US-12618693-B2 - Multi-rotation angle detection device

US12618693B2US 12618693 B2US12618693 B2US 12618693B2US-12618693-B2

Abstract

A multiturn angle detection device generates the multiturn absolute angle detection value of a rotating body. The multiturn angle detection device includes: a segment counter; a precision absolute angle detector; and an arithmetic device to generate the multiturn absolute angle detection value by combining the outputs of the segment counter and the precision absolute angle detector with each other. The segment counter includes: a single power generation sensor; a magnetic field generation source; a sensor element; and a nonvolatile memory to store a count value. The magnetic field generation source applies a k-cycle alternating magnetic field (wherein k is an integer not smaller than 3) per each turn of the rotating body axially of a magnetic wire. The arithmetic device uses the count value stored in the nonvolatile memory as it is, and combines the count value with the absolute angle detection value of the precision absolute angle detector.

Inventors

Akihiko Houda
Masayuki Someya

Assignees

ORIENTAL MOTOR CO., LTD.

Dates

Publication Date: 20260505
Application Date: 20231011
Priority Date: 20221025

Claims (6)

1 . A multiturn angle detection device to generate a multiturn absolute angle detection value of a rotating body that is rotated about a rotation axis, the multiturn angle detection device comprising: a segment counter to generate a count value according to the rotation of the rotating body by counting segments defined by dividing a single-turn cycle of the rotating body in an angular range over a single turn of the rotating body; a precision absolute angle detector, operative with external electric power supply, to generate an absolute angle detection value within the single-turn cycle of the rotating body at a resolution higher than the segments; and an arithmetic device, operative with the external electric power supply, to generate the multiturn absolute angle detection value of the rotating body by combining the count value of the segment counter with the absolute angle detection value of the precision absolute angle detector; wherein the segment counter includes a single power generation sensor, a magnetic field generation source to be rotated together with the rotating body about the rotation axis, a sensor element different from the power generation sensor, and a nonvolatile memory to store the count value; wherein the power generation sensor includes a magnetic wire that exhibits a large Barkhausen effect, and a coil wound around the magnetic wire, and generates a voltage pulse according to a magnetic field change occurring due to the rotation of the magnetic field generation source; wherein the magnetic field generation source applies a k-cycle alternating magnetic field (wherein k is an integer not smaller than 3) per each turn of the rotating body axially of the magnetic wire; wherein the segment counter is operative with an energy of the voltage pulse generated by the power generation sensor without receiving the external electric power supply, and is to detect a rotation direction and a rotational position of the rotating body by using the voltage pulse generated by the power generation sensor and an output signal of the sensor element to update the count value, and to store the updated count value in the nonvolatile memory; wherein the arithmetic device uses the count value stored in the nonvolatile memory as it is when receiving the external electric power supply, and generates the multiturn absolute angle detection value of the rotating body by combining the count value of the segment counter with the absolute angle detection value of the precision absolute angle detector.
2 . The multiturn angle detection device according to claim 1 , wherein the magnetic field generation source includes k magnets arranged on a circle defined about the rotation axis with their magnetic poles of the same polarity to be opposed to the power generation sensor, wherein the magnetic wire of the power generation sensor is disposed parallel to a tangential line of the circle, wherein the power generation sensor includes a first magnetic flux conducting piece and a second magnetic flux conducting piece respectively magnetically coupled to opposite end portions of the magnetic wire, wherein the magnetic poles are sequentially moved closer to the first magnetic flux conducting piece and the second magnetic flux conducting piece, as the magnetic field generation source is rotated, wherein the power generation sensor generates a negative voltage pulse in a first state in which a magnetic flux from any one of the magnetic poles of the magnetic field generation source is conducted through the first magnetic flux conducting piece, and generates a positive voltage pulse in a second state in which the magnetic flux from the magnetic field generation source is conducted through the second magnetic flux conducting piece.
3 . The multiturn angle detection device according to claim 1 , wherein the sensor element detects whether or not any one of the magnetic poles of the magnetic field generation source is present at a position opposed to a middle portion of the power generation sensor, and boundaries between the segments each define an angular position such that the one magnetic pole is opposed to the middle portion of the power generation sensor.
4 . The multiturn angle detection device according to claim 1 , wherein the magnetic field generation source includes k pairs of magnetic poles disposed on a circle defined about the rotation axis with their N-poles and S-poles alternately arranged.
5 . The multiturn angle detection device according to claim 4 , wherein the magnetic wire of the power generation sensor is located on a tangential line of a circle defined about the rotation axis with its middle point located at a contact point on the tangential line.
6 . The multiturn angle detection device according to claim 4 , wherein the sensor element detects a polarity of any one of the magnetic poles opposed to a middle portion of the power generation sensor, and boundaries between the segments each define an angular position such that one of the N-poles and the S-poles of the magnetic pole pairs is opposed to the middle portion of the power generation sensor.

