JP2004271236A - Rotation detecting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation detecting apparatus capable of detecting the state of rotation even when a partition wall is present between a rotator and a rotation sensor, superior in mountability to a rotator case for housing the rotator, and heightening the degree of design freedom of the rotator case. <P>SOLUTION: The rotation detecting apparatus 100 is provided with a rotator 11 for generating repetitive changes in magnetic field strength in the periphery with its rotation; a magnetic impedance element 13 for converting the repetitive changes in the magnetic field strength generated with the rotation of the rotator 11 into electric signals; and the partition wall 12 separating the rotator 11 from the magnetic impedance element 13. By the magnetic impedance element 13, the rotation detecting apparatus 100 detects the state of rotation of the rotator 11 arranged separately from the partition wall 13. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rotation detection device that detects a rotation state of a rotating body, and more particularly, to a rotation detection device suitable for engine control and ABS control of a brake in a vehicle.
[0002]
[Prior art]
As a rotation detection device for detecting the rotation state of a rotating body, a rotation detection device for detecting the rotation state of a magnetic gear, which is a detection target, is disclosed in JP-A-8-304432 (Patent Document 1).
[0003]
In this rotation detecting device, a bias magnet is arranged near a magnetic gear as a detection target, and a magnetoresistive element as a rotation sensor is arranged in a bias magnetic field between the magnetic gear and the bias magnet. Under such a configuration and arrangement, the magnetic vector change of the bias magnetic field accompanying the rotation of the magnetic gear is converted into an electric signal by the magnetoresistive element, and the rotation state of the magnetic gear as the object to be detected is detected. You.
[0004]
Further, as a rotation detection device for detecting a rotation state of a rotating body, a rotation detection device for detecting a rotation state of a magnetized rotor, which is a detection target, is disclosed in JP-A-2000-46513 (Patent Document 2). I have.
[0005]
In this rotation detection device, a Hall element as a rotation sensor is arranged near a magnetized rotor as a detection target. With such a configuration and arrangement, a change in the magnetic field intensity due to the rotation of the magnetized rotor is converted into an electric signal by the Hall element, and the rotation state of the magnetized rotor, which is the object to be detected, is detected.
[0006]
[Patent Document 1] Japanese Patent Application Laid-Open No. 5-48019
[Patent Document 2] Japanese Patent Application Laid-Open No. 2000-46513
[Problems to be solved by the invention]
FIG. 5 is a schematic view showing an application example of the rotation detecting device disclosed in Patent Document 1, showing a state in which a crank sensor is mounted on an engine block.
[0009]
A crank sensor 10, which is a rotation sensor, includes a magnetoresistive element 2 and a bias magnet 3, and detects a rotation state of a gear 1, which is a magnetic gear connected to a crankshaft. An opening 90 is provided in the engine block 9 of FIG. The crank sensor 10 is mounted with its tip protruding inside the engine block 9 such that the magnetoresistive element 2 and the bias magnet 3 are arranged in the vicinity of the gear 1 that is the object to be detected.
[0010]
However, when the opening 90 is provided in the engine block 9 as shown in FIG. 5 and the tip of the crank sensor 10 is disposed inside the engine block 9, the engine design is greatly restricted. In particular, many devices have been mounted on recent engines, and it has become difficult to secure the mounting position of the crank sensor 10. For this reason, there is a demand for a rotation detecting device such as a crank sensor or a cam sensor that is mounted on an engine and that has excellent mountability to the engine and has a high degree of freedom in engine design.
[0011]
Further, there is a similar demand for a wheel rotation sensor for ABS, which is an application example of the rotation detecting device disclosed in Patent Document 2. In the wheel rotation sensor for ABS, a rotation sensor composed of a hall element is inserted into an opening provided in a wheel hub, and is arranged near a magnetized rotor that rotates the hall element. Wheels and suspensions are located near the wheel hub on which the rotation sensor is mounted, and the mounting location is narrow, making it difficult to secure a mounting location.
[0012]
As described above, in the conventional rotation detecting device, if a partition wall exists between the rotating body and the rotation sensor, the rotation state cannot be detected. Therefore, an opening is provided in the rotating body case that houses the rotating body. It is necessary to mount a rotation sensor. For this reason, the mountability of the rotation sensor is poor, and the degree of freedom in designing the rotating body case is limited.
