JP2004138597A - Magnetic encoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic encoder of simple structure having a strong magnetic characteristic, excellent in moldability and handlability, and facilitated in attaching work. <P>SOLUTION: In this magnetic encoder, a pulse string is generated by magnetic force to generate a code. A magnetic ring 1 formed and polarized as a magnetic single body is bondedly fixed to a reinforcement ring 3 via an adhesive 2 to form the multipolar magnetic encoder. The strong magnetic force is obtained thereby, a size and a weight are reduced thereby, and productivity is enhanced to be provided at a low cost. In the magnetic encoder proposed concurrently, the magnetic ring 1 polarized with S/N poles alternately in circle is foldedly bent in an end edge 33 of the reinforcement ring 3, and caulkedly fixed onto the reinforcement ring 3. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic encoder having strong magnetic properties, excellent rigidity, and superior productivity and price. The present invention also relates to a magnetic encoder that can be easily attached to a reinforcing ring, and that does not cause a distortion, a gap, a deformation, or the like due to a difference in coefficient of thermal expansion between the magnetic ring and the reinforcing ring, or damage when foreign matter is mixed.
[0002]
[Prior art]
Conventionally, a magnetic encoder made of an elastic rich rubber material having magnetism in consideration of breakage due to foreign object biting, shape distortion, etc. has been mainly used. The powder is mixed, put into a mold together with a reinforcing ring, heated and compressed to form a vulcanized adhesive.
[0003]
As the magnetic powder used here, ferrite magnetic powder is generally employed. For example, a rare earth magnetic material is not suitable for mixing into a rubber material because kneading workability and moldability are poor and cost is high. It has not been generally adopted.
[0004]
A magnetic encoder formed by vulcanization adhesion by mixing ferrite has excellent formability, but has a small magnetic force, and has a property that magnetic flux density varies due to the orientation of magnetic powder.
[0005]
In order to reduce the variation in the magnetic flux density, the direction of the magnetic powder must be adjusted in advance at the dough stage or in the forming stage (for example, see Patent Document 1).
[0006]
[Patent Document 1]
JP-A-2002-333033 [Problems to be solved by the invention]
As described above, a magnetic encoder made of a ferrite-based bonded magnet formed by mixing ferrite magnetic powder needs to be highly filled with ferrite in order to have practical magnetic characteristics, and thus the physical properties of rubber are significantly reduced. In addition to the above problem, the magnetic encoder is also vulcanized and bonded in a mold, and thus has a problem in that it requires labor.
[0007]
Further, in order to alleviate the disadvantage that the magnetic flux density varies on the circumference of the magnetic encoder, there is a problem that a troublesome method such as blending various kinds of ferrite or increasing the adjustment molding process is required.
[0008]
Accordingly, an object of the present invention is to provide a magnetic encoder having strong magnetic characteristics, excellent in handleability and practical in price as a result of various investigations and magnetic property tests.
[0009]
Another object of the present invention is that, even if the magnetic ring is not a magnetic simple substance but is formed by mixing a binder with magnetic powder, the mounting operation to the reinforcing ring is easy, and the magnetic ring It is an object of the present invention to provide a magnetic encoder in which there is no fear of gaps, distortions and deformations, and damage when foreign matter is mixed even if there is a difference in thermal expansion coefficient between the ring and the reinforcing ring.
[0010]
[Means for Solving the Problems]
To achieve the above objective,
A magnetic encoder according to a first aspect of the present invention is a magnetic encoder that is used for a wheel shaft and generates a pulse code by a magnetic force. After the magnetic ring is bonded to a reinforcing ring fixed to the wheel shaft side via an adhesive, The S and N poles are alternately magnetized.
[0011]
As an adhesive for fixing the magnetic ring to the reinforcing ring, an elastic silicone sealant may be used. Such an adhesive has cushioning properties, and there is a difference in thermal expansion coefficient between the magnetic ring and the reinforcing ring. Even when it is large, the difference in thermal expansion coefficient can be absorbed, so that the occurrence of gaps, distortions and deformations can also be prevented.
[0012]
A magnetic encoder according to a second aspect of the present invention is a magnetic encoder that is used for a wheel shaft and generates a pulse code by a magnetic force. After the magnetic ring is bonded to a reinforcing ring fixed to the wheel shaft side via an adhesive, In this configuration, the S and N poles are alternately magnetized, and the edge of the reinforcing ring is bent, and the magnetic ring is caulked and fixed to the reinforcing ring.
[0013]
In this case, since the magnetic ring is caulked and fixed to the reinforcing ring in place of the adhesive of claim 1, the adhesive is unnecessary, and the production is further facilitated while obtaining the same effect as in claim 1. be able to.
[0014]
In any of claims 1 and 2, a plastic magnet formed by mixing a binder with a magnetic powder such as a magnetic simple substance or ferrite can be used as the magnetic ring. In the case of using the former magnetic ring, not only the manufacturing is easy, but also a high magnetic force can be obtained, the magnetization can be easily performed, the strength is sufficient, and the handling property is extremely excellent. Therefore, magnetic encoders with high pulse generation capability can be provided at low cost, and this powerful magnetic force can take a large gap between the magnetic encoder and sensor, so that the assembly tolerances can be set roughly. Therefore, the magnetic encoder can be reduced in size and weight, and can be provided at a low price with high productivity.
In the case of using the latter magnetic ring, the thickness and shape of the magnetic ring can be arbitrarily set, and a lightweight magnetic encoder can be obtained (claims 3 and 4).
[0015]
In the magnetic encoder according to claims 6 and 7, the magnetic ring is wrapped with a protective cover made of a non-magnetic material, and the protective cover is caulked and fixed to the reinforcing ring, so that the adhesive is not used. The magnetic ring can be protected from a cause such as contact or collision with an external factor without magnetically affecting the magnetic sensor.
[0016]
In the magnetic encoder according to the eighth aspect, since the cushion material is accommodated between the magnetic ring and the protective cover, this cushion material can be used even when an inadvertent pressure is applied during assembly or foreign matter is caught. Can be protected by the buffering action.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, a magnetic ring composed of a magnetic simple substance or a magnetic ring formed by mixing a binder with magnetic powder is applied. However, the former has a large pulse generation capability and sufficient strength. The magnetic encoder can be provided at low cost. In this case, a cast magnet, a sintered magnet, or the like can be selected as a magnetic simple substance, and ferrite, rare earth, MK steel, alnico, or the like is adopted as a material for forming the magnet.
[0018]
In a preferred embodiment of such a magnetic encoder, the magnetic ring is directly attached to the reinforcing ring by an adhesive to form the magnetic encoder, and the magnetic encoder can be reduced in size and weight by the high magnetic force, which is a characteristic of the magnetic encoder. The accuracy can be dramatically increased.
[0019]
In either case, the magnetic ring is formed by bonding a magnetic simple substance or magnetic powder mixed with a binder to the reinforcing ring through an adhesive, and then magnetizing the S and N poles. Since it is formed, there is no variation or error in the output accuracy of the magnetic pulse signal due to the displacement of the mounting position of the magnetic ring to the reinforcing ring.
[0020]
Next, an embodiment of the magnetic encoder of the present invention will be described with reference to the accompanying drawings.
[0021]
FIG. 1 is a sectional view showing an embodiment of a magnetic encoder according to the first aspect of the present invention, FIG. 2 is an embodiment with a protective cover attached, and FIG. 3 is a sectional view of the embodiment incorporated in a sealing device. Yes.
[0022]
In the present invention, the magnetic ring 1 is applied with an adhesive 2 such as cyano, epoxy, phenol, rubber, or urethane, and fixed and integrated with the reinforcing ring 3 to complete the magnetic encoder. If a silicon sealant is used as the adhesive 2 used in this case, the adhesive 2 functions as a cushioning material in addition to preventing the occurrence of gaps, distortion and deformation after being firmly integrated.
[0023]
On the other hand, if the reinforcing ring 2 that supports the magnetic ring 1 is made of a plate made of a magnetic material such as cold rolled steel plate (SPCC) or SUS430, the magnetic field can be expanded and the magnetic force can be further increased.
[0024]
In the case of using a rusty material such as neodymium, iron, boron / samarium, nitrogen for the magnetic ring 1, it is a good idea to paint or plate the surface, and in order to protect it from splashed water and foreign matter, FIG. As shown, the magnetic ring 1 is wrapped with a protective cover 4 made of a nonmagnetic material (aluminum, plastic, nonmagnetic austenitic stainless steel such as SUS304, SUS301, etc.).
[0025]
FIG. 2 shows an example in which the protective cover 4 is attached.
[0026]
As shown in FIG. 2, the protective cover 4 has an end portion that is extended and bent and caulked and fixed, or a portion that engages with each other is provided and integrated and fixed (not shown). At this time, in order to protect against external stress enveloping the magnetic ring 1, if a cushion material 5 is disposed between them as shown in FIG. A buffering effect by biting can also be expected.
