JP4695287B2 - Rotation drive - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotary drive device, and more particularly to a rotary drive device that can rotationally drive a driven device and can detect an output rotational speed and feedback control the drive rotational speed.
[0002]
[Prior art]
In an image forming apparatus such as a copying machine, a printing machine, or the like, a rotation driving device for rotating a photosensitive drum or a roller for feeding a film with relatively low speed and high accuracy is required. The rotational drive device disclosed in Japanese Patent Laid-Open No. 10-161752 includes a motor, a planetary reduction device that decelerates the rotation of the motor, a transmission means, a speed detection mechanism, and a feedback control means.
[0003]
The planetary reduction device includes a gear reduction device and a traction, that is, a friction transmission reduction device. The speed reducer includes a sun roller, a planetary roller, and a carrier that are formed on the output shaft of the motor. The transmission means mainly has an output shaft extending from the reduction gear side to the driven device side. The output shaft is rotatably supported by the housing via a bearing such as a ball bearing.
[0004]
The speed detection mechanism includes, for example, a rotary encoder including a pulse plate and a photodetector that detects the pulse plate. The feedback control means controls the motor based on the rotation speed detected by the speed detection mechanism.
[0005]
Here, the speed detection mechanism is disposed on the output side of the housing of the speed reducer, and therefore, the dimension in the axial direction of the rotary drive device is long. However, for example, when a rotary drive device is used in a color copying apparatus, the demand for space saving has increased, and the demand for a rotary drive device that is short in the axial direction has increased. Therefore, the applicant of the present application arranged the speed detection mechanism in the housing of the speed reducer in Japanese Patent Application No. 2000-262539 and moved the urging member of the speed reducer to the wall surface on the motor side. As a result, an unprecedented rotary drive device shortened in the axial direction was realized.
[0006]
[Problems to be solved by the invention]
The demand for the rotary drive device is not limited to shortening in the axial direction. There is also a demand for cost reduction and long-term stable operation from other applications, that is, space, and a rotary drive device that can cope with this is also required.
[0007]
Accordingly, the applicant of the present invention invented a structure in which a speed detection mechanism is arranged in a housing of a reduction gear and a seal member is provided between a carrier and a planetary roller in Japanese Patent Application No. 2000-262540. In this reduction gear, the lubricating oil, wear powder, etc. in the housing of the reduction gear are prevented from entering the speed detection mechanism and contaminating the pulse plate and the photodetector. As a result, in addition to the shortening of the rotational drive device in the axial direction, an accurate rotational speed can be detected and a stable operation over a long period of time can be realized.
[0008]
However, since the speed detection mechanism and the speed reducer are housed in the same housing, the speed detection mechanism and the seal member are arranged in a complicated manner, and the number of parts is increased.
[0009]
SUMMARY OF THE INVENTION An object of the present invention is to realize a rotary drive device that has a smaller number of parts and processing man-hours than before and can operate stably for a long time even at the expense of shortening in the axial direction.
[0010]
[Means for Solving the Problems]
Rotation driving apparatus uses the motor as a rotation drive source, thereby rotating the driven device, by detecting the output rotation speed, a rotation driving device for feedback control of the driving rotational speed of the motor, a deceleration device A transmission means, a speed detection mechanism, a housing, a first bearing, and a second bearing are provided. The reduction gear is driven by a motor. The transmission means has an output shaft extending from the reduction gear toward the driven device, and transmits the output of the reduction gear to the driven device. The speed detection mechanism is a mechanism that is disposed on the driven device side of the speed reducer and detects the rotational speed of the output shaft. The housing is formed integrally with the outer wall portion that covers the periphery of the output shaft and the speed detection mechanism, the first partition wall portion that is integrally formed on the driven device side of the outer wall portion and through which the output shaft passes, and the speed reducer side of the outer wall portion. And a second partition wall through which the output shaft passes. The first bearing is disposed between the inner peripheral surface of the first partition wall and the output shaft. The second bearing is disposed between the inner peripheral surface of the second partition wall and the output shaft. The second partition part forms an accommodation space part in which the speed detection mechanism is installed together with the first partition part and the outer wall part, and separates the speed reduction device and the speed detection mechanism in the axial direction.
[0011]
In this rotation drive device, the rotation of the motor is decelerated by the reduction device and is output from the output shaft of the transmission means to drive the driven device. At this time, the output rotation speed of the reduction gear is detected by the speed detection mechanism, and the rotation speed of the motor is feedback-controlled so that the output rotation speed becomes a desired set speed based on the detection result.
[0012]
In this rotary drive device, a housing that has conventionally been composed of a plurality of parts is formed by integral molding, and a member (seal member only for preventing impurities in the speed detection mechanism by the second partition wall portion and the second bearing) ) Is not necessary, the number of parts and the number of processing steps as a whole can be reduced, and the rigidity and assembly accuracy of the housing can be improved. Furthermore, since the second partition and the second bearing separate the speed reduction device and the speed detection mechanism in the axial direction, lubricant such as grease and wear powder generated in the speed reduction mechanism enter the speed detection mechanism. And can operate stably for a long period of time by accurate speed detection.
[0013]
For example, the housings, opening portions for installing a speed detecting mechanism housing space is formed. It is possible to perform the installation of the speed detection mechanism utilizing the window formed on the housings, the housing is easy to assemble work be integrally molded.
[0014]
For example, the window portion penetrates the outer wall portion in the radial direction of the output shaft. The central axis of the window portion extends in the penetrating direction and is orthogonal to the output shaft.
