WO1999026072A1

WO1999026072A1 - Speed sensor

Info

Publication number: WO1999026072A1
Application number: PCT/JP1998/005169
Authority: WO
Inventors: Makoto Naruse; Takatomo Hiruma; Kazunari Shibuya
Original assignee: Sumtak Corporation
Priority date: 1997-11-18
Filing date: 1998-11-17
Publication date: 1999-05-27

Abstract

A speed sensor comprising a core (3) as a magnetic body having a U-shaped cross section, sensing coils (4a and 4b) which are wound around the core (3) and convert a change in the magnetic flux density in the core (3) into an electric signal, a magnetoelectric transducing unit (1) having permanent magnets (2a and 2b) at both ends of the core (3) for supplying a magnetic flux to the core (3), and a sensing plate (8) which is a disc-shaped magnetic body which rotates synchronously with an object to be sensed, and has recesses (8b) and projections (8a) formed sequentially in the circumferential direction at the edge face, in which a magnetic path is formed together with the core via the recesses (8b) and the projections (8a). The magnetoelectric transducing unit is so disposed that the end of the core faces the edge face of the sensing plate via a predetermined air gap and disposed as a set at a predetermined interval corresponding to the interval between each recess (8b) and each projection (8a) of the sensing plate (8). With the construction, the very reliable small speed sensor having a high electromotive force, little fluctuation in the gap caused by thermal expansion, and no danger of a wire break, which does not occupy a large area, is easily installed and adjusted, and can obtain two signals having a phase difference can be realized.

Description

Specification

Speed detector Technical field

The present invention relates to a speed detector used in vehicles such as railroads and automobiles, various automatic machines, machine tools, and the like, and detects the rotational speed of a power source and other power sources. Background art

As a speed detector used in a conventional vehicle and the like, for example, a speed detector having a structure as shown in FIG. 9 is known. The speed detector shown in FIG. 9 is composed of a magnetic 'electric conversion unit 1' having a permanent magnet 2 ', a pole piece 3', and a coil 4 'wound on the pole piece 3'. A detection plate 8 that rotates in accordance with the rotation of the measurement object. Further, the end face of the pole piece 3 ′ of the magnetic 'electrical conversion section 1 ′ and the end face of the detection plate 8 are arranged so as to face each other with a predetermined gap. When the detection plate 8 rotates, the concave portion 8b and the convex portion 8a formed at the ends also move, and the concave portion 8b approaches the pole piece 3 ', or the convex portion 8a approaches. . Since the detection plate 8 is made of a magnetic material, as a result, the magnetic material approaches or separates from the pole piece 3 ′. The magnetic flux is supplied from the permanent magnet 2 ′ to the pole piece 3 ′, but the magnetic material inside the pole piece 3 ′ changes when the magnetic material approaches or separates from the end of the pole piece 3 ′ . Therefore, the magnetic flux density passing through the coil 4 ′ wound around the pole piece 3 ′ changes, and an electromotive force is generated on the coil 4 ′. This electromotive force usually appears as a sine wave or pulse wave, and its magnitude is proportional to the number of times the concave portion 8b and the convex portion 8a approach each other per unit time, that is, the rotation speed (frequency). Increase. Therefore, the rotation speed of the object can be detected by detecting the wave number (frequency) of the electromotive force from the coil 4 'and its magnitude. In addition, since these operations do not require a power supply or amplifying element, they can be used as sensors used in places where extremely high safety and reliability are required or where use under severe conditions is required. Useful.

