JPS6020048Y2 - Electromagnetic signal detection device - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an electromagnetic signal detection device used to detect and control the state of a rotating body in, for example, an internal combustion engine.

Problems that the invention aims to solve Conventionally, as shown in Fig. 1, an electromagnetic signal detection device consists of a housing 1 fixed to an external device of a rotating body (for example, a cylinder block in the case of an internal combustion engine) with bolts, etc. The rotating shaft 3 is driven directly or indirectly by the rotating shaft (crankshaft in the case of an internal combustion engine) and rotates smoothly with respect to the housing 1 via a pole bearing 2, etc., and the housing 1 is connected to the housing 1 using screws 4, etc. It is composed of fixed signal generators 5A and 5B and a signal rotor 6 fixed to a rotating shaft 3.

As is well known, each of the signal generators 5A and 5B is composed of a fixed bracket 5a, a permanent magnet 5b, a pickup coil 5c, and an iron core 5d, and the signal rotor 6 is made of a magnetic material, and as the rotating shaft 3 rotates, The signal rotor 6 rotates, and a starting force is generated in the pickup coil 5c in response to changes in the magnetic flux penetrating the iron cores 5d of the signal generators 5A and 5B placed opposite the side surface 6a of the signal rotor 6, and this output voltage increases. is used as a signal to detect and control the state of the rotating body.

The number of signal rotors, the number of teeth of the signal rotor, and the number of signal generators that constitute an electromagnetic signal detection device vary depending on the type and control method of the rotating body whose state is to be detected and controlled. Here, as shown in Fig. 1, one signal rotor 6 having one tooth is used.
An example is given of an electromagnetic signal detection device composed of two signal generators 5A and 5B placed 1800 degrees opposite each other on the same plane with the signal rotor 6 in between.

Signal generator 5A of the electromagnetic signal detection device,
The output signal waveforms of 5B are shown in Figures 2a and 2b.

Here, the signal waveform indicated by symbol 7 is a signal that is originally output for use in detecting and controlling the state of the rotating body (for convenience, it is named 1 control signal y).
is output when it crosses the iron core 5d of each signal generator.

Therefore, this control signal 7 is transmitted to two signal generators 5.
Each of signals A and 5B is output once every rotation of the signal rotor 6, and their phases are 180° different from each other.

In addition, the signal waveform indicated by symbol 8 is a signal in which the control signal 7 output from the other opposing signal generator is superimposed with an opposite phase due to magnetic interference (named r magnetic interference signal y), and is the state of the rotating body. This is a completely unnecessary signal for detection and control.

Conventionally, as shown in Figure 3, a method for processing signals output from an electromagnetic signal detection device is to use a certain voltage level, that is, a threshold level.
For example, when the output signal voltage from the electromagnetic signal detection device is higher than the threshold level 9, the signal processing circuit performs processing by comparing 9 and the output signal voltage. A commonly used method is to create a pulse signal corresponding to the output signal of an electromagnetic signal detection device by setting the output of the circuit to 1' and conversely to 0° when the output is low.

In this case, as is generally known, the output signal voltage of the electromagnetic signal detection device is approximately proportional to the number of rotations of the signal rotor, so the output voltage also has a small value at low rotations.

Therefore, in order for the signal processing circuit to constantly detect the output signal of the electromagnetic signal detection device from low rotation to high rotation, it is necessary to set the threshold level 9 of the signal processing circuit to a low value.

At this time, if the magnetic interference signal 8 is superimposed on the output signal of the electromagnetic signal detection device as shown in Fig. 2, this magnetic interference signal 8 will also increase in proportion to the rotation speed of the signal rotor, similar to the control signal 7. Therefore, when the rotational speed exceeds a certain level, the magnetic interference signal 8 is detected by the signal processing circuit in the same way as the control signal 7, as shown in FIG. 3, and a pulse signal 8' is generated, causing problems in controlling the state of the rotating body. .

