JP2829538B2 - Torque detector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque detecting device for detecting a torque of a rotating shaft driven to rotate, and more particularly, to two magnetic recording media separated from each other on the rotating shaft. And a device that detects torque based on the phase difference between the two signals when the signals recorded on the signals are reproduced.

(Prior Art) In recent years, the need for torque detection in automobiles has been increasing. In particular, in an automatic transmission using a torque converter, a significant improvement in its characteristics is expected by detecting the torque of the output shaft. The necessity of torque detection is not limited to automobiles, but especially when applied to automobiles, the range of detected torque is wide,
It is necessary to accurately detect torque fluctuation.

2. Description of the Related Art Conventionally, as a torque detection device, a device that measures a torsion angle of a rotating shaft due to a torque load and obtains torque from the torsion angle is widely known. More specifically,
2. Description of the Related Art There is known an arrangement in which at least two rotary encoders are arranged on a rotating shaft to be measured. That is, the torsion angle is obtained from the phase difference Δt between the detection signals from the individual encoders, and is converted into torque.

The types of encoders include those using optical means, those using magnetic means, and those using magnetic recording means. The means is best. As a conventional technique using a magnetic recording rotary encoder, there is known a technique in which a rotating disk or a drum having a magnetic layer on which a magnetic signal is recorded in advance is fixed to a rotating shaft, and a magnetic sensor is disposed at a predetermined position facing the rotating disk or drum. (See, for example, Japanese Utility Model Application Laid-Open No. Sho 62-150644 and Japanese Patent Application Laid-Open No. Sho 62-239031).

(Problems to be Solved by the Invention) However, in the related art using the above-described magnetic recording rotary encoder, since the torsional distortion remains and accumulates on the rotating shaft, the signal recorded on the rotating disk or the drum and the detection sensor Are gradually shifted, and the accuracy of torque detection deteriorates with time.

In order to solve such a problem, a magnetic recording / reproducing head may be provided instead of the above-described magnetic sensor, and a signal may be recorded on a magnetic recording medium at any time using the magnetic head. That is, two magnetic recording media are fixed at a predetermined distance from each other in the axial direction with respect to the rotation axis, and a magnetic head is provided so as to face each of these magnetic recording media. A recording circuit that sends a recording signal of a predetermined frequency to each of the heads and records a position signal on a magnetic recording medium, and compares the phases of reproduction signals output by the two magnetic heads that read the position signal, and compares the comparison. And a torque calculating means for calculating a torque applied to the rotating shaft based on the result, thereby realizing a torque detecting device capable of appropriately rewriting a signal stored in the magnetic recording medium.

(Problems to be Solved by the Invention) The torque detection device having the above configuration has a wide range of torque detection and can prevent deterioration of the torque detection accuracy over time, but has another problem. I understood.

That is, an inductive type magnetic head is generally used. At this time, if the relative speed between the magnetic head and the magnetic recording medium is high, the reproduced signal of the magnetic head is indicated by C in FIG. 3 (1). In contrast to the sinusoidal waveform, if the relative speed is low, the reproduced signal will have a pulsed differential waveform as shown at D in FIG. More specifically, the magnetic signal reproduction output V from the magnetic head is represented by φ as the effective magnetic flux and n as the number of coil turns. And the reproduction output V depends on the time change of the magnetic flux φ.

In the case where the waveform of the reproduction signal changes as described above, the reproduction signal is directly input to the subsequent signal processing circuit when the rotation axis is rotating at high speed, whereas when the rotation axis is rotating at low speed, Complicated and troublesome signal processing is required, such as once converting a reproduced signal into a sine waveform and then inputting it to the subsequent stage.

In order to avoid the complication of the signal processing, only in a relatively low rotation region where the reproduced signal waveform is always a pulse-like differential waveform, or in a relatively high rotation region where the reproduced signal waveform is always a sine waveform. As a result, torque detection cannot be performed, which makes it difficult to apply to torque detection in the above-described automobile.

