JPS626537Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a non-contact type rotation speed detector, and in particular, the present invention is directed to a multi-pole magnetized ring-shaped This relates to something that makes it possible to match the level of alternating magnetic flux density by rotating a magnet.

[Conventional technology and problems]

In the conventional rotational speed detector of this type, as shown in Figs. 1 and 2, a rotating body 2 made of a non-magnetic material is fixed to a rotating shaft 1, and a ring-shaped magnet 3 with multiple magnetized poles is embedded in one side of the rotating body 2.
A cylindrical block 4 made of synthetic resin is disposed at a position facing the ring-shaped magnet, and a magnetoelectric conversion element 5 such as a Hall IC is fixed to the ring-shaped magnet side of the cylindrical block 4.
Here, the relationship between the output voltage of the magnetoelectric conversion element 5 and the detected magnetic flux density generally has a hysteresis characteristic as shown in Fig. 3A. The alternating magnetic flux density caused by the rotation of the multi-pole magnetized ring-shaped magnet 3 shown in B is detected, and a rectangular pulse shown in C is obtained as an output to determine the number of rotations and the rotation speed.

Incidentally, many of the magnetoelectric conversion elements 5 have different switching operating points in terms of magnetic flux density due to variations among individual products. Therefore, conventionally, products that match the level of alternating magnetic flux density due to the rotation of the multi-pole magnetized ring-shaped magnet 3 are selected and combined in response to individual variations in the magnetoelectric conversion elements 5, but this reduces the man-hours of product selection. was increasing, leading to a rise in prices. In addition, in order to match the switching operating point of each magnetoelectric transducer 5, the magnetoelectric transducer 5, the multi-pole magnetized ring magnet 3, and the gap L must be finely adjusted, and this adjustment requires very advanced technology. I needed it.

As for this type of non-contact type rotation speed detector, there is a prior art, for example, in Japanese Utility Model Application Publication No. 54-88428, in which a magnet is attached to the magneto-electric transducer on the fixed side, and the rotating body is magnetically attached. Although the structure is such that an inductor that constitutes the circuit is provided, even in this case, the switching operating point of the magnetoelectric transducer and the magnetic flux density of the magnet are fixed, so the above-mentioned problems occur.

In view of these circumstances, the present invention makes it possible to adjust the magnetic flux density of the magnetic field that a multi-pole magnetized ring-shaped magnet exerts on the magneto-electric transducer. An object of the present invention is to provide a rotation speed detector that eliminates the need for gap adjustment between the rotation speed and the rotation speed.

[Means for solving problems]

For this purpose, the rotation speed detector according to the present invention is
By movably adding a unipolar magnet to the side opposite to the multipolar magnetized ring-shaped magnet of the magneto-electric conversion element and adjusting the magnetic field exerted on the magneto-electric conversion element of the ring-shaped magnet,
The present invention is characterized in that the waveform of the alternating magnetic flux density of the ring-shaped magnet can be made to match the variation in the characteristics of the magnetoelectric conversion element.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to the drawings. In Fig. 4, a rotating shaft 1, a non-magnetic rotating body 2, a multi-pole magnetized ring-shaped magnet 3, a non-magnetic cylindrical block 4, and a magneto-electric conversion element 5 are configured in the same manner as in Figs. 1 and 2, and a monopole magnet 6 is installed on the back side of the magneto-electric conversion element 5 in the cylindrical block 4, i.e., on the opposite side to the ring-shaped magnet 3. The monopole magnet 6 is screwed into the cylindrical block 4 by a screw 7 so that the magnetic flux density of the magnetic field exerted from the ring-shaped magnet 3 on the magneto-electric conversion element 5 can be adjusted.
The distance M between the magnetoelectric conversion element 5 and the magnet is variable, and a groove 8 is provided at the end of the monopole magnet 6 for inserting a tool during adjustment.
is formed.

Furthermore, as shown in FIG. 5, when the magnetoelectric transducer 5 performs switching operation in the N-pole field with respect to the multi-pole magnetized ring-shaped magnet 3, the S pole of the unipolar magnet 6 is opposed to the magnetoelectric transducer 5. The amount of magnetic flux density detected is increased to make it appear as if the waveform level of the alternating magnetic flux density of the multi-pole magnetized ring-shaped magnet 3 has increased. Therefore, when the magnetoelectric conversion element 5 performs a switching operation in the S magnetic field, the N poles of the unipolar magnets 6 are arranged to face each other.

