JPH0726881B2 - Torque detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a torque detection device using a magnetic encoder, and particularly to a torque detection suitable for detecting a relative displacement of a position caused by a twist of a shaft. Regarding the device.

[Conventional device]

The conventional device is Mitsubishi Electric Technical Report Vol.58 No.7, 1984, page 52,
As shown in FIG. 1, the torsion of the shaft is composed of the gears A and B and the electromagnetic picks arranged on the gears A and B, respectively. However, the magnitude of the output signal of the electromagnetic pick-up depends on the rotation speed of the gear, and the output signal becomes small at low speed, and there is a drawback that the output cannot be obtained at the time of stop.

[Problems to be solved by the invention]

In the above-mentioned conventional technique, the structure of the electromagnetic pickup is arranged so as to face each of two sets of rotary drums or rotary disks. Therefore, when assembling and adjusting the torque detection device,
Each electromagnetic pick-up must be adjusted individually, which requires a lot of time, and a positional error occurs between the magnetic sensors, which lowers the detection accuracy.

An object of the present invention is to dispose each magnetoresistive effect element constituting the magnetic sensor on a one-chip so as to eliminate a positional error between the magnetic sensors during assembly and adjustment.

[Means for solving problems]

The present invention is formed by disposing a drive-side rotary drum mounted on the drive-side of a rotary shaft, a load-side rotary drum mounted on the load-side of the rotary shaft, and a fine magnet on the surface of the drive-side rotary drum. Drive-side signal track, load-side signal track formed by arranging fine magnets on the surface of the load-side rotating drum, and drive-side magnetoresistive effect element provided so as to face the drive-side signal track And a magnetic sensor having a magnetoresistive effect element on the load side provided so as to face the signal track on the load side, and one of the both rotary drums has a shaft mounting portion mounted on a rotary shaft and the shaft mounting portion. Has a cup-like shape with an extension extending from one part so as to be closer to the other rotating drum, and the two signal tracks are arranged at positions close to each other. The drive-side magnetoresistive effect element and the load-side magnetoresistive effect element are formed so as to be carried on the same substrate by vapor deposition etching or the like. It is characterized by detecting the torque applied to the.

[Action]

In the magnetoresistive effect element arranged on the one chip, two sets of magnetic sensors are accurately formed on the glass substrate by vapor deposition etching or the like. As a result, a positional error between the magnetic sensors during assembly and adjustment can be eliminated, so that a highly accurate torque detection device can be provided.

〔Example〕

Each embodiment of the magnetic sensor for torque detection according to the present invention will be described.

FIG. 1 is a schematic configuration diagram of a torque detection device according to an embodiment of the present invention. FIG. 2 is a sectional view of FIG. FIG. 3 is a partially developed view of FIG. 1, and FIGS. 4 to 6 are operation waveform explanatory diagrams thereof.

In FIGS. 1 and 2, 1 is a rotating shaft. 2,
Reference numeral 2'denotes a rotating drum, each of which has a cup-shaped shape, and has a minute gap Ls between the magnetic recording portions 3 and 3'for recording magnetic signals.
It is configured to approach each other. As described above, in the magnetic recording portions 3 and 3 ', magnetic signals of the N pole and the S pole are simultaneously recorded over the entire circumference by one recording head or the like to form a signal track portion. Reference numeral ₄ denotes a magnetic sensor composed of magnetoresistive effect elements (hereinafter referred to as MR elements) R _{1 to} R ₄ , which are opposed to the magnetic recording portions 3 and 3 ′ of the rotary drums 2 and 2 ′ and have a small gap ls. Placed through. In the MR elements R _{1 to} R ₄ formed on the _one chip, R ₁ and R ₂ are respectively provided in the magnetic recording portion 3 and R 1
₃ and R ₄ face the magnetic recording portion 3 ′. The MR elements R _{1 to} R ₄ described above are one-chip arranged at a predetermined position with a dimensional accuracy of several μm on a glass plate or the like by a thin film forming technique such as vapor deposition etching of a ferromagnetic material such as permalloy. Is. As described above, the magnetic sensor for torque detection of the present invention is
A major feature is that the magnetic sensors facing the pair of rotary drums are arranged on the one chip.

Here, the operation of the rotary drums 2, 2'and the magnetic sensor 4 will be described with reference to FIGS. FIG. 3 shows the magnetic recording unit 3, of the rotary drum 2, 2'shown in FIGS.
3 is an enlarged development view showing the arrangement of 3'and the magnetic sensor 4. FIG. The MR elements R ₁ and R ₂ and R ₃ and R ₄ are respectively separated by λ / 2 with respect to the recording wavelength (the distance between the N pole and the S pole) λ.
Further, the MR element group of R ₁ and R _{2 and} the MR element group of R ₃ and R ₄ are respectively
It is arranged so as to face the signal track portions M ₁ and M ₂ and is configured substantially linearly. This operation waveform is shown in FIG. Since the rotating drums 2 and 2'have the same operation in all, the rotating drum 2 is shown here. In FIG. 4, it is assumed that the magnetic recording unit 3 moves in the direction of the arrow shown in the figure by the rotation of the rotary drum 2. On the other hand, as is well known, the MR element has a characteristic that its resistance value decreases when any one of the magnetic field changes of the N pole and S pole of the magnetic signal is applied. When moved to, the resistance changes of the MR elements R ₁ and R ₂ are obtained in accordance with the recording wavelength λ, and each has a waveform with a λ / 2 phase shift. here,
When the MR elements R ₁ and R ₂ are connected to three terminals as shown in FIG. 5 (a) and a voltage V is applied to both ends, the voltage obtained from the output terminal e _A1 is E shown in FIG. 5 (b). _{It has} a waveform like _A1 . On the other hand, similarly, the MR elements R ₃ and R ₄ are also connected to three terminals as shown in FIG. 6 (a), and when a voltage V is applied to both ends, the MR elements R ₃ and R ₄ are output from the output terminal e _{A2 as} shown in FIG. 6 (d). A similar output waveform E _A2 is obtained. The phases of these output waveforms E _A1 and E _A2 are MR elements R ₁ , R ₂ and R ₃ , R ₄
Are arranged almost linearly, so that the output signals are almost in phase.

Here, in the torque detector of FIG.
When the motor on the drive side is attached and the load is attached on the load side, the shaft 1 is twisted by an angle θ in proportion to the load torque. This can be expressed by the following formula.

Where θ: twist angle (rad), G: axial shear coefficient (kg /
cm ² ), L: distance between drums (cm), D: shaft diameter (cm). The shear coefficient G is determined by the material of the shaft, and if the distance L between the drums and the shaft diameter D are determined, the torque T with respect to the twist angle θ can be known. Therefore, the torque T can be detected by measuring the torsion angle θ of the shaft 1. That is, the twist angle θ of the shaft 1 is, for example, as shown in FIG. 7, the phase difference θ between the outputs E _A1 and E _A2 of the one-chip magnetic sensor 4 at the zero crossing.
It is sufficient to measure _2- θ ₁ . That is, as shown in FIG. 7A, when the load torque is small, the amount of twist of the shaft 1 is also small, so the phase difference θ _{1 at} the zero crossing between the outputs E _A1 and E _A2 becomes small. On the other hand, when the load torque is large as shown in FIG. 7B, the amount of twist of the shaft 1 also increases, so the phase difference θ _{2 at the} zero cross becomes large. Therefore, the magnitude or change of the torque T can be detected by measuring the phase differences θ ₁ and θ ₂ . In this case, the torque is
The electrical angle of the output signal can be accurately detected within a range of approximately 180 degrees. As described above, according to the present invention, by configuring the MR element group of R ₁ and R _{2 and} the MR element group of R ₃ and R ₄ on one chip, the position between the elements at the time of mounting adjustment of the magnetic sensor There is an effect that an error can be eliminated, a highly accurate magnetic signal can be detected, and a highly reliable torque detection device can be provided.

In this embodiment, the MR element group of R ₁ and R _{2 and} the MR element group of R ₃ and R ₄ are arranged substantially linearly. However, as shown in FIG. in the MR element R _1, R ₂ as a method for obtaining a waveform which is shifted approximately 90 degrees phase, MR elements R _3,
It is also possible to adopt a configuration in which R ₄ is arranged by λ / 4 for each recording wavelength λ. By doing this, the outputs E _A1 , E of the magnetic sensor 4
_As shown in Fig. 9 (a), _A2 has a waveform that is 90 degrees out of phase with the electrical angle. Therefore, for example, just by looking at the magnitude of the phase difference θ with reference to the output E _A1 , the axis 1 will move in one direction. It is possible to obtain the effect that the forward and reverse directions of the torque T applied to the shaft 1 when the shaft is rotating can be determined. That is, when the torque T is applied to the shaft 1 in the opposite direction, as shown in FIG.
_N becomes θ _O <θ _n with respect to the phase difference θ _O when the torque T = 0 as shown in FIG. Further, when the torque in the positive direction is applied to the shaft 1, the phase difference θ as shown in FIG.
_p is the phase difference θ _O when torque T = 0, θ _O > θ _p
Becomes Furthermore, in the embodiment of FIG. 3, the signal output E _A1
Since E _A2 and E _A2 are in phase, if a recording error, a detection error, etc. occur, the zero crossing points will move alternately due to fluctuations in the output signals of each other, such as when the detected torque is very small, and the phase difference θ The reference signal (E _A1 or E _A2 ) changes in order to achieve this. However, in the embodiment of FIG. 8, the output E
_Since the phase difference between _A1 and E _A2 is approximately 90 degrees in terms of the electrical angle of the output signal, the reference signal (E _A1 or E _A2 ) does not change even if there is a recording error or detection error. Even with torque, the effect of stable measurement can be obtained. in this case,
The torque T can be measured within an electric angle of the output signal of approximately ± 90 degrees.

FIG. 10 shows that a reference position track M _Z1 capable of detecting a reference signal 5 of one pulse per one rotation is provided on one of the rotating drums 2 and 2 '(here, the rotating drum 2), and the reference position track M _Z1 is provided at a position opposite to this. , MR element R _Z1 for detecting the reference position to the magnetic sensor 4 and M
It is arranged in one chip together with R elements R _{1 to} R ₄ . The operation waveforms in this case are shown in FIG. 12 (the signal track M1 has been described above and therefore omitted). The MR element R _Z1 for detecting the reference position is connected to three terminals together with, for example, an external resistor and the like, and a voltage V is applied to both ends thereof. Therefore, the rotary drum 2
Is rotated, and only when the reference position signal 5 of the reference position track M _Z1 passes, MR for reference position detection as shown in Fig. 12 (a)
Since the resistance of element M _Z1 changes, the output voltage of output terminal e _Z1
E _Z1 is as shown in Fig. 12 (b). Generally this output E _Z1
Is subjected to waveform shaping by a comparator circuit or the like and used as a square wave output E _Z1 ′ as shown in FIG. By doing so, it is possible to obtain an effect that torque correction and the like can be easily performed based on the reference position signal E _Z1 . Furthermore, when used in combination with a motor or the like as the torque detection device, there is an effect that it can be used as an origin return signal for motor control.
In this embodiment, the reference position signal is one pulse for one rotation, but the number of pulses may be increased if necessary.