[0015]
For example, velocity detection mechanism is composed of a detection means, and the detected member to be detected by integral rotation detecting means and the output shaft. The window portion includes a first window portion for installing the member to be detected in the accommodation space portion, and a second window portion in which the detection means is disposed.
[0016]
For example, the first window portion passes through the outer wall portion in the first radial direction of the output shaft. The central axis of the first window portion extends in the first radial direction and is orthogonal to the output shaft. The second window portion passes through the outer wall portion in the second radial direction of the output shaft. The central axis of the second window portion extends in the second radial direction and is orthogonal to the output shaft.
[0017]
For example, the housings, adjustment window for adjusting the mounting position when arranging the detection means.
[0018]
In this rotary drive device, the presence of the adjustment window allows the detection means to be attached to a desired position with high accuracy even when the housing is integrally formed. Windows for adjustment penetrates in the axial direction of the output shaft of the first partition wall. The central axis of the adjustment window portion extends in the penetrating direction and is parallel to the output shaft.
[0019]
For example, velocity detection mechanism is a magnetic sensor. The detection means is at least one magnetic detection means for detecting a change in magnetic flux, and the detection member is a magnetic detection member having a magnetized portion.
[0020]
For example, velocity detection mechanism is an optical sensor. The detection means is at least one optical detection means for detecting an optical change, and the detection member is an optical detection member.
[0021]
For example, the member to be detected has a substantially disc shape having a center hole that is movably fitted in the axial direction with respect to the output shaft. The output shaft has a first engaging portion. The member to be detected has a second engagement portion that engages with the first engagement portion so as not to rotate relative to the first engagement portion and is detachable in the axial direction. The rotation drive device further includes an elastic member that urges the detected member in the axial direction so that the first engagement portion and the second engagement portion engage with each other.
[0022]
In this rotary drive device, since the first engaging portion and the second engaging portion that are detachable in the axial direction are engaged by the biasing force of the elastic member, the detection member can be easily attached. For example, the second engaging portion is formed on the surface of the detected member on the speed reduction device side, and the elastic member is disposed between the first bearing and the detected member.
[0023]
In this rotational drive layer device, since the first bearing is used as a member for supporting the elastic member, a special member is not required and the number of parts is reduced. For example, deceleration device includes a sun wheel which rotation of the motor is inputted, and the inter null ring disposed to the sun wheel and concentric contact with the sun wheel, a plurality abutting while receiving an urging force from the inter null ring A planetary vehicle and a carrier that supports the plurality of planetary vehicles and is coupled to the output shaft are included.
[0024]
In this rotary drive device, the speed reducer receives the planetary wheel from the internal ring and transmits torque by friction (traction). For example, the output shaft of the motors constitute the sun wheel of the reduction gear.
[0025]
For example, a recess for accommodating the biasing member is formed on the surface of the second partition wall on the speed reduction device side. The bottom surface of the recess is located further on the driven device side than the speed reducer side end surface of the second bearing.
[0026]
In this rotary drive device, by providing a recess in the second partition wall, the axial size of the rotary drive device can be shortened by an axial dimension in which the biasing member and the second bearing overlap in the radial direction. For example, housings further includes a second outer wall portion covering the periphery of the integrally formed speed reduction gear from the outer wall portion.
[0027]
In this rotary drive device, the housing functions as an integral member that covers both the transmission means and the speed reduction device, and thus the structure is simplified .
[0028]
For example, based on the detection of the velocity detecting mechanism further includes a feedback control means for feedback controlling the driving speed of the motor. For example, the width dimension of the first window is formed larger than the outer dimension of the member to be detected. A member to be detected is arranged in the accommodation space through the first window. By inserting the output shaft into the housing in this state, the output shaft passes through the center hole of the second partition wall, the center hole of the member to be detected, and the center hole of the first partition wall.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
1. First Embodiment (1) Configuration FIG. 1 shows a rotary drive device 1 according to an embodiment of the present invention. The rotation driving device 1 is used for an image forming apparatus, for example. The rotation drive device 1 includes a motor 2, a planetary speed reduction device 3 that decelerates and outputs rotation from the motor 2, and a transmission unit 4 that outputs the output of the speed reduction device 3 to an image forming apparatus as a driven device. It consists of and. The transmission means 4 has an output shaft 7 and a speed detection mechanism 8 for detecting the output rotation speed. The rotation drive device 1 further includes a controller 5 to which an output from the speed detection mechanism 8 is input, and a drive device 6 that controls the rotation speed of the motor 2 in accordance with a control signal from the controller 5.
[0030]
Note that OO shown in FIG. 1 is the rotation axis of the rotary drive device 1. Hereinafter, for convenience of explanation, the direction in which the rotation axis extends is the axial direction, the right side of FIG. 1 is the axial input side, and the left side of FIG. 1 is the axial output side. A direction rotating with respect to the rotation axis is defined as a rotation direction or a circumferential direction. The direction of the circle radius drawn around the rotation axis is the radial direction.
[0031]
The motor 2 is driven by a drive signal from the drive device 6 and functions as a rotational drive source of the rotational drive device 1. The motor 2 is mainly composed of a bracket 10, a stator 11, and a rotor 12.
[0032]
The bracket 10 is comprised from the cylindrical part 10a and the flange 10b extended from the one end to the outer peripheral side. Further, a base substrate 10c is attached to one side surface of the flange 10b, and a support member 10d that supports the base substrate 10c is attached to the other side surface. The motor 2 is fixed to the side surface of the reduction gear 3. Specifically, the support member 10 d is fixed to a housing 31 (described later) of the transmission means 4 by a bolt 9.
[0033]
The stator 11 has a coil wound around an iron core formed by laminating a plurality of magnetic plates, and is fixed to the outer periphery of the cylindrical portion 10 a of the bracket 10. The rotor 12 includes a rotor yoke 15 and a rotor magnet 16. The rotor yoke 15 has a thin plate shape made of a magnetic material and has a uniform thickness. Specifically, the rotor yoke 15 is composed of a disc-shaped vertical wall 15a and a cylindrical annular wall 15b extending from the outer periphery to the speed reduction device 3 side.
[0034]
The rotor magnet 16 is a cylindrical member having a plurality of poles arranged in the circumferential direction, and is fixed to the inner peripheral surface of the annular wall 15b. Thus, the rotor magnet 16 is disposed concentrically facing the stator 11 in the radial direction.
[0035]
The rotational drive shaft 14 is an output shaft of the motor 2, extends in the tubular portion 10 a of the bracket 10, and is rotatably supported by the tubular portion 10 a by a plurality of bearings 18 and 19 arranged in the axial direction. Each of the bearings 18 and 19 is a bearing having a sealing function, and prevents the lubricant from the reduction gear 3 from leaking to the motor 2 side and preventing the lubricant of the bearing from entering the reduction gear 3 side. ing. The tip of the rotational drive shaft 14 (on the side of the speed reduction device 3) enters the speed reduction device 3 and constitutes the sun roller 20 that is the input shaft of the speed reduction device 3. The end of the rotary drive shaft 14 (opposite the speed reduction device 3) is fixed to the inner peripheral portion of the vertical wall 15a of the rotor yoke 15.
[0036]
The reduction gear 3 is a one-stage system and further employs a differential planetary system. More specifically, the speed reduction device 3 is a traction type that presses and drives a metal roller, and has a smaller angular velocity variation than that of a speed reduction device that uses gears, and further has excellent low noise, low vibration, and low backlash. It has a function.
[0037]
The speed reduction device 3 reduces the rotation of the motor 2 to, for example, about 1 rotation / second, and includes the above-described sun roller 20, internal ring 21, and a plurality of (three in the present embodiment) planetary rollers 22. And a carrier 23 that supports the planetary roller 22. The sun roller 20, the internal ring 21, the plurality of planetary rollers 22, and the carrier 23 are housed in a housing (described later) filled with grease as a lubricant. In addition, depending on the material or specification of each member constituting the speed reducer 3, it may be used as a dry type without a lubricant.
[0038]
Each of the internal rings 21 has an annular fixed ring 21a and a movable ring 21b, and both the rings 21a and 21b are provided to face each other with the planetary roller 22 interposed therebetween. The fixing ring 21a is fixed to the support member 10d so as not to move in the axial direction and the rotation direction. The movable ring 21b is mounted so as to be movable in the axial direction with respect to the housing and not to be relatively rotatable. And the surface which the inner peripheral part of both the rings 21a and 21b opposes is formed in the taper shape, respectively.
[0039]
The planetary roller 22 is supported by the rod 23a so as to be cantilevered and rotatable with respect to the carrier 23. The planetary roller 22 includes a large-diameter roller portion 22a and a small-diameter roller portion 22b. The outer peripheral surface of the large-diameter roller portion 22 a is in contact with the outer peripheral surface of the sun roller 20. The small-diameter roller portion 22b is formed so as to protrude concentrically with the large-diameter roller portion 22a from a central portion on both sides of the large-diameter roller portion 22a and in a truncated cone shape. And the taper surface formed in the inner peripheral surface of the fixed ring 21a and the movable ring 21b is in contact with the taper surface of this small diameter roller part 22b. With such a configuration, each planetary roller 22 can rotate while revolving around the sun roller 20. The carrier 23 is a ring-shaped member, and the output shaft 7 is inserted into a hole in the center portion and fixed so as not to rotate relative to each other. The carrier 23 and the output shaft 7 can be formed integrally.
[0040]
Next, the transmission means 4 will be described. The transmission means 4 includes a housing 31, an output shaft 7, a speed detection mechanism 8, and the like. The housing 31 mainly includes an outer wall portion 32 disposed around the output shaft 7 and a first partition wall portion 33 and a second partition wall portion 34 formed therein. As shown in FIGS. 2 and 3, the outer wall portion 32 has a generally rectangular tube shape. On the axial output side (driven device side) of the outer wall portion 32, a detection member insertion window portion 32a for housing the magnetic foil 25 in the housing 31 and two detection means insertion portions for attaching the sensor 26 are inserted. A window portion 32b is formed. The magnetic foil 25 and the sensor 26 are members constituting the speed detection mechanism 8 and will be described in detail later.
[0041]
The detection member insertion window portion 32 a has a rectangular shape that is long on one wall surface of the outer wall portion 32 in the circumferential direction. The detection means insertion window 32b has a rectangular shape that is long in the circumferential direction on two wall surfaces that face each other on a wall surface different from the wall surface on which the detection member insertion window portion 32a of the outer wall portion 32 is formed. is there. The opening width dimension of the detection member insertion window 32a is somewhat larger than the outer dimension of the magnetic foil 25 so that the magnetic foil 25 can be easily inserted. The opening width dimension of the detection member insertion window portion 32 b is substantially the same as the outer dimension of the sensor 26 for mounting the sensor 26. Each detection means insertion window 32b is shorter in the circumferential direction than the detection member insertion window 32a. The detected member insertion window 32a and the detection means insertion window 32b are both open in the radial direction.
