JPH0587821A - Rotational speed detecting device for rolling bearing - Google Patents

Abstract

PURPOSE:To provide a rotation detecting device capable of detecting rotation accurately from low speed zone and high in durability against high temperature. CONSTITUTION:A pulsar ring 4 is installed on a rotating outer ring 3 of a rolling bearing 1, and a detecting ring 7 is installed on an stationary inner ring 2. Then multiple teeth 9 and 10 of equal pitch are provided around the periphery of these both rings 4 and 7, respectively, and a coil L is wound on the detecting ring 7. The coil L is excited by high-frequency voltage and, when the rings 4 and 7 are rotated relatively, an inductance of the coil L is varied due to variation in magnetic resistance. By extracting the variation, the rotational speed of a rolling bearing can be obtained.

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 is used, for example, for detecting the rotation speed of a wheel in a vehicle and the rotation angle of a steering shaft.

[0002]

2. Description of the Related Art In an anti-skid braking system installed in an automobile, it is required to accurately detect the rotational speed of wheels from a low speed to a high speed range.

Conventionally, such wheel rotation speed detection is
A pulsar ring, which has a large number of gear-shaped teeth on its peripheral surface, is attached to a rotating member, and an electromagnetic pickup is faced to the peripheral surface of the pulsar ring, and changes in magnetic flux caused by rotation of the pulsar ring are detected as voltage changes. Is done in a way.

However, this method has a drawback in that the output voltage is lowered when the wheel rotation speed becomes low, so that the detection accuracy of the rotation speed is remarkably deteriorated, and in particular, the detection cannot be performed near the 0 speed.

On the other hand, a pulsar ring having N and S poles alternately magnetized on the peripheral surface is attached to a rotating member, and a magnetic conversion element such as a Hall element is opposed to the pulsar ring to detect the rotation speed. A method is being considered.

However, in the case of the above structure, since the magnetic conversion element is usually composed of a transistor having a PN junction, the allowable temperature is set low due to the heat resistance of the PN junction itself, and at the time of energization. Are limited to even lower available temperatures. For this reason, there is a problem that durability deteriorates in an atmosphere near the wheels, which is heated to a high temperature by a brake operation or the like.

Therefore, according to the present invention, the rotation speed can be accurately detected in a wide range from a low speed to a high speed range by mounting it on a rolling bearing which supports a rotating shaft, and the durability is lowered even in a high temperature atmosphere. It is an object of the present invention to provide a rotation detecting device that is stable and can operate stably.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention mounts rings made of magnetic material on both bearing rings of a rolling bearing with their peripheral surfaces facing each other. A large number of teeth having the same pitch and the same phase on the entire peripheral surface are provided on the peripheral surface, and a coil is wound around the fixed ring, and a high-frequency voltage adding unit and voltage change in the coil are detected on the coil. It was connected to the signal processing means.

The signal processing means includes a capacitor forming a resonance circuit with the coil, a circuit for rectifying and smoothing the signal of the resonance circuit, and a comparison circuit for comparing the smoothed signal with a reference value. However, the structure can be integrated into the connector.

The coil may be incorporated inside an oil seal provided on one of the bearing rings.

[0011]

In the above structure, when a high frequency voltage is applied to the coil to excite the coil, a magnetic circuit is formed between the rings attached to the bearing ring.

From this state, when the rolling bearing rotates and each ring relatively rotates, the magnetic resistance of the magnetic circuit changes. This change in magnetic resistance changes the inductance of the coil, so the change is extracted as a voltage change,
By comparing it with the reference value, the rotation speed of the bearing ring can be detected.

In the above structure, the rotation speed is detected from the change in the inductance of the coil, so that the rotation speed can be accurately detected even in the zero speed or the low speed range in the vicinity thereof.
In addition, a magnetic ring or coil with high heat resistance can be attached to the bearing, and high-frequency voltage adding means and signal processing means can be arranged separately from them, so stable speed detection can be performed even in the vicinity of a wheel that is in a high temperature state. ..

