JPH07280507A - Rotation sensor - Google Patents

Abstract

PURPOSE:To enlarge output voltage and easily identify an output signal for noise by making the iron core of an electromagnetic pickup a bent shape according to the set position of the projection for the rotation angle detection of a signal rotor for the purpose of forming a closed magnetic circuit in the case where either end part of an iron core is opposed to a projection for arbitrary rotation angle detection. CONSTITUTION:A rotation sensor is provided with a signal rotor 2 wherein a plurality of projections for rotation angle detection 22 are separated and formed on a cylinder inner circumferential face 21a up to a specified angle and which is attached to either end part of a rotation shaft, and an electromagnetic pickup which is disposed on the inside of an inscribed circle of the projections for the rotation angle detection 22 of the signal rotor 2 in a non-contact state. In addition, the rotation sensor is provided with an iron core 31 which is positioned on the either end part 31. which forms and bends at an angle, integral multiple of a specified angle at the time when the end part 31. is opposed to arbitrary one of the projections for the rotation angle detection 22 and wherein the other end part 31b is opposed to the other projections for the rotation angle detection 22, a coil 32 wound around the iron core 31, and a magnet 33 32 for generating a line of magnetic force penetrating the coil 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation sensor which is attached to a rotary shaft such as a cam shaft and outputs an electric signal relating to the rotating state of the rotary shaft.

[0002]

2. Description of the Related Art Recently, gasoline engine ignition devices that do not use a distributor for distributing a high voltage to a spark plug have become popular. In such an ignition device, a cam position sensor that outputs a cylinder discrimination signal, a crank angle reference position signal, and an engine speed signal for determining ignition timing is used. In such a cam position sensor, an electromagnetic type is generally used. In the electromagnetic cam position sensor, timing rotors for respective signals are connected to a cam shaft, and the timing rotors and predetermined timing rotors are connected to each other. It is configured to obtain the signal from a pickup arranged with a gap. As a configuration similar to the electromagnetic type, a sensor coil is arranged inside a sleeve body made of a ferromagnetic material attached to the end of a rotary shaft, as in a measuring device for measuring a rotation angle disclosed in Japanese Patent Laid-Open No. 3-12501. It is also known to have a configuration.

In the electromagnetic cam position sensor described above, which is attached to, for example, a four-cylinder engine, the iron core around which the pickup coil is wound has a rotation angle of 90 ° formed on the inner surface of the timing rotor. The ends are opposed to the protrusions for detection, and a voltage is generated in the pickup coil every time the protrusions of the timing rotor pass through one end. When one end of the iron core faces an arbitrary protrusion, the other end of the iron core faces a protrusion 180 degrees apart from the protrusion, and a closed magnetic circuit is formed by the iron core and the timing rotor, which is generated in the pickup coil. This will increase the induced magnetism and increase the sensor output voltage.

[0004]

By the way, the above-mentioned 4
The structure of the pickup in the cam position sensor for a cylinder engine is generally the same even if the number of cylinders changes. That is, in a structure including an iron core whose ends are separated by 180 ° and a pickup coil wound near one end, in an engine with an even number of cylinders, as described above, The one end and the other end of the pickup and the two protrusions are aligned to increase the induced magnetism.

However, in a three-cylinder engine, the protrusions are formed every 120 °, and even if one end faces one of the three protrusions, the other end has another protrusion. It is not the one that opposes. This also applies to the opposite case, with the other end facing the protrusion and the other end not facing the other protrusion. Therefore, as shown in FIG. 6, when the sensor output voltage does not increase and the other end faces the protrusion, a useless voltage that does not become the above-mentioned signal is induced, and a normal output voltage is not obtained. It becomes a noise and reduces the noise resistance performance.

An object of the present invention is to eliminate such a problem.

