JPH01173845A - Torque measuring instrument - Google Patents

Abstract

PURPOSE:To detect excellently torque which varies owing to temperature variation, a secular change, etc., irrelevantly to whether or not a torque load is large by compensating the exciting voltage of a coil for torque detection as the exciting current of the correcting coil corresponding to a magnetic anisotropic part for correction which is not affected by a torque signal is controlled. CONSTITUTION:A magnetic anisotropic part 12 for torque detection which is given magnetic anisotropy in the direction and at the angle of an axis of rotation is arranged on the surface layer of a shaft 11 for torque transmission. A magnetic anisotropic part 14 for correction which is given magnetic anisotropy in parallel to the axis of rotation is arranged on the surface of the shaft nearby the anisotropic part 12. A detecting coil 20 and a correcting coil 22 are arranged at the peripheries of those anisotropic parts 12 and 14, a CPU is connected to the coil 20 through an A/D converter, and a CPU 40 is connected to the coil 22 through an A/D converter 36. Then the CPU 40 controls a power source 26 through D/A converters 42 and 46 so that measurement data becomes equal to a reference value from a reference value setting device 47 connected to the CPU 40.

Description

[Detailed description of the invention] Industrial applications TECHNICAL FIELD The present invention relates to a torque measuring device, particularly for engines.

The present invention relates to a torque measuring device that can non-contactly measure the torque of motors, industrial machine drive shafts, etc.

Prior Art A conventional torque measuring device of this type is disclosed in Japanese Patent No. 1693.
26j'3 specification collection. As shown in FIG. 5, this is a knurling section formed on the outer periphery of a shaft 1 having ferromagnetic properties and magnetostrictive properties and inclined in opposite directions at an angle of 45 degrees with the direction of the axis of rotation of this shaft 1. 2 and 3, and an excitation coil 4 and detection coils 5 and 6 are arranged around the outer periphery of each knurling part 2 and 3, respectively.

According to such a configuration, magnetic anisotropy is imparted by the knurling portion 2.3, and changes in magnetic permeability in each of the knurling portions 2, 3 based on the transmitted torque are detected by the detection coil 5.6. At this time, since the knurling parts 2 and 3 are inclined in opposite directions, when a compressive force is applied in one knurling direction, a tensile force is applied in the other knurling direction. Therefore, as shown in FIG. 6, the detected voltage 7 of one of the coils 5.6 increases as the torque increases, while the detected voltage 8 of the other coil decreases.

Here, when the difference between the detection voltage 7 of one coil and the detection voltage 8 of the other coil is taken and combined, a torque detection voltage 9 showing only a change in torque is obtained as shown in FIG.

In addition, as another conventional torque detection device,
There is one shown in Japanese Patent No. 166827. In this case, instead of the knurling part 2.3 in FIG. 5, amorphous ferromagnetic layers tilted in opposite directions are bonded and
A magnetically anisotropic portion is formed on the surface of the rotating shaft by plating or other methods.

If such a magnetic anisotropic portion is formed, torque can be measured even if a shaft that does not have ferromagnetism is used.

Problems to be Solved by the Invention However, in such conventional devices, the level of the detection voltage 7.8 changes due to temperature changes and changes over time, and the slope also tends to change with this level change. be. This is due to changes in the magnetism (magnetic permeability, magnetostriction) of shaft 1, changes in the electrical characteristics of each coil 4.5.6, changes in the a-loss of shaft 1, and changes in the elastic modulus. This is for the purpose of As a result, the slope of the torque detection voltage 9 in Fig. 7 changes, the measurement sensitivity changes, and the zero point of the detection voltage 9 (output value when torque is zero) changes, causing an error in the torque measurement value. There are problems that arise.

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems and prevent errors from occurring in torque measurement values due to changes in sensitivity and zero point as described above.

Means for Solving the Problems In order to solve the above problems, the present invention provides a magnetic anisotropic portion for torque detection, which is provided with magnetic anisotropy at an angle with the direction of the rotational axis of the torque transmission shaft. , a correction magnetic anisotropy section having magnetic anisotropy imparted to the outer peripheral surface of the sleeve in the vicinity of the torque detection magnetic anisotropy section in a direction parallel to the rotational axis of the shaft, and the torque detection magnetic anisotropy section. A detection coil and a correction coil are provided around the magnetic anisotropy section and the correction magnetic anisotropy section, respectively, and an electric current is applied to the correction coil so that the measurement data of the correction coil becomes equal to a certain reference value. and means for controlling the excitation voltage applied to the detection coil in response to the control of the excitation voltage for the correction coil.

According to such a configuration, the control means controls the excitation voltage for the correction coil so that the measurement data of the correction coil becomes equal to a certain reference value, and in conjunction with this, the excitation voltage for the detection coil is controlled. To control the excited CIITs pressure,
Detection sensitivity is maintained at a constant level. Therefore, the slope of the detection voltage and the output level under a constant torque load are kept constant, and changes in torque detection sensitivity are prevented. Here, since the correction magnetic anisotropy section is formed in a direction parallel to the axis of the shaft, the output of the correction coil is not affected by the torque acting on the shaft. Therefore, the measurement data of the correction coil is always controlled to a constant value, regardless of the presence or absence of torque load on the shaft, its magnitude, secular changes in the magnetic characteristics of the shaft, or temperature changes, so the sensitivity of the detection coil remains at a constant level. maintained.

Embodiment In FIG. 2, reference numeral 11 denotes a torque transmission shaft, which is used, for example, to transmit the output of an engine to a working device. A magnetic anisotropic portion 12 for torque detection is provided on the outer peripheral surface of the shaft 11 and is provided with a magnetic anisotropy having an angle of 20 to 60 degrees, preferably 45 degrees, with respect to the direction of the axis of the shaft 11. ing. As described above, the torque detecting magnetic anisotropic portion 12 can be formed, for example, by knurling the outer peripheral surface of the shaft 11, or by bonding or plating an amorphous ferromagnetic layer on the surface of the shaft 11. It can also be formed by

A correction magnetic anisotropy section 14 is provided on the outer peripheral surface of the shaft 11 in the vicinity of the torque detection magnetic anisotropy section 12 . This correction magnetic anisotropy section 14 is provided with magnetic anisotropy in a direction parallel to the axis of the shaft 11, and is processed by knurling or an amorphous ferromagnetic layer similar to the torque detection magnetic anisotropy section 12. It is constructed by bonding etc.

An excitation coil 16 is arranged around both magnetic anisotropic parts 12 and 14.
, 17 are arranged respectively. Furthermore, a detection coil 20 corresponding to the torque detection magnetic anisotropy section 12 and a correction coil 22 corresponding to the correction magnetic anisotropy section 14 are provided on the outer periphery of both excitation coils 16 and 17, respectively. ing. 24 is a core, which is made of ferromagnetic material and constitutes a magnetic flux core, and each coil 16, 17, 20
．． It is used as a casing for accommodating 22.

FIG. 1 shows the overall configuration of this device including an electronic circuit. In the figure, 25 is an oscillator, and this oscillator 25 has:
An AC power source 26 composed of a power amplifier is connected. The excitation coils 16 , 17 are connected in series to the power supply 26 . The detection coil 20 and the correction coil 22 each include a rectifier 29, 28, a filter 33, 32 composed of a resistor and a capacitor, and an AD
It is connected to the CPU 40 via converters 37 and 36.

The CPU 40 is connected to an electric fi cutoff signal 41 for cutting off the output of the power supply 26 along with a DA converter 42 . In addition, the CPU 40 has a power supply 26
A power supply control signal line 44 for adjusting the amplification factor of the power amplifier constituting the power amplifier and controlling its output is connected together with a DA converter 46. 47 is a reference price setting device, which can be set digitally or by software using the CPU's internal memory. Further, a timing circuit 48 is connected to CI) U3O, and generates the operation timing for water control. 49 is a torque signal output terminal. 50.
Reference numeral 52 denotes a manual switch, which is used to correct the above-mentioned errors at any time regardless of the operation timing of this circuit.

Next, the operation based on the above configuration will be explained. When the power supply 26 is turned on, an output voltage appears in the detection coil 20 and the correction coil 22, and each voltage becomes v and S at the output side of the AD converters 37 and 36, that is, on the input side of the CPU 40.
The value is .

For these values V and S, the CPU 40 corrects zero point errors that occur in electronic circuits due to temperature changes and aging.
This is done as follows.

That is, first, the power is
I! The output of A26 is cut off. Then both excitation coils 1
Since the excitation TFI voltages 6 and 17 become zero, the output voltages of the detection coil 20 and the correction coil 22 should also become zero correspondingly. Therefore, at this time, the outputs of both AD converters 37 and 36 are values other than zero, for example ■=ε
, S=δ, this is based on some kind of error. Therefore, the CPU 40 calculates v' =
Arithmetic processing is performed so that v-ε, s'=s-δ. As a result, when the power is cut off, V'=s'=o, and the zero point correction of the electronic circuit itself is completed.

At that time, the cutoff of the power supply 26 is canceled, but the above formula v'=
The arithmetic functions expressed by v-ε, s' = s-δ are retained as they are.

Next, if this continues, instructions 1f after power supply 26 release (return)
iK (V'-8') does not necessarily indicate zero when the torque is zero, but when the torque is known to be completely zero (for example, when adjusting the hinge for the first time or when the engine is running) When the manual switch 50 for manual zero point correction is operated, the signal is taken into the CPU 40, and the torque instruction 1a-B of the debris is reduced or reduced to zero the torque instruction value. This B is the CPU until the next manual zero point correction.
stored in the memory. From now on, the indicated value is k (V'-8'
)-8 is used.

Next, sensitivity correction is performed. That is, when the characteristics of the device change due to temperature changes, both signals v' and s' fluctuate up and down as shown by the two-dot chain line in FIG. 3 (zero point correction value 8 is omitted). Moreover, the slope of the calibration value V' based on the signal from the detection coil 20 also changes. As a result, the slope of the torque signal T+-, denoted K (V'-8'), changes and the measurement sensitivity changes, causing an error.

Therefore, the output level of the power supply 26 is increased or decreased by the power supply control signal line 44, and the excitation voltages of both excitation coils 16 and 17 are simultaneously lowered, so that the calibration value S' based on the signal from the correction coil 22 is adjusted to the reference fh. S'
-Es = O. By doing this, the values v' and s' indicated by the two-dot chain lines in FIG.
is corrected to the state shown by the solid line, the slope of the calibration value V' also becomes a predetermined state, and the torque measurement sensitivity is corrected.

Note that, on the contrary, by changing the reference setting value Es, the measurement sensitivity of the present V device can be varied in various ways, thereby making it possible to provide a wide variety of measurement ranges.

The above-mentioned stretch zero point correction and sensitivity correction are carried out by the timing circuit 4.
8, the operations are performed in this order at a fixed timing. That is, for example, as shown in Fig. 4, one cycle is one minute, and zero point correction is performed in the first 50 milliseconds.
During the remaining time, the torque output value is adjusted in parallel while sensitivity correction is constantly performed, that is, many times, and such a cycle is repeatedly executed. Airo can also perform zero point correction, sensitivity correction, and output performance at different timings.

Note that while the zero point correction is being performed, the blue torque signal from the previous cycle is held and output from the terminal 49.

Next, a case in which manual correction is performed using the manual switch 52 for sensitivity correction will be described. For example, when the production of this device is completed, the rated torque is applied to the shaft 11 using a lever and a weight, and the reference 11! is applied so that the indicated value at that time matches the rated value. All you have to do is adjust the i setting device 47.

Effects of the Invention As described above, according to the present invention, in addition to controlling the excitation voltage for the correction coil corresponding to the correction magnetic anisotropic part that is not affected by the torque signal, the excitation voltage for the torque detection coil is controlled. The torque detection sensitivity is corrected by controlling the excitation voltage of the motor, and the electronic circuit zero correction and output value zero correction are performed by shutting off the power supply. This makes it possible to satisfactorily correct torque detection sensitivity that fluctuates based on temperature changes, aging, etc., and enables highly accurate torque detection.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of the torque measuring device of the present invention;
Fig. 2 is a detailed diagram around the axis in Fig. 1, Fig. 3 is a graph illustrating the detected voltage, Fig. 4 is an operation timing diagram of the circuit shown in Fig. 1, and Fig. 5 is a diagram of the conventional torque measuring device. In the schematic diagram, FIG. 6 is a graph showing the detected voltage in the device of FIG. 5, and FIG. 7 is a graph showing the torque signal based on FIG. 6. 11... Axis, 12... Magnetic anisotropic part for torque detection,
14... Magnetic anisotropy part for correction, 16.17... Excitation coil, 20... Detection coil, 22... Correction coil, 26... 71B, 40... CpU, 47...・Reference value setting device. Agent I Hiroshi MorimotoFigure 2Figure 3Figure 41

Claims (1)

[Scope of Claims] 1. A magnetic anisotropic portion for torque detection in which a shaft surface layer of a torque transmission shaft is provided with magnetic anisotropy at an angle with the direction of the axis of rotation; a correction magnetic anisotropy section provided with magnetic anisotropy in a direction parallel to the rotational axis in a shaft surface layer near the orthotropic section; the torque detection magnetic anisotropy section and the correction magnetic anisotropy section; A detection coil and a correction coil are respectively provided around the genital area, and the excitation voltage applied to the correction coil is controlled so that the measurement data of the correction coil is equal to a certain reference value, and the correction coil is a means for controlling an excitation voltage applied to the detection coil in response to control of an excitation voltage for the detection coil. 2. A detection excitation coil is provided corresponding to the detection coil, and a correction excitation coil is provided corresponding to the correction coil, and the detection and correction excitation coils are connected in series and connected to a power source. A torque measuring device according to claim 1. 3. The torque measuring device according to claim 2, wherein the control means is capable of controlling the output of the power source. 4. means for cutting off the output of the power supply at an appropriate timing during torque measurement; means for obtaining measurement data of the detection coil and the correction coil when the power output is cut off; Claim 2, further comprising means for subtracting the measurement data of the detection coil and the correction coil from the measurement data of the detection coil and the correction coil at the time of power cutoff to calibrate the measurement data. The torque measuring device according to item 3. 5. The torque measuring device according to claim 4, wherein the control means is configured to perform control so that the calibration value of the measurement data of the correction coil becomes equal to the reference value. 6. The torque measuring device according to any one of claims 1 to 5, characterized by having a reference value setting device capable of setting a reference value. 7. Means for executing at regular timing a process of calibrating the measurement data of the detection coil and the correction coil, and a process of controlling the output of the power supply so that the calibration value of the measurement data of the correction coil becomes equal to the reference value. The torque measuring device according to claim 5 or 6, characterized in that the torque measuring device has: 8. Claim 7, characterized by having a manual switch that allows at least one of the two processes to be executed at any time by manual operation, regardless of the fixed timing. torque measuring device. 9. Any one of claims 4 to 8, characterized by having a torque value output terminal that outputs a value obtained by multiplying the difference between the calibration values of the measurement data of the detection coil and the correction coil by a coefficient. The torque measuring device described in .