[0042]
More specifically, the detected member insertion window portion 32a is a hole penetrating the outer wall portion 32 in the first radial direction of the output shaft 7, and the center axis (circumferential direction and axial direction of the hole) of the hole. (The axis extending in the first radial direction) is orthogonal to the output shaft 7. The detection means insertion window 32b is a hole penetrating the outer wall 32 in the second radial direction of the output shaft 7, and the center axis of the hole (the circumferential direction and the axial center of the hole are the second). (Axis extending in the radial direction) is orthogonal to the output shaft 7.
[0043]
A first partition wall 33 is integrally formed at the driven device side end of the outer wall 32. The first partition wall 33 is substantially rectangular and is formed with a circular center hole 33a through which the output shaft 7 passes. At each corner of the first partition wall 33, an attachment hole is formed for fixing the attachment hole to the driven device. A first bearing 27 that rotatably supports the output shaft 7 is provided on the inner peripheral surface of the center hole 33 a of the first partition wall 33. The first bearing 27 is a ball bearing having a sealing function for preventing the lubricant from flowing out from the inside of the bearing and preventing foreign matter from entering from the outside to the inside of the bearing. The first bearing 27 has an outer race fitted into the center hole 33a, and the axial input side is supported by a flange 33c formed in the center hole 33a. The inner race of the first bearing 27 is locked with a snap ring 42 attached to the output shaft 7 on the axial output side thereof, thereby preventing the inner race from moving to the axial output side. Has been.
[0044]
Further, in the first partition wall 33, a pair of sensor adjustment windows 33b are formed on both sides of the center hole 33a. Each sensor adjustment window 33b is close to two detection means insertion windows 32b formed on the outer wall 32, respectively. The sensor adjustment window 33 b is a hole that passes through the first partition wall 33 in the axial direction of the output shaft 7, and the center axis of the hole is parallel to the output shaft 7. The adjustment window 33b is used to insert a positioning jig therein and accurately position the sensor 26 with respect to the magnetic foil 25.
[0045]
The second partition wall portion 34 is formed integrally with the outer wall portion 32, but is separated from the first partition wall portion 33 toward the axial direction input side (reduction gear side). Therefore, a rectangular accommodation space 35 covered with the outer wall 32 is secured between the first partition wall 33 and the second partition wall 34 in the axial direction. The detected member insertion window 32a, the detection means insertion window 32b, and the adjustment window 33b are in communication with the accommodation space 35. In this sense, these windows are a part of the accommodation space 35. It may be considered that it constitutes.
[0046]
The second partition wall 34 has a substantially rectangular shape and a circular center hole 34a through which the output shaft 7 passes. A second bearing 28 that rotatably supports the output shaft 7 is provided on the inner peripheral surface of the center hole 34 a of the second partition wall 34. The second bearing 28 is also a ball bearing having the same sealing function as the first bearing 27. The second bearing 28 has an outer race supported by a center hole 34a and an axial output side supported by a flange 34c formed in the center hole 34a via a wave washer 36. Further, the inner race of the second bearing 28 is in contact with the carrier 23 on the axial direction input side, thereby restricting movement of the inner race to the axial direction input side.
[0047]
As described above, the housing space 35 and the space on the reduction gear 3 side are separated in the axial direction by the second partition wall 34 and the second bearing 28, and the second bearing 28 has a sealing function. . Therefore, when the lubricant such as grease is filled in the reduction gear 3, the lubricant can be prevented from entering the speed detection mechanism 8. Further, it is possible to suppress the dust (in the case of a dry type) and wear powder generated in the reduction gear 3 from entering the speed detection mechanism 8 side. Therefore, speed detection can be performed with high accuracy.
[0048]
As described above, the first bearing 27 and the second bearing 28 are mounted on the inner peripheral surfaces of the first partition wall 33 and the second partition wall 34, respectively, and rotatably support the output shaft 7. Here, since the first bearing 27 and the second bearing 28 sandwich the magnetic foil 25 and the like (described later) in the axial direction, they are separated from each other in the axial direction. Therefore, the radial rigidity of the output shaft 7 is higher than that of a structure in which the same two bearings are arranged close to each other in the axial direction.
[0049]
On the speed reduction device 3 side of the second partition wall portion 34, a plurality (six in this embodiment) of storage recesses 34b are formed that are arranged at equal intervals in the circumferential direction. The storage recess 34b extends long toward the axial output side. A coil spring 29 is disposed in the storage recess 34b. The coil spring 29 always urges the movable ring 21b toward the fixed ring 21a via the washer 29a. As a result, a predetermined pressure contact force is applied to each contact surface between the large-diameter roller portion 22a of each planetary roller 22 and the sun roller 20, and each contact surface between each small-diameter roller portion 22b, the fixed ring 21a, and the movable ring 21b. Can be given. Accordingly, torque is transmitted to each contact portion by a traction method, and each planetary roller 22 can revolve while rotating around the sun roller 20.
[0050]
As described above, since the coil spring 29 is disposed not on the motor 2 side but on the second partition wall 34 side and further disposed in the second partition wall 34, the axial dimension of the rotary drive device 1 is shortened. More specifically, the bottom surface of the storage recess 34b extends further to the axial output side than the end surface of the second bearing 28 on the speed reducer 3 side. This means that the second bearing 28 and the recess 34b are at least partially in the same axial position, and both overlap in the radial direction. That is, the axial dimension of the rotary drive device 1 can be shortened by the axial dimension in which the coil spring 29 and the second bearing 28 overlap in the radial direction.
[0051]
Since a coil spring is used as the urging member, a stable pressure contact force can always be obtained. A wave spring may be used as the urging member. In that case, the axial dimension is further shortened as compared with the coil spring. Further, the biasing member may be omitted, and the internal ring itself may be configured to apply a biasing force to the planetary roller 22. For example, a ring having a U-shaped cross section applies a biasing force to the planetary roller. For example, a configuration in which the urging force is applied to the outer diameter portion of the planetary roller and a ring member that applies a biasing force inward in the radial direction can be given.
[0052]
The housing 31 further has a cylindrical second outer wall portion 39 extending from the outer wall portion 32 toward the axial direction input side. The second outer wall portion 39 is formed integrally with the outer wall portion 32 and covers the periphery of the reduction gear 3. That is, the second outer wall portion 39 constitutes the housing of the reduction gear 3. The outer wall surface of the second wall portion 39 has the same rectangular tube shape as the outer wall portion 32, and the inner wall surface has a large-diameter cylindrical shape along the revolution orbit of the planetary roller 22 of the reduction gear 3 and the outer diameter of the carrier 23. It consists of a small-diameter cylindrical shape along. The distal end (motor 2 side) of the second outer wall portion 39 abuts on the support member 10d of the bracket 10 and is fixed to each other by the bolt 9 described above. As described above, since the housing of the transmission means 4 and the housing of the reduction gear 3 are integrally formed, the number of parts is reduced and the configuration is simplified.
[0053]
The output shaft 7 is an axis extending from the reduction gear 3 to the driven device side, and a carrier 23 is fixed to the end of the reduction gear 3 side. The output shaft 7 is disposed concentrically with the rotational drive shaft 14 of the motor 2. As described above, the output shaft 7 passes through the first partition wall 33 and the second partition wall 34 in the housing 31. More specifically, the output shaft 7 is rotatably supported by the first bearing 27 mounted in the center hole 33a in the first partition wall 33, and the second partition wall 34 is mounted in the center hole 34a. Two bearings 28 are rotatably supported.
[0054]
The speed detection mechanism 8 is a mechanism for detecting the output rotation speed of the reduction gear 3 that is disposed in the accommodation space 35 of the housing 31. The speed detection mechanism 8 is a magnetic rotary encoder, and is arranged with a magnetic foil 25 that is non-rotatably locked to the outer peripheral surface of the output shaft 7 and a predetermined gap in the radial direction from the outer peripheral surface of the magnetic foil 25. And a pair of magnetic sensors 26. The magnetic foil 25 is a generally disc-shaped plastic magnet and has a center hole 25a through which the output shaft 7 passes. On the outer periphery of the magnetic foil 25, for example, about 650 N poles and S poles are alternately magnetized at equal intervals in the circumferential direction.
[0055]
A locking structure between the magnetic foil 25 and the output shaft 7 will be described. As shown in FIG. 4, on the side surface of the motor 2 of the magnetic foil 25, a pair of grooves 25b extending linearly in the radial direction are formed at two locations facing the radial direction of the center hole 25a. Further, a hole 7a penetrating in the radial direction is formed in the vicinity of the middle in the axial direction of the output shaft 7, and a detent pin 30 is fitted therein. Both ends of the non-rotating pin 30 protrude outside the output shaft 7 and fit into a pair of grooves 25b. For this reason, the magnetic foil 25 rotates integrally with the output shaft 7 in the engaged state. Further, the length of the anti-rotation pin 30 is shorter than the length between the radially outer ends of the pair of grooves 25b, and is shorter than the diameter of the center hole 34a of the second partition wall portion 34.
[0056]
The anti-rotation pin 30 and the pair of grooves 25b can be easily engaged and disengaged in the axial direction, and the mounting property is improved. A wave washer 41 is disposed between the first bearing 27 and the magnetic foil 25, and the wave washer 41 urges the magnetic foil 25 toward the detent pin 30. For this reason, the magnetic foil 25 maintains the state engaged with the rotation prevention pin 30.
[0057]
As a method of fixing the magnetic foil 25 to the output shaft 7 so as not to rotate integrally, the magnetic foil can be screwed to the output shaft using a set bolt. In that case, it is necessary to secure a thick portion having a certain axial dimension in order to secure the screw hole. Therefore, there is a problem that it is difficult to form a screw hole when the axial dimension is limited. Further, a snap ring can be used in place of the wave washer as a member for engaging the rotation preventing pin 30 and the groove 25b with each other. However, in that case, the preload applied to the magnetic foil is not stable, and the width tolerance of the magnetic foil must be set precisely. Even if the member is thermally expanded, the wave washer is always given a predetermined preload to the magnetic foil 25, so that the mounting accuracy is hardly distorted. The structure of this embodiment is excellent in the above points.
[0058]
The pair of magnetic sensors 26 are each composed of a magnetoresistive effect element (MR element), and are disposed at positions facing each other (at intervals of 180 °). More specifically, each magnetic sensor 26 is disposed in each detection means insertion window 32b. The MR element of each magnetic sensor 26 is close to the magnetic foil 25, and the proximity portion corresponds to the sensor adjustment window 33b.