[0007]

The present invention takes the following means in order to achieve such an object. That is, the rotation sensor according to the present invention includes a signal rotor having a plurality of rotation angle detection protrusions formed on the inner peripheral surface of the cylinder at a predetermined distance from each other and attached to one end of the rotation shaft, and a rotation angle of the signal rotor. And an electromagnetic pickup arranged in a non-contact state inside an inscribed circle of the detection projection, wherein the one end of the electromagnetic pickup is opposed to any one of the rotation angle detection projections. An iron core positioned on an extension line of one end portion that bends to form an angle that is an integral multiple of a predetermined angle, and the other end portion faces another rotation angle detection protrusion, and a coil wound around the iron core And a magnet that generates a magnetic force line penetrating the coil.

[0008]

With this structure, the iron core of the electromagnetic pickup is bent at an angle that is a positive multiple of a predetermined angle without the ends of the iron core being aligned. Therefore, when the signal rotor rotates and one end of the signal rotor faces the rotation angle detecting protrusion, the other end faces the other rotation angle detecting protrusion. That is, each end of the iron core faces a separate rotation angle detecting protrusion,
A closed magnetic circuit is formed by the iron core and the signal rotor. As a result, the lines of magnetic force generated from the magnet pass through the iron core, reach the rotation angle detection protrusion from one end, pass through the signal rotor, and then rotate again from the other rotation angle detection protrusion to the iron core. Penetrate inside. Therefore, the induced magnetism induced in the coil is increased, the output voltage of the electromagnetic pickup is increased, and the SN ratio can be increased.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The cam rotation sensor 100 shown in FIG. 1 is applied to a three-cylinder engine 1 for an automobile, and a plurality of rotation angle detection projections 22 are formed on the inner peripheral surface 21a of the cylinder body 21 at a predetermined angle α.
A signal rotor 2 attached to one end of an intake valve drive cam shaft 11 which will be described later and is a separated rotary shaft, and a rotation angle detecting projection 22 of the signal rotor 2 is not in contact with the inside of the inscribed circle. Electromagnetic pickup 3 placed
It has and. Cam rotation sensor 1 in this embodiment
00 outputs, for example, a cylinder discrimination signal and a crank angle reference position signal necessary for an ignition system without a distributor. Also, this cam rotation sensor 10
The engine 1 to which 0 is attached is of a three-cylinder double overhead camshaft (DOHC) type, and utilizes a space portion at one end of the intake valve drive camshaft 11 in which a sprocket for driving the camshaft is housed. It can be attached by. Specifically, in this DOHC engine, a sprocket is fixed to one end of an exhaust valve driving camshaft, and the sprocket is driven by a chain stretched between the sprocket and the crankshaft.

The intake valve drive camshaft 11 and the exhaust valve drive camshaft are constructed so as to rotate in opposite directions by a gear installed in a space near the sprocket chamber 13 of the cylinder head 12.
A bearing portion 14 formed on the upper portion of 2 rotatably supports the bearing. A camshaft bearing cap 14a is attached to the bearing portion 14 to form a camshaft shaft support hole 14b. The inner peripheral surface of the cam shaft support hole 14b is a sensor mounting formed by a cap 17 and a mounting portion 16 provided on the side wall 15 of the cylinder head 12 for mounting the electromagnetic pickup 3 of the cam rotation sensor 100, which is a rotation sensor. Hole 1
It is processed coaxially with 8. Therefore, the cam shaft support hole 14
b and the sensor mounting hole 18 which is an opening for mounting the electromagnetic pickup 3 are formed coaxially.
The mounting portion 16 uses a semicircular cutout that is necessary when processing the bearing portion 14 of the intake valve drive camshaft 11, and faces the end portion of the intake valve drive camshaft 11. It is provided on the side surface 15 of the cylinder head 12, which is the outer side surface of the sprocket chamber 13. Therefore, it is provided on the side wall 15 facing one end of the intake valve drive camshaft 11 to which the signal rotor 1 is attached.