[0027]
As such a cushioning material 5, a relatively soft material such as a rubber material, a plastic material, a cloth material, a non-woven fabric, or a paper material can be used.
[0028]
1 and 2, the magnetic encoder is used as a single unit, but as shown in FIG. It can be used by being assembled into a sealing device (described later) combined with another fixing member 7.
[0029]
Next, as a preferred embodiment of the present invention, an example incorporated in a sealing device will be described.
[0030]
4 to 6 show an example in which the sealing device is applied to a wheel shaft bearing unit.
[0031]
4 is a schematic cross-sectional view showing the entire structure of the bearing unit incorporating the seal device to which the magnetic encoder A (# 1) shown in FIG. 1 is attached, and FIG. 5 is a diagram showing the magnetic encoder A shown in FIG. FIG. 6 is a cross-sectional view of the main part of the sealing device to which the magnetic encoder A (# 3) shown in FIG. 3 is attached.
[0032]
As described above, these magnetic encoders A (# 1) to A (# 3) are not limited to those composed of a single magnetic substance, and may be formed by mixing a magnetic powder with a binder. Good.
[0033]
The wheel shaft seals the inner member 10 and the outer member 20, the plurality of rolling elements 30 accommodated between the inner and outer members 10, 20, and the end annular space between the inner and outer members 10, 20. A magnetic encoder A (# 1) (described later) according to the present invention is attached to one side of the sealing device 50, and the magnetic encoder A (# 1) By facing the magnetic ring 1 and arranging the magnetic sensor 8 as shown in FIG. 4, a rotary encoder for detecting the wheel rotational speed is configured.
The inner member 10 and the outer member 20 of the bearing unit have raceway surfaces 10a and 20a of the rolling elements 30, and each raceway surface 10a and 20a is formed in a groove shape.
[0034]
The inner member 10 and the outer member 20 are members on the inner peripheral side and the outer peripheral side that are rotatable with respect to each other via the rolling elements 30, but even if the bearing inner ring and the bearing outer ring are independent, An assembly member in which these bearing inner ring or bearing outer ring and another part are combined may be used.
[0035]
The inner member 10 may be a shaft, and the rolling element 30 is made of a ball or a roller. In this example, a ball is used.
[0036]
The wheel shaft is a double-row rolling bearing, more specifically, a double-row angular contact ball bearing. The bearing inner ring has a pair of split inner rings 10A formed with raceway surfaces 10a and 10a of the respective rolling element rows. , 10B. The inner rings 10 </ b> A and 10 </ b> B are fitted to the outer periphery of the shaft portion of the hub wheel 60 and constitute the inner member 10 together with the hub wheel 60.
[0037]
The inner member 10 is integrated with the hub wheel 60 and one inner ring 10B instead of the three-part assembly composed of the hub wheel 60 and the pair of split inner rings 10A and 10B as described above. It is good also as what consists of two components comprised by the hub ring with a track surface, and the other inner ring | wheel 10A.
[0038]
One end (for example, an outer ring) of the constant velocity universal joint 70 is connected to the hub wheel 60, and a wheel (not shown) is attached to the flange portion 60 a of the hub wheel 60 with a bolt 80.
[0039]
70 is a constant velocity universal joint, and the other end (for example, inner ring) is connected to a drive shaft (not shown). The outer member 20 includes a bearing outer ring and is attached to a housing (not shown) including a knuckle or the like in the suspension device. The rolling elements 30 are held by a holder 40 for each row.
[0040]
The magnetic encoder A (# 1) of the present invention is provided in one seal device 50 of the wheel shaft having such a structure, and generates a pulse code by magnetic force. Here, the magnetic ring 1 constitutes the magnetic encoder A (# 1) together with the reinforcing plate 3, and magnetic poles N and S are alternately formed in the circumferential direction. The magnetic poles N and S are formed to have a predetermined pitch in the pitch circle diameter (PCD).
[0041]
As shown in the partially enlarged view in FIG. 1, the sealing device 50 includes a reinforcing ring 3 and a fixing member 7 that are respectively attached to the inner member 10 and the outer member 20, and these reinforcing ring 3 and fixing member. 7 is formed in a L-shaped cross section composed of cylindrical portions 31 and 71 and standing plate portions 32 and 72, respectively, and is disposed so as to face each other. In the embodiment, the reinforcing ring 3 has its standing plate portion 32 disposed on the outer side of the bearing, and further, the magnetic ring 1 is attached to the outer side surface via the adhesive 2 to function as a slinger. However, a sealing member 9 is vulcanized and integrated with the other fixing member 7.
