JPH05281244A - Detecting device of rotation - Google Patents

Abstract

PURPOSE:To obtain a detecting device of rotation which can detect the speed of rotation of a rotary shaft member precisely and simply. CONSTITUTION:When a rotary shaft member 10 rotates, a recording signal of a prescribed frequency is outputted to a magnetic recording head 14a, a position signal recorded thereby on a magnetic recording layer 12 is reproduced sequentially through a magnetic recording head 14b and a phase difference between a reproduction signal thus obtained and the aforesaid recording signal is detected. Since the position signal (magnetic pitch) is always rewritten for the rotation of the rotary shaft member 10, the magnetic pitch is fine at the time of low rotation and rough at the time of high rotation, and when there is a change in the rotation, recording is made with the nonuniformity in the pitch corresponding to the change. By detecting the magnetic pitch immediately, the state of the rotation can be detected. Accordingly, the speed of the rotation can be detected precisely without necessitating previous formation of highly precise magnetic pitches.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation detecting device for detecting a rotating state of a rotary shaft member such as a power transmission shaft of an automobile.

[0002]

2. Description of the Related Art Conventionally, a magnetic encoder (for example, Japanese Unexamined Patent Publication No. Sho 62-239) has been used as means for detecting the rotational state of a rotary shaft member, for example, the rotational speed.
No. 031) and optical encoders are known.
Among them, the magnetic encoder is configured such that the circumference of the rotary shaft member is divided into a predetermined number in advance by a magnetic scale, and the rotation speed is calculated based on this. In this case, the detection range and accuracy of the rotation speed largely depend on the number of divisions (the number of magnetic pitches) and the division accuracy. For example, if the number of pitches per revolution is small, the detection range and accuracy of the rotation speed may deteriorate, and it may not be suitable for detecting minute rotation fluctuations of the rotary shaft member. On the other hand, even if an attempt is made to increase the number of magnetic pitches, there is a limit naturally due to the size of the encoder, the performance of the magnetic recording layer forming the magnetic pitch, and the like. Further, in order to form the magnetic pitch, it is necessary to use magnetic recording means and magnetizing means with extremely high accuracy. In the conventional method, in order to obtain accuracy smaller than the magnetic pitch length, a method of interpolating the detection signal of the encoder and electrically dividing it is used, and therefore the configuration is very complicated.

Further, as a means for detecting the torque acting on the rotary shaft member, there has been conventionally known one in which two magnetic encoders are provided on the rotary shaft member and the torque is detected from the signal phase difference between them. Even in such a configuration, the detection accuracy and the detection range are limited due to the number of magnetic divisions of the encoder and the division accuracy. Even when the method of rewriting the number of magnetic pitches according to the situation by the magnetic recording / reproducing means is adopted, the recording accuracy at the time of rewriting becomes a big problem.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a rotation detecting device capable of accurately and easily detecting the rotation state of a rotary shaft member. Is.

[0005]

A rotation detecting device according to the present invention outputs a recording signal of a predetermined frequency to a magnetic recording head, whereby position signals recorded on a magnetic recording layer are sequentially transmitted through a magnetic reproducing head. By playing back and detecting the phase difference between the playback signal and the recording signal,
The rotation state detection utilizing the phase difference is made possible, thereby achieving the above object.

That is, as described in claim 1, the magnetic recording layer formed on the peripheral surface portion of the rotary shaft member and the magnetic recording layer close to the peripheral surface of the rotary shaft member so as to face the magnetic recording layer. A magnetic recording head and a magnetic reproducing head arranged at a predetermined angle in the circumferential direction of the rotary shaft member, and recording means for outputting a recording signal of a predetermined frequency to the magnetic recording head when the rotary shaft member is rotating. Reproducing means for sequentially reproducing position signals recorded on the magnetic recording layer by the recording means via the magnetic recording head, and reproducing signals reproduced by the reproducing means and the recording means. And a phase difference detecting means for detecting a phase difference with the signal.