On the other hand, when a ring or a coil is installed inside the rolling bearing, it is desirable to seal the coil to protect it from lubricant and metal powder contained therein. In that case, the coil is integrated inside the oil seal. When it is assembled into the bearing, the dedicated seal member can be omitted, and the device can be compactly assembled into the bearing.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The rolling bearing 1 in FIG. 1 (a) is used by fixing the inner ring 2 and rotating the outer ring 3, and a pulsar ring 4 made of a ferromagnetic material is attached to the inner diameter surface of the outer ring 3 on the rotating side. ..

Further, a seal member 6 which is in sliding contact with an oil seal 5 attached to the outer ring 3 is attached to the outer diameter surface of the fixed inner ring 2, and a detection ring 7 is incorporated in the seal member 6 and the detection ring. The tip of 7 is the pulsar ring 4
Are mounted so that their peripheral surfaces face each other. The detection ring 7 is made of a ferromagnetic material, and the inner peripheral portion thereof is press-fitted and fixed to the outer diameter of the non-magnetic core metal 8 of the seal member 6.

The inner peripheral surface of the pulsar ring 4 is shown in FIG.
As shown in FIG. 5, a large number of gear-shaped teeth 9 are formed at an equal pitch over the entire peripheral surface. On the other hand, the outer periphery of the detection ring 7 is divided into four yokes 7a, 7b, 7c, 7d in the circumferential direction, and a large number of them are arranged on the outer peripheral surface of each of the yokes 7a to 7d at the same pitch as the teeth 9 of the pulser ring 4. Teeth 10
Are formed.

The teeth 9 and 10 of the pulsar ring 4 and the detection ring 7 are formed such that the circumferential length of the convex portion of the tooth is shorter than the length of the concave portion. In addition, each yoke 7a of the detection ring 7
The teeth 10 of each of the yokes 7a to 7d are in the state where the teeth 10 of one yoke 7a face the teeth 9 of the pulser ring 4, and the teeth 10 of all the other yokes 7b to 7c are the same as the teeth 9 of the pulser ring 4.
Are formed in the same phase on the entire peripheral surface of the detection ring 7 so as to face each other. In addition, these rings 4,
In No. 7, a high-frequency magnetic field acts, so that when formed by laminating silicon steel plates, good magnetic characteristics can be obtained.

Further, each yoke 7a, 7 of the detection ring 7 is
The coils L1 and L are respectively attached to the necks of b, 7c and 7d.
2, L3 and L4 are wound. Each coil L
1 to L4 are respectively connected in series as shown in FIG. 1A (hereinafter, the entire connected coils L1 to L4 are referred to as a coil L), and a capacitor 11 is connected in parallel to both ends of the coil L to form an LC. A resonance circuit is formed, and the resonance circuit is further provided with a high frequency voltage adding means 12 and a signal processing means 1.
3 is connected.

The high frequency voltage adding means 12 oscillates a high frequency voltage of several tens of kHz consisting of a sine wave to the coil L, and by applying a high frequency voltage that oscillates to the coil L, the coil is excited.

On the other hand, the signal processing means 13 compares the smoothed signal with a rectifying circuit 14 for inputting the output voltage of the coil L, a smoothing circuit 15 for smoothing the rectified signal, and a preset reference value m. And a comparison circuit 16 for

The signal processing output 13, together with the high frequency voltage applying means 12, is integrally incorporated in the power source and the output signal connector provided at a position distant from the rolling bearing 1. Further, the signal processing means 13 and the coil L are connected by a coaxial cable 17 to block external noise.

The circuit speed detecting device of the embodiment has the structure as described above, and its operation will be described below.

Now, when the coil L is excited by the high frequency voltage by the high frequency voltage adding means 12, each coil L1, L
A magnetic circuit is formed between 2, L3, L4, the detection ring 7 and the pulser ring 4.

In this state, when the rolling bearing 1 rotates and the pulser ring 4 and the detection ring 7 rotate relative to each other, the magnetic resistance of the magnetic circuit changes periodically and the inductance of the coil L also changes synchronously.

In this case, since the coil L and the capacitor 11 connected in parallel form an LC resonance circuit, when the coil L is excited at a constant frequency f ₀ , the inductance of the coil L changes, so that the amplitude of the resonance circuit changes. Changes.
When the output voltage is rectified and smoothed by the signal processing means 13, the carrier component f ₀ is removed and an output corresponding to the change in inductance is obtained.

Next, when this output signal is compared with a constant reference value in the comparison circuit 16, a rectangular wave signal accompanying the rotation of the pulser ring 4 can be obtained.

FIG. 3 shows a second embodiment. In this example,
The detection ring 20 is formed in a U-shaped cross section, and the coil L is wound inside the detection ring 20. The other structure is the same as that of the above-mentioned embodiment, and the description thereof is omitted.

On the other hand, FIG. 4 shows a third embodiment. In this example, an oil seal 21 made of rubber or the like is attached to the outer diameter surface of the inner ring 2, and the detection ring 22 and the coil L are integrally incorporated in the oil seal 21 by molding. Reference numeral 23 is a coaxial cable that connects the coil L and the signal processing means. In the above structure, FIG.
Since it is not necessary to provide the seal member 6 for sealing the coil L as shown in (a) separately from the oil seal 5, the internal structure of the bearing can be simplified and the device can be made compact. Since other structures and signal processing structures are the same as those of the embodiment shown in FIGS. 1 and 2,
The description is omitted.

In each of the above-described embodiments, an example in which the outer ring of the rolling bearing is rotated has been shown, but the present invention can be similarly implemented when the inner ring is rotated. In this case, the pulsar ring is attached to the rotating inner ring and the detection ring is attached to the outer ring.

[0031]

As described above, according to the present invention, a ring having teeth is attached to both races so as to face each other, a high frequency voltage is applied to a coil wound around one of the rings, and the ring is rotated relative to the coil. Since the rotation speed is detected by the change in the inductance of the coil, it is possible to accurately detect the rotation speed in a wide range from the 0th speed and its low speed range to the high speed range.

Further, since the signal processing means including a transistor and the like can be arranged separately from the magnetic material ring or coil incorporated in the bearing, durability is not deteriorated even in a high temperature atmosphere, and stable speed is maintained. Detection can be performed.

[Brief description of drawings]

FIG. 1A is a sectional view showing an internal structure of a rolling bearing of an embodiment, and b is a block diagram showing a signal processing structure of the same.

FIG. 2 is a front view showing the pulsar ring and the detection ring of the above.

FIG. 3 is a sectional view showing a second embodiment.

FIG. 4 is a sectional view showing a third embodiment.

[Explanation of symbols]

 1 rolling bearing 2 inner ring 3 outer ring 4 pulser ring 7 detection ring 9, 10 teeth 12 high frequency voltage applying means 13 signal processing means 20 detection ring 21 oil seal 22 detection ring L coil

Claims (3)

[Claims] 1. Rings made of a magnetic material are attached to both races of a rolling bearing, with their circumferential surfaces facing each other.
A large number of teeth having the same pitch and the same phase on the entire peripheral surface are provided on the peripheral surfaces of both rings, and a coil is wound around the fixed ring, and a high-frequency voltage adding means and a voltage change in the coil Speed detecting device for rolling bearings, which is formed by connecting with signal processing means for detecting. 2. The signal processing means comprises a capacitor that forms a resonance circuit with the coil, a circuit that rectifies and smoothes the signal of the resonance circuit, and a comparison circuit that compares the smoothed signal with a reference value. The rolling bearing rotational speed device according to claim 1, wherein the rolling bearing is integrated in the connector. 3. The rotation speed detecting device for a rolling bearing according to claim 1, wherein the coil is incorporated inside an oil seal provided on one of the bearing rings.