Note that it is conceivable that the frequency of the recording signal is considerably increased so that the reproduced signal always has a sine waveform even when the relative speed is low. However, in such a case, if the relative speed at the time of torque detection is high, the frequency of the reproduction signal becomes extremely high, which may deviate from the frequency characteristics of a signal reproduction system such as a magnetic head, making it impossible to detect torque.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a torque detection device that can accurately detect torque over a wide rotation speed region of a rotating shaft and that can easily process a reproduction signal from a magnetic head. It is intended to provide.

(Means for Solving the Problems) The torque detecting device of the present invention includes the two magnetic recording media as described above, the magnetic heads respectively provided for the two magnetic recording media, a recording circuit, and torque calculating means. A speed detecting means for detecting a relative speed between the magnetic head and the magnetic recording medium (usually the magnetic head is fixed, in which case it is synonymous with the rotation speed of the rotating shaft); Recording frequency control means for controlling the frequency of the recording signal to be applied so as to increase in accordance with an increase in the relative speed detected by the speed detection means.

Another torque detecting device according to the present invention is a torque detecting device including two magnetic recording media as described above, a magnetic head provided for each of the magnetic recording media, and torque calculating means. A speed detection unit, a recording frequency control unit also similar to the above, and a detection point including a plurality of magnetic points and the like arranged at equal pitches along a circumferential direction on a rotating shaft on which the magnetic recording medium is fixed, A circuit for detecting the plurality of detection points when the rotation shaft is rotated, and generating a reference signal having a frequency defined by the pitch of the detection points and the rotation speed of the rotation shaft; and A recording signal having a frequency corresponding to the frequency of the reference signal is sent to a magnetic head to record a position signal.

(Operation) As shown in (1) and (2) of FIG. 2, a magnetic recording layer 2 is formed on the peripheral surface of a rotating shaft 1 rotated in the direction of arrow A, and a magnetic head is formed on the magnetic recording layer 2. Consider a case in which a position signal is recorded by using No. 3. In the following, the relative speed between the magnetic head and the magnetic recording medium is considered as the rotation speed of the rotating shaft.

Here, first, assuming that the frequency of the recording signal is fixed, the interval between the magnetic points Mp to be recorded is approximately the same as FIG. 1A when the rotation speed of the rotating shaft 1 at the time of recording the position signal is relatively low.
When the rotation speed of the rotating shaft 1 is relatively high as shown in the drawing, the rotation speed becomes relatively large as shown in FIG.

The waveforms of the reproduced signals obtained by reading the magnetic points Mp shown in FIGS. 2 (1) and 2 (2) are shown in association with the rotational speed R at the time of reading.
It becomes like (2). That is, the lower the number of rotations at the time of recording the position signal, the higher the frequency of the reproduced signal as a whole.
Therefore, if the recording state of FIG. 2 (1) reads during speed while reproducing signals by R ₁ or a sinusoidal waveform, if the recording state of FIG. 2 (2), at the time of reading Rotation speed is R
If it does not exceed ₂ (R ₁ <R ₂ ), the reproduced signal will not have a sine waveform.

Therefore, if not performed conversion of the reproduced signal waveform described above, the rotational speed region capable torque detection is a range reproduced signal waveform of the common B ₁ or B _2.

Next, a case where the recording signal frequency is controlled in accordance with an increase in the number of rotations at the time of recording the position signal as in the apparatus of the present invention will be considered. In this case, if the number of revolutions during signal recording is relatively high, the recording signal frequency is increased, and the magnetic point Mp at that time is increased.
Is smaller than the state shown in FIG. 2 (2).
That is, this magnetic point interval approaches the state shown in FIG. 2 (1). Therefore, the relationship between the reading rotational speed R and the reproduced signal waveform at this time is close to the state shown in FIG. For purposes of explanation easier, if the recording speed is relatively high, if the magnetic point interval is the same as the state of FIG. 2 (1), said region B ₂ rpm range B ₂ wider than ' In (2), the reproduction signal waveform is adjusted to a constant (sine waveform).