FIG. 11 shows the reference position tracks M _Z1 and M _Z2 capable of detecting the reference signals 5 and 5'one pulse at a time on both of the rotary drums 2 and 2'and the MR element for detecting the reference position opposite thereto. R _Z1 and R _Z2 are arranged on the magnetic sensor ₄ together with MR elements R _{1 to} R ₄ in a one-chip arrangement. By doing so, in addition to the effect shown in FIG. 10, the effect that the accurate origin position information on each of the load side and the motor side can be accurately detected can be obtained. In the example of FIGS. 10 and FIG. 11, provided with a signal track M _1, M ₂ in the innermost of the rotary drum 2, 2 'has a configuration facing each other at the shortest distance, the signal track M ₁ , M ₂ and the reference signal tracks M _Z1 and M _Z2 may be interchanged as necessary. In this case, the arrangement of the MR elements R _{1 to} R ₄ and R _Z1 , R _Z is also the signal track M ₁ , M.
₂ and the reference signal tracks M _Z1 and M _Z2 .

FIG. 13 shows that, in addition to the MR elements R ₁ , R ₂ and R ₃ , R ₄ facing the rotating drums 2, 2 ′ as compared with those of FIG. ₃ , R ₅ , R ₆ and R ₇ , R are newly added. ₈
MR elements are arranged in a phase of approximately λ / 4 with respect to the recording wavelength λ of the magnetic signal, and the rotary drum 2,
The two-phase signal having a phase difference of approximately 90 degrees in electrical angle of the output signal is obtained from each of the 2'magnetic signals. An example of operation waveforms in this case is the rotary drum 2 and the MR elements R ₁ , R ₂ ,
An explanation will be given using R ₅ and R ₆ . Fig. 14 shows an example of the operation waveform. 14 (a) and 14 (c) operate in the same manner as in FIGS. 14 (a) and 14 (b). The newly provided MR elements R ₅ and R ₆ are
_{Since the} λ / 4 phase is shifted with respect to ₁ and R respectively, the 14th
As shown in the figure (b), the resistance change of the MR elements R ₅ and R ₆ has a waveform shifted by approximately λ / 4 phase from the resistance change of the MR elements R ₁ and R ₂ . Here, similarly, MR elements R ₅ and R ₆ are connected to three terminals (not shown), and when a voltage is applied to both ends, the output voltage E _A2 becomes the output E _A1 as shown in FIG. 14 (d). On the other hand, almost λ / 4
Waveforms out of phase can be obtained. When the outputs of the magnetic sensor 4 are two-phase outputs in this way, the respective outputs can be used for position detection and speed detection in addition to torque detection. Furthermore, since each output is a two-phase output, speed detection and phase detection information can be obtained more accurately on the load side and the motor side, respectively, according to the load state. Therefore, when the information on the desired side (load side or motor side) is already known, either one may have a two-phase output configuration as required.

FIG. 15 shows detection by the magnetic sensor 4 on the rotary drums 2, 2 '.
FIG. 3 is a structural diagram of the magnetic recording unit 3, 3 ′ in the circumferential direction of FIG.
Has a structure that substantially coincides with the circumferential direction of the rotary drums 2, 2 '. With such a structure, since the magnetic sensor 4 is arranged in the circumferential direction, an effect that the outer diameter of the torque detecting device can be reduced can be obtained.

In the above embodiments, the rotary drums 2 and 2'has been described as cup-shaped, but the effect is not changed even if they have a normal disc shape or a cylindrical shape. Further, the respective configurations are not limited to those, and the combination and the like can be freely set according to the specifications and purposes.