7 and 8 are schematic cross-sectional views of still another sealing apparatus incorporating the magnetic encoders A and B according to the present invention.
[0042]
In these figures, members common to those in FIGS. 1 to 6 are denoted by the same reference numerals, and description thereof is omitted.
[0043]
The magnetic encoder A shown in FIG. 7 is characterized in that the magnetic ring 1 is directly crimped to the reinforcing ring 3 in order to eliminate the need for the adhesive 2 in FIG. Specifically, since the end edge of the standing plate portion 32 of the reinforcing ring 3 is hooked to the magnetic ring 1 and the end thereof is crimped 33, an adhesive as shown in FIG. The same effect as the magnetic encoder described above can be obtained.
[0044]
Further, the magnetic encoder B shown in FIG. 8 press-fits the inner ring 10 with the reinforcing ring 2 to which the magnetic ring 1 is fixed and the protective cover 3 fitted therein, while the outer member 20 has a seal. The fixing member 7 to which the member 9 is fixed is press-fitted. In the illustrated example, a gap g is formed between the reinforcing ring 2 and the cover 4, but when the protective cover 4 is fitted into the reinforcing ring 2 by forming such a gap g, The contact with the magnetic ring 1 is avoided so as not to be damaged.
[0045]
In both of these magnetic encoders A and B, the magnetic ring 1 is configured by being fixed to the reinforcing ring 2 with the adhesive 2 and then alternately magnetizing S / N poles in the circumferential shape. . Therefore, even if the mounting position of the magnetic ring 1 on the reinforcing ring 3 is deviated, there is no variation or error in the output accuracy of the magnetic pulse signal. Also in these examples, using a cushioning sealant for the adhesive, or using a cushioning material between the reinforcing ring and the protective cover, applies inadvertent pressure during assembly, or bites foreign matter. Even if there is, buffering effect can be expected.
[0046]
【The invention's effect】
In any of the magnetic encoders according to claims 1, 3, 4 to 6, in any case, the magnetic ring is a magnetic simple substance or a magnetic powder formed by mixing a binder into a reinforcing ring via an adhesive. After bonding, the S and N poles are magnetized around the circumference, so that there is no variation or error in the output accuracy of the magnetic pulse signal due to the displacement of the mounting position of the magnetic ring to the reinforcing ring. .
[0047]
Here, as an adhesive for fixing the magnetic ring to the reinforcing ring, there is a cushioning property when an elastic silicone sealant is used, and even when the difference in coefficient of thermal expansion between the magnetic ring and the reinforcing ring is large. The thermal expansion coefficient difference can be absorbed. Therefore, it is possible to prevent a gap, distortion or deformation from occurring between the magnetic ring and the reinforcing ring.
[0048]
Further, in the magnetic encoder according to claim 2, after the magnetic ring is bonded to the reinforcing ring fixed to the wheel shaft side via an adhesive, the S / N poles are alternately magnetized in the circumferential shape, The edge of the reinforcing ring is bent and the magnetic ring is caulked and fixed to the reinforcing ring.
[0049]
In this case, the magnetic ring is made of magnetic substance or magnetic powder mixed with a binder and bonded to the reinforcing ring via an adhesive, and then the S and N poles are magnetized around the circumference. Therefore, there is no variation or error in the output accuracy of the magnetic pulse signal due to the displacement of the mounting position of the magnetic ring to the reinforcing ring. In addition, since the caulking is fixed in place of the adhesive of claim 1, the adhesive is unnecessary, and the production can be further facilitated while obtaining the same effect as in claim 1.
[0050]
In the present invention, in any one of the first and second aspects, the magnetic ring is formed by magnetizing a single magnetic substance and alternately magnetizing S / N poles in the circumference, and mixing a binder with magnetic powder such as ferrite. A molded plastic magnet can be applied. In the case of using the former magnetic ring, not only the manufacturing is easy, but also a high magnetic force can be obtained, the magnetization can be easily performed, the strength is sufficient, and the handling property is extremely excellent. Therefore, a magnetic encoder having a large pulse generation capability can be provided at low cost. This powerful magnetic force makes it possible to increase the gap between the magnetic encoder and the sensor, and can set the assembly tolerance roughly, making the magnetic encoder smaller, lighter, high productivity, and low price. It can be provided by. In the case of using the latter magnetic ring, the thickness and shape of the magnetic ring can be arbitrarily set, and a lightweight magnetic encoder can be obtained.