The signal rotor 2 is axially provided on the inner peripheral surface of a cylindrical tubular body 21 with a boss in accordance with the number of cylinders of the engine 100, at a predetermined angle α in the circumferential direction of the tubular body 21. A protrusion 22 for detecting the rotation angle is formed and is attached to one end of the intake valve drive camshaft 11. In this embodiment, three rotation angle detection projections 22 are provided for each 120 ° in accordance with the number of cylinders, and a projection 23 for a crank angle reference signal is further provided.
The signal rotor 2 having such a shape is attached to one end of the intake valve drive cam shaft 11 and is arranged in a dead space in the sprocket chamber 13 of the cylinder head 12 that is a position facing the shaft drive sprocket. Will be installed. Therefore, its outer diameter is
It does not have to be a particularly severe restriction as long as it can be accommodated in the dead space. Also, the cylindrical body 2
The size of a circle inscribed inside the tip of the rotation angle detecting projection 22 inside 1, i.e., the substantial inner diameter is the outer diameter of the electromagnetic pickup 3 plus a radial clearance. The shape of the inside of the cylindrical body 21 excluding the rotation angle detection protrusion 22 is not particularly specified, but may be formed so that the electromagnetic pickup 3 outputs the maximum electric signal at the position of the rotation angle detection protrusion 22. .

The electromagnetic pickup 3 has one end portion 31a which is bent when one end portion faces any one of the rotation angle detecting projections 22 and forms an angle which is an integral multiple of the predetermined angle α.
An iron core 31 located on the extension line of the other end 31b facing the other rotation angle detecting projection 22, a coil 32 wound around the iron core 31, and a magnetic field line penetrating the coil 32 is generated. And a magnet 33. The electromagnetic pickup 3 according to this embodiment has, for example, an iron core 31 with a magnet 33 around which a coil 32 is wound inside a case 34 formed of a synthetic resin cylinder that transmits magnetic force lines. The output voltage can be taken out from the flange 34a provided on the.

The iron core 31 has 12 ends in advance.
It is formed by laminating ferrite thin plates formed so as to form an angle of 0 ° and in a bent position, and one end portion 31a thereof is formed to have substantially the same width as the rotation angle detection protrusion 22. The other end 31b is formed to be wide in accordance with the size of the magnet 33. When the electromagnetic pickup 3 is housed in the signal rotor 2, one end 31
One of the gap between the a and the rotation angle detecting protrusion 22 is the case 3
4 is set to a distance slightly larger than the sum of the thickness of the cylinder and the clearance between the case 34 and the rotation angle detecting projection 22, and the other gap with the other end 31b is about 1 to Set about 4 times. This other gap is
If the dimension is larger than the above value, it is difficult to form a closed magnetic circuit, which is not preferable.

The coil 32 has one end 31 of the iron core 31.
It is wound on the a side via a bobbin, and the magnet 33 is attached to the lower side thereof. The coil 32 and the magnet 33 may be attached to the iron core 31 in the same structure as the conventional one.

An O-ring seal 5 is mounted on the outer peripheral surface of the case 34 for the purpose of maintaining the sealing property of the mounting portion and preventing the inclination of the axis line during fine adjustment of the mounting of the electromagnetic pickup 3. Two grooves 34b are formed so as to be separated from each other in the axial direction. As shown in the figure, the electromagnetic pickup 3 has a flange 34a on the side wall 15 of the cylinder head 12.
It is fixed by a single bolt 6 inserted into a mounting adjustment hole formed at the lower end side of the, and the bolt 6 can be loosened for fine adjustment.

