JP2005181209A - Rotating body phase angle detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phase angle detection device for a rotating body that can always detect the phase angle of a first rotating body with respect to a second rotating body without depending on the number of rotations.
SOLUTION: A magnet 3 that rotates in conjunction with a camshaft 2 and a magnet 3 that rotates in conjunction with a crankshaft on the same axis of the magnet 3 and a facing area changes according to a relative rotational position with respect to the magnet 3. The second yokes 8 and 9 and the rotational positions of the first and second yokes 8 and 9 are opposed to each other with the same area, and a magnetic path is formed between the first and second yokes 8 and 9. The third and fourth yokes 10 and 11 and the Hall element 14 for converting the magnetic flux density between the third and fourth yokes 10 and 11 into a voltage value are provided.
[Selection] Figure 1

Description

  The present invention relates to a phase angle detection device for a rotating body that detects a phase angle of a first rotating body with respect to a second rotating body.

  2. Description of the Related Art In recent years, a valve timing control device that can change the valve timing for intake and exhaust of a cylinder has been adopted in an internal combustion engine (hereinafter referred to as “engine”). This valve timing control device has a phase change actuator that changes the phase angle of the camshaft with respect to the crankshaft of the engine, and a phase angle detection device that detects the phase angle of the camshaft with respect to the crankshaft. Accordingly, the relative phase of the camshaft is controlled.

  FIG. 6 shows a conventional example of the phase angle detection device (see, for example, Patent Document 1). The phase angle detection device 50 rotates integrally with a crankshaft (not shown), and is disposed opposite to the crank sensor plate 51 provided with a protrusion (not shown) at one location. The cam angle plate 52, a cam sensor plate (not shown) that rotates in conjunction with the camshafts 53 and 53 and has a protrusion (not shown) at one location, and the cam sensor plate There are provided cam angle sensors 54, 54 arranged opposite to each other, and an engine control unit 55 for calculating a phase difference from outputs of the crank angle sensor 52 and the cam angle sensors 54, 54.

The phase angle of the camshafts 53 and 53 relative to the crankshaft is detected from the detection outputs of both the crank angle sensor 52 and the cam angle sensors 54 and 54.
JP 2002-227668 A

  However, in the conventional phase angle detection device 50, both the crank angle sensor 52 and the cam angle sensors 54 and 54 can obtain only one output per one rotation of the crank sensor plate 51 and the cam sensor plate. Accordingly, the time resolution is high because the time required for one rotation is short when the engine is rotating at high speed, but the time resolution is low because the time required for one rotation is long when the engine is rotating at low speed. In recent exhaust regulations, precise valve timing control is required immediately after the engine is started, and it has been difficult for the conventional phase angle detection device 50 to perform such precise valve timing control.

  It should be noted that a phase angle detection device that can always detect the phase angle without depending on the rotational speed of the rotating body other than that used for the valve timing control device of the engine is desired.

  The present invention has been made in view of the circumstances described above, and an object of the present invention is to provide a phase angle of a rotating body that can always detect the phase angle of the first rotating body with respect to the second rotating body without depending on the rotational speed. It is to provide a detection device.

  In order to achieve the above object, the invention according to claim 1 is directed to a magnet that rotates in conjunction with a first rotating body, and rotates in conjunction with the second rotating body on the same axis as the magnet. The magnetic detection means whose opposed area changes according to the relative rotational position of the magnetic detection means, and the magnetic detection means are arranged opposite to each other in the same area with respect to all rotational positions of the magnetic detection means, and a magnetic path is formed between the magnetic detection means and the magnetic detection means. It is intended to include a magnetic transmission means and a magnetoelectric conversion means for converting the magnitude of a magnetic force line passing through the magnetic transmission means into an electric quantity.

  According to a second aspect of the present invention, in the phase angle detection device according to the first aspect, the magnetic detection means is a first yoke and a second yoke that are arranged to face the magnet in a radial direction, and The magnetic transmission means is configured to be a third yoke and a fourth yoke provided coaxially with the first yoke and the second yoke and with the magnetoelectric conversion means interposed therebetween.

  Further, the invention according to claim 3 is the phase angle detection device according to claim 2, wherein the third yoke has a constant axial gap with respect to the first yoke, and the fourth yoke. The yokes are arranged with a certain length of radial gap with respect to the second yoke.

  Furthermore, the invention according to claim 4 is the phase angle detection device according to claim 1, wherein the first rotating body is a camshaft, and the second rotating body is a crankshaft. The camshaft is configured to detect the rotational phase difference of the camshaft.

  According to the first aspect of the present invention, when a rotational phase angle is formed between the magnet that is interlocked with the rotation of the first rotating body and the magnetic detection means that is interlocked with the rotation of the second rotating body, the rotational phase angle is determined according to the rotational phase angle. Both opposing areas change, and a magnetic flux according to this opposing area always flows to the magnetic transmission means at all rotational positions via the magnetic detection means, and the magnitude of this magnetic flux is output as an electric quantity by the magnetoelectric conversion means The magnetoelectric conversion means always detects the phase angle without depending on the rotation period of the first rotating body and the second rotating body.

  According to the invention of claim 2, since the magnetic flux state at the position of the magnetoelectric conversion means can be stabilized by the third and fourth yokes, very accurate phase angle information can be obtained.

  According to the third aspect of the present invention, the air gap between the first yoke and the third yoke and the air gap between the second yoke and the fourth yoke do not change at all rotational positions of the first yoke and the second yoke. Accurate phase angle information can be obtained.

  According to the invention of claim 4, it can be obtained when detecting the rotational phase angle of the camshaft with respect to the crankshaft.

  Hereinafter, an embodiment embodying the present invention will be described with reference to the drawings.

  1 to 5 show a case where the phase angle detection device of the present invention is used in an engine valve timing control device, FIG. 1 is a sectional view of the phase angle detection device, and FIG. 2 is an oblique view of the phase angle detection device. FIG. 3 is a perspective view of the main part viewed obliquely from the lower side of the phase angle detection device, and FIG. 4 is a diagram showing the arrangement state of the magnet and the first and second yokes at the phase angle of 0 degree. FIG. 5 is an output characteristic diagram of the Hall element.

  1 to 3, the phase angle detection device 1 includes a magnet 3 fixed on the upper surface of a camshaft 2 that is a first rotating body, and the magnet 3 has a rotational center C in conjunction with the camshaft 2. Rotate to center. The magnet 3 is formed, for example, in a disk shape (or D-cut shape), and has a pair of magnetized surfaces 3a and 3b (shown in FIG. The S pole is magnetized on one of the magnetized surfaces 3a, and the N pole is magnetized on the other magnetized surface 3b.

  The timing belt 5 has one end hung on a pulley (not shown) on the crankshaft side that is a second rotating body, and the other end is hung on the sprocket 6. The sprocket 6 rotates around the rotation center C of the camshaft 2 as a rotation center (that is, a coaxial center), and a cylindrical and nonmagnetic yoke housing 7 is fixed to the upper surface of the sprocket 6. A first yoke 8 and a second yoke 9 which are magnetic detection means are fixed to the yoke housing 7.

  The first yoke 8 has a fan angle of about 90 degrees with the rotation center C as the center, and a first arcuate surface portion 8a disposed through a gap of a certain length L1 in the radial direction with respect to the magnet 3; The arm portion 8b is connected to the first arcuate surface portion 8a, and the disk-shaped magnetic force line output portion 8c is fixed to the tip of the arm portion 8b and disposed on the axis of the rotation center C.

  Similar to the first arcuate surface portion 8a, the second yoke 9 has a fan angle of about 90 degrees with respect to the rotation center C, and is arranged with a gap of a certain length L1 in the radial direction with respect to the magnet 3. A second arcuate surface portion 9a is provided, and the upper end of the second arcuate surface portion 9a is disposed close to a fourth yoke 11 described below. The second arcuate surface portion 9a of the second yoke is disposed at a position opposite to the first arcuate surface portion 8a of the first yoke 8 at an angle of 180 degrees with the rotation center C as the center.

  The third yoke 10 and the fourth yoke 11 serving as magnetic transmission means are fixed to a bracket 13 fixed to a non-magnetic front cover 12. The third yoke 10 has a small disk shape and is fixed to the lower surface of the bracket 13 in a suspended state. The third yoke 10 is fixed with the center of rotation C of the first and second yokes 8 and 9 as a disk-shaped center, and has an axial gap of a certain length L2 with respect to the first yoke 8. Are arranged. That is, the third yoke 10 and the first yoke 8 have the same facing area with respect to all the rotational positions of the first yoke 8 and are disposed to face each other with a constant interval L2.

  The fourth yoke 11 has a large disk shape and is fixed inside the bracket 13. Similarly to the third yoke 10, the fourth yoke 11 is also fixed with the rotation center C of the first and second yokes 8 and 9 as a disk-shaped center, and a radial gap having a constant length L3 with respect to the second yoke 9. Are arranged. That is, the fourth yoke 11 and the second yoke 9 have the same facing area with respect to all the rotational positions of the second yoke 9 and are disposed so as to face each other with a constant interval L3.

  The Hall element 14 that is a magnetoelectric conversion means is fixed by a hole holding member 20 at a position between the third yoke 10 and the fourth yoke 11, and an axial magnetic flux between the third and fourth yokes 10, 11. The density is detected, and a voltage corresponding to the detected magnetic flux density is output. The output of the Hall element 14 is led to the outside of the bracket 13 via the cable 15.

  Next, the positional relationship between the magnet 3 and the first arc surface portion 8a of the first yoke 8 and the second arc surface portion 9a of the second yoke 9 will be described. As shown in FIG. 4, at a phase angle of 0 degree, the opposed area of the pair of magnetized surfaces 3a and 3b of the magnet 3 with the first arc surface portion 8a and the second arc surface portion 9a is zero. When the phase angles in the plus (+) direction and the minus (−) direction are generated, the opposing areas are set to gradually increase in accordance with the increase amount.

  In the above configuration, when the engine is driven, the magnet 3 rotates in conjunction with the camshaft 2 and the first and second yokes 8 and 9 move around the outer periphery of the magnet 3 in conjunction with the crankshaft (not shown). The magnet 3 and the first and second yokes 8 and 9 rotate in the same direction. The magnetic flux corresponding to the facing area between the magnetized surface of the magnet 3 and the first and second yokes 8 and 9 is changed to the magnet 3, the first and second yokes 8 and 9, and the third and fourth yokes 10 and 10. 11 and a magnetic circuit composed of air gaps between them. The Hall element 14 outputs a voltage corresponding to the magnitude of the magnetic field between the third yoke 10 and the fourth yoke 11.

  Here, if the phase angle between the magnet 3 and the first and second yokes 8 and 9 is varied by driving a phase change actuator (not shown), the magnetized surfaces 3a and 3b of the magnet 3 and the first and first The facing area between the two yokes 8 and 9 is variable, and a magnetic flux corresponding to the variable facing area flows through the magnetic circuit. When the magnitude of the magnetic flux flowing through the magnetic circuit changes in this way, the magnetic flux density between the third yoke 10 and the fourth yoke 11 also changes accordingly, and the voltage value based on the changed magnetic field is changed to the Hall element 14. Is output (see FIG. 5).

  That is, when a rotational phase angle is formed between the magnet 3 interlocked with the rotation of the camshaft 2 and the first and second yokes 8 and 9 interlocked with the rotation of the crankshaft, both faces each other according to the rotational phase angle. The area changes, and a magnetic flux corresponding to the facing area constantly flows to the third and fourth yokes 10 and 11 through the first and second yokes 8 and 9 at all rotational positions. The Hall element 14 outputs a voltage value, and the Hall element 14 always detects the phase angle without depending on the rotation cycle of the camshaft 2 and the crankshaft. Therefore, phase angle information with high time resolution can be obtained even when the engine rotates at a low speed, so that precise valve timing control can be performed immediately after the engine is started.

  In the above embodiment, the magnetic detection means is the first yoke 8 and the second yoke 9 that are arranged to face the magnet 3 in the radial direction, and the magnetic transmission means is coaxial with the first yoke 8 and the second yoke 9. In addition, since the third yoke 10 and the fourth yoke 11 are provided with the hall element 14 interposed therebetween, the magnetic field lines at the position of the hall element 14 are stabilized by the third and fourth yokes 10 and 11. Therefore, very accurate phase angle information can be obtained.

  In the above embodiment, the first and second yokes 8 and 9 are arranged with a radial gap of a certain length L1 with respect to the magnet 3, so that the magnet 3, the first yoke 8 and the second yoke 9 are arranged. Since the air gap between the magnet 3 and the first yoke 8 and the air gap between the magnet 3 and the second yoke 9 do not change at all the rotational positions, and contributes to acquisition of stable phase angle information. .

  In the above embodiment, the third yoke 10 has an axial gap of a certain length L2 with respect to the first yoke 8, and the fourth yoke 11 has a radial length of a certain length L3 with respect to the second yoke 9. Since they are arranged with gaps, the gaps between the first yoke 8 and the third yoke 10 and the second yoke 9 and the second yoke 9 at all rotational positions of the first yoke 8 and the second yoke 9. Since the gap between the four yokes 11 does not change, it contributes to acquisition of stable phase angle information. As described above, in the above embodiment, since all the gaps do not change at all the rotational positions of the magnet 3 and the first and second yokes 8 and 9, all of the magnet 3 and the first and second yokes 8 and 9 can be used. Since the magnetic resistance of the magnetic circuit composed of the magnet 3, the first and second yokes 8 and 9, the third and fourth yokes 10 and 11, and the gaps therebetween is constant, Very stable phase angle information can be obtained.

  In the above embodiment, the first rotating body is the camshaft 2, the second rotating body is the crankshaft, and the rotational phase difference of the camshaft 2 with respect to the crankshaft is detected. Of course, the present invention can be similarly applied to a device for detecting the.

  In the above embodiment, since the magnetoelectric conversion means is constituted by the Hall element 14, it is possible to detect the phase angle with high accuracy at low cost. The magnetoelectric conversion element may be any element as long as it can detect the magnitude of the magnetic field and convert the magnitude of the magnetic field into an electric quantity, and may be composed of an element other than the Hall element 14. .

  The present invention can be embodied in another embodiment as follows. In the following other embodiments, the same operations and effects as those of the above embodiment can be obtained.

  (1) In the above embodiment, the magnetic transmission means is constituted by the third yoke 10 and the fourth yoke 11 arranged so as to sandwich the Hall element 14 therebetween. On the other hand, the magnetic transmission means may be constituted by only the fourth yoke 11, and the Hall element 14 may be arranged close to the first yoke 8. By adopting such a configuration, it is possible to obtain the effects of reducing the number of parts, simplifying the configuration, reducing costs, and the like.

  Further, technical ideas other than the claims that can be grasped from the above embodiment will be described together with the effects thereof.

  (A) In the phase angle detection device for a rotating body according to any one of claims 1 to 4, the first and second yokes are disposed with a constant radial gap with respect to the magnet. A device for detecting a phase angle of a rotating body.

  According to this configuration, the air gap between the magnet and the first yoke and the air gap between the magnet and the second yoke do not change at all rotational positions of the magnet and the first yoke and the second yoke. Contributes to acquisition of accurate phase angle information.

  (B) The rotating body phase angle detection device according to any one of claims 1 to 4 and (a), wherein the magnetoelectric conversion means is a Hall element.

  According to this configuration, a highly accurate phase angle can be detected at low cost.

1 is a cross-sectional view of a phase angle detection device according to an embodiment of the present invention. 1 is a perspective view of a main part of an embodiment of the present invention as viewed obliquely from below a phase angle detection device. FIG. 3 is a perspective view of the main part of the phase angle detection device according to the embodiment of the present invention as viewed from obliquely below. It is a figure which shows one Embodiment of this invention and shows the arrangement | positioning state of the magnet and the 1st and 2nd yoke in phase angle 0 degree. FIG. 3 is a diagram illustrating an output characteristic of a Hall element according to an embodiment of the present invention. It is a block diagram of the phase angle detection apparatus of a prior art example.

Explanation of symbols

1 Phase detection device 2 Camshaft (first rotating body)
3 Magnet 8 1st yoke (magnetic detection means)
9 Second yoke (magnetic detection means)
10 Third yoke (magnetic transmission means)
11 Fourth yoke (magnetic transmission means)
14 Hall element (magnetoelectric conversion means)
C center of rotation

Claims (4)

  A magnet that rotates in conjunction with the first rotating body, and a magnetic detection means that rotates in conjunction with the second rotating body on the same axis of the magnet, and whose opposing area changes according to the relative rotational position of the magnet. The magnetic transmission means is disposed opposite to the rotational position of the magnetic detection means in the same area and forms a magnetic path with the magnetic detection means, and the magnitude of the magnetic force lines passing through the magnetic transmission means is expressed as an electric quantity. And a magneto-electric conversion means for converting to a rotating body phase angle detection device.   The magnetic detection means is a first yoke and a second yoke that are arranged to face the magnet in the radial direction, and the magnetic transmission means is coaxial with the first yoke and the second yoke, and the magnetoelectric 2. The phase angle detection device for a rotating body according to claim 1, wherein the phase angle detection device is a third yoke and a fourth yoke provided with a conversion means interposed therebetween.   The third yoke has a fixed axial gap with respect to the first yoke, and the fourth yoke has a fixed radial gap with respect to the second yoke. The rotating body phase angle detection device according to claim 2, wherein the phase angle detection device is a rotating body. 2. The phase of the rotating body according to claim 1, wherein the first rotating body is a camshaft, and the second rotating body is a crankshaft, and a rotational phase difference of the camshaft with respect to the crankshaft is detected. Angle detection device.

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