JP2005274191A - Harmony speed reducer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact harmony speed reducer capable of solving the problem of the large-size formation of the device and acquiring high-torque output characteristics and having few variations in a rated output level. <P>SOLUTION: The harmony speed reducer comprises a wave generator; a circular spline surrounding the wave generator inside; and a flexspline 43 surrounding the circular spline inside. The flexspline 43 is constituted of maraging steel. Slits 31 are formed in a section to be measured on which torque acts. A coil 2 is arranged with a prescribed gap from the section. The harmony speed reducer is provided with an impedance detection sensor for detecting torque acting on the flexspline 43 by a coil 23 as changes in impedance based on changes in the magnetic characteristics of the section to be measured. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a structure of a harmonic speed reducer used as a speed reducer for a motor used for a drive source such as a robot, and more particularly to a harmonic speed reducer incorporating a torque sensor.

A non-contact and small-sized torque sensor is required for control of a robot or manipulator having a rotational drive system. There are various types of such torque sensors, but there is a magnetostrictive torque sensor as a method that is non-contact and advantageous for downsizing.
4A and 4B are diagrams for explaining a conventional magnetostrictive torque sensor disclosed in Patent Document 1. FIG. 4A is a schematic principle diagram of a conventional magnetostrictive torque sensor that is non-contact and advantageous for downsizing, and FIG. It is a figure which shows the harmonic reduction gear which combined this with the motor.
The magnetostrictive torque sensor shown in FIG. 4 performs torque detection using the inverse magnetostrictive effect that the magnetic permeability of a magnetic material changes when a force is applied to the magnetic material.
In the figure, 1 is a magnetic rotating shaft, 2 is a coil, 3 is a motor, 4 is a harmonic speed reducer, 5 is a load, and 33 is a film.
A change in the magnetic permeability of the magnetic rotating shaft 1 is detected as a change in impedance of the coil 2 wound around the rotating shaft 1 with a constant gap or a magnetic head (not shown) wound with the coil. Such a torque sensor is used by being incorporated in a load side rotating shaft. For example, in the case of a harmonic reduction gear combined with a motor, the configuration is as shown in FIG.
In the figure, a load 5 and a rotary shaft 1 are coupled to a motor 3 via a harmonic speed reducer 4, and a torque sensor 6 is provided on the rotary shaft 1 on the load side. In the harmonic reduction gear 4, the torque of the motor 3 is transmitted to the load-side rotating shaft through three components: a wave generator, a circular spline, and a flex spline. Among these, since the flexspline requires deformation, it is formed into a long cylindrical shape using maraging steel having a thin plate and high strength.
However, when the torque sensor is incorporated into the output shaft as shown in FIG. 4, it is necessary to make the output shaft longer (usually 20 mm or more) as much as the torque sensor. As a result, when a robot is made with this configuration, there is a problem that the robot becomes large.
Japanese Patent No. 3440951

Therefore, as a solution to the above problem, Patent Document 1 discloses a harmonic speed reducer as shown in FIG.
In the figure, 2 is a coil, 33 is a film, and 42 is a flexspline.
This harmonic speed reducer consists of a wave generator, a circular spline, and a flex spline. The flex spline forms a film 33 on the part to be measured on which the torque acts by a vacuum technique, and a coil 2 is provided with a certain gap around the film 33. Then, the torque applied to the flex spline 42 is detected by the sensor as a change in impedance based on a change in the magnetic characteristics of the part to be measured.
As shown in the figure, when film processing was performed on the peripheral portion of the flexspline 42, the problem of upsizing of the apparatus was solved, and high torque output characteristics were obtained, but variations in the rated output level occurred. This is considered to occur because the periphery of the flexspline is deformed not only in the torque application direction but also in the radial direction during the deceleration operation.
In addition, when the excitation / detection coil was not provided with a yoke, the output characteristics of the harmonic reducer and the output shaft around the iron were changed from those before installation when incorporated in equipment. This was because a reaction force was applied to the frame and the magnetostriction was detected by the coil.

  The present invention has improved these problems, and provides a small harmonized speed reducer that eliminates the problem of upsizing of the apparatus, provides high torque output characteristics, and has no variation in rated output level. is there.

