JPH0326028B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a motor used as a drive source for robots, etc., and in particular to a motor that integrates a motor body, a reducer, and a detector for detecting the rotational position of the output shaft of the reducer. This invention relates to a high-precision, large-torque motor designed for specific purposes.

2. Description of the Related Art When driving a robot, a large torque is required, and it is also necessary to accurately detect the rotation and movement amount of a shaft such as a robot arm and control the position. Conventionally, a reduction gear was inserted between the motor and the driven part to obtain a large output torque, but the interposition of the reduction gear had the disadvantage that positioning accuracy deteriorated due to backlash of the reduction gear.

Therefore, a so-called direct drive method is being used, in which the rotor shaft of the motor is directly connected to the shaft of the driven part and the driven part is directly driven, without inserting a reducer between the motor and the driven part. . However, this direct drive method requires the motor used to have a very large torque value, and also requires a position detector for position control. If a speed reducer is used, the speed is reduced at a fixed ratio by the speed reducer, so the resolution of the detector that detects the rotational position of the motor shaft is sufficient at tens of thousands of pulses/rotation. The drive method requires a resolution of tens to millions of pulses/rotation. Therefore, it is necessary to develop a new highly accurate position detector.

Problems to be Solved by the Invention Therefore, the present invention solves the problems of the prior art described above, and provides a high-precision, large-torque motor that can detect position with high precision and outputs large torque. The purpose is to

Means for Solving the Problems In the present invention, the rotor shaft of the motor is supported in a housing at one location by a cross roller bearing, and the rotor shaft is used as a sun roller of a planetary roller speed reducer. or,
A magnetic code board of a magnetic position detector is provided on the circumference of the large diameter part of the carrier that pivotally supports the planetary roller of the planetary roller reducer, and bearings are arranged in parallel with the code board in close proximity to the large diameter part of the carrier. By allowing the carrier to be pivotally supported by the housing on the circumferential surface thereof, the motor, the reducer, and a detector for detecting the rotational position of the carrier, which is the output of the reducer, are integrated into one housing. Configure in a specific manner.

Operation When the motor is driven, the rotation of the rotor shaft of the motor is decelerated by the planetary roller reducer, and the decelerated output is output from the carrier, which is the output shaft of the reducer.
It can output large torque. Further, the rotational position of the carrier of the output shaft is read by a reading head from a magnetic code disk of a magnetic position detector provided in the large diameter portion of the carrier, and detected with high resolution.

Embodiment FIG. 1 is a partial sectional view of an embodiment of the present invention. The present invention includes a motor section 1 that converts electrical energy into mechanical rotational energy, and a motor section 1 that decelerates the rotation output from the motor section 1. It is composed of a deceleration section 2 that outputs an output. In this embodiment, the motor section 1 is composed of a permanent magnet type synchronous motor having a disk-shaped stator and a rotor, and 3 is a rotor shaft and 4 is a stator. The above rotor shaft has
A disk-shaped rotor 5 is fixed to which a plurality of permanent magnets are fixed so that their polarities alternate. The stator 4 has a winding portion (not shown) at a position facing the rotor 5 with a constant air gap. The rotor shaft 3 is rotatably supported by the stator 4 by one cross roller bearing 6 capable of supporting both axial and thrust directions.

The speed reduction section 2 utilizes a known planetary roller speed reducer, and the principle diagram of the planetary roller speed reducer is shown in FIG. Three planetary rollers 7 are pressed around the sun roller 3', and an elastic ring 8 is pressed around the three planetary rollers 7. The elastic ring 8 is formed to have a U-shaped cross section (see FIG. 1), and by applying preload to the entire circumference of both side surfaces of the elastic ring 8, the inner diameter of the elastic ring 8 is uniformly reduced. 8 and the planetary roller 7, and the contacting portion between the planetary roller 7 and the sun roller 3'. The planetary roller 7 revolves around the planetary roller 7 at a constant ratio to the rotation of the sun roller 3', and the revolution of the planetary roller 7 is taken out as an output.

In the present invention, as shown in the embodiment of FIG. 1, the rotor shaft 3 of the motor section constitutes the sun roller of the planetary roller reducer of the reduction section, and the planetary roller 7 has an inner ring 7a and an outer ring 7b. However, a rolling element 7c is interposed between the inner ring 7a and the outer ring 7b, and the inner ring 7a and the outer ring 7b are slidable relative to each other. The inner ring 7a of each planetary roller 7 is fixed to a carrier pin 10 fixed to a carrier 9, so that the carrier 9 also rotates as the three planetary rollers 7 revolve. A carrier 9 is provided on the outer peripheral surface of the carrier 9.
An absolute type magnetic code board 11 of a magnetic position detector for detecting the rotational position of the magnetic code board 11 is fixed to the housing 14.
A read head 12 of a magnetoresistive element is fixed with a constant gap. Further, a bearing 13 is provided in parallel with the magnetic code board 11, and the carrier 9 is supported by the housing 14 by the bearing 13. Further, the elastic ring 8 is pressurized on both sides of the elastic ring 8 by the housing 14, and the elastic ring 8 and the planetary roller 7, and the planetary roller 7 and the rotor shaft 3 as a sun roller are mutually connected. They are in pressure contact.

