JP2002078289A - Rotary drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cut the size of a device in the axial direction. SOLUTION: This rotary drive device which makes a feed-back control of a rotational speed drive by detecting an output rotation speed has a motor 1, an epicycle reduction gear 2, a magnet ring 25 and magnet sensors 26a, 26b. The reduction gear 2 which has a sun roller 15 to which the rotation of the motor 1 is inputted, an internal ring 16, a plurality of planet rollers 17 which are disposed between the internal ring 16 and the solar roller 15, a carrier 18 which support a plurality of planet rollers 17, and a housing 20 which holds the solar roller, the internal ring, the planet rollers and the carrier, outputs the rotation of the motor 1 from the carrier reducing. The magnet ring 25 is disposed in the housing 20 to rotate making one piece with the carrier 18, and the sensors 26a, 26b detect the rotation speed of the magnet ring 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary drive device, and more particularly to a photoreceptor drum of a copying machine which is driven to rotate at a low speed and with high accuracy, and in which the output rotational speed is detected and the drive rotational speed is feedback controlled. And a rotary drive device.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a printing machine, and the like, a rotation driving device for rotating a photosensitive drum and a roller for feeding a film at low speed and with high accuracy is required. This type of conventional device includes a motor and a planetary speed reducer that reduces the rotation of the motor.
As the planetary reduction gears, there are a gear reduction gear and a traction, that is, a friction transmission reduction gear.

Here, for example, in a color copying machine,
A rotary driving device is used to drive the photosensitive drum for each color component. In this case, it is necessary to control the rotation speed of each rotation drive device with high accuracy in order to prevent color shift and color unevenness. In a printing press, this type of rotation drive device is used to feed a film. In order to avoid printing unevenness, it is necessary to control the rotation speed with high precision as described above to minimize speed fluctuations. is there.

However, in a gear type reduction gear, rotation unevenness occurs due to lost motion such as a shift in meshing due to gear precision and deformation inside the reduction gear generated when torque is transmitted. In a traction type reduction gear, As a result, slippage occurs, and the output rotational speed cannot be maintained with high accuracy.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 10-161752, the output rotation speed of the speed reducer is detected by a sensor, and based on the detection result, the motor is controlled so that the output rotation speed always becomes a desired rotation speed. There is provided an apparatus for feedback-controlling the rotational speed of the motor.

In this device, a rotary encoder is provided on the output shaft of the traction reduction gear, and a detection output of the rotary encoder is input to a control unit. The control unit compares the detected value of the rotary encoder with the set value, and controls the driving of the motor so that the deviation is eliminated.

[0007]

A rotary drive of this type has a direct and high rigidity with respect to a driven device in order to avoid an assembly error of the device and resonance caused by components of a transmission system. Need to be mounted. Therefore, the motor and the reduction gear are arranged in series in the axial direction.

In such an apparatus, in order to perform the above-described feedback control, a space for installing a rotary encoder is required on the output side of the traction reduction gear. For this reason, the dimension in the axial direction becomes longer, which hinders miniaturization of the entire device on which the rotary drive device is mounted.

An object of the present invention is to reduce the axial dimension. Another object of the present invention is to realize a reduction in cost and a reduction in the number of manufacturing steps by simplifying the structure.

[0010]

According to a first aspect of the present invention, there is provided a rotary driving device for driving a driven device to rotate, detecting an output rotation speed, and performing feedback control of the driving rotation speed. , A planetary reduction gear, a magnet ring, and a magnetic sensor. The planetary speed reducer includes a sun wheel to which the rotation of the motor is input, an internal ring arranged concentrically with the sun wheel, a plurality of planet wheels arranged between the sun wheel and the internal ring, and a plurality of planetary wheels. It has a carrier for supporting the planetary car, and a housing for accommodating the sun wheel, the internal ring, the planetary car and the carrier, and reduces the rotation of the motor to output from the carrier. The magnet ring is provided so as to rotate integrally with the carrier in the housing of the reduction gear transmission, and is magnetized in a fixed pattern in the rotation direction. The magnetic sensor detects the rotation speed of the magnet ring.

In this rotary drive device, the rotation of the motor is reduced by the planetary speed reducer, and is output from the carrier to drive the driven device. At this time, the output rotation speed of the reduction gear is detected by the magnet ring and the magnetic sensor, and based on the detection result, the rotation speed of the motor is feedback-controlled so that the output rotation speed becomes a desired set speed.