[0013]
Therefore, the present invention can detect the rotation state even if there is a partition wall between the rotating body and the rotation sensor, is excellent in mountability to a rotating body case that houses the rotating body, and has a high degree of design freedom in the rotating body case. It is an object of the present invention to provide a rotation detecting device with an increased height.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, the rotation detecting device according to claim 1 includes a rotating body that causes a repetitive change in a magnetic field strength around the rotating body and a magnetic field strength generated due to the rotation of the rotating body. A magneto-impedance element that converts a repetitive change into an electric signal, and a partition wall that separates the rotator and the magneto-impedance element. It is characterized by detecting.
[0015]
The rotation detecting device of the present invention uses a magneto-impedance element utilizing the magneto-impedance effect. The magneto-impedance effect is a phenomenon in which the impedance to a high-frequency current changes due to a change in an external magnetic field. By applying a high-frequency current to the magneto-impedance element and converting a change in impedance generated by a change in an external magnetic field into an electric signal, an output of the magneto-impedance element can be obtained. This magnetic impedance element has higher magnetic sensitivity than conventional magnetoresistive elements and Hall elements. With such a magnetic impedance element having high magnetic sensitivity, even if there is a partition wall between the rotating body and the rotating body, the rotating impedance of the rotating body is detected by detecting a repetitive change in the magnetic field intensity generated with the rotating body. The state can be detected.
[0016]
The rotation detecting device according to claim 2, wherein the partition wall is a rotator case that covers the rotator, and the partition wall is disposed inside the rotator case by the magnetic impedance element disposed outside the rotator case. It is characterized in that the detected rotation state of the rotating body is detected.
[0017]
According to this, the magnetic impedance element as the rotation sensor can be mounted outside the rotator case without providing an opening in the rotator case. Therefore, it is possible to provide a rotation detecting device that is excellent in mountability on the rotating body case and has a high degree of freedom in designing the rotating body case.
[0018]
The invention according to claim 3 is characterized in that the rotating body is a gear-shaped gear made of a magnetic material or a material containing a magnetic material.
[0019]
A gear in the form of a gear made of a magnetic material or a material containing a magnetic material attracting a permanent magnet is usually slightly magnetized by an environmental magnetic field. For this reason, when the gear rotates, the magnetic field generated from the magnetized gear also rotates, and a repetitive change in the magnetic field intensity is caused to the surroundings. Even when the magnet is not magnetized, the irregularities of the gear shape periodically disturb the geomagnetism with the rotation of the gear, so that the magnetic field intensity repeatedly changes in the surroundings. Therefore, the rotation state of the gear can be detected by detecting the repetitive change of the magnetic field strength by the magnetic impedance element. In the rotation detecting device of the present invention, since the magnetic sensitivity of the magnetic impedance element is high, a bias magnet for applying a bias magnetic field need not be particularly used.
[0020]
According to a fourth aspect of the present invention, the two magneto-impedance elements are arranged side by side at a position that is １ ／ pitch apart from each other with respect to the rotation axis of the gear, and the difference between the two magneto-impedance elements is determined. It is characterized in that a dynamic output is detected. As a result, the non-fluctuation component of the geomagnetism common to the two magnetic impedance elements can be canceled, and the rotation state can be detected more reliably.
[0021]
As described in claims 5 and 6, the rotation detection device of the present invention is suitable for detecting the rotation state of a gear connected to a crankshaft of an engine or a cam connected to a camshaft of an engine.
[0022]
In the rotation detecting device of the present invention, it is not necessary to provide an opening for mounting a magnetic impedance element as a rotation sensor on the engine block. Therefore, the degree of freedom in designing the engine is excellent, and the degree of freedom in designing the engine on which many devices are mounted is increased.
[0023]
The invention according to claim 7 is characterized in that the rotating body is a cylindrical magnet having a center axis of a cylinder as a rotation axis and magnetic poles arranged alternately on an outer circumference of the cylinder.
[0024]
A rotating body composed of such a cylindrical magnet causes a repetitive change in the magnetic field strength around the rotating body with the rotation of the magnetic poles alternately arranged on the outer circumferential circle. Therefore, the rotation state of the rotating body can be detected by detecting the repetitive change of the magnetic field strength by the magnetic impedance element.
[0025]
According to an eighth aspect of the present invention, two of the magneto-impedance elements are arranged side by side at a pitch of 1/2 of a pitch of magnetic poles alternately arranged on the cylindrical magnet with the rotation axis of the cylindrical magnet as a center. The differential output of the two magnetic impedance elements is detected. As a result, the non-fluctuation component of the geomagnetism common to the two magnetic impedance elements can be canceled, and the rotation state can be detected more reliably.