In order to solve the above-mentioned problem, the harmonic speed reducer according to claim 1 is a harmonic speed reducer comprising a wave generator, a circular spline surrounding the wave generator, and a flexspline surrounding the circular spline. The flexspline is made of maraging steel, a slit or groove is formed in a measured portion where torque acts, a coil is arranged with a certain gap from the portion, and the torque applied to the flexspline is An impedance detection sensor is provided that detects the change in impedance based on the change in magnetic characteristics of the measurement site using the coil.
The harmonic speed reducer according to claim 2 is a harmonic speed reducer comprising a wave generator, a circular spline surrounding the wave generator, and a flex spline surrounding the circular spline. It is composed of maraging steel, and a film with a film thickness of 0.1 μm to 30 μm is formed on the part to be measured where torque acts, and a coil is arranged with a certain gap from the part, and the flexspline In a harmonic speed reducer equipped with an impedance detection sensor that detects such a torque as a change in impedance based on a change in magnetic characteristics of the part to be measured using the coil, the material of the film is copper, or a copper alloy or aluminum alloy. And the thermal expansion coefficient is larger than that of the maraging steel and It is characterized in that it is formed of a material having a tensile strength of 10 kg / mm ² or more or any of nickel, nickel iron alloy, nickel cobalt alloy, iron cobalt alloy, nickel iron cobalt alloy. .

A harmonic speed reducer according to claim 3 is a harmonic speed reducer comprising a wave generator, a circular spline surrounding the wave generator, and a flex spline surrounding the circular spline. Constructed from maraging steel, slits or grooves are formed at the site to be measured where torque acts, and a film with a film thickness of 0.1 μm to 30 μm is formed by a film forming technique, and a certain gap is provided from the part to form a coil In a harmonic speed reducer equipped with an impedance detection sensor that detects the torque applied to the flexspline as an impedance change based on a change in magnetic characteristics of the measurement site by the coil, the material of the film is copper, Alternatively, it is either a copper alloy or an aluminum alloy and has a thermal expansion coefficient of Made of any material that is larger than aging steel and has a tensile strength of 10 kg / mm ² or more, or nickel, nickel iron alloy, nickel cobalt alloy, iron cobalt alloy, nickel iron cobalt alloy It is characterized by.
According to a fourth aspect of the present invention, in the harmonic speed reducer according to any one of the first to third aspects, the slit, groove, and film formed in the measurement site are in a strip shape extending obliquely in the radial direction. And a plurality of these are formed along the circumference.
According to a fifth aspect of the present invention, in the harmonic reduction gear according to any one of the first to fourth aspects, the flexspline on the output side during the torque deceleration transmission operation is in relation to the input side radial surface during the torque deceleration transmission operation. It has a substantially vertical plane, and the measurement site is provided on the substantially vertical plane.
According to a sixth aspect of the present invention, in the harmonic speed reducer according to the fifth aspect, a magnetic yoke is disposed around the impedance detection sensor of the measurement site.

According to the first aspect of the present invention, the portion for detecting the torque can be made of maraging steel having magnetostriction, and the direction of the torque can be known, and the speed reduction means and the torque detection means are made the same member. The harmonic reduction gear incorporating the torque sensor can be downsized.
According to the invention described in claim 2, the magnetostriction effect of maraging steel can be further increased, the output signal due to torque can be increased, and the sensitivity is improved.
In addition, according to the invention described in claim 3, the effects of both the invention described in claim 1 and the invention described in claim 2 can be obtained, and the direction of torque can be determined and a sensitive reduction gear with high sensitivity can be obtained. It is done.
In addition, according to the fourth aspect of the invention, it is possible to efficiently extract signals and to reduce the size of the torque sensor.
According to the fifth aspect of the present invention, since the portion where the strain other than the torque is difficult to be applied to the flexspline during the deceleration operation is used as the torque detection unit, other distortion elements are not input to the detection unit, and the accuracy is high. Torque can be detected.
Further, according to the invention described in claim 6, since it is not affected by a magnetic signal from an element other than the detection unit, for example, an iron frame, torque detection with little variation with respect to other distortion elements and temperature changes can be performed. it can.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments.

An embodiment of the present invention is shown in FIG.
FIG. 1 is a configuration diagram in which a magnetostrictive torque sensor is incorporated in a flexspline, wherein (a) is a front longitudinal sectional view of the flexspline, and (b) is a side view.
In the figure, 43 is a flexspline, and 31 is a slit 31 (or groove 32) formed on the end peripheral surface of the flexspline 43 by mechanical polishing or chemical etching. Reference numeral 2 denotes a solenoid coil, which is composed of 21 excitation coils and 22 detection coils. Reference numeral 23 denotes a yoke 23.
As shown in the drawing, a slit 31 or a groove 32 is formed on the end peripheral surface of the flexspline 43 by mechanical polishing or chemical etching, and a yoke 23 is provided in the vicinity of the end peripheral portion with a gap of 0.5 mm. The coil 2 is arranged.
Further, an exciting coil 21 and a detecting coil 22 are wound around the solenoid coil.
Using this flexspline 43, the harmonized speed reducer 4 was constructed, and the torque output characteristics were examined in combination with the motor and the load.
As a result, (1) when groove processing was performed, the torque could be detected with an accuracy of ± 5% with respect to the rated torque. In addition, (2) when slit processing was performed, torque could be detected with an accuracy of ± 10%.
In addition, when no slit and groove processing was performed, only a signal that could not be distinguished from the positive direction and the negative direction was obtained with an accuracy of 30% from the torque 0 to the rated torque.

FIG. 2 is a cross-sectional perspective view of a harmony reducer incorporating the flexspline of FIG.
In the figure, 41 is a wave generator, 42 is a circular spline, and 43 is a flexspline. Reference numeral 31 denotes a slit 31 (or groove 32) formed on the end peripheral surface of the flex spline 43. Reference numeral 2 denotes a solenoid coil, which is composed of 21 excitation coils and 22 detection coils, and 23 is a yoke 23.
As shown in FIG. 2, the torque of the motor is transmitted to the rotating shaft on the load side through three components: a wave generator 41, a circular spline 42, and a flex spline 43. Of these, the flex spline 43 needs to be deformed, so it is formed into a long cylindrical shape using maraging steel having a thin plate thickness and high strength, and slits are formed on its end peripheral surface by mechanical polishing or chemical etching. 31 is formed. Although the slit 31 is a through hole, it does not have to be penetrated. In short, it is only necessary to have a cornered portion, so that the same effect, that is, the effect that the direction of torque can be determined can be obtained even with a groove having the same shape. The reason why the direction of the torque can be determined by the formation of the slit or groove is that if the slit or groove is not formed, the magnetic anisotropy of the film is equivalent to + torque and -torque application, but the direction cannot be detected. If slits and grooves are formed, the magnetic anisotropy of the film is applied in the direction of the maximum stress when torque is applied, so that the magnetic anisotropy of the film is applied by the slits and grooves. Since the magnetism is different with respect to the application direction, the direction can be detected.

In the second embodiment, instead of the slits and grooves of the first embodiment, a film is formed at that portion. After ultrasonic cleaning of flexspline 43 in the order of trichrene, pure water and alcohol, copper, copper alloy, aluminum alloy, nickel, nickel iron alloy, nickel cobalt alloy, iron cobalt alloy, nickel iron cobalt alloy in plating bath The film 33 was formed in various thicknesses. A solenoid coil 2 having a yoke 23 is disposed in the vicinity of the end of the flexspline end with a gap of 0.5 mm.
In addition, the exciting coil 21 and the detecting coil 22 are wound around the solenoid coil. Using this flex spline 43, the harmonized speed reducer 4 was constructed, and the torque output and characteristics were examined in combination with the motor and the load.

I) When plated film 33 of copper, copper alloy, or aluminum alloy is applied:
(1) When the plated film 33 of copper, copper alloy, or aluminum alloy was applied, the output level was the same as that when the film 33 was not applied at a thickness of 0.05 μm.
(2) When the film thickness was 0.1 μm, the heat treatment was performed at 400 ° C. after film deposition, and the accuracy was further improved by about 50% compared to the case of Example 1.
(3) When the film thickness was 1 μm, 5 μm, and 10 μm, the accuracy was improved by 60 to 80% compared to the case of Example 1, and the accuracy was further improved by about 50% compared to the case of Example 1 at 30 μm.
However, these cases were also equivalent if no heat treatment was performed.
(4) When the film thickness was 50 μm, no effect of film formation was observed.

II) When nickel, nickel iron alloy, nickel cobalt alloy, iron cobalt alloy, nickel iron cobalt alloy plating film is applied:
(1) When this plating film was applied, a heat treatment at 400 ° C. was performed after the film formation, and an effect of improving accuracy by 10% was seen compared to the case where the heat treatment was not performed.
(2) At 0.05 μm thickness, the output level was the same as when no film was applied.
(3) When the film thickness was 0.1 μm, the accuracy was further improved by about 40% compared to the case of Example 1.
(4) When the film thickness was 1 μm, 5 μm, and 10 μm, the accuracy was improved by 50 to 70% compared to the case of Example 1, and the accuracy was further improved by about 40% compared to the case of Example 1 at 30 μm.
(5) It was difficult to make the film thickness 50 μm in this experiment.
As described above, according to Example 2, the accuracy was further improved compared to Example 1 by forming the film.

In the third embodiment, after the slits and grooves in the first embodiment are formed, a film is further formed on the portion.
A slit or a groove was formed on the surface of the end peripheral portion of the flexspline 43 by mechanical polishing or chemical etching. Thereafter, the flexspline 43 is subjected to ultrasonic cleaning in the order of trichrene, pure water, and alcohol, and then copper, copper alloy, aluminum alloy, nickel, nickel iron alloy, nickel cobalt alloy, iron cobalt alloy, nickel in a plating bath. The iron-cobalt alloy film 33 was formed in various thicknesses. A solenoid coil 2 having a yoke 23 is disposed in the vicinity of the end of the flexspline end with a gap of 0.5 mm.
As described above, according to the third embodiment, the effects of both the first and second embodiments are achieved, the problem of the upsizing of the apparatus is solved, and the direction of torque without variation in the rated output level is eliminated. And high torque output characteristics were obtained.