[0051]
Further, in any case, the magnetic ring is formed by bonding a magnetic simple substance or magnetic powder mixed with a binder to the reinforcing ring via an adhesive, and then magnetizing the S and N poles. As a result, even if the mounting position of the magnetic ring to the reinforcing ring is displaced, there is no variation or error in the output accuracy of the magnetic pulse signal.
[0052]
In the magnetic encoder according to claims 6 and 7, the magnetic ring is wrapped with a protective cover made of a nonmagnetic material, and the protective cover is caulked and fixed to the reinforcing ring, or the protective cover is fitted into the reinforcing ring and fixed. Therefore, the magnetic ring can be protected from causes such as contact or collision with an external factor without magnetically affecting the magnetic sensor.
In addition, since the protective cover is fixed by caulking, a simple structure can be achieved without using an adhesive or the like.
[0053]
In the magnetic encoder according to the eighth aspect, since the cushion material is accommodated between the magnetic ring and the protective cover, this cushion material can be used even if an inadvertent pressure is applied during assembly or a foreign object is caught. Can be protected by the buffering action.
[0054]
As described above, the present invention can obtain a higher magnetic force than an elastic magnet material formed by vulcanization and bonding using conventional ferrite magnetic powder, and can produce a single magnetic force even in a multipole magnet encoder having a large number of poles. Since it can be kept large, the magnetic force sensing by the sensor is made safe and reliable.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a magnetic encoder of the present invention.
FIG. 2 is a cross-sectional view showing another example of the magnetic encoder of the present invention.
FIG. 3 is a cross-sectional view showing still another example of the magnetic encoder of the present invention.
FIG. 4 is a schematic cross-sectional view showing the overall structure of a bearing unit incorporating a seal device to which the magnetic encoder (FIG. 1) of the present invention is attached.
FIG. 5 is a cross-sectional view of an essential part showing another example of the sealing device to which the magnetic encoder (FIG. 2) of the present invention is attached.
FIG. 6 is a cross-sectional view of an essential part showing still another example of the sealing device to which the magnetic encoder of the present invention (FIG. 3) is attached.
FIG. 7 is a schematic cross-sectional view showing still another embodiment of the sealing device to which the magnetic encoder of the present invention is attached.
FIG. 8 is a schematic cross-sectional view showing still another embodiment of the sealing device to which the magnetic encoder of the present invention is attached.
[Explanation of symbols]
A (# 1) to A (# 3), A, B Magnetic encoder 1 Magnetic ring 2 Adhesive 3 Reinforcement ring 4 Protective cover 5 Cushion material 6, 33 Caulking fixing 7 Fixing member

Claims (8)

In a magnetic encoder that is used for a wheel shaft and generates a pulse code by magnetic force,
A magnetic encoder comprising: a magnetic ring bonded to a reinforcing ring fixed to a wheel shaft side through an adhesive; and S and N poles are alternately magnetized around the circumference. In a magnetic encoder that is used for a wheel shaft and generates a pulse code by magnetic force,
After the magnetic ring is bonded to the reinforcing ring fixed to the wheel shaft side via an adhesive, the S and N poles are alternately magnetized around the circumference, and the edges of the reinforcing ring are bent, and the magnetic ring The magnetic encoder is characterized in that the structure is fixed to the reinforcing ring by caulking. In either claim 1 or 2,
The magnetic ring is a magnetic encoder composed of a single magnetic material. In claim 1 or 2,
The magnetic ring is a magnetic encoder composed of a base material formed by mixing magnetic powder such as ferrite with a binder such as rubber or resin. In claim 1 or 3,
The magnetic encoder is characterized in that the adhesive is a silicon sealant. In any one of Claims 1-5,
The magnetic encoder is characterized in that the magnetic ring is further wrapped with a protective cover made of a non-magnetic material, and the protective cover is caulked and fixed to the reinforcing ring. In any one of Claims 1-5,
The magnetic encoder is characterized in that the magnetic ring is further wrapped with a protective cover made of a non-magnetic material, and the protective cover is fixedly fitted into the reinforcing ring. In claim 6,
A magnetic encoder, wherein a cushion material is accommodated between the magnetic ring and the protective cover.

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