Description

RELATED APPLICATION This application claims the benefit of priority to Japanese Patent Application No. 2022-170648, filed on Oct. 25, 2022, the disclosure of which is entirely incorporated herein by reference. TECHNICAL FIELD The present invention relates to a multiturn angle detection device employing a power generation sensor. More specifically, the present invention relates to a device that detects a multiturn absolute angle over a single turn by combining the count value of a segment counter employing the power generation sensor with an angle detection value obtained: n angle detector capable of precisely detecting an absolute angle based on a single turn cycle. BACKGROUND ART Magnetic wires having a large Barkhausen effect (large Barkhausen jump) are known in the name of Wiegand wire or pulse wire. Such a magnetic wire includes a core portion, and a shell portion provided around the core portion. One of the core portion and the shell portion is a soft (magnetically soft) layer in which its magnetization direction is reversed even by application of a weak magnetic field, and the other of the core portion and the shell portion is a hard (magnetically hard) layer in which its magnetization direction is reversed only by application of a strong magnetic field. A power generation sensor is produced by winding a coil around the magnetic wire. When the hard layer and the soft layer are magnetized in the same direction axially of the wire and the strength of an external magnetic field applied in a direction opposite to that magnetization direction is increased to a certain magnetic field strength, the magnetization direction of the soft layer is reversed. The reversal of the magnetization direction starts at a certain position of the magnetic wire to propagate to the entire wire, whereby the magnetization direction of the soft layer is totally reversed. At this time, the large Barkhausen effect is exhibited to induce a pulse signal in the coil wound around the magnetic wire. When the external magnetic field strength is further increased to another certain magnetic field strength, the magnetization direction of the hard layer is reversed. The magnetic field strength at which the magnetization direction of the soft layer is reversed is herein referred to as “operational magnetic field” and the magnetic field strength at which the magnetization direction of the hard layer is reversed is herein referred to as “stabilization magnetic field.” A voltage outputted from the coil is characteristically constant irrespective of the change rate of an input magnetic field (external magnetic field), and is free from chattering because of its hysteresis with respect to the input magnetic field. For this reason, the pulse signal outputted from the coil is used in a position detection device and the like. Where an alternating magnetic field is applied to the power generation sensor, two pulse signals including one positive pulse signal and one negative pulse signal are generated per each cycle. Magnets are used as a magnetic field generation source, and the alternating magnetic field is applied to the power generation sensor by relative movement of the magnets and the power generation sensor. Thus, a position can be detected by counting generated pulse signals. Since the output from the coil has electric power, a sensor of power generation type (power generation sensor) requiring no external electric power supply can be provided. That is, a peripheral circuit can also be operated by an energy outputted from the coil without the external electric power supply. An angle sensor such as an absolute encoder is intrinsically incapable of detecting an angle over a single turn. As long as the electric power is supplied, an angle of one or more turns can be detected by summing up movement amounts. If the power supply is cut however, information about the one or more turns is lost. On the other hand, a segment counter employing the power generation sensor can utilize the energy outputted from the coil even if the external electric power supply is cut off. Therefore, the segment counter can continue the counting to detect one or more turns or multiple turns. In general, however, the segment counter employing the power generation sensor can only roughly detect the angle. Where the segment counter is used for motor control requiring precise angle detection, therefore, a precise multiturn angle detection value (multiturn absolute angle detection value) is utilized, which is determined by combining the count value of the segment counter with the angle detection value of a separate precision absolute angle detector. PTL 1 and PTL 2 disclose methods and devices each adapted to combine the count value of the segment counter with the angle detection value of the precision absolute angle detector. PTL 1 utilizes a segment counter including three power generation sensors disposed at positions with a phase difference of 60 degrees. When the direction