  In this way, a slit or groove is formed on the end surface of the flexspline that constitutes the harmonic reduction gear, and a film is provided to detect the inverse magnetostriction effect of this end surface portion with a coil with a yoke. The torque can be detected by the harmonized speed reducer.

  Since the harmonic reduction gear can increase the output of the prime mover, it can be applied not only to the electric motor but also to applications such as hydraulics and engines.

BRIEF DESCRIPTION OF THE DRAWINGS It is the block diagram which incorporated the magnetostriction type torque sensor in the flexspline which concerns on 1st Example of this invention, (a) is a front longitudinal cross-sectional view of a flexspline, (b) is a side view. It is a cross-sectional perspective view of the harmonic reduction gear incorporating the flexspline of FIG. It is the block diagram which incorporated the magnetostriction type torque sensor in the flexspline which concerns on 2nd Example of this invention, (a) is a front longitudinal cross-sectional view of a flexspline, (b) is a side view. It is a figure explaining the conventional magnetostrictive torque sensor, (a) is a schematic principle figure of the conventional magnetostrictive torque sensor, (b) is a figure which shows the harmonic reduction gear which combined this with the motor. It is a block diagram which concerns on the prior art 2 which incorporated the magnetostrictive type torque sensor in the flexspline.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotating shaft 2 Solenoid coil 21 Excitation coil 22 Detection coil 23 Yoke 31 Slit 32 Groove 33 Film 4 Harmonic reducer 41 Wave generator 42 Circular spline 43 Flexspline

Claims (6)

A harmonic speed reducer comprising a wave generator, a circular spline surrounding the wave generator, and a flexspline surrounding the circular spline, the flexspline being made of maraging steel,
A slit or groove is formed in the measurement site where torque acts, a coil is arranged with a certain gap from the site, and the torque applied to the flexspline is changed based on the change in the magnetic characteristics of the measurement site. A harmonic speed reducer characterized by comprising an impedance detection sensor for detecting by the coil. A harmonic speed reducer comprising a wave generator, a circular spline surrounding the wave generator, and a flexspline surrounding the circular spline, the flexspline being made of maraging steel,
A film having a film thickness of 0.1 μm to 30 μm is formed by a film forming technique on a measurement site where torque acts, a coil is arranged with a certain gap from the site, and the torque applied to the flexspline is measured on the measurement site In a harmonic speed reducer equipped with an impedance detection sensor that detects an impedance change based on a change in magnetic characteristics of the coil,
The material of the film is copper, or a material having a characteristic that the thermal expansion coefficient is larger than that of the maraging steel and the tensile strength is 10 kg / mm ² or more, either copper alloy or aluminum alloy, Alternatively, a harmonized speed reducer formed of any one of nickel, nickel iron alloy, nickel cobalt alloy, iron cobalt alloy, and nickel iron cobalt alloy. A harmonic speed reducer comprising a wave generator, a circular spline surrounding the wave generator, and a flexspline surrounding the circular spline, the flexspline being made of maraging steel,
A slit or groove is formed in a measurement target site where torque acts, and a film having a film thickness of 0.1 μm to 30 μm is formed by a film forming technique, and a coil is arranged with a certain gap from the part, and the flexspline In a harmonic speed reducer equipped with an impedance detection sensor that detects the torque applied to the coil as a change in impedance based on a change in magnetic characteristics of the measurement site,
The material of the film is copper, or a material having a characteristic that the thermal expansion coefficient is larger than that of the maraging steel and the tensile strength is 10 kg / mm ² or more, either copper alloy or aluminum alloy, Alternatively, a harmonized speed reducer formed of any one of nickel, nickel iron alloy, nickel cobalt alloy, iron cobalt alloy, and nickel iron cobalt alloy.   The slits, grooves, and films formed in the measurement site are strips extending obliquely in the radial direction, and a plurality of the slits, grooves, and films are formed along the circumference. The harmonic reduction device according to any one of 3.   The output side flex spline at the time of torque deceleration transmission operation has a substantially vertical plane with respect to the input side radial surface at the time of torque deceleration transmission operation, and has the portion to be measured on the substantially vertical plane. The harmonic reduction gear of any one of 1-4.   6. The harmonic reduction gear according to claim 5, wherein a magnetic yoke is disposed around an impedance detection sensor at the measurement site.

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