JPS5822684B2 - Rotation angle detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a crankshaft rotation angle and rotation speed detection device for a rotating body such as an engine in an automobile or the like.

Optical and electromagnetic systems have been proposed as rotation angle and rotation speed detection devices for rotating bodies in automobiles, and recently magnetic sensors using semiconductor elements such as Hall elements and magnetoresistive elements have been proposed. Applications can also be seen.

However, the optical type has problems with reliability due to vibrations, dust, etc., the electromagnetic type has output voltage changes depending on the rotation speed, and the type using semiconductor elements has poor temperature characteristics (and shock resistance). Weak, expensive, etc.
Each has its own drawbacks when used in automobiles.

Therefore, the present applicant has improved the above-mentioned drawbacks of the conventional technology, and has many features such as excellent temperature characteristics and impact resistance, extremely simple structure, low cost manufacturing, and not being affected by external magnetic fields. Japanese Patent Application No. 50-40984 proposed a rotational angle and rotational speed detecting device which has a rotational angle and a rotational speed and can obtain a constant level of output voltage regardless of the rotational speed of a rotating body.

The characteristics of this technology are as follows.

``A magnetic detection device that consists of two magnetic detection elements each made of a thin film magnetic wire with uniaxial anisotropy and an induction coil placed inside a magnetic shield case via a magnetic shield plate, and is fixed to a non-rotating part. It has a head, a multi-polar magnetized magnetic disk that is integrally attached and fixed to a rotating body, and a non-magnetic disk that has small magnets suitably formed on its outer periphery, and the outer periphery of the double-ended plate is connected to the magnetic detection device. Disposed close to the head, the small magnet and one magnetic detection head detect the reference position of the rotating body, and the multipolar magnetized disk and the other magnetic detection head detect the rotation angle and rotation speed of the rotating body. ``A device for detecting the rotation angle and rotation speed of a rotating body, which is characterized by the following.''

However, in the above technology, since the multipolar magnetized disk rotates and the magnetic detection head is fixed to a non-rotating part, it is inevitable that the multipolar magnetized disk and the magnetic detection head The structure is exposed to the outside.

Therefore, if the magnetic disk is dropped on the ground or the magnetic detection head collides with another object during the manufacturing or repair process, the device itself will be damaged.

Generally, in manufacturing or repair sites, people are not accustomed to handling precision equipment, so the frequency of damage to the equipment is quite high.

Therefore, the present invention aims to improve the above-mentioned drawbacks of the prior art, and its object is to provide a rotation angle detection device that is easy to handle and difficult to damage.

A feature of the present invention for achieving this purpose is that a magnetic detection head is attached to a rotating shaft, and a magnet cylinder with multi-pole magnetization on the inner surface is installed in a non-rotating manner that covers the magnetic detection head and is concentric with the rotating shaft. This is due to the fact that it is fixed in the section.

Embodiments of the present invention will be explained in detail with reference to the drawings. FIG. 1 is a configuration and connection diagram of a magnetic detection head 1 of the apparatus of the present invention.

The operating principle of this type of magnetic detection head was developed by the present inventors, and in connection with this, a patent application was filed in 1983-3.
No. 7590 (Japanese Unexamined Patent Publication No. 48-3377) and many other patent and utility model registration applications have been filed.

The detection head having the above structure has a coil attached to the magnetic wire, which has uniaxial magnetic anisotropy with the axis of hard magnetization in the axial direction and the axis of easy magnetization in the circumferential direction. When a magnetic field is applied from the outside, the presence of a magnetic field is detected by the voltage induced in the coil.

In FIG. 1, a core conductor 7 made of phosphor bronze or the like is plated with a permalloy thin film 8 with a thickness of about 1 μm, a coil 6 is applied around it, a capacitor 9 is connected in parallel with it, and the permalloy thin film is further in contact with the permalloy thin film 8. A ferrite yoke 3 having a central gap 4 and having both ends sandwiching the coil.
The magnetic detection head 1 is configured by the above.

When an alternating current is applied to the core wire conductor 7 by the input power source 10, the coil 6 is activated only when an external magnetic field is applied to the permalloy thin film 8 through the ferrite yoke 3 in the axial direction of the core wire, that is, in the direction of the hard magnetization axis. output terminal (OUT)
In this case, an output voltage having a frequency twice that of the voltage of the human power source 10 is obtained.

A capacitor 9 connected in parallel with the coil 6 is used to form a resonant circuit with the coil.

FIG. 2 is a sectional view perpendicular to the rotation axis of the rotation angle detection device according to the present invention, FIG. 3 is a perspective view of the rotation angle detection device according to the present invention, and FIG. 4 shows the rotation axis of the rotation angle detection device according to the present invention. debt(
FIG.

In each figure, reference number 1 is a magnetic detection head, and 11 is a magnet cylinder that is fixed to a non-rotating part and receives the magnetic detection head 1 inside, and its inner surface is multipole magnetized as shown in Figure 2. .

12 is a rotating shaft, 13 is a head holder for fixing the magnetic detection head to the rotating shaft, 14 is a rotary transformer, 14a is a rotor of the rotary transformer, 14b is a stator of the rotary transformer, 15 is a link between the magnetic detecting head and the rotary transformer. Wiring that electrically connects the rotor,
16 is an output line from the stator of the rotary transformer.

In FIGS. 2, 3, and 4, AC signals from an AC power source 10 are applied to the magnetic detection head 1 via a rotary transformer 14. In FIGS.

When the rotating shaft 12 rotates, the magnetic detection head 1 rotates, and as the rotating shaft 12 rotates, the magnetic cylinder 11
detects the magnetic pole magnetized on the inner surface of the

When a magnetic pole is detected, the magnetic detection head turns on the AC power supply 100.
It outputs a frequency twice the frequency, and the output is taken out to the outside via the rotary transformer 14.

No output is generated when the magnetic detection head does not detect a magnetic pole.

The rotary transformer is used to prevent the wiring from the magnetic detection head from being twisted due to rotation and to connect the head to an external circuit in a non-contact manner, and its structure itself is well known and will not be described in detail.

Regarding the operation of the present invention, the magnetic detection head 1 rotates as the rotating shaft rotates 120 times, and as the rotating shaft rotates, the magnetic detection head 1 detects the magnetic field from the magnetic pole on the inner surface of the magnet cylinder.

Since the magnetic poles are arranged at predetermined positions on the inner surface of the magnet cylinder, by analyzing the magnetic field detected by the magnetic detection head 1, the relative position of the magnetic detection head 1 with respect to the magnetic poles, that is, the rotation angle of the rotation axis can be determined. In the present invention, the magnetic detection head 1 is located inside the magnet cylinder, so the device as a whole is mechanically strong (and the shielding effect of the magnet cylinder can be expected, so the device can be used in the manufacture of automobiles, etc.). It can be used under harsh conditions such as on-site or repair sites.

Furthermore, we created two sets of magnetic detection heads and magnet cylinders, and made the spacing between the magnetic poles of one of the magnet cylinders coarser.
By keeping the magnetic poles of the other magnet cylinder closely spaced, coarse and fine rotation angle detection can be performed at the same time.

The rough detection of the rotation angle can be used to count the number of rotations or to detect the reference position of rotation.

As explained above, in the rotation angle detection device according to the present invention, the magnetic detection head is mechanically and electrically shielded,
Since all the outer surfaces of the device are non-rotating parts, the magnet cylinder itself, its magnetized portion, and the magnetic detection head will not be damaged by external forces.

This effect can be further improved by covering the magnetic cylinder with a protective cover.

By applying the device according to the invention to detecting the crank angle of an internal combustion engine, precise and reliable control of the internal combustion engine becomes possible.

[Brief explanation of the drawing]

FIG. 1 is an electrical connection diagram of a magnetic detection head according to the present invention, FIG. 2 is a sectional view perpendicular to the axis of the rotation angle detection device according to the present invention, and FIG. 3 is a perspective view of the rotation angle detection device according to the present invention. 4
The figure is a sectional view parallel to the axis of the rotation angle detection device according to the present invention. 1; Magnetic detection head, 3; Yoke, 4; Gap, 6;
Coil, 7; Core wire conductor, 8; Permalloy thin film, 9; Capacitor, 10; AC power supply, 11; Magnet cylinder,
12; Rotating shaft, 13; Head holder, 14; Rotary transformer, 14a; Rotor, 14b; Stator, 15
, 16i wiring.

Claims (1)

[Scope of Claims] 1. A magnetic detection head having a structure in which an induction coil is provided on a thin film magnetic wire having uniaxial anisotropy, a rotating shaft to which the magnetic detection head is fixed, and a rotating shaft surrounding the magnetic detection head and the rotating shaft. a magnet cylinder that is fixed to a non-rotating part concentrically with the shaft and whose inner surface is magnetized with multiple poles, a rotary transformer whose rotor rotates together with the rotating shaft and whose stator is fixed, an output line of the magnetic detection head, and the rotary transformer. and wiring that electrically connects the lawn winding of the transformer, and detects the rotation angle of the rotary shaft or A rotation angle detection device characterized by detecting the number of rotations. 2. The rotation angle detection device according to claim 1, wherein two sets of a magnetic detection head, a magnet cylinder, and a rotary transformer are provided for a single rotating shaft, and the spacing between the magnetic poles of the two magnet cylinders is different from each other.