Here, a magnet ring for detecting the output rotation speed is provided in the housing of the reduction gear transmission. Therefore, no space is required on the output side of the reduction gear for detecting the rotational speed, and the axial dimension can be reduced as compared with the conventional device. In particular, in the conventional apparatus, a dedicated housing for the rotary encoder for detecting the rotational speed is required. However, in the present invention, such a dedicated housing is not required, so that not only the axial dimension is shortened, but also the structure is simplified. Thus, the cost can be reduced and the number of manufacturing steps can be reduced.

Further, the presence of a lubricant such as grease in the housing of the magnet ring and the magnetic sensor does not directly affect the detection accuracy. Therefore, speed detection can be performed accurately.

According to a second aspect of the present invention, there is provided a rotary driving device.
In the above device, at least one of a torque transmitting unit between the sun wheel and the planetary vehicle and a torque transmitting unit between the planetary wheel and the internal ring transmit torque by a traction method.

Here, in the planetary speed reducer of the present invention, each of the sun wheel, the planet wheel, and the internal ring is a concept including both a gear wheel and a friction wheel having no teeth. Therefore, between the sun and planetary cars,
Each torque transmission between the planetary vehicle and the internal ring includes torque transmission by gear engagement and torque transmission by friction (traction).

Therefore, in the device according to the second aspect, it is limited that the speed reducer includes a traction type torque transmission. When torque is transmitted by the traction method, slippage occurs. Here, the slip, that is, the deviation between the output rotation speed detected by the rotation speed sensor and the set value is obtained, and control is performed to eliminate the deviation so that the output rotation speed is maintained at the desired set value. I have.

According to a third aspect of the present invention, there is provided a rotary drive device.
Alternatively, in the device of the second aspect, the magnet ring is fitted to the outer peripheral portion of the carrier so as not to rotate relatively. Here, the magnet ring and the carrier are provided so as to overlap in the axial direction, so that the space in the axial direction can be further reduced. Further, since the carrier also serves as the support member for the magnet ring, the configuration is simplified.

According to a fourth aspect of the present invention, there is provided a rotary driving device.
In the apparatus according to the second aspect, the speed reducer has an output shaft that rotates integrally with the carrier, and further includes a disc that has a hole in which the output shaft fits at a center portion and that rotates integrally with the output shaft, The ring is mounted on the outer periphery of the disk.

Here, a disk is fitted to the output shaft in the reduction gear transmission, and a magnet ring is mounted on the outer periphery of the disk. As described above, when the magnet ring is fitted to the outer circumference of the carrier, the outer circumference of the carrier is cut with high precision to avoid the interference between the magnet ring and the magnetic sensor so that the radial position of the magnet ring can be accurately determined. Need to position. For this reason, the number of steps may increase.

Therefore, in the apparatus according to the fourth aspect, a disk is fitted to the output shaft, and a magnet ring is mounted on the outer periphery of the disk. That is, the magnet ring is installed with reference to the outer circumference of the output shaft. Since the outer periphery of the output shaft is generally cut with high precision, there is no need to add a special process for attaching the magnet ring.

According to a fifth aspect of the present invention, there is provided a rotary driving device.
In the above device, the disk is provided in contact with the side surface of the carrier, and the magnet ring is disposed so as to overlap the carrier in the axial direction of the reduction gear transmission.

Here, as described above, since the magnet ring and the carrier are arranged so as to overlap in the axial direction, the axial length can be reduced. According to a sixth aspect of the present invention, there is provided a rotary drive device according to any one of the first to fifth aspects, wherein a pair of magnetic sensors are provided outside the magnet ring at 180 ° intervals in the circumferential direction.

Here, by detecting the rotational speed based on the outputs from the plurality of sensors, it is possible to accurately detect the rotational speed even when the magnet ring is eccentrically provided.

[0024]

[First Embodiment] FIG. 1 shows a rotary drive device according to a first embodiment of the present invention.

The rotary driving device shown in FIG.
A speed reducer 2 of a planetary system for decelerating and outputting the rotation from the motor 1 and a speed detecting mechanism 3 for detecting an output rotational speed of the speed reducer 2. Further, the rotation drive device further includes a controller 4 to which an output from the speed detection mechanism 3 is input, and a drive device 5 for controlling the rotation speed of the motor 1 according to a control signal from the controller 4.

