JPS62235522A - rotation angle sensor - Google Patents

Abstract

PURPOSE:To prevent magnetic interference among magnetic zones and accurately detect a crank-angular position by making a rotational angle sensor wherein nonmagnetic zones are formed between a plurality of rows of magnetic zones. CONSTITUTION:The magnetic field of the magnetic zones 46, 48 and 50 of a magnet ring is applied to three Hall elements 40 provided on a sensor substrate close to body of rotation 16 that is rotated at half the number of revolutions of the crank shaft (not shown) of an internal combustion engine to produce an electromotive force. The output of the three Hall elements 40 is taken out from output terminals 72, 74 and 76 via a DC component removing circuit 66 provided with a differential amplifier 60 and a comparator circuit 70 provided with a comparator 68 to be fed to the processing circuit (not shown) of a subsequent stage. Since first and second nonmagnetic zones 54 and 56 are provided between the magnetic zones 46 and 48 and between 48 and 50, respectively, the magnetic zones 46, 48 and 50 are prevented from receiving magnetic interference with one another.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a rotation angle sensor, and more specifically to a rotation angle sensor that detects the crank angle position of an internal combustion engine of an automobile or the like.

(Prior art) Various electronic control technologies for internal combustion engines have been rapidly developing in recent years, but since control timing is important in these control technologies, the piston position of the engine, which is the reference point, It is necessary to accurately detect the crank angle.

As a conventional rotation angle sensor of this type, for example,
There is a technique described in Japanese Patent No. 7-133311.

(Problem to be Solved by the Invention) However, in this type of conventional example, a plurality of disc-shaped magnets are stacked on the circumferential surface of the rotating body in the direction of its rotational axis, and magnetization is performed in multiple rows. However, the magnetized bands are placed in close contact with each other, and there is no unmagnetized band between them, so there is a risk of magnetic interference between the magnetized bands. There is a problem in that the magnetic flux path of the magnetized belts , - is disturbed by the magnetic poles of the adjacent magnetized belts, causing a detection error and making it impossible to accurately detect the rank angle position.

In particular, if there is a non-magnetized spot in the −〇 magnetized zone, there may be problems such as the spot becoming magnetized due to the influence of the adjacent magnetized zone and producing an output in the detection means. Ta. or,
These disadvantages may be exacerbated if a highly sensitive element such as a magnetoresistive element is used as the detection means.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a rotation angle sensor that can eliminate the above-described drawbacks of the prior art, prevent magnetic interference between magnetized bands, and accurately detect the crank angle position.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a rotating body that rotates in synchronization with the rotation of the crankshaft of an internal combustion engine, and a magnetic pole number on the outer peripheral surface of the rotating body. A rotation angle sensor comprising a plurality of rows of differently magnetized magnetized bands in the direction of its rotation axis, and magnetoelectric conversion means arranged facing the rotating body,
It is an object of the present invention to provide a rotation angle sensor in which a non-magnetized zone is formed between the plurality of rows of magnetized zones. Preferably, the non-magnetized belt is configured such that its width in the rotational axis direction is larger than each of the magnetized belts.

(Function) Since a non-magnetized zone is formed between each magnetized zone, mutual magnetic interference does not occur, so there is no detection error and the crank angle position can be detected accurately. I can do it.

(Example) Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

For the sake of convenience, the overall configuration will be described with reference to FIG.
0, a national body is constituted by a housing 12 and a power distribution cap 14 screwed onto the upper end of the housing 12. Distributor 1
The rotating body 16 is rotatably housed in the internal combustion engine 0, and the rotating body 16 rotates at 1/2 the rotation speed of the crankshaft (not shown) of the internal combustion engine. Camshaft (
The magnet ring 24 is composed of a rotating shaft 20 that is connected to the rotating shaft 20 (not shown) via a screwdriver, and a magnet ring 24 that is coaxially fixed to the rotating shaft 20 via a resin 22. Rotating body 1
6 is rotatably supported in the distributor via a bearing 26, and a rotor 28 is connected to the screw 3 at its upper end.
Fixed by 0.

The magnet ring 24 is rotatably installed in a chamber 34 defined by a partition plate 32, and a sensor board 36 is placed in the chamber 34 at a predetermined distance from the outer peripheral surface of the magnet ring. is fixed to the housing 12 by screws 38. On this sensor substrate 36, three Hall elements 40, which are the magnetoelectric conversion means, are provided so as to face the magnetized bands of the magnet ring, which will be described later. In this embodiment, a Hall element is used as the magnetoelectric conversion means, but it goes without saying that the same effect can be achieved even if a magnetoresistive element or the like is used. Further, reference numeral 42 indicates an oil seal, and reference numeral 44 indicates an O-ring.