However, since the conventional speed detector operates as a single detector with the single magnetic-electric conversion unit 1 'in this way, the rotation direction is determined by using two signals with a 90-degree phase difference using this. For this purpose, for example, two separate magnetic-electrical converters 1 ′ are prepared, and they are opposed to the irregularities on the circumference of the detection plate by the interval of T (0. SinlZA) (T: (Interval, n: integer), and it was necessary to arrange the pole piece 3 'at an angle so that the center line of the pole piece passed through the rotation axis of the detection plate. That is, as shown in FIG. 10, the magneto-electric converters 1A and IB are arranged on a mounting table 21 having a certain angle so as to appropriately face the end face of the detection plate 8. In addition, in the figure, a measuring unit case 22 and a device under test 23 are provided. In this case, it is extremely difficult to make adjustments for positioning and angle setting, and a complicated adjustment operation is required. It is also conceivable to arrange the two magnetic-electric conversion units 1 ′ close together so that the mounting angle can be ignored, but the coil 4 ′ and magnet 2 ′ of the conventional magnetic 電気 electric conversion unit 1 はIt was very difficult to get them close to such a large location.

Further, when the size of the magnetic-electrical conversion unit 1 ′ is increased, the size of the case for storing the portion is increased. It is necessary to use a non-magnetic material for the case that houses the magnetic-electric conversion unit 1 ′, but the non-magnetic case material that is usually used has a large coefficient of thermal expansion. The gap of the output fluctuates, and the output voltage also fluctuates.

In addition, it is usually stated that an electromotive force at a frequency of 30 Hz is required to be about IV in order to stably detect the electromotive force. However, there are very few conventional detectors that can obtain such an electromotive force. When approaching 1 'or trying to obtain a compact one, the number of turns of the coil was limited and the required electromotive force could not be obtained.

In order to reduce the size of the coil, it is conceivable to use a winding with a small wire diameter. However, when the wire diameter is reduced, the risk of disconnection due to vibration and impact during winding and operation increases. If a disconnection occurs during manufacturing, the yield will decrease, causing a cost increase. In addition, an inspection process for detecting such a disconnection may be required. If a disconnection occurs during operation, the operation of the speed detector will stop.If such a defect occurs in the sensor that detects the speed of the vehicle or machine, a fatal accident will occur. Can cause. Therefore, it is not practical to use a winding with a small wire diameter. Disclosure of the invention

An object of the present invention is to reduce the gap variation due to thermal expansion with a small size, to take up a small space, to easily install and adjust, to obtain two phase difference signals with one detector, and to obtain high electromotive force. An object of the present invention is to realize a speed detector having high reliability without disconnection. That is, the above object is achieved by the following configurations (1) to (7).

(1) a magnetic core having a U-shaped cross section;

Detection coils (4a, 4b) wound on the core (3) and converting changes in magnetic flux density in the core (3) into electric signals;

A magneto-electric converter (1) at the end of the core (3) and having permanent magnets (2a, 2b) for supplying magnetic flux to the core (3);

A disk-shaped magnetic body that rotates in synchronization with the object to be detected, and has, on its end face, a concave portion (8b) and a convex portion (8a) in the circumferential direction, and the concave portion (8b) Or a detection plate (8) for forming a magnetic path with the core (3) via a projection (8a), The magneto-electric converter (1) is arranged so that an end of a core (3) faces an end surface of the detection plate (8) via a predetermined gap, and a concave portion of the detection plate (8). Velocity detectors arranged as a pair at a predetermined interval corresponding to the interval between (8b) and the projection (8a).

(2) The speed detector according to (1), wherein the U-shaped cross section of the core (3) is arranged to be parallel to the axial direction of the detection plate.

(3) The speed detector according to (1) or (2), wherein the magnets at the ends of the pair of cores (3) are arranged so that the same polarity is adjacent to each other.

(4) When the mounting interval P of the core (3) is T, the interval between the convex portions of the detecting plate is T,

P = T (0.5 η soil 1 4)

(η = integer)

The speed detector according to any one of the above (1) to (3), which is represented by and is arranged within the range of {± 0.1}.

(5) The speed of any of the above (1) to (4), wherein the coils (4a, 4b) are divided and wound corresponding to the permanent magnets at each end of the core (3). Detector.