The "magnetic recording layer formed on the peripheral surface of the rotary shaft member" may be a magnetic recording layer formed by coating or plasma spraying on the peripheral surface of the rotary shaft member. However, the rotating shaft member itself may be a magnetic recording layer formed by using a magnetically recordable material (magnetic material).

[0008]

As described above, when the rotary shaft member is rotating, a recording signal of a predetermined frequency is output to the magnetic recording head, and the position signal recorded on the magnetic recording layer is magnetically recorded. Play sequentially through the playhead,
Since the phase difference between the reproduction signal and the recording signal is detected, it is possible to detect the rotation state using this phase difference.

That is, since the position signal (magnetic pitch) is constantly rewritten with respect to the rotation of the rotary shaft member, the magnetic pitch becomes fine at low rotation and coarse at high rotation, and if there is fluctuation in rotation, Since the pitch irregularity is recorded according to the fluctuation, the state of rotation can be detected by immediately detecting the magnetic pitch.

Therefore, for example, if the rotation speed of the rotary shaft member is calculated on the basis of the phase difference detected by the phase difference detecting means as described in claim 2, as in the conventional case, the rotation speed is previously calculated. The rotation speed can be accurately detected without the need to form a highly accurate magnetic pitch.

When the frequency of the recording signal is set to a frequency proportional to the rotation speed of the rotary shaft member, the phase difference is constant regardless of the magnitude of the rotation speed when the rotation speed is constant. Therefore, as described in claim 4, the change rate of the phase difference is calculated based on the phase difference detected by the phase difference detecting means, and the rotating shaft member is calculated based on the phase difference change rate. If the rotational speed change rate is calculated, it is possible to accurately detect a minute rotational fluctuation without the need to previously form a highly accurate magnetic pitch as in the conventional case.

Further, as described in claim 5, a pair of rotation detecting devices according to claim 1 are provided at a predetermined interval in the axial direction of the rotary shaft member, and based on the phase difference detected from each of them. If the torque acting on the rotary shaft member is calculated, the torque can be accurately detected without the need to previously form a highly accurate magnetic pitch as in the conventional case.

As described above, according to the present invention, the rotational state of the rotary shaft member can be detected accurately and easily.

[0014]

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

FIG. 1 shows a first rotation detecting device according to the present invention.
It is a schematic block diagram which shows an Example, and FIG. 2 is the II direction arrow view.

This rotation detecting device is a device for detecting the rotation speed of the rotary shaft member 10 (for example, the output shaft of an automatic transmission for automobiles), and is formed in a ring shape on the outer peripheral surface of the rotary shaft member 10. The magnetic recording layer 12 and the magnetic recording heads 14a arranged at a predetermined angle θ in the circumferential direction of the rotary shaft member 10 so as to face the magnetic recording layer 12 and close to the outer peripheral surface of the rotary shaft member 10; A magnetic reproducing head 14b,
When the rotary shaft member 10 is rotating, the magnetic recording head 1
A recording circuit 16 (recording means) for outputting a recording signal E having a constant frequency f (= ωt) to 4a, and a position signal recorded by the recording circuit 16 on the magnetic recording layer 12 via the magnetic recording head 14a is magnetically reproduced. A reproducing circuit 18 (reproducing means) for reproducing through the head 14b, and a phase difference detecting circuit 20 (phase difference detecting means) for detecting a phase difference φ between the reproduced signal E ′ reproduced by the reproducing circuit 18 and the recording signal E. ) And a rotation speed calculation circuit 22 (rotation speed calculation means) for calculating the rotation speed N of the rotary shaft member 10 based on the phase difference φ.

Each of the magnetic recording layers 12 is formed by applying a magnetic coating in which magnetic powder such as ferrite is dispersed in a resin binder such as epoxy resin in a ring shape on the outer peripheral surface of the rotary shaft member 10. Alternatively, it can be formed by plating a metal cobalt film in a ring shape.

