JP2004170344A - Bearing unit with sensor, and magnetism detecting method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing unit with a sensor improved in disassembling performance thereof, while restricted in deterioration of the disassembling performance even in the case of a small diameter. <P>SOLUTION: A pulser ring 3 has two layers of magnetism generating layers 8a and 8b formed with a plurality of magnetism generating parts in the circumferential direction with an equal pitch. These magnetism generating layers 8a and 8b are overlapped with each other in the radial direction so that opposite magnetic poles face to each other. The sensor device 2 is provided with a magnetic sensor 12 opposite to the pulser ring 3, a magnetism generating member 21 arranged opposite to the magnetic sensor 12 through the pulser ring 3 to generate magnetism, and a magnetism focusing member 22 for focusing magnetic flux density of the magnetism from the magnetism generating member 21 and the pulser ring 3 to lead it to the magnetic sensor 12. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing unit with a sensor and the like used in an ABS of an automobile.
[0002]
[Prior art]
BACKGROUND ART In a railway vehicle or an automobile, a rolling bearing, and a sensor device and a detection unit provided thereon are provided to support an axle or a rotating shaft that transmits rotation to the axle and detect rotation of the rotating speed and rotation angle of the axle. (For example, Patent Document 1).
[0003]
[Patent Document 1]
JP-A-2002-174258
[Problems to be solved by the invention]
In this type of rolling bearing unit with a sensor, there is a strong demand for improvement in resolution and reduction in diameter. Since the resolution depends on the number of magnetized poles of the pulsaring, it is conceivable to increase the number of poles in order to improve the resolution. In this case, however, the single pole width (pitch width) becomes smaller and the magnetic flux density becomes lower. Therefore, there is a problem that the absolute value of the signal output of the magnetic sensor becomes small and the rotation cannot be accurately detected. Also, when the diameter is reduced without changing the resolution (the number of magnetized poles), the same problem occurs because the single pole width is reduced.
[0005]
An object of the present invention is to provide a bearing unit with a sensor that can improve the resolution and does not need to reduce the resolution even if the diameter is reduced.
[0006]
Means for Solving the Problems and Effects of the Invention
A bearing unit with a sensor according to the present invention includes a bearing having an inner ring and an outer ring, a pulsar ring provided on one of the outer ring and the inner ring and having a magnetic generator, and a sensor device provided on the other side. In the unit, the pulsaring has two magnetic generating layers in which a plurality of magnetic generating parts are formed at equal pitches in the circumferential direction, and these magnetic generating layers are overlapped in the radial direction so that different magnetic poles face each other. The sensor device includes a magnetic sensor facing the pulsar ring, a magnetic generating member facing the magnetic sensor via the pulsar ring, and a magnet generating member, and a magnetic flux from the magnet generating member and the pulsar ring. And a magnetic flux collecting member that focuses the density and guides the density to the magnetic sensor.
[0007]
The magnetism generating member is, for example, a permanent magnet having one N pole and one S pole. The positional relationship between the magnetic generating member and the magnetic sensor may be such that the magnetic sensor is outside the pulsar ring and the magnetic generating member is inside the pulsar ring, or the magnetic sensor is inside the pulsar ring and the magnetic generating member is outside the pulsar ring. There may be. When the magnetic force of the pulsaring> the magnetic force of the magnetic generating member, the 0 mT line with zero magnetic flux density is located just above the middle between the peak value and the bottom value, and the magnetic force of the pulsaring = the magnetic force of the magnetic generating member. Is that the 0mT line is below just the middle between the peak value and the bottom value, and when the magnetic force of the pulsaring <the magnetic force of the magnetic generating member, the 0mT line is below the bottom value.
[0008]
The magnetic flux collecting member is made of a material having a high magnetic permeability, for example, is formed in a U-shape including an outer wall, an inner wall, and a side wall connecting these ends, and the magnetic sensor is held on one of the outer wall and the inner wall. The other side holds a magnet as a magnetism generating member.