(6) The rotation of the detection plate (8) generates a voltage corresponding to a change in magnetic flux density corresponding to the concave portion (8b) and the convex portion (8a) by the rotation of the detection plate (8). The speed detector according to any one of the above (1) to (5), wherein this voltage is equal to or higher than IV when the frequency obtained by the change in the concave portion (8b) and the convex portion (8a) is 30 Hz.

(7) The speed detector according to any one of (1) to (6), wherein the magnetic-electric conversion unit (1) is housed integrally in a case. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a partial cross-sectional view showing a basic configuration of a speed detector of the present invention. FIG. 2 is a plan view showing a state where the magneto-electric conversion unit is housed in a case. FIG. 3 is an external plan view of the mounting case.

FIG. 4 is an external side view of the mounting case.

FIG. 5 is a partial sectional view showing another configuration example of the speed detector of the present invention.

FIG. 6 is a diagram showing an output waveform from the speed detector according to the embodiment of the present invention. Fig. 7 is a diagram showing the relationship between the electric / magnetic converter and the detection plate, and shows a state in which the core is arranged parallel to the rotation axis of the detection plate.

Fig. 8 is a diagram showing the relationship between the electric / magnetic converter and the detection plate, and shows a state in which the core is arranged perpendicular to the rotation axis of the detection plate.

FIG. 9 is a diagram showing a configuration of a conventional speed detector.

FIG. 10 is a diagram showing a state in which a conventional speed detector is arranged so that two phase difference signals can be extracted. BEST MODE FOR CARRYING OUT THE INVENTION

A speed detector according to the present invention includes a core that is a magnetic body having a U-shaped cross section, a detection coil that is wound on the core, and converts a change in magnetic flux density in the core into an electric signal, and an end portion of the core. A magnetic-electric conversion unit having a permanent magnet that supplies a magnetic flux to the core; and a disk-shaped magnetic body that rotates in synchronization with an object to be detected. And a detecting plate that forms a magnetic path with the core via the concave or convex portion. The magneto-electric conversion section is configured such that an end of the core has a predetermined gap therebetween. It is arranged so as to face the end face of the detection plate, and is arranged as a pair at a predetermined position corresponding to the interval between the concave portion and the convex portion of the detection plate.

By having a core having a U-shaped cross section in this way, a permanent magnet is arranged at the end of the core, and the end of the core is arranged so as to face the end face of the detection plate, so that the leakage flux is reduced. Extremely small, the magnetic flux density passing inside the core increases, and the electromotive force increases. Further, by preparing two cores and arranging them as a pair with a predetermined interval corresponding to the interval between the concave portion and the convex portion of the detection plate, two phase difference signals can be easily obtained. Also, since the two cores can be arranged close to each other, they become an integrated speed detector, which makes installation and adjustment extremely easy. It also has a strong structure in terms of strength.

By arranging a permanent magnet that supplies a magnetic flux to the core at the end of the core, manufacturing becomes easy, and the magnetic flux is efficiently supplied to the magnetic path, so that the electromotive force is improved.

The size and shape of the core are not particularly limited as long as the core has a U-shaped cross section parallel to the magnetic path, and the end can face the end face of the detection plate. The center-to-center size is about 5 to 30 mm, the depth from the end to the base is about 5 to 30 strokes, and the maximum thickness is about 3 to 15 thighs. Also, this cross section is not limited to a U-shape in a strict sense, and may be a U-shape or a shape close to a C-shape. The cross-sectional shape perpendicular to the magnetic path of the core is not particularly limited, and may be circular or square, but preferably circular (including elliptical and the like).

The material of the core is not particularly limited as long as it is a magnetic material.Preferably, a material having a high magnetic permeability such as electromagnetic soft iron, calcium steel, permalloy, ferrite, and Fe—Co alloy is preferably used. it can.