Next, the operation of this embodiment will be described.

The phase difference φ is expressed by the following equation (1).

Φ = (fθ / (2πN)) · 2π (rad) (1) That is, the phase difference φ is proportional to the frequency f of the recording signal E and the arrangement angle θ of the magnetic recording head 14a and the magnetic reproducing head 14b. However, it is inversely proportional to the rotation speed N of the rotary shaft member 10. Therefore, by setting f and θ to appropriate values, it is possible to accurately detect the rotational speed within the range that requires the rotational speed detection.

For example, the arrangement angle θ of both the heads 14a and 14b is π / 2, and the frequency f of the recording signal E is 1 kHz.
z (sinusoidal wave), the rotation direction of the rotary shaft member 10 is shown in FIG.
The arrow indicates the direction, that is, the direction from the magnetic recording head 14a to the magnetic reproducing head 14b.

At this time, the rotation speed of the rotary shaft member 10 is set to N
(Rps), the reproduced signal E'has a phase advanced from the recorded signal E by φ = (250 / N) · 2π (rad) (2) from the equation (1).

Therefore, the value in parentheses of the expression (2) for the rotation speed N is as shown in FIG. Assuming that the rotation speed N to be detected is about 10 rps (600 rpm), from FIG. 3, the rotation speed is about 0.
The phase shift amount changes by one cycle with a change of 4 rps (24 rpm). The sensitivity of the phase difference detection circuit 31 is set to one cycle (0 to 2
Rotation speed 1 if set to full scale with π)
With respect to 0 rps (600 rpm), 4% rotation fluctuation can be detected in full scale. In FIG. 4, the configuration of this embodiment is applied to an actual electric motor, and the rotation speed is 10 rp.
An example of measuring the rotation fluctuation around s (600 rpm) is shown. A variation of 4 cycles per one rotation of the shaft is shown. This means that the rotational fluctuation is accurately measured because the number of poles of the electric motor is four.

As described in detail above, when the rotary shaft member 10 is rotating, the recording signal E having a predetermined frequency is output to the magnetic recording head 14a, whereby the position signal recorded on the magnetic recording layer 12 is magnetically recorded. Since the phase difference φ between the reproduction signal E ′ and the recording signal E is detected by sequentially reproducing through the reproduction head 14b, it is possible to detect the rotation using the phase difference φ.

That is, since the position signal (magnetic pitch) is constantly rewritten with respect to the rotation of the rotary shaft member 10, the magnetic pitch is fine at low rotation and coarse at high rotation, and if there is rotation fluctuation. Recording is performed with pitch unevenness corresponding to the fluctuation, and the state of rotation can be detected by immediately detecting the magnetic pitch.

Therefore, by calculating the rotational speed N of the rotary shaft member 10 based on the phase difference φ, the rotational speed N is not required to previously form a highly accurate magnetic pitch as in the conventional case. Can be accurately detected.

Next, a second embodiment of the present invention will be described.

In the present embodiment, as shown in FIG. 5, the phase difference detecting circuit 2 is used in place of the rotation speed calculating circuit 22 of the first embodiment.
Rotation speed change rate calculation for calculating a change rate Δφ of the phase difference φ based on the phase difference φ detected by 0, and calculating a rotation speed change rate ΔN of the rotary shaft member 10 based on the phase difference change rate Δφ. In comparison with the point that the circuit 24 (phase difference change rate calculation means, rotation speed change rate calculation means) is provided and the first embodiment, the recording signal E is not the signal of the constant frequency f but the rotation of the rotary shaft member 10. The difference is that a frequency signal proportional to the speed N is used as the recording signal E.

By detecting the phase difference φ between the recording signal E and the reproduced signal E'of the recorded position signal, the rotational speed N ₁ at the portion of the rotary shaft member 10 where the recording signal E is generated. Then, it is possible to detect the difference between the rotation speed N ₂ and the rotation speed N ₂ at the site where the reproduction is performed.

That is, in this embodiment, since the recording frequency f = kN ₁ , the recording signal E is given by E = E ₀ cos (2πkN ₁ ) t (k: constant). Playback signal is N ₁
And N ₂ are equal to each other, they are detected with a constant phase difference φ ₀ from the equation (1) as shown in the following equation.

Φ ₀ = (θk / 2π) 2π (rad) (3) On the other hand, when there is a difference in rotation speed between the recording portion and the detection portion, φ = (θkN ₁ / 2πN ₂ ) 2π (rad) ( 4) Only the phase difference occurs.

When the phase difference change rate Δφ based on the phase difference φ _{0 in the} equation (3) is calculated, Δφ = φ−φ ₀ = φ ₀ (N ₁ / N ₂ −1) (5) The rotational speed change rate ΔN can be calculated by obtaining this Δφ.

As described above, according to the present embodiment, the frequency f of the recording signal is set to the frequency proportional to the rotation speed N of the rotary shaft member 10. Therefore, when the rotation speed N is constant, the frequency f may be large or small. Instead, the phase difference φ can be made constant, and the rate of change Δφ of the phase difference φ is calculated based on the phase difference φ detected by the phase difference detection circuit 20,
Since the rotational speed change rate ΔN of the rotary shaft member 10 is calculated based on the phase difference change rate Δφ, it is not necessary to previously form a highly accurate magnetic pitch, unlike the conventional case. It is possible to accurately detect minute rotation fluctuations.

Next, a third embodiment of the present invention will be described.

The present embodiment is a torque detecting device for detecting the torque acting on the rotary shaft member 10 by using the main part of the rotation detecting device according to the first embodiment.

As shown in FIG. 6, this torque detecting device has the above-described rotation detecting device (strictly speaking, the rotation speed calculating circuit 22 in the rotation detecting device is provided at a predetermined interval in the axial direction of the rotary shaft member 10. Except for the phase difference φ ₁ detected from each of the pair of rotation detecting devices,
A torque calculation circuit 30 (torque calculation means) for calculating the torque acting on the rotary shaft member 10 based on φ ₂ is provided.

As shown in FIG. 6, the rotary shaft member 10 in this embodiment is a crankshaft of a four-cylinder internal combustion engine 32, and magnetic recording layers 12 are formed on the shafts at both ends thereof. The magnetic recording heads 14a, 14a are arranged so as to face each of them. Further, magnetic reproducing heads 14b and 14b are arranged at positions separated from the magnetic recording heads 14a and 14a by a predetermined angle θ in the circumferential direction. Then, the internal combustion engine 32 is operated with the load 34 coupled to the crankshaft.

Next, the operation of this embodiment will be described.

A recording circuit 16 applies a recording signal of a constant frequency f to each of the magnetic recording heads 14a, 14a. The signals respectively detected by the magnetic reproducing heads 14b and 14b are input to the phase difference detecting circuit 20 together with the signal from the recording circuit 16, and the phase differences φ ₁ and φ ₂ of the reproduced signal with respect to the recording signal are detected. Then, the torque calculation circuit 30 calculates the torque acting on the crankshaft by the following equation (6) based on the phase differences φ ₁ and φ ₂ .

[0040]

[Equation 1]

Here, the value of the proportional coefficient K is K = πGd ⁴ / 32L G: elastic modulus of the shaft d: diameter of the shaft L: distance between measurement sites.

Although the torque of such an internal combustion engine changes greatly during one revolution of the crankshaft, this embodiment can also accurately detect such an instantaneous torque.

The above equation (6) will be described in more detail as follows.

It is assumed that the driving torque is applied to the rotary shaft member 10 from the unloaded state and the twist angle α of the rotary shaft member 10 between the two detection portions changes as shown in FIG. 7, for example.

In the unloaded state, the rotational speeds between the two detection parts are equal, and the detection phase difference φ _{1 at} each of them is
φ ₂ is equal. Here, when the twist shown in FIG. 7 occurs, a difference in rotational speed occurs between the two parts by dα / dt. In this embodiment, the difference in rotational speed is the difference between the reciprocal of the phase difference between the recorded signal and the reproduced signal at the two portions. Therefore, (dα / dt) = (1 / φ ₁ ) − (1 / φ ₂ ), and the time change rate dT / dt of the torque T at this time can be calculated by the following equation.

(DT / dt) = K (dα / dt) = K
((1 / φ ₁ )-(1 / φ ₂ )) Therefore, the torque value is

[0047]

[Equation 2]

It can be calculated by

As described above, according to this embodiment, the rotation detecting device 1 is provided at a predetermined interval in the axial direction of the rotary shaft member 10.
Since the torque T acting on the rotating shaft member 10 is calculated based on the phase differences φ ₁ and φ ₂ detected from each pair, a high-precision magnetic pitch is formed in advance as in the conventional case. It is possible to detect the torque with high accuracy without the need to do so.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of a rotation detection device according to the present invention.

FIG. 2 is a view taken along the line II-II in FIG.

FIG. 3 is a graph showing the operation of the first embodiment.

FIG. 4 is a waveform chart showing the operation of the first embodiment.

FIG. 5 is a schematic configuration diagram showing a second embodiment of the rotation detection device according to the present invention.

FIG. 6 is a schematic configuration diagram showing a third embodiment of the rotation detection device according to the present invention.

FIG. 7 is a graph showing the operation of the third embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 rotating shaft member 12 magnetic recording layer 14a magnetic recording head 14b magnetic reproducing head 16 recording circuit (recording means) 18 reproducing circuit (reproducing means) 20 phase difference detecting circuit (phase difference detecting means) 22 rotational speed calculation circuit (rotational speed calculation) 24) Rotation speed change rate calculation circuit (phase difference change rate calculation means, rotation speed change rate means) 30 Torque calculation circuit (torque calculation means)

Claims (5)

[Claims] 1. A magnetic recording layer formed on a peripheral surface of a rotating shaft member, and a magnetic recording layer adjacent to the peripheral surface of the rotating shaft member so as to face the magnetic recording layer and having a predetermined angle in the peripheral direction of the rotating shaft member. A magnetic recording head and a magnetic reproducing head which are arranged at a position, a recording means for outputting a recording signal of a predetermined frequency to the magnetic recording head when the rotating shaft member is rotating, and the magnetic recording by the recording means. Reproducing means for sequentially reproducing the position signal recorded on the magnetic recording layer via the head via the magnetic reproducing head, and a position for detecting the phase difference between the reproduced signal reproduced by the reproducing means and the recording signal. A rotation detecting device comprising a phase difference detecting means. 2. The rotation detection according to claim 1, further comprising rotation speed calculation means for calculating the rotation speed of the rotary shaft member based on the phase difference detected by the phase difference detection means. apparatus. 3. The rotation detecting device according to claim 1, wherein the predetermined frequency is set to a frequency proportional to a rotation speed of the rotary shaft member. 4. A phase difference change rate calculating means for calculating a change rate of the phase difference based on the phase difference detected by the phase difference detecting means, and a phase difference change calculated by the phase difference change rate calculating means. 4. The rotation detecting device according to claim 3, further comprising rotation speed change rate calculating means for calculating a rotation speed change rate of the rotary shaft member based on the rate. 5. A torque detecting device for detecting a torque acting on a rotary shaft member by using the rotation detecting device according to claim 1, wherein the rotary shaft member has a predetermined interval in an axial direction thereof.
A pair of the rotation detecting devices described above is provided, and a torque calculating means for calculating a torque acting on the rotating shaft member based on a phase difference detected from each of the pair of rotation detecting devices is provided. Characteristic torque detection device.