As mentioned before, both the control signal 7 and the magnetic interference signal 8 output from the electromagnetic signal detection device increase in proportion to the rotational speed of the signal rotor, so the above problem can be solved, that is, from low rotational speed. In order to always detect only the control signal 7 up to high rotation, for example, measure the time from when the control signal 7 is detected until the next control signal 7 is detected, or the peak voltage value of the control signal 7. What to do is to detect the rotation speed from this number and control the threshold level 9 of the signal processing circuit so that it is low at low rotation speeds and high at high rotation speeds, and also according to the rotation speed. Therefore, a method such as continuously changing the threshold level 9 must be used.

However, in order to use such a method, a circuit for detecting the rotation speed is first required, and at the same time, a signal processing circuit becomes complicated because the threshold level 9 is made variable, and it is necessary to control the threshold level 9. This has the disadvantage that a control circuit is required for the system, making the system more complex and large, and reducing reliability and cost performance.

The above has described the drawbacks of the conventional electromagnetic signal detection device consisting of one signal rotor and two signal generators as shown in Fig. 1. Similarly to the above, problems due to magnetic interference occur in an electromagnetic signal detection device that includes a signal generator that faces a signal rotor and generates an output signal.

In addition, regardless of the number of signal rotors and signal generators that make up the electromagnetic signal detection device, for example, even in an electromagnetic signal detection device that consists of one signal rotor and one signal generator, other electromagnetic devices on the output signal Magnetic interference signals induced from the magnetic field, noise signals caused by other radio waves, etc. may be superimposed, causing the same problems as described above.

In order to eliminate the above-mentioned drawbacks, the present invention devises the shape of the signal rotor so that a part of the output signal from the signal generator is biased to one side of the reference line, and prevents magnetic interference signals and other signals superimposed on that part. By reducing the apparent size of the noise signal, the S/N ratio of the output signal is improved, and even when noise such as magnetic interference signals is superimposed, malfunctions can be prevented in the entire rotation speed range by simply setting a certain threshold level. An electromagnetic signal that makes it possible to detect only the control signal, simplifying the subsequent signal processing circuit and control circuit, and improving the reliability and cost performance of the entire system that detects and controls the state of the rotating body. The object of the present invention is to provide a detection device.

Means for Solving the Problems In the present invention, a cylindrical ring-shaped signal rotor fixed to a rotating shaft and a plurality of signal generators facing the rotor are provided, and the cylindrical ring-shaped signal rotor is positioned at a reference position and at a reference position. It has a tooth-shaped protrusion, and it has a tooth-shaped protrusion, and
In the half circumference toward the 80° position, a large thickness is added to the 1
The other half of the circle returning from the 800° position to the reference position has a smaller thickness, and the 180° position rapidly goes from a larger thickness to a smaller thickness, thereby causing the signal generators to mutually magnetically An electromagnetic signal detection device is provided in which an interference signal is lowered in a polarity direction opposite to a threshold level of a waveform shaping circuit for a signal generator signal, so that a noise signal appears to be small.

Embodiment FIG. 4a is a sketch showing the signal rotor portion of the electromagnetic signal detection device provided in the present invention.

In FIG. 4a, 3 and 5d are a rotating shaft and an iron core, respectively, as shown in FIG. 1, and 10 is a signal rotor.

In the device of FIG. 4, two signal generators are provided facing each other at an angle of 180°.

Components other than the signal rotor 10 may be the same as those shown in FIG.

The signal rotor 10 is fixed to a rotating shaft 3, and as the rotating shaft 3 rotates, it rotates in the direction shown by the arrow in FIG. 4 in this example.

As in the case of Fig. 1, the two iron cores 5d are connected to the signal rotor 1.
They are placed 180 degrees opposite each other on the same plane with 0 in between.

FIG. 4 shows a plan view of this signal rotor 10.

The signal rotor 10 shown here has one tooth 10 for rotation.
d, and rotates in the direction of the arrow shown in the figure.

If the rotational angle position where the tooth 10d faces the iron core 5d is 00, the radius decreases as shown in the figure at the 180° position, and remains constant until the tooth 10d again faces the iron core 5d after one rotation. It has a shape with a radius of .

That is, the cylindrical ring-shaped signal rotor 10 has a toothed protrusion 10d at the 0° position, which is the reference position, and has a large thickness on the half circumference toward the 180° position from the reference position. The other half of the circumference returning from the position to the reference position has a small thickness, and at the 180° position there is a sudden change from a dog thickness to a small thickness.

In a specific example, the shape of the signal rotor 10 corresponds to the relative position of each signal generator, and the shape of the signal rotor 10 corresponds to the relative position of each signal generator, and the shape of the signal rotor 10 is adjusted according to the rotation of the signal rotor so that the noise signal is superimposed at the position of the largest signal in the opposite polarity direction to the threshold level. The signal generator is selected so that the facing distance from the tip of the iron core changes.

When such a signal rotor 10 is used, as the signal rotor 10 rotates, the distance from the tip 5e of the iron core 5d changes, and as shown in FIG. The amount of magnetic flux Φ decreases rapidly at the position .

As a result, the output signal waveform becomes as shown in Figure 4d.18
The output voltage drops to the negative side at the 0° position, and does not reach the threshold level 9 even if the magnetic interference signal 8 is superimposed.

That is, the magnetic interference signals between the signal generators are triggered in a direction opposite to the threshold level of the signal generator signal waveform shaping circuit, and the noise signal appears to be small.

Effects of the invention According to the invention, by designing the signal rotor that constitutes the electromagnetic signal detection device into an appropriate shape, a part of the output signal from the signal generator is shifted to one side of the reference line and superimposed there. It is possible to reduce the appearance of noise signals such as magnetic interference signals.

This improves the S/N ratio of the output signal, and even when noise such as magnetic interference signals is superimposed, only the control signal can be detected without malfunction in the entire rotation speed range by simply setting a certain threshold level. Is possible.

Therefore, there is no need to switch the threshold level based on the number of revolutions or to change it continuously according to the number of revolutions as in the conventional case.

Furthermore, since a rotational speed detection circuit and a threshold level control circuit are no longer required, and the signal processing circuit can be simplified, the entire system becomes simpler and reliability and cost performance are improved.

[Brief explanation of the drawing]

FIG. 1 shows the structure of a conventional device, in which a is a plan view and b is a longitudinal sectional view. FIGS. 2a and 2b are output signal waveform diagrams of a conventional device, and FIGS. 3a and 3b are waveform diagrams showing an output signal processing method of the conventional device. Figure 4 shows an embodiment of the present invention, in which a is a sketch showing the signal rotor portion, b is a plan view of the signal rotor, and C is a graph showing changes in the amount of magnetic flux Φ when the signal rotor rotates. , d are output signal waveform diagrams. 1; Housing, 2; Ball bearing, 3; Rotating shaft,
4; Bis, 5A, 5B; Signal generator, 5a;
Fixed bracket, 5b; Permanent magnet, 5C; Pick-up coil, 5d; Iron core, 5e; Tip of iron core, 6; Signal rotor, 6a; Teeth of signal rotor, 7; Control signal, 8; Magnetic interference signal, 7'; Pulse signal corresponding to the control signal, δ′; Pulse signal corresponding to the magnetic interference signal, 9;
Threshold level, 10; Signal rotor, 10d
; Signal rotor teeth.

Claims (1)

[Scope of utility model registration request] A cylindrical ring-shaped signal rotor fixed to a rotating shaft and a plurality of signal generators facing the rotor are provided, and the cylindrical ring-shaped signal rotor has a toothed protrusion at a reference position. It has a large thickness on the half circumference going from the 180° position to the reference position, a small thickness on the other half circumference returning from the 180° position to the reference position, and a large thickness at the 180° position. By suddenly changing the thickness from the top to the smallest, the magnetic interference signals between the signal generators are lowered in the direction opposite to the threshold level of the waveform shaping circuit of the signal generator signal, so that the noise signal appears to be underground. An electromagnetic signal detection device characterized by: