.

FIG. 1 shows that a non-magnetic coating 1 and a magnetic coating 2 are formed,
Furthermore, FIG. 2 is a partially cutaway schematic cross-sectional view of a sensor 5 according to an embodiment of the present invention, which is composed of a shaft-shaped member 4 on which a surface layer 3 is formed on the surface of a magnetic coating 2. This is a partial enlarged schematic cross-sectional view of one end portion of the coating 2, and FIG. 3 is a drawing showing magnetic signals recorded on the magnetic coating 1 by a pair of magnetic signal recording rads 6.

In FIG. 1, a shaft-shaped member 4 made of a magnetic material such as iron
A non-magnetic coating 1 and a magnetic coating 2 are to be formed on the surface of the
A notch 7 having a depth approximately equal to the sum of the thicknesses of the surface layer 3 is formed, and the nonmagnetic coating 1 is first formed in the notch 7 by thermal spraying or plating. Thereafter, a magnetic coating 2 is formed on the non-magnetic coating 1 in the same manner, and then a magnetic coating 20 is formed in the same manner.
Surface layer 3 made of magnetic material and graphite on the surface
is formed. As shown in FIG. 2, the non-magnetic coating 1
The end portion of the shaft-shaped member 4 is in contact with the inner surface of the notch 7 formed in the shaft-like member 4, and the magnetic coating 2 and the surface layer 3 are formed on the upper surface thereof, and the non-magnetic coating 1 is shaped member 4
, the magnetic coating 2 and the surface layer 3 are formed so as to be shielded from the outside and not exposed to the outside. In FIG. 2, only one end of the surface layer 3, magnetic coating 2, and nonmagnetic coating 1 is shown, but the other end is formed in the same manner. Therefore, since the non-magnetic coating 1 made of a non-magnetic material is in contact with the magnetic coating 2 made of a magnetic material and is not exposed to the outside, the non-magnetic coating 1 is prevented from being electrochemically corroded. be done.

In this way, the magnetic coating 1 of the sensor 5 consists of the shaft-like member 4 on which the non-magnetic coating 1, the magnetic coating 2 and the surface layer 3 are formed.
3, rectangular pulse signals as shown in FIG. 3 are recorded over the entire circumference in the circumferential direction by a pair of magnetic signal recording heads 6. Here, magnetic coating 2
Since a surface layer 3 made of a magnetic material and graphite is formed on the surface of the rad 6, it is possible to
Even if it is placed in a position where there is no risk of it coming into contact with the magnetic coating 2,
A magnetic signal having a sufficiently large signal strength can be recorded, and furthermore, in this embodiment, a non-magnetic coating 1 that does not pass magnetic flux is provided between the magnetic coating 2 and the shaft-like member 4 made of a magnetic material. Because of this, the magnetic flux for recording magnetic signals emitted from the pair of magnetic signal recording heads 6 is blocked by the non-magnetic coating 1 and terminates within the magnetic coating 2. Therefore, it becomes possible to record a magnetic signal with sufficiently high signal strength in the magnetic coating 2.

When torque acts on the sensor 5 on which the magnetic signals have been recorded in this way, a phase shift occurs between the rectangular pulse-shaped magnetic signals recorded by the pair of magnetic signal recording rads 6, as shown in FIG. Therefore, by removing the magnetic signal recording head 6 and placing a pair of magnetic signal reading heads (not shown) in its position to read the magnetic signal shown in FIG. 4, the torque applied to the shaft member 4 can be reduced. can be measured. Here, as described above, a surface layer made of a magnetic material and graphite is formed between the magnetic signal recording head 6 and the magnetic coating 2, and the non-magnetic coating 1 that does not pass magnetic flux is formed between the magnetic coating 2 and the magnetic coating 2. 2 and a shaft member 40 made of a magnetic material, the signal strength of the magnetic signal recorded in the magnetic coating 1 is sufficiently large, and therefore the output signal strength read by the pair of magnetic signal reading heads Since the shaft member 4 is also large enough, it is possible to achieve high precision.
It becomes possible to detect the torque applied to.