The permanent magnet provided at the end of the core is not particularly limited as long as it can supply a magnetic flux for generating a necessary electromotive force, and its size and shape are arbitrary. A column or a prism having a cross-sectional shape equal to the vertical cross-sectional shape of the core is preferable, and more preferably a shape equal to or slightly smaller than the cross-section of the core is preferable. Further, the permanent magnet needs to be arranged at least at one end of the core, but is preferably arranged at both ends of the core. As for the magnetic flux density obtained from the magnet, the detection plate was placed while attached to the core. The magnetic flux density B of the magnet surface at this time is preferably about 1000 to 500 OGauss, and particularly preferably about 2000 to 4000 Gauss. Examples of the magnet that gives such a magnetic field include Fe—Nd—B, Sm—Co, ferrite, and alnico. Among them, Fe—Nd—B and Sm—Co are preferable because a large magnetic flux density can be obtained. However, ferrite is preferred in terms of price.

Normally, cores having the same configuration are arranged as a pair in order to obtain two signals with a phase difference. The mounting interval of the cores is not particularly limited as long as the interval is such that two signals with a phase difference can be obtained.However, the signals obtained from the two magneto-electric converters have a predetermined phase difference. However, it is preferable to arrange them so that two signals having a phase difference of about 90 degrees and 36 degrees can be obtained. As a preferred embodiment, when the two cores are arranged close to each other, when the mounting pitch is P and the pitch between the concave portion and the ΰ portion of the detection plate is T, Ρ == Τ (0.5 η ± 1 // 4), and both are preferably arranged at positions within the range of {± 0.1}.

Further, when the cores are arranged as a pair, it is preferable that the magnets provided at the ends are arranged so that the same polarity is adjacent to each other, such as S poles and Ν poles, so that the magnets provided at the end portions do not overlap each other.

A coil is wound around the core for detecting a change in magnetic flux density inside the core. Preferably, the coil is divided and wound. By splitting the coil, more windings can be wound in one magnetic path. In addition, more windings can be wound around a portion having a large magnetic flux, and the electromotive force is improved. More preferably, the coil is wound close to the magnet. Since the magnetic flux is concentrated near the magnet, higher electromotive force can be obtained.

The winding used for the coil may be any wire used for ordinary coils, transformers, motors, and the like, and is not particularly limited, but preferably includes a polyurethane wire, a cement wire, and the like. be able to. Good winding wire diameter Preferably, it is 0.06-0.1 awake, more preferably, 0.07-0.09 mm. If the wire diameter is too small, there is a risk of disconnection and the resistance will increase. If it is too thick, the coil will be large. Further, the resistance of the winding is preferably equal to or less than lk Q, and more preferably about 100 to 800 Ω. When the coil is divided and wound, the number of turns is preferably 500 turns or less, and more preferably about 2000 to 400 turns. When the number of turns is large, the coil becomes large, and when the number of turns is small, the electromotive force of the coil is reduced.

The detection plate is a disk-shaped rotator that is formed of a magnetic material and rotates in synchronization with the object to be measured. At the end, concave portions and convex portions are alternately formed in a gear shape. Preferred materials for the detection plate are the same as those for the core. The size of the detection plate may be an appropriate size depending on the size of the object to be measured, the measurement accuracy, the required electromotive force, and the like, and preferably the module is 2.5 or less. Similar to the above, the number of concave portions and convex portions of the detection plate may be appropriately determined depending on required accuracy, electromotive force and other factors. It is preferably about 30 to 100, more preferably about 50 to 70. The height of the recess is preferably at least 1 corrupt, more preferably about 3 to 2 ram. The arrangement of the core with respect to the detection plate is preferably such that the U-shaped cross section of the core is parallel to the axial direction of the detection plate as shown in FIG. In other words, both ends of the core (including the magnet) are arranged at positions that simultaneously face the protrusions or recesses due to the rotation of the force detection plate. By arranging in this manner, when both ends of the core face the convex portion at the same time due to the rotation of the detection plate, the magnetic flux passing through the detection plate can be maximized. When both ends of the core face the recess at the same time due to the rotation, the magnetic flux density can be minimized by passing through the detection plate. In other words, the change in the magnetic flux density obtained by the convex and concave portions of the detection plate can be maximized, and the signal obtained from the signal has a greater amplitude than the conventional one. In this case, for example, as shown in FIG. 8, the U-shaped cross section of the core corresponds to the rotation axis of the detection plate. However, compared to the case of Fig. 7, the magnetic flux density passing through the inside of the detection plate is reduced, and the increase / decrease ratio of the magnetic flux density due to the concave portion and the convex portion is reduced. I will. Note that h in FIG. 7 indicates the height between the concave portion and the convex portion, and FIG. 7 shows a state in which the convex portion faces the magneto-electric conversion portion (the end of the core including the magnet). I have.

The shortest distance between the convex portion of the detection plate and the magnetic-electrical conversion portion (magnet), that is, the gap is preferably 0.1 to 1.5 wake, more preferably 0.5 to 0.9 mm.

Next, a more specific configuration of the present invention will be described with reference to the drawings.

FIG. 1 is a partial cross-sectional view showing a specific configuration of a speed detector of the present invention, and FIG. 2 is a plan view of a case in which a magneto-electric conversion unit is housed, as viewed from a detection plate side. In the figure, the speed detector of the present invention comprises a core 3, two magnets 2a and 2b at both ends of the core, and coils wound around both arms 3a and 3b of the core. 4 a, 4, a core mounting flange 6, and a detection plate 8.

In this example, the core 3 has a U-shaped cross section parallel to the magnetic path, and has two arms 3a and 3b extending to the ends and a base 3 connecting the two arms 3a and 3b. has c. The cross section perpendicular to the magnetic path is circular, making it easy to wind the coil. At the end of the core, columnar permanent magnets 2a and 2b each corresponding to the shape of the core are arranged. In this case, the permanent magnets 2 a and 2 b are bonded to the end of the core 3. The mounting flange 6 has four mounting holes identical in shape to the core 3, and the core 3 is fixed by inserting the arms 3a and 3b of each core 3 into these mounting holes. Then, place the two cores in the appropriate positions. In addition, the mounting flange is provided with a terminal for wiring from the coil, so that wiring can be relayed.

Coils 4 &, 4 b are attached to the arms 3 a, 3 of the core 3. The coils 4a and 4b can be wound directly around the arms 3a and 3b of the core 3, but in this example, PT / JP 8/05169

Ten

The material wound around the bins 5 a and 5 b is attached to the core 3. By dividing the coil into two parts and winding them around the arms 3 a and 3 b near the magnet 2 of the core 3, the coil becomes compact, the leakage flux decreases, and more magnetic flux is captured. Can be.

The magnetic-electrical converters 1 A and IB combined by the mounting flange 6 are housed in the case 9 as shown in FIG. 2, and the tip, that is, the tip of the magnet, is located at almost the same plane position. Is adjusted as follows. The distance from this tip to the end of the detection plate 8, that is, the tip of the projection is adjusted so that the gap is about 0.1 to 1.5 mm.

As described above, the magnetic-to-electrical converters 1A and 1B are housed in a case 9 as shown in FIG. 2, and further mounted in a fixed case 11 as shown in FIGS. The fixed case 1 1 has a mounting flange, and is mounted on a mounting table (not shown) for the DUT. In addition, it has a lid 12 and a cable fitting 13, and the cable 14 is fixed by the cable fitting 13. The material of the case 11 and the lid 12 is preferably a metal having a small coefficient of thermal expansion, such as pig iron. If the coefficient of thermal expansion is large, the gap greatly fluctuates, which may cause a failure. The case 11 has a terminal block for connection to the cable 14 .By removing the lid 12, the wiring from the magnetic-to-electrical conversion units 1 A and 1 B and the wires in the cable 14 are separated. You can connect. FIG. 5 shows another example of the configuration of the speed detector of the present invention. In this example, an auxiliary flange 7 is used in addition to the flange 6 for mounting the core. The material and shape of the auxiliary flange 7 may be the same as those of the flange 6 described above. By holding the core 3 at the two locations of the flange 6 and the auxiliary flange 7 in this manner, the core 3 can be held more reliably and with high accuracy. In this example, bobbins 5a and 5b are arranged between two flanges 6 and 7, and the bobbins 5a and 5b position the flanges. You.