〔The invention's effect〕

INDUSTRIAL APPLICABILITY As described above, the present invention provides a drive-side rotary drum that is mounted on the drive-side of the rotary shaft, a load-side rotary drum that is mounted on the load-side of the rotary shaft, and a fine magnet on the surface of the drive-side rotary drum. Drive-side signal track formed by arranging, a load-side signal track formed by arranging fine magnets on the surface of the load-side rotating drum, and a drive-side provided so as to face the drive-side signal track A magnetic sensor having a magnetoresistive effect element on the load side and a magnetic sensor having a magnetoresistive effect element on the load side that is provided so as to face the signal track on the load side, and one of the both rotary drums is attached to a rotary shaft. Part and an extending part extending from the shaft mounting part so as to be closer to the other rotating drum, are formed in a cup shape. The magneto-resistive effect element on the driving side and the magneto-resistive effect element on the load side are formed so as to be carried on the same substrate by vapor deposition etching or the like, and the resistance values of both magneto-resistive elements are compared. A torque detection device is characterized in that the torque applied to the rotating shaft is detected.

According to the present invention having such a configuration, the following advantages can be expected.

(1). Either one of the two rotary drums is formed in a cup shape with a shaft mounting portion to be mounted on the rotary shaft and an extending portion extending from the shaft mounting portion so as to be closer to the other rotary drum. Since they are arranged close to each other, the magnetic recording of the fine magnets forming both signal tracks can be simultaneously formed by one magnetic recording head. For this reason, unlike the magnetic recording that is performed separately, the fine magnets that form both signal tracks do not have an error in the positional relationship with each other, and a high detection accuracy can be obtained.

(2). Since both magnetoresistive effect elements constituting the magnetic sensor can be arranged close to each other, the adjustment error at the time of mounting can be reduced, and the torque detecting device can be downsized.

(3). Since the drive-side magnetoresistive effect element and the load-side magnetoresistive effect element are formed so as to be carried on the same substrate by vapor deposition etching or the like, it is not necessary to form each magnetoresistive effect element on a separate substrate. Differently, it is not necessary to align the magnetoresistive elements, and a highly accurate torque detection device can be provided. Further, since both magnetoresistive effect elements are formed on the same substrate, the number of parts is reduced, and the attachment and adjustment to be opposed to both signal tracks is facilitated, and the cost is reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a torque detection device according to an embodiment of the present invention, FIG. 2 is a sectional view of FIG. 1, FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. The figure is the operation explanatory diagram, Fig.8, Fig.10
FIG. 11, FIG. 13, FIG. 13 and FIG. 15 are schematic cross-sectional views of a torque detection device according to another embodiment, FIG. 9 is an operation explanatory view of FIG. 8, FIG. 12 is FIG. Operation explanatory diagram according to FIG. 11,
FIG. 14 is a diagram for explaining the operation of FIG. 1 ... Axis, 2,2 '... Rotary drum, 3,3 ... Magnetic recording unit,
4 ... Magnetic sensor, 5, 5 '... Reference position signal.

Front page continuation (72) Inventor Kunio Miyashita 4026 Kuji-cho, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi Co., Ltd. (56) References JP 59-65738 (JP, A) JP 60-243532 ( JP, A) JP 61-187627 (JP, A) Actually developed 61-76338 (JP, U)

Claims (1)

[Claims] 1. A drive-side rotary drum mounted on the drive-side of a rotary shaft, a load-side rotary drum mounted on the load-side of the rotary shaft, and fine magnets arranged on the surface of the drive-side rotary drum. A drive-side signal track to be formed, a load-side signal track formed by arranging fine magnets on the surface of a load-side rotating drum, and a drive-side magnetoresistive effect provided so as to face the drive-side signal track. Element and a magnetic sensor having a load side magnetoresistive element provided so as to face the signal track on the load side, and one of the both rotary drums has a shaft mounting portion mounted on a rotary shaft and the shaft. A cup-like shape is formed with an extending portion that extends from the mounting portion so as to be closer to the other rotating drum, and the two signal tracks are provided at positions near the two rotating drums. The magneto-resistive effect element on the drive side and the magneto-resistive effect element on the load side are formed so as to be carried on the same substrate by vapor deposition etching or the like, and the resistance values of both magneto-resistive effect elements are compared and rotated. A torque detecting device characterized by detecting torque applied to a shaft.