JPH02296122A - Stress measuring method using magnetostruction type stress sensor - Google Patents

Abstract

PURPOSE:To make it possible to measure stress accurately by dividing the detected value of a magnetic sensor for detecting stress by the detected value of a magnetic sensor for detecting a gap. CONSTITUTION:The high frequency signal from a transmitter 11 acts on both magnetic sensors 1 and 10. The detected signals from the sensors 1 and 10 are rectified in a lock-in amplifier 12 and an amplifier rectifier 13. Outputs V1 and V2 from the sensors are inputted into an operator 14. In the operator 14, the operation of the outputs V1/V2 is performed, and a measured value F(tau) of the stress is obtained. In this way, the accurate stress measurement can be performed.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a magnetostrictive stress sensor using an excitation type magnetic sensor, in which the stress J is
The present invention relates to a method for performing the l-determination.

[Conventional technology]

As this type of conventional technology, for example, Japanese Patent Application Laid-open No.
As shown in Japanese Patent No. 4230, a shaft torque measuring device is known. This eliminates air gap fluctuations between the shaft and the torque measuring device by multiplying the magnetic heads of the torque detector in the circumferential direction of the shaft and averaging the output of each head.

[Problem to be solved by the invention]

For example, in the conventional torque measuring device mentioned above, air gap fluctuations between the shaft and the magnetic sensor are measured by arranging a plurality of magnetic sensors in the rotational direction of the shaft and taking the average of their outputs as the torque value. There is a problem in that a plurality of measurement systems are required, and it takes time and effort to assemble the measurement system.

In addition, if only one sensor was used, it would take time and effort to adjust the alignment, and accuracy could not be expected.

The present invention has been made in view of the above, and an object of the present invention is to provide a stress measurement method using a magnetostrictive stress sensor that can accurately measure stress without being affected by gap fluctuations between the magnetostrictive stress sensor and the object to be measured. It is something to do.

[Means to solve the problem]

In order to achieve the above object, the stress n1 determination method using the magnetostrictive stress sensor according to the present invention is based on the detection value { , from a gap detection magnetic sensor that measures the gap between the stress detection magnetic sensor and the measurement object, which is installed at a position where the magnetic properties do not change due to the stress of the object to be measured. is divided by the detected value V2, and the result is taken as the stress measurement value.

[For production]

By dividing the detected value of the magnetic sensor for stress detection by the detected value of the magnetic sensor for gap detection, it is possible to calculate Measurement errors are corrected.

〔Example〕

Embodiments of the present invention will be described based on the drawings.

In the figure, reference numeral 1 denotes a stress detection magnetic sensor for measuring the stress acting on the object 2 by detecting changes in the magnetic properties of the object 2.
The excitation system has an excitation coil 4 wound around both legs of an excitation core 3 formed in a U-shape, and a detection coil 6 wound around both legs of a detection core 5 formed in a U-shape. The detection system is arranged at a certain angle, and by transmitting a predetermined high frequency signal from an oscillator to this magnetic sensor 1, the stress acting on the object 2 facing the magnetic sensor 1 is magnetically This signal is detected as a change in characteristics, and is input to a stress calculation circuit via a rectifier or the like, where the stress is calculated.

The configuration described above is almost the same as a conventional magnetostrictive stress sensor, and according to this configuration, the stress detection value is
Since it changes depending on the gap variation between and the measured object 2,
Conventionally, multiple detection signals are averaged to obtain a torque value.

The magnetostrictive stress sensor according to the present invention is capable of accurately determining all stresses unaffected by the above-mentioned gear fluctuations.

That is, as shown in FIG. 1, the excitation core 3 of the excitation system of the magnetic sensor 1 for stress detection has a gap for detecting the gap X between the magnetic sensor 1 for stress detection and the object to be measured 2. A magnetic sensor 10 for determining the gap n1, which is formed by winding a detection coil 9, is provided in addition to the magnetic sensor 1 for stress detection.