[0009]
According to the bearing unit with the sensor of the present invention, the magnetic generating member is provided near the magnetic sensor, and the magnetic flux density generated by the magnetic generating member and the magnetic flux density generated by the magnetic generating portion of the pulsar ring are combined to form the magnetic sensor. Therefore, the absolute value of the signal output of the magnetic sensor can be increased. In the pulsaring, two magnetic generating layers are superposed in the radial direction so that different magnetic poles are opposed to each other. Therefore, the magnetic fluxes from the north pole to the south pole are radially outward and radial by the two magnetic generating layers. The magnetic flux density of the pulsar ring and the magnetic flux density from the N pole to the S pole of the magnetism generating member are combined to increase the overall output of the magnetic flux density. Furthermore, since the synthesized magnetic flux density is focused by the magnetic flux collecting member and efficiently input to the magnetic sensor, it is easy to obtain the output of the magnetic sensor according to the change of the magnetic flux density, and as a result, the signal output of the magnetic sensor is obtained. Can be increased. In this manner, the resolution can be improved, and therefore, even if the diameter of the bearing is reduced, the resolution does not need to be reduced. In addition, since the output can be increased without using an amplifier, the influence of noise due to an external magnetic field can be reduced.
[0010]
It is preferable that the sensor-equipped bearing unit according to the present invention incorporates a Hi / Lo threshold type pulse converter that turns on when the output of the magnetic sensor> HI threshold and turns off when the output of the magnetic sensor <Lo threshold.
[0011]
With this configuration, the signal width of the Hi threshold is larger than that of the plus / minus threshold type (a converter that turns on when the magnetic sensor output> plus threshold and turns off when the magnetic sensor output <minus threshold). The Lo threshold is about the same as the width, but it is not necessary to limit the Lo threshold to the minus side, so it can be provided at a position where the signal width is almost maximum (near 0 mT of the plus / minus threshold type). And the signal width of the Lo threshold can be increased. Therefore, the resolution becomes higher, and the resolution does not need to be reduced even if the diameter is reduced.
[0012]
The magnetic detection method according to the present invention provides a bearing unit with a sensor (a bearing having an inner and outer ring, a pulsar ring provided on one of the outer ring and the inner ring and having a magnetic generator, and a sensor device provided on the other side). The pulsaring has two magnetic generating layers in which a plurality of magnetic generating parts are formed at a constant pitch in the circumferential direction, and these magnetic generating layers are arranged in a radial direction such that different magnetic poles are opposed to each other. The sensor device includes a magnetic sensor facing the pulsar ring, a magnet generating member facing the magnetic sensor via the pulsar ring, and generating magnetism, and a magnetism from the magnetism generating member and the pulsar ring. And a magnetic flux collecting member for converging the magnetic flux density of the magnetic sensor to the magnetic sensor. In which turns ON, the and performs pulse conversion Hi / Lo threshold type that OFF when the output of the magnetic sensor <Lo threshold when the value.
[0013]
According to the magnetic detection method of the present invention, when compared with the method of performing the plus / minus threshold type (ON when the magnetic sensor output> positive threshold and OFF when the magnetic sensor output <minus threshold) conversion, the Hi threshold Although the signal width is substantially the same as the signal width of the plus threshold value, the Lo threshold value does not need to be limited to the minus side, so that the position where the signal width becomes almost maximum (plus / minus threshold type) (Near 0 mT), and the signal width of the Lo threshold can be widened. Therefore, higher resolution magnetic detection is possible.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0015]
FIG. 1 shows the upper half of one embodiment of a bearing unit with a sensor according to the present invention. In the following description, left and right refer to left and right in the figure.
[0016]
As shown in FIG. 1, the bearing unit with a sensor includes a rolling bearing (1) as a bearing, a sensor device (2) provided therein, and a pulsar ring (3) as a detected portion.
[0017]
The rolling bearing (1) includes an outer ring (4) that is a fixed ring, an inner ring (5) that is a rotating ring, and balls (6) that are a plurality of rolling elements disposed therebetween. Although not shown, the outer ring (4) is fixed to a housing or the like, and the inner ring (5) is fixed to a rotating shaft or the like.
[0018]
The pulsar ring (3) includes a support member (7) fixed to the inner ring (5) and a magnetized body (8) fixed to the support member (7). The support member (7) includes a small-diameter cylindrical portion (7a) fitted over the outer periphery of the inner ring (5), and a perforated disk portion (flange portion) extending radially outward from the right end of the small-diameter cylindrical portion (7a). (7b) and a large-diameter cylindrical portion (7c) extending rightward from the outer peripheral edge of the perforated disk portion (7b), and form a ring as a whole.
[0019]
An annular groove (9) is formed in the shoulder of the inner diameter at the right end of the outer ring (4).