The motor 1 is fixed to the side surface of the reduction gear 2, and the motor flange and the side wall of the reduction gear 2 are shared. The rotary drive shaft 10 is provided at the center of the motor 1. The rotary drive shaft 10 is rotatably supported by a pair of bearings 11 and 12, and the distal end thereof is
Roller 15 which enters the inside and is an input portion of the reduction gear 2
Is composed.

The speed reducer 2 controls the rotation of the motor 1 by, for example, 1
The rotation speed is reduced to about rotation / sec.
, The internal ring 16 and a plurality (3 in this embodiment)
(Only two are shown in the figure) and the carrier 1 that supports the plurality of planetary rollers 17.
8 and an output shaft 19. The sun roller 15, the internal ring 16, the plurality of planetary rollers 17 and the carrier 18 are housed in a housing 20, and the housing 20 is filled with grease as a lubricant.

The internal ring 16 is an annular member, and is fixed to the inner wall of the housing 20 concentrically with the sun roller 15. Each of the plurality of planetary rollers 17 cantileverly supports a rod 21, and each rod 21 is rotatable with respect to the carrier 18. In addition, each planet roller 17
Is in contact with the outer peripheral surface of the sun roller 15 and also on the inner peripheral surface of the internal ring 16, and each abutting portion is adapted to transmit torque by a traction method. With such a configuration, each planetary roller 17 can rotate while revolving around the sun roller 15. The carrier 18 is a ring-shaped member, and an output shaft 19 is inserted into a hole at the center and fixed to each other so as not to rotate relative to each other. The output shaft 19 is rotatably supported by a housing 20 by a bearing 22. Note that the carrier 18 and the output shaft 19 can be formed integrally.

The speed detecting mechanism 3 includes a magnet ring 25 fitted and fixed to the outer peripheral surface of the carrier 18, and a magnet ring 25 disposed at a predetermined gap from the outer peripheral surface of the magnet ring 25.
It has a pair of magnetic sensors 26a and 26b. As shown in FIG. 2, the magnet ring 25 is an annular member, and is formed by, for example, magnetizing about 650 N poles and S poles alternately and at equal intervals in the circumferential direction. The magnetic sensors 26a and 26b are each composed of a magnetoresistive element (MR element), and are arranged at positions facing each other (at 180 ° intervals).

The controller 4 includes a crystal oscillator, a frequency divider,
A control circuit including a phase difference detecting unit, a driving pulse output unit, and the like, and outputs a motor driving pulse based on detection outputs from the two magnetic sensors 26a and 26b so that the output rotation speed becomes a desired set value. Circuit. The driver device 5 is a device for driving the motor 1 based on a drive pulse from the controller 4.

Next, the operation will be described. Motor 1
When the rotary drive shaft 10 rotates by driving
This rotation is input to the speed reducer 2. This rotation is performed by the sun roller 15, the planetary roller 17 and the internal ring 16.
Are decelerated by a reduction ratio determined by the outer diameter and the inner diameter of the motor, and are output via the carrier 18 and the output shaft 19.

At this time, since the output shaft 19 and the carrier 18 rotate at the same rotational speed, the output rotational speed can be detected by detecting the rotational speed of the carrier 18.

Therefore, in this embodiment, the carrier 18
The rotational speed of the carrier 18 is detected as a pulse signal by the magnet ring 25 fixed to the outer periphery of the sensor and the magnetic sensors 26a and 26b, and the pulse signal is input to the controller 4. The controller 4 compares the detection signals of the two magnetic sensors 26a and 26b and synthesizes the rotation signal of the carrier 18 in a state where the magnet ring 25 is correctly attached. Then, a phase difference between the synthesized signal and a rotation reference pulse (a pulse corresponding to the uniform rotation of the carrier 18) is detected, and a control signal for eliminating the phase difference is input to the drive device 5. This control is described in JP-A-11-3418.
No. 54 discloses this in detail. Then, the rotation speed of the motor 1 is increased or decreased by a drive signal from the drive device 5.

With such feedback control,
The rotation speed of the motor 1 is controlled so that the output rotation speed of the reduction gear 2 becomes a desired set speed. In this device, a magnet ring 25 and magnetic sensors 26a and 26b constituting the speed detecting mechanism 3 are arranged in a housing 20 of the speed reducer 2. Therefore, the axial dimension of the entire apparatus can be reduced as compared with the case where a mechanism for detecting the speed is further disposed on the output side of the housing 20 as in the conventional apparatus. Further, the magnet ring 25 is attached to the carrier 18.
, And both members overlap in the axial direction. For this reason, the axial dimension can be reduced, for example, as in the case where the magnet ring is arranged on the side of the carrier 18.

Although the housing 20 of the reduction gear 2 is filled with grease as a lubricant, the accuracy of the rotation speed detection by the magnet ring 25 and the magnetic sensors 26a and 26b is not reduced by the grease. Absent.

[Second Embodiment] FIG. 3 shows a second embodiment of the present invention. In this embodiment, only the speed detection mechanism is the first
Unlike the embodiment, other configurations are the same.

The speed detecting mechanism 30 according to the second embodiment includes:
It has a disk 31 and a magnet ring 32 fixed to the outer periphery of the disk 31. The disc 31 has a hole 31 in the center
The outer peripheral surface of the output shaft 19 is fitted into the hole 31a such that it cannot rotate relative to the disk 31. In addition, disk 3
Numeral 1 is disposed in contact with the output side surface of the carrier 18. The magnet ring 32 has the same configuration as in the first embodiment. The magnet ring 32 extends radially outward of the carrier 18 in the axial direction.
And are arranged to overlap.

Here, in the first embodiment, the outer peripheral surface of the carrier 18, which normally does not need to be processed, is specially processed, a magnet ring is fitted, and radial positioning (centering) of the magnet ring is performed. ing. However, in the second embodiment, the centering of the magnet ring 32 is performed on the output shaft 1.
9 with reference to the outer peripheral surface. Since the outer peripheral surface of the output shaft 19 is usually cut with high precision, a special cutting process for centering the magnet ring 32 is not required, and an increase in the number of processing steps can be prevented.

Further, similarly to the first embodiment, since the magnet ring 32 is disposed so as to overlap the carrier 18 in the axial direction, the axial dimension can be further reduced.

[Third Embodiment] FIG. 4 shows a third embodiment of the present invention. This embodiment differs from the first embodiment only in the speed reducer portion, and other configurations are the same as those in the first embodiment.

The speed reducer 40 in the third embodiment
Is a planetary system similar to the above-described embodiment, and includes a sun roller 15, an internal ring 41, and a plurality of planetary rollers 4.
2, a carrier 18 that rotatably supports each planetary roller 42, and an output shaft 19.

The internal ring 41 has an annular fixed ring 41a and a movable ring 41b, respectively.
The two rings 41 a and 41 b are provided to face each other with the planetary roller 42 interposed therebetween. The fixing ring 41 a is fixed to the housing 43 so as not to move in the axial direction and the rotation direction. The movable ring 41b is
3 is mounted so as to be movable in the axial direction and to be relatively non-rotatable. The opposed surfaces of the inner peripheral portions of both rings 41a and 41b are each formed in a tapered shape.

The planetary roller 42 is rotatably supported by the rod 18 in a cantilever manner with respect to the carrier 18, and includes a large-diameter roller portion 42a and a small-diameter roller portion 42b. The outer peripheral surface of the large-diameter roller portion 42a is the sun roller 15
Is in contact with the outer peripheral surface of. The small-diameter roller 42b is connected to the large-diameter roller 42a from the center of both sides of the large-diameter roller 42a.
It is formed concentrically with and protruding in a truncated cone shape. The fixing ring 4 is attached to the tapered surface of the small-diameter roller portion 42b.
Tapered surfaces formed on the inner peripheral surfaces of the movable ring 1a and the movable ring 41b are in contact with each other.

A compression coil spring 44 is disposed on the output side of the movable ring 41b, and the movable ring 41b is constantly biased toward the fixed ring 41a by the compression coil spring 44. Thereby, each contact surface between the large-diameter roller portion 42a of each planetary roller 42 and the sun roller 15, the small-diameter roller portion 42b, the fixed ring 41a and the movable ring 41b
A predetermined pressure contact force can be applied to the respective contact surfaces with the contact.

The speed detecting mechanism is the same as that of the first embodiment. A magnet ring 25 fitted and fixed to the outer peripheral surface of the carrier 18 is disposed at a predetermined gap from the outer peripheral surface of the magnet ring 25. And a pair of magnetic sensors 26a and 26b.

In the planetary speed reducer having such a structure, the same operation and effect as described above can be obtained, and the entire device can be shortened in the axial direction. [Other Embodiments] (a) In the above-described embodiment, a member constituting the reduction gear is a friction wheel such as a roller, and traction is provided between the sun roller and each planetary roller and between each planetary roller and the internal ring. Although the traction method is used, a part of the traction method may be used. Further, the sun wheel, the planet wheel, and the internal ring may be a sun gear, a planetary gear, and a ring gear, respectively, and each torque transmission unit may be a meshing system using gears.

(B) Although a pair of magnetic sensors is provided in the speed detection mechanism, the rotation speed may be detected by one magnetic sensor.

[0048]

As described above, according to the present invention, since the object to be detected for detecting the rotational speed is arranged inside the reduction gear, the axial dimension of the entire apparatus can be reduced. Further, simplification of the structure can reduce the cost and reduce the number of manufacturing steps.

[Brief description of the drawings]

FIG. 1 is a sectional configuration diagram of a rotary drive device according to a first embodiment of the present invention.

FIG. 2 is a partial front view of the magnet ring.

FIG. 3 is a sectional configuration diagram of a rotary drive device according to a second embodiment of the present invention.

FIG. 4 is a sectional configuration diagram of a rotary drive device according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Motor 2,40 Reduction gear 4 Controller 5 Drive device 15 Sun roller 16,41 Internal ring 17,42 Planetary roller 18 Carrier 20 Housing 25,32 Magnet ring 26a, 26b Magnetic sensor 31 Disk

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G01P 3/487 G01P 3/487 G H02K 11/00 H02K 11/00 B (72) Inventor Keisuke Yamada Kyoto Prefecture No. 1 Kamashiterada, Nagaokakyo-shi Nidec-Shimpo Corporation F-term (reference) 2F077 AA43 CC02 NN04 NN24 PP05 VV02 3J051 AA01 BA03 BB06 BC02 BD02 BE03 BE04 EA02 EB04 EC01 EC10 ED11 FA08 5H607 AA00 BB01 BB17 CB17 CC03 CC07 DD07 AA01 BB01 BB08 PP05 QQ01 RR02 UA01 UA07

Claims (6)

[Claims] 1. A rotary drive device that drives a driven device to rotate and detects an output rotation speed to feedback-control a drive rotation speed, wherein a motor as a rotation drive source and a rotation of the motor are input. A solar car, an internal ring arranged concentrically with the solar car, a plurality of planetary cars arranged between the sun car and the internal ring, a carrier supporting the plurality of planetary cars, A planetary speed reducer for reducing the rotation of the motor and outputting from the carrier; and a planetary speed reducer having a housing for housing the sun wheel, the internal ring, the planetary wheel, and the carrier; A magnet ring provided so as to rotate in a fixed manner and magnetized in a constant pattern in the rotation direction; and for detecting a rotation speed of the magnet ring. And a magnetic sensor. 2. A torque transmission unit between the solar vehicle and the planetary vehicle and / or a torque transmission unit between the planetary vehicle and the internal ring perform torque transmission by a traction method. 2. The rotation drive device according to 1. 3. The carrier according to claim 1, wherein the magnet ring is fitted to an outer peripheral portion of the carrier so as to be relatively non-rotatable.
3. The rotary drive device according to claim 1. 4. The speed reducer has an output shaft that rotates integrally with the carrier, and further includes a disc that has a hole at the center where the output shaft fits and that rotates integrally with the output shaft. The rotation drive device according to claim 1, wherein the magnet ring is attached to an outer peripheral portion of the disk. 5. The apparatus according to claim 4, wherein said disk is provided in contact with a side surface of said carrier, and said magnet ring is arranged so as to overlap with said carrier in an axial direction of said reduction gear. A rotary drive as described. 6. The rotary drive device according to claim 1, wherein a pair of said magnetic sensors is provided at an interval of 180 degrees in a circumferential direction outside said magnet ring.