[0026]
As described in claim 9, the rotation detecting device of the present invention is suitable for detecting the rotation state of a magnetized rotor attached to a rotating shaft of a wheel.
[0027]
The rotation detecting device of the present invention can be used for a wheel rotation sensor for ABS that detects the rotation state of a magnetized rotor attached to the rotation shaft of the wheel, and an opening for mounting the rotation sensor is provided on the wheel hub. There is no need to provide. Therefore, even for a wheel hub where wheels and suspensions are close to each other and a mounting place is narrow and it is difficult to secure a mounting place, the mountability is excellent and the degree of freedom in design is increased.
[0028]
As described in claim 10, the material of the partition wall is preferably a non-magnetic material.
[0029]
When the partition wall is made of a non-magnetic material that does not attract the permanent magnet, the repetitive change in the magnetic field intensity caused by the rotation of the rotating body is not disturbed by the presence of the partition wall. Therefore, the rotation state of the rotating body separated by the partition wall is reliably detected by the magnetic impedance element.
[0030]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0031]
(1st Embodiment)
FIG. 1 is a schematic diagram illustrating a configuration of a rotation detection device 100 according to the present embodiment.
[0032]
The rotation detecting device 100 of FIG. 1 includes a rotating body 11 that is a detection target, a rotating body case 12 that covers the rotating body 11, and a magnetic impedance element 13. The rotating body case 12 is also a partition wall separating the rotating body 11 and the magnetic impedance element 13.
[0033]
The rotating body 11 shown in FIG. 1 is a gear-shaped gear made of a magnetic material or a material containing a magnetic material. As the gear 11 rotates, a magnetic field as shown in FIGS. This causes a repetitive change in intensity around the gear 11.
[0034]
FIG. 2A shows a case where the gear 11a is magnetized. The gear 11a made of a magnetic material attracting a permanent magnet is usually slightly magnetized by an environmental magnetic field. In FIG. 2A, magnetic force lines generated by magnetization of the gear 11a are indicated by arrows. When the magnetized gear 11a rotates, the lines of magnetic force also rotate, causing a repetitive change in magnetic field strength around the gear 11a.
[0035]
FIGS. 2B and 2C show the case where the gear 11b is not magnetized. Even if the gear 11b is not magnetized, when the gear 11b rotates, the irregularities on the outer periphery of the gear shape periodically disturb the magnetic field lines of the terrestrial magnetism as shown in FIGS. 2 (b) and 2 (c). A change is effected around the gear 11b. The rotation state of the gears 11a and 11b can be detected by detecting the repetitive change of the magnetic field intensity accompanying the rotation of the gears 11a and 11b by the magnetic impedance element 13.
[0036]
The magnetic impedance element 13 shown in FIG. 1 is a magnetic detection element utilizing a magnetic impedance effect, and is made of a nickel iron (NiFe) thin film formed on a non-magnetic substrate. The NiFe thin film pattern of the magneto-impedance element 13 shown in FIG. 1 is formed in a zigzag shape by connecting a plurality of linear portions parallel to each other at predetermined intervals in a magnetic field detection direction and sequentially connecting them. A high-frequency current is applied to both ends of the NiFe thin film pattern of the magnetic impedance element 13, and the output of the magnetic impedance element 13 is obtained by converting a change in impedance generated between both ends due to a change in an external magnetic field into an electric signal. Can be
[0037]
The magnetic impedance element 13 has a much higher magnetic sensitivity than conventional magnetoresistive elements and Hall elements. Therefore, as shown in FIG. 1 and FIGS. 2A to 2C, the magnetic impedance element 13 is arranged outside the gear case 12, and the rotation state of the gears 11, 11a, 11b inside the gear case 12 is changed. It is possible to detect. The magneto-impedance element 13 detects a repetitive change in magnetic field intensity generated with the rotation of the gears 11, 11a, 11b leaked out of the gear case 12, and converts it into an electric signal. A signal processing circuit such as a drive circuit, an output detection circuit, a characteristic adjustment circuit, and an input / output circuit is provided around the magnetic impedance element 13, but is not shown for simplicity.
[0038]
The gear case 12 in FIG. 1 is also a partition wall separating the gear 11 and the magnetic impedance element 13 and is made of aluminum. As a material of the partition wall or the rotating body case, a non-magnetic metal such as copper or brass can be used. Further, a non-magnetic material other than metal such as resin and ceramics may be used. If the partition wall or the rotating body case is formed of a non-magnetic material that does not attract the permanent magnet, the repetitive change in the magnetic field strength caused by the rotation of the gears 11a and 11b shown in FIGS. 12 will not be disturbed. Therefore, even if the magnetic impedance element 13 is disposed outside the gear case 12, the rotation state of the gears 11, 11a, and 11b inside the gear case 12 can be reliably detected.