[0059]
The controller 5 is a control circuit including a crystal oscillator, a frequency divider, a phase difference detection unit, a drive pulse output unit, and the like. Based on detection outputs from the two magnetic sensors 26, the output rotation speed is set to a desired set value. This is a circuit for outputting motor drive pulses. The drive device 6 is a device for driving the motor 2 based on the drive pulse from the controller 5. Components constituting the controller 5 and the drive device 6 are mounted on the base substrate 10c.
[0060]
The controller 5 and the drive device 6 described above are feedback control means for realizing a function of controlling the driving state of the motor 2 based on the speed detection result of the speed detection mechanism 8.
[0061]
(2) Operation In the motor 2, when required power is supplied to the stator 11, the rotor 12 is rotationally driven by the electromagnetic action between the stator 11 and the rotor magnet 16 of the rotor 12. As a result, the rotation drive shaft 14 rotates, and this rotation is input to the reduction gear 3. This rotation is decelerated by a reduction ratio determined by the outer diameter and inner diameter of the sun roller 20, the planetary roller 22, and the internal ring 21, and is output via the carrier 23 and the output shaft 7.
[0062]
The rotational speed of the output shaft 7 is detected as a pulse signal by the magnetic foil 25 and the pair of magnetic sensors 26, and this pulse signal is input to the controller 5. The controller 5 compares the detection signals of the two magnetic sensors 26 to synthesize the rotation signal of the output shaft 7 in a state where the magnetic foil 25 is correctly attached. Then, the phase difference between this synthesized signal and the rotation reference pulse (pulse corresponding to the uniform rotation of the output shaft 7) is detected, and a control signal that eliminates this phase difference is input to the drive device 6. This control is described in detail in Japanese Patent Application Laid-Open No. 11-341854. Then, the rotational speed of the motor 2 is increased or decreased by a drive signal from the drive device 6.
[0063]
By such feedback control, the rotation speed of the motor 2 is controlled so that the output rotation speed of the reduction gear 3 becomes a desired set speed.
(3) Assembly Next, the assembly operation of the transmission means 4 will be described with reference to FIG. FIG. 3 is a schematic diagram for explaining the relationship between the members, and the shape and the like are simplified.
[0064]
A second bearing 28 and a wave washer 36 are assembled to the output shaft 7 in advance, and a detent pin 30 is further fitted therein. Next, the magnetic foil 25 is guided in the direction of arrow Y from the detected member insertion window 32 a and temporarily placed in the accommodation space 35. Then, the output shaft 7 is inserted into the housing 31 from the second partition wall portion 34 toward the first partition wall portion 33. The tip of the output shaft 7 passes through the center hole 34a of the second partition wall 34, then passes through the center hole 25a of the magnetic foil 25, and further passes through the center hole 33a of the first partition wall 33, It protrudes outside the first partition wall 33. At this time, the detent pin 30 passes through the center hole 34 a of the second partition wall 34 and enters the groove 25 b of the magnetic foil 25. Next, the wave washer 41 is fitted from the tip of the output shaft 7 and inserted into the center hole 33 a of the first partition wall 33. Further, the first bearing 27 is fitted from the tip of the output shaft 7 and pushed until it comes into contact with the flange 34c of the center hole 33a, and the snap ring 42 is attached to the outer peripheral surface of the output shaft 7. The wave washer 41 is compressed in the axial direction between the inner race of the first bearing 27 and the inner peripheral portion of the magnetic foil 25. Therefore, the movement of the magnetic foil 25 in the rotational direction is restricted by the anti-rotation pin 30, and the movement in the axial direction is restricted by being sandwiched between the anti-rotation pin 30 and the wave washer 41, and is fixed to the output shaft 7. Yes.
[0065]
Subsequently, the magnetic sensor 26 is attached to the detection means insertion window 32b. At that time, it is necessary to accurately set the distance between the MR element of the magnetic sensor 26 and the outer peripheral surface of the magnetic foil 25. Therefore, a magnetic sensor is inserted so that a positioning jig (a gap gauge having a thickness equal to the minute gap width) is inserted from the adjustment window 33b and the jig is sandwiched between the magnetic foil 25 and the MR element. 26 is moved in the second radial direction. When the magnetic sensor 26 is fixed while the magnetic sensor 26 is in contact with the jig and the jig is removed, a desired minute gap is secured between the magnetic foil 25 and the MR element. As a result, even if the speed detection mechanism 8 is housed inside the integrally formed housing 31, the magnetic sensor 26 can be attached with very high accuracy and easily. The distance between the magnetic foil 25 and the MR element is, for example, several tens of μm. Thereafter, the detection member insertion window 32a, the detection member insertion window 32b, and the adjustment window 33b are sealed with a sealing tape (not shown) to prevent dust and the like from entering the housing space 33. (4) Operational effect The feature of the present invention is “the housing is integrally formed”, and the following effects are produced.
[0066]
<1> Reduction in the number of parts Conventionally, a housing composed of a plurality of parts is formed by integral molding, and a member (seal only for preventing impurities in the speed detection mechanism by the second partition wall and the second bearing) As a result, the number of parts as a whole can be reduced.
[0067]
<2> Reduction of housing manufacturing cost Since it is an integral molding, it has become possible to manufacture a highly accurate and complicated shape with a short man-hour, thereby reducing the manufacturing cost.
