JPH0381631A - Rotary sensor - Google Patents

Abstract

PURPOSE:To detect the rotational position and torque with simple structure at the same time and to obtain the high-sensitivity rotary sensor by providing a rotational positions sensor and a torque sensor which has high resolution on a rotary shaft in one body. CONSTITUTION:When torque is applied to the rotary shaft 1, it is transmitted to a magnetic strain medium 5, which varies in magnetic permeability. Then detection solenoid coils 8 and 8' vary in inductance and corresponding electric signals are led to a detecting circuit through leads 9 and 9' to detect the torque. The electric resistance values of magnetic resistance bodies 3 and 3' varies with the rotational position of the magnetic recording medium 4 according to the relative position relation between the magnetic resistance bodies 3 and 3' to obtain pulses of level corresponding to the rotational position and they are led to a detecting circuit through leads 10 and 10' to detect the position. The rotational position is differentiated with time to know the angular speed of the shaft 1 and the change state of the electric signals from a reference position is detected to know forward/backward rotation. A signal detection part is arranged nearby the intermediate part of the rotary shaft and sealed compactly to reduce the cost with a dust-proof and magnetic shied surface.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a rotation sensor that detects the rotational position (angular velocity) and torque of a rotating shaft of a motor, engine, or the like.

(Prior art) In recent years, with the development of factory automation equipment and information equipment, it has become difficult to control the rotational position and torque of the rotating shaft of the motor etc. with high precision in the motors etc. that are the rotational drive means of these equipments. For example, in recent lathes, in order to combine machining and shorten machining time,
Two rotating axes are installed to enable continuous double-sided machining.
There is a need for a highly accurate rotation control system that can move a workpiece from one rotating shaft to another without stopping rotation.

During such rotation control, in order to accurately move the workpiece according to predetermined machining conditions, the rotational position and rotational torque of the rotating shaft are detected, and the detection signal is sent to the control unit to electrically need to be controlled. In this case, the rotational position signal and rotational torque signal of the rotational shaft are detected by an optical rotational position sensor and a magnetic torque sensor that are respectively disposed on and off the rotational shaft.

(Problems to be Solved by the Invention) Conventionally, as the optical rotational position sensor and the magnetic torque sensor are arranged separately, the overall sensor structure becomes large and complicated. With water,
A sealing protection structure against oil, dust, etc. must also be provided separately, which increases complexity and increases manufacturing costs.

Incidentally, in recent years, as a sensor for detecting rotational position, a magnetic type sensor that detects rotational position by combining a magnetic recording medium and a magnetoresistive element has been developed (Nikkei Mechanical magazine 19
May 15, 1989 issue, p. 68).

Furthermore, as a sensor for detecting torque, a magnetostrictive type sensor that detects torque by combining a solenoid coil and a magnetostrictive medium has been developed (Japanese Patent Application Laid-open No. 206421/1983).

(Objective of the Invention) Considering the above-mentioned technical background, the present inventors believe that if a non-contact magnetic rotational position sensor and a torque sensor can be integrated into one on a rotating shaft, the rotational position and torque of the rotating shaft can be improved. This invention was completed by focusing on the fact that not only can both be detected simultaneously, but also that a rotation control sensor with a compact structure can be obtained at low cost. More specifically, - In order to obtain a non-contact rotation sensor that detects the rotational position and torque as electrical signals, a magnetoresistive element and a magnetic recording medium are used to detect the rotational position, and a magnetic recording medium is used to detect the torque. It uses a solenoid coil and a magnetostrictive medium.

That is, an object of the present invention is to provide a rotation sensor for controlling the rotation shaft of a motor, engine, etc. by integrating a high-resolution rotation position sensor and a torque sensor on the rotation shaft, thereby controlling the rotation position with a simple structure. The object of the present invention is to provide a rotation sensor that can simultaneously detect torque and torque, has excellent environmental resistance, and has high sensitivity performance.

(Means for Solving the Problems) In order to achieve the above-mentioned objects, the present invention has a magnetostrictive film made of a soft magnetic thin film whose magnetic permeability changes depending on the magnitude of the rotational torque, on the outer peripheral surface of the rotating shaft. A magnetic recording medium made of a hard magnetic thin film divided and magnetized at equal intervals in the circumferential direction is provided, and this rotating shaft is rotatably held within an outer cylinder support frame via a bolt. The present invention is characterized in that a solenoid coil for torque detection and a magnetic resistance body for rotational position detection are disposed at positions corresponding to the magnetostrictive medium and the magnetic recording medium on the cylinder support frame, respectively.