In the above structure, the sensor mounting hole 18 and the cam shaft support hole 14b are machined coaxially, and when the intake valve drive cam shaft 2 is assembled, the cam rotation sensor 10 is installed.
Assembly of 0 is carried out. First, the signal rotor 2 is attached to one end of the intake valve drive camshaft 11.
The intake valve drive camshaft 11 to which the signal rotor 2 is attached is placed on the bearing portion 14 of the cylinder head 12, and the camshaft bearing cap 14a is fixed to each bearing portion 14 to fix the cylinder head. 12 is rotatably attached. When the signal rotor 2 is attached, since the output voltage output from the electromagnetic pickup 3 differs depending on the rotation angle detection protrusion 22, the reference rotation position of the intake valve drive camshaft 11 and the reference rotation angle detection protrusion 22. Align and press accurately and press. Next, the cap 13 is fixed to the mounting portion 16 of the cylinder head 12, and the sensor mounting hole 18 is formed.
Before mounting the electromagnetic pickup 3 in the sensor mounting hole 18, the O-ring seal 5 is mounted in the groove 34b of the case 34, and is mounted in the sensor mounting hole 18 with the mounting adjustment hole of the flange 34a facing downward. Then, the bolt 6 is inserted into the attachment adjustment hole 41d and temporarily fixed.

After the assembly of the cam rotation sensor 100 is completed in this way, when the engine is assembled and operated, the electromagnetic pickup 3 is placed on either the left or right side while observing the output voltage output from the electromagnetic pickup 3. The rotation angle detection projection 22 of the signal rotor 2 is rotated in the direction of the
The timing of facing the one end 31a of the No. 1 is adjusted. In this case, when one end 31a of the iron core 31 faces the rotation angle detecting protrusion 22, the other end 31b also faces the other rotation angle detecting protrusion 22. Therefore, the magnet 3
The magnetic lines of force generated from 3 penetrate the portion of the iron core 31 around which the coil 32 is wound, enter the signal rotor 2 from one end 31a through the gap, and from the other rotation angle detecting protrusion 22 to the other. It enters the inside of the iron core 31 again through the end portion 31b to form one closed magnetic circuit. In this way, the closed magnetic circuit M
By forming C, the induced magnetism that penetrates through the iron core 31 is increased, the induced electromotive force induced in the coil 32 is increased, and the output voltage is increased. Therefore, the SN ratio, which is the ratio of the output voltage to the noise, is improved, and the cylinder-specific signal and the crank angle reference signal can be easily recognized.

The cam rotation sensor 100 of this embodiment is used.
Does not have a case of itself, and is formed by attaching the signal rotor 2 to the intake valve drive camshaft 11 and attaching the electromagnetic pickup 3 to the side wall 15 of the cylinder head 12. 100
It becomes a state that it is stored in the cylinder head 12,
In other words, the flange 34a portion of the electromagnetic pickup 3 is left and the other portion is accommodated in the dead space portion of the sprocket chamber 13 of the cylinder head 12, so that it is possible to suppress an increase in the size of the entire engine and to reduce the number of parts. Since it can be reduced, the cost can be easily reduced. Since the electromagnetic pickup 3 is formed in the side wall 15 of the cylinder head 12 and is attached to the sensor mounting hole 18 which is machined coaxially with the cam shaft support hole 14b of the intake valve drive cam shaft 11, the electromagnetic pickup 3 and the electromagnetic It is possible to minimize the misalignment of the axis with the pickup 3, and it is possible to maintain the relative angle between the iron core 31 of the electromagnetic pickup 3 and the rotation angle detection projection 22 of the signal rotor 2 at a right angle with high accuracy. Therefore, the radial clearance in the cam rotation sensor 100 can be reduced, and the output voltage generated by magnetism can be increased.

Since the electromagnetic pickup 3 is attached via the two O-ring seals 5,
When the mounting angle of the intake valve drive camshaft 11 relative to the reference position in the circumferential direction is variably adjusted, the electromagnetic pickup 3 can be prevented from being tilted off the axis by the clearance of the sensor mounting hole 18, and the crank can be prevented. The phase shift of the intake valve drive camshaft 11 with respect to the axis and the phase shift of the signal rotor 2 having the rotation angle detection protrusion 22 with respect to the intake valve drive camshaft 11 can be easily corrected. Furthermore, the outer diameter of the signal rotor 2 can be increased according to the size of the dead space,
Since the electromagnetic pickup 3 can be made larger according to the size of the signal rotor 2, it is possible to increase the output voltage generated in proportion to the changing speed of magnetism.
Therefore, the rotation detection accuracy can be improved.

