JP3440951B2 - Harmonic reducer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a harmonic reduction gear used as a reduction gear of a motor used for a driving source of a robot or the like, and more particularly, to a motor incorporating a torque sensor. It relates to a harmonic reducer. 2. Description of the Related Art A non-contact and small torque sensor is required for controlling a robot or a manipulator having a rotary drive system. There are various types of such torque sensors, and a magnetostrictive torque sensor is a non-contact and advantageous type for downsizing. As shown in the schematic structure in FIG. 2, torque detection is performed by utilizing the inverse magnetostrictive effect that the magnetic permeability of the magnetic material changes when a force is applied to the magnetic material. A change in the magnetic permeability of the magnetic rotating shaft 1 is detected as an impedance change 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 into a load-side rotating shaft. For example, in the case of a harmonic reducer combined with a motor, the configuration is as shown in FIG.
A load 5 through the motor 3 two harmonized reduction gear 4 are the rotary shaft 1 is a bond, the torque sensor 6 to the rotation axis of the load-side
Is provided. The harmonic reducer has the structure shown in FIG.
1. Circular spline 42, flex spline 4
And transmitted to the rotating shaft on the load side via the three components.
Of these, the flexspline requires deformation,
Using a maraging steel with a thin plate and high strength,
It is formed in a long cylindrical shape. However, when a torque sensor is incorporated in an output shaft as shown in FIG. 3, the output shaft needs to be longer (usually 30 mm or more) by the amount of the torque sensor. As a result, there is a problem that the size of the robot is increased when the robot is manufactured with this configuration. The present invention has been made to solve these problems, and provides a small-sized harmonic reduction gear incorporating a torque sensor. [0004] A harmonic reduction gear according to the present invention comprises:
Wave generators, circular splines and filters
Lex spline, and the flex spline is
A film is formed on the part to be measured where the
The coil is arranged with a certain gap around the
The torque applied to the spline is determined by the magnetic characteristics of the measured part.
Detected as a change in impedance based on the change in
The flex spline is
Zing steel, the material of the film is copper, copper alloy, aluminum
Aluminum alloy and the coefficient of thermal expansion is
Larger than ruaging steel, with a tensile strength of 20kg /
0.1 to 30 mm ²
It was formed to a thickness of μm. The means for providing this film is described in Japanese Patent Application No.
-70328 (JP-A-5-231967). [0005] Since the torque sensor is incorporated in a part of the flex spline connected to the output shaft of the harmonic reducer, it is not necessary to increase the length of the output shaft, and the output shaft can be made compact. In addition, by coating the film on a part of the outer circumference of the flexspline,
The torque output characteristics of the rotating shaft made of maraging steel can be greatly improved. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing an embodiment. FIG. 1 shows an embodiment of the present invention. FIG. 1 is a configuration diagram in which a magnetostrictive torque sensor is incorporated in a flexspline. The film 3 is formed on the outer peripheral surface of the flexspline 43.
Are formed, and the coil 2 for torque detection is arranged via a gap. The flexspline 43 made of maraging steel was subjected to ultrasonic cleaning in the order of trichlene, pure water, and alcohol, and then set in various vacuum chambers (sputtering, ion plating, laser).
After evacuating to 5 × 10 ⁻² Torr or less, the flexspline 43 was heated to 300 to 600 ° C. to form copper, copper alloy, and aluminum alloy films of various thicknesses. Using this flexspline 43, a harmonic reduction gear 4 was constructed, and the torque output and characteristics were examined in combination with a motor and a load.
The results are shown in Tables 1 to 3. Table 1 shows copper as the film material
Table 2 shows aluminum alloy, Table 3 shows chromium
And sensors using aluminum respectively
This is the output voltage obtained . The output when no film is formed is 0.1V. [Table 1] [Table 2] [Table 3] As can be seen from Tables 1 to 3, it has a value larger than the thermal expansion coefficient of the rotating shaft 1 and has a tensile strength of 20 kg.
/ Mm ² or more of copper, copper alloy and aluminum alloy films have a thickness of 0.1 to 30 μm and a formation temperature of 300 to 550.
It can be seen that the torque output in the range of ° C. is larger than that of the conventional method. On the other hand, films having a small coefficient of thermal expansion such as Cr and Al having a small tensile strength had a small output and had no effect (Table 3). It was confirmed that torque could be detected in the same way as when a torque sensor was incorporated in the output shaft. In the present embodiment, the structure is shown in which the motor is incorporated, but the size can be reduced similarly in combination with a hydraulic unit. As described above, according to the present invention, since the magnetostrictive torque sensor is provided on the flexspline of the harmonic reducer, there is no need to newly take up space for incorporating the torque sensor on the output shaft. This has the effect of reducing the size of the harmonic reduction gear. As a result, it can greatly contribute to downsizing of a robot or the like.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of a flexspline of the present invention in which a magnetostrictive torque sensor is incorporated. FIG. 2 is a configuration diagram of a magnetostrictive torque sensor. FIG. conditioner <br/> reducer configuration Figure 4 description of the code is a diagram showing a structure of a conditioner reducer 1 rotating shaft 2 coil 3 film 4 conditioner reducer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-187771 (JP, A) JP-A-2-262828 (JP, A) JP-A-63-252487 (JP, A) JP-A-63-252 182535 (JP, A) JP-A-59-164931 (JP, A) JP-A-63-297545 (JP, A) JP-A-1-225182 (JP, A) JP-A-3-231127 (JP, A) 61-22953 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16H 1/32

Claims (1)

(57) [Claims] [Claim 1] Wave generator, circular plug
And the flexspline
The line is filmed by vacuum technology on the part to be measured where torque acts.
Is formed, and a coil is arranged with a certain space around it
And the torque applied to the flexspline is measured
Change in impedance based on the change in magnetic properties of the part
In a harmonic reduction gear provided with a sensor for detecting the flex spline, the flex spline is made of maraging steel.
The material of the film is copper, copper alloy or aluminum alloy
And the thermal expansion coefficient is larger than that of the maraging steel.
Listen, tensile strength is have a 20kg / mm ² or more properties
And formed to a thickness of 0.1 to 30 μm.
A harmonic reduction gear characterized by the above.