Conversely, if the rotation speed at the time of recording the position signal is relatively low, even if the recording signal frequency is decreased, the recording signal frequency will increase as the rotation speed increases. Thus, if the rotation speed during recording is relatively low, and the interval between the magnetic points Mp is desired to be equal to, for example, the state shown in FIG. 2B, the reproduced signal waveform at that time is shown in FIG. 3B. It is the same as the state. Therefore, in this case,
In a wide speed range B ₁ 'than the region B _1, so that the reproduced signal waveform is aligned to the constant (differential waveform).

As is clear from the above description, if the recording signal frequency is controlled so as to be proportional to the rotation speed at the time of recording the position signal, the magnetic point interval becomes constant in any case. Is always constant. In order to suppress the fluctuation of the reproduction signal frequency, it is most preferable to use such a method. However, when applying the method to an actual device, one or more rotation speeds at the time of recording the position signal are taken into consideration in consideration of the device cost and the like. Set the threshold for
The recording signal frequency may be switched to a larger value each time the rotation speed exceeds each threshold value.

In addition, the frequency of each recording signal that can be changed according to the number of revolutions during recording may be determined according to the requirement whether the reproduction signal waveform is always a sine waveform or always a differential waveform.

A detection point as described above is provided on the rotation axis, a reference signal having a frequency defined by the pitch of the detection point and the rotation speed of the rotation axis is generated, and a recording signal having a frequency corresponding to the frequency of the reference signal is generated. In the torque detection device of the present invention in which the recording circuit is configured to send the signal to the magnetic head, the frequency of the storage signal changes in proportion to the fluctuation of the rotation speed of the rotating shaft during the recording of the position signal. Is always recorded at a constant pitch corresponding to the pitch of the detection points, regardless of the rotational speed.

(Examples) Hereinafter, the present invention will be described in detail based on examples shown in the drawings.

FIG. 1 shows a torque detecting device according to one embodiment of the present invention. For example, a rotating shaft 10, which is an output shaft of an automatic transmission for an automobile, rotates around its long axis by receiving a driving force of an engine (not shown). As an example, the rotating shaft 10 has a left end connected to the engine side and a right end connected to a load.

On the outer periphery of the rotating shaft 10, two magnetic recording layers 11, 12 are provided at a predetermined distance from each other. Such magnetic recording layers 11 and 12 are applied or printed on the surface of the rotating shaft 10 with a coating material in which a magnetic powder such as ferrite is dispersed in a binder such as an epoxy resin, and further used in a tape recorder or the like. The tape can be formed by bonding the tape to the surface of the rotating shaft 10.

In addition, inductive magnetic heads 13 and 14 are arranged close to and opposed to the magnetic recording layers 11 and 12, respectively. These magnetic heads 13 and 14 are connected to a recording circuit 17 and an amplifier 18 via storage / reproduction switching circuits 15 and 16, respectively. This amplifier 18 is connected to a waveform shaping circuit 20 through a low-pass filter 19.
The waveform shaping circuit 20 is connected to a torque calculation circuit 21.

On the other hand, a gear 30 is fixed to the rotating shaft 10, and an electromagnetic pickup 31 is arranged to face the peripheral surface of the gear 30. When the gear 30, that is, the rotating shaft 10 is rotating, the electromagnetic pickup 31 emits an output S1 corresponding to the rotation speed. The rotation speed detector 32 receives the output S1, and determines the rotation speed of the rotation shaft 10 based on the output S1. The rotation speed detector 32 inputs a signal S2 indicating the obtained rotation speed to the comparison circuit 33.

Note that the rotation speed of the rotating shaft 10 uniquely corresponds to the relative speed between the magnetic recording layers 11 and 12 and the magnetic heads 13 and 14. Therefore, in the present embodiment, the gear 30, the electromagnetic pickup 31, and the rotation speed The number detector 32 constitutes a means for detecting the relative speed.

Next, the torque detecting operation according to the above configuration will be described. When the rotating shaft 10 is rotating while being released from the load, the recording circuit 17 issues a storage signal S4 including a pulse signal of a predetermined frequency. The frequency of the recording signal S4 is selected to one of two values, which will be described later. At this time, the recording / reproduction switching circuits 15 and 16
The recording instruction state is set, and therefore the recording signal S4
Is applied to the magnetic heads 13 and 14, respectively. As a result, the magnetic recording layers 11 and 12 record position signals composed of a series of magnetic points arranged at equal intervals in the circumferential direction of the rotating shaft 10.

At the time of torque detection, the recording / reproduction switching circuits 15 and 16 are set to a reproduction instruction state. Thereby, the magnetic head 13,
From 14 are output reproduction signals S5 and S6 obtained by reading the position signals recorded on the magnetic recording layers 11 and 12, respectively. These S5 and S6 always have a sine waveform for a reason described later, and are input to the waveform shaping circuit 20 via the amplifier 18 and the low-pass filter 19. The waveform shaping circuit 20 shapes these reproduced signals S5 and S6 into square wave signals S5 'and S6' having the same period as each of them, and
Input.

The torque calculation circuit 21 receives the square wave signals S5 ', S5
Based on the period T of 6 'and the phase difference t between each other, the driving torque TRQ is determined as TRQ = A × (2πt / T). A in the above equation
Is a coefficient determined by the distance between the magnetic storage layers 11 and 12, the coefficient of transverse elasticity and the diameter of the rotating shaft 10. The torque calculation circuit 21 outputs a signal St indicating the value of the torque TRQ thus obtained.
Is output.

Next, reproduction signals S5, S6 output from the magnetic heads 13, 14
Will be described with respect to the fact that a sine waveform is always obtained irrespective of the rotation speed of the rotating shaft 10 at the time of torque detection. When recording the position signals on the magnetic recording layers 11 and 12 as described above, the comparison circuit 33 receives the rotation speed signal S2 output from the rotation speed detection base 32 and receives the signal.
S2 is compares the magnitude of the rotation speed with a predetermined threshold value N ₀ shown. Note this threshold N ₀ is set to, for example, 1/2, etc. of the maximum rotation speed Nmax of the rotary shaft 10. The comparison circuit 33 inputs the signal S3 indicating the comparison result to the recording circuit 17.

Recording circuit 17 receives the signal S3, the frequency of the speed have in the case of less than the threshold value N ₀ recorded signal S4 of the rotary shaft 10 to f _1,
On the other hand, when the rotational speed of the rotary shaft 10 exceeds the threshold value N ₀ sets the frequency of the recording signal S4 to _{f 2 (f 1 <f 2} ). By setting the frequency of the recording signal S4 in accordance with the rotation speed of the rotating shaft 10 during recording in this manner, for the same reason as described above,
It is possible to prevent the correspondence between the rotation speed at the time of torque detection and the frequency of the reproduction signals S5 and S6 from being significantly different between the case where the position signal is recorded under high rotation and the case where the position signal is recorded under low rotation.
Therefore, by appropriately setting the _two frequencies f ₁ and f ₂ , the waveforms of the reproduced signals S5 and S6 are always sinusoidal regardless of the rotation speed of the rotating shaft 10 at the time of torque detection. It can be a waveform.

In order to always sinusoidal waveform of the reproduction signal S5, S6, which is advantageously a higher frequencies f _1, f _2, them correctly and too high frequencies of the reproduced signal S5, S6 Sometimes it is impossible to detect. Therefore, these frequencies f ₁ and f ₂ are determined by the reproduction characteristics of the magnetic heads 13 and 14,
It is necessary to determine in consideration of the characteristics of the amplifier 18 and the low-pass filter 19 as well.

On the other hand, depending on the settings of the frequencies f ₁ and f ₂ , the waveforms of the reproduction signals S5 and S6 can always be differentiated.

Also, the magnetic recording medium has a rotating shaft as in the above embodiment.
In addition to forming the disk parallel to the peripheral surface of the disk 10, the disk may be fixed to the rotating shaft 10 and formed on the surface of the disk.

Further, in order to detect the number of rotations of the rotating shaft 10, in addition to the above configuration, for example, a slit plate fixed to the rotating shaft 10 having a number of slits arranged at equal intervals in the circumferential direction of the rotating shaft, and the slit An optical pickup having a light-emitting element and a light-receiving element opposed to each other via an optical pickup may be employed. Further, as the rotation speed detecting means, a means comprising a magnetic recording layer similar to the magnetic recording layers 11 and 12 and a magnetic head for reading a magnetic pattern recorded thereon may be used.

Next, a second embodiment of the present invention will be described with reference to FIG. In FIG. 4, elements that are the same as the elements in FIG. 1 are given the same reference numerals, and descriptions thereof will be omitted.

In the apparatus shown in FIG. 4, magnetic recording layers 41 and 42 similar to the magnetic recording layers 11 and 12 are formed on the peripheral surface of the rotating shaft 10,
A magnetic head is provided facing these magnetic recording layers 41 and 42, respectively.
43 and 44 are provided. When the rotating shaft 10 is previously rotated at no load and at a constant rotation speed, the magnetic recording layers 41 and 42 use a storage circuit (not shown) and the magnetic heads 43 and 44 to accurately align a magnetic dot sequence at a predetermined pitch. (Detection point sequence) is written. These magnetic dot sequences are written at a larger pitch on the one recorded on one magnetic recording layer 41 than on the other magnetic recording layer 42.

When writing the position signals to the magnetic recording layers 11 and 12, the magnetic dot sequences recorded on the magnetic recording layers 41 and 42 are detected by the magnetic heads 43 and 44, respectively.
Sine wave outputs S7 and S8 are input to the switching circuit 45. This switching circuit 45 has an output S3 of the comparison circuit 33,
10 a signal indicating a comparison result between the rotational speed with a predetermined threshold value N ₀ also inputted. Said switching circuit 45, the output S7 in the magnetic head 43 when the rotation speed is less than or equal to the threshold N ₀ is the rotation axis 10, when the rotational speed of the rotary shaft 10 exceeds the threshold value N ₀ is the magnetic The output S8 of the head 44 is input to the waveform shaping circuit 46.

The waveform shaping circuit 46 receives the input sine wave output S7 or S8
(See (1) in FIG. 5) is shaped into a square wave signal S9 (see (2) in FIG. 5) having the same period as that, and the resulting signal is input to the counter 47. Each time the counter 47 counts this signal S9 by a predetermined number, it outputs a pulse signal S10 as shown in FIG. 5 (3) and sends it to the recording circuit 50. Recording circuit 50
Makes the cycle of the recording signal S4 coincide with the cycle of the pulse signal S10 as the reference signal.

By doing so, even if the rotation speed of the rotating shaft 10 fluctuates during the recording of the position signal, the sequence of magnetic points recorded as the position signal on the magnetic recording layer 11 or 12 is changed to the magnetic recording layer 41 or 42.
In this case, recording can be performed at exactly the same pitch in correspondence with the pitch of the magnetic dot sequence that is accurately recorded.

Or the frequency of the street recording signal S4 description, if the rotational speed of the rotary shaft 10 at a position signal recorded below the threshold value N _0, based on the magnetic point pitch of one magnetic recording layer 41, also the rotation speed If is greater than the threshold value N _0, it is defined based on the magnetic point pitch of the other magnetic recording layer 42. And these pitch of both magnetic point column because they become as described above in relation to each other, when the rotation speed of the rotary shaft 10 is equal to or less than the threshold value N _0, a recording signal frequency when exceeding the threshold value N ₀ Are f ₁ and f ₂ respectively, in this case also f ₁ <f ₂ .

When a magnetic recording medium is used for detecting the rotation speed of the rotating shaft 10, a magnetic point sequence for detecting the rotation speed is recorded on the magnetic storage layer 11 or 12, and the magnetic dot sequence is recorded on a magnetic head other than the magnetic head 13 or 14. You may make it read by a sensor (an inductive magnetic head, a magnetoresistive head, etc.).

(Effect of the Invention) As described in detail above, the torque detection device of the present invention detects the rotation speed of the rotating shaft at the time of recording the position signal, and sets the recording signal frequency higher as the rotation speed increases. Therefore, it is possible to prevent the correspondence between the rotation speed at the time of torque detection and the reproduction signal frequency from being significantly different between the case where the rotation speed at the time of recording is relatively low and the case where the rotation speed is relatively high.

Therefore, according to the present device, the reproduction signal waveform can be made constant over a wide rotation speed region of the rotation axis at the time of torque detection, and therefore, a complicated signal processing circuit for coping with the waveform change becomes unnecessary. Thus, the torque can be accurately detected over a wide rotation speed range.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing an apparatus according to a first embodiment of the present invention, FIG. 2 is an explanatory view for explaining a rotation axis rotation speed and a magnetic point interval at the time of recording a position signal, and FIG. FIG. 4 is an explanatory diagram showing the correspondence between the rotation speed of the rotating shaft at the time and the reproduction signal waveform for the case where the rotation speed at the time of recording the position signal is low and the case where it is high. FIG. 5 is a graph showing the output of the magnetic head, the waveform shaping signal thereof, and the waveform of the recording signal period defining pulse signal in the device of the second embodiment. 10 ... rotary axis, 11, 12, 41, 42 ... magnetic recording layer 13, 14, 43, 44 ... magnetic head 15, 16 ... recording / reproduction switching circuit 17, 50 ... recording circuit, 20, 46 …… Waveform shaping circuit 21 …… Torque calculation circuit, 30 …… Gear 31 …… Electromagnetic pickup, 32 …… Rotation speed detector 33 …… Comparison circuit, 45 …… Switching circuit 47 …… Counter

Claims (3)

(57) [Claims] 1. Two magnetic recording media fixed at a predetermined distance from each other in the axial direction with respect to a rotation axis, a magnetic head provided to face each of these magnetic recording media, A recording circuit that sends a recording signal of a predetermined frequency to each of the magnetic heads and records a position signal on the magnetic recording medium, and compares the phases of reproduction signals output by the two magnetic heads that read the position signal. A torque calculating unit that calculates a torque applied to the rotating shaft based on the comparison result; a speed detecting unit that detects a relative speed between the magnetic head and a magnetic recording medium; and a frequency detecting unit that detects the frequency of the recording signal. A recording frequency control means for controlling the relative speed to increase in accordance with an increase in the relative speed detected by the means. 2. A magnetic head fixed to a rotating shaft at a predetermined distance from each other in the axial direction, a magnetic head provided to face each of these magnetic recording media, A plurality of detection points disposed at equal pitches on the rotation axis over the circumferential direction, when the rotation axis is rotated, the plurality of detection points are detected, and the pitch of the detection points and the rotation axis A circuit for generating a reference signal having a frequency defined by a rotation speed; and a recording signal for sending a recording signal having a frequency corresponding to the frequency of the reference signal to each of the magnetic heads to record a position signal on the magnetic recording medium. A circuit for comparing the phases of the reproduced signals output by the two magnetic heads that have read the position signal, and calculating a torque applied to the rotating shaft based on the comparison result; Speed detection means for detecting a relative speed between the recording medium and the magnetic recording medium; andrecording frequency control means for controlling the frequency of the recording signal so as to increase in accordance with an increase in the relative speed detected by the speed detection means. A torque detector, comprising: 3. The torque detecting device according to claim 2, wherein the detection point is a magnetic point, and the circuit for generating the reference signal detects the magnetic point.