Here, the rotating body 16 will be explained in more detail with reference to FIGS. A plurality of rows of magnetized magnetic bands are formed on the surface in the direction of the rotation axis of the magnet ring, and in the case shown in the figure, three rows of a first magnetic band 46, a second magnetic band 48, and a third magnetic band 50 are formed. Each magnetized belt has an appropriate number of pairs of N-3 poles formed in its circumferential direction, and since it is assumed that the internal combustion engine to which the rotation angle sensor according to the present invention is installed is a four-cylinder engine, the first magnetized One pair is formed on the band 46, four pairs are formed on the second magnetized band 48, and 24 pairs are formed on the third magnetized band 50, each of which is formed by equally dividing the circumferential surface. In the case of the 1-magnetized belt 46, there is a pair of N-3 poles, so a non-magnetized portion 52 is formed.Also, the N-pole and S-pole do not need to have the same length in the circumferential direction. However, by forming the first and third magnetized bands at both ends of the magnet ring, it is possible to form a magnetized band on the end side. Therefore, it has the advantage of being able to prevent magnetic interference from that direction.

One of the features of the present invention is that between each of the magnetized bands 46, 48 and 50, there are non-magnetized bands that are not magnetized, in the case shown, a first non-magnetized band 54 and a second non-magnetized band 56. It has been established that
As a result, magnetic interference between the magnetized bands 46, 48 and 50 is prevented. The first magnetized zone has a non-magnetized portion 52.
However, as a result of forming a non-magnetized zone between them,
Magnetic interference can be prevented. Moreover, as a result of being able to prevent magnetic interference, each magnetized belt can maintain sufficient coercive force. Furthermore, in the present invention, in order to more effectively prevent the magnetic interference, the width 'w6' of the non-magnetized bands 54 and 56 in the direction of the rotation axis is changed to the width 'w6' of the magnetized bands 46, 48 and 50 in the same direction. It is configured to be larger than Wb'. That is,
The width of each magnetized band 46, 48, 50 is set to 5 mm-IQmm to have sufficient coercive force for detection, but the width of the non-magnetized band 54.
The width of 56 is larger than that, for example, 19 mm or more. Furthermore, since magnetic interference is related to the strength of magnetizing force,
The magnetized band is magnetized with a coercive force sufficient for detection, and with a magnetic force that does not cause magnetic interference beyond the non-magnetized band, which has a width greater than the width of the magnetized band. Note that this magnetic force becomes smaller as the number of poles increases, so it is recommended that the magnetic force be varied depending on the magnetized belt so that the output value of the three Hall elements 40 is uniform for each magnetized belt. , it is convenient because the processing circuit can be made general-purpose as will be described later.

Next, the operation of the rotation angle changer according to the present invention will be explained.

As shown in Figure 4, the crankshaft of the internal combustion engine (not shown)
A rotating body 16 that rotates at 1/2 the number of revolutions per revolution of
The three Hall elements 40 on the sensor substrate 36 provided close to the magnet rings have magnetized bands 46, 48, .
A magnetic field of 50°C is applied to generate an electromotive force. The outputs of the three Hall elements 40 respectively pass through an amplifier circuit 62 including a differential amplifier 60, a DC component removal circuit 66 including a coupling capacitor 64, and a comparison circuit 70 including a comparator 68, and then output to the output terminal ? 2.74.76 and sent to the i& stage processing circuit (not shown).

In this case, if the magnetizing force is changed during magnetization of the magnetized belt so that the same level of output is generated, the circuits 62, 66 and 70 can be used in common without changing the values of the resistances etc. that constitute them. It has the advantage that it can be used as Thus, from the first magnetized zone 46, 1 per 720 degrees of crank angle is generated.
One pulse per 180 degrees of the same angle is obtained from the second magnetized zone 48 and can be used as a cylinder TDC position signal, and the third magnetized zone 50, one pulse is obtained for every 5 degrees of the same angle and can be used for subdivided angle signals or engine rotational speed calculations, and based on this information, the internal combustion engine can be controlled with high precision.

Next, a method for manufacturing a rotation angle sensor according to the present invention will be explained with reference to FIG.

First, upper and lower molds 80 as shown in FIGS.
, 82 are prepared, and as shown in FIG.
is inserted into the lower mold 82, and the upper mold 80 is placed thereon. In this state, the injection port 84 is vertically continuous with a first passage 86 surrounding the outside of the magnet ring 24, and a second passage 88 branches off from the middle. Then, when a plastic resin 22 such as a molten phenol resin is injected from the injection port,
The resin first enters the first passage 86 formed vertically and presses the magnet ring 24 from the outside to apply compressive stress, and then fills up to the vicinity of the branching point to the second passage 88 and then enters the second passage 86. The inside of the magnet ring 24 is filled through the passage 88. In this state, the magnet ring 24 is pressed from inside and receives tensile stress, but since it is already under compressive stress from the outside, the internal and external stress is balanced and it does not break. Ferrite porcelain has brittle properties. Furthermore, although the cylindrical shape is relatively weak against tensile stress from within, this structure effectively prevents damage. Next, as shown in the figure (e), after filling with resin and leaving it to cool, it is taken out from the mold as shown in the figure ([) and the adhering resin 22a is scraped off with a lathe, etc., as shown in the figure (g). Then, by forming magnetized bands 46, 48, 50 and non-magnetized bands 54, 56 on the circumferential surface of the magnet ring, the rotating body is completed ((h) in the same figure). In addition, this resin has a coefficient of thermal expansion similar to that of the magnet ring, and has excellent heat resistance and impact resistance, such as unsaturated polyester containing glass fiber, phenolic resin, melamine resin, polyester resin, etc. Using alkyd resin, allyl resin, silicone resin, epoxy resin, polyamide resin, etc. can absorb the volume change during thermal expansion, reducing damage and cranking force9.
It never occurs. Furthermore, resins that have adhesive properties and do not lose elasticity even after curing, such as epoxy resin adhesives, phenol novolac epoxy resins, cyclic fatty acid epoxy resins, ortho-cresol porolac epoxy resins,
The use of polyester alkyl resin, polyamide resin, etc. has the advantage of increasing bonding properties, preventing fragments from scattering even in the event of breakage, and reducing output errors due to vibration resistance. In addition, although ferrite porcelain was used as the material for the magnet ring, barium oxide ferrite porcelain, alloy magnets, alloys of alnico, cobalt, rare earth elements, or plastic magnets in which these powders were dispersed in a plastic bar were also used. Also good.

6(a) and 6(b) show a second embodiment of the present invention, in which a cylindrical body 24b made of a lightweight non-magnetic material such as plastic is used instead of a magnetic ring, and a magnetic tape 9 is used.
0 is wound around the circumferential surface and magnetized, which has the advantage of being easy to manufacture, and also has the advantage of improving durability because the rotating body can be made lightweight. In this embodiment, the portion 92 where the magnetic tape 90 is not wound constitutes the non-magnetized belt.

(Effects of the Invention) The rotation angle sensor according to the present invention is configured such that a non-magnetized zone is formed between the plurality of rows of Q magnetized zones, so that magnetic interference does not occur between the magnetized zones, and further magnetic Since no interference occurs, each magnetized belt can maintain a sufficient coercive force, and therefore no detection errors occur, providing the advantage that the crank angular position can be accurately measured.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a rotating body of a rotation angle sensor according to the present invention, Fig. 2 is a side view thereof, Fig. 3 is a partial cross-sectional explanatory view of a distributor housing a rotation angle sensor, and Fig. 4 is a circuit diagram of a detection circuit, FIGS. 5(a) to (h) are explanatory diagrams showing a method for manufacturing a rotating body of a rotation angle sensor according to the present invention, and FIGS. 6(a) and 6(b) are diagrams of different types of rotating bodies. 10... Distributor, 16... Rotating body, 24... Magnet ring, 46, 48° 50
...Magnetized zone, 54.56...Non-magnetized zone Figure 1 Figure 4 Figure 5 (Q) -b (b) Figure 6 (Q) (b)

Claims (3)

[Claims] (1) A rotating body that rotates in synchronization with the rotation of the crankshaft of an internal combustion engine, and a plurality of rows of magnetized bands each having a different number of magnetic poles are formed on the outer peripheral surface of the rotating body in the direction of its rotational axis, and the rotation What is claimed is: 1. A rotation angle sensor comprising magneto-electric conversion means disposed facing a body, wherein a non-magnetized zone is formed between the plurality of rows of magnetized zones. (2) The rotation angle sensor according to claim 1, wherein the width of the non-magnetized band in the direction of the rotation axis is larger than each of the magnetized bands. (3) Claim 1 or 2, characterized in that the magnetoelectric conversion means is a Hall element or a magnetoresistive element.
Rotation angle sensor described in section.