(For 1 unit) According to the rotation sensor according to the invention described in claim 1, when torque is applied to the rotating shaft, the magnetic permeability of the magnetic medium changes, and the change in the generated magnetic flux caused by this is detected by the torque detection solenoid. By detecting this, the torque of the rotating shaft can be detected. Further, the resistance value of the magnetoresistive element changes depending on the relative positional relationship in the rotational direction with respect to the magnetic recording medium. In other words, as the rotational position of the rotating shaft with respect to the outer cylinder support frame changes, the resistance value of the magnetic resistance body also changes. Therefore, by detecting this resistance value, the rotational position of the rotating shaft can be detected. It goes without saying that the frj speed can be obtained by time-differentiating the rotational position signal.

As described above, in the invention according to claim 1, on the rotating shaft,
Since a rotational position detection means consisting of a combination of a magnetic recording medium and a magnetoresistive element and a torque detection means consisting of a combination of a magnetostrictive medium and a solenoid coil are provided, both the rotational position and torque of the rotating shaft can be detected in one piece. It can be detected with a rotation sensor.

Further, in the invention as claimed in claim 2, since the solenoid coil for torque detection and the magnetic resistance body for rotational position detection are fixed within the outer cylinder support frame, and this outer cylinder support frame is formed of a magnetic shielding material, the outer cylinder support frame not only prevents water, oil, dust, etc. from entering the inside, but also functions as a magnetic shielding means for the torque detection solenoid coil and the rotational position detection magnetic resistance body. Thereby, the sensitivity of the rotation sensor can be improved by preventing the influence of magnetic disturbance on the sensor detection section.

(Example) An embodiment of the present invention will be described below based on the drawings.

FIG. 1 is a sectional view showing the structure of a rotation sensor according to this embodiment. In this figure, 1 is a rotating shaft that transmits the rotational force of a drive motor (not shown) to the load side, and the rotating shaft 1
is rotatably held in an outer cylinder support frame 2 made of a magnetically shielding material such as steel via k receivers 6, 6-. , a magnetostrictive medium 5 is inserted and fixed in an IC (IC). As shown in FIG. 2, this magnetostrictive medium 5 has a region A and a region B in which the directions of magnetic anisotropy are different from each other.

Further, as shown in FIG. 3, a cylindrical base 7 made of non-magnetic stainless steel is fitted and fixed in a portion of the rotating shaft 1 near the magnetostrictive medium 5. As shown in FIG. The outer peripheral surface of this base 7 is made of Ni-F with a thickness of 20 μm that has magnetic shielding properties.
The e-alloy plating film 11 is broken, and furthermore,
A magnetic recording medium 4 made of predetermined cotton is placed along the circumferential direction of the base 7.
It is magnetized at intervals of /2π radians, that is, divided into 360.

The magnetic recording medium 4 is made of a hard magnetic thin film of about 200 μm thick made of permalloy and iron oxide, and its magnetization pitch is set to about 220 μm.

On the other hand, on the inner surface of the outer cylinder support frame 2, a portion corresponding to the magnetic medium 5 is provided with solenoid coils 8, 8' for detecting torque.
is provided. This solenoid coil 8.8' is arranged so as to intersect with the generated magnetism from regions A and B of the magnetostrictive medium 5.

Furthermore, a magnetoresistive element 3.3- for the rotational position horizontal position, which functions as a magnetoresistive sensor, is provided in a portion of the inner surface of the foreign support frame 2 that corresponds to the magnetic recording medium 4. The magnetic resistance elements 3 and 3' are arranged at positions displaced from each other by 180° in the circumferential direction of the outer cylinder support frame 2 in order to compensate as much as possible for fluctuations in output current due to rotational wobbling of the rotating shaft 1. There is.

Here, the structure of the magnetoresistive elements 3 and 3' is formed by forming an N-1-Fe alloy thin film on a glass substrate.
, 3゛ two-phase outputs φA, φA' and φB.

φB' is a phase difference of 90 in the rotation direction of the magnetic recording medium 4.
° is set to have. The outputs obtained from the rotational position detecting magnetic resistor 3.3' and the torque detecting solenoid coils 8, 8' are sent to a detection circuit (not shown) via lead wires 10.10" and 9, 9', respectively. This detection circuit consists of a manual conversion section, a bridge circuit section, and an output circuit section.
It has a differentiation circuit section for detecting angular velocity if necessary.

Next, the detection operation of this first row of rotation sensors will be explained.

Now, when the drive motor rotates the rotating shaft 1 and torque is applied to it, this torque rotates! The torque is transmitted to the magnetostrictive medium 5 of lhl, and its permeability changes depending on the magnitude of the torque. When the magnetic permeability of the magnetostrictive medium 5 changes, the inductance of the solenoid coil 8.8' that detects this changes, and an electric signal corresponding to the change is output. This electrical signal is input to the detection circuit via the lead wire 9.9', whereby the torque applied to the rotating shaft 1 is detected.

On the other hand, the rotational position of the magnetic recording medium 4 is
The electrical resistance value of the magnetoresistive element 3.3' is changed depending on the relative positional relationship with the magnetoresistive element 3.3'. Therefore, the magnetoresistive element 3.3' outputs an electric signal as a pulse having a magnitude corresponding to the rotational position of the magnetic recording medium 4, that is, the rotating shaft 1. This signal is inputted to the detection circuit via the lead wire 10.degree. 10', whereby the rotational position of the rotary shaft 1 is detected. moreover,
By time-differentiating this rotational position using a differentiating circuit, the 111 speed of the rotating shaft 1 is detected. In addition, when the rotation direction of the rotating shaft 1 is determined by I'll if necessary, the rotation direction is determined by detecting the state of change in the electrical signal from the reference position at the circumference of the rotating shaft 1. A diversion/reversal of 1l11 is determined.

As described above, according to this embodiment, in terms of functionality, the rotational position, angular velocity, torque, and rotational direction of the rotating shaft 1 can be detected by one rotation sensor.
It is fully compatible with the complex machining and automation of recent lathes, etc. In addition, in terms of structure, the magnetostrictive medium 5° magnetic recording medium 4, which is the signal detection part, is arranged near the middle of the rotating shaft 1, so it has a sealed structure to prevent the intrusion of water, oil, dust, etc. can be printed compactly. In addition, the outer tube support frame 2 functions as a magnetic shielding member for both the magnetostrictive medium 5 and the magnetic recording medium 4, which simplifies the magnetic shielding structure and reduces manufacturing costs. At the same time, it is possible to improve the ability to double the sensor output against magnetic disturbance.

(Effects of the Invention) As explained above, according to the invention as set forth in claim 1, since the rotational position detection means and the torque detection means are integrally incorporated in the rotation shaft "2" in the outer cylinder support frame, Both the rotational position and the torque of the rotating shaft can be detected with one rotation sensor, and the advantage is that manufacturing is easy and the overall structure of the sensor can be made compact.

Further, according to the invention as claimed in claim 2, the outer cylinder support frame functions as a shield member against disturbance magnetic field, etc., so that it is possible to prevent dust and the like from entering the inside of the sensor and improve the reliability of sensor detection sensitivity. In addition, it is possible to simplify the shielding structure against the external environment and reduce manufacturing costs.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing a schematic configuration of a rotation sensor according to the present invention, Fig. 2 is a perspective view showing a torque detection section in the rotation sensor using a combination of a magnetostrictive medium and a solenoid coil, and Fig. 3 is a rotation sensor according to the present invention. FIG. 2 is a perspective view showing a rotational position detection section in a sensor that is a combination of a magnetic recording medium and a magnetoresistive element. 1...Rotating shaft 2...Outer cylinder support frame 3.3'...Magnetic resistance body 4...Magnetic recording medium 5...Magnetostrictive medium 6...Bearing' 7...Cylindrical shape Base 8.8'... Solenoid coil patent creator Hitachi Powder Metallurgy Co., Ltd.

Claims (1)

[Scope of Claims] 1. A magnetostrictive medium made of a soft magnetic thin film whose magnetic permeability changes depending on the magnitude of the rotational torque, and a hard magnetic medium magnetized at equal intervals in the circumferential direction on the outer peripheral surface of the rotating shaft. A magnetic recording medium made of a thin film is provided, the rotary shaft is rotatably held within an outer cylinder support frame via a bearing, and the rotary shaft is rotatably held in the outer cylinder support frame at a position corresponding to the magnetostrictive medium and the magnetic recording medium. A rotation sensor characterized in that a solenoid coil for torque detection and a magnetic resistance element for rotational position detection are respectively provided. 2. The rotation sensor according to claim 1, wherein the outer tube support frame is made of a magnetically shielding material.