In the above configuration, the functions of the sensor output V of the magnetic sensor 1 for stress detection and the sensor output V2 of the magnetic sensor 10 for gap detection with respect to gap fluctuations have the same form as follows.

However, f(r), the stress acting on he n1 constant 8, Vo
: Output X when the magnetic sensor 1 for stress detection is in contact with the object to be measured 8 (gap - ○): Gap a, b: Constant determined by the positional relationship of the two magnetic sensors 1 and 10 The above gap detection Sensor output v2 of the magnetic sensor 10 of
When the gap X becomes larger than a certain value, it does not change with respect to changes in the magnetic properties due to the stress of the object to be measured 2.

From this, in the magnetic sensor 1 for stress detection, the excitation core 3 of the excitation system to which the magnetic sensor 10 for gap detection is attached is relative to the detection core 5 of the detection system in the gap X direction. , and both denominators of equation (1) above, x
Set so that 10a and x+b are equal.

When the stress of the object to be measured 2 is measured with the magnetic sensor 1 for stress detection in the above state, the magnetic sensor 1 for stress detection
The sensor output v1 of the gap detection magnetic sensor 10
By dividing by the sensor output V2, a constant cuff TPJ value F(τ) that is not affected by gap fluctuations can be obtained.

FIG. 2 shows the operation for obtaining the stress measurement value F(τ), in which a high frequency signal from the transmitter 11 acts on both magnetic sensors 1 and 10, and a detection signal from both magnetic sensors 1 and 10 is generated. are rectified by the lock-in amplifier 12 and the rectifier 13 to become the respective sensor outputs V, , V2, which are input to the calculator 14, where V, /V2 are calculated and the stress measurement value F(τ) is obtained. is obtained.

SNCM22 with magnetic sensor 1 set as above
The stress measurement value F (τ) when measuring the stress of 0H (nickel chrome titanium steel) is shown in Fig. 3, and F
The rate of change in stress σ (%) with respect to the gap X of (τ) is:
It becomes constant when the gap X exceeds 0.25 ■l.

In addition, the gap X was changed stepwise from 0.5 mm to 2.0 mm, and at each gap! 111 and the stress measurement value F(τ) when the stress is changed is the fourth
As shown in the figure, even if the gap X changed, the measured value did not change.

From the results shown in FIGS. 3 and 4 above, it can be seen that stress measurement is performed without being affected by gap X fluctuations.

Note that in the above embodiment, the magnetic sensor 10 for gap detection
An example has been shown in which the gap detection coil 9 is wound around the excitation core which is a part of the component of the magnetic sensor 1 for stress detection. The gap detection coil 9 may be wound around a separate member from the magnetic sensor 1. In this case, the above member is fixed in position with respect to the magnetic sensor 1 for detecting stress in the gap X direction.

〔Effect of the invention〕

According to the present invention, it is possible to carry out accurate chemical coverage unaffected by variations in the distance (gap) between the magnetostrictive stress sensor and the object to be measured.

[Brief explanation of drawings]

The drawings show embodiments of the present invention; FIG. 1 is a schematic diagram for explaining the configuration, FIG. 2 is a diagram for explaining the operation, and FIGS. 3 and 4 are diagrams showing measurement results. Reference numeral 1 denotes a magnetic sensor for stress detection; 2 denotes a constant object tP1; 9 denotes a gap detection coil; and 10 denotes a magnetic sensor for gap measurement.

Claims (1)

[Claims] The detected value V_1 when the magnetic sensor 1 for stress detection consisting of an excitation system and a detection system is opposed to the object to be measured 2 does not change due to the change in magnetic properties due to the stress of the object to be measured 2 at this time. The result is divided by the detected value V_2 from the gap detection magnetic sensor 10 which is installed at a position to measure the gap between the stress detection magnetic sensor 1 and the object to be measured, and the result is the stress measurement value F(τ). A method for measuring stress using a magnetostrictive stress sensor, characterized in that: