JPH05180852A - Rolling bearing speed detector - Google Patents

Abstract

PURPOSE:To provide a stable comparison of signals regardless of the variation of output voltage in a device of generating a pulse signal after comparing the output voltage of a coil with a preset voltage by winding the coil on either magnetic material which is fitted on the track wheel of a bearing. CONSTITUTION:A pulsar ring 4 and a magnetic sensor 8 are fitted to the outer wheel 3 and the inner wheel 2 of a bearing 1, respectively, and a high frequency voltage generator 13 is connected to a coil 10 which is wound on the sensor 8. A rectification smoothing circuit 15 is connected to the coil 10 and connected to the set value input terminal of a comparison circuit 18 via a low-path filter 19. A signal that the output voltage of the coil smoothed is compared with a low frequency signal that the smoothed signal is filtered to generate a pulse signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation speed detecting device for a rolling bearing which supports wheels and a steering shaft of an automobile.

[0002]

2. Description of the Related Art In an automobile equipped with an anti-skid brake system, a rotation speed is detected from a bearing that supports wheels. Conventionally, as a rotation detecting device for such a bearing, the present applicant has previously filed Japanese Patent Application No. 3-24.
It was proposed by No. 7766.

In the proposed device, as shown in FIG. 4, a pulsar ring 33 having a large number of teeth 35 and 36 on the peripheral surfaces of a bearing ring 31 on the rotating side and a bearing ring 32 on the stationary side, respectively.
The detection ring 34 is attached, and the high frequency voltage adding means 37 is connected to the coil L wound around the detection ring 34. In this structure, when the coil L is excited by a high frequency voltage of frequency f ₀ , a magnetic circuit is formed between the pulser ring 33 and the detection ring 34, and when the pulser ring 33 rotates in that state, the magnetic resistance changes, The coil inductance changes. The output voltage of this coil is
The carrier component of f ₀ is removed through the rectifying and smoothing circuit 38,
By comparing the signal with the set value m in the comparison circuit 39, a pulse signal corresponding to the rotation of the bearing is obtained.

[0004]

In the device proposed above,
The set value to be compared with the smoothed voltage signal in the comparison circuit 18 is a fixed value m. However, in reality, the output voltage of the coil L may change due to an assembly error of each circuit, a temperature change during use, or the like. The amplitude and average value of the smoothed voltage signal may fluctuate significantly.

In this case, if the smoothed voltage signal with respect to the fixed set value m does not change across the set value m, a pulse signal associated with the rotation cannot be obtained and the rotation cannot be detected.

Therefore, an object of the present invention is to provide a rotation speed detecting device capable of stably and reliably detecting rotation regardless of fluctuations in the output voltage of the coil.

[0007]

In order to solve the above-mentioned problems, the present invention has a magnetic material ring having a large number of teeth arranged at equal pitches on the peripheral surface of a rolling bearing ring of a rolling bearing. A magnetic material around which a coil is wound is attached to the orbital ring so as to face the teeth of the ring, and a high-frequency voltage adding means and a rectifying / smoothing circuit for removing a carrier component from the output voltage of the coil are provided on the coil. In a rolling bearing rotation speed detection device connected to a comparison circuit that compares the signal to a set value, the output of the rectifying and smoothing circuit is input to the set value input terminal of the comparison circuit via a low-pass filter with a break frequency of several Hz or less. The structure is such that the terminals are connected.

[0008]

In the above structure, the signal smoothed by the rectifying and smoothing circuit and the signal of only the low frequency component are input to the comparison circuit by the filtering of the low pass filter, and the pulse signal is generated by comparing the two signals. ..

The low-frequency signal filtered by the low-pass filter fluctuates according to the fluctuation of the output voltage of the coil.
The smoothed signal always has an averaged value, and the pulse signal can be reliably generated.

[0010]

1 to 3 show a rotation speed detecting device according to an embodiment. The rolling bearing 1 shown in FIG. 1 is used by fixing the inner ring 2 and rotating the outer ring 3, and a pulsar ring 4 is attached to the inner diameter surface of the outer ring 3 on the rotating side.
The pulsar ring 4 is formed by laminating a plurality of silicon steel plates, and a large number of teeth 5 are formed on the inner peripheral surface of the entire peripheral surface at equal pitches.

On the other hand, an annular metal holding frame 6 having a U-shaped cross section is press-fitted to the outer diameter surface of the inner ring 2 on the fixed side, and the resin layer 7 is press-molded inside the holding frame 6. ,
A sensor 8 made of a magnetic material such as soft ferrite is incorporated.

The sensor 8 has projections 9 and 9 formed on both ends thereof so as to face the teeth 5 of the pulser ring 4, and a coil 10 is wound between the projections 9 and 9. Also,
The protrusions 9 and 9 engage with the recesses 11 and 11 provided in the holding frame 6 and face the teeth 5 of the pulsar ring 4 with a gap.

The coil 10 wound around the sensor 8 is
As shown in FIG. 1 (b), the capacitor 12 is
Are connected in parallel to form an LC resonance circuit, and the high frequency voltage generator 13 and the voltage detection means 14 are connected to the resonance circuit.

The high frequency voltage generator 13 has a frequency of 1
It oscillates a high-frequency voltage of 0 KHz, and the coil 10 is excited by applying a high-frequency voltage that vibrates to the coil 10.

On the other hand, the voltage detecting means 14 includes a rectifying circuit 16
And a rectifying / smoothing circuit 15 including a smoothing circuit 17 for removing a carrier wave component, and a comparing circuit 18. The smoothing circuit 17 is directly connected to one input terminal of the comparing circuit 18 and the other terminal is A low pass filter 19 connected to the smoothing circuit 17 is connected. The low-pass filter 19 uses a filter having a break frequency of several Hz or less, and outputs a signal of a lower frequency from the signal smoothed by the smoothing circuit 17 to the comparison circuit 18.

In the structure of the voltage detecting means 14, the output voltage of the resonance circuit composed of the coil 10 and the capacitor 12 is
The smoothed signal is rectified and smoothed in the rectifying / smoothing circuit 15, and the smoothed signal is input from one terminal of the comparison circuit 18, while the low-frequency signal passing through the low-pass filter 19 is input from the other terminal of the comparison circuit 18. It In the comparison circuit 18, the smoothed signal and the low frequency signal are compared,
A pulse signal corresponding to the frequency of the smoothed signal is output.

The voltage detecting means 14 and the high frequency voltage generator 13 are incorporated in a power source and an output connector, and a coaxial cable 20 is connected between them and the coil 10.

At the end of the outer ring 3 of the rolling bearing 1,
A seal member 21 is attached, and this seal member 2
The elastic seal 22 of No. 1 is in sliding contact with the end surface of the holding frame 6 to prevent infiltration of muddy water or dust into the bearing.

This embodiment has the structure as described above, and its operation will be described below. When the coil 10 is excited with a high frequency voltage by the high frequency voltage generator 13, the soft ferrite sensor 8 is magnetized, and a magnetic circuit is formed between the sensor 8 and the pulser ring 4.

In this state, when the rolling bearing 1 rotates and the pulser ring 4 and the sensor 8 rotate relative to each other, the magnetic resistance of the magnetic circuit changes periodically and the inductance of the coil 10 also changes periodically.

In this case, since the coil 10 and the capacitor 12 connected in parallel form an LC resonance circuit, the coil 1
When 0 is excited at a constant frequency f ₀ , the inductance of the coil 10 changes and the amplitude of the resonance circuit changes. When the output voltage is rectified / smoothed by the voltage detecting means 14, the carrier component f ₀ is removed, and FIG.
A smoothed signal B corresponding to the change in the inductance as shown in (a) is obtained.

Next, the smoothed signal B is input from one terminal of the comparison circuit 18 while the low-pass filter 19 is supplied.
At, the high frequency component is filtered, and the low frequency signal B as shown in FIG. 3B is input from the other terminal. When the output voltage of the resonance circuit fluctuates, the low-frequency signal (b) fluctuates together with the smoothed signal, and thus is always a signal close to the average value of the smoothed signal. Therefore, when the smoothing signal B and the low frequency signal B are compared in the comparison circuit 18, they are both shown in FIG.
As shown in FIG. 7, the pulse signal is always crossed, and the pulse signal accompanying the rotation of the pulser ring 4 can be obtained at the crossing point.

In the above embodiment, the detection structure in which the sensor 8 is opposed to the pulsar ring 4 is shown. However, in the detection device shown in FIGS. 4 (a) and 4 (b), the rectifying / smoothing circuit 38 and the comparison circuit. Even if the setting input terminal 39 is connected via the low-pass filter 19, the same operation as described above can be obtained.

The present invention can be similarly applied to the case of rotating the inner ring of the rolling bearing.

[0025]

As described above, according to the present invention, after the output voltage of the coil is rectified and smoothed, the smoothed signal is compared with the signal obtained by passing the smoothed signal through the filter to generate the pulse signal. Even if the signal of the output voltage fluctuates, the signals can be surely compared with each other, and stable and highly accurate rotation detection can be performed.

[Brief description of drawings]

FIG. 1A is a sectional view showing an embodiment, and FIG. 1B is a block diagram showing a voltage detection structure of the same.

FIG. 2 is a cross-sectional view showing a mounting portion of a pulser ring and a sensor according to an embodiment.

3A is a waveform diagram of a smoothed signal, FIG. 3B is a waveform diagram of a low-frequency signal, and FIG. 3C is a waveform diagram of superimposed signals.

FIG. 4A is a sectional view showing a conventional example, and FIG. 4B is a block diagram showing a voltage detection structure of the same.

[Explanation of symbols]

 1 rolling bearing 2 inner ring 3 outer ring 4 pulser ring 6 holding frame 8 sensor 10 coil 13 high-frequency voltage generator 14 voltage detection means 15 rectifying / smoothing circuit 18 comparison circuit 19 low-pass filter

Claims (1)

[Claims] 1. A magnetic material ring having a large number of teeth provided at equal pitches on its peripheral surface is attached to a rotating raceway ring of a rolling bearing, and a magnetic material wound with a coil is attached to the teeth of the ring on a fixed side raceway ring. Installed facing each other, the coil has a high-frequency voltage adding means, a rectifying and smoothing circuit for removing a carrier component from the output voltage of the coil, and a comparison circuit for comparing the smoothed signal with a set value. In the rotational speed detecting device, the output value of the rectifying / smoothing circuit is connected to the set value input terminal of the comparison circuit via a low-pass filter having a break frequency of several Hz or less, and the rotational speed detecting device of the rolling bearing is characterized. ..