JP2724846B2 - Rotating body detection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting a rotating body, and more particularly, to detecting a rotation speed (speed) and a rotating (running) direction of a rotating body such as a wheel of an automobile. To a detection device.

(Technical background of the invention and its problems) The present applicant has previously proposed a travel guidance device (Japanese Patent Application
No. 62-306431). That is, the traveling guide device includes a rotation detecting means for detecting rotation of a wheel of the automobile. As this rotation detecting means, a magnetic sensor such as a Hall element can be used.

However, when a magnetic sensor is used, the detection signal level is very small, and if the noise component is weighed by the detection signal due to electromagnetic induction by an external noise magnetic field, it becomes difficult to determine the detection signal. There was a fear.

(Object of the Invention) It is an object of the present invention to provide a rotating body detection device capable of accurately detecting the number of rotations and the rotating direction of a rotating body.

(Summary of the Invention) A detection device according to the present invention is configured such that a magnet is attached to a rotating body so that N and S poles of the magnet are arranged along the rotating direction of the rotating body, and the rotation detecting coil is fixedly arranged. The first and second detection signals having different polarities are output in accordance with the magnetic poles of the magnet, and the amplitude level is controlled by the amplitude control means.
And supplying the second detection signal to the first and second voltage comparators in which reference voltages having different polarities are set, and each of the voltage comparators obtains a determination signal corresponding to each detection signal. And

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a detection device according to the present invention.
A magnet 2 is attached to the wheel 1 via an attachment (not shown). The magnet 2 is mounted such that the N pole and the S pole are along the rotation direction (the direction of the arrow). A rotation detecting coil 3 is arranged near the wheel 1 so as to face the magnet 2. The rotation detecting coil 3 is fixedly mounted on a chassis of an automobile or the like, and one end is grounded via the chassis or the like. Amplifiers 4 and 5 are connected in series to the other end of the rotation detection coil 3, and operational amplifiers 6 and 7 as voltage comparators are connected to the output side of the amplifier 5 at the subsequent stage. That is,
The output side of the amplifier 5 is connected to the non-inverting input terminal of one operational amplifier 6, and the constant voltage source 8 is connected to the inverting input terminal. The constant voltage source 8 is applied to the inverting input terminal of the voltages V ₁ as a reference voltage. The output side of the amplifier 5 is connected to the inverting input terminal of the other operational amplifier, and the negative side of the other constant voltage source 9 is connected to its non-inverting input terminal. The constant voltage source 9 is applied to the non-inverting input terminal of the voltage -V ₁ as a reference voltage. These operational amplifiers 6,
The output side of 7 is connected to the signal processing circuit 10. The signal processing circuit 10 includes a counter, a timer, and the like, each of which stores the determination pulses P ₁ , P ₂ output from the operational amplifiers 6, 7.

A variable attenuator 11 is provided between the amplifiers 4 and 5. The variable attenuator 11 is composed of an FET having a photocoupler configuration, and is controlled by a detector 12. That is, as the output of the detector 12 increases, the resistance value of the variable attenuator 11 also increases substantially in proportion thereto.

 Next, the operation of the detection device of the present invention will be described.

When the wheel 1 rotates in the direction of the arrow and the car starts moving forward, the S pole of the magnet 2 approaches the rotation detecting coil 3 first,
Then, when the S pole passes, the N pole approaches. Accordingly, the magnetic flux changes from S pole to N pole largely changes, the voltage on the rotation detecting coil 3 is induced, the voltage is output as the detection signals S ₁ of the positive electrode shown in FIG. 2 (A) You.

On the other hand, when the rotation speed of the wheel 1 increases, the change of the magnetic flux when switching from the S pole to the N pole increases, so that the detection signal S ₁ output from the rotation detection coil 3 is shown in FIG.
As shown in (2), the rising becomes steep and the voltage level also increases. That is, when the wheel 1 is changed to 0.15 rotations / sec to 30 rotations / sec, the voltage level of the detection signals S _1, for example changes from 2 _[m V] to 300 _[m V]. However, when the voltage level of the detection signal S ₁ is increased, so also increases the output level of the detector 12, the resistance value of the variable attenuator 11 increases. Therefore, always be detected signals S ₁ of a certain level is input to the amplifier 5 be large detection signals S ₁ voltage level than the rotation detecting coil 3 with increasing rotational speed of the wheel 1 is output.