With this configuration, the magnetic flux density detected by the magnetoelectric conversion element 5 is determined by the magnetic flux density By of the magnetic field produced by the multi-pole magnetized ring magnet 3 and the magnetic flux density By of the magnetic field produced by the multi-pole magnetized ring magnet 3.
The magnetic flux density of the magnetic field due to the single-pole magnet 6 becomes Bx.
Generally, the magnetic flux density is a vector quantity, and the definition of addition holds true, so the magnetic flux density Bz detected by the magnetoelectric conversion element 5 is Bz=Bx+By. Here, the magnetic flux density By is a function of the rotation angle θ of the multi-pole magnetized ring-shaped magnet 3, and is therefore an alternating magnetic flux density waveform generated by its rotation.
On the other hand, the magnetic flux density Bx can be arbitrarily set by varying the distance M between the magnetoelectric conversion element 5 and the unipolar magnet 6. Therefore, the magnetoelectric conversion element 5
The detected magnetic flux density is obtained by increasing the level of the waveform of the alternating magnetic flux density of the ring-shaped magnet 3 by the magnetic flux density corresponding to the distance between the magnetoelectric conversion element 5 and the unipolar magnet 6.

Therefore, if the characteristics of the switching operation of the magnetoelectric conversion element 5 are low as shown in FIG. It is not necessary to move the unipolar magnet 6 away and thereby adjust the magnetic flux density. However, if the characteristics of the magnetoelectric conversion element 5 are such that the switching operation point is high as in (b), the switching operation will not occur if the alternating magnetic flux density of the ring-shaped magnet 3 is at a low level as in (c) above. Therefore, the distance M between the unipolar magnet 6 and the magnetoelectric transducer 5 is shortened, the amount of magnetic flux density detected by the magnetoelectric transducer 5 is relatively increased, and the waveform of the alternating magnetic flux density is at the same level as the characteristic in (b). By pulling it up to the position, it becomes possible to match and perform a switch operation.

[Effect of idea]

As is clear from the above description, according to the present invention, it is possible to match the alternating magnetic flux density of the multipolar magnetized ring-shaped magnet 3 by adjusting the magnetic flux density detected by the magnetoelectric conversion element 5. Therefore, even if there are variations in the characteristics of the magnetoelectric transducer 5, there is no need for product sorting and assembly man-hours can be reduced, and there is no need to adjust the gap between the magnetoelectric transducer 5 and the ring-shaped magnet 3, making installation easy. become. A unipolar magnet 6 is movably provided on the back side of the magnetoelectric conversion element 5, and the magnetic flux density is adjusted using the magnetic field of the ring-shaped magnet 3, so the structure is simple and the operation is reliable.

[Brief explanation of the drawing]

Figure 1 is a side sectional view of a conventional rotation speed detector;
The figure is a plan view of the same detector, A in Figure 3 is a hysteresis characteristic diagram of the magnetoelectric conversion element, B is an alternating magnetic flux density waveform diagram due to rotation of multipolar magnetization, and C is an alternating magnetic flux density of B in magnetoelectric conversion element A. Rectangular pulse diagram when detecting
FIG. 4 is a side sectional view of the embodiment of the present invention, and FIG. 5 is a diagram showing the magnetic flux density distribution between the magnets of the embodiment of the present invention.
Figure 6 is an illustration of the adjustment of the alternating magnetic flux density waveform of the multipolar magnet due to variations in the magnetoelectric transducer, where A and B are the magnetoelectric transducer elements, and C is the alternating magnetic flux of the multipolar magnet when the magnetoelectric transducer is in the normal setting positional relationship. Density waveform diagram D is a waveform diagram when the alternating magnetic flux density waveform of a multipolar magnet is moved using the action according to the present invention. DESCRIPTION OF SYMBOLS 1... Rotating shaft, 2... Rotating body, 3... Ring magnet, 4... Cylindrical block, 5... Magnetoelectric conversion element, 6... Unipolar magnet, 7... Screw, 8... Groove.

Claims (1)

[Scope of utility model registration request] A multi-pole magnetized ring-shaped magnet is attached to a non-magnetic rotating body fixed to a rotating shaft, and a magneto-electric conversion element is placed close to and facing the fixed side of the ring-shaped magnet, with the magneto-electric conversion element being sandwiched between the rings. A rotation speed detector comprising a unipolar magnet on the opposite side of the shaped magnet, and a distance from the magnetoelectric conversion element to the magnetoelectric conversion element can be adjusted.