[0039]
Since the magnetic sensitivity of the magnetic impedance element 13 is high, the rotation detecting device 100 of the present embodiment does not use a bias magnet for applying a bias magnetic field.
[0040]
FIG. 3 shows a rotation detecting device 101 configured using two magnetic impedance elements.
[0041]
In the rotation detecting device 101 shown in FIG. 3, the two magnetic impedance elements 13a and 13b are arranged side by side at a half pitch of the gear 11 about the rotation axis of the gear 11. In the rotation detecting device 101, the differential outputs of the two magnetic impedance elements 13a and 13b are detected. Thereby, the non-fluctuation component of the terrestrial magnetism, which is common to the two magnetic impedance elements 13a and 13b and is indicated by the arrow in FIG. 3, can be canceled, and the rotation state can be detected more reliably.
[0042]
As described above, in the rotation detecting devices 100 and 101 of FIGS. 1 and 3, even if the partition wall 12 is present between the rotation body 11 and the magnetic impedance elements 13, 13 a and 13 b having high magnetic sensitivity. It is possible to detect the rotation state of the rotating body 11. Thus, the magnetic impedance elements 13, 13a, and 13b, which are rotation sensors, can be mounted outside the rotator case 12 without providing an opening in the rotator case 12. Therefore, the mountability to the rotating body case 12 is excellent, and the degree of freedom in designing the rotating body case 12 is increased.
[0043]
The rotation detecting devices 100 and 101 shown in FIGS. 1 and 3 of the present embodiment are suitable for detecting the rotation state of the gear 1 connected to the engine crankshaft and the cam connected to the engine camshaft shown in FIG. is there. In the rotation detection devices 100 and 101, it is not necessary to provide the engine block 9 with an opening 90 for mounting a magnetic impedance element as a rotation sensor, as shown in FIG. Therefore, the degree of freedom in designing the engine is excellent, and the degree of freedom in designing the engine on which many devices are mounted is increased.
[0044]
(Second embodiment)
In the rotation detecting device according to the first embodiment, the rotating body to be detected is a gear-shaped gear made of a magnetic material or a material containing a magnetic material. In the rotation detecting device according to the present embodiment, the rotating body, which is the object to be detected, is formed of a cylindrical magnet in which magnetic poles are alternately arranged on an outer circumferential circle. Hereinafter, the present embodiment will be described with reference to the drawings.
[0045]
FIG. 4 is a schematic diagram illustrating a configuration of the rotation detection device 102 according to the present embodiment.
[0046]
The rotation detecting device 102 in FIG. 4 includes a rotating body 21 as a detection target, a rotating body case 22 that covers the rotating body 21, and a magnetic impedance element 23, similarly to the rotation detecting apparatus 100 in FIG. .
[0047]
The rotating body 21 in the rotation detecting device 102 in FIG. 4 is a cylindrical magnet, and is a magnetized rotor in which the center axis of the cylinder is the rotation axis and the magnetic poles are alternately arranged on the outer circumference of the cylinder as shown in the figure. Lines of magnetic force having a repetitive pattern indicated by arrows in the figure are emitted from the magnetized rotor 21, and a repetitive change in the magnetic field intensity is caused around the magnetized rotor 21 with the rotation. Thus, similarly to the rotation detecting devices 100 and 101 of the first embodiment, the rotation state of the magnetized rotor 21 can be detected from outside the rotor (rotating body) case 22 by the magnetic impedance element 23.
[0048]
As in the case of the rotation detecting device 101 shown in FIG. 3, two magnetic impedance elements are arranged at positions spaced apart by 1/2 the pitch of the magnetic poles alternately arranged on the magnetized rotor 21, and these differential outputs are provided. May be detected. As a result, the non-fluctuation component of the geomagnetism common to the two magnetic impedance elements can be canceled, and the rotation state can be detected more reliably. In particular, this is effective when the magnetization of the magnetized rotor 21 as the rotating body is small and the repetitive change of the magnetic field strength brought around by the rotation is small.
[0049]
As described above, also in the rotation detecting device of the present embodiment, as shown in FIG. 4, the magnetic impedance element 23 serving as the rotation sensor is connected to the outside of the rotating body case 22 without providing an opening in the rotating body (rotor) case 22. It can be mounted on. Therefore, the mountability to the rotating body case 22 is excellent, and the degree of freedom in designing the rotating body case 22 is increased.