The present invention is not limited to the embodiment described above. For example, the cam rotation sensor 100 applied to the three-cylinder engine has been described in the above embodiment, but as another embodiment, the signal rotor 2 of the signal rotor 2 as shown in FIG. The rotation angle detecting projections 22 are provided in the circumferential direction at intervals of 72 °, and the iron core 31 is formed in a shape bent at an angle of, for example, 144 ° correspondingly. The iron core 31 is
When one of the ends 31a faces one arbitrary rotation angle detecting protrusion 22, the other end 31b may face the other rotation angle detecting protrusion 22, so that, for example, the bending angle can be changed. It may be 72 ° (shown by an imaginary line in the figure), but in this case, some twisting is required in the winding method.

Further, in the above embodiment, an example in which the entire case of the cam rotation sensor itself is not provided has been described, but the configuration is such that the signal rotor and the electromagnetic pickup are housed in one case. Good. In this case, the rotary shaft may be projected from the rear surface of the cylindrical body forming the signal rotor to the outside of the case so that the rotary shaft can be connected to the target rotary shaft such as the cam shaft.

Further, in the above embodiment, the gear drive system 3 is used.
I explained the cylinder DOHC engine, but the DOH of the system that drives each camshaft only by the timing belt.
It may be a C engine or a SOHC engine. Then, in such an engine, the signal rotor 2 may be attached to the other end portion different from the end portion to which the drive sprocket fixed to the end portion of the camshaft is fixed. It is preferable that the signal rotor 2 is integrally formed on the side surface of the drive sprocket that faces the side wall of the cylinder head 12. By constructing the sprocket and the signal rotor 2 in one body, the same effect as in the above embodiment can be obtained, and since the signal rotor 2 is integrated with the driving sprocket 8, the number of parts is further reduced. Since the number of assembling steps can be reduced accordingly, the cost can be further reduced.

Besides, the configuration of each part is not limited to the illustrated example, and various modifications can be made without departing from the spirit of the present invention.

[0024]

As described above in detail, the present invention has the iron core 31 of the electromagnetic pickup having the bent shape satisfying the predetermined condition set according to the installation position of the rotation angle detecting projection of the signal rotor. By doing so, a closed magnetic circuit is formed when one end of the iron core faces an arbitrary rotation angle detection protrusion, so that the output voltage can be increased and the output signal can be recognized against noise. Can be made easier.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view showing an essential part of an engine in which an embodiment of the present invention is assembled.

FIG. 2 is an exploded perspective view showing the same embodiment.

FIG. 3 is an end view taken along the line AA of FIG.

FIG. 4 is a waveform chart showing a change in output voltage according to the first embodiment.

FIG. 5 is a view corresponding to FIG. 3 of another embodiment of the present invention.

FIG. 6 is a waveform diagram showing changes in the output voltage of the conventional example.

[Explanation of symbols]

 2 ... Signal rotor 3 ... Electromagnetic pickup 11 ... Intake valve drive camshaft 11a ... One end 21 ... Cylindrical body 21a ... Inner peripheral surface 22 ... Rotation angle detection protrusion 31 ... Iron core 31a ... One end 31b ... Another End 32 ... Coil 33 ... Magnet α ... Predetermined angle

Claims (1)

[Claims] 1. A signal rotor having a plurality of rotation angle detection protrusions formed on a circumferential surface of a cylinder body at a predetermined distance from each other and attached to one end of a rotation shaft, and a rotation angle detection protrusion of the signal rotor. And an electromagnetic pickup arranged in a non-contact state inside the tangent circle, wherein the electromagnetic pickup is an integral multiple of the predetermined angle when one end faces any one of the rotation angle detecting projections. An iron core that is positioned on the extension line of one end that forms an angle and bends, and the other end faces the other rotation angle detection protrusion,
A rotation sensor comprising: a coil wound around the iron core; and a magnet that generates a magnetic force line penetrating the coil.