The detection signal S ₁ amplified by the amplifier 5 is divided into operational amplifiers 6 and 7
Supplied to In this case the voltage level of the detection signals S ₁ of the positive electrode is greater than the reference voltage V ₁ of the operational amplifier 6, the detection signals S ₁ from the operational amplifier 6 is output as the result pulse P _1. In contrast, since the operational amplifier 7 is detected signals S ₁ of the positive electrode is input to the inverting input terminal, does not result pulse from the operational amplifier 7 is outputted. Therefore, when the determining pulse P ₁ from the operational amplifier 6 is output by detecting this in the signal processing circuit 10 side, it is possible to determine the direction of rotation of the wheel 1 as a positive direction. Thus, the vehicle is moving forward. Further, by calculating the number of outputs per determination pulse unit time P ₁ by the signal processing circuit 10, the rotational speed of the wheel 1, that is, it is possible to know the traveling speed of the vehicle.

Next, when the wheel 1 rotates in the direction opposite to the arrow and the vehicle starts to retreat, first the N pole of the magnet 2 approaches the rotation detecting coil 3 and then the S pole approaches. Therefore, from the rotation detecting coil 3 in this magnetic flux changes, as shown in FIG. 2 (B), the detection signal S ₂ of the negative electrode is output.

The detection signal S ₂ is set to a constant level in the variable attenuator 11 in the same manner, it is supplied to the operational amplifier 6 through the amplifier 5. In this case the detection signal S ₂ is a negative electrode, does not result pulse from operational amplifier 6 is output. In contrast, the detection signal S ₂ of the negative electrode to its inverting input terminal in the operational amplifier 7 is input, the determination pulse P ₂ is output. Therefore, by detecting the result pulse P ₂ by the signal processing circuit 10 side, it can be determined that the rotation direction of the wheel 1 are opposite. Therefore, the vehicle is retreating. Further, by calculating the number of outputs per much time determination pulse P ₂ by the signal processing circuit 10, it is possible to know the speed for retraction of an automobile.

 FIG. 3 shows another embodiment of the present invention.

In this embodiment, variable power supplies 8 ', 9' are connected to inverting input terminals and non-inverting input terminals of operational amplifiers 6, 7, respectively. The non-inverting input terminal of another operational amplifier 13 is connected to the output side of the detector 12. A constant voltage source 14 is connected to an inverting input terminal of the operational amplifier 13, and a reference voltage is applied. The output side of the operational amplifier 13 is connected to control terminals of the variable power supplies 8 'and 9'.

Note that the variable power supplies 8 'and 9'
A combination of an FET and a constant voltage source can be considered.

By the way, since a voltage is induced in the rotation detecting coil 3 due to the approaching and passing of one magnetic pole of the magnet 2 and the magnetized component of the wheel or the like, from the detecting coil 3, as shown in FIG. , the detection signal S ₁ superposed noise components S _n is output. Therefore, from the operational amplifier 6, as shown in FIG. 4 (b), determining the pulse P ₁ would be added unwanted noise pulse P _n on.

However, in the embodiment of FIG. 3, since the other operational amplifier 13 is connected to the detector 12, when the output level of the detector 12 becomes higher than the reference voltage of the constant voltage source 14, the control voltage V _s is outputted from the operational amplifier 13. Is output. The control voltage V _s is applied to the variable power supply 8. Therefore, the reference voltage applied to the inverting input terminal of the operational amplifier 6 is V ₁ , as shown in FIG.
Since it further changes (increases) to V ₂ , only the determination pulse P ′ ₁ shown in FIG. 5 is output from the operational amplifier 6. That is,
The noise pulse _Pn is removed.

Similarly, the detection signal S ₂ to the noise component of the negative electrode is applied to the control voltage V _s is the variable power supply 9 'be superimposed, the reference voltage of the operational amplifier 7 is changed to -V ₂ than -V ₁ (reduction) to because, only determining pulse P _'2 having no noise pulse P _n from the operational amplifier 7 is outputted.

Therefore, erroneous processing can be prevented from occurring on the signal processing circuit 10 side, so that the rotation speed and the rotation direction of the wheel 1 can be accurately detected.

FIG. 6 shows still another embodiment of the present invention.
In this embodiment, an amplifier 1 with a dead zone is provided before the operational amplifiers 6 and 7.
5 is arranged, and the other operational amplifier 1 is connected to the control terminal of the amplifier 15.
Output 3 is connected. Amplifier 15 with dead zone is + V _s
And −V _s are set, and 0 to + V _s
Output becomes "0" volts in the input voltage range and the input voltage in the range of 0 to-V _s, when there is a large input voltage of the absolute value than + V _s or -V _s, the voltage at A times the amplification degree Output.

In an embodiment of the FIG. 6, when the control signal of a predetermined level from the operational amplifier 13 in the augmentation of the detection signals S ₁ is output, while level voltage -V _s of the dead zone with amplifier 15 is lowered. Thus, the detection signals S ₁ and the other level voltage + V _s
For larger, but is amplified to A times the noise component S _n of the negative side is reduced or removed from the level voltage -V _s is pulled down. Therefore, it is possible to clearly distinguish the determination pulse P ₁ and a noise pulse P _n, the signal processing circuit
Malfunction of the 10 side can be prevented.

FIG. 7 shows another embodiment of the present invention. In this embodiment, a noise canceling coil 16 is connected to the rotation detecting coil 3 in series. These coils 3 and 16 are connected so that the polarities for generating an induced voltage are opposite to each other. The noise canceling coil 16 is arranged so as to be separated from the magnet 2 and at the same distance as the rotation detecting coil 3 with respect to a road surface or the like.

By the way, since a transformer is buried under a road or the like, an external noise magnetic field is generated.

Now, when the magnet 2 approaches the rotation detection coil 3 by the rotation of the wheel 1, as described above, the detection signal is output from the coil 3.
S ₁ and S ₂ are output. On the other hand, the noise canceling coil 16
Is separated from the magnet 2 and does not output a voltage.

On the other hand, when an external noise magnetic field is generated in a transformer or the like, a noise component is induced in the rotation detection coil 3, but a noise component is also induced in the noise operation coil 16. However, since these two coils 3 and 16 are connected to have opposite polarities, the noise component generated by the rotation detecting coil 3 and the noise component generated by the noise canceling coil 16 have opposite polarities, so that they are mutually canceled. Is done. Therefore, almost no noise component is output to the amplifier 4 side. As a result, the pulses P ₁ and P ₂ having no noise pulse _Pn are converted to the signal processing circuit 10.
Can be sent to

In the above embodiments, the present invention is applied to the detection of the number of rotations and the direction of rotation of the wheels of an automobile. However, it goes without saying that the present invention can be applied to other pairs of rotations.

(Effects of the Invention) As described above, according to the present invention, the rotation detection coil outputs the first and second detection signals having different polarities in accordance with the magnetic poles of the magnet, and amplifies these detection signals. Since the level is controlled and the first and second voltage comparators having reference voltages having different polarities are compared to obtain a determination signal corresponding to each detection signal, the rotation of the rotating body is controlled. The speed and the rotation direction can be reliably detected.

Also, since the reference voltages of the first and second voltage comparators are varied by the waveform shaping means, and the noise component induced by the rotation detecting coil is canceled by the noise canceling coil,
Furthermore, the rotation speed and the rotation direction of the rotating body can be reliably detected.

[Brief description of the drawings]

FIG. 1 is a block diagram of a detection device according to the present invention, and FIGS. 2A and 2B are waveform diagrams respectively showing detection signals of different polarities output from a rotation detection coil according to the present invention.
FIGS. 3 and 6 are block diagrams of a detection device according to another embodiment of the present invention, and FIGS. 4 (a) and 4 (b) show a detection signal containing a noise component and a determination pulse containing a noise pulse. FIG. 5 is a waveform diagram of a determination pulse obtained by the detection device shown in FIG. 3 and FIG. 6, and FIG. 7 is a part of a detection device showing still another embodiment of the present invention. FIG. 1 ... wheel, 2 ... magnet, 3 ... rotation detection coil, 4,5 ... amplifier, 6, 7, 13 ... operational amplifier, 8, 9, 14 ... constant voltage source, 10 ... signal processing circuit , 11: Variable attenuator, 15: Amplifier with dead band, 16: Noise canceling coil.

Claims (4)

(57) [Claims] 1. A device for detecting the number of rotations and the direction of rotation of a rotating body, the magnet being attached to the rotating body and having an N pole and an S pole arranged along the rotation direction. A rotation detection coil that is fixedly opposed to the magnet and outputs first and second detection signals having different polarities corresponding to the magnetic poles of the magnet; and the first and second detections output. Amplitude control means for controlling the amplitude level of the signal; reference voltages having different polarities are respectively set; the reference voltage is compared with the first and second detection signals whose amplitude levels are controlled; Output the first
And a second voltage comparator. 2. The apparatus according to claim 1, further comprising waveform shaping means for changing a reference voltage of said first and second voltage comparators when the amplitude levels of said first and second detection signals exceed a predetermined value. The rotating body detection device according to claim 1. 3. The amplifier according to claim 1, further comprising a dead band amplifier for amplifying the first detection signal at a point in time when one of the set levels is exceeded and for changing the other set level to the opposite polarity side. Rotating body detection device. 4. The detection of a rotating body according to claim 1, further comprising a noise canceling coil connected in series to said rotation detecting coil and canceling a noise component induced by said rotation detecting coil. apparatus.