JPS5814059A - Rotation signal generator - Google Patents

Abstract

PURPOSE:To achieve a high durability by arranging an U-shaped amorphous magnetic body forcibly bent in part facing a magnetic pole of a permanent magnetic rotor whose N pole and S pole are alternately formed in the circumferential direction and an electric coil wound thereon. CONSTITUTION:A ring-shaped permanent magnet 2 is fastened on a rotor 1 and magnetized with the side surface thereof circumferentially polarized into 12 poles N-S-N-S... The rotor 1 is supported with bearings 41 and 42 separately forced into casings 31 and 32. In the embodyment thereof used for a wheel velocity sensor, one end 1a of the rotor 1 is connected to a power shaft of a transmission while the other end 1b thereof to a speed meter cable and a U-shaped amorphous magnetic body 5 forcibly bent is arranged near the side surface of the permanent magnet 2. The amorphous magnetic body 5 was previously coated with a flexible insulation resin when it was flat and a coil 6 is wound thereon somewhat coarsely.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a signal generator that generates an electrical signal in response to the rotation of a permanent magnet rotor.

This type of signal generator includes an on-off type that uses the magnetic force of a permanent magnet to close a reed switch, and a type that uses a pickup coil to induce a voltage according to changes in magnetic force. Those using reed switches have a problem with the durability of the reed contacts, and those using pickup coils have a problem of low responsiveness in the low speed range because the induced voltage is low when the rotation speed of the permanent magnet rotor is low.

The first object of the present invention is to provide a permanent magnet rotor type rotation signal generator that is highly durable and has high responsiveness in the low speed range, and has easy pulse processing and accurate rotation even in the low speed range. A second object is to provide a rotation signal generator that can obtain pulses synchronized with the rotation signal generator.

In order to achieve the above object, in the present invention, in a pickup coil type rotational signal generator, the core of the pickup coil is made of an amorphous magnetic material that is forced to bend.

According to this, a compressive force acts on the surface on the bending side of the amorphous magnetic material, and a tensile force acts on the surface on the elongated side, so that the magnetization retention force is different on both sides, and the Leigand effect appears. In other words, in response to changes in the magnetic field applied to the core due to the rotation of the permanent magnet rotor, the timing of the direction change of the core magnetic flux is different between the bending side and the extension side, and when the direction of the magnetic flux changes in one layer, there is a sharp rise and fall. A pulsed voltage is induced in the electrical coil. The peak value of this pulse voltage is almost unaffected by the rotational speed of the rotor, and the frequency of the pulse voltage is completely synchronized with changes in the external magnetic field, ie, with the rotation of the permanent magnet rotor. Therefore, a constant level synchronization pulse can be obtained even in a low speed range. In addition, amorphous magnetic materials must be made by rapidly cooling liquid metal, so they are thin plates, and magnetically they are ferromagnetic, with high permeability and saturation magnetization, low coercive force, and mechanically Extremely high breaking strength, excellent elasticity and restorability. Since such amorphous magnetic material is thin, it is easily saturated by the rotor's magnetic flux, and the electric coil wound around it has a wire that responds to the rotation of the rotor.
Easily generates voltage pulses due to the Gantt effect. Mechanically, it is easy to manufacture and has high vibration and impact resistance and repeatability.

FIG. 1a shows an embodiment of the invention. In FIG. 1a, a ring-shaped permanent magnet is fixed to a rotor 1. In FIG.

The side peripheral surface of the permanent magnet 2 is N −8−N −8− in the circumferential direction.
--- It is polarized and magnetized into 12 poles (6 S poles, 6 N poles). The rotor 1 is fitted with bearings 4. which are press-fitted into the casings 3I and 32, respectively. and 4□. Since this embodiment is used as a vehicle speed sensor, the rotor 1
One end 1a is connected to the output shaft of the transmission, and the other end 1b is connected to the speedometer cable. An amorphous magnetic body 5 forced into a U-shape is arranged near the side peripheral surface of the permanent magnet 2.

FIG. 1b shows a longitudinal section of the amorphous magnetic material 5 (IB-IB in FIG. 1a), and FIG. 1C shows a plane of the end of the amorphous magnetic material 5. When the amorphous magnetic material 5 is flat (straight), it is coated with a flexible insulating resin, and after an electric coil 6 is wound somewhat roughly on it, a flexible insulating resin is further coated on the amorphous magnetic material 5. The amorphous magnetic material 5 that is coated and integrated with the electric coil 6 in this way is
Slit 9 in forced frame 8. , 9□ through both ends and forced to bend into a U-shape. The forced frame 8 is fixed to the support stand 1o. Slit 9. , 92 is set equal to the distance between N-8 adjacent poles of the permanent magnet 2 in the circumferential direction. By making them equal in this way, the strength of the magnetic field applied between the tips of the amorphous magnetic body 5 becomes high, and the fluctuation of the magnetic field according to the rotation of the rotor 1 becomes large.

As shown in FIG. 2a, the amorphous magnetic material 5 is forced to bend in a U-shape, and a compressive force C is applied to the surface (inner surface) on the bent side.
However, a tensile force T is always acting on the stretch side surface (outer surface). As a result, the magnetic properties are such that the saturation magnetic flux density is small and the coercive force is small on the bent side surface where the compressive force C is applied, as shown by the dashed-dotted line BHC in Figure 2b, and the magnetic property is shown by the dashed-double line BHT. As shown, on the extension side surface where the tensile force T is applied, the saturation magnetic flux density is equal to 1, and the holding force is equal to 0. The solid line shows the magnetic properties of the interface where neither tensile nor compressive forces are acting.

As a result, when the rotor 1 rotates and the magnetic field of the permanent magnet 2 that affects the amorphous magnetic material 5 changes in a sine wave shape as shown in FIG. The direction of the magnetic flux instantaneously reverses in this plane, and a sharp pulse voltage is induced in the coil 6 (Leigand effect).

The reversal speed of magnetic flux in this amorphous magnetic material is
This pulse voltage peak is a constant value that can be considered to be substantially unrelated to the rotational speed of the rotor 1 because it is extremely faster than the rate of increase/decrease in the magnetic flux due to the rotation of the rotor 1. However, there is a one-to-one correspondence between the rotational speed of the permanent magnet 2 and the vibration of the magnetic field applied to the amorphous magnetic body 5, and a sharp voltage □ pulse is induced only at a specific phase of the vibration of the magnetic field. The frequency of the pulse is proportional to the rotation speed of the rotor 1,
This proportional relationship exists even in the low speed range.

Therefore, the pulse induced in the electric coil 6 can be used as a timing pulse, it can be amplified, the pulse or amplified pulse can be used to trigger a mono-multi-bi-break to widen the pulse width, or the pulse sound can be counted to determine the speed. Desired processing can be performed using conventionally known signal processing, such as detecting or integrating a wide-width processed pulse to obtain a speed indicating analog voltage.

In any case, the voltage pulse induced in the electric coil 6 is sharp, its level does not substantially depend on the rotational speed of the rotor 1, and its frequency is proportional to the rotational speed of the rotor 1. Therefore, there is an advantage that rotational synchronization is accurate in the low speed range and speed detection is accurate. In addition, there are no electrical contacts and the structure is mechanically simple.
Extremely durable.

[Brief explanation of the drawing]

FIG. 1a is a longitudinal sectional view of one embodiment of the present invention, FIG. 1b is an enlarged sectional view taken along the line IB-IB, and FIG. 1C is an enlarged plan view of the end of the amorphous magnetic material 5. FIG. 2a is an enlarged perspective view of the amorphous magnetic material 5, FIG. 2b is a graph showing the magnetization characteristics of the magnetic material 5, and FIG. 2C is a time chart showing the correlation between the magnetic field applied to the magnetic material 5 and the voltage induced in the coil 6. It is a chart.

Claims (2)

[Claims] (1) Permanent magnet rotor with N and S poles alternately formed in the circumferential direction, an amorphous magnetic material that is forced to bend into a U shape or an arc shape with a portion facing the magnetic poles of the permanent magnet rotor, and an amorphous magnetic material. Rotary signal generator with a wound electric coil. (2) The distance between the ends of the amorphous magnetic material is 5
The rotation signal generator according to claim 1, wherein the tip of the end portion is opposed to the magnetic pole of the permanent magnet rotor so as to correspond to the distance between the north pole and the south pole.