Further, by measuring the number of rectangular pulses with a magnetic signal reading head, the rotation angle of the shaft-like member 40 can be further determined by:
Based on the number of rectangular pulses detected within a predetermined time, the shaft-like member 4
It is also possible to measure the rotational speed of the In this case, a single magnetic signal recording head 6 records a rectangular pulse-shaped magnetic signal, and a single magnetic signal reading head records the magnetic signal in the form of a rectangular pulse.
Of course, magnetic signals may also be read.

Hereinafter, in order to make the effects of the present invention even clearer,
Examples are listed.

Example 1 While rotating a shaft made of 345C with a diameter of 30 mm at a rotational speed of 150 rpm, the thermal spray gun was rotated at a speed of 1.5 m/
The particle size is 44 to 1 on the surface of the shaft.
A 100μ thick aluminum film was formed by spraying 0.05μ aluminum using the plasma spraying method under the thermal spraying conditions shown in Table 1, and a 100μ thick aluminum film was further applied to the surface of this aluminum film using the plasma spraying method. A cobalt coating was formed under the thermal spraying conditions shown in Table 2 to obtain sample #1.

Furthermore, a 30μ thick surface layer consisting of 75wt% nickel and 25wt% nickel was formed on the surface of the cobalt coating of sample #1 by plasma spraying under the spraying conditions shown in Table 3. Got #2.

Sample #1 and sample #2 obtained in this way are
While rotating at 600 rpm, a magnetic signal consisting of rectangular pulses with a frequency of 103 Hz is recorded on the magnetic film using a function generator, and then a VTR erase head (3,50
) is placed at a distance of 50μ from the surface of the cobalt film, the magnetic signal is read, amplified 50 times by an amplifier, and further amplified 5 times by a 50-100 Hz low-pass filter. I asked for the output.

As a result, the reproduction output of sample #1 on which the surface layer was not formed was 9V, and the reproduction output of sample #2 on which the surface layer according to the example of the present invention was formed was 12V.
It has been found that the formation of the surface layer significantly improves the reproduction output.

Therefore, according to this embodiment, a magnetic signal with high signal strength can be recorded on the magnetic film by the pair of function generators, and the reproduction output will also be correspondingly large. Since a surface layer consisting of By detecting the phase difference between the rectangular pulse signals, it is possible to measure the torque applied to the shaft with high precision. Also, by detecting the number of rectangular pulses, it is possible to measure the rotation angle of the shaft. , it becomes possible to measure the rotational speed of the shaft with high precision based on the number of rectangular pulses detected within a predetermined time.

The present invention is not limited to the embodiments and examples described above, and various modifications can be made within the scope of the invention described in the claims, and these are also included within the scope of the present invention. Needless to say, it is something that

Effects of the Invention According to the present invention, it is possible to provide a sensor having a magnetic coating that can measure the torque applied to a shaft-like member made of a magnetic material, the rotational speed of the shaft-like member, the rotation angle, etc. with high precision. It becomes possible.

Table 1

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway cross-sectional view of a sensor according to the actual TMM of the present invention, which is composed of a shaft member on which a non-magnetic coating, a magnetic coating and a surface layer are formed, and FIG. FIG. 3 is a partially enlarged schematic cross-sectional view of one end portion of the coating, and FIG. 3 is a drawing showing magnetic signals recorded on the magnetic coating by a pair of magnetic signal recording heads. FIG. 4 is a drawing showing magnetic signals when torque is applied to the shaft-like member. DESCRIPTION OF SYMBOLS 1...Nonmagnetic coating, 2...Magnetic coating, 3...Surface layer, 4...Shaft-shaped member, 5...Sensor, 6...Magnetic signal recording means, 7...Notch Department.

Claims (1)

[Claims] A sensor having a magnetic coating, characterized in that a magnetic coating is formed on the surface of a shaft-like member made of a magnetic material, and a surface layer made of a magnetic material and graphite is further formed on the surface of the magnetic coating.