[0068]
<3> Facilitating component mounting The housing becomes a relatively complicated shape by integral molding, which may impair the mounting capability of the speed detection mechanism, the bearing, etc., but by properly arranging the windows in the present invention, The speed detection mechanism and bearings can be easily installed without impairing the mounting properties.
[0069]
<4>
Reduction of assembly man-hours Since the number of parts is reduced compared to the prior art and additional shapes such as windows are provided in the housing to facilitate mounting of parts, the total assembly man-hours are reduced.
[0070]
<5> Improving assembly accuracy With conventional multi-part configurations, assembly errors are accumulated in addition to individual component errors, making it difficult to improve overall accuracy. However, assembly errors have been eliminated by molding the housing integrally. . As a result, it was easy to assemble with reference to the housing surface, and the assembly accuracy was improved.
[0071]
<6> Improved performance of parts themselves Assembly accuracy and strength have been improved by improving the surface accuracy and rigidity of the housing. As a result, high rotational accuracy and strength that can withstand long-term operation were realized. In addition, dust resistance to the speed detection mechanism has been improved, enabling stable operation over a long period of time.
[0072]
<7> Enhancement of radial load Since the speed detection mechanism is provided on the output side, the distance between the pair of bearings that support the output shaft can be increased. As a result, a higher radial loadability was realized compared to the previous example.
[0073]
<8>
The aim of shortening the axial direction in the present gun invention is considered to be small.
2. Second Embodiment In the above embodiment, two magnetic sensors are provided. However, as shown in FIG. 5, one magnetic sensor may be omitted and one magnetic sensor 26 may be used. Accordingly, one detection means insertion window 32b and one adjustment window 33b can be omitted, but the other basic structure is the same as that of the above embodiment.
[0074]
3. Third Embodiment In each of the above embodiments, the detection member insertion window 32a and the detection means insertion window 32b are provided separately. However, as shown in FIGS. 6 and 7, the magnetic sensor 26 is provided. May be attached to the detection member insertion window 32a, and the detection means insertion window 32b may be omitted. Therefore, the detection member insertion window 32 a has a function of inserting the magnetic foil 25 into the accommodation space 35 and a function of disposing the magnetic sensor 26. Further, the adjustment window portion 33 d is provided on the upper portion of the first partition wall portion 33 so as to correspond to the magnetic sensor 26. In this case, the detected member insertion window 32a is sufficiently larger than the magnetic sensor 26, and therefore, the magnetic sensor 26 may be attached by interposing a spacer or the like between the window 32a and the like.
[0075]
4). Fourth Embodiment In any of the above embodiments, the detection means window 33e is provided on the outer wall 32. However, as shown in FIG. 8, detection for attaching a magnetic sensor to the first partition wall 33 of the housing 31 is performed. A means insertion window 33e may be provided. The detection means insertion window 33e is opened so that the central axis of the hole is parallel to the output shaft 7. When the adjustment window is provided, it may be provided on the outer wall. Of course, a pair of magnetic sensors may be provided to improve detection accuracy.
[0076]
5. Fifth Embodiment An optical detection mechanism may be used instead of the magnetic detection mechanism of the above embodiment. As shown in FIG. 9, the speed detection mechanism 51 is an optical rotary encoder, and includes a pulse disk 52 and a photodetector 53 including a projector and a light receiver. On the outer peripheral portion of the pulse disc 52, light transmitting portions such as a plurality of slits are arranged at equal intervals in the circumferential direction. The photodetector 53 is U-shaped, and a portion where the light transmission part of the pulse disk 52 is formed enters the gap. The pulse disk 52 is fixed to the foil 55. Since the structure of the foil 55 and the relationship with other members are the same as those of the magnetic foil of the above embodiment except that the outer dimensions are small, the description thereof is omitted here. The photodetector 53 is fixed to the detected member insertion window 32a and is incorporated so as to enter the inside of the apparatus.
[0077]
6). Other Embodiments The outer wall portion of the housing is not limited to a generally rectangular tube shape, but may be a cylindrical shape.
[0078]
The shape of the window is not limited to a rectangle, and may be various shapes such as a circle. In the above embodiment, the member constituting the speed reducer is a friction wheel such as a roller, and the traction method is used between the sun roller and each planetary roller and between each planetary roller and the internal ring. Some may be used. Furthermore, a speed reducer called a parent-child type or a speed reducer disclosed in Japanese Patent Application No. 2000-307696 may be used.
[0079]
【The invention's effect】
In the rotary drive device according to the present invention, a member that is conventionally formed by integrally molding a housing that has been configured by a plurality of parts, and a member only for preventing impurities in the speed detection mechanism by the second partition wall and the second bearing. By eliminating the need for (seal members), the total number of parts and processing man-hours can be reduced. In addition, the rigidity and assembly accuracy of the housing are improved, and the speed detection mechanism is not contaminated, so it operates stably for a long period of time. can do. Further, by providing the housing with various window portions related to the arrangement of the speed detection mechanism, the speed detection mechanism can be easily and accurately attached even to an integrally molded housing.
[Brief description of the drawings]
FIG. 1 is a cross-sectional configuration diagram of a rotary drive device according to a first embodiment of the present invention.
FIG. 2 is a front view of the rotary drive device as seen in the direction of arrow II in FIG.
FIG. 3 is an exploded perspective view of a transmission means.
FIG. 4 is a diagram showing an engagement state between a magnetic foil and an output shaft.
FIG. 5 is a front view of a rotary drive device according to a second embodiment.
FIG. 6 is a cross-sectional configuration diagram of a rotary drive device according to a third embodiment.
7 is a view taken along arrow VII in FIG. 6;
FIG. 8 is a front view of a rotary drive device according to a fourth embodiment.
FIG. 9 is a cross-sectional configuration diagram of a rotary drive device according to a fifth embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rotation drive apparatus 2 Motor 3 Deceleration apparatus 4 Transmission means 5 Controller 6 Drive apparatus 7 Output shaft 8 Speed detection mechanism 25 Magnetic foil (detected member)
25b Groove (second engaging part)
26 Magnetic sensor (detection means)
27 First bearing 28 Second bearing 29 Coil spring (biasing member)
30 Non-rotating pin (first engaging part)
31 Housing 32 Outer Wall 32a Detected Member Insertion Window (First Window)
32b Detection means insertion window (second window)
33 First partition 33b Adjusting window 34 Second partition 35 Housing space 39 Second outer wall 41 Wave washer (elastic member)

Claims (14)

A rotational drive device that uses a motor as a rotational drive source, rotationally drives the driven device, detects an output rotational speed, and feedback controls the drive rotational speed of the motor,
A reduction gear driven by the motor;
An output shaft extending from the reduction gear toward the driven device, and transmission means for transmitting the output of the reduction gear to the driven device;
A speed detecting mechanism that is disposed on the driven device side of the speed reducer and detects the rotational speed of the output shaft;
An outer wall covering the periphery of the output shaft and the speed detection mechanism, a first partition wall formed integrally with the outer wall on the driven device side and having a central hole through which the output shaft passes, and the outer wall A housing having a second partition wall formed integrally with the speed reducer side and having a center hole through which the output shaft passes,
A first bearing disposed between an inner peripheral surface of a center hole of the first partition wall and the output shaft;
A second bearing disposed between an inner peripheral surface of a center hole of the second partition wall and the output shaft ;
With
The speed detection mechanism includes a detection unit and a detected member detected by the detection unit,
The detected member has a substantially disc shape having a center hole that is movably fitted in the axial direction with respect to the output shaft,
The second partition wall, together with the first partition wall and the outer wall, forms an accommodation space where the speed detection mechanism is installed , and separates the speed reduction device and the speed detection mechanism in the axial direction ,
The housing is formed with a first window portion that penetrates the outer wall portion in the radial direction of the output shaft, a central axis of which extends in the penetration direction and is orthogonal to the output shaft,
The width dimension of the first window is formed larger than the outer dimension of the detected member,
The detected member is disposed in the accommodating space through the first window, and the output shaft is inserted into the housing in that state, so that the output shaft is connected to the central hole of the second partition wall, A rotation drive device characterized by passing through the center hole of the member to be detected and the center hole of the first partition wall . The rotation drive device according to claim 1, further comprising a second window portion in which the detection unit is disposed . The second window portion penetrates the outer wall portion in a radial direction of the output shaft, and a central axis of the second window portion extends in the penetration direction and is orthogonal to the output shaft. The rotation drive device according to 2. The rotary drive device according to claim 3, wherein the housing is provided with an adjustment window for adjusting an attachment position when the detection means is disposed . The adjustment window portion passes through the first partition wall portion in the axial direction of the output shaft, and a central axis of the adjustment window portion extends in the penetration direction and is parallel to the output shaft. Item 5. The rotational drive device according to Item 4. The speed detection mechanism is a magnetic sensor, the detection means is at least one magnetic detection means for detecting a change in magnetic flux, and the detection member is a magnetic detection member having a magnetized portion. The rotational drive apparatus in any one of Claims 2-5 . The speed detection mechanism is an optical sensor, the detection means is at least one optical detection means for detecting an optical change, and the detected member is an optically detected member. The rotational drive apparatus in any one of. The output shaft has a first engaging portion, and the detected member has a second engaging portion that engages with the first engaging portion in a relatively non-rotatable manner and is detachable in the axial direction. And an elastic member that urges the member to be detected in the axial direction so that the first engagement portion and the second engagement portion engage with each other. The rotational drive device described. The said 2nd engaging part is formed in the surface at the side of the said deceleration device of the said to-be-detected member, The said elastic member is arrange | positioned between the said 1st bearing and the to-be-detected member . Rotation drive device. The reduction gear includes a solar wheel to which rotation of the motor is input, an internal ring disposed concentrically with the solar wheel, abutting the solar wheel, and receiving a biasing force from the internal ring. The rotation drive device according to claim 1, further comprising: a plurality of planetary vehicles in contact with each other; and a carrier that supports the plurality of planetary vehicles and is connected to the output shaft . The rotary drive device according to claim 10 , wherein an output shaft of the motor constitutes the solar wheel of the reduction gear. A recess for accommodating the urging member is formed on a surface of the second partition wall on the speed reduction device side, and a bottom surface of the recess is further on the driven device side than an end surface of the second bearing on the speed reduction device side. The rotary drive device according to claim 10 or 11 , wherein the rotary drive device is located. The rotary drive device according to any one of claims 1 to 12, wherein the housing further includes a second outer wall portion that is integrally formed with the outer wall portion and covers the periphery of the speed reduction device. The rotary drive device according to claim 1, further comprising feedback control means for performing feedback control of the drive speed of the motor based on detection from the speed detection mechanism .

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