[0020]
The sensor device (2) includes a case (11) fitted and fixed in a groove (9) provided in a shoulder of the inner diameter of the outer ring (4), and a magnetic sensor (2) provided in the case (11). 12) and signal processing means (13) for performing signal processing based on the output from the magnetic sensor (12).
[0021]
The case (11) is composed of a short cylindrical outer peripheral wall (11a) and an inner peripheral wall (11b), and a perforated disk-shaped side wall (11c) connecting these right ends to each other. The cross section of the hollow portion is substantially U-shaped. The free end (left end) of the outer peripheral wall (11a) extends leftward from the inner peripheral wall (11b), and the free end of the outer peripheral wall (11a) is tightly fitted to the shoulder at the right end of the outer ring (4). The free end of the inner peripheral wall (11b) is close to the right end face of the inner race (5).
[0022]
The signal processing means (13) is provided with a conversion device for converting the output of the magnetic sensor (12) into a pulse waveform, and this device is turned on when the magnetic sensor output> HI threshold as shown in FIG. , Hi / Lo threshold type which is turned off when the magnetic sensor output <Lo threshold.
[0023]
The pulsar ring (3) is formed by fixing a ring-shaped magnetized body (8) integrally formed so that the magnetic generating portions have an equal pitch over the entire outer peripheral surface of the support member (7).
[0024]
2 and 3 show details of the sensor device (2) and the pulsar ring (3) of the bearing unit with a sensor according to the present invention. The magnetized body (8) of the pulsar ring (3) has an N pole (N) and The magnetized layers (8a) and (8b) as two magnetic generating layers in which the S pole (S) is repeated in this order are superposed such that their N pole (N) and S pole (S) correspond. The sensor device (2) includes a magnetism generating member (21) opposed to the magnetic sensor (12) via a pulsar ring (3), the magnetism generating member (21) and the pulsaring ring (3). And a magnetic flux collecting member (22) for converging the magnetic flux density of the magnetic field from the magnetic sensor (12) and guiding the magnetic flux density to the magnetic sensor (12).
[0025]
The magnetic flux collecting member (22) is made of a high magnetic permeability material, and has an outer wall (22a) located radially outside the pulsar ring (3), an inner wall (22b) located inside the pulsar ring (3), and a side wall connecting these ends. (22c), a magnetic sensor is held on an outer wall (22a), and a permanent magnet as a magnetism generating member (21) is held on an inner wall (22b). In this embodiment, the magnetism generating member (21) is arranged so that the N pole is on the outside (the side near the pulsaring) and the S pole is on the inside (the side far from the pulsaring). In this way, a magnetic circuit for generating a magnetic flux density detected by the magnetic sensor (12) is formed by the magnetism generating member (21) and the magnetic flux collecting member (22), and the pulsar ring (3) moving near the magnetism generating member (21) is formed. ) Changes the direction of the magnetic flux of the magnetism generating member (21) and plays a role of controlling the magnetic flux density to slightly amplify it.
[0026]
Therefore, as shown in FIG. 2, at the moment when the magnetic sensor (12) is opposed to the N pole (N) of the outer magnetized layer (8a) of the pulsaring (3), the N pole is near the magnetic sensor (12). Since the magnetic flux from (N) to the S pole (S) reinforces each other, the magnetic flux density detected by the magnetic sensor (12) becomes maximum. In other words, the magnetic flux densities of the magnetism generating member (21) and the pulsaring (3) are combined and strengthened to form a single large magnetic flux (indicated by a long arrow in the figure) of the detection unit (in the figure) of the magnetic sensor (12). , The magnetic flux density to be detected increases, and the sensor output increases. Conversely, as shown in FIG. 3, at the moment when the magnetic sensor (12) faces the S pole (S) of the outer magnetized layer (8a) of the pulsaring (3), N near the magnetic sensor (12). The magnetic flux is weakened by the repulsion between the poles (N), and the magnetic flux density detected by the magnetic sensor (12) is minimized. That is, since the magnetic flux densities of the magnetism generating member (21) and the pulsar ring (3) are combined and weakened, the magnetic flux hardly passes through the detecting portion of the magnetic sensor (12), and the sensor output becomes small. Thus, the magnetic flux density generated by the magnet (21) as the magnetism generating means is increased or decreased by the magnetic flux density generated by the pulsaring (3). In the conventional type that does not use the magnetism generating member, the output voltage of the magnetic sensor (magnetic force of the detection unit) has a sine curve shape having an amplitude of +/− around 0 as shown in FIG. Then, the output on the + side is increased and the output on the-side is decreased, so that the output voltage of the magnetic sensor (12) becomes a sine-shaped curve having an amplitude only on the + side as shown in FIG. Therefore, the absolute value of the signal output can be increased, and the resolution is improved. In addition, the conversion device of the magnetic sensor (12) is of a Hi / Lo threshold type in which the magnetic sensor output is ON when the magnetic sensor output> HI threshold and is OFF when the magnetic sensor output <Lo threshold. The signal width of the Hi threshold is almost the same as the signal width of the plus threshold, as compared with the / threshold threshold type (magnetic sensor that turns on when the magnetic sensor output> plus threshold and turns off when the magnetic sensor output <minus threshold). However, since the Lo threshold does not need to be limited to the minus side, it can be provided at a position where the signal width is almost maximum (near 0 mT of the plus / minus threshold type), and the signal of the Lo threshold can be provided. It can be wider. Therefore, the resolution becomes higher, and the resolution does not need to be reduced even if the diameter is reduced.