[0050]
Further, the rotation detection device 102 of FIG. 4 of the present embodiment is suitable for an ABS wheel rotation sensor that detects the rotation state of a magnetized rotor attached to a rotation shaft of a wheel. As described above, the rotation detecting device 102 does not need to provide an opening for mounting a rotation sensor on the wheel hub as the rotor case. Therefore, even for a wheel hub where wheels and suspensions are close to each other and the mounting place is narrow and it is difficult to secure a mounting place, the mountability is excellent and the degree of design freedom is high.
[0051]
(Other embodiments)
In the first embodiment, the rotation detecting devices 100 and 101 shown in FIGS. 1 and 3 of the present invention are used to control the rotation state of a gear 1 connected to a crankshaft of an engine shown in FIG. 5 and a cam connected to a camshaft of an engine. It has been described that it is suitable for the detection of Further, in the second embodiment, it has been described that the rotation detection device 102 of FIG. 4 of the present invention is suitable for an ABS wheel rotation sensor that detects the rotation state of a magnetized rotor attached to a rotation shaft of a wheel. . The present invention is not limited to this. According to the rotation detecting device of the present invention, for example, a repetitive change in magnetic field intensity accompanying rotation of a wheel is converted into an electric signal by a magnetic impedance element mounted in a hood or a cabin of a vehicle, It is also possible to detect the rotation state of.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating a configuration of a rotation detection device according to a first embodiment.
FIGS. 2A and 2B are diagrams showing a repetitive change in magnetic field intensity accompanying rotation of a gear. FIG. 2A shows a case where the gear is magnetized, and FIGS. 2B and 2C show a case where the gear is not magnetized.
FIG. 3 is a schematic diagram showing a rotation detecting device configured by using two magnetic impedance elements.
FIG. 4 is a schematic diagram illustrating a configuration of a rotation detection device according to a second embodiment.
FIG. 5 is a schematic view showing an application example of a conventional rotation detecting device, showing a state of being mounted on an engine block.
[Explanation of symbols]
100-102 Rotation detecting device 11, 11a, 11b Gear (rotating body)
12 Gear (rotating body) case, (partition wall)
13, 13a, 13b, 23 Magnetic impedance element 21 Magnetized rotor (rotary body)
22 Rotor (rotating body) case, (partition wall)

Claims (10)

With the rotation, a rotating body that repeatedly changes the magnetic field strength around,
A magnetic impedance element that converts a repetitive change in magnetic field strength generated with the rotation of the rotating body into an electric signal,
A partition wall separating the rotating body and the magnetic impedance element,
A rotation detecting device, wherein the magnetic impedance element detects a rotation state of a rotating body disposed with the partition wall interposed therebetween. The partition wall is a rotating body case that covers the rotating body,
The rotation detecting device according to claim 1, wherein a rotation state of a rotating body arranged inside the rotating body case is detected by the magnetic impedance element arranged outside the rotating body case. The rotation detecting device according to claim 1, wherein the rotating body is a gear-shaped gear made of a magnetic material or a material containing a magnetic material. The two magneto-impedance elements are arranged side by side at a position spaced apart by a half pitch of the gear with respect to the rotation axis of the gear,
The rotation detecting device according to claim 3, wherein a differential output of the two magnetic impedance elements is detected. The rotation detecting device according to claim 3, wherein the gear is a gear connected to a crankshaft of an engine, and the partition wall is an engine block. The rotation detector according to claim 1 or 2, wherein the rotating body is a cam made of a magnetic material or a material containing a magnetic material connected to a camshaft of an engine, and the partition wall is an engine block. apparatus. 3. The rotation detecting device according to claim 1, wherein the rotating body is a cylindrical magnet having a center axis of a cylinder as a rotation axis and magnetic poles alternately arranged on an outer circumference of the cylinder. Two of the magnetic impedance elements are arranged side by side at a pitch of 1/2 of a pitch of the magnetic poles alternately arranged on the cylindrical magnet around the rotation axis of the cylindrical magnet,
The rotation detecting device according to claim 7, wherein a differential output of the two magnetic impedance elements is detected. 9. The rotation detecting device according to claim 7, wherein the cylindrical magnet is a magnetized rotor attached to a rotating shaft of a wheel, and the partition wall is a wheel hub. 10. The rotation detecting device according to claim 1, wherein a material of the partition wall is a non-magnetic material.

Images