By changing the mounting pitch between the two cores 3 between the flange 6 and the auxiliary flange 7, a predetermined angle between the cores 3 can be provided. In this example, a protective cover 9a made of a non-magnetic metal or the like is provided on the end of the core 3 to prevent intrusion of dust and the like. Other components are the same as those in FIG. 1, and the same components are denoted by the same reference numerals and description thereof will be omitted.

The speed detector of the present invention does not require a power supply and has a simple configuration having no amplifying element. For example, the speed detector of a vehicle such as a train or an automobile, an automatic machine, or a rotating body such as a motor or the like as a power source is used. Suitable for speed detection. In particular, they exhibit excellent performance in trains and automobiles that require extremely high safety and reliability and are used in harsh environments.

Example

A speed detector having the configuration shown in Figs. At this time, S U Y material was used for the core material, and S m—C 0 was used for the magnet. A coil wire with a wire diameter of 0.08 cm was used, and it was wound for 300 turns, and two sets of one coil were prepared and attached to the arm of each coil. . At this time, the resistance value per coil was about 250 Ω or less. As the detection plate, a gear with module = 2.5 and teeth with 60 was used, and the gap was set to 0.7.

When the output voltage at a frequency of 30 Hz was measured using the obtained velocity detector, it was 1 V or more at the peak to peak. Figure 6 shows the output waveform at this time. As is evident from the figure, the speed detector of the present invention can obtain an output of 1 V or more at the peak t0 peak and has a clean sinusoidal waveform despite its compact and integrated structure. ing. The invention's effect

As described above, according to the present invention, the size is small, the fluctuation of the gap due to thermal expansion is small, It can be installed and adjusted easily without taking up any space, can obtain two phase difference signals with one detector, and can realize a highly reliable speed detector with high electromotive force and no risk of disconnection.

Claims

The scope of the claims

1. A magnetic core having a U-shaped cross section,

A detection coil wound on the core and converting a change in magnetic flux density in the core into an electric signal;

A magnetic-electric conversion unit having a permanent magnet at the end of the core and supplying a magnetic flux to the core,

A disk-shaped magnetic body that rotates in synchronization with an object to be detected. The magnetic body has a concave portion and a convex portion on its end surface in the circumferential direction. The core and the magnetic path are connected to each other through the concave portion or the convex portion. A detection plate to be formed,

The magneto-electric conversion unit is disposed so that an end of the core faces an end surface of the detection plate via a predetermined gap, and at a predetermined interval corresponding to an interval between a concave portion and a convex portion of the detection plate. Speed detectors arranged as a pair.

2. The speed detector according to claim 1, wherein the U-shaped cross section of the core is arranged so as to be parallel to the axial direction of the detection plate.

3. The speed detector according to claim 1, wherein the magnets at the ends of the pair of cores are arranged such that the same polarity is adjacent to each other.

4. When the interval P between the cores is defined as T, the interval between the protrusions of the detection plate is T, P = T (0.5 η ± 14)

(η = integer)

The speed detector according to any one of claims 1 to 3, wherein the speed detector is represented by the following formula, and is arranged within a range of {± 0.1}.

5. The speed detector according to any one of claims 1 to 4, wherein the coil is divided and wound corresponding to a permanent magnet at each end of the core.

6. Due to the rotation of the detection plate, the magneto-electric conversion unit generates a voltage corresponding to a change in magnetic flux density corresponding to the concave portion and the convex portion, The speed detector according to any one of claims 1 to 5, wherein the voltage is 1 V or more when a frequency obtained by changing the concave portion and the convex portion is 30 Hz.

7. The speed detector according to any one of claims 1 to 6, wherein the magneto-electric converter is housed integrally in a case.