[0027]
In FIG. 1, the pulsar ring (3) is fixed to the inner ring (5) and the sensor device (2) is provided on the outer ring (4). May be provided on the inner ring (5). The magnetic sensor may be provided inside or outside the pulsar ring, and either the north pole or the south pole of the magnetism generating member may be located on the pulsar ring side.
[0028]
The magnetized layers (8a) and (8b) as the magnetism generating layers of the pulsar ring (3) are formed by laminating two rings in the radial direction. Alternatively, it may be configured by using a pattern such as the pattern 2. In addition to the magnetic sensor (12) replacement device provided in the bearing unit, it may be provided externally to exchange signals with the magnetic sensor (12) by wire or wirelessly. In the case where it is provided inside, since the wiring is eliminated or becomes extremely short, it is hardly affected by external magnetic noise. Further, the magnetic sensor (12) and the converter may be formed as one IC (integrated circuit). In this case, it is possible to reduce the size and to be less susceptible to the influence of the noise and the like. Further, in the above embodiment, the example of the rolling bearing (1) including the rolling element (6) is described as the bearing, but the present invention can be applied to other bearings such as a sliding bearing and a dynamic pressure bearing.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing one embodiment of a sensor-equipped bearing unit according to the present invention.
FIG. 2 is a diagram illustrating an example of an arrangement of a magnetic sensor and a magnetism generating member and a magnetic flux density.
FIG. 3 is a diagram illustrating a magnetic flux density when the pulsar ring is rotated by one pitch from the state of FIG. 2;
FIG. 4 is a graph showing a change in magnetic flux density detected by a magnetic sensor of the sensor-equipped bearing unit according to the present invention;
FIG. 5 is a graph showing a change in magnetic flux density detected by a plus / minus threshold type magnetic sensor.
[Explanation of symbols]
(1) Rolling bearing (2) Sensor device (3) Pulser ring (8) Magnetized body (8a) (8b) Magnetized layer (12) Magnetic sensor (21) Permanent magnet (magnetism generating means)
(22) Magnetic flux collecting member

Claims (3)

In a bearing unit with a sensor including a bearing having an inner and outer ring, a pulsar ring provided on one of the outer ring and the inner ring and having a magnetic generator, and a sensor device provided on the other side, the pulsar ring has a plurality of magnetic members. The generating unit has two magnetic generating layers formed at equal pitches in the circumferential direction, and these magnetic generating layers are superposed in the radial direction so that different magnetic poles face each other. A magnetic sensor facing the pulsar ring, a magnetic generating member facing the magnetic sensor via the pulsar ring to generate magnetism, and focusing the magnetic flux density of the magnetism from the magnetic generating member and the pulsar ring to guide the magnetic sensor to the magnetic sensor A bearing unit with a sensor, comprising: a magnetic flux collecting member. 2. The sensor-equipped bearing unit according to claim 1, further comprising a Hi / Lo threshold type pulse converter that turns on when the output of the magnetic sensor> HI threshold and turns off when the output of the magnetic sensor <Lo threshold. A magnetic detection method using the sensor-equipped bearing unit according to claim 1, wherein a pulse conversion of a Hi / Lo threshold type in which the output of the magnetic sensor is higher than the HI threshold and the output is OFF when the output of the magnetic sensor is lower than the Lo threshold. A magnetic detection method characterized by performing.

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