JP2001255172A - Power generation type electromagnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a power generation type electromagnetic sensor, which can exhibit superior effects of detection with high reliability without decreasing an output voltage, in a low-speed rotation region and without outputting an abnormal high voltage in a high-speed rotation region in a module of various gears. SOLUTION: In this power generation type electromagnetic sensor, a capacitor 6 and a resistor 7 in Fig.1 are connected as a frequency characteristics control impedance in the inside. Moreover, an insulation fluid is impregnated or filled in a power generation coil part. Output energy from the power generation coil is converted from a voltage form into current form, so that the problem resulting from the high voltage output is solved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly reliable power generation type electromagnetic sensor for electrically detecting a rotation speed and the like.

[0002]

2. Description of the Related Art Generally, in a power generation type electromagnetic sensor,
The output voltage of the generator coil was directly led to the output terminal.

In general, a power generation type electromagnetic sensor obtains a power generation output by a temporal change in magnetic flux due to a projection of a rotating body such as a gear, so that when the rotation speed becomes slow, the output voltage falls and a wide speed detection range can be obtained. Because of the difficulty, a design policy has been adopted in which the output voltage is slightly increased to obtain a high output voltage even in a low-speed region.

[0004]

In a real use site,
Although there are various types of gear modules, it is difficult to obtain a large output voltage with a small module gear, but a very large output voltage is obtained with a large module gear or a derivative having a large change in magnetic flux. If the gap between the tooth tip and the detection end of the power generation type electromagnetic sensor is narrow, the output voltage increases substantially in inverse proportion to the square of the distance.

[0005] In the field, there is a case where the detection performance from a low speed is required so much that it is necessary to operate even in a high speed rotation region. Power generation type electromagnetic sensors designed with the hope of a large output voltage may cause a failure, and depending on the operating conditions, the output voltage may exceed several hundred volts to exceed 1,000 volts. Depending on the impedance connected as the load of the power generation type electromagnetic sensor, the energy of a large electromotive force is consumed by the internal resistance of the power generation coil, so that the power generation coil self-heats and the temperature rises, resulting in the reliability being impaired. .

Further, when the load resistance is high and the generated energy is largely output in the form of a voltage, such a high output voltage causes a layer short-circuit of the generating coil and also causes the generation coil to cover the magnet wire. Even under such high-voltage conditions, even a slight scratch causes electrolytic corrosion to progress in a short time due to the action of the surrounding electrolytic substance, causing a disconnection accident. An object of the present invention is to provide a concept of a power generation type electromagnetic sensor corresponding to such a use condition.

[0007]

According to the present invention, the output voltage is not hindered in the low-speed region due to the high-output physical conditions in order to maintain the reliability even under the above-mentioned use conditions, but the high-speed region is not affected. Under the operating conditions of a large module, it is possible to detect a wide speed range with high reliability without outputting a high voltage which can be said to be proportional to the abnormality.

In general, a power generating coil is wound with a large number of ultrafine magnet wires in order to obtain a high output voltage in a low-speed region, so that its internal impedance is large, and the output voltage is greatly influenced by the load conditions of the coil. .
From this fact, according to the present invention, as a load of the power generation coil of the power generation type electromagnetic sensor, in addition to the load connected to the outside, an appropriate load impedance is connected inside the power generation type electromagnetic sensor to output the output energy of the power generation coil from the voltage form to the current. In this case, the problem caused by the high voltage output is solved to improve the reliability.

In this case, the generated energy flows back inside the power generation coil in the form of electric current, so that the temperature of the power generation coil rises. For this reason, in the present invention, the coil portion is impregnated or filled with an insulating fluid to radiate heat from the coil.

According to the present invention, in order to optimize the output voltage obtained at the output terminal 5 of FIG.
And the resistor 7 and impregnating or filling the power generating coil portion with an insulating fluid to obtain a constant such that the adjusting effect is not exerted in the low-speed region. The present invention provides a concept of increasing the load to lower the voltage and dissipating Joule heat due to the current flowing back inside the power generation coil at the time, and the present invention relates to a power generation type electromagnetic sensor based on such a concept. is there.

According to the above means, the output voltage of the power generating coil is generated by the electromotive force due to the temporal change of the magnetic flux crossing the coil. Therefore, when the gear is rotating at high speed, the teeth of the magnetic gear are moved closer or farther away. The frequency at which the magnetic field fluctuates increases, and if one focuses on one tooth, the temporal magnetic flux change is large, and the electromotive force increases. On the other hand, when the module is a large gear, even if the frequency is the same as that of the small gear, the size of the peaks and valleys of the teeth is large. The change width of the resistance increases. For this reason, the change in the magnetic flux crossing the power generation coil of the power generation type electromagnetic sensor increases even if the frequency is the same, so that the electromotive force also increases.

This means that the change in magnetic flux per unit time is large, and the reactance of the added capacitor 6 in FIG. 1 becomes small. It becomes a current flowing through the capacitor 6, and consequently, the energy of the electromotive force has changed from a voltage form to a current form.
Therefore, even in the measurement under the condition where the rotation speed changes over a wide range, and also under each condition from a small module to a large module as a detection gear, the output generated due to the excessive electromotive force is high voltage. It is possible to solve the problem of reliability deterioration due to a failure.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram showing the principle of a power generation type electromagnetic sensor according to the present invention, and FIG. 2 is a graph showing an operation state thereof.

Next, the operation of the embodiment will be described with reference to the drawings.

In FIG. 1, when a power generation type electromagnetic sensor for detecting the rotation of the rotating gear 4 is placed facing the tooth tip 8, a power generation coil 1 is mounted on the pole piece 2 of the power generation type electromagnetic sensor. It is assumed that the magnet 3 is disposed behind the wound pole piece 2. When the gear 4 rotates in this state, the tip 8 and the valley of the tooth alternately appear, so that the gap between the tip 8 of the gear and the pole piece becomes wider or narrower. It changes every time the first eight passes. At this time, since the pole piece 2 is excited from behind by the magnet 3, the magnetic flux in the pole piece 2 changes every time the tooth tip 8 passes, and an electromotive force is generated in the power generation coil in proportion to the frequency of the magnetic flux change. This electromotive force is proportional to the frequency as shown at 23 in FIG. 2, but the graph becomes more curved as the frequency becomes higher due to the influence of the internal impedance of the coil, the eddy current of the pole piece, and the stray capacitance. However, this curve cannot be expected to be as effective as satisfying the requirements to be solved by the present invention.

Therefore, in the present invention, a capacitor as shown in FIG. Since the reactance of the capacitor 6 is inversely proportional to the frequency, the output voltage generated by the connection of the capacitor becomes almost short-circuited by the capacitor when the frequency increases, so that almost no output voltage appears.

In this case, the resistor cannot be used in a high frequency region. Therefore, a resistor as shown in FIG. Since this resistor is independent of frequency, the harm that the output voltage is hardly produced by the capacitor 6 is mitigated, and as a result, the output voltage is generated when the output voltage decreases with the capacitor 6 as the frequency increases. The phenomenon that the electromotive force increases with the frequency is canceled, and a substantially flat output characteristic is obtained.

This state is as shown in FIG.
It shows almost flat characteristics with respect to frequency. The reason why the curve tends to decrease in the high frequency region as in the case of the characteristic 23 is the same as in the case of the characteristic 23, that is, the impedance of the power generation coil 1 increases with the frequency, and the eddy current of the pole piece increases. Also, it is difficult to take out the electromotive force due to the influence of the floating capacity floating on the coil and the like.

Thus, the resistor 7 is connected in series with the capacitor 6.
Even if the frequency increases, the resistance value that is not related to the frequency can maintain a constant impedance even if the reactance of the capacitor approaches zero, so that an appropriate output voltage is applied to the output terminal 5 in a high frequency region. Can be obtained.

The power generation type electromagnetic sensor according to the present invention is not limited to the illustrated example described above, but may be variously modified without departing from the gist of the present invention.

[0022]

As described above, the first aspect of the present invention is as described above.
According to the power generation type electromagnetic sensor described in (1) to (4), in various gear modules, an excellent reliability is obtained in that the output voltage is not reduced in the low-speed rotation range and the abnormal high voltage is not output in the high-speed rotation range. The effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing the principle of a power generation type electromagnetic sensor.

FIG. 2 is a graph showing an operation state thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Generating coil 2 Pole piece 3 Magnet 4 Gear 5 Output terminal 6 Capacitor 7 Resistor 8 Gear tip 23 Electromotive force voltage characteristic of generating coil 24 Output voltage characteristic of power generation type electromagnetic sensor of the present invention

Claims (2)

[Claims] 1. A power generation type electromagnetic sensor in which a reactance is connected to an output circuit and a frequency characteristic of an output voltage according to a power generation frequency is adjusted. 2. A power generation type electromagnetic sensor in which an insulating fluid is filled around a power generation coil.