Note that 9a is a carrier shaft that is integrated with the carrier 9, and is designed to be directly connected to a driven body such as a robot. Further, the other end of the rotor shaft 3 (the end opposite to the one to which the reduction unit 2 is connected, the right side in FIG. 1) is equipped with a position detector for detecting the rotor pole position for motor control. A recess is formed in the

Next, the operation of this embodiment will be explained.

Drives the synchronous motor of the motor section 1, and drives the rotor shaft 3.
When rotated, the outer ring 7b of the planetary roller 7 that is in pressure contact with the rotor shaft 3 also rotates, and since the outer ring 7b is in pressure contact with the elastic ring 8, the planetary roller 7 revolves around the axis of the rotor shaft 3. However, the carrier 9 rotates through a carrier pin 10 fixed to the inner ring 7a of the planetary roller 7 while decelerating the rotation of the rotor shaft 3 at a constant rate. The rotational position of this carrier 9 is determined by the absolute type magnetic code board 11.
The data will be read by the read head 12 from there.

In particular, in a magnetic position detector in which information magnetically recorded on the outer peripheral surface of a cylinder is read by a reading head, the gap between the magnetically recorded cylinder peripheral surface, that is, the magnetic code disk surface, and the reading head must always be kept constant. This is important for accurately detecting the position, but in the present invention, the magnetic code disk 11 provided on the outer peripheral surface of the carrier 9 is arranged adjacently and in parallel with the bearing 13 that bears the carrier 9. As a result, there is little shaft wobbling and the gap between the magnetic code board 11 and the reading head is always kept constant with high precision. Furthermore, since the magnetic code board 11 is provided at a position where the diameter of the carrier 9 is large,
It has good resolution and can accurately detect the position of the carrier shaft 9a, ie, a driven part such as a robot.
Since the speed is reduced by a planetary roller speed reducer, there is no backlash, and the rotation of the motor is accurately transmitted to the carrier 9 and the driven section.

Effects of the Invention In the present invention, the rotor shaft of the motor is used as the sun roller of the planetary roller reducer, and the carrier shaft of the planetary roller reducer is used as the output shaft to decelerate and extract the rotation of the motor, thereby obtaining a large torque. In addition, there is no backlash, etc., and the rotor shaft and the input shaft of the reducer are the same, so compared to the conventional case where the rotor shaft and the input shaft of the reducer are axially coupled, it is easier to axially connect. There is no eccentricity between the centers of rotation of the rotor shaft and the input shaft of the reducer, which occurs along with this, and uneven rotation due to eccentricity does not occur, making it possible to accurately position driven objects such as robots driven by the output shaft of the reducer. can do.

In addition, the large-diameter portion of the carrier of the planetary roller reducer, which is the output shaft, is used as a bearing, and a magnetic code board as a position detector is provided on the circumferential surface of the carrier in parallel with the bearing. The large-diameter portion itself plays three roles: a shaft support for the planetary roller of the planetary roller speed reducer, a bearing portion for the carrier, and a magnetic code board for the position detector, which simplifies the structure. Furthermore, since the magnetic code disk of the position detector and the carrier of the output shaft are the same, the rotation that occurs due to the shaft connection is more There is no uneven rotation due to center eccentricity, and the rotational position of the output shaft can be detected accurately.

In addition, since the magnetic code board is installed on the large diameter part of the carrier, the rotational position of the output shaft can be detected with high resolution. There is little gap variation between the magnetic code disk and the reading head that reads the code from the code disk, and the rotational position can be read accurately.

Furthermore, the motor, reducer, and position detector that detects the rotational position of the output shaft are integrated into one housing, and a cross rotor bearing that pivotally supports the rotor shaft of the motor and a bearing that pivotally supports the carrier. Since the rotor of the motor, the output shaft of the reducer, and the magnetic cord board of the position detector are supported by these two, the number of parts is reduced, the structure is simple, and costs can be reduced. .

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of one embodiment of the present invention, and FIG.
The figure shows a diagram of the principle of a planetary roller speed reducer. DESCRIPTION OF SYMBOLS 1... Motor part, 2... Reduction part, 3... Rotor shaft, 4... Stator, 5... Rotor, 6... Cross roller bearing, 7... Planetary roller, 8... Elastic ring, 9... Carrier, 10...Carrier pin,
11...magnetic code board, 12...reading head,
13...Bearing.

Claims (1)

[Claims] 1 Connect the motor rotor shaft with a cross roller bearing.
The rotor shaft is a sun roller of a planetary roller reducer, and the magnetic cord of a magnetic position detector is attached to the circumferential surface of the large diameter part of the carrier that pivotally supports the planetary roller of the planetary roller reducer. A disc is provided, a reading head facing the code disc and reading the magnetic code is fixed to the housing, and a bearing is disposed adjacently and in parallel with the magnetic code disc,
The carrier is pivotally supported by the housing on the circumferential surface of the large-diameter portion of the carrier, and one detector for detecting the rotational position of the carrier, which is the output of the motor, the reducer, and the reducer, is integrally configured in the housing. A high-precision, large-torque motor characterized by: